Oxicloud/docs/plan/drive.md

Drives — design proposal

Status: design proposal, locked but not implemented. Reviewed Jun 2026 with Ed; all blocking decisions answered. Open items listed at the end of the file.

Context

Today every resource (folder, file) in OxiCloud has a single user owner recorded directly on the row (storage.folders.user_id, storage.files.user_id). Sharing is layered on top via ReBAC grants in storage.access_grants. The model is simple and has carried us this far, but it has two structural problems:

1. Owner = user, full stop. When a user leaves the company, their files leave with them. The team's de-facto shared folders are technically owned by a single person; transferring ownership requires moving every resource one-by-one and re-issuing every grant. There is no "this folder belongs to the Engineering team" concept.

2. Quota is per-user, full stop. A user with personal storage who also collaborates in a 1 TB team space currently has both counted against their personal quota (or the team data costs are absorbed by whoever owns the folder). There is no way to bill team storage to the team.

The proposal is to introduce drives as a Google-Workspace-style container concept:

• Every resource belongs to exactly one drive.
• A drive has owners (users and/or groups) with roles.
• Each user automatically gets a personal drive at registration.
• Shared drives can be owned by groups, so membership changes automatically follow the group — "Bob left" no longer needs an admin to chase down which folders to reassign.
• Quotas move from users to drives.
• Per-drive policies enable team-level rules (forbid public links, forbid sharing, forbid cross-drive moves, future: timeboxed sessions, end-to-end encryption).

The shift is large but the model is well-understood — it's the same pattern Google Workspace's Shared Drives and Microsoft SharePoint Document Libraries use. OxiCloud users coming from those services will recognise it instantly.

Prerequisite — PR D-Prep: access_grants → role_grants

Status (2026-06-17): scope complete, ready to PR. The schema migration runs cleanly against real sandbox data (38 role_grants rows produced, matching the audit's 29 viewer / 5 editor / 4 owner distribution, zero bundle mismatches). End-to-end Hurl test (tests/api/role_grants.hurl) covers create / atomic role update / revoke with both the canonical "owner" and the legacy "admin" compat wire format. Engine reads pivot to role_grants for authz decisions; access_grants stays populated via dual-write as the safety net for one release cycle. Ratified 2026-06-16. A separate PR lands BEFORE D0 that refactors storage.access_grants into storage.role_grants with role-bundle semantics:

storage.role_grants
    id            uuid PRIMARY KEY DEFAULT gen_random_uuid()
    subject_type  text NOT NULL CHECK (subject_type IN ('user','group'))
    subject_id    uuid NOT NULL
    resource_type text NOT NULL  -- 'folder','file','drive','group',…
    resource_id   uuid NOT NULL
    role          text NOT NULL CHECK (role IN ('viewer','editor','owner', …))
    expires_at    timestamptz NULL
    granted_by    uuid NOT NULL FK → auth.users(id)
    granted_at    timestamptz NOT NULL DEFAULT now()

Roles map to permission bundles via a single server-side function role_bundle(role) -> &[Permission]:

Role	Bundle
viewer	Read
editor	Read, Create, Update, Comment
owner	Read, Create, Update, Comment, Delete, Share, Manage

Manage is a new Permission introduced in this refactor — covers "configure this resource's settings, add/remove members, change role assignments". Future-friendly for Group-as-Resource.

Why first:

1. Refactor has standalone value beyond Drive (cleaner API, audit log, UI surface).
2. Doing it AFTER Drive would force migrating both access_grants AND drive_members — solving the unification first means D0 migrates one table, not two.
3. The drive_members table planned by earlier drafts goes away. Drive membership becomes rows in role_grants with resource_type='drive'. One table, one engine, one cache.

The sections below describe the Drive model assuming D-Prep has landed. References to "drive membership" mean rows in role_grants with resource_type='drive', not a separate table.

Gating policy: D-Prep must ship, bake in production, and pass validation across the API surface (grant endpoints, audit log events) and the UI surface (My Shares dialog, share modals, admin group/role views) before any of the Drive PRs (D0–D7) begin. The goal is to surface and absorb refactor-related issues against the existing single-resource model — not to discover them mid-flight while the Drive migration is also in motion. If D-Prep needs follow-up patches after deploy, they land as standalone fixes before D0 starts.

Locked design (decisions ratified in design discussion)

1. Ownership pivot

• A new table storage.drives becomes the ownership anchor.
• storage.folders and storage.files lose their user_id column; they gain drive_id NOT NULL.
• The owner of a resource is computed via resource.drive_id → drive.drive_members WHERE role='owner' — a JOIN, not a denormalised column. The drives table will be tiny (one row per internal user + handful of shared drives), so the join is cheap with a proper index.
• Single source of truth confirmed. user_id is dropped from resources after a migration phase (see Migration below).

2. Drive membership

Drive membership lives in storage.role_grants (introduced by PR D-Prep — see prerequisite above) with resource_type='drive' and resource_id=<drive uuid>. There is no separate drive_members table. One row per (subject, drive) pair carries the role; the role expands to a permission bundle via the same role_bundle() function used everywhere else.

Concretely, a drive membership is:

INSERT INTO storage.role_grants
       (subject_type, subject_id, resource_type, resource_id, role, granted_by)
VALUES ('user',       $user_id,   'drive',       $drive_id,   'editor', $admin_id);

The PgAclEngine reads this row no differently than any other grant; the drive-membership concept exists only at the application layer (DriveService enforces the personal-drive invariants, etc.) — there's no separate engine path or cache keyspace.

• A shared drive (kind='shared') can have 0..N user owners + 0..N group owners (mixed freely) plus any number of editors/viewers.
• A personal drive (kind='personal') has exactly one member row in drive_members, fixed to (subject_type='user', subject_id=<the user>, role='owner'). The rule applies to every kind='personal' row, whether it carries default_for_user IS NOT NULL (the user's default drive) or default_for_user IS NULL (a secondary personal silo, e.g. a SQL-created sibling root folder promoted by migration §10). Secondary does not loosen the single-user constraint.
  • Personal drives cannot be added to, role-changed, or have their sole owner removed. They cannot be co-owned. They cannot be transferred to another user. This matches Google Drive's "My Drive" and Microsoft's "OneDrive" semantics: a personal drive is a single-user namespace; collaboration happens through per-resource grants, by moving content into a shared drive, or by promoting a secondary personal drive to kind='shared' (capability matrix in §3).
  • Enforcement is at the application layer: DriveService::add_member refuses when kind='personal'; remove_member refuses when the drive is personal. User deletion cleans up the user's default personal drive via the default_for_user FK cascade, and the user's secondary personal drives via an application-layer pass (those have no FK to cascade through — see §6 lifecycle).
• Shared-drive last-owner protection: removing the final role='owner' member of a shared drive is refused at the application layer. The check counts remaining owner-role members (expanding group owners to their members) and rejects the delete if the count would become zero.
• A shared drive can have 0 viewers and 0 editors — only the ≥1-owner invariant matters.

