diff --git a/Cargo.lock b/Cargo.lock
index 19b57a59..00cfd3d6 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3856,6 +3856,7 @@ dependencies = [
  "tower-http",
  "tracing",
  "tracing-subscriber",
+ "unicode-normalization",
  "urlencoding",
  "utoipa",
  "uuid",
diff --git a/Cargo.toml b/Cargo.toml
index 6843402e..42fa985e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -44,6 +44,7 @@ mp3-duration = "0.1"
 kamadak-exif = "0.6.1"
 md-5 = "0.11.0"
 sha2 = "0.11.0"
+unicode-normalization = "0.1.24"
 blake3 = { version = "1.8.4", features = ["rayon", "mmap"] }
 hex = "0.4.3"
 http-body-util = "0.1.3"
@@ -87,6 +88,10 @@ unexpected_cfgs = { level = "warn", check-cfg = ['cfg(integration_tests)'] }
 name = "generate-openapi"
 path = "src/bin/generate-openapi.rs"
 
+[[bin]]
+name = "migrate-nfc-filenames"
+path = "src/bin/migrate-nfc-filenames.rs"
+
 [build-dependencies]
 oxc_allocator = "0.125.0"
 oxc_parser = "0.125.0"
diff --git a/Dockerfile b/Dockerfile
index bce8aa0b..59dc48e2 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -14,6 +14,7 @@ COPY static static
 RUN mkdir -p src/bin && \
     echo 'fn main() { println!("Dummy build for caching dependencies"); }' > src/main.rs && \
     echo 'fn main() {}' > src/bin/generate-openapi.rs && \
+    echo 'fn main() {}' > src/bin/migrate-nfc-filenames.rs && \
     cargo build --release && \
     rm -rf src static-dist target/release/deps/oxicloud* target/release/build/oxicloud-*
 
@@ -56,6 +57,12 @@ RUN apk --no-cache upgrade && \
 
 # Copy the compiled binary and entrypoint (--chmod avoids extra RUN chmod layers)
 COPY --from=builder --chmod=755 /app/target/release/oxicloud /usr/local/bin/
+# Ship the NFC filename migration binary alongside the server so
+# operators can run it inside the container without a separate Rust
+# toolchain — `docker exec <container> migrate-nfc-filenames --dry-run`
+# to preview, drop `--dry-run` to execute. One-shot tool, safe to
+# ship; it only mutates `storage.files` rows whose name ≠ NFC(name).
+COPY --from=builder --chmod=755 /app/target/release/migrate-nfc-filenames /usr/local/bin/
 COPY entrypoint.sh /usr/local/bin/entrypoint.sh
 RUN sed -i 's/\r//' /usr/local/bin/entrypoint.sh && \
     chmod 755 /usr/local/bin/entrypoint.sh
diff --git a/migrations/20260625000000_folder_tree_modified_at.sql b/migrations/20260625000000_folder_tree_modified_at.sql
new file mode 100644
index 00000000..881d320d
--- /dev/null
+++ b/migrations/20260625000000_folder_tree_modified_at.sql
@@ -0,0 +1,104 @@
+-- Folder rollup ETag: introduce `storage.folders.tree_modified_at`,
+-- which is bumped whenever any descendant (file or folder) changes.
+--
+-- Motivation: WebDAV / NextCloud sync clients use a collection's ETag
+-- to decide "did anything change inside this folder since I last
+-- looked?". Until now `Folder::etag()` returned the folder UUID
+-- (constant for the row's life), which made the answer always "no" —
+-- forcing clients to do periodic deep PROPFIND walks to discover new
+-- files. With this column, `Folder::etag()` becomes
+-- `{id_short}-{tree_modified_at}` and clients can do O(changed)
+-- recursion instead of O(tree).
+--
+-- The two triggers cascade an update timestamp up the ltree ancestor
+-- chain on every file write and every folder mutation. Performance
+-- ceiling: O(depth) row updates per mutation; deep concurrent writes
+-- to the same root subtree can contend on the root row.
+
+ALTER TABLE storage.folders
+    ADD COLUMN tree_modified_at TIMESTAMPTZ NOT NULL DEFAULT NOW();
+
+-- Backfill existing rows: collapse the rollup timestamp to the
+-- per-folder updated_at. Clients re-walking after deploy will see
+-- one batch of "looks new to me" responses, which they handle as a
+-- content-match-no-download — the expected one-time resync wave.
+UPDATE storage.folders SET tree_modified_at = updated_at;
+
+
+-- File-side trigger: any INSERT/UPDATE/DELETE on storage.files
+-- bumps the file's parent folder + all its ancestors in the ltree.
+-- Root-level files (folder_id IS NULL) have no ancestors and do not
+-- trigger any folder bump — the root listing isn't an etag-emitting
+-- collection in OxiCloud's model (no virtual root folder row).
+CREATE OR REPLACE FUNCTION storage.bump_folder_tree_from_file()
+RETURNS TRIGGER LANGUAGE plpgsql AS $$
+DECLARE
+    target_folder_id UUID;
+    target_lpath ltree;
+BEGIN
+    target_folder_id := COALESCE(NEW.folder_id, OLD.folder_id);
+    IF target_folder_id IS NULL THEN
+        RETURN COALESCE(NEW, OLD);
+    END IF;
+
+    SELECT lpath INTO target_lpath
+      FROM storage.folders
+     WHERE id = target_folder_id;
+
+    IF target_lpath IS NULL THEN
+        RETURN COALESCE(NEW, OLD);
+    END IF;
+
+    -- `lpath @> target_lpath` matches the target folder AND every
+    -- ancestor up to the root. The GiST index on lpath keeps this
+    -- to an index range scan even on deep trees.
+    UPDATE storage.folders
+       SET tree_modified_at = NOW()
+     WHERE lpath @> target_lpath;
+
+    RETURN COALESCE(NEW, OLD);
+END;
+$$;
+
+CREATE TRIGGER files_bump_folder_tree_etag
+    AFTER INSERT OR UPDATE OR DELETE ON storage.files
+    FOR EACH ROW EXECUTE FUNCTION storage.bump_folder_tree_from_file();
+
+
+-- Folder-side trigger: covers creates, deletes, renames, and moves.
+-- A folder move changes its lpath — the OLD chain and NEW chain
+-- both need bumping (old parents lost a child, new parents gained
+-- one). Self-exclusion (id <> the changed row) avoids the row
+-- bumping itself, which is meaningless and would amplify
+-- contention on hot paths.
+--
+-- The `pg_trigger_depth() > 1` guard breaks recursion: when this
+-- trigger UPDATEs ancestor rows below, those UPDATEs would fire
+-- the same trigger again. Without the guard, a single child
+-- creation would cascade an unbounded number of upward writes.
+CREATE OR REPLACE FUNCTION storage.bump_folder_tree_from_folder()
+RETURNS TRIGGER LANGUAGE plpgsql AS $$
+BEGIN
+    IF pg_trigger_depth() > 1 THEN
+        RETURN COALESCE(NEW, OLD);
+    END IF;
+
+    IF TG_OP IN ('DELETE', 'UPDATE') AND OLD.lpath IS NOT NULL THEN
+        UPDATE storage.folders
+           SET tree_modified_at = NOW()
+         WHERE lpath @> OLD.lpath AND id <> OLD.id;
+    END IF;
+
+    IF TG_OP IN ('INSERT', 'UPDATE') AND NEW.lpath IS NOT NULL THEN
+        UPDATE storage.folders
+           SET tree_modified_at = NOW()
+         WHERE lpath @> NEW.lpath AND id <> NEW.id;
+    END IF;
+
+    RETURN COALESCE(NEW, OLD);
+END;
+$$;
+
+CREATE TRIGGER folders_bump_folder_tree_etag
+    AFTER INSERT OR UPDATE OR DELETE ON storage.folders
+    FOR EACH ROW EXECUTE FUNCTION storage.bump_folder_tree_from_folder();
diff --git a/src/application/adapters/webdav_adapter.rs b/src/application/adapters/webdav_adapter.rs
index da4f1ccb..24dbde25 100644
--- a/src/application/adapters/webdav_adapter.rs
+++ b/src/application/adapters/webdav_adapter.rs
@@ -444,9 +444,11 @@ impl WebDavAdapter {
         xml_writer.write_event(Event::Text(BytesText::new(&modified_at.to_rfc2822())))?;
         xml_writer.write_event(Event::End(BytesEnd::new("D:getlastmodified")))?;
 
-        // Other standard properties
+        // ETag — routes through `FolderDto::etag` (= `Folder::etag()`)
+        // so every WebDAV emitter and HEAD response agree on a single
+        // value for the same folder.
         xml_writer.write_event(Event::Start(BytesStart::new("D:getetag")))?;
-        xml_writer.write_event(Event::Text(BytesText::new(&format!("\"{}\"", folder.id))))?;
+        xml_writer.write_event(Event::Text(BytesText::new(&format!("\"{}\"", folder.etag))))?;
         xml_writer.write_event(Event::End(BytesEnd::new("D:getetag")))?;
 
         // Content length (0 for directories)
@@ -505,9 +507,11 @@ impl WebDavAdapter {
         xml_writer.write_event(Event::Text(BytesText::new(&modified_at.to_rfc2822())))?;
         xml_writer.write_event(Event::End(BytesEnd::new("D:getlastmodified")))?;
 
-        // ETag
+        // ETag — routes through `FileDto::etag` (= `File::etag()`) so
+        // PROPFIND, GET, HEAD, PUT-response, and MOVE all emit
+        // byte-identical values for the same file.
         xml_writer.write_event(Event::Start(BytesStart::new("D:getetag")))?;
-        xml_writer.write_event(Event::Text(BytesText::new(&format!("\"{}\"", file.id))))?;
+        xml_writer.write_event(Event::Text(BytesText::new(&format!("\"{}\"", file.etag))))?;
         xml_writer.write_event(Event::End(BytesEnd::new("D:getetag")))?;
 
         Ok(())
@@ -589,7 +593,7 @@ impl WebDavAdapter {
                         xml_writer.write_event(Event::Start(BytesStart::new("D:getetag")))?;
                         xml_writer.write_event(Event::Text(BytesText::new(&format!(
                             "\"{}\"",
-                            folder.id
+                            folder.etag
                         ))))?;
                         xml_writer.write_event(Event::End(BytesEnd::new("D:getetag")))?;
                     }
@@ -685,7 +689,7 @@ impl WebDavAdapter {
                         xml_writer.write_event(Event::Start(BytesStart::new("D:getetag")))?;
                         xml_writer.write_event(Event::Text(BytesText::new(&format!(
                             "\"{}\"",
-                            file.id
+                            file.etag
                         ))))?;
                         xml_writer.write_event(Event::End(BytesEnd::new("D:getetag")))?;
                     }
diff --git a/src/application/dtos/favorites_dto.rs b/src/application/dtos/favorites_dto.rs
index 19d09cef..80852772 100644
--- a/src/application/dtos/favorites_dto.rs
+++ b/src/application/dtos/favorites_dto.rs
@@ -125,6 +125,10 @@ pub struct FavoriteResourceRow {
     pub resource_created_at: DateTime<Utc>,
     pub modified_at: DateTime<Utc>,
     pub owner_id: Uuid,
+    /// Raw BLAKE3 content hash. `Some(_)` for file rows, `None` for
+    /// folder rows. Routes into `FileDto::content_hash` and feeds
+    /// `File::compute_etag` to populate `FileDto::etag`.
+    pub blob_hash: Option<String>,
     /// `true` when `owner_id == requesting user_id`.
     pub is_owner: bool,
     pub favorited_at: DateTime<Utc>,
diff --git a/src/application/dtos/file_dto.rs b/src/application/dtos/file_dto.rs
index bc6af74c..b55031f7 100644
--- a/src/application/dtos/file_dto.rs
+++ b/src/application/dtos/file_dto.rs
@@ -62,14 +62,31 @@ pub struct FileDto {
     #[serde(skip_serializing_if = "Option::is_none")]
     pub sort_date: Option<u64>,
 
-    /// Content-addressable ETag (= blob_hash). Changes on every content write.
-    /// Used for WebDAV/Nextcloud ETag headers. Omitted from REST API JSON.
-    #[serde(skip)]
+    /// Raw BLAKE3 content hash. Populated from `File::content_hash()`.
+    /// Exposed in REST JSON so API consumers can use it for
+    /// content-addressable URLs, dedup verification, and integrity
+    /// audits. Distinct from `etag` (which is an HTTP-only cache
+    /// token whose formula may grow to include `modified_at` etc.).
+    pub content_hash: String,
+
+    /// Opaque HTTP ETag. Populated from `File::etag()`. Used by
+    /// WebDAV/NextCloud handlers when emitting `ETag` headers and
+    /// also exposed in REST JSON so frontends can pass it back
+    /// through `If-Match` / `If-None-Match` on download / mutation
+    /// endpoints without a separate HEAD round-trip.
     pub etag: String,
 }
 
 impl From<File> for FileDto {
     fn from(file: File) -> Self {
+        // Compute the HTTP ETag BEFORE consuming the entity —
+        // `File::etag()` derives from `blob_hash` + `modified_at`,
+        // so it must run against the live entity, not against
+        // already-extracted parts. `content_hash` is just the raw
+        // blob hash; `etag` is the cache token derived from it.
+        let etag = file.etag();
+        let content_hash = file.content_hash().to_string();
+
         // Consume the entity by moving all fields — zero heap allocations
         // for id, name, path, folder_id, owner_id (previously 5× .to_string()).
         let parts = file.into_parts();
@@ -95,7 +112,8 @@ impl From<File> for FileDto {
             size_formatted,
             owner_id: parts.owner_id.map(|u| u.to_string()),
             sort_date: None,
-            etag: parts.etag,
+            content_hash,
+            etag,
         }
     }
 }
@@ -150,6 +168,7 @@ impl FileDto {
             category: Arc::from("Document"),
             size_formatted: "0 Bytes".to_string(),
             owner_id: None,
+            content_hash: String::new(),
             etag: String::new(),
             sort_date: None,
         }
diff --git a/src/application/dtos/folder_dto.rs b/src/application/dtos/folder_dto.rs
index e411fab6..1cd5ca3a 100644
--- a/src/application/dtos/folder_dto.rs
+++ b/src/application/dtos/folder_dto.rs
@@ -73,11 +73,19 @@ pub struct FolderDto {
     /// Human-readable category (always "Folder")
     #[schema(value_type = String)]
     pub category: Arc<str>,
+
+    /// Opaque ETag for HTTP responses. Populated from `Folder::etag()`
+    /// at conversion time so every WebDAV / NextCloud handler emits
+    /// the same value, and exposed in REST JSON so the frontend can
+    /// pass it back through `If-Match` on rename / move endpoints
+    /// without a separate HEAD round-trip.
+    pub etag: String,
 }
 
 impl From<Folder> for FolderDto {
     fn from(folder: Folder) -> Self {
         let is_root = folder.parent_id().is_none();
+        let etag = folder.etag().to_string();
 
         Self {
             id: folder.id().to_string(),
@@ -91,6 +99,7 @@ impl From<Folder> for FolderDto {
             icon_class: Arc::from("fas fa-folder"),
             icon_special_class: Arc::from("folder-icon"),
             category: Arc::from("Folder"),
+            etag,
         }
     }
 }
@@ -141,6 +150,7 @@ impl FolderDto {
             icon_class: Arc::from("fas fa-folder"),
             icon_special_class: Arc::from("folder-icon"),
             category: Arc::from("Folder"),
+            etag: String::new(),
         }
     }
 }
@@ -171,6 +181,11 @@ pub struct FolderResourceRow {
     pub created_at: DateTime<Utc>,
     pub modified_at: DateTime<Utc>,
     pub owner_id: Uuid,
+    /// Raw BLAKE3 content hash. `Some(_)` for file rows, `None` for
+    /// folder rows. Populates `FileDto::content_hash` + `FileDto::etag`
+    /// on the REST `/api/folders/{id}/resources` listing so API
+    /// consumers can issue conditional requests against listed files.
+    pub blob_hash: Option<String>,
     // Pre-computed sort fields — returned by the SQL for cursor construction.
     /// `LOWER(name)` used by `name`/`type` sorts.
     pub sort_str: String,
diff --git a/src/application/dtos/recent_dto.rs b/src/application/dtos/recent_dto.rs
index cf3ca378..3eee591b 100644
--- a/src/application/dtos/recent_dto.rs
+++ b/src/application/dtos/recent_dto.rs
@@ -105,6 +105,10 @@ pub struct RecentResourceRow {
     pub resource_created_at: DateTime<Utc>,
     pub modified_at: DateTime<Utc>,
     pub owner_id: Uuid,
+    /// Raw BLAKE3 content hash. `Some(_)` for file rows, `None` for
+    /// folder rows. Feeds `File::compute_etag` so this listing's
+    /// `etag` matches GET/HEAD/PROPFIND for the same file.
+    pub blob_hash: Option<String>,
     /// `true` when `owner_id == requesting user_id`.
     pub is_owner: bool,
     pub accessed_at: DateTime<Utc>,
diff --git a/src/application/dtos/search_dto.rs b/src/application/dtos/search_dto.rs
index 24f4af9b..5713f712 100644
--- a/src/application/dtos/search_dto.rs
+++ b/src/application/dtos/search_dto.rs
@@ -127,6 +127,13 @@ pub struct SearchFileResultDto {
     pub icon_special_class: String,
     /// Content category: "document", "image", "video", "audio", "archive", "code", "other"
     pub category: String,
+    /// Raw BLAKE3 content hash. Feeds `FileDto::content_hash` and
+    /// `File::compute_etag` when search results are converted to
+    /// `FileDto` (NC REPORT/SEARCH response). Defaults to `String::new()`
+    /// for backward-compatible deserialisation of cached results
+    /// that pre-date the column.
+    #[serde(default)]
+    pub blob_hash: String,
 }
 
 /// A folder search result enriched with server-computed metadata
diff --git a/src/application/dtos/trash_dto.rs b/src/application/dtos/trash_dto.rs
index 5715c9ac..2cbe2e60 100644
--- a/src/application/dtos/trash_dto.rs
+++ b/src/application/dtos/trash_dto.rs
@@ -61,6 +61,12 @@ pub struct TrashResourceRow {
     pub resource_created_at: DateTime<Utc>,
     pub modified_at: DateTime<Utc>,
     pub owner_id: Uuid,
+    /// Raw BLAKE3 content hash. `Some(_)` for file rows, `None` for
+    /// folder rows. Feeds `File::compute_etag` so the trash listing's
+    /// `etag` matches what GET/HEAD/PROPFIND would return for the
+    /// same file (restorable trash items are conditional-request
+    /// targets too).
+    pub blob_hash: Option<String>,
     pub trashed_at: DateTime<Utc>,
     pub deletion_date: DateTime<Utc>,
     /// Original location path (for folders: `path`; for files: `parent.path || '/' || name`).
diff --git a/src/application/services/search_service.rs b/src/application/services/search_service.rs
index 1adaff83..5ce252ab 100644
--- a/src/application/services/search_service.rs
+++ b/src/application/services/search_service.rs
@@ -172,6 +172,10 @@ impl SearchService {
             icon_class: get_icon_class(&file.name, &file.mime_type),
             icon_special_class: get_icon_special_class(&file.name, &file.mime_type),
             category: get_category(&file.name, &file.mime_type),
+            // Carry the content hash through so REPORT/SEARCH
+            // responses on the NC surface can emit the same ETag
+            // (`File::compute_etag`) as PROPFIND/GET would.
+            blob_hash: file.content_hash.clone(),
         }
     }
 
