diff --git a/src/application/services/batch_operations.rs b/src/application/services/batch_operations.rs
index 921d88b4..2840b474 100644
--- a/src/application/services/batch_operations.rs
+++ b/src/application/services/batch_operations.rs
@@ -715,6 +715,11 @@ impl BatchOperationService {
         let buf_writer = BufWriter::with_capacity(256 * 1024, tokio_file);
         let mut zip = ZipFileWriter::with_tokio(buf_writer);
 
+        // Track whether any item was authorized + added to the ZIP. If
+        // none were, return NotFound — empty ZIPs are useless and mask
+        // authz failures from the client.
+        let mut items_added: usize = 0;
+
         // ── Add individual files at the root of the ZIP ──────────────────
         for file_id in &file_ids {
             match self
@@ -723,11 +728,14 @@ impl BatchOperationService {
                 .await
             {
                 Ok(file_dto) => {
-                    if let Err(e) = self
+                    match self
                         .add_file_entry_streamed(&mut zip, file_id, &file_dto.name, user_id)
                         .await
                     {
-                        info!("Could not add file {} to ZIP: {}", file_dto.name, e);
+                        Ok(_) => items_added += 1,
+                        Err(e) => {
+                            info!("Could not add file {} to ZIP: {}", file_dto.name, e);
+                        }
                     }
                 }
                 Err(e) => {
@@ -744,11 +752,14 @@ impl BatchOperationService {
                 .await
             {
                 Ok(root_folder) => {
-                    if let Err(e) = self
+                    match self
                         .add_folder_subtree_to_zip(&mut zip, folder_id, &root_folder, user_id)
                         .await
                     {
-                        info!("Could not add folder {} to ZIP: {}", root_folder.name, e);
+                        Ok(_) => items_added += 1,
+                        Err(e) => {
+                            info!("Could not add folder {} to ZIP: {}", root_folder.name, e);
+                        }
                     }
                 }
                 Err(e) => {
@@ -757,6 +768,14 @@ impl BatchOperationService {
             }
         }
 
+        // Bail out before finalizing the ZIP if nothing was authorized.
+        if items_added == 0 {
+            return Err(BatchOperationError::Domain(DomainError::not_found(
+                "BatchDownload",
+                "No accessible files or folders in the request",
+            )));
+        }
+
         // ── Finalize ─────────────────────────────────────────────────────
         let mut compat_writer = zip
             .close()
diff --git a/src/interfaces/api/handlers/batch_handler.rs b/src/interfaces/api/handlers/batch_handler.rs
index 8b650f0e..7ca55116 100644
--- a/src/interfaces/api/handlers/batch_handler.rs
+++ b/src/interfaces/api/handlers/batch_handler.rs
@@ -15,6 +15,7 @@ use crate::application::services::batch_operations::{
 };
 use crate::interfaces::api::deserializer;
 use crate::interfaces::api::handlers::ApiResult;
+use crate::interfaces::errors::AppError;
 use crate::interfaces::middleware::auth::AuthUser;
 
 /// Maximum number of items allowed in a single batch request.
@@ -1010,10 +1011,19 @@ async fn process_download_batch(
         .await
         .map_err(|e| {
             tracing::error!("Batch download ZIP failed: {}", e);
-            (
-                StatusCode::INTERNAL_SERVER_ERROR,
-                "Batch download failed".to_string(),
-            )
+            // Surface DomainError variants (NotFound when no items were
+            // authorized) with their natural HTTP status code instead of
+            // collapsing everything to 500.
+            match e {
+                crate::application::services::batch_operations::BatchOperationError::Domain(de) => {
+                    let app: AppError = de.into();
+                    (app.status_code, app.message)
+                }
+                other => (
+                    StatusCode::INTERNAL_SERVER_ERROR,
+                    format!("Batch download failed: {}", other),
+                ),
+            }
         })?;
 
     // Read file size for Content-Length before splitting ownership
diff --git a/tests/api/grants.hurl b/tests/api/grants.hurl
index adf09960..54e593e6 100644
--- a/tests/api/grants.hurl
+++ b/tests/api/grants.hurl
@@ -805,3 +805,429 @@ Authorization: Bearer {{adam_token}}
 HTTP 200
 [Asserts]
 jsonpath "$" count == 0
+
+
+# ════════════════════════════════════════════════════════════════════
+# PHASE 3 — Batch operations (/api/batch/*)
+# ════════════════════════════════════════════════════════════════════
+# Every batch endpoint passes caller_id through to the batch service,
+# which delegates per-item to engine-aware *_with_perms methods. The
+# handler aggregates results: 200 (all OK), 206 (mixed), 400 (all failed).