3. Drive entity

storage.drives
    id                uuid PRIMARY KEY DEFAULT gen_random_uuid()
    name              text NOT NULL                       -- "Personal" or user-chosen
    kind              text NOT NULL CHECK (kind IN ('personal','shared'))
    default_for_user  uuid NULL FK → auth.users(id) ON DELETE CASCADE
    quota_bytes       bigint NULL                         -- NULL = unlimited
    used_bytes        bigint NOT NULL DEFAULT 0
    policies          jsonb NOT NULL DEFAULT '{}'
    created_at        timestamptz NOT NULL DEFAULT now()
    updated_at        timestamptz NOT NULL DEFAULT now()
    -- `default_for_user` may ONLY be set on personal drives.
    -- Shared drives have it NULL by definition.
    CONSTRAINT drives_default_marker_personal_only
        CHECK (default_for_user IS NULL OR kind = 'personal')

CREATE UNIQUE INDEX drives_default_for_user_idx
    ON storage.drives (default_for_user)
    WHERE default_for_user IS NOT NULL;  -- one DEFAULT personal drive per user

Two orthogonal properties: kind and default_for_user

• kind = drive capability shape (see §2 for the rules):
  • 'personal' = single-user single-owner; cannot have members added; sharing happens only through per-resource grants.
  • 'shared' = multi-owner / multi-member; supports user and group members at every role.
• default_for_user = "this is the default drive for user X". Set on exactly one kind='personal' drive per user (the partial unique index enforces it). Used by:
  • UI default-drive redirect (/ → /drive/<default>).
  • NC default-drive resolution when the credential doesn't pin a specific drive.
  • The ON DELETE CASCADE on this column cleans up the user's default drive in one step when the user is deleted.
  • Canonical lookup: SELECT id FROM storage.drives WHERE default_for_user = $1 — single-row, index-backed.

A user can have multiple kind='personal' drives — at most one of them carries default_for_user, the others sit as "secondary personal" silos (e.g. SQL-created root folders promoted by migration §10). Secondary personals follow the same single-owner rules as the default; they just aren't the default landing target.

External users never get a personal drive (lifecycle §6). There is no constraint to write — externals simply have no row in storage.drives with default_for_user = <their id>, and nothing tries to create one.

Drive naming — name is a label, identity lives in kind + default_for_user

name is owner-editable for every drive (personal or shared). A user who renames their drive from "Personal" → "Ed's space" does not stop having a personal drive, and does not stop having a default. The kind flag + default_for_user pointer carry the identity; the name is purely a display label.

Why this matters:

• UI and NC default-drive resolution MUST query on kind / default_for_user, never on name = 'Personal'. The latter would silently break the moment the user renames.
• The initial migration sets name = 'Personal' on the default personal drive for back-compat with the label users see today; further renames go through the normal drive-rename endpoint and persist on the same row. Secondary personal drives carry whatever name the sibling root folder had (e.g. Archive, 2024 Projects).

Capabilities matrix

Capability	kind='personal', default (default_for_user set)	kind='personal', secondary (default_for_user IS NULL)	kind='shared'
Membership shape	exactly 1 user-owner row	exactly 1 user-owner row	0..N users + 0..N groups at any role
add_member	refused	refused	allowed
remove_member	refused (sole owner is fixed)	refused (sole owner is fixed)	allowed except sole owner
Rename	allowed (by the owner)	allowed (by the owner)	allowed (by any owner)
Delete via API	refused — deleting this loses all the user's files; the only path is user-delete cascade	allowed (it's just a silo)	allowed (by an owner; CASCADEs the drive's contents)
Default-drive lookup result	this drive	never	never
On user-delete	ON DELETE CASCADE via default_for_user FK (free)	application-layer cleanup: enumerate via drive_members and delete	member rows referencing the user are dropped; refuse user-delete if any shared drive would lose its last owner
Group ownership	no	no	yes
Per-resource grant outward	yes (subject to drive policies)	yes	yes
Cross-drive move	yes (subject to forbid_cross_drive_move)	yes	yes
Kind conversion	no — always default-personal	yes → may be promoted to kind='shared' later (drops the single-user restriction, picks up members)	no

4. Roles → permission bundles

Drive-level roles map to existing ReBAC Permission values via union expansion:

Role	Permissions implied on every resource inside the drive
viewer	Read
editor	Read, Create, Update, Comment
owner	Read, Create, Update, Comment, Delete, Share, and drive-level admin (rename, edit policies, manage members, change quota)

5. Permission resolution — additive over role_grants

A user has permission P on resource R if any of the role_grants rows reachable from them (directly, via group membership, or via drive membership) carries a role whose bundle includes P. Specifically:

• A direct grant: (subject_type='user', subject_id=$user, resource_id=$R, role=…)
• A group-mediated grant: any role_grants row whose subject_type='group' points at a group the user is a transitive member of.
• A drive-mediated grant: any role_grants row whose resource_type='drive' and resource_id=$R.drive_id, with the same per-row role bundle.

Permissions are additive. Drive role is the baseline floor for every resource in the drive; explicit per-resource grants only add on top. There is no "revoke for this file even though you're a drive editor" concept, matching Google Workspace.

The auth engine reads role_grants as a single source of truth. Cache invalidation has one keyspace (rows in role_grants) instead of two. The drive-membership lookup ("what drives can this caller read?") is a WHERE subject_id=$1 AND resource_type='drive' scan against the same table.

6. Lifecycle rules

Event	Behaviour
New internal user registers	Auto-create a default personal drive (kind='personal', name='Personal', default_for_user=<new_user>, quota_bytes=<OXICLOUD_DEFAULT_QUOTA_BYTES>), insert the single drive_members (drive_id, user, <user_id>, owner) row.
External user invited (magic-link only)	No personal drive created. External users are grant-only recipients with no storage.
External user converts to internal (future flow)	Default personal drive created at conversion time.
User deleted	Default personal drive cascade-deletes via ON DELETE CASCADE on default_for_user. Secondary personal drives (kind='personal' AND default_for_user IS NULL and whose sole drive_members row points at the user) are deleted by an application-layer pass in the same transaction. Member rows referencing the deleted user are removed from all shared drives. If a removal would leave a shared drive with zero owners, deletion is refused — admin must transfer first.
Group deleted	Refuse if the group is a member of any shared drive that would lose its last owner. Admin must transfer or remove the group's role from those drives first. (Groups can't be members of personal drives.)
Add member to personal drive	Refuse. Personal drives are single-user — collaborate via per-resource grants or by moving content into a shared drive.
Remove sole owner of personal drive	Refuse. The only deletion path for a personal drive is user-deletion via cascade.
Delete personal drive	Refuse from the API. Only ON DELETE CASCADE (user deletion) drops it.
Rename personal or shared drive	Allowed for any owner-role caller. name is a label only.
Remove last owner of shared drive	Refuse — drive must always have ≥1 owner. App-layer check on DELETE FROM drive_members.

7. Quota model

The per-user auth.users.storage_quota_bytes field is migrated to the user's personal drive's quota_bytes in one step, then the column is deprecated (kept for one release cycle as a no-op, dropped in a later migration).

After the cutover:

• Every drive owns its quota. Files inside a drive count against that drive's used_bytes only.
• A user who collaborates in a 1 TB shared drive sees their personal drive's quota as "their" quota; the shared drive's quota is owned by the team.
• New drives default to a tenant-configured OXICLOUD_DEFAULT_DRIVE_QUOTA_BYTES setting (separate env var, replacing today's per-user equivalent).

used_bytes is maintained incrementally on every file insert/delete (plus a periodic reconciliation job to fix drift, similar to the existing per-user accounting).

Chunk dedup vs per-drive quota. With the CDC chunk store landed in v0.7.0 (see delta_upload_service, upload_ingest, instant upload by hash), a single chunk can be referenced by files in multiple drives. The accounting decision: each drive counts the file's logical size in full against its own used_bytes — dedup savings are server-side only and never visible in the per-drive quota number. This matches the existing per-user blob-dedup model and avoids the alternative "pro-rated quota" trap (which makes quota math depend on cross-drive content and breaks the user's mental model of "I have 1 TB free"). Reconciliation job sums file sizes per drive, not chunk allocations.