diff --git a/src/application/services/trash_service.rs b/src/application/services/trash_service.rs
index 073aae40..935f294e 100644
--- a/src/application/services/trash_service.rs
+++ b/src/application/services/trash_service.rs
@@ -17,6 +17,7 @@ use crate::application::ports::file_lifecycle::FileLifecycleHook;
 use crate::application::ports::storage_ports::{FileReadPort, FileWritePort};
 use crate::application::ports::trash_ports::TrashUseCase;
 use crate::common::errors::{DomainError, ErrorKind, Result};
+use crate::domain::entities::file::File;
 use crate::domain::entities::trashed_item::{TrashedItem, TrashedItemType};
 use crate::domain::repositories::folder_repository::FolderRepository;
 use crate::domain::repositories::trash_repository::TrashRepository;
@@ -809,8 +810,10 @@ fn build_trash_cursor(row: &TrashResourceRow, order_by: &str, reverse: bool) ->
 fn row_to_item_dto(row: TrashResourceRow) -> TrashResourceItemDto {
     let path = row.path.clone().unwrap_or_default();
     if row.resource_type == "folder" {
+        let resource_id = row.resource_id.to_string();
         let dto = FolderDto {
-            id: row.resource_id.to_string(),
+            etag: resource_id.clone(),
+            id: resource_id,
             name: row.name.clone(),
             path,
             parent_id: row.parent_id.map(|u| u.to_string()),
@@ -834,6 +837,16 @@ fn row_to_item_dto(row: TrashResourceRow) -> TrashResourceItemDto {
             .as_deref()
             .unwrap_or("application/octet-stream");
         let size_bytes = row.size.max(0) as u64;
+        // Route ETag through `File::compute_etag` so trash items
+        // match GET/HEAD/PROPFIND ETags — a client restoring a
+        // file may conditional-request it immediately after.
+        let modified_at_u = row.modified_at.timestamp() as u64;
+        let content_hash = row.blob_hash.clone().unwrap_or_default();
+        let etag = if content_hash.is_empty() {
+            String::new()
+        } else {
+            File::compute_etag(&content_hash, modified_at_u)
+        };
         let dto = FileDto {
             id: row.resource_id.to_string(),
             name: row.name.clone(),
@@ -842,14 +855,15 @@ fn row_to_item_dto(row: TrashResourceRow) -> TrashResourceItemDto {
             mime_type: std::sync::Arc::from(mime),
             folder_id: row.parent_id.map(|u| u.to_string()),
             created_at: row.resource_created_at.timestamp() as u64,
-            modified_at: row.modified_at.timestamp() as u64,
+            modified_at: modified_at_u,
             icon_class: std::sync::Arc::from(icon_class_for(&row.name, mime)),
             icon_special_class: std::sync::Arc::from(icon_special_class_for(&row.name, mime)),
             category: std::sync::Arc::from(category_for(&row.name, mime)),
             size_formatted: format_file_size(size_bytes),
             owner_id: Some(row.owner_id.to_string()),
             sort_date: None,
-            etag: String::new(),
+            content_hash,
+            etag,
         };
         TrashResourceItemDto {
             resource_type: ResourceTypeDto::File,
diff --git a/src/bin/migrate-nfc-filenames.rs b/src/bin/migrate-nfc-filenames.rs
new file mode 100644
index 00000000..270eddb7
--- /dev/null
+++ b/src/bin/migrate-nfc-filenames.rs
@@ -0,0 +1,326 @@
+//! `migrate-nfc-filenames` — one-shot CLI to NFC-normalize
+//! `storage.files.name` across an OxiCloud instance.
+//!
+//! Why: PostgreSQL compares bytes literally and the `UNIQUE`
+//! index on `(folder_id, name, user_id) WHERE NOT is_trashed`
+//! does not catch Unicode normalization differences. macOS APFS
+//! stores filenames in NFD; browsers post NFC. A file uploaded
+//! from the web ("café.txt", NFC) and the same name re-uploaded
+//! from a NextCloud desktop client on macOS (round-tripped to
+//! NFD: `e` + combining acute) lands as two distinct rows, both
+//! visible in the listing, both pointing at the same blob.
+//!
+//! What this does:
+//!
+//! 1. Scans every non-trashed file row.
+//! 2. For each row whose name ≠ NFC(name):
+//!    - If no other row in the same `(folder_id, user_id)` already
+//!      holds the NFC form → UPDATE the row's name to NFC.
+//!    - If a collision exists with **same blob_hash**: trash the
+//!      newer of the two (`is_trashed = true`, `trashed_at = NOW()`).
+//!      User can restore from the trash UI if needed.
+//!    - If a collision exists with **different blob_hash**: rename
+//!      the newer row to `{nfc_name}.duplicate`, incrementing the
+//!      suffix (`.duplicate-1`, `.duplicate-2`, …) until a free name
+//!      is found. Preserves both files; user can inspect and resolve.
+//!    - In both collision cases, the surviving (older) row's name
+//!      is also normalized to NFC.
+//!
+//! Run:
+//!   `cargo run --bin migrate-nfc-filenames -- --dry-run`
+//!   `cargo run --bin migrate-nfc-filenames`
+//!
+//! Folder rows are NOT touched in this pass — trashing a folder
+//! affects descendants; that pass is deferred to a follow-up.
+
+use chrono::{DateTime, Utc};
+use sqlx::{PgPool, Row};
+use std::env;
+use uuid::Uuid;
+
+use oxicloud::domain::services::path_service::normalize_storage_name;
+
+#[derive(Debug, Clone)]
+struct FileRow {
+    id: Uuid,
+    folder_id: Option<Uuid>,
+    user_id: Uuid,
+    name: String,
+    blob_hash: String,
+    created_at: DateTime<Utc>,
+}
+
+#[derive(Default)]
+struct Stats {
+    scanned: u64,
+    already_nfc: u64,
+    normalized_in_place: u64,
+    deduped_same_content: u64,
+    renamed_duplicate: u64,
+}
+
+#[tokio::main]
+async fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let args: Vec<String> = env::args().collect();
+    let dry_run = args.iter().any(|a| a == "--dry-run");
+
+    let database_url =
+        env::var("DATABASE_URL").expect("DATABASE_URL must be set in the environment");
+
+    let pool = PgPool::connect(&database_url).await?;
+
+    println!(
+        "=== NFC filename migration ({}) ===",
+        if dry_run {
+            "DRY RUN — no writes"
+        } else {
+            "EXECUTING"
+        }
+    );
+    println!();
+
+    let rows = load_non_trashed_files(&pool).await?;
+    println!("Loaded {} non-trashed file rows", rows.len());
+    println!();
+
+    let mut stats = Stats {
+        scanned: rows.len() as u64,
+        ..Default::default()
+    };
+
+    for row in &rows {
+        let nfc_name = normalize_storage_name(&row.name);
+        if nfc_name == row.name {
+            stats.already_nfc += 1;
+            continue;
+        }
+
+        // Row is in non-NFC form. Look for a collision in the same
+        // (folder_id, user_id) scope, including rows that may also
+        // be non-NFC but happen to normalize to the same NFC value.
+        let collision = find_collision(&pool, row, &nfc_name).await?;
+
+        match collision {
+            None => {
+                println!(
+                    "NORMALIZE  {}  user={}  '{}' → '{}'",
+                    row.id, row.user_id, row.name, nfc_name
+                );
+                if !dry_run {
+                    sqlx::query("UPDATE storage.files SET name = $1 WHERE id = $2")
+                        .bind(&nfc_name)
+                        .bind(row.id)
+                        .execute(&pool)
+                        .await?;
+                }
+                stats.normalized_in_place += 1;
+            }
+            Some(other) => {
+                // Pick winner/loser by `created_at` — older wins.
+                let (older, newer) = if row.created_at <= other.created_at {
+                    (row, &other)
+                } else {
+                    (&other, row)
+                };
+
+                if older.blob_hash == newer.blob_hash {
+                    // Same content → trash the newer; promote older's
+                    // name to NFC if it isn't already.
+                    println!(
+                        "DEDUP      newer={} (trash, same blob)  older={}  user={}  hash={}",
+                        newer.id,
+                        older.id,
+                        older.user_id,
+                        &older.blob_hash[..16.min(older.blob_hash.len())]
+                    );
+                    if !dry_run {
+                        sqlx::query(
+                            "UPDATE storage.files
+                                SET is_trashed = TRUE,
+                                    trashed_at = NOW()
+                              WHERE id = $1",
+                        )
+                        .bind(newer.id)
+                        .execute(&pool)
+                        .await?;
+                        normalize_survivor_name(&pool, older, &nfc_name).await?;
+                    }
+                    stats.deduped_same_content += 1;
+                } else {
+                    // Different content → rename newer to a free
+                    // `{nfc_name}.duplicate[-N]`; promote older to NFC.
+                    let disambiguated = find_free_duplicate_name(&pool, newer, &nfc_name).await?;
+                    println!(
+                        "RENAME     newer={} (different blob)  older={}  '{}' → '{}'",
+                        newer.id, older.id, newer.name, disambiguated
+                    );
+                    if !dry_run {
+                        sqlx::query("UPDATE storage.files SET name = $1 WHERE id = $2")
+                            .bind(&disambiguated)
+                            .bind(newer.id)
+                            .execute(&pool)
+                            .await?;
+                        normalize_survivor_name(&pool, older, &nfc_name).await?;
+                    }
+                    stats.renamed_duplicate += 1;
+                }
+            }
+        }
+    }
+
+    println!();
+    println!("=== Summary ===");
+    println!("  scanned                            : {}", stats.scanned);
+    println!(
+        "  already in NFC                     : {}",
+        stats.already_nfc
+    );
+    println!(
+        "  normalized in place (no collision) : {}",
+        stats.normalized_in_place
+    );
+    println!(
+        "  dedup-trashed (same content)       : {}",
+        stats.deduped_same_content
+    );
+    println!(
+        "  renamed to .duplicate              : {}",
+        stats.renamed_duplicate
+    );
+    if dry_run {
+        println!();
+        println!("DRY RUN — no rows were written. Re-run without --dry-run to apply.");
+    }
+
+    Ok(())
+}
+
+async fn load_non_trashed_files(pool: &PgPool) -> Result<Vec<FileRow>, Box<dyn std::error::Error>> {
+    let raw = sqlx::query(
+        "SELECT id, folder_id, user_id, name, blob_hash, created_at
+           FROM storage.files
+          WHERE NOT is_trashed
+          ORDER BY created_at",
+    )
+    .fetch_all(pool)
+    .await?;
+
+    let mut out = Vec::with_capacity(raw.len());
+    for r in raw {
+        out.push(FileRow {
+            id: r.try_get("id")?,
+            folder_id: r.try_get("folder_id")?,
+            user_id: r.try_get("user_id")?,
+            name: r.try_get("name")?,
+            blob_hash: r.try_get("blob_hash")?,
+            created_at: r.try_get("created_at")?,
+        });
+    }
+    Ok(out)
+}
+
+/// Looks for a row in the same `(folder_id, user_id)` scope whose
+/// CURRENT name equals `nfc_name`, excluding the row being processed.
+/// The other row may itself be in non-NFC form whose normalized
+/// representation happens to differ from `nfc_name`; the collision
+/// check is intentionally based on stored bytes (matching the
+/// UNIQUE-index semantics that this migration is repairing).
+async fn find_collision(
+    pool: &PgPool,
+    row: &FileRow,
+    nfc_name: &str,
+) -> Result<Option<FileRow>, Box<dyn std::error::Error>> {
+    let result = sqlx::query(
+        "SELECT id, folder_id, user_id, name, blob_hash, created_at
+           FROM storage.files
+          WHERE name = $1
+            AND user_id = $2
+            AND ($3::uuid IS NULL AND folder_id IS NULL
+                 OR folder_id = $3::uuid)
+            AND id <> $4
+            AND NOT is_trashed
+          LIMIT 1",
+    )
+    .bind(nfc_name)
+    .bind(row.user_id)
+    .bind(row.folder_id)
+    .bind(row.id)
+    .fetch_optional(pool)
+    .await?;
+
+    Ok(result.map(|r| FileRow {
+        id: r.get("id"),
+        folder_id: r.get("folder_id"),
+        user_id: r.get("user_id"),
+        name: r.get("name"),
+        blob_hash: r.get("blob_hash"),
+        created_at: r.get("created_at"),
+    }))
+}
+
+/// Finds a free name in the form `{nfc_name}.duplicate` or
+/// `{nfc_name}.duplicate-N` for `N >= 1`, scoped to the row's
+/// `(folder_id, user_id)`. Returns the first candidate that does
+/// not currently exist as a non-trashed row.
+async fn find_free_duplicate_name(
+    pool: &PgPool,
+    row: &FileRow,
+    nfc_name: &str,
+) -> Result<String, Box<dyn std::error::Error>> {
+    let mut suffix: u32 = 0;
+    loop {
+        let candidate = if suffix == 0 {
+            format!("{}.duplicate", nfc_name)
+        } else {
+            format!("{}.duplicate-{}", nfc_name, suffix)
+        };
+
+        let taken: bool = sqlx::query_scalar(
+            "SELECT EXISTS(
+                SELECT 1 FROM storage.files
+                 WHERE name = $1
+                   AND user_id = $2
+                   AND ($3::uuid IS NULL AND folder_id IS NULL
+                        OR folder_id = $3::uuid)
+                   AND id <> $4
+                   AND NOT is_trashed)",
+        )
+        .bind(&candidate)
+        .bind(row.user_id)
+        .bind(row.folder_id)
+        .bind(row.id)
+        .fetch_one(pool)
+        .await?;
+
+        if !taken {
+            return Ok(candidate);
+        }
+        suffix = suffix.saturating_add(1);
+        // Safety bound — should never trigger under realistic data.
+        if suffix > 10_000 {
+            return Err(format!(
+                "Exhausted .duplicate-N suffixes for '{}' in scope (user={}, folder_id={:?})",
+                nfc_name, row.user_id, row.folder_id
+            )
+            .into());
+        }
+    }
+}
+
+/// If the surviving (older) row's stored name is not yet in NFC,
+/// UPDATE it now that the collision has been resolved.
+async fn normalize_survivor_name(
+    pool: &PgPool,
+    survivor: &FileRow,
+    nfc_name: &str,
+) -> Result<(), Box<dyn std::error::Error>> {
+    if survivor.name == nfc_name {
+        return Ok(());
+    }
+    sqlx::query("UPDATE storage.files SET name = $1 WHERE id = $2")
+        .bind(nfc_name)
+        .bind(survivor.id)
+        .execute(pool)
+        .await?;
+    Ok(())
+}
diff --git a/src/domain/entities/file.rs b/src/domain/entities/file.rs
index 57728d4d..f42147f9 100644
--- a/src/domain/entities/file.rs
+++ b/src/domain/entities/file.rs
@@ -1,6 +1,8 @@
 use uuid::Uuid;
 
-use crate::domain::services::path_service::{StoragePath, validate_storage_name};
+use crate::domain::services::path_service::{
+    StoragePath, normalize_storage_name, validate_storage_name,
+};
 
 // Re-export entity errors from the centralized module
 pub use super::entity_errors::{FileError, FileResult};
@@ -21,7 +23,8 @@ pub struct FileParts {
     pub created_at: u64,
     pub modified_at: u64,
     pub owner_id: Option<Uuid>,
-    pub etag: String,
+    /// BLAKE3 content hash. See [`File::content_hash`] for semantics.
+    pub blob_hash: String,
 }
 
 /**
@@ -66,8 +69,14 @@ pub struct File {
     /// Owner user ID (from storage.files.user_id)
     owner_id: Option<Uuid>,
 
-    /// Content-addressable ETag (= blob_hash). Changes on every content write.
-    etag: String,
+    /// BLAKE3 content hash. Stable across renames/moves, changes only
+    /// when the file's content bytes change. Source of truth for both
+    /// content-addressable storage and the HTTP ETag (via
+    /// [`File::etag`]). Exposed publicly via [`File::content_hash`]
+    /// so the REST API can surface it as a distinct concept from the
+    /// ETag (the ETag formula may grow to include `modified_at` etc.,
+    /// but `content_hash` remains the raw hash).
+    blob_hash: String,
 }
 
 // We no longer need this module, now we use a String directly
@@ -85,7 +94,7 @@ impl Default for File {
             created_at: 0,
             modified_at: 0,
             owner_id: None,
-            etag: String::new(),
+            blob_hash: String::new(),
         }
     }
 }
@@ -100,6 +109,7 @@ impl File {
         mime_type: String,
         folder_id: Option<String>,
     ) -> FileResult<Self> {
+        let name = normalize_storage_name(&name);
         if let Err(reason) = validate_storage_name(&name) {
             return Err(FileError::InvalidFileName(format!("{name}: {reason}")));
         }
@@ -123,7 +133,7 @@ impl File {
             created_at: now,
             modified_at: now,
             owner_id: None,
-            etag: String::new(),
+            blob_hash: String::new(),
         })
     }
 
@@ -136,6 +146,7 @@ impl File {
         created_at: u64,
         modified_at: u64,
     ) -> FileResult<Self> {
+        let name = normalize_storage_name(&name);
         if let Err(reason) = validate_storage_name(&name) {
             return Err(FileError::InvalidFileName(format!("{name}: {reason}")));
         }
@@ -154,7 +165,7 @@ impl File {
             created_at,
             modified_at,
             owner_id: None,
-            etag: String::new(),
+            blob_hash: String::new(),
         })
     }
 
@@ -170,7 +181,7 @@ impl File {
         modified_at: u64,
         owner_id: Option<Uuid>,
     ) -> FileResult<Self> {
-        Self::with_timestamps_and_etag(
+        Self::with_timestamps_and_blob_hash(
             id,
             name,
             storage_path,
@@ -185,7 +196,7 @@ impl File {
     }
 
     #[allow(clippy::too_many_arguments)]
-    pub fn with_timestamps_and_etag(
+    pub fn with_timestamps_and_blob_hash(
         id: String,
         name: String,
         storage_path: StoragePath,
@@ -195,8 +206,9 @@ impl File {
         created_at: u64,
         modified_at: u64,
         owner_id: Option<Uuid>,
-        etag: String,
+        blob_hash: String,
     ) -> FileResult<Self> {
+        let name = normalize_storage_name(&name);
         if let Err(reason) = validate_storage_name(&name) {
             return Err(FileError::InvalidFileName(format!("{name}: {reason}")));
         }
@@ -215,7 +227,7 @@ impl File {
             created_at,
             modified_at,
             owner_id,
-            etag,
+            blob_hash,
         })
     }
 
@@ -235,12 +247,67 @@ impl File {
             created_at: self.created_at,
             modified_at: self.modified_at,
             owner_id: self.owner_id,
-            etag: self.etag,
+            blob_hash: self.blob_hash,
         }
     }
 
-    pub fn etag(&self) -> &str {
-        &self.etag
+    /// Raw BLAKE3 content hash — the cryptographic identity of the
+    /// file's bytes. Stable across renames, moves, and metadata
+    /// updates. Changes only when the underlying content changes.
+    ///
+    /// This is **distinct from [`File::etag`]**: the ETag is an HTTP
+    /// cache token that may incorporate non-content signals (mtime,
+    /// permissions, …) in future revisions; `content_hash` is the
+    /// raw hash, suitable for content-addressable URLs, dedup
+    /// verification, and integrity audits. Keep both accessible —
+    /// the API layer can choose to expose `content_hash` even when
+    /// `etag` grows additional inputs.
+    pub fn content_hash(&self) -> &str {
+        &self.blob_hash
+    }
+
+    /// Opaque HTTP ETag string (raw, NOT HTTP-quoted). Handlers wrap
+    /// in `"…"` themselves at the HTTP boundary.
+    ///
+    /// This is a thin instance-method wrapper around
+    /// [`File::compute_etag`] — see that function for the full
+    /// formula, rationale, and the "single source of truth"
+    /// guarantee that lets raw-row listings (`/api/folders/{id}/resources`,
+    /// favorites, trash, recents, REPORT/SEARCH) compute the same
+    /// value without constructing a full `File` entity.
+    pub fn etag(&self) -> String {
+        Self::compute_etag(&self.blob_hash, self.modified_at)
+    }
+
+    /// Pure formula for the file ETag, exposed as a static method so
+    /// listing handlers that operate on raw SQL rows (rather than
+    /// fully-constructed `File` entities) route through the same
+    /// definition.
+    ///
+    /// **Formula**: `{blob_hash[..16]}-{modified_at}`.
+    ///
+    /// - The 16-char BLAKE3 prefix is the content identity (64 bits
+    ///   ≈ 10⁻⁹ collision probability over 10M files).
+    /// - `modified_at` (Unix seconds) catches the `x-oc-mtime`
+    ///   case: NextCloud preserves the client-side mtime on upload,
+    ///   so a "touch-then-resync" of unchanged content still bumps
+    ///   the mtime — without the suffix the ETag wouldn't change
+    ///   and clients would serve stale metadata.
+    /// - When `blob_hash` is shorter than 16 chars (test fixtures,
+    ///   stub entities) the prefix is just the whole value.
+    /// - Folder ETags follow a separate formula — see
+    ///   [`crate::domain::entities::folder::Folder::compute_etag`].
+    ///
+    /// Every handler that emits a file ETag header MUST go through
+    /// this function (directly or via [`File::etag`] /
+    /// `FileDto::etag`) so `GET`, `HEAD`, `PROPFIND`, `PUT`
+    /// response, `MOVE`, and every JSON listing return
+    /// byte-identical values for the same file. Changing the
+    /// formula here changes it everywhere — that is the property
+    /// we want.
+    pub fn compute_etag(blob_hash: &str, modified_at: u64) -> String {
+        let prefix: String = blob_hash.chars().take(16).collect();
+        format!("{}-{}", prefix, modified_at)
     }
 
     // Getters
@@ -298,7 +365,11 @@ impl File {
         // Create storage_path from string
         let storage_path = StoragePath::from_string(&path);
 
-        // Create directly without validation to avoid errors in DTO conversions
+        // Create directly without validation to avoid errors in DTO
+        // conversions. Still NFC-normalize so even DTO-reconstructed
+        // entities maintain the storage invariant.
+        let name = normalize_storage_name(&name);
+
         Self {
             id,
             name,
@@ -310,7 +381,7 @@ impl File {
             created_at,
             modified_at,
             owner_id: None,
-            etag: String::new(),
+            blob_hash: String::new(),
         }
     }
 
@@ -318,6 +389,7 @@ impl File {
 
     /// Creates a new version of the file with updated name
     pub fn with_name(&self, new_name: String) -> FileResult<Self> {
+        let new_name = normalize_storage_name(&new_name);
         if let Err(reason) = validate_storage_name(&new_name) {
             return Err(FileError::InvalidFileName(format!("{new_name}: {reason}")));
         }
@@ -348,7 +420,7 @@ impl File {
             created_at: self.created_at,
             modified_at: now,
             owner_id: self.owner_id,
-            etag: self.etag.clone(),
+            blob_hash: self.blob_hash.clone(),
         })
     }
 
@@ -383,7 +455,7 @@ impl File {
             created_at: self.created_at,
             modified_at: now,
             owner_id: self.owner_id,
-            etag: self.etag.clone(),
+            blob_hash: self.blob_hash.clone(),
         })
     }
 
@@ -405,7 +477,7 @@ impl File {
             created_at: self.created_at,
             modified_at: now,
             owner_id: self.owner_id,
-            etag: self.etag.clone(),
+            blob_hash: self.blob_hash.clone(),
         }
     }
 }
@@ -467,4 +539,77 @@ mod tests {
         assert_eq!(renamed.name(), "newname.txt");
         assert_eq!(renamed.id(), "123"); // The ID does not change
     }
+
+    /// The ETag formula is `{blob_hash[..16]}-{modified_at}`. Two
+    /// fixtures with identical content + mtime must produce
+    /// byte-identical ETags — that's the invariant every handler
+    /// relies on when comparing a cached client ETag against a
+    /// freshly-loaded one.
+    #[test]
+    fn test_etag_combines_blob_hash_prefix_and_mtime() {
+        let file = File::with_timestamps_and_blob_hash(
+            "id-1".to_string(),
+            "file.txt".to_string(),
+            StoragePath::from_string("/file.txt"),
+            42,
+            "text/plain".to_string(),
+            None,
+            1_000,
+            2_000,
+            None,
+            "abcdef0123456789ZZZZZZZZ".to_string(),
+        )
+        .unwrap();
+
+        // content_hash stays raw — full blob hash, no truncation.
+        assert_eq!(file.content_hash(), "abcdef0123456789ZZZZZZZZ");
+        // etag is the 16-char prefix + "-" + mtime.
+        assert_eq!(file.etag(), "abcdef0123456789-2000");
+    }
+
+    /// When the blob hash is shorter than 16 chars (test fixtures,
+    /// stub entities), the prefix degrades to "whatever is there".
+    /// Production blob hashes are always full BLAKE3 hex (64 chars).
+    #[test]
+    fn test_etag_short_blob_hash_uses_full_value() {
+        let file = File::with_timestamps_and_blob_hash(
+            "id-1".to_string(),
+            "file.txt".to_string(),
+            StoragePath::from_string("/file.txt"),
+            42,
+            "text/plain".to_string(),
+            None,
+            1_000,
+            2_000,
+            None,
+            "shorthash".to_string(),
+        )
+        .unwrap();
+
+        assert_eq!(file.etag(), "shorthash-2000");
+    }
+
+    /// `content_hash` is the cryptographic identity of the bytes —
+    /// it must NEVER change because of metadata operations like
+    /// rename. The ETag is allowed to change (because `with_name`
+    /// bumps `modified_at`), but the content hash is not.
+    #[test]
+    fn test_content_hash_stable_across_rename() {
+        let file = File::with_timestamps_and_blob_hash(
+            "id-1".to_string(),
+            "file.txt".to_string(),
+            StoragePath::from_string("/file.txt"),
+            42,
+            "text/plain".to_string(),
+            None,
+            1_000,
+            2_000,
+            None,
+            "stable-content-hash".to_string(),
+        )
+        .unwrap();
+
+        let renamed = file.with_name("renamed.txt".to_string()).unwrap();
+        assert_eq!(renamed.content_hash(), "stable-content-hash");
+    }
 }
diff --git a/src/domain/entities/folder.rs b/src/domain/entities/folder.rs
index d4ebe33c..b08c0c76 100644
--- a/src/domain/entities/folder.rs
+++ b/src/domain/entities/folder.rs
@@ -1,6 +1,8 @@
 use uuid::Uuid;
 
-use crate::domain::services::path_service::{StoragePath, validate_storage_name};
+use crate::domain::services::path_service::{
+    StoragePath, normalize_storage_name, validate_storage_name,
+};
 
 // Re-export entity errors from the centralized module
 pub use super::entity_errors::{FolderError, FolderResult};
@@ -30,8 +32,17 @@ pub struct Folder {
     /// Creation timestamp
     created_at: u64,
 
-    /// Last modification timestamp
+    /// Last modification timestamp of THIS folder row (rename, move,
+    /// metadata change). Does NOT bump when descendants change —
+    /// that signal lives on `tree_modified_at`.
     modified_at: u64,
+
+    /// Latest `modified_at`-equivalent across the entire descendant
+    /// subtree. Bumped by a PostgreSQL trigger on any file or folder
+    /// write under this folder's ltree subtree. Source of the
+    /// HTTP ETag emitted in PROPFIND/GET/HEAD responses — see
+    /// [`Folder::etag`] for the formula and rationale.
+    tree_modified_at: u64,
 }
 
 // We no longer need this module, now we use a String directly
@@ -47,6 +58,7 @@ impl Default for Folder {
             owner_id: None,
             created_at: 0,
             modified_at: 0,
+            tree_modified_at: 0,
         }
     }
 }
@@ -70,6 +82,7 @@ impl Folder {
         parent_id: Option<String>,
         owner_id: Option<Uuid>,
     ) -> FolderResult<Self> {
+        let name = normalize_storage_name(&name);
         // Validate folder name
         if let Err(reason) = validate_storage_name(&name) {
             return Err(FolderError::InvalidFolderName(format!("{name}: {reason}")));
@@ -92,10 +105,15 @@ impl Folder {
             owner_id,
             created_at: now,
             modified_at: now,
+            tree_modified_at: now,
         })
     }
 
-    /// Creates a folder with specific timestamps (for reconstruction)
+    /// Creates a folder with specific timestamps (for reconstruction).
+    /// `tree_modified_at` defaults to `modified_at` — appropriate for
+    /// in-memory construction; database loads should always go via
+    /// [`Folder::with_timestamps_and_tree`] so the rollup value
+    /// reflects DB reality.
     pub fn with_timestamps(
         id: String,
         name: String,
@@ -104,7 +122,7 @@ impl Folder {
         created_at: u64,
         modified_at: u64,
     ) -> FolderResult<Self> {
-        Self::with_timestamps_and_owner(
+        Self::with_timestamps_and_tree(
             id,
             name,
             storage_path,
@@ -112,10 +130,15 @@ impl Folder {
             None,
             created_at,
             modified_at,
+            modified_at,
         )
     }
 