+#
+# Endpoints exercised:
+#   POST   /api/batch/files/get      · /api/batch/files/move
+#   POST   /api/batch/files/copy     · /api/batch/files/delete
+#   POST   /api/batch/folders/get    · /api/batch/folders/create
+#   POST   /api/batch/folders/move   · /api/batch/folders/copy
+#   POST   /api/batch/folders/delete · /api/batch/trash
+#   POST   /api/batch/download       · GET /api/batch/download (querystring)
+#
+# Fresh user "frank" — no grants from earlier phases.
+
+
+# ─────────────────────────────────────────────────────────────
+# Step P3.1 — Create frank and login.
+# ─────────────────────────────────────────────────────────────
+POST {{base_url}}/api/admin/users
+Authorization: Bearer {{alice_token}}
+Content-Type: application/json
+{ "username": "frank", "password": "FrankPassword1!", "email": "frank@example.com", "role": "user" }
+
+HTTP 201
+[Captures]
+frank_user_id: jsonpath "$.id"
+
+POST {{base_url}}/api/auth/login
+Content-Type: application/json
+{ "username": "frank", "password": "FrankPassword1!" }
+
+HTTP 200
+[Captures]
+frank_token: jsonpath "$.access_token"
+
+
+# ─────────────────────────────────────────────────────────────
+# Step P3.2 — Alice creates a batch-test folder with 2 sub-folders
+#             and 2 files (all owned by alice).
+# ─────────────────────────────────────────────────────────────
+POST {{base_url}}/api/folders
+Authorization: Bearer {{alice_token}}
+Content-Type: application/json
+{ "name": "batch-test", "parent_id": "{{alice_home_id}}" }
+
+HTTP 201
+[Captures]
+batch_root_id: jsonpath "$.id"
+
+POST {{base_url}}/api/folders
+Authorization: Bearer {{alice_token}}
+Content-Type: application/json
+{ "name": "batch-sub-A", "parent_id": "{{batch_root_id}}" }
+
+HTTP 201
+[Captures]
+batch_sub_a_id: jsonpath "$.id"
+
+POST {{base_url}}/api/folders
+Authorization: Bearer {{alice_token}}
+Content-Type: application/json
+{ "name": "batch-sub-B", "parent_id": "{{batch_root_id}}" }
+
+HTTP 201
+[Captures]
+batch_sub_b_id: jsonpath "$.id"
+
+POST {{base_url}}/api/files/upload
+Authorization: Bearer {{alice_token}}
+[MultipartFormData]
+folder_id: {{batch_root_id}}
+file: file,fixtures/red-image.png; image/png
+
+HTTP 201
+[Captures]
+batch_file_1_id: jsonpath "$.id"
+
+POST {{base_url}}/api/files/upload
+Authorization: Bearer {{alice_token}}
+[MultipartFormData]
+folder_id: {{batch_root_id}}
+file: file,fixtures/green-image.png; image/png
+
+HTTP 201
+[Captures]
+batch_file_2_id: jsonpath "$.id"
+
+
+# ════════════════════════════════════════════════════════════════════
+# Phase 3A — frank has NO grant. Every batch op returns 400 (all failed).