8. Policies (JSONB, extensible)

Each drive carries a policies JSON object. Five known keys for v1:

{
    "forbid_sharing":           false,  // disables per-resource grants on this drive
    "forbid_external_sharing":  false,  // blocks grants to is_external=true subjects
    "forbid_public_links":      false,  // blocks token-share (anonymous link) creation
    "forbid_cross_drive_move":  false   // blocks MOVE when src.drive_id != dst.drive_id
}

Enforcement points (one place per policy — single grep target):

Policy	Enforcement callsite
forbid_sharing	grant_handler::create_grant — checks resource.drive_id's policy before insertion
forbid_external_sharing	magic_link_invite_service::resolve_or_create_recipient and grant_handler::create_grant (when subject is is_external=true)
forbid_public_links	share_handler::create_shared_link
forbid_cross_drive_move	file_handler::move_file and folder_handler::move_folder — refuse when src.drive_id != dst.drive_id

Default to false (everything allowed) — opt-in by drive owner via the drive settings UI.

Policy semantics — subtleties to remember

• forbid_sharing disables per-resource grants on resources in the drive. Drive owners can still add drive-level members (otherwise the drive becomes uneditable except by the original owner). The policy means "no fine-grained sharing of individual files; access happens through drive membership only".
• forbid_cross_drive_move protects against exfiltration via UI move. It does not stop download + re-upload (that's a different category of policy — file-egress, future). UI surface should make this explicit so users don't read it as data-leak protection.

Future policy keys (out of scope for v1 — but the JSONB shape

accommodates them without schema migration)

• timeboxed_session — drive contents require re-auth after N minutes. Significant UX/middleware lift; defer.
• end_to_end_encrypted — client-side encryption; massive scope.

9. URL surface

Frontend

URL	Resolves to
/	Redirect to the caller's personal drive UUID
/drive/<drive-uuid>	Drive root view
/drive/<drive-uuid>/<folder-id>	Folder inside the drive

Native WebDAV (/webdav/...)

URL	Resolves to
/webdav/<path>	Caller's personal drive root + <path> (back-compat with today's behaviour)
/webdav/drives/<drive-uuid>/<path>	Specific drive root + <path>

Today's /webdav/<path> handler implicitly looks up the caller's home folder and prepends it. Post-drives, the same handler looks up the caller's personal drive and resolves paths inside it. Zero breakage for existing native WebDAV clients.

The drives path segment is reserved: a folder literally named drives cannot exist at the top level of any drive. Migration pre-check refuses to start if existing data violates this — operator must rename before upgrading. (Conservative estimate: zero existing folders are named exactly drives. The migration script reports any collisions for manual fix-up.)

NextCloud-compat WebDAV (/remote.php/dav/...)

The path-segment /drives/<uuid>/ form is NOT used on the NC surface. It is reserved for the native WebDAV surface (see table above). The NC surface keeps the URL shape /remote.php/dav/files/<username>/<path> and carries the drive selector in the credential, not the URL.

NC desktop / mobile clients store credentials per (host, username) and offer a single sync root per saved account. A path-segment scheme would require NC clients to grow multi-root awareness, which they don't have. Two credential-side mechanisms are valid here:

1. Username discriminator ({user}~{drive-uuid}) — the chroot POC on feat/nextcloud-drive (commit 137169b7). The Basic Auth username carries the drive UUID after a ~ separator; the URL stays under /remote.php/dav/files/{user}~{uuid}/<path>. Explicit on the wire, no per-credential server state needed beyond the existing app-password row.

2. App-password ↔ drive binding — store the chosen drive UUID directly on the auth.app_passwords row at issuance time. The Basic Auth username stays as {user} (clean NextCloud UX, no ~ to explain). The auth middleware looks up the app-password row, reads its drive_id binding, and uses that as the drive context. Each drive a user wants to sync gets its own app-password.

Both are workable; option (2) is the cleaner UX (username matches what users type, no extra character to explain) but requires a schema add on auth.app_passwords and one extra JOIN in the hot auth path. Option (1) is the smallest possible change but exposes the ~ to the user. They're not mutually exclusive — the issuance flow can produce credentials in either shape. Decide before D1 ships which is the default the Login Flow v2 picker produces.

URL	Resolves to
/remote.php/dav/files/<username>/<path>	That user's personal drive — unchanged. (App-password drive-binding NULL ⇒ personal.)
/remote.php/dav/files/<username>~<drive-uuid>/<path>	Option 1: explicit drive in the URL.
/remote.php/dav/files/<username>/<path> (with auth.app_passwords.drive_id set)	Option 2: drive resolved from the credential row. URL is indistinguishable from the unchanged personal case to the client.

In either case, the auth middleware asserts the caller is a member of the resolved drive before serving any DAV verb. Pre-existing NC clients pointed at /remote.php/dav/files/<username>/ continue syncing the user's personal drive without reconfiguration — regardless of which option is chosen as the default.

Username/UUID collision — defused

The /remote.php/dav/files/<x>/ vs /remote.php/dav/drives/<x>/ split solves the worry about username/UUID ambiguity. The discriminator is the literal segment (files vs drives), never the value of <x>. A user happening to have a UUID-shaped username is no longer a problem.

10. Storage paths — wrapper folder retired

Today storage.folders.path is e.g. My Folder - admin/Docs. The "My Folder - admin" wrapper is the user's home folder, created at registration via format!("My Folder - {}", username).

Post-drives, the wrapper goes away. The drive itself is the root; folders and files that used to live inside the wrapper sit directly under the drive with no intermediate folder:

Drive "Personal" (uuid=…, kind=personal, owner=admin) ← was the "My Folder - admin" wrapper
├── Docs/
└── aa.pdf

Same for shared drives — they already had no wrapper:

Drive "Engineering" (uuid=…, kind=shared, owners=group:engineering)
├── Specs/
├── Roadmap.md
└── archive/

The two surfaces share one rule: drive root = parent_id IS NULL within the drive's drive_id. The "personal vs shared" branch disappears from path resolution — both kinds resolve the same way.

Why this is client-safe

The wrapper was already invisible to WebDAV / NC clients pre-drive:

• NC clients hit /remote.php/dav/files/<user>/<path> and nc_to_internal_path prepended My Folder - <user>/ internally before talking to the storage layer. The client never saw the wrapper segment in its URL.
• Native /webdav/<path> was implicitly chrooted to the user's home by resolve_webdav_path. Same story.

So URL-level back-compat is preserved trivially — clients keep asking for /remote.php/dav/files/admin/Docs/foo.pdf, the resolver no longer prepends the wrapper, and the storage row's path is now Docs/foo.pdf instead of My Folder - admin/Docs/foo.pdf. Net effect on the wire: zero.

Why this is a better model

The original plan kept the wrapper "for back-compat" but it has no value beyond the storage layer (clients never see it, the filesystem mirror is happy either way). Keeping it forced path resolution to always know whether the caller is in a personal or shared drive and conditionally prepend a segment. Dropping it collapses that branch and makes the personal-vs-shared distinction purely a metadata concern (kind, quota source, member shape) — not a path-shape concern.

Sibling root folders also become drives

Today the only way to get a parent_id IS NULL folder is via the home-folder creation path, which produces exactly one per user. However, manual SQL has already been used (and may still be used by ops) to create additional top-level folders — folders that sit beside My Folder - <user> at parent_id IS NULL. These are not addressable today through any handler (the UI assumes exactly one root); they exist as data only.

Post-migration, the model has to absorb them. Rule:

• For each user, find every row with parent_id IS NULL AND user_id = <this user>.
• The one named My Folder - <username> becomes the default personal drive: kind='personal', default_for_user=<user>, sole member = the user.
• Every other sibling becomes a fresh secondary personal drive: kind='personal', default_for_user=NULL, sole member = the user, name carried over from the folder's name column, quota initialised from the user's quota (auth.users.storage_quota_bytes) — same default as the user's primary personal drive. Membership rules from §2 apply: the user cannot invite co-owners while the drive remains personal. To open the silo up, the user can later convert the secondary personal to kind='shared' (an application-layer operation that flips the kind and lifts the single-user restriction so the membership API can add other users / groups).
• The folder row is deleted (the drive replaces it as the root). Its children get their parent_id set to NULL within their new drive_id.