-    /// Creates a folder with specific timestamps and owner (for DB reconstruction)
+    /// Creates a folder with specific timestamps and owner (legacy
+    /// constructor — `tree_modified_at` defaults to `modified_at`).
+    /// Prefer [`Folder::with_timestamps_and_tree`] for DB reconstruction
+    /// so the rollup ETag reflects descendant activity, not just this
+    /// row's own metadata.
     pub fn with_timestamps_and_owner(
         id: String,
         name: String,
@@ -125,12 +148,37 @@ impl Folder {
         created_at: u64,
         modified_at: u64,
     ) -> FolderResult<Self> {
-        // Validate folder name
+        Self::with_timestamps_and_tree(
+            id,
+            name,
+            storage_path,
+            parent_id,
+            owner_id,
+            created_at,
+            modified_at,
+            modified_at,
+        )
+    }
+
+    /// Full constructor used by the PG repository when reading rows.
+    /// `tree_modified_at` comes from the trigger-maintained column on
+    /// `storage.folders` and feeds [`Folder::etag`].
+    #[allow(clippy::too_many_arguments)]
+    pub fn with_timestamps_and_tree(
+        id: String,
+        name: String,
+        storage_path: StoragePath,
+        parent_id: Option<String>,
+        owner_id: Option<Uuid>,
+        created_at: u64,
+        modified_at: u64,
+        tree_modified_at: u64,
+    ) -> FolderResult<Self> {
+        let name = normalize_storage_name(&name);
         if let Err(reason) = validate_storage_name(&name) {
             return Err(FolderError::InvalidFolderName(format!("{name}: {reason}")));
         }
 
-        // Store the path string for serialization compatibility
         let path_string = storage_path.to_string();
 
         Ok(Self {
@@ -142,6 +190,7 @@ impl Folder {
             owner_id,
             created_at,
             modified_at,
+            tree_modified_at,
         })
     }
 
@@ -178,6 +227,54 @@ impl Folder {
         self.owner_id
     }
 
+    /// Latest descendant-write timestamp, maintained by a Postgres
+    /// trigger that walks the ltree ancestor chain on every file or
+    /// folder write inside this folder's subtree. See migration
+    /// `20260625000000_folder_tree_modified_at.sql` for the trigger
+    /// definition.
+    pub fn tree_modified_at(&self) -> u64 {
+        self.tree_modified_at
+    }
+
+    /// Opaque HTTP ETag string (raw, NOT HTTP-quoted). Handlers wrap
+    /// in `"…"` themselves at the HTTP boundary.
+    ///
+    /// Thin instance-method wrapper around [`Folder::compute_etag`]
+    /// — see that function for the formula and the rationale.
+    /// Raw-row listings (favorites, trash, recents, search) call
+    /// the static form so the same formula governs every code path.
+    pub fn etag(&self) -> String {
+        Self::compute_etag(&self.id, self.tree_modified_at)
+    }
+
+    /// Pure formula for the folder ETag, exposed as a static method
+    /// so callers that don't have a fully-constructed `Folder` (raw
+    /// SQL rows in listing handlers, search results, etc.) route
+    /// through the same definition.
+    ///
+    /// **Formula**: `{id[..16]}-{tree_modified_at}`.
+    ///
+    /// - The 16-char UUID prefix gives the folder its identity
+    ///   component — keeps two empty same-mtime folders distinct.
+    /// - `tree_modified_at` (Unix seconds) is the actual signal:
+    ///   bumped by trigger whenever ANY descendant (file or
+    ///   sub-folder, at any depth) is created, modified, deleted,
+    ///   or moved. This is the contract NextCloud's sync engine
+    ///   relies on — "did anything change inside this collection
+    ///   since I last looked?". Until this column existed, the
+    ///   answer was always "no" because the folder UUID never
+    ///   changed; clients had to do periodic deep PROPFIND walks
+    ///   to discover web-uploaded files.
+    /// - Renaming the folder itself does NOT change the etag's
+    ///   identity portion (UUID is stable across renames). The
+    ///   trigger does bump `tree_modified_at` on rename via the
+    ///   folder-side trigger, so the etag still changes — which is
+    ///   correct, the parent collection's listing changed.
+    pub fn compute_etag(id: &str, tree_modified_at: u64) -> String {
+        let prefix: String = id.chars().take(16).collect();
+        format!("{}-{}", prefix, tree_modified_at)
+    }
+
     /// Creates a new Folder instance from a DTO
     /// This function is primarily for conversions in batch handlers
     pub fn from_dto(
@@ -191,7 +288,14 @@ impl Folder {
         // Create storage_path from the string
         let storage_path = StoragePath::from_string(&path);
 
-        // Create directly without validation to avoid errors in DTO conversions
+        // Create directly without validation to avoid errors in DTO
+        // conversions. Still NFC-normalize so DTO-reconstructed
+        // entities maintain the storage invariant.
+        // `tree_modified_at` defaults to `modified_at`: DTO
+        // round-trips lose the real rollup signal, so callers that
+        // need a freshly-rolled-up etag must reload from the
+        // repository.
+        let name = normalize_storage_name(&name);
         Self {
             id,
             name,
@@ -201,6 +305,7 @@ impl Folder {
             owner_id: None,
             created_at,
             modified_at,
+            tree_modified_at: modified_at,
         }
     }
 
@@ -208,6 +313,7 @@ impl Folder {
 
     /// Creates a new version of the folder with updated name
     pub fn with_name(&self, new_name: String) -> FolderResult<Self> {
+        let new_name = normalize_storage_name(&new_name);
         if let Err(reason) = validate_storage_name(&new_name) {
             return Err(FolderError::InvalidFolderName(format!(
                 "{new_name}: {reason}"
@@ -238,6 +344,10 @@ impl Folder {
             owner_id: self.owner_id,
             created_at: self.created_at,
             modified_at: now,
+            // Renaming bumps both self and descendant rollup —
+            // ancestors' listings now show a new name, so the
+            // collection has materially changed.
+            tree_modified_at: now,
         })
     }
 
@@ -270,6 +380,7 @@ impl Folder {
             owner_id: self.owner_id,
             created_at: self.created_at,
             modified_at: now,
+            tree_modified_at: now,
         })
     }
 
@@ -343,4 +454,90 @@ mod tests {
         assert_eq!(renamed.name(), "new_name");
         assert_eq!(renamed.id(), "123"); // The ID doesn't change
     }
+
+    /// The folder ETag is `{id[..16]}-{tree_modified_at}`. Two
+    /// fixtures with identical id-prefix + tree_modified_at must
+    /// produce byte-identical ETags — that's what NC's incremental
+    /// sync relies on across PROPFIND cycles.
+    #[test]
+    fn test_etag_combines_id_prefix_and_tree_modified_at() {
+        let folder = Folder::with_timestamps_and_tree(
+            "0123456789abcdefZZZZZZZZ".to_string(),
+            "folder".to_string(),
+            StoragePath::from_string("/folder"),
+            None,
+            None,
+            1_000,
+            2_000,
+            5_000,
+        )
+        .unwrap();
+
+        assert_eq!(folder.tree_modified_at(), 5_000);
+        assert_eq!(folder.etag(), "0123456789abcdef-5000");
+    }
+
+    /// Two folders with the same `tree_modified_at` but different
+    /// IDs must NOT collide on ETag — the id prefix is the identity
+    /// portion that keeps them distinct.
+    #[test]
+    fn test_etag_distinct_folders_same_tree_mtime() {
+        let a = Folder::with_timestamps_and_tree(
+            "aaaaaaaaaaaaaaaaZZZZZZZZ".to_string(),
+            "a".to_string(),
+            StoragePath::from_string("/a"),
+            None,
+            None,
+            0,
+            0,
+            42,
+        )
+        .unwrap();
+        let b = Folder::with_timestamps_and_tree(
+            "bbbbbbbbbbbbbbbbZZZZZZZZ".to_string(),
+            "b".to_string(),
+            StoragePath::from_string("/b"),
+            None,
+            None,
+            0,
+            0,
+            42,
+        )
+        .unwrap();
+
+        assert_ne!(a.etag(), b.etag());
+    }
+
+    /// `tree_modified_at` is the actual change-detection signal —
+    /// the trigger bumps it for descendant writes. Renaming the
+    /// folder bumps both `modified_at` and `tree_modified_at`
+    /// (the parent collection's listing changed), and the etag
+    /// must reflect that — otherwise NC won't notice the rename.
+    #[test]
+    fn test_etag_changes_when_tree_modified_at_changes() {
+        let folder_a = Folder::with_timestamps_and_tree(
+            "abcd1234efgh5678ZZZZZZZZ".to_string(),
+            "folder".to_string(),
+            StoragePath::from_string("/folder"),
+            None,
+            None,
+            1_000,
+            2_000,
+            3_000,
+        )
+        .unwrap();
+        let folder_b = Folder::with_timestamps_and_tree(
+            "abcd1234efgh5678ZZZZZZZZ".to_string(),
+            "folder".to_string(),
+            StoragePath::from_string("/folder"),
+            None,
+            None,
+            1_000,
+            2_000,
+            4_000,
+        )
+        .unwrap();
+
+        assert_ne!(folder_a.etag(), folder_b.etag());
+    }
 }
diff --git a/src/domain/services/path_service.rs b/src/domain/services/path_service.rs
index 5c147ba7..70fa4b4c 100644
--- a/src/domain/services/path_service.rs
+++ b/src/domain/services/path_service.rs
@@ -5,6 +5,29 @@
 //! infrastructure/services/path_service.rs because it has file system dependencies.
 
 use std::path::PathBuf;
+use unicode_normalization::UnicodeNormalization;
+
+/// NFC-normalize a single file or folder name component.
+///
+/// The storage layer (PostgreSQL `storage.files.name` and
+/// `storage.folders.name`) compares bytes literally — there is no
+/// Unicode-aware collation in either UNIQUE index. macOS APFS stores
+/// filenames in NFD (decomposed: `é` = `e` + U+0301), while browsers
+/// and most other clients post NFC (`é` = U+00E9). Without
+/// normalization, the same logical filename can land as two distinct
+/// rows: one from a web upload, one from a NextCloud desktop client
+/// re-upload of the round-tripped name. The UNIQUE index does not
+/// catch it because the bytes differ.
+///
+/// This function is called at every name-receiving boundary (entity
+/// constructors, repository path lookups) so the database invariant
+/// becomes "every stored name is NFC". A one-shot migration
+/// (`migrate-nfc-filenames`) cleans up rows that pre-date this rule.
+///
+/// Pure function — no I/O, allocates one `String`.
+pub fn normalize_storage_name(name: &str) -> String {
+    name.nfc().collect()
+}
 
 /// Validates a single file or folder name component.
 ///
@@ -251,4 +274,43 @@ mod tests {
         assert!(!path.segments().contains(&"..".to_string()));
         assert!(!path.segments().contains(&".".to_string()));
     }
+
+    // ── NFC normalization tests ─────────────────────────────────
+
+    /// Plain ASCII names must round-trip identical bytes.
+    #[test]
+    fn test_normalize_ascii_unchanged() {
+        assert_eq!(normalize_storage_name("file.txt"), "file.txt");
+        assert_eq!(normalize_storage_name("My Documents"), "My Documents");
+    }
+
+    /// The macOS APFS / NextCloud-desktop pathological case: `é`
+    /// decomposed as `e` + combining acute (U+0301). Stored bytes
+    /// `65 cc 81` collapse to NFC `c3 a9`.
+    #[test]
+    fn test_normalize_nfd_to_nfc() {
+        let nfd = "caf\u{0065}\u{0301}";
+        let nfc = "caf\u{00E9}";
+        assert_ne!(nfd.as_bytes(), nfc.as_bytes());
+        assert_eq!(normalize_storage_name(nfd), nfc);
+    }
+
+    /// Already-NFC input must round-trip unchanged. This is the
+    /// idempotence property the boundary normalization relies on.
+    #[test]
+    fn test_normalize_nfc_idempotent() {
+        let nfc = "Capture d\u{2019}\u{00E9}cran.png";
+        assert_eq!(normalize_storage_name(nfc), nfc);
+        // And applying twice is the same as once.
+        assert_eq!(normalize_storage_name(&normalize_storage_name(nfc)), nfc);
+    }
+
+    /// Multi-codepoint NFD sequences (combining acute + grave +
+    /// typographic apostrophe) all converge to a single NFC form.
+    #[test]
+    fn test_normalize_mixed_accents() {
+        let nfd = "Capture d\u{2019}\u{0065}\u{0301}cran a\u{0300}.png";
+        let nfc = "Capture d\u{2019}\u{00E9}cran \u{00E0}.png";
+        assert_eq!(normalize_storage_name(nfd), nfc);
+    }
 }
diff --git a/src/infrastructure/repositories/pg/favorites_pg_repository.rs b/src/infrastructure/repositories/pg/favorites_pg_repository.rs
index 03d00a9e..3020722b 100644
--- a/src/infrastructure/repositories/pg/favorites_pg_repository.rs
+++ b/src/infrastructure/repositories/pg/favorites_pg_repository.rs
@@ -310,6 +310,7 @@ impl FavoritesRepositoryPort for FavoritesPgRepository {
         fld.created_at                   AS resource_created_at,
         fld.updated_at                   AS modified_at,
         fld.user_id                      AS owner_id,
+        NULL::text                       AS blob_hash,
         (fld.user_id = $1::uuid)         AS is_owner,
         uf.created_at                    AS favorited_at,
         fld.path::text                   AS resource_path,
@@ -332,6 +333,7 @@ impl FavoritesRepositoryPort for FavoritesPgRepository {
         f.created_at                     AS resource_created_at,
         f.updated_at                     AS modified_at,
         f.user_id                        AS owner_id,
+        f.blob_hash,
         (f.user_id = $1::uuid)           AS is_owner,
         uf.created_at                    AS favorited_at,
         COALESCE(pfld.path::text || '/' || f.name, f.name) AS resource_path,
@@ -574,6 +576,7 @@ LIMIT $6"
                     resource_created_at: row.get("resource_created_at"),
                     modified_at: row.get("modified_at"),
                     owner_id: row.get("owner_id"),
+                    blob_hash: row.try_get("blob_hash").ok(),
                     is_owner: row.try_get("is_owner").unwrap_or(false),
                     favorited_at: row.get("favorited_at"),
                     path: row.try_get("resource_path").ok(),
diff --git a/src/infrastructure/repositories/pg/file_blob_read_repository.rs b/src/infrastructure/repositories/pg/file_blob_read_repository.rs
index 8bb55f53..3077001a 100644
--- a/src/infrastructure/repositories/pg/file_blob_read_repository.rs
+++ b/src/infrastructure/repositories/pg/file_blob_read_repository.rs
@@ -131,11 +131,11 @@ impl FileBlobReadRepository {
         mime_type: String,
         created_at: i64,
         modified_at: i64,
-        etag: String,
+        blob_hash: String,
         owner_id: Option<Uuid>,
     ) -> Result<File, DomainError> {
         let storage_path = Self::make_file_path(folder_path.as_deref(), &name);
-        File::with_timestamps_and_etag(
+        File::with_timestamps_and_blob_hash(
             id,
             name,
             storage_path,
@@ -145,7 +145,7 @@ impl FileBlobReadRepository {
             created_at as u64,
             modified_at as u64,
             owner_id,
-            etag,
+            blob_hash,
         )
         .map_err(|e| DomainError::internal_error("FileBlobRead", format!("entity: {e}")))
     }
@@ -226,9 +226,9 @@ impl FileBlobReadRepository {
         let mut files = Vec::with_capacity(rows.len());
         let mut sort_dates = Vec::with_capacity(rows.len());
 
-        for (id, name, fid, fpath, size, mime, ca, ma, etag, uid, sd) in rows {
+        for (id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid, sd) in rows {
             files.push(Self::row_to_file(
-                id, name, fid, fpath, size, mime, ca, ma, etag, uid,
+                id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid,
             )?);
             sort_dates.push(sd);
         }
@@ -410,9 +410,11 @@ impl FileReadPort for FileBlobReadRepository {
         .map_err(|e| DomainError::internal_error("FileBlobRead", format!("list: {e}")))?;
 
         rows.into_iter()
-            .map(|(id, name, fid, fpath, size, mime, ca, ma, etag, uid)| {
-                Self::row_to_file(id, name, fid, fpath, size, mime, ca, ma, etag, uid)
-            })
+            .map(
+                |(id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid)| {
+                    Self::row_to_file(id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid)
+                },
+            )
             .collect()
     }
 
@@ -466,9 +468,11 @@ impl FileReadPort for FileBlobReadRepository {
         .map_err(|e| DomainError::internal_error("FileBlobRead", format!("list_for_owner: {e}")))?;
 
         rows.into_iter()
-            .map(|(id, name, fid, fpath, size, mime, ca, ma, etag, uid)| {
-                Self::row_to_file(id, name, fid, fpath, size, mime, ca, ma, etag, uid)
-            })
+            .map(
+                |(id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid)| {
+                    Self::row_to_file(id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid)
+                },
+            )
             .collect()
     }
 
@@ -532,9 +536,11 @@ impl FileReadPort for FileBlobReadRepository {
         .map_err(|e| DomainError::internal_error("FileBlobRead", format!("list_batch: {e}")))?;
 
         rows.into_iter()
-            .map(|(id, name, fid, fpath, size, mime, ca, ma, etag, uid)| {
-                Self::row_to_file(id, name, fid, fpath, size, mime, ca, ma, etag, uid)
-            })
+            .map(
+                |(id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid)| {
+                    Self::row_to_file(id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid)
+                },
+            )
             .collect()
     }
 
@@ -598,9 +604,11 @@ impl FileReadPort for FileBlobReadRepository {
         })?;
 
         rows.into_iter()
-            .map(|(id, name, fid, fpath, size, mime, ca, ma, etag, uid)| {
-                Self::row_to_file(id, name, fid, fpath, size, mime, ca, ma, etag, uid)
-            })
+            .map(
+                |(id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid)| {
+                    Self::row_to_file(id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid)
+                },
+            )
             .collect()
     }
 
@@ -699,8 +707,14 @@ impl FileReadPort for FileBlobReadRepository {
             return Ok(None);
         }
 
-        // Last segment is the filename, preceding segments are the folder path
-        let filename = segments[segments.len() - 1];
+        // Last segment is the filename, preceding segments are the
+        // folder path. NFC-normalize the filename so a NextCloud
+        // client's NFD-encoded path still hits the NFC row stored
+        // by a web upload — see `normalize_storage_name` for the
+        // full rationale.
+        let filename = crate::domain::services::path_service::normalize_storage_name(
+            segments[segments.len() - 1],
+        );
         let folder_path = segments[..segments.len() - 1].join("/");
 
         let row = if folder_path.is_empty() {
@@ -815,9 +829,9 @@ impl FileReadPort for FileBlobReadRepository {
             while let Some(row) = row_stream.try_next().await.map_err(|e| {
                 DomainError::internal_error("FileBlobRead", format!("subtree stream: {e}"))
             })? {
-                let (id, name, fid, fpath, size, mime, ca, ma, etag, uid) = row;
+                let (id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid) = row;
                 let file = FileBlobReadRepository::row_to_file(
-                    id, name, fid, fpath, size, mime, ca, ma, etag, uid,
+                    id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid,
                 )?;
                 yield file;
             }
@@ -930,8 +944,8 @@ impl FileReadPort for FileBlobReadRepository {
         let files = rows
             .into_iter()
             .map(
-                |(id, name, fid, fpath, size, mime, ca, ma, etag, uid, _total)| {
-                    Self::row_to_file(id, name, fid, fpath, size, mime, ca, ma, etag, uid)
+                |(id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid, _total)| {
+                    Self::row_to_file(id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid)
                 },
             )
             .collect::<Result<Vec<_>, _>>()
@@ -1116,8 +1130,8 @@ impl FileReadPort for FileBlobReadRepository {
         let files = rows
             .into_iter()
             .map(
-                |(id, name, fid, fpath, size, mime, ca, ma, etag, uid, _total)| {
-                    Self::row_to_file(id, name, fid, fpath, size, mime, ca, ma, etag, uid)
+                |(id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid, _total)| {
+                    Self::row_to_file(id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid)
                 },
             )
             .collect::<Result<Vec<_>, _>>()
@@ -1212,9 +1226,11 @@ impl FileReadPort for FileBlobReadRepository {
         .map_err(|e| DomainError::internal_error("FileBlobRead", format!("suggest: {e}")))?;
 
         rows.into_iter()
-            .map(|(id, name, fid, fpath, size, mime, ca, ma, etag, uid)| {
-                Self::row_to_file(id, name, fid, fpath, size, mime, ca, ma, etag, uid)
-            })
+            .map(
+                |(id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid)| {
+                    Self::row_to_file(id, name, fid, fpath, size, mime, ca, ma, blob_hash, uid)
+                },
+            )
             .collect()
     }
 }
diff --git a/src/infrastructure/repositories/pg/file_blob_write_repository.rs b/src/infrastructure/repositories/pg/file_blob_write_repository.rs
index 3bc1a9bd..7819f939 100644
--- a/src/infrastructure/repositories/pg/file_blob_write_repository.rs
+++ b/src/infrastructure/repositories/pg/file_blob_write_repository.rs
@@ -101,10 +101,10 @@ impl FileBlobWriteRepository {
         created_at: i64,
         modified_at: i64,
         owner_id: Option<Uuid>,
-        etag: String,
+        blob_hash: String,
     ) -> Result<File, DomainError> {
         let storage_path = Self::make_file_path(folder_path.as_deref(), &name);
-        File::with_timestamps_and_etag(
+        File::with_timestamps_and_blob_hash(
             id,
             name,
             storage_path,
@@ -114,7 +114,7 @@ impl FileBlobWriteRepository {
             created_at as u64,
             modified_at as u64,
             owner_id,
-            etag,
+            blob_hash,
         )
         .map_err(|e| DomainError::internal_error("FileBlobWrite", format!("entity: {e}")))
     }
diff --git a/src/infrastructure/repositories/pg/folder_db_repository.rs b/src/infrastructure/repositories/pg/folder_db_repository.rs
index 508370c6..ea6b3466 100644
--- a/src/infrastructure/repositories/pg/folder_db_repository.rs
+++ b/src/infrastructure/repositories/pg/folder_db_repository.rs
@@ -20,10 +20,25 @@ use crate::domain::services::authorization::ResourceKind;
 use crate::domain::services::path_service::StoragePath;
 
 /// Type alias for folder metadata rows from SQL queries.
-type FolderRow = (String, String, String, Option<String>, Uuid, i64, i64);
+/// Tuple order: id, name, path, parent_id, user_id, created_at,
+/// modified_at, tree_modified_at. The trailing `tree_modified_at`
+/// feeds [`Folder::etag`] — every SELECT here must include
+/// `EXTRACT(EPOCH FROM tree_modified_at)::bigint`.
+type FolderRow = (String, String, String, Option<String>, Uuid, i64, i64, i64);
 
-/// Type alias for paginated folder rows (includes total_count).
-type FolderRowPaginated = (String, String, String, Option<String>, Uuid, i64, i64, i64);
+/// Type alias for paginated folder rows (includes total_count as
+/// the last element after `tree_modified_at`).
+type FolderRowPaginated = (
+    String,
+    String,
+    String,
+    Option<String>,
+    Uuid,
+    i64,
+    i64,
+    i64,
+    i64,
+);
 
 /// Type alias for folder rows with optional user_id.
 type FolderRowOptUser = (
@@ -34,6 +49,7 @@ type FolderRowOptUser = (
     Option<Uuid>,
     i64,
     i64,
+    i64,
 );
 
 /// PostgreSQL-backed folder repository.
@@ -68,6 +84,7 @@ impl FolderDbRepository {
     ///
     /// The `path` comes directly from the materialized `path` column — no
     /// extra queries needed.
+    #[allow(clippy::too_many_arguments)]
     fn row_to_folder(
         id: String,
         name: String,
@@ -76,9 +93,10 @@ impl FolderDbRepository {
         user_id: Option<Uuid>,
         created_at: i64,
         modified_at: i64,
+        tree_modified_at: i64,
     ) -> Result<Folder, DomainError> {
         let storage_path = StoragePath::from_string(&path);
-        Folder::with_timestamps_and_owner(
+        Folder::with_timestamps_and_tree(
             id,
             name,
             storage_path,
@@ -86,6 +104,7 @@ impl FolderDbRepository {
             user_id,
             created_at as u64,
             modified_at as u64,
+            tree_modified_at as u64,
         )
         .map_err(|e| DomainError::internal_error("FolderDb", format!("entity: {e}")))
     }
@@ -116,14 +135,15 @@ impl FolderRepository for FolderDbRepository {
             ));
         };
 
-        let row = sqlx::query_as::<_, (String, String, i64, i64)>(
+        let row = sqlx::query_as::<_, (String, String, i64, i64, i64)>(
             r#"
             INSERT INTO storage.folders (name, parent_id, user_id)
             VALUES ($1, $2::uuid, $3)
             RETURNING id::text,
                       path,
                       EXTRACT(EPOCH FROM created_at)::bigint,
-                      EXTRACT(EPOCH FROM updated_at)::bigint
+                      EXTRACT(EPOCH FROM updated_at)::bigint,
+                      EXTRACT(EPOCH FROM tree_modified_at)::bigint
             "#,
         )
         .bind(&name)
@@ -143,15 +163,25 @@ impl FolderRepository for FolderDbRepository {
             DomainError::internal_error("FolderDb", format!("insert: {e}"))
         })?;
 