+# ════════════════════════════════════════════════════════════════════
+
+# Files — get
+POST {{base_url}}/api/batch/files/get
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_1_id}}", "{{batch_file_2_id}}"] }
+
+HTTP 400
+[Asserts]
+jsonpath "$.stats.successful" == 0
+jsonpath "$.stats.failed" == 2
+
+# Files — move
+POST {{base_url}}/api/batch/files/move
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_1_id}}"], "target_folder_id": "{{batch_sub_a_id}}" }
+
+HTTP 400
+[Asserts]
+jsonpath "$.stats.failed" == 1
+
+# Files — copy
+POST {{base_url}}/api/batch/files/copy
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_1_id}}"], "target_folder_id": "{{batch_sub_a_id}}" }
+
+HTTP 400
+[Asserts]
+jsonpath "$.stats.failed" == 1
+
+# Files — delete
+POST {{base_url}}/api/batch/files/delete
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_1_id}}"] }
+
+HTTP 400
+[Asserts]
+jsonpath "$.stats.failed" == 1
+
+# Folders — get
+POST {{base_url}}/api/batch/folders/get
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "folder_ids": ["{{batch_sub_a_id}}", "{{batch_sub_b_id}}"] }
+
+HTTP 400
+[Asserts]
+jsonpath "$.stats.failed" == 2
+
+# Folders — create child (no Create on batch_root)
+POST {{base_url}}/api/batch/folders/create
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "folders": [{ "name": "frank-attack", "parent_id": "{{batch_root_id}}" }] }
+
+HTTP 400
+
+# Folders — move
+POST {{base_url}}/api/batch/folders/move
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "folder_ids": ["{{batch_sub_a_id}}"], "target_folder_id": "{{batch_sub_b_id}}" }
+
+HTTP 400
+
+# Folders — copy
+POST {{base_url}}/api/batch/folders/copy
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "folder_ids": ["{{batch_sub_a_id}}"], "target_folder_id": "{{batch_sub_b_id}}" }
+
+HTTP 400
+
+# Folders — delete
+POST {{base_url}}/api/batch/folders/delete
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "folder_ids": ["{{batch_sub_a_id}}"], "recursive": false }
+
+HTTP 400
+
+# Trash (mixed)
+POST {{base_url}}/api/batch/trash
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_1_id}}"], "folder_ids": ["{{batch_sub_a_id}}"] }
+
+HTTP 400
+[Asserts]
+jsonpath "$.stats.failed" == 2
+
+# Download POST — engine rejects each item; batch service tracks
+# `items_added` and bails out with NotFound when none were authorized.
+POST {{base_url}}/api/batch/download
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_1_id}}"], "folder_ids": [] }
+
+HTTP 404
+
+# Download GET (querystring variant) — same behavior
+GET {{base_url}}/api/batch/download?file_ids={{batch_file_1_id}}
+Authorization: Bearer {{frank_token}}
+
+HTTP 404
+
+
+# ════════════════════════════════════════════════════════════════════
+# Phase 3B — Alice grants frank Viewer. Read endpoints succeed;
+#            mutating batch ops still all-fail.
+# ════════════════════════════════════════════════════════════════════
+POST {{base_url}}/api/grants
+Authorization: Bearer {{alice_token}}
+Content-Type: application/json
+{
+  "subject":  { "type": "user",   "id": "{{frank_user_id}}" },
+  "resource": { "type": "folder", "id": "{{batch_root_id}}" },
+  "role": "viewer"
+}
+
+HTTP 201
+
+# get_files succeeds (Read cascades to all descendants)
+POST {{base_url}}/api/batch/files/get
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_1_id}}", "{{batch_file_2_id}}"] }
+
+HTTP 200
+[Asserts]
+jsonpath "$.stats.successful" == 2
+jsonpath "$.stats.failed" == 0
+
+# get_folders succeeds
+POST {{base_url}}/api/batch/folders/get
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "folder_ids": ["{{batch_sub_a_id}}", "{{batch_sub_b_id}}"] }
+
+HTTP 200
+[Asserts]
+jsonpath "$.stats.successful" == 2
+
+# Download POST as Viewer — succeeds (Read sufficient)
+POST {{base_url}}/api/batch/download
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_1_id}}", "{{batch_file_2_id}}"], "folder_ids": [] }
+
+HTTP 200
+[Asserts]
+header "Content-Type" == "application/zip"
+
+# Download GET — same
+GET {{base_url}}/api/batch/download?file_ids={{batch_file_1_id}},{{batch_file_2_id}}
+Authorization: Bearer {{frank_token}}
+
+HTTP 200
+[Asserts]
+header "Content-Type" == "application/zip"
+
+# Mutations still rejected
+POST {{base_url}}/api/batch/files/move
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_1_id}}"], "target_folder_id": "{{batch_sub_a_id}}" }
+
+HTTP 400
+
+POST {{base_url}}/api/batch/files/delete
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_1_id}}"] }
+
+HTTP 400
+
+
+# ════════════════════════════════════════════════════════════════════
+# Phase 3C — Promote frank to Editor (read + comment + create + update).
+#            Move + copy + create succeed; delete still fails.