The chroot POC's "pick a drive at login" picker on feat/nextcloud-drive already produces the right shape for this: users with one drive auto-select Personal silently, users with N drives get a real picker. No POC change needed — it just sees real drive rows instead of folder UUIDs.

11. Content search index — drive-aware filtering

v0.7.0 added an embedded Tantivy full-text content index (see infrastructure/services/search_index/tantivy_content_index.rs and migration 20260701000000_content_search_index.sql). Today every indexed document carries the owning user as a filter field and queries restrict by that field at query time.

When ownership pivots to drive_id, the index has to follow — otherwise search leaks content across drives the moment D7 drops user_id:

1. Schema update: every indexed document gains a drive_id field stamped at ingest time. Existing documents need a one-shot reindex pass during the D0 migration (read each row, look up its new drive_id, update the index entry). Cheap on small instances; the migration script should report a progress count for larger ones.
2. Query path: instead of filtering by user_id = caller, expand caller → set of drive_ids the caller can read (personal + every shared-drive membership) and filter by drive_id ∈ that set. Expansion reuses the drive-role check already required by PgAclEngine.
3. Treat as a blocking step of D0, not a D4/D5-era polish item — otherwise the index is the silent leak path during the dual-write window.

Filtering on a low-cardinality drive_id is something Tantivy handles natively; this is bookkeeping, not a query-plan risk.

12. Trash — per-drive scoped, owner-actioned

Today trash is per-user: storage.files / storage.folders carry is_trashed BOOLEAN + trashed_at + original_parent_id (soft-delete in place), and storage.trash_items is a VIEW that UNIONs them. The listing endpoint (GET /api/trash/resources) filters by user_id = caller.

Post-drives, trash becomes per-drive:

• Storage shape is unchanged. The drive_id column added to storage.files / storage.folders in Phase A already identifies which drive a trashed row belongs to. No new trash table, no schema work beyond updating the storage.trash_items VIEW to surface drive_id alongside (or replacing) user_id.
• Trash listing query filters by drive(s) the caller can read. Default listing returns trash from every drive the caller has membership on; a ?drive_id=<uuid> parameter scopes to one drive. UI shows a drive picker above the trash list, same as the main file view.
• Trash mutations are owner-only. Per the §4 role-bundle, Delete is in the owner bundle only — so today's "anyone who can delete the original can act on its trash entry" is already drive-owner-scoped. Specifically:
  • Send to trash — any drive owner (carries Delete). Personal drive: the user themselves.
  • Restore — any drive owner. Operation reverses is_trashed, sets parent_id back to original_parent_id when that ancestor is still in the same drive (otherwise to the drive root with a name conflict resolver).
  • Permanent delete — any drive owner. Clears the row and decrements drive used_bytes.
  • View trash — any drive member (viewer / editor / owner). Viewers can see what was deleted from a drive they have access to; only owners can act on it. Mirrors Google Drive's per-shared-drive trash UX.
• Cross-drive moves carry their trash home with them: when a file moves from drive A → drive B and is later trashed, the row's drive_id is B's, so trash for B sees it (not A's, which is the natural and expected answer).
• Cascade on drive deletion: when a shared drive is deleted (D3 will land the delete-drive flow), every storage.files / storage.folders row with that drive_id cascades, trashed or not. There's no need to "drain the trash first" — the whole drive disappears in one CASCADE.
• Personal-drive trash follows the same model: bound to the personal drive, sole owner (= the user) does everything. No new UX divergence between personal and shared.

The orphan/aborted-upload sweep introduced in v0.7.0 (944c8337, periodic trash job) must become drive-aware so it doesn't accidentally sweep across drives the caller shouldn't see. It already keys off ownership; the rewrite is a per-drive pass instead of per-user.

13. Upload paths and quota timing

Four upload protocols, each with different "when do we know the size" and "when do we know the destination" answers. The Drive migration pivots quota from user-scoped to drive-scoped without changing protocol shapes — but one path (NC chunked) carries a pre-existing wart that the chroot POC's ~ username (or the app_passwords.drive_id binding) lets us finally fix.

Protocol	Size known	Quota check fires	Destination / drive known
Default multipart (POST /api/files/upload)	At request start (Content-Length / multipart size).	file_upload_service.rs:185 — check_storage_quota(caller_id, metadata.size) before any bytes are stored.	At request start (form field folder_id). Drive derives from folder.drive_id.
Native chunked (POST /api/uploads)	At session create — client declares total_size in JSON.	chunked_upload_handler.rs:213 — at session creation against declared total_size.	At session creation (folder_id in JSON). Drive derives from folder.drive_id.
NextCloud chunked (/remote.php/dav/uploads/{user}/{session}/...)	Never declared. MKCOL creates empty session, PUT chunks arrive one at a time, client decides "done".	Today: only at the final MOVE (assemble) — handle_assemble → file_upload_service::ingest_stream_to_cas → quota check on the assembled size. Wasted-bandwidth wart: a client over quota can upload GB before the server can refuse.	Today: only at MOVE (parsed from the Destination: header). With the chroot POC ({user}~{drive-uuid} username, see §9): known at MKCOL — the auth middleware already split the username. With app_passwords.drive_id binding: known at MKCOL — the credential row pins the drive.
Delta protocol (/api/files/delta/*)	At negotiate (client provides manifest with total_size).	delta_upload_service.rs:331 — at commit against total_size.	At negotiate (target file_id or folder_id). Drive derives accordingly.

Decision — per-chunk incremental quota check on the NC chunked path

The three non-NC paths trivially pivot to drive-scoped quota: replace check_storage_quota(caller_id, size) with check_drive_quota(drive_id, size). Destination is known at handler entry; drive falls out of the destination's drive_id column. No protocol change.

For NC chunked, the Drive migration also closes the wasted-bandwidth wart because the drive identity is now known at MKCOL (via ~ username or app-password binding — either NC credential-side scheme from §9 surfaces it). Approach:

1. MKCOL guard — if drive.used_bytes >= drive.quota_bytes, refuse the session creation with 507 Insufficient Storage. No point letting the client even start.
2. Per-chunk PUT check — track cumulative bytes received in the session (sum of on-disk chunk sizes, maintained by the chunked-uploads service). On each PUT, before writing the chunk:

   if drive.used_bytes + session.bytes_so_far + chunk.size > drive.quota_bytes:
       refuse with 507 Insufficient Storage
   

   The first chunk that would push us over is refused; client sees the error within one chunk's worth of wasted upload (typically a few MB) instead of after the whole multi-GB file.
3. Assemble-time re-check stays as a defence-in-depth (in case two concurrent sessions on the same drive each got past the per-chunk check but their sum exceeds quota at MOVE). This matches today's structure.
4. Unlimited quota (quota_bytes IS NULL) short-circuits all three checks — no work.

The per-chunk check is O(1) amortised: each session tracks its cumulative size as it goes. The drive's used_bytes is read from the row once per chunk; with the v0.7.0 incremental-update pattern (b5b80549, d6987329) that's a single primary-key lookup, not an aggregate query.

Net effect on NC clients: nothing changes for in-quota uploads; over-quota clients get a clear 507 within seconds instead of after the whole upload finishes.

Editor-role delete and trash — call out the UX tension

§4's role bundle gives Delete only to owner. That means in a shared drive, an editor who uploads a typo file CANNOT send it to trash themselves — they have to ask an owner. This is already flagged as Open Question 4 (revisit before D2) and the answer there determines the trash UX for editors too. If editors get a Delete capability (or a dedicated "trash own content" capability), the trash mutation rules become "trash your own files" + "drive owners can act on anyone's trashed files". Until that's decided, the conservative answer above (owner-only mutations) holds.