-        Self::row_to_folder(row.0, name, row.1, parent_id, Some(user_id), row.2, row.3)
+        Self::row_to_folder(
+            row.0,
+            name,
+            row.1,
+            parent_id,
+            Some(user_id),
+            row.2,
+            row.3,
+            row.4,
+        )
     }
 
     async fn get_folder(&self, id: &str) -> Result<Folder, DomainError> {
-        let row = sqlx::query_as::<_, (String, String, String, Option<String>, Uuid, i64, i64)>(
+        let row = sqlx::query_as::<_, FolderRow>(
             r#"
             SELECT id::text, name, path, parent_id::text, user_id,
                    EXTRACT(EPOCH FROM created_at)::bigint,
-                   EXTRACT(EPOCH FROM updated_at)::bigint
+                   EXTRACT(EPOCH FROM updated_at)::bigint,
+                   EXTRACT(EPOCH FROM tree_modified_at)::bigint
               FROM storage.folders
              WHERE id = $1::uuid AND NOT is_trashed
             "#,
@@ -162,7 +192,7 @@ impl FolderRepository for FolderDbRepository {
         .map_err(|e| DomainError::internal_error("FolderDb", format!("get: {e}")))?
         .ok_or_else(|| DomainError::not_found("Folder", id))?;
 
-        Self::row_to_folder(row.0, row.1, row.2, row.3, Some(row.4), row.5, row.6)
+        Self::row_to_folder(row.0, row.1, row.2, row.3, Some(row.4), row.5, row.6, row.7)
     }
 
     async fn get_folder_by_path(&self, storage_path: &StoragePath) -> Result<Folder, DomainError> {
@@ -174,11 +204,12 @@ impl FolderRepository for FolderDbRepository {
             return Err(DomainError::not_found("Folder", "empty path"));
         }
 
-        let row = sqlx::query_as::<_, (String, String, String, Option<String>, Uuid, i64, i64)>(
+        let row = sqlx::query_as::<_, FolderRow>(
             r#"
             SELECT id::text, name, path, parent_id::text, user_id,
                    EXTRACT(EPOCH FROM created_at)::bigint,
-                   EXTRACT(EPOCH FROM updated_at)::bigint
+                   EXTRACT(EPOCH FROM updated_at)::bigint,
+                       EXTRACT(EPOCH FROM tree_modified_at)::bigint
               FROM storage.folders
              WHERE path = $1 AND NOT is_trashed
             "#,
@@ -189,7 +220,7 @@ impl FolderRepository for FolderDbRepository {
         .map_err(|e| DomainError::internal_error("FolderDb", format!("path lookup: {e}")))?
         .ok_or_else(|| DomainError::not_found("Folder", lookup))?;
 
-        Self::row_to_folder(row.0, row.1, row.2, row.3, Some(row.4), row.5, row.6)
+        Self::row_to_folder(row.0, row.1, row.2, row.3, Some(row.4), row.5, row.6, row.7)
     }
 
     #[allow(clippy::type_complexity)]
@@ -199,7 +230,8 @@ impl FolderRepository for FolderDbRepository {
                 r#"
                 SELECT id::text, name, path, parent_id::text, user_id,
                        EXTRACT(EPOCH FROM created_at)::bigint,
-                       EXTRACT(EPOCH FROM updated_at)::bigint
+                       EXTRACT(EPOCH FROM updated_at)::bigint,
+                       EXTRACT(EPOCH FROM tree_modified_at)::bigint
                   FROM storage.folders
                  WHERE parent_id = $1::uuid AND NOT is_trashed
                  ORDER BY name
@@ -213,7 +245,8 @@ impl FolderRepository for FolderDbRepository {
                 r#"
                 SELECT id::text, name, path, parent_id::text, user_id,
                        EXTRACT(EPOCH FROM created_at)::bigint,
-                       EXTRACT(EPOCH FROM updated_at)::bigint
+                       EXTRACT(EPOCH FROM updated_at)::bigint,
+                       EXTRACT(EPOCH FROM tree_modified_at)::bigint
                   FROM storage.folders
                  WHERE parent_id IS NULL AND NOT is_trashed
                  ORDER BY name
@@ -225,8 +258,8 @@ impl FolderRepository for FolderDbRepository {
         .map_err(|e| DomainError::internal_error("FolderDb", format!("list: {e}")))?;
 
         rows.into_iter()
-            .map(|(id, name, path, pid, uid, ca, ma)| {
-                Self::row_to_folder(id, name, path, pid, Some(uid), ca, ma)
+            .map(|(id, name, path, pid, uid, ca, ma, tma)| {
+                Self::row_to_folder(id, name, path, pid, Some(uid), ca, ma, tma)
             })
             .collect()
     }
@@ -242,7 +275,8 @@ impl FolderRepository for FolderDbRepository {
                 r#"
                 SELECT id::text, name, path, parent_id::text, user_id,
                        EXTRACT(EPOCH FROM created_at)::bigint,
-                       EXTRACT(EPOCH FROM updated_at)::bigint
+                       EXTRACT(EPOCH FROM updated_at)::bigint,
+                       EXTRACT(EPOCH FROM tree_modified_at)::bigint
                   FROM storage.folders
                  WHERE parent_id = $1::uuid AND user_id = $2 AND NOT is_trashed
                  ORDER BY name
@@ -257,7 +291,8 @@ impl FolderRepository for FolderDbRepository {
                 r#"
                 SELECT id::text, name, path, parent_id::text, user_id,
                        EXTRACT(EPOCH FROM created_at)::bigint,
-                       EXTRACT(EPOCH FROM updated_at)::bigint
+                       EXTRACT(EPOCH FROM updated_at)::bigint,
+                       EXTRACT(EPOCH FROM tree_modified_at)::bigint
                   FROM storage.folders
                  WHERE parent_id IS NULL AND user_id = $1 AND NOT is_trashed
                  ORDER BY name
@@ -270,8 +305,8 @@ impl FolderRepository for FolderDbRepository {
         .map_err(|e| DomainError::internal_error("FolderDb", format!("list_by_owner: {e}")))?;
 
         rows.into_iter()
-            .map(|(id, name, path, pid, uid, ca, ma)| {
-                Self::row_to_folder(id, name, path, pid, Some(uid), ca, ma)
+            .map(|(id, name, path, pid, uid, ca, ma, tma)| {
+                Self::row_to_folder(id, name, path, pid, Some(uid), ca, ma, tma)
             })
             .collect()
     }
@@ -293,6 +328,7 @@ impl FolderRepository for FolderDbRepository {
                 SELECT id::text, name, path, parent_id::text, user_id,
                        EXTRACT(EPOCH FROM created_at)::bigint,
                        EXTRACT(EPOCH FROM updated_at)::bigint,
+                       EXTRACT(EPOCH FROM tree_modified_at)::bigint,
                        COUNT(*) OVER() AS total_count
                   FROM storage.folders
                  WHERE parent_id = $1::uuid AND NOT is_trashed
@@ -311,6 +347,7 @@ impl FolderRepository for FolderDbRepository {
                 SELECT id::text, name, path, parent_id::text, user_id,
                        EXTRACT(EPOCH FROM created_at)::bigint,
                        EXTRACT(EPOCH FROM updated_at)::bigint,
+                       EXTRACT(EPOCH FROM tree_modified_at)::bigint,
                        COUNT(*) OVER() AS total_count
                   FROM storage.folders
                  WHERE parent_id IS NULL AND NOT is_trashed
@@ -327,15 +364,15 @@ impl FolderRepository for FolderDbRepository {
 
         // total_count is identical in every row; 0 when the result set is empty.
         let total = if include_total {
-            Some(rows.first().map_or(0, |r| r.7) as usize)
+            Some(rows.first().map_or(0, |r| r.8) as usize)
         } else {
             None
         };
 
         let folders: Result<Vec<Folder>, DomainError> = rows
             .into_iter()
-            .map(|(id, name, path, pid, uid, ca, ma, _total)| {
-                Self::row_to_folder(id, name, path, pid, Some(uid), ca, ma)
+            .map(|(id, name, path, pid, uid, ca, ma, tma, _total)| {
+                Self::row_to_folder(id, name, path, pid, Some(uid), ca, ma, tma)
             })
             .collect();
         Ok((folders?, total))
@@ -358,6 +395,7 @@ impl FolderRepository for FolderDbRepository {
                 SELECT id::text, name, path, parent_id::text, user_id,
                        EXTRACT(EPOCH FROM created_at)::bigint,
                        EXTRACT(EPOCH FROM updated_at)::bigint,
+                       EXTRACT(EPOCH FROM tree_modified_at)::bigint,
                        COUNT(*) OVER() AS total_count
                   FROM storage.folders
                  WHERE parent_id = $1::uuid AND user_id = $2 AND NOT is_trashed
@@ -377,6 +415,7 @@ impl FolderRepository for FolderDbRepository {
                 SELECT id::text, name, path, parent_id::text, user_id,
                        EXTRACT(EPOCH FROM created_at)::bigint,
                        EXTRACT(EPOCH FROM updated_at)::bigint,
+                       EXTRACT(EPOCH FROM tree_modified_at)::bigint,
                        COUNT(*) OVER() AS total_count
                   FROM storage.folders
                  WHERE parent_id IS NULL AND user_id = $1 AND NOT is_trashed
@@ -393,15 +432,15 @@ impl FolderRepository for FolderDbRepository {
         .map_err(|e| DomainError::internal_error("FolderDb", format!("paginate_by_owner: {e}")))?;
 
         let total = if include_total {
-            Some(rows.first().map_or(0, |r| r.7) as usize)
+            Some(rows.first().map_or(0, |r| r.8) as usize)
         } else {
             None
         };
 
         let folders: Result<Vec<Folder>, DomainError> = rows
             .into_iter()
-            .map(|(id, name, path, pid, uid, ca, ma, _total)| {
-                Self::row_to_folder(id, name, path, pid, Some(uid), ca, ma)
+            .map(|(id, name, path, pid, uid, ca, ma, tma, _total)| {
+                Self::row_to_folder(id, name, path, pid, Some(uid), ca, ma, tma)
             })
             .collect();
         Ok((folders?, total))
@@ -411,14 +450,15 @@ impl FolderRepository for FolderDbRepository {
         // The BEFORE UPDATE trigger recomputes path/lpath for this row;
         // the AFTER UPDATE cascade trigger then batch-updates all
         // descendants in a single UPDATE using the GiST lpath index.
-        let row = sqlx::query_as::<_, (String, String, String, Option<String>, Uuid, i64, i64)>(
+        let row = sqlx::query_as::<_, FolderRow>(
             r#"
             UPDATE storage.folders
                SET name = $1, updated_at = NOW()
              WHERE id = $2::uuid AND NOT is_trashed
             RETURNING id::text, name, path, parent_id::text, user_id,
                       EXTRACT(EPOCH FROM created_at)::bigint,
-                      EXTRACT(EPOCH FROM updated_at)::bigint
+                      EXTRACT(EPOCH FROM updated_at)::bigint,
+                       EXTRACT(EPOCH FROM tree_modified_at)::bigint
             "#,
         )
         .bind(&new_name)
@@ -435,7 +475,7 @@ impl FolderRepository for FolderDbRepository {
         })?
         .ok_or_else(|| DomainError::not_found("Folder", id))?;
 
-        Self::row_to_folder(row.0, row.1, row.2, row.3, Some(row.4), row.5, row.6)
+        Self::row_to_folder(row.0, row.1, row.2, row.3, Some(row.4), row.5, row.6, row.7)
     }
 
     async fn move_folder(
@@ -446,14 +486,15 @@ impl FolderRepository for FolderDbRepository {
         // The BEFORE UPDATE trigger recomputes path/lpath for this row;
         // the AFTER UPDATE cascade trigger then batch-updates all
         // descendants in a single UPDATE using the GiST lpath index.
-        let row = sqlx::query_as::<_, (String, String, String, Option<String>, Uuid, i64, i64)>(
+        let row = sqlx::query_as::<_, FolderRow>(
             r#"
             UPDATE storage.folders
                SET parent_id = $1::uuid, updated_at = NOW()
              WHERE id = $2::uuid AND NOT is_trashed
             RETURNING id::text, name, path, parent_id::text, user_id,
                       EXTRACT(EPOCH FROM created_at)::bigint,
-                      EXTRACT(EPOCH FROM updated_at)::bigint
+                      EXTRACT(EPOCH FROM updated_at)::bigint,
+                       EXTRACT(EPOCH FROM tree_modified_at)::bigint
             "#,
         )
         .bind(new_parent_id)
@@ -463,7 +504,7 @@ impl FolderRepository for FolderDbRepository {
         .map_err(|e| DomainError::internal_error("FolderDb", format!("move: {e}")))?
         .ok_or_else(|| DomainError::not_found("Folder", id))?;
 
-        Self::row_to_folder(row.0, row.1, row.2, row.3, Some(row.4), row.5, row.6)
+        Self::row_to_folder(row.0, row.1, row.2, row.3, Some(row.4), row.5, row.6, row.7)
     }
 
     async fn delete_folder(&self, id: &str) -> Result<(), DomainError> {
@@ -622,7 +663,7 @@ impl FolderRepository for FolderDbRepository {
     }
 
     async fn create_home_folder(&self, user_id: Uuid, name: String) -> Result<Folder, DomainError> {
-        let row = sqlx::query_as::<_, (String, String, i64, i64)>(
+        let row = sqlx::query_as::<_, (String, String, i64, i64, i64)>(
             r#"
             INSERT INTO storage.folders (name, parent_id, user_id)
             VALUES ($1, NULL, $2)
@@ -630,7 +671,8 @@ impl FolderRepository for FolderDbRepository {
             RETURNING id::text,
                       path,
                       EXTRACT(EPOCH FROM created_at)::bigint,
-                      EXTRACT(EPOCH FROM updated_at)::bigint
+                      EXTRACT(EPOCH FROM updated_at)::bigint,
+                       EXTRACT(EPOCH FROM tree_modified_at)::bigint
             "#,
         )
         .bind(&name)
@@ -640,17 +682,18 @@ impl FolderRepository for FolderDbRepository {
         .map_err(|e| DomainError::internal_error("FolderDb", format!("home folder: {e}")))?;
 
         match row {
-            Some((id, path, ca, ma)) => {
-                Self::row_to_folder(id, name.clone(), path, None, Some(user_id), ca, ma)
+            Some((id, path, ca, ma, tma)) => {
+                Self::row_to_folder(id, name.clone(), path, None, Some(user_id), ca, ma, tma)
             }
             None => {
                 // Already exists — fetch it
-                let existing = sqlx::query_as::<_, (String, String, i64, i64)>(
+                let existing = sqlx::query_as::<_, (String, String, i64, i64, i64)>(
                     r#"
                     SELECT id::text,
                            path,
                            EXTRACT(EPOCH FROM created_at)::bigint,
-                           EXTRACT(EPOCH FROM updated_at)::bigint
+                           EXTRACT(EPOCH FROM updated_at)::bigint,
+                           EXTRACT(EPOCH FROM tree_modified_at)::bigint
                       FROM storage.folders
                      WHERE name = $1 AND user_id = $2 AND parent_id IS NULL
                     "#,
@@ -668,6 +711,7 @@ impl FolderRepository for FolderDbRepository {
                     Some(user_id),
                     existing.2,
                     existing.3,
+                    existing.4,
                 )
             }
         }
@@ -682,7 +726,8 @@ impl FolderRepository for FolderDbRepository {
         let sql = "SELECT fo.id::text, fo.name, fo.path, fo.parent_id::text, \
                           fo.user_id, \
                           EXTRACT(EPOCH FROM fo.created_at)::bigint, \
-                          EXTRACT(EPOCH FROM fo.updated_at)::bigint \
+                          EXTRACT(EPOCH FROM fo.updated_at)::bigint, \
+                          EXTRACT(EPOCH FROM fo.tree_modified_at)::bigint \
                      FROM storage.folders fo \
                     WHERE fo.is_trashed = false \
                       AND fo.lpath <@ (SELECT lpath FROM storage.folders WHERE id = $1::uuid) \
@@ -697,8 +742,8 @@ impl FolderRepository for FolderDbRepository {
             })?;
 
         rows.into_iter()
-            .map(|(id, name, path, pid, uid, ca, ma)| {
-                Self::row_to_folder(id, name, path, pid, uid, ca, ma)
+            .map(|(id, name, path, pid, uid, ca, ma, tma)| {
+                Self::row_to_folder(id, name, path, pid, uid, ca, ma, tma)
             })
             .collect()
     }
@@ -744,7 +789,8 @@ impl FolderRepository for FolderDbRepository {
                 "SELECT fo.id::text, fo.name, fo.path, fo.parent_id::text, \
                         fo.user_id, \
                         EXTRACT(EPOCH FROM fo.created_at)::bigint, \
-                        EXTRACT(EPOCH FROM fo.updated_at)::bigint \
+                        EXTRACT(EPOCH FROM fo.updated_at)::bigint, \
+                          EXTRACT(EPOCH FROM fo.tree_modified_at)::bigint \
                    FROM storage.folders fo \
                   WHERE fo.user_id = $1 \
                     AND fo.is_trashed = false \
@@ -768,8 +814,8 @@ impl FolderRepository for FolderDbRepository {
 
             return rows
                 .into_iter()
-                .map(|(id, name, path, pid, uid, ca, ma)| {
-                    Self::row_to_folder(id, name, path, pid, uid, ca, ma)
+                .map(|(id, name, path, pid, uid, ca, ma, tma)| {
+                    Self::row_to_folder(id, name, path, pid, uid, ca, ma, tma)
                 })
                 .collect();
         }
@@ -780,7 +826,8 @@ impl FolderRepository for FolderDbRepository {
                 "SELECT fo.id::text, fo.name, fo.path, fo.parent_id::text, \
                         fo.user_id, \
                         EXTRACT(EPOCH FROM fo.created_at)::bigint, \
-                        EXTRACT(EPOCH FROM fo.updated_at)::bigint \
+                        EXTRACT(EPOCH FROM fo.updated_at)::bigint, \
+                          EXTRACT(EPOCH FROM fo.tree_modified_at)::bigint \
                    FROM storage.folders fo \
                   WHERE fo.parent_id = $1::uuid \
                     AND fo.user_id = $2 \
@@ -798,7 +845,8 @@ impl FolderRepository for FolderDbRepository {
                 "SELECT fo.id::text, fo.name, fo.path, fo.parent_id::text, \
                         fo.user_id, \
                         EXTRACT(EPOCH FROM fo.created_at)::bigint, \
-                        EXTRACT(EPOCH FROM fo.updated_at)::bigint \
+                        EXTRACT(EPOCH FROM fo.updated_at)::bigint, \
+                          EXTRACT(EPOCH FROM fo.tree_modified_at)::bigint \
                    FROM storage.folders fo \
                   WHERE fo.parent_id IS NULL \
                     AND fo.user_id = $1 \
@@ -838,8 +886,8 @@ impl FolderRepository for FolderDbRepository {
         .map_err(|e| DomainError::internal_error("FolderDb", format!("search_folders: {e}")))?;
 
         rows.into_iter()
-            .map(|(id, name, path, pid, uid, ca, ma)| {
-                Self::row_to_folder(id, name, path, pid, uid, ca, ma)
+            .map(|(id, name, path, pid, uid, ca, ma, tma)| {
+                Self::row_to_folder(id, name, path, pid, uid, ca, ma, tma)
             })
             .collect()
     }
@@ -866,7 +914,8 @@ impl FolderRepository for FolderDbRepository {
             "SELECT fo.id::text, fo.name, fo.path, fo.parent_id::text, \
                     fo.user_id, \
                     EXTRACT(EPOCH FROM fo.created_at)::bigint, \
-                    EXTRACT(EPOCH FROM fo.updated_at)::bigint \
+                    EXTRACT(EPOCH FROM fo.updated_at)::bigint, \
+                          EXTRACT(EPOCH FROM fo.tree_modified_at)::bigint \
                FROM storage.folders fo \
               WHERE fo.user_id = $1 \
                 AND fo.is_trashed = false \
@@ -893,8 +942,8 @@ impl FolderRepository for FolderDbRepository {
         .map_err(|e| DomainError::internal_error("FolderDb", format!("descendant search: {e}")))?;
 
         rows.into_iter()
-            .map(|(id, name, path, pid, uid, ca, ma)| {
-                Self::row_to_folder(id, name, path, pid, uid, ca, ma)
+            .map(|(id, name, path, pid, uid, ca, ma, tma)| {
+                Self::row_to_folder(id, name, path, pid, uid, ca, ma, tma)
             })
             .collect()
     }
@@ -914,7 +963,8 @@ impl FolderRepository for FolderDbRepository {
                 r#"
                 SELECT id::text, name, path, parent_id::text, user_id,
                        EXTRACT(EPOCH FROM created_at)::bigint,
-                       EXTRACT(EPOCH FROM updated_at)::bigint
+                       EXTRACT(EPOCH FROM updated_at)::bigint,
+                       EXTRACT(EPOCH FROM tree_modified_at)::bigint
                   FROM storage.folders
                  WHERE parent_id = $1::uuid
                    AND NOT is_trashed
@@ -939,7 +989,8 @@ impl FolderRepository for FolderDbRepository {
                 r#"
                 SELECT id::text, name, path, parent_id::text, user_id,
                        EXTRACT(EPOCH FROM created_at)::bigint,
-                       EXTRACT(EPOCH FROM updated_at)::bigint
+                       EXTRACT(EPOCH FROM updated_at)::bigint,
+                       EXTRACT(EPOCH FROM tree_modified_at)::bigint
                   FROM storage.folders
                  WHERE parent_id IS NULL
                    AND NOT is_trashed
@@ -962,8 +1013,8 @@ impl FolderRepository for FolderDbRepository {
         .map_err(|e| DomainError::internal_error("FolderDb", format!("suggest: {e}")))?;
 
         rows.into_iter()
-            .map(|(id, name, path, pid, uid, ca, ma)| {
-                Self::row_to_folder(id, name, path, pid, Some(uid), ca, ma)
+            .map(|(id, name, path, pid, uid, ca, ma, tma)| {
+                Self::row_to_folder(id, name, path, pid, Some(uid), ca, ma, tma)
             })
             .collect()
     }
@@ -1100,6 +1151,7 @@ impl FolderDbRepository {
                 f.created_at,
                 f.updated_at              AS modified_at,
                 f.user_id,
+                NULL::text                AS blob_hash,
                 LOWER(f.name)             AS sort_str,
                 0::bigint                 AS type_order,
                 0::int                    AS folder_first
@@ -1118,6 +1170,7 @@ impl FolderDbRepository {
                 fm.created_at,
                 fm.updated_at             AS modified_at,
                 fm.user_id,
+                fm.blob_hash,
                 LOWER(fm.name)            AS sort_str,
                 fm.category_order::bigint AS type_order,
                 1::int                    AS folder_first
@@ -1241,7 +1294,7 @@ impl FolderDbRepository {
         let sql = format!(
             "WITH resources AS ({cte_inner}) \
              SELECT resource_type, id, name, folder_id, mime_type, size, \
-                    created_at, modified_at, user_id, sort_str, type_order, folder_first \
+                    created_at, modified_at, user_id, blob_hash, sort_str, type_order, folder_first \
              FROM resources \
              {where_clause} \
              {order_clause} \
@@ -1249,7 +1302,8 @@ impl FolderDbRepository {
         );
 