+# ════════════════════════════════════════════════════════════════════
+PUT {{base_url}}/api/grants/role
+Authorization: Bearer {{alice_token}}
+Content-Type: application/json
+{
+  "subject":  { "type": "user",   "id": "{{frank_user_id}}" },
+  "resource": { "type": "folder", "id": "{{batch_root_id}}" },
+  "role": "editor"
+}
+
+HTTP 200
+
+# Batch folder create (Create on parent)
+POST {{base_url}}/api/batch/folders/create
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{
+  "folders": [
+    { "name": "frank-batch-1", "parent_id": "{{batch_root_id}}" },
+    { "name": "frank-batch-2", "parent_id": "{{batch_root_id}}" }
+  ]
+}
+
+HTTP 201
+[Asserts]
+jsonpath "$.stats.successful" == 2
+
+# Batch file move (Update on file + Create on target)
+POST {{base_url}}/api/batch/files/move
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_1_id}}"], "target_folder_id": "{{batch_sub_a_id}}" }
+
+HTTP 200
+[Asserts]
+jsonpath "$.stats.successful" == 1
+
+# Batch file copy (Read on src + Create on dst)
+POST {{base_url}}/api/batch/files/copy
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_2_id}}"], "target_folder_id": "{{batch_sub_b_id}}" }
+
+HTTP 200
+[Asserts]
+jsonpath "$.stats.successful" == 1
+
+# Batch folder move
+POST {{base_url}}/api/batch/folders/move
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "folder_ids": ["{{batch_sub_a_id}}"], "target_folder_id": "{{batch_sub_b_id}}" }
+
+HTTP 200
+
+# Batch folder copy — copy sub_a (now nested inside sub_b after the
+# move above) back to batch_root. Avoids name collision with the
+# existing sub_b at the root.
+POST {{base_url}}/api/batch/folders/copy
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "folder_ids": ["{{batch_sub_a_id}}"], "target_folder_id": "{{batch_root_id}}" }
+
+HTTP 200
+
+# Batch delete still denied (Editor excludes Delete)
+POST {{base_url}}/api/batch/files/delete
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_2_id}}"] }
+
+HTTP 400
+
+POST {{base_url}}/api/batch/folders/delete
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "folder_ids": ["{{batch_sub_b_id}}"], "recursive": true }
+
+HTTP 400
+
+
+# ════════════════════════════════════════════════════════════════════
+# Phase 3D — Promote frank to Admin. Delete + trash succeed.
+# ════════════════════════════════════════════════════════════════════
+PUT {{base_url}}/api/grants/role
+Authorization: Bearer {{alice_token}}
+Content-Type: application/json
+{
+  "subject":  { "type": "user",   "id": "{{frank_user_id}}" },
+  "resource": { "type": "folder", "id": "{{batch_root_id}}" },
+  "role": "admin"
+}
+
+HTTP 200
+
+# Batch trash — CURRENT LIMITATION: even with Admin (Delete grant via
+# engine), the trash flow inside trash_service uses get_file_for_owner
+# at the data layer, which is owner-scoped. So a non-owner with Delete
+# grant gets engine-OK but the SQL filter blocks the fetch → 400.
+# This is documented inconsistency; a follow-up should make trash use
+# the engine for its lookup too. For now: only the owner can trash.
+POST {{base_url}}/api/batch/trash
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_2_id}}"], "folder_ids": [] }
+
+HTTP 400
+
+# Alice (owner) CAN batch-trash — keeps coverage of the success path.
+POST {{base_url}}/api/batch/trash
+Authorization: Bearer {{alice_token}}
+Content-Type: application/json
+{ "file_ids": ["{{batch_file_2_id}}"], "folder_ids": [] }
+
+HTTP 200
+[Asserts]
+jsonpath "$.stats.successful" == 1
+
+# Batch permanent-delete a folder
+POST {{base_url}}/api/batch/folders/delete
+Authorization: Bearer {{frank_token}}
+Content-Type: application/json
+{ "folder_ids": ["{{batch_sub_b_id}}"], "recursive": true }
+
+HTTP 200
+
+
+# ════════════════════════════════════════════════════════════════════
+# Phase 3E — Lifecycle cleanup. Alice deletes the batch-test root.
+#            Trigger removes all of frank's grants.
+# ════════════════════════════════════════════════════════════════════
+DELETE {{base_url}}/api/folders/{{batch_root_id}}
+Authorization: Bearer {{alice_token}}
+
+HTTP 204
+
+DELETE {{base_url}}/api/trash/empty
+Authorization: Bearer {{alice_token}}
+
+HTTP 200
+
+GET {{base_url}}/api/grants/incoming
+Authorization: Bearer {{frank_token}}
+
+HTTP 200
+[Asserts]
+jsonpath "$" count == 0