14. File provenance — created_by / updated_by

Today storage.files.user_id (and storage.folders.user_id) quietly doubles as both the ownership pointer (whose files are these?) AND the provenance signal (who created this?). The Drive migration cleanly separates ownership onto drive_id, but provenance has to come with us — in a shared drive where Ed, Alice, and Bob all upload files, "who put this here?" remains a load-bearing question for UI, audit, and account-cleanup workflows.

The split:

-- on both storage.folders and storage.files:
drive_id     uuid NOT NULL                       -- ownership
created_by   uuid NULL FK → auth.users(id) ON DELETE SET NULL
created_at   timestamptz NOT NULL DEFAULT now()  -- existing
updated_by   uuid NULL FK → auth.users(id) ON DELETE SET NULL
updated_at   timestamptz NOT NULL DEFAULT now()  -- existing

• created_by is set once at row insert (every upload path: multipart, native chunked, NC chunked, streaming CDC, delta, instant-upload-by-hash) — the caller_id stamps it. Never changes after.
• updated_by is set whenever updated_at is touched — rename, overwrite, move, restore from trash, PROPPATCH on favorites. Same write-path discipline as updated_at today.
• ON DELETE SET NULL on both FKs. When a user is deleted, files they created or edited in shared drives stay (they belong to the drive, not the deleter); the FK nulls out, the UI renders "Unknown user" (or "Deleted user" with a small tombstone table — future polish, see Open Question 12).

Why this lands in D0, not D7

If we waited until D7 to introduce these columns, every existing file/folder row would have NULL created_by after the migration — provenance permanently lost for pre-D7 content. Adding the columns in D0 and backfilling from user_id during the dual-write phase gives every existing row a real created_by value (the user we know created it, because that's what user_id meant). New writes during the dual-write window populate both user_id AND created_by / updated_by. By D7 the columns are self-sufficient and dropping user_id loses nothing.

UI display semantics

• File details panel: "Created by Alice on 2026-01-15", "Last edited by Bob 3 hours ago" — both fields drive a normal user avatar + name lookup. NULL → "Unknown user" placeholder.
• Activity log on a shared drive: aggregates updated_by over recent rows to show "who's been active here lately".
• Account-cleanup workflow: when an admin deletes a user, show a pre-flight summary "Bob authored 47 files and last edited 12 more across drives X, Y, Z — proceeding will mark those entries as authored by 'Deleted user'." Lets the admin choose to reassign or simply confirm.

Engine touch-point

The "who touched updated_at" rule applies uniformly across all mutation paths. Centralise it: every service that bumps updated_at must also set updated_by = caller_id in the same SQL statement. The FileRepository::update_* and FolderRepository::update_* methods are the natural choke points — a single audit reveals every callsite to verify.

The async tree_etag_queue (v0.7.0) propagates an etag up the ancestry but does NOT propagate updated_by — ETags are fingerprints of structure, not authorship. Only the direct mutation site updates updated_by.

Migration strategy

A drive-id column on every resource is a database surgery touching every storage query. We phase it for safety:

Phase A — additive (PR D0)

1. Create storage.drives and storage.drive_members.
2. Add drive_id uuid NULL to storage.folders and storage.files.
3. Per-user root-folder sweep: for each internal user, list every storage.folders row where parent_id IS NULL AND user_id = <this user>. Exactly one is expected to be My Folder - <username>; any extras are SQL-created siblings (see §10).
   • The My Folder - <username> row → becomes the default personal drive: INSERT INTO storage.drives (name='Personal', kind='personal', default_for_user=<user>, quota_bytes=<user.storage_quota_bytes>) and insert one (drive_id, user=<user>, role='owner') member row.
   • Every other sibling row → becomes a fresh secondary personal drive: kind='personal', default_for_user=NULL, name carried over from the folder's name, quota_bytes=<user.storage_quota_bytes>, and one (drive_id, user=<user>, role='owner') member row. Membership rules from §2 apply (single-owner, no add_member); the user can later promote one to kind='shared' to invite collaborators.
4. Promote children, drop the wrapper: for every folder/file row that has parent_id = <a root row from step 3>, set drive_id = <that root's new drive id> and parent_id = NULL (the drive itself is the new root, not a folder). Then DELETE the root folder rows from step 3 — they no longer exist as folders, the drive replaces them.
5. Cascade drive_id down the tree — for every remaining folder/file row, set drive_id by walking the ancestry to whichever root the row descends from. After this step every row has the same drive_id as its parent_id's row, which chains up to a drive set in step 3/4.
6. Full path-metadata reconstruction. The path column on every row in storage.folders and storage.files gets rewritten. For rows that descended from My Folder - <username>, strip that prefix; for rows that descended from a sibling root, strip that sibling's name. The path column now contains only the in-drive path (e.g. Docs/foo.pdf, never My Folder - admin/Docs/foo.pdf).
   • This is the bulk of D0's runtime cost. Personal-drive scope = every folder/file the user owns. A 100k-file user gets 100k UPDATEs. Use a single UPDATE … WHERE drive_id = <id> per drive, not a row-at-a-time loop. The ltree-path change is what every downstream subsystem keys off, so doing this in one transaction per drive (not per row) is also a correctness boundary.
   • Downstream caches and indexes — audit each for path or path-derived keys:
     • Tantivy content index (§11) — the index does NOT store paths (see tantivy_content_index.rs: indexed fields are file_id, user_id, name (basename only), content. No path field, the wrapper folder name was never a term). So the wrapper removal alone requires no reindex. The reindex §11 calls for is driven by the schema gaining drive_id and the query filter pivoting from user_id to drive_id — NOT by the path rewrite. Same migration window, but for a different reason.
     • Thumbnail cache — if keyed by path rather than file_id, invalidate; preferably switch to file_id-keyed during this migration so the issue doesn't recur. Audit before D0 starts.
     • Folder ETag queue (async_tree_etag_queue, see Open Question 8) — flush or recompute; ETags derived from old paths are stale.
     • Recent-items / favorites — referenced by file_id, not path; probably fine. Verify.
   • On-disk storage mirror — see Open Question 10. If the filesystem layout is path-mirrored, every file moves on disk too; if content-addressable, the FS is untouched. Audit before D0 starts.
7. Verify: every row has drive_id IS NOT NULL, no row has parent_id pointing at a non-existent folder, no path value contains the legacy My Folder - prefix.
8. Add NOT NULL constraint on drive_id.

Keep user_id on resources alongside drive_id for the entire Phase A release cycle. Code is updated to read drive_id everywhere; user_id is dual-written for one release as a safety net. If something breaks we can roll back without data loss.

Pre-flight checks the migration script runs before any writes:

• Report how many sibling-root folders exist per user. Don't refuse — extras become drives — but surface the count so an operator can sanity-check ("Ed has 4 root folders, expected ≤1; verify those are real and intended before promoting them to drives").
• Refuse if any sibling root folder is literally named drives (would collide with the reserved URL segment on the native /webdav/drives/<uuid>/... surface). Operator renames first.
• Refuse if any user has storage_used_bytes > storage_quota_bytes by an amount that wouldn't fit the destination drive's quota semantics (sanity check).

Phase B — cleanup (PR D7, one release later)

1. Drop user_id from storage.folders and storage.files.
2. Drop dual-write code paths.
3. Deprecate auth.users.storage_quota_bytes (or drop — quotas live on drives now).

Phase B is the point of no return; deferring it by one release gives us a real rollback window while the new model bakes in production.