         // Row: (resource_type, id, name, folder_id, mime_type, size,
-        //        created_at, modified_at, user_id, sort_str, type_order, folder_first)
+        //        created_at, modified_at, user_id, blob_hash,
+        //        sort_str, type_order, folder_first)
         type Row = (
             String,
             Uuid,
@@ -1260,6 +1314,7 @@ impl FolderDbRepository {
             chrono::DateTime<chrono::Utc>,
             chrono::DateTime<chrono::Utc>,
             Uuid,
+            Option<String>,
             String,
             i64,
             i32,
@@ -1290,9 +1345,10 @@ impl FolderDbRepository {
                 created_at: r.6,
                 modified_at: r.7,
                 owner_id: r.8,
-                sort_str: r.9,
-                type_order: r.10,
-                folder_first: r.11,
+                blob_hash: r.9,
+                sort_str: r.10,
+                type_order: r.11,
+                folder_first: r.12,
             })
             .collect())
     }
diff --git a/src/infrastructure/repositories/pg/recent_items_pg_repository.rs b/src/infrastructure/repositories/pg/recent_items_pg_repository.rs
index 1a3cc33c..93e44c05 100644
--- a/src/infrastructure/repositories/pg/recent_items_pg_repository.rs
+++ b/src/infrastructure/repositories/pg/recent_items_pg_repository.rs
@@ -217,6 +217,7 @@ impl RecentItemsRepositoryPort for RecentItemsPgRepository {
         fld.created_at                   AS resource_created_at,
         fld.updated_at                   AS modified_at,
         fld.user_id                      AS owner_id,
+        NULL::text                       AS blob_hash,
         (fld.user_id = $1::uuid)         AS is_owner,
         ur.accessed_at                   AS accessed_at,
         fld.path::text                   AS resource_path,
@@ -239,6 +240,7 @@ impl RecentItemsRepositoryPort for RecentItemsPgRepository {
         f.created_at                     AS resource_created_at,
         f.updated_at                     AS modified_at,
         f.user_id                        AS owner_id,
+        f.blob_hash,
         (f.user_id = $1::uuid)           AS is_owner,
         ur.accessed_at                   AS accessed_at,
         COALESCE(pfld.path::text || '/' || f.name, f.name) AS resource_path,
@@ -483,6 +485,7 @@ LIMIT $6"
                     resource_created_at: row.get("resource_created_at"),
                     modified_at: row.get("modified_at"),
                     owner_id: row.get("owner_id"),
+                    blob_hash: row.try_get("blob_hash").ok(),
                     is_owner: row.try_get("is_owner").unwrap_or(false),
                     accessed_at: row.get("accessed_at"),
                     path: row.try_get("resource_path").ok(),
diff --git a/src/infrastructure/repositories/pg/trash_db_repository.rs b/src/infrastructure/repositories/pg/trash_db_repository.rs
index 191ccecb..ab9d3741 100644
--- a/src/infrastructure/repositories/pg/trash_db_repository.rs
+++ b/src/infrastructure/repositories/pg/trash_db_repository.rs
@@ -261,6 +261,7 @@ impl TrashDbRepository {
         fld.created_at                                       AS resource_created_at,
         fld.updated_at                                       AS modified_at,
         fld.user_id                                          AS owner_id,
+        NULL::text                                           AS blob_hash,
         fld.trashed_at                                       AS trashed_at,
         (fld.trashed_at + ($7::int * INTERVAL '1 day'))      AS deletion_date,
         fld.path::text                                       AS resource_path,
@@ -286,6 +287,7 @@ impl TrashDbRepository {
         f.created_at                                         AS resource_created_at,
         f.updated_at                                         AS modified_at,
         f.user_id                                            AS owner_id,
+        f.blob_hash,
         f.trashed_at                                         AS trashed_at,
         (f.trashed_at + ($7::int * INTERVAL '1 day'))        AS deletion_date,
         COALESCE(pfld.path::text || '/' || f.name, f.name)   AS resource_path,
@@ -473,6 +475,7 @@ LIMIT $6"
                     resource_created_at: row.get("resource_created_at"),
                     modified_at: row.get("modified_at"),
                     owner_id: row.get("owner_id"),
+                    blob_hash: row.try_get("blob_hash").ok(),
                     trashed_at,
                     deletion_date,
                     path: row.try_get("resource_path").ok(),
diff --git a/src/infrastructure/services/path_resolver_service.rs b/src/infrastructure/services/path_resolver_service.rs
index 291db682..ea187db5 100644
--- a/src/infrastructure/services/path_resolver_service.rs
+++ b/src/infrastructure/services/path_resolver_service.rs
@@ -145,6 +145,7 @@ impl PathResolverService {
 
         match resource_type.as_str() {
             "folder" => Ok(ResolvedResource::Folder(FolderDto {
+                etag: id.clone(),
                 id,
                 name: name.clone(),
                 path: res_path,
@@ -160,6 +161,11 @@ impl PathResolverService {
             _ => {
                 let mime = mime_type.unwrap_or_else(|| "application/octet-stream".to_string());
                 let sz = size.unwrap_or(0) as u64;
+                // `content_hash`/`etag` are empty here: this resolver
+                // path doesn't select `blob_hash` from SQL — callers
+                // are doing existence/type discrimination, not ETag
+                // emission. If a caller ever needs an ETag from this
+                // codepath, widen the SELECT and populate properly.
                 Ok(ResolvedResource::File(FileDto {
                     id,
                     name: name.clone(),
@@ -175,6 +181,7 @@ impl PathResolverService {
                     size_formatted: format_file_size(sz),
                     owner_id: uid,
                     sort_date: None,
+                    content_hash: String::new(),
                     etag: String::new(),
                 }))
             }
diff --git a/src/interfaces/api/handlers/favorites_handler.rs b/src/interfaces/api/handlers/favorites_handler.rs
index 05d21264..c32a5a20 100644
--- a/src/interfaces/api/handlers/favorites_handler.rs
+++ b/src/interfaces/api/handlers/favorites_handler.rs
@@ -20,6 +20,7 @@ use crate::application::dtos::folder_dto::FolderDto;
 use crate::application::dtos::grant_dto::{ResourceContentDto, ResourceTypeDto};
 use crate::application::ports::favorites_ports::FavoritesUseCase;
 use crate::application::services::favorites_service::FavoritesService;
+use crate::domain::entities::file::File;
 use crate::interfaces::errors::AppError;
 use crate::interfaces::middleware::auth::AuthUser;
 
@@ -253,8 +254,10 @@ pub async fn list_favorites_resources(
                     };
 
                     if row.resource_type == "folder" {
+                        let resource_id = row.resource_id.to_string();
                         let dto = FolderDto {
-                            id: row.resource_id.to_string(),
+                            etag: resource_id.clone(),
+                            id: resource_id,
                             name: row.name.clone(),
                             path,
                             parent_id: row.parent_id.map(|u| u.to_string()),
@@ -277,6 +280,18 @@ pub async fn list_favorites_resources(
                             .as_deref()
                             .unwrap_or("application/octet-stream");
                         let size_bytes = row.size.max(0) as u64;
+                        // Route ETag through `File::compute_etag` so
+                        // this listing's `etag` byte-equals what
+                        // GET/HEAD/PROPFIND would return for the same
+                        // file. `blob_hash` is `None` only for
+                        // folder rows, which take the other branch.
+                        let modified_at_u = row.modified_at.timestamp() as u64;
+                        let content_hash = row.blob_hash.clone().unwrap_or_default();
+                        let etag = if content_hash.is_empty() {
+                            String::new()
+                        } else {
+                            File::compute_etag(&content_hash, modified_at_u)
+                        };
                         let dto = FileDto {
                             id: row.resource_id.to_string(),
                             name: row.name.clone(),
@@ -285,7 +300,7 @@ pub async fn list_favorites_resources(
                             mime_type: std::sync::Arc::from(mime),
                             folder_id: row.parent_id.map(|u| u.to_string()),
                             created_at: row.resource_created_at.timestamp() as u64,
-                            modified_at: row.modified_at.timestamp() as u64,
+                            modified_at: modified_at_u,
                             icon_class: std::sync::Arc::from(icon_class_for(&row.name, mime)),
                             icon_special_class: std::sync::Arc::from(icon_special_class_for(
                                 &row.name, mime,
@@ -294,7 +309,8 @@ pub async fn list_favorites_resources(
                             size_formatted: format_file_size(size_bytes),
                             owner_id: Some(row.owner_id.to_string()),
                             sort_date: None,
-                            etag: String::new(),
+                            content_hash,
+                            etag,
                         };
                         FavoritesResourceItemDto {
                             resource_type: ResourceTypeDto::File,
diff --git a/src/interfaces/api/handlers/file_handler.rs b/src/interfaces/api/handlers/file_handler.rs
index 0a7866a9..aface7df 100644
--- a/src/interfaces/api/handlers/file_handler.rs
+++ b/src/interfaces/api/handlers/file_handler.rs
@@ -593,7 +593,11 @@ impl FileHandler {
                 .into_response();
         }
 
-        let etag = format!("\"{}-{}\"", id, file_dto.modified_at);
+        // Route through `FileDto::etag` so this REST download
+        // endpoint, WebDAV/NextCloud GET, HEAD, PROPFIND, and PUT all
+        // emit the same opaque token for the same file — see
+        // `File::etag` for the formula.
+        let etag = format!("\"{}\"", file_dto.etag);
 
         // ── ETag (304 Not Modified) ──────────────────────────────────
         if let Some(inm) = headers.get(header::IF_NONE_MATCH)
diff --git a/src/interfaces/api/handlers/folder_handler.rs b/src/interfaces/api/handlers/folder_handler.rs
index 69775bdb..da113be5 100644
--- a/src/interfaces/api/handlers/folder_handler.rs
+++ b/src/interfaces/api/handlers/folder_handler.rs
@@ -26,6 +26,7 @@ use crate::application::ports::folder_ports::FolderUseCase;
 use crate::application::ports::trash_ports::TrashUseCase;
 use crate::application::services::folder_service::FolderService;
 use crate::common::di::AppState as GlobalAppState;
+use crate::domain::entities::file::File;
 use crate::interfaces::errors::AppError;
 use crate::interfaces::middleware::auth::AuthUser;
 
@@ -692,8 +693,10 @@ pub async fn list_folder_resources(
                 .into_iter()
                 .map(|row| {
                     if row.resource_type == "folder" {
+                        let resource_id = row.id.to_string();
                         let dto = FolderDto {
-                            id: row.id.to_string(),
+                            etag: resource_id.clone(),
+                            id: resource_id,
                             name: row.name.clone(),
                             path: String::new(), // cleared — share recipients must not see hierarchy
                             parent_id: row.parent_id.map(|u| u.to_string()),
@@ -715,6 +718,20 @@ pub async fn list_folder_resources(
                             .as_deref()
                             .unwrap_or("application/octet-stream");
                         let size_bytes = row.size.max(0) as u64;
+                        // `blob_hash` is `Some(_)` for file rows in the
+                        // UNION ALL (`NULL` for folders). Route the
+                        // ETag formula through `File::compute_etag` —
+                        // the single source of truth shared with
+                        // GET/HEAD/PROPFIND/PUT response — so this
+                        // listing's `etag` byte-equals what a
+                        // conditional request would compare against.
+                        let modified_at_u = row.modified_at.timestamp() as u64;
+                        let content_hash = row.blob_hash.clone().unwrap_or_default();
+                        let etag = if content_hash.is_empty() {
+                            String::new()
+                        } else {
+                            File::compute_etag(&content_hash, modified_at_u)
+                        };
                         let dto = FileDto {
                             id: row.id.to_string(),
                             name: row.name.clone(),
@@ -730,7 +747,8 @@ pub async fn list_folder_resources(
                             size_formatted: format_file_size(size_bytes),
                             owner_id: Some(row.owner_id.to_string()),
                             sort_date: None,
-                            etag: String::new(),
+                            content_hash,
+                            etag,
                         };
                         FolderResourceItemDto {
                             resource_type: ResourceTypeDto::File,
diff --git a/src/interfaces/api/handlers/recent_handler.rs b/src/interfaces/api/handlers/recent_handler.rs
index fe6d978a..14dcb189 100644
--- a/src/interfaces/api/handlers/recent_handler.rs
+++ b/src/interfaces/api/handlers/recent_handler.rs
@@ -19,6 +19,7 @@ use crate::application::dtos::recent_dto::{
 };
 use crate::application::ports::recent_ports::RecentItemsUseCase;
 use crate::application::services::recent_service::RecentService;
+use crate::domain::entities::file::File;
 use crate::interfaces::errors::AppError;
 use crate::interfaces::middleware::auth::AuthUser;
 use uuid::Uuid;
@@ -283,8 +284,10 @@ pub async fn list_recent_resources(
                     };
 
                     if row.resource_type == "folder" {
+                        let resource_id = row.resource_id.to_string();
                         let dto = FolderDto {
-                            id: row.resource_id.to_string(),
+                            etag: resource_id.clone(),
+                            id: resource_id,
                             name: row.name.clone(),
                             path,
                             parent_id: row.parent_id.map(|u| u.to_string()),
@@ -307,6 +310,16 @@ pub async fn list_recent_resources(
                             .as_deref()
                             .unwrap_or("application/octet-stream");
                         let size_bytes = row.size.max(0) as u64;
+                        // Route ETag through `File::compute_etag` so this
+                        // listing matches GET/HEAD/PROPFIND byte-for-byte
+                        // for the same file.
+                        let modified_at_u = row.modified_at.timestamp() as u64;
+                        let content_hash = row.blob_hash.clone().unwrap_or_default();
+                        let etag = if content_hash.is_empty() {
+                            String::new()
+                        } else {
+                            File::compute_etag(&content_hash, modified_at_u)
+                        };
                         let dto = FileDto {
                             id: row.resource_id.to_string(),
                             name: row.name.clone(),
@@ -315,7 +328,7 @@ pub async fn list_recent_resources(
                             mime_type: std::sync::Arc::from(mime),
                             folder_id: row.parent_id.map(|u| u.to_string()),
                             created_at: row.resource_created_at.timestamp() as u64,
-                            modified_at: row.modified_at.timestamp() as u64,
+                            modified_at: modified_at_u,
                             icon_class: std::sync::Arc::from(icon_class_for(&row.name, mime)),
                             icon_special_class: std::sync::Arc::from(icon_special_class_for(
                                 &row.name, mime,
@@ -324,7 +337,8 @@ pub async fn list_recent_resources(
                             size_formatted: format_file_size(size_bytes),
                             owner_id: Some(row.owner_id.to_string()),
                             sort_date: None,
-                            etag: String::new(),
+                            content_hash,
+                            etag,
                         };
                         RecentResourceItemDto {
                             resource_type: ResourceTypeDto::File,
diff --git a/src/interfaces/api/handlers/webdav_handler.rs b/src/interfaces/api/handlers/webdav_handler.rs
index a0f57afe..ef339dff 100644
--- a/src/interfaces/api/handlers/webdav_handler.rs
+++ b/src/interfaces/api/handlers/webdav_handler.rs
@@ -69,6 +69,37 @@ pub(crate) fn encode_uri_path(path: &str) -> String {
         .join("/")
 }
 
+/// Build the `<D:href>` value for a non-collection (file) resource.
+///
+/// RFC 4918 §5.2 distinguishes collection (folder) URLs from
+/// non-collection URLs by a trailing `/`. Files use NO trailing
+/// slash. Mirror of [`webdav_collection_href`] — keep both arms
+/// of the choice on the same screen so an "is it a file or a
+/// folder?" reviewer can verify both branches at once.
+fn webdav_href(path: &str) -> String {
+    format!("/webdav/{}", encode_uri_path(path))
+}
+
+/// Build the `<D:href>` value for a collection (folder) resource.
+///
+/// Always terminates with `/` — RFC 4918 §5.2 requires collection
+/// URLs to end in a slash, and strict WebDAV clients (notably the
+/// NextCloud desktop sync engine, which also speaks to this
+/// endpoint) abort multi-status parses with
+/// `Invalid href "<…>" expected starting with "<requested-url>"`
+/// when the response's own-entry href is missing the trailing `/`.
+/// PROPPATCH and LOCK responses on folders MUST use this — using
+/// [`webdav_href`] for a folder is the bug class this helper
+/// exists to prevent.
+fn webdav_collection_href(path: &str) -> String {
+    let h = webdav_href(path);
+    if h.ends_with('/') {
+        h
+    } else {
+        format!("{}/", h)
+    }
+}
+
 // Create a custom DAV header since it's not in the standard headers
 const HEADER_DAV: HeaderName = HeaderName::from_static("dav");
 const HEADER_LOCK_TOKEN: HeaderName = HeaderName::from_static("lock-token");
@@ -353,6 +384,7 @@ async fn handle_propfind(
         // Root folder
         let root_folder = FolderDto {
             id: "root".to_string(),
+            etag: "root".to_string(),
             name: "".to_string(),
             path: "".to_string(),
             parent_id: None,
@@ -604,12 +636,35 @@ async fn build_streaming_propfind_response(
  * @return XML response with property modification results
  */
 async fn handle_proppatch(
-    _state: Arc<AppState>,
+    state: Arc<AppState>,
     req: Request<Body>,
     path: String,
 ) -> Result<Response<Body>, AppError> {
     let _user = extract_user(&req)?;
 
+    // Resolve the target resource type BEFORE consuming the body so
+    // we can pick the correct href shape in the multi-status
+    // response. RFC 4918 §5.2 + strict WebDAV-client parser rules
+    // require a trailing `/` for collection hrefs; emitting
+    // `/webdav/foo` for a folder breaks NC-desktop / Cyberduck /
+    // other multi-status consumers the same way the NC PROPFIND
+    // bug did. An empty / `/` path is the root, always a
+    // collection. A path that resolves to neither file nor folder
+    // (e.g. PROPPATCH on a resource that doesn't exist) defaults
+    // to non-collection — matches the request-line shape the
+    // client used, since collection paths conventionally arrive
+    // with trailing `/` already trimmed by routing.
+    let is_collection = if path.is_empty() || path == "/" {
+        true
+    } else {
+        state
+            .applications
+            .folder_service
+            .get_folder_by_path(&path)
+            .await
+            .is_ok()
+    };
+
     // Read request body (XML — bounded to 1 MB)
     let body_bytes = body::to_bytes(req.into_body(), MAX_XML_BODY)
         .await
@@ -635,8 +690,12 @@ async fn handle_proppatch(
         results.push((prop, true));
     }
 
-    // Generate response
-    let href = format!("/webdav/{}", encode_uri_path(&path));
+    // Generate response — collection vs file href chosen above.
+    let href = if is_collection {
+        webdav_collection_href(&path)
+    } else {
+        webdav_href(&path)
+    };
     let mut response_body = Vec::new();
     WebDavAdapter::generate_proppatch_response(&mut response_body, &href, &results).map_err(
         |e| AppError::internal_error(format!("Failed to generate PROPPATCH response: {}", e)),
@@ -706,7 +765,7 @@ async fn handle_get(
         .status(StatusCode::OK)
         .header(header::CONTENT_TYPE, &*file.mime_type)
         .header(header::CONTENT_LENGTH, file.size)
-        .header(header::ETAG, format!("\"{}\"", file.id))
+        .header(header::ETAG, format!("\"{}\"", file.etag))
         .header(
             header::LAST_MODIFIED,
             chrono::DateTime::<Utc>::from_timestamp(file.created_at as i64, 0)
@@ -747,7 +806,7 @@ async fn handle_head(
                     .status(StatusCode::OK)
                     .header(header::CONTENT_TYPE, "httpd/unix-directory")
                     .header(header::CONTENT_LENGTH, 0)
-                    .header(header::ETAG, format!("\"{}\"", folder.id))
+                    .header(header::ETAG, format!("\"{}\"", folder.etag))
                     .body(Body::empty())
                     .unwrap());
             }
@@ -756,7 +815,7 @@ async fn handle_head(
                     .status(StatusCode::OK)
                     .header(header::CONTENT_TYPE, &*file.mime_type)
                     .header(header::CONTENT_LENGTH, file.size)
-                    .header(header::ETAG, format!("\"{}\"", file.id))
+                    .header(header::ETAG, format!("\"{}\"", file.etag))
                     .header(
                         header::LAST_MODIFIED,
                         chrono::DateTime::<Utc>::from_timestamp(file.created_at as i64, 0)
@@ -777,7 +836,7 @@ async fn handle_head(
             .status(StatusCode::OK)
             .header(header::CONTENT_TYPE, "httpd/unix-directory")
             .header(header::CONTENT_LENGTH, 0)
-            .header(header::ETAG, format!("\"{}\"", folder.id))
+            .header(header::ETAG, format!("\"{}\"", folder.etag))
             .body(Body::empty())
             .unwrap());
     }
@@ -793,7 +852,7 @@ async fn handle_head(
         .status(StatusCode::OK)
         .header(header::CONTENT_TYPE, &*file.mime_type)
         .header(header::CONTENT_LENGTH, file.size)
-        .header(header::ETAG, format!("\"{}\"", file.id))
+        .header(header::ETAG, format!("\"{}\"", file.etag))
         .header(
             header::LAST_MODIFIED,
             chrono::DateTime::<Utc>::from_timestamp(file.created_at as i64, 0)
@@ -1686,6 +1745,24 @@ async fn handle_lock(
 ) -> Result<Response<Body>, AppError> {
     let user = extract_user(&req)?;
 
+    // Determine collection-vs-file for href shape. Root + known
+    // folders → collection; everything else (existing files,
+    // lock-null on a non-existent path) → file. RFC 4918 §9.10.1
+    // allows LOCK on a non-existent resource (the "lock-null
+    // resource" pattern used by Office save flows) — that arm
+    // falls through to the file href shape, matching the
+    // request-line shape clients send.
+    let is_collection = if path.is_empty() || path == "/" {
+        true
+    } else {
+        state
+            .applications
+            .folder_service
+            .get_folder_by_path(&path)
+            .await
+            .is_ok()
+    };
+
     // Get the headers that we need
     let depth = req
         .headers()
@@ -1735,8 +1812,12 @@ async fn handle_lock(
                 AppError::precondition_failed(format!("Lock token not found or expired: {}", token))
             })?;
 
-        // Generate response
-        let href = format!("/webdav/{}", encode_uri_path(&path));
+        // Generate response — collection vs file href chosen above.
+        let href = if is_collection {
+            webdav_collection_href(&path)
+        } else {
+            webdav_href(&path)
+        };
         let mut response_body = Vec::new();
         WebDavAdapter::generate_lock_response(&mut response_body, &entry.info, &href).map_err(
             |e| AppError::internal_error(format!("Failed to generate LOCK response: {}", e)),
@@ -1771,8 +1852,12 @@ async fn handle_lock(
             ))
         })?;
 
-        // Generate response
-        let href = format!("/webdav/{}", encode_uri_path(&path));
+        // Generate response — collection vs file href chosen above.
+        let href = if is_collection {
+            webdav_collection_href(&path)
+        } else {
+            webdav_href(&path)
+        };
         let mut response_body = Vec::new();
         WebDavAdapter::generate_lock_response(&mut response_body, &entry.info, &href).map_err(
             |e| AppError::internal_error(format!("Failed to generate LOCK response: {}", e)),
@@ -1836,3 +1921,49 @@ async fn handle_unlock(
         .body(Body::empty())
         .unwrap())
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_webdav_href_no_trailing_slash() {
+        assert_eq!(
+            webdav_href("Documents/report.pdf"),
+            "/webdav/Documents/report.pdf"
+        );
+        assert_eq!(webdav_href("file.txt"), "/webdav/file.txt");
+    }
+
+    #[test]
+    fn test_webdav_collection_href_appends_slash_when_missing() {
+        assert_eq!(webdav_collection_href("Documents"), "/webdav/Documents/");
+        assert_eq!(
+            webdav_collection_href("Documents/subfolder"),
+            "/webdav/Documents/subfolder/"
+        );
+    }
+
+    #[test]
+    fn test_webdav_collection_href_idempotent_when_already_slashed() {
+        // `encode_uri_path` never emits a trailing `/` of its own
+        // because the path argument is already trimmed by routing,
+        // but the helper still has to be robust to a path that
+        // happens to end in `/` — exercise the idempotence path.
+        assert_eq!(webdav_collection_href("Documents/"), "/webdav/Documents/");
+    }
+
+    #[test]
+    fn test_webdav_href_preserves_url_encoding() {
+        // Spaces and Unicode must percent-encode at the segment level,
+        // not get a verbatim `%20` re-encoded as `%2520`.
+        assert_eq!(
+            webdav_href("My Photos/vacation pic.jpg"),
+            "/webdav/My%20Photos/vacation%20pic.jpg"
+        );
+        assert_eq!(
+            webdav_collection_href("My Photos/2024"),
+            "/webdav/My%20Photos/2024/"
+        );
+    }
+}
diff --git a/src/interfaces/nextcloud/basic_auth_middleware.rs b/src/interfaces/nextcloud/basic_auth_middleware.rs
index 4ebeb140..52d65529 100644
--- a/src/interfaces/nextcloud/basic_auth_middleware.rs
+++ b/src/interfaces/nextcloud/basic_auth_middleware.rs
@@ -114,6 +114,15 @@ pub async fn basic_auth_middleware(
                 );
                 return Err(NextcloudAuthError::Unauthorized);
             }
+            // Populate the deferred `user_id` field on the request
+            // tracing span (declared in `middleware/trace_span.rs::ClientIpMakeSpan`).
+            // Mirrors what `interfaces/middleware/auth.rs` does for the
+            // JWT path so the two auth surfaces produce log lines with
+            // the same structured shape — without this, every NC
+            // request would appear in the logs with `user_id=-`,
+            // making it harder to correlate WebDAV / OCS activity to
+            // a specific principal.
+            tracing::Span::current().record("user_id", user_id.to_string());
             request.extensions_mut().insert(Arc::new(CurrentUser {
                 id: user_id,
                 username: uname,
diff --git a/src/interfaces/nextcloud/report_handler.rs b/src/interfaces/nextcloud/report_handler.rs
index 03311557..c59a07f2 100644
--- a/src/interfaces/nextcloud/report_handler.rs
+++ b/src/interfaces/nextcloud/report_handler.rs
@@ -21,6 +21,7 @@ use crate::application::ports::file_ports::FileRetrievalUseCase;
 use crate::application::ports::folder_ports::FolderUseCase;
 use crate::application::ports::inbound::SearchUseCase;
 use crate::common::di::AppState;
+use crate::domain::entities::file::File;
 use crate::interfaces::errors::AppError;
 use crate::interfaces::middleware::auth::CurrentUser;
 use crate::interfaces::nextcloud::webdav_handler::{
@@ -250,6 +251,16 @@ async fn handle_search(
 
 /// Build a `FileDto` from a search file result.
 fn file_dto_from_search(fr: &crate::application::dtos::search_dto::SearchFileResultDto) -> FileDto {
+    // Route ETag through `File::compute_etag` so REPORT/SEARCH hits
+    // emit the same opaque token NC's sync client cached from the
+    // earlier PROPFIND walk — without this, NC's conditional-request
+    // logic on search results disagrees with its own cached state
+    // and triggers a spurious re-fetch.
+    let etag = if fr.blob_hash.is_empty() {
+        String::new()
+    } else {
+        File::compute_etag(&fr.blob_hash, fr.modified_at)
+    };
     FileDto {
         id: fr.id.clone(),
         name: fr.name.clone(),
@@ -267,7 +278,8 @@ fn file_dto_from_search(fr: &crate::application::dtos::search_dto::SearchFileRes
         size_formatted: format_file_size(fr.size),
         owner_id: None,
         sort_date: None,
-        etag: String::new(),
+        content_hash: fr.blob_hash.clone(),
+        etag,
     }
 }
 
@@ -276,6 +288,7 @@ fn folder_dto_from_search(
     sr: &crate::application::dtos::search_dto::SearchFolderResultDto,
 ) -> FolderDto {
     FolderDto {
+        etag: sr.id.clone(),
         id: sr.id.clone(),
         name: sr.name.clone(),
         path: sr.path.clone(),
diff --git a/src/interfaces/nextcloud/webdav_handler.rs b/src/interfaces/nextcloud/webdav_handler.rs
index af813e8b..8be9577b 100644
--- a/src/interfaces/nextcloud/webdav_handler.rs
+++ b/src/interfaces/nextcloud/webdav_handler.rs
@@ -62,10 +62,32 @@ pub fn nc_to_internal_path(username: &str, subpath: &str) -> Result<String, AppE
     Ok(format!("{}/{}", home, subpath))
 }
 
+/// Build the Nextcloud DAV href for a **collection** (folder). Always
+/// terminates with `/` — RFC 4918 §5.2 requires collection URLs to end
+/// in a slash, and the Nextcloud desktop client strictly enforces this
+/// for the "own entry" href in PROPFIND multi-status responses: a
+/// PROPFIND on `/remote.php/dav/files/admin/ext/` whose first response
+/// `<d:href>` doesn't end in `/` aborts the parse with
+/// `Invalid href "<…>" expected starting with "<requested-url>"` and
+/// surfaces as `Network request error "Erreur inconnue" HTTP status
+/// 207` in the client log. Files use [`nc_href`] (no trailing slash).
+pub fn nc_collection_href(username: &str, subpath: &str) -> String {
+    let h = nc_href(username, subpath);
+    if h.ends_with('/') {
+        h
+    } else {
+        format!("{}/", h)
+    }
+}
+
 /// Build the Nextcloud DAV href for a resource.
 ///
 /// Each path segment is URL-encoded individually so filenames with spaces,
 /// `#`, `%`, or non-ASCII characters produce valid PROPFIND hrefs.
+///
+/// Returns NO trailing slash for non-empty subpaths. Callers rendering
+/// a **collection** must use [`nc_collection_href`] (or append `/`
+/// manually) to satisfy RFC 4918 §5.2 and the NC client's parser.
 pub fn nc_href(username: &str, subpath: &str) -> String {
     let subpath = subpath.trim_matches('/');
     let encoded_user = urlencoding::encode(username);
@@ -120,9 +142,18 @@ pub async fn handle_nc_webdav(
 // ──────────────────── OPTIONS ────────────────────
 
 fn handle_options() -> Result<Response<Body>, AppError> {
+    // Advertise WebDAV compliance classes 1 + 3 only.
+    // Class 2 (LOCK/UNLOCK) is intentionally omitted because the NC
+    // surface has no LOCK/UNLOCK dispatch arm — claiming class 2
+    // would invite clients (notably the NC desktop sync engine) to
+    // start sending LOCK requests we then 405. Class 3 covers the
+    // weak-resource-validators behaviour PROPFIND already implements.
+    // If LOCK is ever wired in here, restore "1, 2, 3" in the same
+    // commit as the LOCK arm — never split the advertisement from
+    // the implementation.
     Ok(Response::builder()
         .status(StatusCode::OK)
-        .header(HEADER_DAV, "1, 2, 3")
+        .header(HEADER_DAV, "1, 3")
         .header(
             header::ALLOW,
             "OPTIONS, GET, HEAD, PUT, DELETE, MKCOL, MOVE, PROPFIND, PROPPATCH, REPORT, SEARCH",
@@ -318,11 +349,18 @@ async fn handle_get(
         chrono::DateTime::<Utc>::from_timestamp(timestamp_to_i64(file.modified_at), 0)
             .unwrap_or_else(Utc::now);
 
+    // ETag comes from `FileDto::etag` (populated from `File::etag()`
+    // in the `From<File>` impl) — single source of truth, so GET,
+    // HEAD, PUT-response, MOVE, and PROPFIND all emit byte-identical
+    // values for the same file. NC's sync engine compares cached
+    // PROPFIND ETags against GET/HEAD responses; using `file.id` here
+    // (a UUID) while PROPFIND emitted the blob hash made NC see
+    // every file as "remotely changed" on first descent.
     Ok(Response::builder()
         .status(StatusCode::OK)
         .header(header::CONTENT_TYPE, file.mime_type.as_ref())
         .header(header::CONTENT_LENGTH, file.size)
-        .header(header::ETAG, format!("\"{}\"", file.id))
+        .header(header::ETAG, format!("\"{}\"", file.etag))
         .header(header::LAST_MODIFIED, modified_at.to_rfc2822())
         .body(Body::from_stream(std::pin::Pin::from(stream)))
         .unwrap())
@@ -370,11 +408,14 @@ async fn handle_head(
         chrono::DateTime::<Utc>::from_timestamp(timestamp_to_i64(file.modified_at), 0)
             .unwrap_or_else(Utc::now);
 
+    // ETag comes from `FileDto::etag` — see the same comment block on
+    // the GET handler. HEAD and GET must agree byte-for-byte; pulling
+    // both from the same DTO field guarantees that.
     Ok(Response::builder()
         .status(StatusCode::OK)
         .header(header::CONTENT_TYPE, file.mime_type.as_ref())
         .header(header::CONTENT_LENGTH, file.size)
-        .header(header::ETAG, format!("\"{}\"", file.id))
+        .header(header::ETAG, format!("\"{}\"", file.etag))
         .header(header::LAST_MODIFIED, modified_at.to_rfc2822())
         .body(Body::empty())
         .unwrap())
@@ -394,23 +435,40 @@ async fn handle_proppatch(
 
     let body_str = String::from_utf8_lossy(&body_bytes);
 
+    // Resolve the target resource once — needed for two things:
+    //  1. Applying the oc:favorite mutation when the PROPPATCH body
+    //     carries one (`item_type` distinguishes file vs folder rows
+    //     in the favorites table).
+    //  2. Picking the right `<d:href>` shape in the multi-status
+    //     response: collection (folder) hrefs MUST end in `/` per
+    //     RFC 4918 §5.2 — see `nc_collection_href` for the full
+    //     reasoning. Without this distinction the NC desktop client
+    //     parser aborted on PROPFIND; PROPPATCH would hit the same
+    //     wall the moment the user favourited a folder.
+    //
+    // When the resource is missing we tolerate it for the no-op
+    // PROPPATCH path (no favorite directive in the body) — matches
+    // the prior behaviour. A PROPPATCH that *does* try to set
+    // favorite on a missing resource still returns NotFound.
+    let internal_path = nc_to_internal_path(&user.username, subpath)?;
+    let file_service = &state.applications.file_retrieval_service;
+    let folder_service = &state.applications.folder_service;
+    let resource = if let Ok(file) = file_service.get_file_by_path(&internal_path).await {
+        Some((file.id, "file"))
+    } else if let Ok(folder) = folder_service.get_folder_by_path(&internal_path).await {
+        Some((folder.id, "folder"))
+    } else {
+        None
+    };
+    let is_collection = matches!(resource, Some((_, "folder")));
+
     // Parse oc:favorite value from PROPPATCH XML.
     let favorite_value = parse_proppatch_favorite(&body_str);
 
     if let Some(value) = favorite_value {
-        let internal_path = nc_to_internal_path(&user.username, subpath)?;
-        let file_service = &state.applications.file_retrieval_service;
-        let folder_service = &state.applications.folder_service;
-
-        // Determine item_id and item_type.
-        let (item_id, item_type) =
-            if let Ok(file) = file_service.get_file_by_path(&internal_path).await {
-                (file.id, "file")
-            } else if let Ok(folder) = folder_service.get_folder_by_path(&internal_path).await {
-                (folder.id, "folder")
-            } else {
-                return Err(AppError::not_found("Resource not found"));
-            };
+        let Some((item_id, item_type)) = resource else {
+            return Err(AppError::not_found("Resource not found"));
+        };
 
         if let Some(fav_svc) = state.favorites_service.as_ref() {
             if value == 1 {
@@ -431,8 +489,15 @@ async fn handle_proppatch(
         }
     }
 
-    // Return 207 Multi-Status with success response using quick_xml for safe escaping.
-    let href = nc_href(&user.username, subpath);
+    // Return 207 Multi-Status with success response using quick_xml
+    // for safe escaping. Collection vs file href chosen by resource
+    // type to satisfy the RFC 4918 §5.2 trailing-slash invariant —
+    // see the comment block at the top of this function.
+    let href = if is_collection {
+        nc_collection_href(&user.username, subpath)
+    } else {
+        nc_href(&user.username, subpath)
+    };
     let mut buf = Vec::new();
     {
         let mut xml = Writer::new(&mut buf);
@@ -804,9 +869,13 @@ async fn handle_move(
         let dest_internal = nc_to_internal_path(&user.username, &dest_subpath)?;
         let mut builder = Response::builder().status(StatusCode::CREATED);
         if let Ok(moved) = file_service.get_file_by_path(&dest_internal).await {
+            // Route through `FileDto::etag` so the MOVE response
+            // matches what a subsequent PROPFIND on the destination
+            // will return — `moved.id` (UUID) would differ from the
+            // blob hash and trigger NC's "remote changed" detection.
             builder = builder
-                .header(header::ETAG, format!("\"{}\"", moved.id))
-                .header("oc-etag", format!("\"{}\"", moved.id));
+                .header(header::ETAG, format!("\"{}\"", moved.etag))
+                .header("oc-etag", format!("\"{}\"", moved.etag));
         }
 
         return Ok(builder.body(Body::empty()).unwrap());
@@ -935,9 +1004,10 @@ async fn write_nc_multistatus<W: std::io::Write>(
     ms.push_attribute(("xmlns:ocs", "http://open-collaboration-services.org/ns"));
     xml.write_event(Event::Start(ms)).xml_err()?;
 
-    // Current folder entry.
+    // Current folder entry. Collection hrefs MUST end in `/` (RFC 4918
+    // §5.2 + strict NC-client enforcement — see `nc_collection_href`).
     if let Some(f) = folder {
-        let href = nc_href(username, subpath);
+        let href = nc_collection_href(username, subpath);
         let file_id = resolve_folder_id(file_id_svc, &f.id).await;
         let oc_id = file_id.map(|id| format_oc_id(id, file_id_svc));
         write_folder_response(
@@ -981,14 +1051,14 @@ async fn write_nc_multistatus<W: std::io::Write>(
             )?;
         }
 
-        // Subfolders.
+        // Subfolders — also collections, same trailing-slash rule.
         for sf in subfolders {
             let child_sub = if subpath.is_empty() {
                 sf.name.clone()
             } else {
                 format!("{}/{}", subpath.trim_end_matches('/'), sf.name)
             };
-            let href = format!("{}/", nc_href(username, &child_sub));
+            let href = nc_collection_href(username, &child_sub);
             let file_id = resolve_folder_id(file_id_svc, &sf.id).await;
             let oc_id = file_id.map(|id| format_oc_id(id, file_id_svc));
             write_folder_response(
@@ -1047,7 +1117,10 @@ pub fn write_folder_response<W: std::io::Write>(
             .unwrap_or_else(Utc::now);
 
     write_text_element(xml, "d:getlastmodified", &modified_at.to_rfc2822())?;
-    write_text_element(xml, "d:getetag", &format!("\"{}\"", folder.id))?;
+    // Route through `FolderDto::etag` (= `Folder::etag()`, currently
+    // the folder UUID — see the entity for the documented v1 formula
+    // and the follow-up plan to make it descendant-aware).
+    write_text_element(xml, "d:getetag", &format!("\"{}\"", folder.etag))?;
     write_text_element(xml, "d:getcontenttype", "httpd/unix-directory")?;
     write_text_element(xml, "d:getcontentlength", "0")?;
     write_text_element(xml, "d:creationdate", &created_at.to_rfc3339())?;
@@ -1277,6 +1350,41 @@ mod tests {
         assert!(href.contains("file%231.txt"));
     }
 
+    // ── nc_collection_href ──
+    // RFC 4918 §5.2 requires a collection URL to end in '/'. The NC
+    // desktop client at `networkjobs.cpp:234` aborts the PROPFIND
+    // parse with `Invalid href "<…>" expected starting with
+    // "<requested-url>"` if the own-entry href is missing the slash.
+    // These tests pin the helper's behaviour so the regression can't
+    // come back silently.
+
+    #[test]
+    fn test_collection_href_appends_slash_when_missing() {
+        assert_eq!(
+            nc_collection_href("alice", "ext"),
+            "/remote.php/dav/files/alice/ext/"
+        );
+    }
+
+    #[test]
+    fn test_collection_href_idempotent_at_root() {
+        // Root subpath already ends in '/' — don't double-append.
+        assert_eq!(
+            nc_collection_href("alice", ""),
+            "/remote.php/dav/files/alice/"
+        );
+    }
+
+    #[test]
+    fn test_collection_href_preserves_encoding() {
+        // Wrapping must not re-encode or double-encode already-encoded
+        // segments.
+        assert_eq!(
+            nc_collection_href("alice", "My Photos/2024"),
+            "/remote.php/dav/files/alice/My%20Photos/2024/"
+        );
+    }
+
     // ── extract_nc_subpath_from_dest ──
 
     #[test]
diff --git a/src/main.rs b/src/main.rs
index 96cf18c5..192b4146 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -451,21 +451,20 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
             .merge(caldav_protected)
             .merge(carddav_protected)
             .merge(webdav_protected)
-            .merge(web_routes)
-            .layer(
-                TraceLayer::new_for_http()
-                    .make_span_with(ClientIpMakeSpan)
-                    .on_response(LogBadRequest),
-            )
-            .layer(PropagateRequestIdLayer::x_request_id())
-            .layer(SetRequestIdLayer::x_request_id(UuidRequestId));
+            .merge(web_routes);
 
-        // Mount Nextcloud routes (uses its own Basic Auth middleware)
+        // Mount Nextcloud routes (uses its own Basic Auth middleware).
+        // **Merged BEFORE the trace + request-id layers** so NC requests
+        // get the same `request_id` / `user_id` / `client_ip` span
+        // fields as every other surface — see
+        // `interfaces/middleware/trace_span.rs::ClientIpMakeSpan`.
         if let Some(nc_router) = nextcloud_router {
             app = app.merge(nc_router.with_state(app_state.clone()));
         }
 
-        // Mount WOPI routes (protocol routes use own token auth, API routes behind auth middleware)
+        // Mount WOPI routes (protocol routes use own token auth, API routes behind auth middleware).
+        // Same reasoning as NC above: merge before the trace layer so
+        // WOPI requests appear in the structured log channel.
         if let Some((wopi_protocol, wopi_api)) = wopi_routes {
             let wopi_api_protected = wopi_api
                 .layer(axum::middleware::from_fn(csrf_middleware))
@@ -477,6 +476,20 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
                 .nest("/wopi", wopi_protocol)
                 .nest("/api/wopi", wopi_api_protected);
         }
+
+        // ── Trace + request-id layers applied LAST so every route
+        //    merged above (including the conditional NC and WOPI
+        //    surfaces) is wrapped. New protocol routers added later
+        //    only have to be merged before this point to get tracing
+        //    for free — no second site to remember to update.
+        app = app
+            .layer(
+                TraceLayer::new_for_http()
+                    .make_span_with(ClientIpMakeSpan)
+                    .on_response(LogBadRequest),
+            )
+            .layer(PropagateRequestIdLayer::x_request_id())
+            .layer(SetRequestIdLayer::x_request_id(UuidRequestId));
     } else {
         // Auth disabled — no middleware applied
         tracing::warn!("Authentication is DISABLED — all API routes are publicly accessible");
@@ -491,7 +504,24 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
             .merge(caldav_router)
             .merge(carddav_router)
             .merge(webdav_router)
-            .merge(web_routes)
+            .merge(web_routes);
+
+        // Mount Nextcloud routes — merged BEFORE the trace + request-id
+        // layers so NC requests get the same span fields as every
+        // other surface (matches the auth-enabled branch above).
+        if let Some(nc_router) = nextcloud_router {
+            app = app.merge(nc_router.with_state(app_state.clone()));
+        }
+
+        // Mount WOPI routes (no auth middleware when auth is disabled).
+        // Same reasoning: merge before the trace layer.
+        if let Some((wopi_protocol, wopi_api)) = wopi_routes {
+            app = app.nest("/wopi", wopi_protocol).nest("/api/wopi", wopi_api);
+        }
+
+        // ── Trace + request-id layers applied LAST. See the
+        //    auth-enabled branch above for the rationale.
+        app = app
             .layer(
                 TraceLayer::new_for_http()
                     .make_span_with(ClientIpMakeSpan)
@@ -499,16 +529,6 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
             )
             .layer(PropagateRequestIdLayer::x_request_id())
             .layer(SetRequestIdLayer::x_request_id(UuidRequestId));
-
-        // Mount Nextcloud routes
-        if let Some(nc_router) = nextcloud_router {
-            app = app.merge(nc_router.with_state(app_state.clone()));
-        }
-
-        // Mount WOPI routes (no auth middleware when auth is disabled)
-        if let Some((wopi_protocol, wopi_api)) = wopi_routes {
-            app = app.nest("/wopi", wopi_protocol).nest("/api/wopi", wopi_api);
-        }
     }
 
     // Increase the default body limit to allow large file uploads.
diff --git a/static/css/components/tooltip.css b/static/css/components/tooltip.css
new file mode 100644
index 00000000..9c0aada3
--- /dev/null
+++ b/static/css/components/tooltip.css
@@ -0,0 +1,95 @@
+/* ── Tooltip primitive ─────────────────────────────────────────────
+ *
+ * Generic on-hover tooltip used app-wide. Two flavours:
+ *
+ *  1. Single-line label, content from `data-tooltip="…"` on the trigger.
+ *     Use `attachTooltip(el, text)` from `static/js/utils/tooltip.js`.
+ *  2. Rich popover with a DOM subtree, populated lazily on first hover.
+ *     Use `attachRichTooltip(el, populateAsync)` for things like the
+ *     group-vignette member list.
+ *
+ * Both are portal'd to `document.body` (the JS helper creates a child
+ * of body and positions it with `position: fixed`) so they escape the
+ * `overflow: hidden` clipping that lives on lane wrappers, list rows,
+ * and any other "contain my children" ancestor. Without the portal,
+ * tooltips near the edges of those containers get cropped — exactly
+ * the bug that prompted this refactor.
+ *
+ * Hover-intent timing is asymmetric on purpose:
+ *  - Entry: 250 ms delay before the fade-in starts. Short enough to
+ *    feel responsive (much faster than the browser-native `title`
+ *    delay, which is ~500–1500 ms), long enough to suppress flicker
+ *    on accidental mouseovers.
+ *  - Exit: 0 ms delay. The tooltip dismisses immediately when the
+ *    user moves away.
+ *
+ * The class toggle is JS-driven (mouseenter/leave + focusin/out
+ * listeners on the trigger); the visible transition lives entirely
+ * in CSS so a setTimeout never gates the visual change.
+ */
+
+.oxi-tooltip-popover {
+    position: fixed;
+    min-width: 0;
+    max-width: 280px;
+    padding: 6px 10px;
+    background-color: var(--color-text);
+    color: var(--color-bg-page);
+    font-size: 12px;
+    line-height: 1.5;
+    text-align: left;
+    border-radius: 6px;
+    box-shadow: 0 2px 8px var(--color-shadow);
+    pointer-events: none;
+    opacity: 0;
+    /* Default (no `--visible`): fast hide, no delay. */
+    transition: opacity 100ms ease-out 0ms;
+    z-index: 10000;
+}
+
+/* Simple (data-tooltip) flavour — keeps the label on one line so it
+   reads as a short caption, not a paragraph. Used by short labels
+   like a user vignette's email-on-hover. */
+.oxi-tooltip-popover--simple {
+    white-space: nowrap;
+    max-width: none;
+}
+
+/* Visible state overrides the transition to add the hover-intent
+   delay on the *entry* path. Removing the class falls back to
+   the default rule above (no delay → immediate fade-out). */
+.oxi-tooltip-popover--visible {
+    opacity: 1;
+    transition: opacity 100ms ease-out 250ms;
+}
+
+/* ── Rich-popover layout helpers ────────────────────────────────── */
+
+.oxi-tooltip-popover__line {
+    overflow: hidden;
+    text-overflow: ellipsis;
+    white-space: nowrap;
+}
+
+/* "+N" overflow badge — small pill at the end of a list of items when
+   there are more than the tooltip cares to show. Lighter background
+   so the count reads as meta-information, not just another line. */
+.oxi-tooltip-popover__overflow {
+    display: inline-block;
+    margin-top: 4px;
+    padding: 1px 7px;
+    font-size: 11px;
+    font-weight: 600;
+    color: var(--color-bg-page);
+    background-color: var(--color-text-faint);
+    border-radius: 9999px;
+}
+
+/* Placeholder line shown briefly between the first hover and the
+   populate() callback's resolve (e.g. while `/api/groups/{id}/members`
+   is in flight). Italic + dimmed so the user perceives it as a
+   transitional state, not real content. */
+.oxi-tooltip-popover__placeholder {
+    color: var(--color-text-faint);
+    font-style: italic;
+}
diff --git a/static/css/components/userVignette.css b/static/css/components/userVignette.css
index b4f52f5f..d4b75978 100644
--- a/static/css/components/userVignette.css
+++ b/static/css/components/userVignette.css
@@ -21,6 +21,12 @@
     overflow: hidden;
 }
 
+/* The on-hover email tooltip (used by `createUserVignette` when the
+   email is set) and the rich group-members popover both live in
+   `components/tooltip.css` and are attached at runtime via
+   `static/js/utils/tooltip.js` — kept generic so other surfaces
+   (role chips, link chips, action buttons) can opt in the same way. */
+
 .user-vignette__avatar {
     border-radius: 50%;
     display: flex;
diff --git a/static/css/main.css b/static/css/main.css
index 660aa9b7..b1ba10cd 100644
--- a/static/css/main.css
+++ b/static/css/main.css
@@ -23,6 +23,7 @@
 @import url("./components/shareDialog.css");
 @import url("./components/shareModal.css");
 @import url("./components/groupsModal.css");
+@import url("./components/tooltip.css");
 @import url("./components/userVignette.css");
 @import url("./components/linkChip.css");
 @import url("./components/uploadDropdown.css");
diff --git a/static/js/app/main.js b/static/js/app/main.js
index 8e1e6678..2972b8ae 100644
--- a/static/js/app/main.js
+++ b/static/js/app/main.js
@@ -540,8 +540,15 @@ function initApp() {
         grants.fetchIncomingGrants();
         grants.fetchOutgoingGrants();
 