PR sequencing

PR	Scope	Risk
D-Prep — role_grants refactor	access_grants → role_grants schema migration with role-bundle semantics. Manage Permission added to the enum + role bundle. Engine reads role_grants only; access_grants removed (after one dual-write release if compat is needed). API gains role parameter on grant endpoints; audit log emits one role_grant.* event per role assignment instead of N permission events. No Drive concept yet. Sets the foundation that all subsequent PRs build on. Data shape confirmed: empirical audit shows >99% of existing access_grants rows already cluster into the standard bundles (viewer/editor/owner) — the migration is mechanical for the vast majority of data; the <1% edge cases get absorbed by shipping commenter and contributor roles on day one or get an explicit per-row migration decision logged.	Medium — touches the load-bearing authorisation table, but the data shape removes the main migration risk
D0 — foundation	storage.drives schema (no drive_members — uses role_grants from D-Prep); Drive domain entity; migration creating personal drives + backfilling drive_id on every resource; read-only GET /api/drives listing the caller's drives (single query: SELECT … FROM role_grants WHERE subject_id=$caller AND resource_type='drive'). Dual-write user_id alongside drive_id for safety. No new UI. Every upload path stamps drive_id at insert: classic multipart (file_handler::upload), chunked NC (uploads_handler), streaming CDC (upload_ingest), delta upload (delta_upload_service), instant upload by hash. Tantivy reindex (see §11) is part of this PR. Provenance columns added (see §14): created_by and updated_by on both storage.folders and storage.files, FK to auth.users with ON DELETE SET NULL; backfilled from user_id so pre-Drive content has provenance from day one; every mutation path that touches updated_at also sets updated_by.	High — every storage query touches, all upload paths touched
D1 — UI switcher + URL routing	Sidebar drive picker, /drive/<uuid>/<folder-id> frontend routes, default-drive redirect from /. WebDAV path dispatcher recognising drives/<uuid> as the drive-explicit prefix on both /webdav/ and /remote.php/dav/.	Medium
D2 — drive membership API + per-drive trash auth	POST /api/drives/{id}/members, DELETE, PUT for role changes — thin handlers that translate to role_grants INSERT/DELETE/UPDATE with resource_type='drive'. Resource::Drive(Uuid) (added in D-Prep at the enum level) gets its specialised handler surface here. Shared-drive last-owner protection. Group-as-subject support reuses the existing subject_groups machinery. Personal-drive guards (add_member, remove_member, delete_drive refuse on kind='personal' — see §2). Per-drive trash authorisation (§12): trash listing filters by drive(s) the caller can read; trash mutations (send/restore/permanent-delete) require role='owner' on the drive; storage.trash_items VIEW updated to surface drive_id; orphan/aborted-upload sweep becomes per-drive.	Medium
D3 — group-owned shared drives	"Create shared drive" flow — admin or group owner triggers, drive created with kind='shared', initial owner row is the group. Group-deletion guard refuses if the group is the last owner of any drive. Drive-rename, drive-delete.	Low
D4 — per-drive quota	Move storage accounting off auth.users.storage_used_bytes onto storage.drives.used_bytes. Re-point the existing per-user incremental CTE (introduced in v0.7.0 — see b5b80549, d6987329) at drive rows; don't reinvent the counting logic. Upload paths check drive.quota_bytes instead of (or in addition to) the user's quota for the dual-write window. Per-chunk incremental quota check on the NC chunked path (see §13): MKCOL refuses when the drive is already over quota; each PUT chunk runs an O(1) used + session_so_far + chunk_size > quota test and refuses with 507 within one chunk of wasted upload. Closes a pre-existing wart where NC clients could upload GB before learning they were over quota. Reconciliation job runs once per day to fix drift.	Medium
D5 — policies	JSONB policies column + enforcement at the four known callsites. Owner-only UI in drive settings. Ship policies one at a time if you want fine-grained rollout — forbid_public_links first (lowest risk), then forbid_external_sharing, then forbid_sharing, then forbid_cross_drive_move.	Low
D6 — cross-drive move + audit	Move folder/file between drives (allowed by default; gated by forbid_cross_drive_move policy on the source drive). Audit events for every drive lifecycle event (drive.created, drive.member_added, drive.member_removed, drive.policy_changed, drive.deleted, resource.moved_between_drives).	Low
D7 — back-compat sweep	Drop user_id from storage.folders / storage.files. Drop dual-write code. Drop or deprecate auth.users.storage_quota_bytes. Provenance columns (created_by, updated_by) stay — they were populated from D0 and are now the sole source of authorship signal.	Low — but the point of no return

Approximate total: 4–6 weeks of focused work, depending on test coverage depth.

Out of scope for v1 (worth noting so we don't accidentally invite scope creep)

• Timeboxed session policy — drives that auto-lock after N minutes. Big middleware lift.
• End-to-end encryption policy — client-side encryption with server holding only ciphertext. Massive scope.
• Per-drive sync targets — sync client design ("1 drive = 1 target like 'family-computer'"). Schema-friendly today (drive has stable UUID), implementation is its own design.
• Cross-drive search UI — start with per-drive scoping. "Search everywhere" comes later.
• Drive templates — "create a drive pre-populated with these folders" is nice but not foundation work.

Open questions to revisit before D0 lands

1. Naming of the default personal drive.

   • Locked: "Personal" (i18n key, neutral, doesn't break on username rename).
   • But: should it be renameable by the user? Default-rename allowed? I'd say yes — drive name is just a label.

2. auth.users.storage_quota_bytes — drop or keep?

   • Drop entirely (cleanest).
   • Keep as the default initial quota for newly-created personal drives (so admins still have a single tunable).
   • I lean toward keep-as-default-initial.

3. Can a user be a member of their own personal drive in more than one way? (e.g. directly AND via a group they belong to)

   • Should the membership rows allow that? Or dedup?
   • Easy answer: allow; permission resolution naturally unions, so duplicate paths to the same role are idempotent.

4. What happens when you DELETE a folder/file in a shared drive you have only editor role on?

   • Today: ReBAC checks Delete permission on the resource.
   • With drives: editor role implies Create + Update + Comment but not Delete (per the role-bundle table above).
   • So editor cannot delete by default. Should they? Some teams want "editor can do anything except change drive settings". Worth a dedicated decision before D2 — possibly add a separate "can delete" toggle, or split editor into editor / contributor.

5. Drive icons / colour customisation — visual differentiator between drives in the sidebar. Out of scope for v1 but worth noting; the drives table can carry a small display JSONB column that accumulates this kind of cosmetic config without schema churn.

6. WebDAV path resolution edge case: when a user is a member of a shared drive and someone shares a single file inside it explicitly with them via a per-resource grant, what path do they see in their client?

   • The drive's path (they have access via membership), full stop.
   • Per-resource grants are additive; they don't create a separate "shared with me" listing for files that already live in a drive the user can access.
   • Confirm during D2 that this is what users expect.

7. Search-everywhere from the file picker. When a user goes to share a file, today the picker lists their own files. With drives, should the picker default to "current drive" or "all drives I have access to"? UX call, not a foundation decision.

8. async_tree_etag_queue — drive-pinning assumption audit. v0.7.0 introduced migrations/20260626000000_tree_etag_statement_triggers.sql

   • 20260627000000_async_tree_etag_queue.sql for ETag propagation up folder ancestry. The queue likely keys off folder path / owner; before D0 starts, confirm it doesn't embed assumptions that fold drive_id away (e.g. computing ancestry across a path that crosses a drive boundary). 5-minute audit to lock the question down.

9. NC credential ↔ drive binding default. Section 9 leaves open whether the Login Flow v2 picker defaults to issuing {user}~{uuid} Basic Auth usernames (option 1) or auth.app_passwords.drive_id-bound app-passwords (option 2) for non-personal drives. Decide before D1 ships; the answer determines whether auth.app_passwords gets a new column or not.