-        switchSectionTo(hashContext.section);
         if (hashContext.section === 'files') {
+            // Capture the URL-derived path BEFORE the section switch.
+            // `switchToFilesSection` resets `app.currentPath` to home
+            // by default and kicks off its own `loadFiles()` — if we
+            // wrote the hash-derived path AFTER the switch, our write
+            // would race the load-already-in-flight and lose, taking
+            // the user back to root on every other refresh. Setting
+            // first + `preservePath: true` makes the switch's load
+            // start with the correct path.
             if (hashContext.path) {
                 console.log(`init: reusing folder from hash URL: ${hashContext.path}`);
                 app.currentPath = hashContext.path;
@@ -551,7 +558,11 @@ function initApp() {
                 app.viewFile = hashContext.file;
             }
 
-            loadFiles();
+            switchToFilesSection({ preservePath: true });
+            // `switchToFilesSection` already calls `loadFiles()` — do
+            // not call it again here, that would race itself.
+        } else {
+            switchSectionTo(hashContext.section);
         }
     });
 
diff --git a/static/js/app/navigation.js b/static/js/app/navigation.js
index 88b0e64a..a3791bf2 100644
--- a/static/js/app/navigation.js
+++ b/static/js/app/navigation.js
@@ -270,7 +270,20 @@ function switchToSharedWithMeSection() {
     sharedWithMeView.init();
 }
 
-function switchToFilesSection() {
+/**
+ * Switch the UI into the Files section.
+ *
+ * @param {Object}  [options]
+ * @param {boolean} [options.preservePath=false]
+ *   When true, keep the current `app.currentPath` instead of resetting
+ *   to the home folder. Used on initial page load with a hash-driven
+ *   path (e.g. `#/files/folder/<uuid>`) so the section switch doesn't
+ *   clobber the path the caller has just set from the URL. Without
+ *   this flag, the unconditional reset races with `loadFiles()`
+ *   (which is also kicked off from here) and the home-folder URL
+ *   wins, redirecting the user back to root on every other refresh.
+ */
+function switchToFilesSection({ preservePath = false } = {}) {
     if (!setCurrentSection('files')) return;
 
     // Set actions bar mode
@@ -299,12 +312,13 @@ function switchToFilesSection() {
     //reset files view + remove any error
     ui.resetFilesList();
 
-    // Reset to home folder and update breadcrumb. External users have no
-    // home — leave `currentPath` as the caller set it (e.g. the magic-link
+    // Reset to home folder unless the caller has pre-set a path (the
+    // `preservePath` opt-in). External users have no home — leave
+    // `currentPath` as the caller set it (e.g. the magic-link
     // landing's hash context) so loadFiles() doesn't fall through to
-    // `/api/folders//resources`. If `currentPath` is still empty by the
-    // time loadFiles() runs, it self-redirects to /#/sharedwithme.
-    if (!app.isExternalUser) {
+    // `/api/folders//resources`. If `currentPath` is still empty by
+    // the time loadFiles() runs, it self-redirects to /#/sharedwithme.
+    if (!app.isExternalUser && !preservePath) {
         app.currentPath = app.userHomeFolderId || '';
         app.breadcrumbPath = [];
     }
diff --git a/static/js/components/groupVignette.js b/static/js/components/groupVignette.js
index b395eb56..7e1fa671 100644
--- a/static/js/components/groupVignette.js
+++ b/static/js/components/groupVignette.js
@@ -17,6 +17,142 @@
  */
 
 import { escapeHtml } from '../core/formatters.js';
+import { i18n } from '../core/i18n.js';
+import { groups, INTERNAL_GROUP_ID } from '../model/groups.js';
+import { systemUsers } from '../model/systemUsers.js';
+import { attachRichTooltip, OxiTooltipClass } from '../utils/tooltip.js';
+
+/** Max member names displayed in the on-hover tooltip; any extra count
+ *  surfaces as a "+N" badge on the last line. Kept small enough to fit
+ *  inside the 280 px tooltip without scrolling, large enough to be
+ *  informative for the typical share-with-a-team case. */
+const MAX_MEMBERS_IN_TOOLTIP = 8;
+
+/**
+ * Session-scoped cache of resolved member lists, keyed by group UUID.
+ * One entry per group ever hovered; the promise is reused across
+ * subsequent vignettes for the same group so a list of 50 rows that
+ * all reference the same group hits `/api/groups/{id}/members` once.
+ *
+ * @type {Map<string, Promise<{ names: string[], total: number }>>}
+ */
+const _membersCache = new Map();
+
+/**
+ * Resolve the first N direct members of a group to display names.
+ * Idempotent + memoised across vignettes that share a group id.
+ *
+ * Failures (403 on a group the caller can't list, 404 on a stale id,
+ * network errors) resolve to an empty-names + zero-total shape so the
+ * UI shows a graceful "no members" placeholder instead of throwing.
+ *
+ * @param {string} groupId
+ * @returns {Promise<{ names: string[], total: number }>}
+ */
+async function _resolveGroupMembers(groupId) {
+    const cached = _membersCache.get(groupId);
+    if (cached) return cached;
+
+    const promise = (async () => {
+        /** @type {import('../core/types.js').GroupMemberItem[]} */
+        let members;
+        try {
+            members = await groups.listMembers(groupId);
+        } catch {
+            return { names: [], total: 0 };
+        }
+        const total = members.length;
+        // Only resolve the names we'll actually display — the "+N more"
+        // badge counts the rest from `total - MAX`. Cuts down on the
+        // number of /api/users/{id} backfills for big groups.
+        const slice = members.slice(0, MAX_MEMBERS_IN_TOOLTIP);
+
+        // Parallelise the per-member name lookups so a 8-member group
+        // resolves in one round-trip's worth of latency, not eight.
+        const names = await Promise.all(
+            slice.map(async (m) => {
+                if (m.kind === 'user') {
+                    try {
+                        return await systemUsers.getDisplayName(m.id);
+                    } catch {
+                        return `${m.id.slice(0, 8)}…`;
+                    }
+                }
+                // Nested group — resolve via groups model.
+                try {
+                    const resolved = await groups.resolveGroups([m.id]);
+                    const g = resolved?.[m.id];
+                    if (g?.name) return `👥 ${g.name}`;
+                } catch {
+                    // fall through
+                }
+                return `👥 ${m.id.slice(0, 8)}…`;
+            })
+        );
+        return { names, total };
+    })();
+
+    _membersCache.set(groupId, promise);
+    return promise;
+}
+
+/**
+ * Attach the on-hover member popover to a group vignette. Delegates
+ * positioning + show/hide + portal placement to the generic
+ * `attachRichTooltip` helper (see `utils/tooltip.js`); this function
+ * just owns the per-row content — the placeholder, the member lines,
+ * and the "+N" overflow badge.
+ *
+ * @param {HTMLElement} vignetteEl  the wrapper returned by `createGroupVignette`
+ * @param {string}      groupId     UUID of the group whose members to show
+ */
+function _attachMembersTooltip(vignetteEl, groupId) {
+    attachRichTooltip(vignetteEl, async (pop) => {
+        // Placeholder shown until the network resolves. Slow connections
+        // see "Loading members…" instead of an empty box.
+        const placeholder = document.createElement('div');
+        placeholder.className = OxiTooltipClass.PLACEHOLDER;
+        placeholder.textContent = i18n.t('groups.members_loading', 'Loading members…');
+        pop.appendChild(placeholder);
+
+        const { names, total } = await _resolveGroupMembers(groupId);
+        pop.replaceChildren();
+
+        if (total === 0) {
+            const empty = document.createElement('div');
+            empty.className = OxiTooltipClass.PLACEHOLDER;
+            // Special case: the built-in "Internal" virtual group has
+            // implicit membership — it represents every internal user
+            // on this server. `listMembers` returns an empty array
+            // because no explicit rows exist in `auth.subject_group_members`,
+            // but "No members" would mislead. Surface the real meaning
+            // instead. Future virtual groups with implicit membership
+            // (e.g. "Everyone") would extend this branch.
+            empty.textContent =
+                groupId === INTERNAL_GROUP_ID
+                    ? i18n.t('groups.virtual_internal_explanation', 'Every internal user on this server')
+                    : i18n.t('groups.members_empty', 'No members');
+            pop.appendChild(empty);
+            return;
+        }
+        for (const name of names) {
+            const line = document.createElement('div');
+            line.className = OxiTooltipClass.LINE;
+            line.textContent = name;
+            pop.appendChild(line);
+        }
+        if (total > MAX_MEMBERS_IN_TOOLTIP) {
+            const overflow = document.createElement('div');
+            overflow.className = OxiTooltipClass.LINE;
+            // Inner badge so the "+N" reads as a count, not another name.
+            const badge = document.createElement('span');
+            badge.className = OxiTooltipClass.OVERFLOW;
+            badge.textContent = `+${total - MAX_MEMBERS_IN_TOOLTIP}`;
+            overflow.append('… ', badge);
+            pop.appendChild(overflow);
+        }
+    });
+}
 
 /**
  * Build the inline vignette.
@@ -26,17 +162,25 @@ import { escapeHtml } from '../core/formatters.js';
  * @param {'xs'|'sm'|'md'|'list'} [size='sm']
  *   Matches the size scale of `createUserVignette`. The size class is
  *   `user-vignette--${size}`; see `static/css/components/userVignette.css`.
- * @param {{ icon?: string }} [opts]
+ * @param {{ icon?: string, groupId?: string }} [opts]
  *   `icon`: FA class string without the `fa-` prefix (defaults to
  *   `'fa-user-group'`). Used to signal virtual groups visually — see
  *   `groupIconClass()` / `groupIconClassByVirtual()` in `./groupDisplay.js`
  *   return a distinct icon for system-wide virtual groups (Internal,
  *   future Everyone, …).
+ *
+ *   `groupId`: UUID of the group. When supplied, hovering the vignette
+ *   reveals a tooltip listing up to {@link MAX_MEMBERS_IN_TOOLTIP}
+ *   member names with a `+N` badge for overflow. The member list is
+ *   fetched lazily on first hover, memoised across all vignettes that
+ *   share the same id, so a row of 50 grants pointing at the same
+ *   team only hits `/api/groups/{id}/members` once.
  * @returns {HTMLElement}
  */
-export function createGroupVignette(name, size = 'sm', { icon = 'fa-user-group' } = {}) {
+export function createGroupVignette(name, size = 'sm', { icon = 'fa-user-group', groupId } = {}) {
     const el = document.createElement('div');
     el.className = `user-vignette user-vignette-group user-vignette--${size}`;
     el.innerHTML = `<span class="user-vignette__avatar"><i class="fas ${escapeHtml(icon)}"></i></span><span class="user-vignette__name">${escapeHtml(name)}</span>`;
+    if (groupId) _attachMembersTooltip(el, groupId);
     return el;
 }
diff --git a/static/js/components/mySharesList.js b/static/js/components/mySharesList.js
index e079837f..6c374406 100644
--- a/static/js/components/mySharesList.js
+++ b/static/js/components/mySharesList.js
@@ -270,7 +270,8 @@ class MySharesList {
         }
         if (swimKey.startsWith('group:')) {
             return createGroupVignette(this._groupName(grant.subject_id), 'list', {
-                icon: this._groupIcon(grant.subject_id)
+                icon: this._groupIcon(grant.subject_id),
+                groupId: grant.subject_id
             });
         }
         const el = document.createElement('div');
@@ -347,7 +348,8 @@ class MySharesList {
         } else if (grant.subject_type === 'group') {
             el.appendChild(
                 createGroupVignette(this._groupName(grant.subject_id), 'xs', {
-                    icon: this._groupIcon(grant.subject_id)
+                    icon: this._groupIcon(grant.subject_id),
+                    groupId: grant.subject_id
                 })
             );
         } else {
diff --git a/static/js/components/userVignette.js b/static/js/components/userVignette.js
index a760cc9a..ba1438fc 100644
--- a/static/js/components/userVignette.js
+++ b/static/js/components/userVignette.js
@@ -20,6 +20,7 @@
  */
 
 import { systemUsers } from '../model/systemUsers.js';
+import { attachTooltip } from '../utils/tooltip.js';
 
 // ── Helpers ────────────────────────────────────────────────────────────────────
 
@@ -167,12 +168,23 @@ export function createUserVignette(userId, size = 'sm', { showName = true, showE
     ]).then(([name, photo, email, isExternal]) => {
         if (nameEl) nameEl.textContent = name;
         if (emailEl) emailEl.textContent = email ?? '';
-        // Tooltip: surface the email on hover when it's not already
-        // rendered as the visible label (showEmail mode) and isn't
-        // already the displayed name (the fallback case where the user
-        // has no given/family/username and the label IS the email).
-        if (email && !showEmail && email !== name) {
-            wrapper.title = email;
+        // Tooltip: surface the email on hover for every vignette that
+        // has one — including external users whose visible label IS
+        // the email already. The redundant "alice@x.com → alice@x.com"
+        // hover is a small price for keeping the interaction uniform:
+        // every user row in a list reacts to hover the same way, so
+        // the user doesn't learn "internal rows have tooltips, external
+        // rows are silent". Suppressed only in `showEmail` mode, where
+        // the email is already a permanent line below the name.
+        //
+        // `attachTooltip` portals the popover to `document.body` and
+        // applies the shared 250 ms hover-intent delay (much faster
+        // than the native `title` attribute's ~500–1500 ms wait).
+        // `aria-label` is set in parallel so screen readers still get
+        // the email — popover content is mouse/keyboard-hover only.
+        if (email && !showEmail) {
+            wrapper.setAttribute('aria-label', email);
+            attachTooltip(wrapper, email);
         }
         if (photo) {
             _applyPhoto(avatar, photo, name);
diff --git a/static/js/core/types.js b/static/js/core/types.js
index 4c16fca2..99ba6f02 100644
--- a/static/js/core/types.js
+++ b/static/js/core/types.js
@@ -25,6 +25,7 @@
  * @property {string} owner_id
  * @property {string|null} parent_id the folder parent (null if is_root)
  * @property {string} path the full path
+ * @property {string} etag opaque HTTP ETag, for If-Match / If-None-Match
  */
 
 //FIXME: rename into FileItem
@@ -44,6 +45,8 @@
  * @property {number} size
  * @property {string} size_formatted
  * @property {number} sort_date
+ * @property {string} etag opaque HTTP ETag, for If-Match / If-None-Match
+ * @property {string} content_hash raw BLAKE3 content hash, for dedup checks
  */
 
 /**
diff --git a/static/js/utils/tooltip.js b/static/js/utils/tooltip.js
new file mode 100644
index 00000000..dc16bc78
--- /dev/null
+++ b/static/js/utils/tooltip.js
@@ -0,0 +1,232 @@
+// @ts-check
+
+/**
+ * Generic tooltip helper used app-wide.
+ *
+ * Two flavours:
+ *
+ *  - {@link attachTooltip}      — short text label, optionally populated
+ *                                 from a `data-tooltip` attribute. Use
+ *                                 for one-liners (the email-on-hover on
+ *                                 a user vignette, the title-text on a
+ *                                 chip / button, etc.).
+ *  - {@link attachRichTooltip}  — structured DOM populated lazily on
+ *                                 first hover. Use when the content is
+ *                                 multi-line, async-fetched, or needs
+ *                                 inner styling (e.g. the member list
+ *                                 in a group vignette).
+ *
+ * Both portal the popover to `document.body` and position it with
+ * `position: fixed` so it escapes every ancestor `overflow: hidden`
+ * clip in the page. This is the only reliable cross-browser way to
+ * keep tooltips fully visible from triggers buried inside list rows,
+ * scroll containers, or modal panels.
+ *
+ * The class toggle (`oxi-tooltip-popover--visible`) is JS-driven on
+ * `mouseenter` / `mouseleave` / `focusin` / `focusout`. The hover-intent
+ * delay (250 ms before fade-in, 0 ms before fade-out) lives entirely
+ * in the CSS transition rules — never in a JS `setTimeout`. See
+ * `static/css/components/tooltip.css` for the timing source of truth.
+ *
+ * Layout helpers exported for the rich variant:
+ *  - `OxiTooltipClass.LINE`      — apply to each row inside the popover
+ *  - `OxiTooltipClass.OVERFLOW`  — small "+N" badge for truncated lists
+ *  - `OxiTooltipClass.PLACEHOLDER` — italic dimmed text for loading /
+ *                                    empty states
+ */
+
+const POPOVER_CLASS = 'oxi-tooltip-popover';
+const VISIBLE_CLASS = 'oxi-tooltip-popover--visible';
+const SIMPLE_CLASS = 'oxi-tooltip-popover--simple';
+
+/** Class names exported so callers can build the popover body with the
+ *  layout helpers without dragging in private CSS module conventions. */
+export const OxiTooltipClass = Object.freeze({
+    LINE: 'oxi-tooltip-popover__line',
+    OVERFLOW: 'oxi-tooltip-popover__overflow',
+    PLACEHOLDER: 'oxi-tooltip-popover__placeholder'
+});
+
+/** Distance between the tooltip and the trigger edge, in pixels. */
+const GAP = 6;
+
+/** Inset from the viewport edges when clamping the tooltip position. */
+const MARGIN = 8;
+
+/**
+ * Position `popover` above (or below, when there isn't room above) the
+ * given trigger element. Uses `position: fixed` so it escapes any
+ * ancestor `overflow: hidden`. Clamps horizontally and vertically into
+ * the viewport so tooltips near the edges still read cleanly.
+ *
+ * @param {HTMLElement} popover
+ * @param {HTMLElement} triggerEl
+ */
+function _positionPopover(popover, triggerEl) {
+    const triggerRect = triggerEl.getBoundingClientRect();
+    // Measure after content has been added so we know the final size.
+    const popRect = popover.getBoundingClientRect();
+    const vw = window.innerWidth;
+    const vh = window.innerHeight;
+
+    // Vertical: prefer above the trigger. Flip below when there's not
+    // enough room above.
+    let top = triggerRect.top - popRect.height - GAP;
+    if (top < MARGIN) {
+        top = triggerRect.bottom + GAP;
+    }
+
+    // Horizontal: center on the trigger, clamp into the viewport.
+    let left = triggerRect.left + triggerRect.width / 2 - popRect.width / 2;
+    if (left < MARGIN) left = MARGIN;
+    if (left + popRect.width > vw - MARGIN) left = vw - popRect.width - MARGIN;
+
+    // Final vertical clamp — covers the (very rare) case where the
+    // tooltip is taller than the visible viewport.
+    if (top + popRect.height > vh - MARGIN) top = vh - popRect.height - MARGIN;
+    if (top < MARGIN) top = MARGIN;
+
+    popover.style.top = `${top}px`;
+    popover.style.left = `${left}px`;
+}
+
+/**
+ * Internal: wire mouseenter/leave + focusin/out listeners on `triggerEl`,
+ * lazily create the popover element on first hover, and call `populate`
+ * once to fill it. Returns a cleanup function that removes the
+ * listeners and the popover element.
+ *
+ * @param {HTMLElement} triggerEl
+ * @param {(popover: HTMLElement) => void | Promise<void>} populate
+ *   Called exactly once when the popover is first shown. Synchronous
+ *   populates take effect immediately; async populates show the
+ *   placeholder span (if you created one) until the promise resolves,
+ *   after which the popover is re-positioned to account for size
+ *   changes.
+ * @param {{ simple?: boolean }} [opts]
+ *   `simple`: add the `--simple` modifier so the popover uses the
+ *   single-line label style (white-space: nowrap, no min-width).
+ * @returns {() => void}  Cleanup; idempotent.
+ */
+function _attach(triggerEl, populate, opts = {}) {
+    /** @type {HTMLElement | null} */
+    let popover = null;
+    let populated = false;
+    let detached = false;
+
+    const ensurePopover = () => {
+        if (popover) return popover;
+        popover = document.createElement('div');
+        popover.className = POPOVER_CLASS + (opts.simple ? ` ${SIMPLE_CLASS}` : '');
+        // ARIA: behave like a tooltip for screen readers — though we
+        // also rely on `aria-label` / surrounding text since hover
+        // isn't reachable via keyboard-only assistive tech.
+        popover.setAttribute('role', 'tooltip');
+        document.body.appendChild(popover);
+        return popover;
+    };
+
+    const show = () => {
+        if (detached) return;
+        const pop = ensurePopover();
+
+        if (!populated) {
+            populated = true;
+            // Synchronous populate paths render immediately. Async
+            // populates (those returning a Promise) re-position after
+            // resolve so the tooltip catches up to its final size —
+            // important when the placeholder text is much narrower
+            // than the eventual content.
+            const result = populate(pop);
+            if (result && typeof (/** @type {Promise<void>} */ (result).then) === 'function') {
+                /** @type {Promise<void>} */ (result).then(() => {
+                    if (popover?.classList.contains(VISIBLE_CLASS)) {
+                        _positionPopover(popover, triggerEl);
+                    }
+                });
+            }
+        }
+
+        _positionPopover(pop, triggerEl);
+        pop.classList.add(VISIBLE_CLASS);
+    };
+
+    const hide = () => {
+        if (popover) popover.classList.remove(VISIBLE_CLASS);
+    };
+
+    triggerEl.addEventListener('mouseenter', show);
+    triggerEl.addEventListener('mouseleave', hide);
+    triggerEl.addEventListener('focusin', show);
+    triggerEl.addEventListener('focusout', hide);
+
+    return () => {
+        if (detached) return;
+        detached = true;
+        triggerEl.removeEventListener('mouseenter', show);
+        triggerEl.removeEventListener('mouseleave', hide);
+        triggerEl.removeEventListener('focusin', show);
+        triggerEl.removeEventListener('focusout', hide);
+        popover?.remove();
+        popover = null;
+    };
+}
+
+/**
+ * Attach a simple single-line tooltip to `triggerEl`.
+ *
+ * @param {HTMLElement} triggerEl
+ * @param {string}      text   The label to display.
+ * @returns {() => void}        Cleanup function; idempotent.
+ *
+ * @example
+ *   attachTooltip(emailBadgeEl, 'alice@example.com');
+ */
+export function attachTooltip(triggerEl, text) {
+    return _attach(
+        triggerEl,
+        (pop) => {
+            pop.textContent = text;
+        },
+        { simple: true }
+    );
+}
+
+/**
+ * Attach a rich tooltip with structured DOM populated lazily on first
+ * hover. The `populate` callback receives the popover element and can
+ * append whatever children it wants. Return a Promise to populate
+ * async — the popover re-positions on resolve.
+ *
+ * @param {HTMLElement} triggerEl
+ * @param {(popover: HTMLElement) => void | Promise<void>} populate
+ * @returns {() => void}  Cleanup function; idempotent.
+ *
+ * @example
+ *   attachRichTooltip(groupEl, async (pop) => {
+ *       const placeholder = document.createElement('div');
+ *       placeholder.className = OxiTooltipClass.PLACEHOLDER;
+ *       placeholder.textContent = i18n.t('groups.members_loading');
+ *       pop.appendChild(placeholder);
+ *       const members = await fetchMembers(groupId);
+ *       pop.replaceChildren(); // drop the placeholder
+ *       for (const name of members.slice(0, 8)) {
+ *           const line = document.createElement('div');
+ *           line.className = OxiTooltipClass.LINE;
+ *           line.textContent = name;
+ *           pop.appendChild(line);
+ *       }
+ *       if (members.length > 8) {
+ *           const overflow = document.createElement('div');
+ *           overflow.className = OxiTooltipClass.LINE;
+ *           const badge = document.createElement('span');
+ *           badge.className = OxiTooltipClass.OVERFLOW;
+ *           badge.textContent = `+${members.length - 8}`;
+ *           overflow.append('… ', badge);
+ *           pop.appendChild(overflow);
+ *       }
+ *   });
+ */
+export function attachRichTooltip(triggerEl, populate) {
+    return _attach(triggerEl, populate);
+}
diff --git a/static/js/views/favorites/favoritesView.js b/static/js/views/favorites/favoritesView.js
index 79d82b0a..4a81cc90 100644
--- a/static/js/views/favorites/favoritesView.js
+++ b/static/js/views/favorites/favoritesView.js
@@ -377,7 +377,8 @@ const favoritesView = {
                         sort_date: toSecs(item.favorited_at),
                         icon_class: f.icon_class,
                         icon_special_class: f.icon_special_class ?? '',
-                        category: 'Folder'
+                        category: 'Folder',
+                        etag: ''
                     })
                 );
             } else if (item.resource_type === 'file') {
@@ -397,7 +398,9 @@ const favoritesView = {
                         sort_date: toSecs(item.favorited_at),
                         icon_class: f.icon_class,
                         icon_special_class: f.icon_special_class ?? '',
-                        category: f.category
+                        category: f.category,
+                        etag: '',
+                        content_hash: ''
                     })
                 );
             }
diff --git a/static/js/views/recent/recentView.js b/static/js/views/recent/recentView.js
index 44fa0446..62fcdcb1 100644
--- a/static/js/views/recent/recentView.js
+++ b/static/js/views/recent/recentView.js
@@ -384,7 +384,8 @@ const recentView = {
                         sort_date: toSecs(item.accessed_at),
                         icon_class: f.icon_class,
                         icon_special_class: f.icon_special_class ?? '',
-                        category: 'Folder'
+                        category: 'Folder',
+                        etag: ''
                     })
                 );
             } else if (item.resource_type === 'file') {
@@ -404,7 +405,9 @@ const recentView = {
                         sort_date: toSecs(item.accessed_at),
                         icon_class: f.icon_class,
                         icon_special_class: f.icon_special_class ?? '',
-                        category: f.category
+                        category: f.category,
+                        etag: '',
+                        content_hash: ''
                     })
                 );
             }
diff --git a/static/js/views/sharedWithMe/sharedWithMeView.js b/static/js/views/sharedWithMe/sharedWithMeView.js
index 6bdacdcc..05fde699 100644
--- a/static/js/views/sharedWithMe/sharedWithMeView.js
+++ b/static/js/views/sharedWithMe/sharedWithMeView.js
@@ -386,7 +386,8 @@ const sharedWithMeView = {
                         sort_date: grantedAtSecs(item.granted_at),
                         icon_class: f.icon_class,
                         icon_special_class: f.icon_special_class ?? '',
-                        category: 'folder'
+                        category: 'folder',
+                        etag: ''
                     })
                 );
             } else if (item.resource_type === 'file') {
@@ -406,7 +407,9 @@ const sharedWithMeView = {
                         sort_date: grantedAtSecs(item.granted_at),
                         icon_class: f.icon_class,
                         icon_special_class: f.icon_special_class ?? '',
-                        category: f.category
+                        category: f.category,
+                        etag: '',
+                        content_hash: ''
                     })
                 );
             }
diff --git a/static/js/views/trash/trashView.js b/static/js/views/trash/trashView.js
index 476843b3..0a6b430d 100644
--- a/static/js/views/trash/trashView.js
+++ b/static/js/views/trash/trashView.js
@@ -393,7 +393,8 @@ const trashView = {
                         deletion_date: item.deletion_date,
                         icon_class: f.icon_class,
                         icon_special_class: f.icon_special_class ?? '',
-                        category: 'Folder'
+                        category: 'Folder',
+                        etag: ''
                     })
                 );
             } else if (item.resource_type === 'file') {
@@ -417,7 +418,9 @@ const trashView = {
                         deletion_date: item.deletion_date,
                         icon_class: f.icon_class,
                         icon_special_class: f.icon_special_class ?? '',
-                        category: f.category
+                        category: f.category,
+                        etag: '',
+                        content_hash: ''
                     })
                 );
             }
diff --git a/static/locales/ar.json b/static/locales/ar.json
index fa1cb9c3..559f0a8b 100644
--- a/static/locales/ar.json
+++ b/static/locales/ar.json
@@ -867,7 +867,10 @@
         "member_count_other": "{count} أعضاء",
         "delete_confirm_label": "اكتب اسم المجموعة للتأكيد:",
         "delete_confirm_mismatch": "اكتب اسم المجموعة كما هو للتأكيد.",
-        "virtual_internal_name": "داخلي"
+        "virtual_internal_name": "داخلي",
+        "members_loading": "جارٍ تحميل الأعضاء…",
+        "members_empty": "لا يوجد أعضاء",
+        "virtual_internal_explanation": "كل مستخدم داخلي على هذا الخادم"
     },
     "myshares": {
         "copyLink": "نسخ الرابط",
diff --git a/static/locales/de.json b/static/locales/de.json
index 984cadf2..ee333f84 100644
--- a/static/locales/de.json
+++ b/static/locales/de.json
@@ -867,7 +867,10 @@
         "member_count_other": "{count} Mitglieder",
         "delete_confirm_label": "Tippe den Gruppennamen zur Bestätigung ein:",
         "delete_confirm_mismatch": "Tippe den Gruppennamen exakt zur Bestätigung ein.",
-        "virtual_internal_name": "Intern"
+        "virtual_internal_name": "Intern",
+        "members_loading": "Mitglieder werden geladen…",
+        "members_empty": "Keine Mitglieder",
+        "virtual_internal_explanation": "Jeder interne Benutzer auf diesem Server"
     },
     "myshares": {
         "copyLink": "Link kopieren",
diff --git a/static/locales/en.json b/static/locales/en.json
index a606b0fa..7e0fa4b7 100644
--- a/static/locales/en.json
+++ b/static/locales/en.json
@@ -862,6 +862,8 @@
         "name_placeholder": "engineering",
         "description_label": "Description (optional)",
         "members_section": "Members",
+        "members_loading": "Loading members…",
+        "members_empty": "No members",
         "add_member_placeholder": "Add a user or group…",
         "no_members": "No members yet.",
         "remove_member": "Remove",
@@ -877,6 +879,7 @@
         "member_count_other": "{count} members",
         "delete_confirm_label": "Type the group name to confirm:",
         "delete_confirm_mismatch": "Type the group name exactly to confirm.",
-        "virtual_internal_name": "Internal"
+        "virtual_internal_name": "Internal",
+        "virtual_internal_explanation": "Every internal user on this server"
     }
 }
diff --git a/static/locales/es.json b/static/locales/es.json
index 01657b03..d4baccf5 100644
--- a/static/locales/es.json
+++ b/static/locales/es.json
@@ -867,7 +867,10 @@
         "member_count_other": "{count} miembros",
         "delete_confirm_label": "Escribe el nombre del grupo para confirmar:",
         "delete_confirm_mismatch": "Escribe el nombre del grupo exactamente para confirmar.",
-        "virtual_internal_name": "Interno"
+        "virtual_internal_name": "Interno",
+        "members_loading": "Cargando miembros…",
+        "members_empty": "Sin miembros",
+        "virtual_internal_explanation": "Todos los usuarios internos de este servidor"
     },
     "myshares": {
         "copyLink": "Copiar enlace",
diff --git a/static/locales/fa.json b/static/locales/fa.json
index 61ab2a56..58b745c1 100644
--- a/static/locales/fa.json
+++ b/static/locales/fa.json
@@ -867,7 +867,10 @@
         "member_count_other": "{count} عضو",
         "delete_confirm_label": "نام گروه را برای تأیید وارد کنید:",
         "delete_confirm_mismatch": "نام گروه را دقیقاً برای تأیید وارد کنید.",
-        "virtual_internal_name": "داخلی"
+        "virtual_internal_name": "داخلی",
+        "members_loading": "در حال بارگیری اعضا…",
+        "members_empty": "بدون عضو",
+        "virtual_internal_explanation": "هر کاربر داخلی روی این سرور"
     },
     "myshares": {
         "copyLink": "کپی پیوند",
diff --git a/static/locales/fr.json b/static/locales/fr.json
index 51c4afa5..e161f541 100644
--- a/static/locales/fr.json
+++ b/static/locales/fr.json
@@ -867,7 +867,10 @@
         "member_count_other": "{count} membres",
         "delete_confirm_label": "Tapez le nom du groupe pour confirmer :",
         "delete_confirm_mismatch": "Tapez le nom du groupe exactement pour confirmer.",
-        "virtual_internal_name": "Interne"
+        "virtual_internal_name": "Interne",
+        "members_loading": "Chargement des membres…",
+        "members_empty": "Aucun membre",
+        "virtual_internal_explanation": "Tous les utilisateurs internes de ce serveur"
     },
     "myshares": {
         "copyLink": "Copier le lien",
diff --git a/static/locales/hi.json b/static/locales/hi.json
index 62b4dda1..e451ecdb 100644
--- a/static/locales/hi.json
+++ b/static/locales/hi.json
@@ -867,7 +867,10 @@
         "member_count_other": "{count} सदस्य",
         "delete_confirm_label": "पुष्टि के लिए समूह का नाम लिखें:",
         "delete_confirm_mismatch": "पुष्टि के लिए समूह का नाम बिल्कुल वैसा ही लिखें।",
-        "virtual_internal_name": "आंतरिक"
+        "virtual_internal_name": "आंतरिक",
+        "members_loading": "सदस्य लोड हो रहे हैं…",
+        "members_empty": "कोई सदस्य नहीं",
+        "virtual_internal_explanation": "इस सर्वर पर हर आंतरिक उपयोगकर्ता"
     },
     "myshares": {
         "copyLink": "लिंक कॉपी करें",
diff --git a/static/locales/it.json b/static/locales/it.json
index 0d3860d2..e16e50b1 100644
--- a/static/locales/it.json
+++ b/static/locales/it.json
@@ -867,7 +867,10 @@
         "member_count_other": "{count} membri",
         "delete_confirm_label": "Digita il nome del gruppo per confermare:",
         "delete_confirm_mismatch": "Digita esattamente il nome del gruppo per confermare.",
-        "virtual_internal_name": "Interno"
+        "virtual_internal_name": "Interno",
+        "members_loading": "Caricamento membri…",
+        "members_empty": "Nessun membro",
+        "virtual_internal_explanation": "Ogni utente interno su questo server"
     },
     "myshares": {
         "copyLink": "Copia link",
diff --git a/static/locales/ja.json b/static/locales/ja.json
index 84debb3f..25beab40 100644
--- a/static/locales/ja.json
+++ b/static/locales/ja.json
@@ -867,7 +867,10 @@
         "member_count_other": "{count} メンバー",
         "delete_confirm_label": "確認のためにグループ名を入力してください:",
         "delete_confirm_mismatch": "確認のためにグループ名を正確に入力してください。",
-        "virtual_internal_name": "内部"
+        "virtual_internal_name": "内部",
+        "members_loading": "メンバーを読み込み中…",
+        "members_empty": "メンバーなし",
+        "virtual_internal_explanation": "このサーバー上のすべての内部ユーザー"
     },
     "myshares": {
         "copyLink": "リンクをコピー",
diff --git a/static/locales/ko.json b/static/locales/ko.json
index 345cbe13..e93ba416 100644
--- a/static/locales/ko.json
+++ b/static/locales/ko.json
@@ -867,7 +867,10 @@
         "member_count_other": "구성원 {count}명",
         "delete_confirm_label": "확인을 위해 그룹 이름을 입력하세요:",
         "delete_confirm_mismatch": "확인을 위해 그룹 이름을 정확히 입력하세요.",
-        "virtual_internal_name": "내부"
+        "virtual_internal_name": "내부",
+        "members_loading": "구성원 로딩 중…",
+        "members_empty": "구성원 없음",
+        "virtual_internal_explanation": "이 서버의 모든 내부 사용자"
     },
     "myshares": {
         "copyLink": "링크 복사",
diff --git a/static/locales/nl.json b/static/locales/nl.json
index 33f93ec1..4c54be74 100644
--- a/static/locales/nl.json
+++ b/static/locales/nl.json
@@ -867,7 +867,10 @@
         "member_count_other": "{count} leden",
         "delete_confirm_label": "Typ de groepsnaam ter bevestiging:",
         "delete_confirm_mismatch": "Typ de groepsnaam exact om te bevestigen.",
-        "virtual_internal_name": "Intern"
+        "virtual_internal_name": "Intern",
+        "members_loading": "Leden laden…",
+        "members_empty": "Geen leden",
+        "virtual_internal_explanation": "Iedere interne gebruiker op deze server"
     },
     "myshares": {
         "copyLink": "Link kopiëren",
diff --git a/static/locales/pl.json b/static/locales/pl.json
index e9fff114..3d83473c 100644
--- a/static/locales/pl.json
+++ b/static/locales/pl.json
@@ -867,7 +867,10 @@
         "member_count_other": "{count} członków",
         "delete_confirm_label": "Wpisz nazwę grupy, aby potwierdzić:",
         "delete_confirm_mismatch": "Wpisz nazwę grupy dokładnie, aby potwierdzić.",
-        "virtual_internal_name": "Wewnętrzni"
+        "virtual_internal_name": "Wewnętrzni",
+        "members_loading": "Ładowanie członków…",
+        "members_empty": "Brak członków",
+        "virtual_internal_explanation": "Każdy użytkownik wewnętrzny na tym serwerze"
     },
     "myshares": {
         "copyLink": "Skopiuj link",
diff --git a/static/locales/pt.json b/static/locales/pt.json
index 358ba879..a9a2fa56 100644
--- a/static/locales/pt.json
+++ b/static/locales/pt.json
@@ -867,7 +867,10 @@
         "member_count_other": "{count} membros",
         "delete_confirm_label": "Digite o nome do grupo para confirmar:",
         "delete_confirm_mismatch": "Digite o nome do grupo exatamente para confirmar.",
-        "virtual_internal_name": "Interno"
+        "virtual_internal_name": "Interno",
+        "members_loading": "A carregar membros…",
+        "members_empty": "Sem membros",
+        "virtual_internal_explanation": "Todos os utilizadores internos neste servidor"
     },
     "myshares": {
         "copyLink": "Copiar link",
diff --git a/static/locales/ru.json b/static/locales/ru.json
index c2b1cfec..4786d4f1 100644
--- a/static/locales/ru.json
+++ b/static/locales/ru.json
@@ -867,7 +867,10 @@
         "member_count_other": "{count} участников",
         "delete_confirm_label": "Введите имя группы для подтверждения:",
         "delete_confirm_mismatch": "Введите имя группы точно для подтверждения.",
-        "virtual_internal_name": "Внутренние"
+        "virtual_internal_name": "Внутренние",
+        "members_loading": "Загрузка участников…",
+        "members_empty": "Нет участников",
+        "virtual_internal_explanation": "Каждый внутренний пользователь на этом сервере"
     },
     "myshares": {
         "copyLink": "Копировать ссылку",
diff --git a/static/locales/zh-TW.json b/static/locales/zh-TW.json
index 5d98739c..495218cd 100644
--- a/static/locales/zh-TW.json
+++ b/static/locales/zh-TW.json
@@ -867,7 +867,10 @@
         "member_count_other": "{count} 個成員",
         "delete_confirm_label": "請輸入群組名稱以確認：",
         "delete_confirm_mismatch": "請準確輸入群組名稱以確認。",
-        "virtual_internal_name": "內部"
+        "virtual_internal_name": "內部",
+        "members_loading": "正在載入成員…",
+        "members_empty": "無成員",
+        "virtual_internal_explanation": "本伺服器上的所有內部使用者"
     },
     "myshares": {
         "copyLink": "複製連結",
diff --git a/static/locales/zh.json b/static/locales/zh.json
index 428ce842..3adf619b 100644
--- a/static/locales/zh.json
+++ b/static/locales/zh.json
@@ -867,7 +867,10 @@
         "member_count_other": "{count} 个成员",
         "delete_confirm_label": "请输入群组名称以确认：",
         "delete_confirm_mismatch": "请准确输入群组名称以确认。",
-        "virtual_internal_name": "内部"
+        "virtual_internal_name": "内部",
+        "members_loading": "正在加载成员…",
+        "members_empty": "无成员",
+        "virtual_internal_explanation": "本服务器上的所有内部用户"
     },
     "myshares": {
         "copyLink": "复制链接",
diff --git a/tests/api/dedup_blob_cleanup.hurl b/tests/api/dedup_blob_cleanup.hurl
index c2563c34..63849750 100644
--- a/tests/api/dedup_blob_cleanup.hurl
+++ b/tests/api/dedup_blob_cleanup.hurl
@@ -90,6 +90,12 @@ file1_id: jsonpath "$.id"
 [Asserts]
 jsonpath "$.name" == "dedup-test.jpg"
 jsonpath "$.folder_id" == {{test_folder_id}}
+# Cross-check that the server's view of the uploaded content matches
+# the BLAKE3 we computed locally over fixtures/dedup-test.jpg. The
+# `content_hash` field is the raw blob hash, distinct from `etag`
+# (which folds in modified_at) — exposed in REST JSON by the
+# etag-centralization refactor.
+jsonpath "$.content_hash" == "cde1ca663a2e62e0dadb41c3194e11ecb7d971d84c7451db17063b55c09e8066"
 
 
 # ref_count == 1: blob has exactly one file reference after first upload
@@ -118,6 +124,10 @@ file2_id: jsonpath "$.id"
 [Asserts]
 jsonpath "$.name" == "dedup-test-2.jpg"
 jsonpath "$.id" != "{{file1_id}}"
+# Same content as fixtures/dedup-test.jpg → identical content_hash.
+# This is the actual "dedup happened" assertion at the API surface,
+# independent of the /api/dedup/check probe below.
+jsonpath "$.content_hash" == "cde1ca663a2e62e0dadb41c3194e11ecb7d971d84c7451db17063b55c09e8066"
 
 
 # ref_count == 2: dedup hit — same blob now referenced by two file records
diff --git a/tests/webdav/test_chunked_upload_dedup.sh b/tests/webdav/test_chunked_upload_dedup.sh
index 51094cf1..c9cd10d7 100755
--- a/tests/webdav/test_chunked_upload_dedup.sh
+++ b/tests/webdav/test_chunked_upload_dedup.sh
@@ -146,6 +146,18 @@ MIME=$(jq -r '.mime_type' <<< "$LISTED_FILE")
     || fail "Expected MIME type video/mp4, got: $MIME"
 pass "File listed with MIME type: $MIME"
 
+# ── Step 4b: server's content_hash matches our local BLAKE3 ──────────────────
+# Cross-check the file we just uploaded: the server's view of its
+# content identity (FileDto.content_hash, exposed in REST JSON since
+# the etag-centralization refactor) must equal the BLAKE3 we know
+# the fixture has. Catches any chunk-assembly bug that would
+# silently produce a different blob than the source bytes.
+
+LISTED_HASH=$(jq -r '.content_hash // empty' <<< "$LISTED_FILE")
+[[ "$LISTED_HASH" == "$BLOB_HASH" ]] \
+    || fail "content_hash mismatch: server=$LISTED_HASH expected=$BLOB_HASH"
+pass "content_hash matches local BLAKE3 ($BLOB_HASH)"
+
 # ── Step 5: Dedup check → ref_count == 1 ─────────────────────────────────────
 
 echo "  step 5: GET /api/dedup/check/$BLOB_HASH..."
diff --git a/tests/webdav/test_dedup_webdav_multichunk.sh b/tests/webdav/test_dedup_webdav_multichunk.sh
index 967124a8..dd742afc 100755
--- a/tests/webdav/test_dedup_webdav_multichunk.sh
+++ b/tests/webdav/test_dedup_webdav_multichunk.sh
@@ -141,6 +141,22 @@ FILE_B_ID=$(jq -r --arg n "$FILE_B" '.[] | select(.name == $n) | .id' <<< "$LIST
     || fail "File A and B share the same ID — dedup must create two distinct records"
 pass "Two distinct file records: A=$FILE_A_ID  B=$FILE_B_ID"
 
+# ── Step 2b: server's content_hash matches our local BLAKE3 for both ─────────
+# Both files were uploaded from byte-identical bytes, so the server
+# MUST report the same content_hash for both — and that hash MUST
+# equal the BLAKE3 we computed locally. Without this check, a
+# subtle CDC-assembly bug could produce two distinct blobs that
+# happen to map to the same dedup key but differ from the source —
+# the ref_count assertions below would still pass.
+
+FILE_A_HASH=$(jq -r --arg n "$FILE_A" '.[] | select(.name == $n) | .content_hash // empty' <<< "$LISTING")
+FILE_B_HASH=$(jq -r --arg n "$FILE_B" '.[] | select(.name == $n) | .content_hash // empty' <<< "$LISTING")
+[[ "$FILE_A_HASH" == "$BLOB_HASH" ]] \
+    || fail "content_hash mismatch for A: server=$FILE_A_HASH expected=$BLOB_HASH"
+[[ "$FILE_B_HASH" == "$BLOB_HASH" ]] \
+    || fail "content_hash mismatch for B: server=$FILE_B_HASH expected=$BLOB_HASH"
+pass "content_hash on both A and B matches local BLAKE3 ($BLOB_HASH)"
+
 # ── Step 3: ref_count == 2 ────────────────────────────────────────────────────
 
 echo "  step 3: dedup/check → expect ref_count=2..."
diff --git a/tests/webdav/test_dedup_webdav_ref_count.sh b/tests/webdav/test_dedup_webdav_ref_count.sh
index 7a87762d..e1bf400a 100755
--- a/tests/webdav/test_dedup_webdav_ref_count.sh
+++ b/tests/webdav/test_dedup_webdav_ref_count.sh
@@ -147,6 +147,20 @@ FILE_B_ID=$(jq -r --arg n "$FILE_B" '.[] | select(.name == $n) | .id' <<< "$FILE
     || fail "File A and B share the same ID — dedup must produce two distinct records"
 pass "Two distinct file records: A=$FILE_A_ID  B=$FILE_B_ID"
 
+# ── Step 3b: server's content_hash matches our local BLAKE3 for both ─────────
+# Both files were uploaded from byte-identical content — server's
+# `content_hash` field (exposed via the etag-centralization refactor)
+# must equal BLOB_HASH for both, proving the server's view of
+# content identity agrees with our local computation.
+
+FILE_A_HASH=$(jq -r --arg n "$FILE_A" '.[] | select(.name == $n) | .content_hash // empty' <<< "$FILE_LISTING")
+FILE_B_HASH=$(jq -r --arg n "$FILE_B" '.[] | select(.name == $n) | .content_hash // empty' <<< "$FILE_LISTING")
+[[ "$FILE_A_HASH" == "$BLOB_HASH" ]] \
+    || fail "content_hash mismatch for A: server=$FILE_A_HASH expected=$BLOB_HASH"
+[[ "$FILE_B_HASH" == "$BLOB_HASH" ]] \
+    || fail "content_hash mismatch for B: server=$FILE_B_HASH expected=$BLOB_HASH"
+pass "content_hash on both A and B matches local BLAKE3 ($BLOB_HASH)"
+
 # ── Step 4: Dedup check → ref_count == 2 ─────────────────────────────────────
 
 echo "  step 4: GET /api/dedup/check/$BLOB_HASH..."
@@ -168,6 +182,25 @@ STATUS=$(webdav_put "$FILE_B" "$FIXTURE_OTHER" "image/jpeg")
 [[ "$STATUS" == "204" ]] || fail "PUT $FILE_B (overwrite) expected 204, got $STATUS"
 pass "PUT $FILE_B overwrite → 204"
 
+# ── Step 5b: B's content_hash flipped, A's unchanged ─────────────────────────
+# After overwrite, B references a new blob (oxicloud-logo.jpg)
+# whose BLAKE3 differs from BLOB_HASH; A still holds the original.
+# A weaker but local-fixture-agnostic check than asserting B's new
+# exact hash (avoids hardcoding a second BLAKE3) — proves that the
+# COW-overwrite path swaps the blob identity rather than silently
+# keeping the old one.
+
+REFRESHED=$(rest_get "/api/files?folder_id=$HOME_FOLDER_ID")
+FILE_A_HASH_AFTER=$(jq -r --arg n "$FILE_A" '.[] | select(.name == $n) | .content_hash // empty' <<< "$REFRESHED")
+FILE_B_HASH_AFTER=$(jq -r --arg n "$FILE_B" '.[] | select(.name == $n) | .content_hash // empty' <<< "$REFRESHED")
+[[ "$FILE_A_HASH_AFTER" == "$BLOB_HASH" ]] \
+    || fail "File A's content_hash changed unexpectedly: $FILE_A_HASH_AFTER (overwrite of B must not touch A)"
+[[ "$FILE_B_HASH_AFTER" != "$BLOB_HASH" ]] \
+    || fail "File B's content_hash unchanged after overwrite — COW path didn't swap the blob"
+[[ -n "$FILE_B_HASH_AFTER" ]] \
+    || fail "File B has empty content_hash after overwrite — server didn't compute a new blob"
+pass "post-overwrite: A still on $BLOB_HASH, B flipped to $FILE_B_HASH_AFTER"
+
 # ── Step 6: Dedup check → ref_count == 1 ─────────────────────────────────────
 # File B now references a different blob; file A still holds the original.