10. On-disk storage mirror — does the file path under OXICLOUD_STORAGE_PATH change too? Phase A step 6 strips the My Folder - <username>/ prefix from storage.folders.path / storage.files.path columns. If the on-disk layout mirrors these paths (<storage>/<user_id>/My Folder - admin/Docs/foo.pdf), the migration also has to mv every file on disk. If on-disk is content-addressable (BLAKE3-keyed), the columns can be rewritten without touching the filesystem. Audit the storage adapter before starting D0 and decide whether the migration script:

    • just renames the path columns (CAS layout — cheap), or
    • renames the path columns AND issues a mv per file (path-mirrored layout — expensive on big instances). The blob store is content-addressable as of v0.7.0 so most file content lives under .blobs/<hash[..2]>/<hash> and is already wrapper-agnostic; the concern is only the metadata-projection / thumbnail-cache trees if they're path-shaped.

11. Promoting sibling root folders — UX after migration. Users whose home was a single My Folder - <username> end up with one drive (Personal). Users with SQL-added siblings end up with multiple drives, one named per the original folder name. The drive name carries over verbatim — should the migration log who got more than one drive, so an operator can DM them and explain the new picker? Operational nicety, not a correctness concern.

12. Deleted-user tombstone for provenance. §14 sets created_by / updated_by to NULL when the referenced user is deleted (ON DELETE SET NULL). The UI then shows "Unknown user", which is correct but information-poor — for compliance / audit / "who left this?" purposes, a small deleted_users tombstone table (id, last_known_username, deleted_at) would let the UI render "Bob (deleted 2026-04-12)" instead of just "Unknown user". Out of scope for v1 but easy to add later without schema rework (NULL created_by stays NULL; a parallel lookup against the tombstone table on display).

Existing code to reuse

• ReBAC Resource enum at src/domain/services/authorization.rs:74 already has a tagged-union shape; adding Drive(Uuid) is one variant
  • from_parts arm + type_str arm.
• ReBAC Permission enum already has the bundle we need (Read, Create, Update, Delete, Share, Comment). The role-to-bundle mapping for drives lives in a new drive_role.rs helper.
• PgAclEngine Moka cache at src/infrastructure/services/pg_acl_engine.rs:88 handles ReBAC grant caching. The drive-role check piggybacks on the same cache with a separate keyspace (drive_perm:<user>:<drive>:<perm>).
• SubjectGroupService::list_transitive_users at src/application/services/subject_group_service.rs:385 already expands a group to its transitive user members. The drive-membership check uses this to resolve group-owner subjects.
• folder_service::create_home_folder at src/application/services/folder_service.rs:644 is where the per-user wrapper folder is created today. Post-migration this function goes away — there is no wrapper folder anymore. The user-create lifecycle hook now creates a Drive row directly and inserts the owner-role member row. The lifecycle path is the same; the work it does shrinks.
• NC path resolver nc_to_internal_path at src/interfaces/nextcloud/webdav_handler.rs:51 and the native resolver resolve_webdav_path at src/interfaces/api/handlers/webdav_handler.rs:188 are the two callsites that learn about drives. Both gain a "drive context" parameter resolved from the URL prefix (/files/<u>/ or {user}~{uuid} for NC; /webdav/ or /webdav/drives/<uuid>/ for native). Neither resolver prepends My Folder - <user>/ anymore — the storage path IS the in-drive path. Both functions also get simpler, not more complex, despite gaining the drive parameter (the personal-vs-shared branch is now a metadata lookup, not a path-shape decision).
• MagicLinkInviteService and the share-notification pipeline (RecipientNotificationService) need the new policy checks (forbid_external_sharing, forbid_sharing) wired in at their respective callsites.
• Migration timestamp convention: as of v0.7.0 the head migration is 20260702000000_drop_dead_file_indexes.sql, and 20260701000000_content_search_index.sql already exists (the Tantivy index). D0's migration becomes 20260801000000_drives.sql (or whatever date D0 actually starts) — the original 20260701000000_drives.sql slot is taken.

Verification

Each PR carries its own verification block. The bar across all of them: (a) new behaviour proven by a focused test, (b) the existing Hurl + Playwright baselines still pass green (bash tests/api/run.sh && bash tests/webdav/run.sh && cd tests/e2e && npm test), (c) cargo fmt && cargo clippy --all-features --all-targets -- -D warnings clean.

D-Prep

• Unit: role_bundle(role) returns the expected permission set for each role; roles_implying(permission) returns the expected role list; round-trip a grant insert→read→compare for every role.
• Data audit: query access_grants and confirm that >99% of rows cluster into the standard bundles (the empirical figure that unlocked Sequence A). Log the <1% edge cases per row for review.
• Migration round-trip: roll forward against a populated DB → every prior access_grants row is represented by exactly one role_grants row → roll back → original access_grants rows recovered byte-identically.
• API: new Hurl test tests/api/role_grants.hurl —
  • POST /api/grants with role='editor' creates a single row with the expected bundle when expanded.
  • PUT /api/grants/{id} with role='viewer' is atomic (no race window where the user has zero permissions).
  • Compat shim: POST /api/grants with the legacy permission field still works for one release and maps to the closest role.
  • Audit log emits role_grant.created, role_grant.role_changed, role_grant.revoked events with the role name carried through.
• UI smoke (Playwright): My Shares dialog renders roles instead of permission checkboxes; share modal preset buttons map to roles; changing a member's role from editor → viewer fires exactly one PATCH and the UI reflects the change without a race-window blank state.
• All existing Hurl + WebDAV + Playwright tests still pass — the refactor must be invisible to every non-grant-handling test.

D0

• Unit: Drive entity (kind + default_for_user CHECK constraints), default_for_user partial unique index. Personal- drive add_member / remove_member / delete_drive all refuse cleanly with the expected DomainError.
• Migration round-trip: roll forward against a populated DB → every existing folder/file row has drive_id set (no NULLs); every user has exactly one drive with default_for_user set; sibling root folders became secondary kind='personal' drives; every storage.folders.path and storage.files.path value has the My Folder - <username>/ prefix stripped → roll back via sqlx migrate revert → drive_id column gone, user_id intact thanks to dual-write, original paths recovered.
• Storage check: post-migration bash tests/api/storage_cleanup_check.sh still reports a clean tree (no orphans).
• Tantivy reindex: every indexed doc carries a drive_id; search query filtered by drive_id ∈ caller's drives returns the expected hits; cross-drive isolation confirmed (search as Alice, Bob's content never appears).
• API: tests/api/drives_foundation.hurl — admin lists /api/drives, sees their default personal drive with the correct quota, kind='personal', default_for_user matching their own uuid. Creating a folder still works; the folder's drive_id matches the personal drive.
• All upload paths set drive_id: targeted Hurl tests for multipart, native chunked, NC chunked, delta upload, instant upload by hash. Each verifies the resulting file row has the expected drive_id.

D1

• Routing: cargo build clean; WebDAV dispatcher routes /webdav/drives/<uuid>/... correctly; /webdav/<path> still resolves to the caller's default drive (back-compat).
• NC client back-compat: a real NC sync client pointed at /remote.php/dav/files/admin/ continues syncing the user's default personal drive without reconfiguration. The chroot POC's ~ username (or app-password binding) lands a sync into the chosen drive transparently.
• Manual smoke: open /, get redirected to /drive/<default-uuid>. Click sidebar drive switcher → URL updates, listing reloads. Drive picker shows all of the caller's drives (default first), each with its quota usage.
• Playwright: a new tests/e2e/drive-switching.spec.ts exercises sidebar → URL → listing → cross-drive isolation (folders in drive A don't appear in drive B's listing).

D2

• Membership API: POST /api/drives/{id}/members with user, with group, and with role changes; refuses on personal drives; shared-drive last-owner protection. Group expansion (transitive members count toward the owner total).
• Trash per drive: trash listing scopes correctly to drive(s) the caller can read; mutations refuse without owner role; the storage.trash_items VIEW surfaces drive_id.
• Updated NC + WebDAV regression baselines — the 105+ scenarios in BASELINE_TESTS_NC_WEBDAV.md still pass green; per-drive trash and membership changes don't regress existing protocol behaviour.

D3–D7

• Per-PR verification authored when the PR is drafted. Each PR adds at least one new Hurl/Playwright test for the headline capability and proves zero regression on the previous baselines.

Cross-cutting regression — runs on every Drive PR

A standing checklist independent of the headline capability of each PR:

1. bash tests/api/run.sh green (>100 scenarios).
2. bash tests/webdav/run.sh green (NC + native WebDAV baselines).
3. cd tests/e2e && npm test green (Playwright).
4. tests/api/storage_cleanup_check.sh clean.
5. No new cargo clippy warnings.
6. Tantivy index returns no cross-drive results for any caller.
7. /api/dedup/stats shows blob ref-counts consistent with the number of files referencing each blob across all drives.

UI design — outline for D1 and D3

The Drive concept reshapes three load-bearing UI elements. Each gets a small design pass alongside the relevant PR — the bullets here lock the intended shape; the pixel work happens when D1 / D3 draft.

Sidebar — drives as children of a "Drive" section

Today the sidebar shows a single root view (the user's home folder). Post-Drive it gains a top-level Drive section whose children are the drives the caller has access to:

📁 Drive
  ⭐ Personal                ← kind='personal', default_for_user=caller  (★ marks default)
     Family Archive          ← kind='personal', secondary (no star)
     Engineering             ← kind='shared',  caller is owner/editor/viewer
     2025 Marketing Sprint   ← kind='shared'
  Recent
  Favorites
  Shared with me
  Trash

• The user's default personal drive is marked with a star (or bolded — UI choice). Clicking it lands on the default landing view (today's "Files" experience).
• Other drives — secondary personals, shared drives — appear below with the same visual weight. Clicking switches the context (URL changes to /drive/<uuid>/..., listing reloads).
• The sidebar is collapsible per-drive; users with many drives can hide the drives they aren't actively in.
• No drive icons / colours in v1 (deferred to a future polish PR — see "Out of scope" item 5).
• The "Drive" section header itself is non-interactive (just a grouping label); the action affordance is "Create shared drive" via the + button at the end of the list (admin / group-owner scoped; lands in D3).

Breadcrumb — drive-rooted

Today's breadcrumb is path-rooted: Home / Docs / Q3 / Report.pdf. Post-Drive the breadcrumb starts at the selected drive:

[Personal ▾] / Docs / Q3 / Report.pdf

• The drive name is the first element. Clicking it returns to that drive's root listing.
• The ▾ chevron next to the drive name opens a quick-switcher picker (same list as the sidebar). Lets users jump between drives without using the sidebar.
• For paths inside shared drives, the drive name still leads: [Engineering ▾] / Specs / Q3 OKRs.md.
• The breadcrumb's overflow / truncation behaviour for deep paths is unchanged from today — only the root element is new.
• Drive name follows server-side rename — the breadcrumb queries the drive's current name; renaming the drive updates the breadcrumb on next reload without any client-side cache work.

"Owners" section — review and redesign

Today's UI has an "Owner" surface in several places (file details sidebar, share dialog, folder properties). It currently shows "the user who owns this file" — a single name.

Post-Drive, ownership has multiple shapes:

• For a file in a personal drive: still one owner (the drive's sole user-owner). Display stays the same — "Owner: Ed".
• For a file in a shared drive: ownership is the drive's owner- role members (possibly multiple users + groups). Display becomes "Owner: Engineering team (3 members + 2 groups)".
• For a drive itself (when displayed in a settings view): same as above, but in a list form: "Owners: Ed, Alice, Engineering group".

Open questions for the D3 PR to settle:

• Show the drive name as the effective owner? "Owner: Engineering" reads cleanly but conflates "the drive" with "the drive's owners" — clearer for end users, less precise.
• Should the file details sidebar expand owners on click? Click "Engineering team" → see the owner roster. Useful for large drives where the owner list doesn't fit inline.
• Audit/My Shares dialog: the "Shared with me" view currently groups by sharer. Post-Drive it can group by drive instead (your shared-drive access shows once per drive, not once per file). UX win — decide which grouping is default and whether both are togglable.

These three UI surfaces are independent enough that they can ship in separate PRs (sidebar in D1, breadcrumb in D1, owners review in D3 alongside the create-shared-drive flow). The sidebar and breadcrumb are essentially mechanical given the new model; the owners review is the only one with genuine design questions.

File map (anticipated, not yet created)

migrations/
  20260730000000_role_grants.sql            ← D-Prep (rename of access_grants
                                              to role_grants with role bundles)
  20260801000000_drives.sql                 ← D0 (drives table only;
                                              membership is rows in role_grants)
  20260901000000_drop_user_id_on_resources.sql ← D7

src/domain/entities/
  drive.rs                                  ← D0
  role.rs                                   ← D-Prep (role enum + bundle map)

src/domain/services/
  authorization.rs (modify)                 ← D-Prep adds `Manage` Permission +
                                              `Resource::Drive(Uuid)` variant

src/application/services/
  drive_service.rs                          ← D0–D3 (CRUD + policy enforcement,
                                              membership operations translate
                                              to role_grants writes)

src/infrastructure/repositories/pg/
  drive_pg_repository.rs                    ← D0
  role_grant_pg_repository.rs               ← D-Prep (replaces
                                              access_grant_pg_repository)

src/infrastructure/services/pg_acl_engine.rs (modify)
  reads role_grants only                    ← D-Prep
  Resource::Drive routing                   ← D0

src/interfaces/api/handlers/
  grant_handler.rs (modify)                 ← D-Prep (accepts role parameter)
  drive_handler.rs                          ← D0 (list), D2 (members), D3 (create/delete shared)

src/interfaces/api/handlers/webdav_handler.rs (modify)
  drive-aware path resolution               ← D1

src/interfaces/nextcloud/webdav_handler.rs (modify)
  drive-aware path resolution               ← D1

static/js/views/drive/                      ← D1 (sidebar switcher, drive view)
static/js/model/drives.js                   ← D1 (REST client)
static/css/components/driveSwitcher.css     ← D1

Glossary (for the next reader)

• Drive — a top-level container that owns folders and files.
• Personal drive — the auto-created drive a user gets at registration. One per internal user. kind='personal'.
• Shared drive — a drive whose membership includes at least one group (or multiple users). kind='shared'.
• Drive member — a row in storage.role_grants with resource_type='drive', carrying a subject (user or group) and a role. There is no separate drive_members table — see the D-Prep prerequisite at the top of this plan for the storage pivot.
• Owner / editor / viewer — drive roles. Map to ReBAC permission bundles for resources inside the drive.
• Drive policy — JSONB key on the drive that toggles a sharing / movement restriction.
• Drive context in WebDAV — the drive whose root the request is rooted at. Native WebDAV resolves it from the URL prefix (/webdav/<path> → caller's personal drive, /webdav/drives/<uuid>/<path> → explicit drive). NC resolves it from the credential (Basic Auth {user}~{uuid} username, or the auth.app_passwords.drive_id binding — see §9).
• Wrapper folder — historical name for My Folder - <username>, the folder created at registration via format!("My Folder - {}", username). Retired in the Drive migration: drive root replaces it. Every reference to "wrapper" in older comments / docs is by definition pre-Drive.