feat(drive): improve Drive model

now Drive is purely a metadata each drive has always a root folder this model minimize Oxicloud changes, and simplify the Drive name is simply the folder's root's name note: owner of Drive has more permission that an owner of the root folder
2026-06-18 23:02:17 +02:00
parent eab7a609b9
commit 16ea08b093
26 changed files with 1067 additions and 460 deletions
@@ -176,17 +176,35 @@ layer (`DriveService` enforces the personal-drive invariants, etc.)
 - A shared drive can have **0 viewers** and **0 editors** — only
  the ≥1-owner invariant matters.
-### 3. Drive entity
+### 3. Drive entity — pure metadata + a 1:1 root folder
 A drive is a **metadata-only holder** (quota, kind, policies, default flag)
 paired 1:1 with a *root folder* that owns the drive's visible identity
 (name, path materialisation, ltree anchor). The drive itself has no
 `name` column — every property the user thinks of as "the drive"
 (its display name, its containing children, its location in the
 ltree) lives on the root folder row.
 This is the Unix-philosophy split: the *filesystem volume* is the drive
 (quota, policies, ownership metadata); the *mount point* is the root
 folder (name, hierarchy, paths). Clients interact with the root folder
 through the standard folder API — no special "drive root" endpoint, no
 polymorphic creation surface, no "create at drive vs in folder" duality.
 ```sql
 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 '{}'
    -- The drive's mount-point folder. Nullable AT THE COLUMN TYPE LEVEL
    -- only because the column is set mid-statement during atomic
    -- creation (see "Atomic creation" below) — invariant: after any
    -- successful create_personal_drive() call, this is non-NULL. Code
    -- that reads drives can treat it as Uuid in Rust.
    root_folder_id    uuid NULL FK → storage.folders(id) ON DELETE CASCADE
    created_at        timestamptz NOT NULL DEFAULT now()
    updated_at        timestamptz NOT NULL DEFAULT now()
    -- `default_for_user` may ONLY be set on personal drives.
@@ -199,6 +217,35 @@ CREATE UNIQUE INDEX drives_default_for_user_idx
    WHERE default_for_user IS NOT NULL;  -- one DEFAULT personal drive per user
 ```
 #### Drive name lives on the root folder
 `storage.drives` has no `name` column. The drive's display name is
 `SELECT f.name FROM storage.drives d JOIN storage.folders f
 ON f.id = d.root_folder_id WHERE d.id = $drive_id`.
 Why this is the right shape:
 - **Single source of truth.** No duplication between `drives.name` and
  `folders.name`, no drift risk, no decision about which side to
  serve when they differ.
 - **Renaming is the standard folder API.** `PATCH /api/folders/<root_id>`
  with a new name renames the drive. No separate
  `PATCH /api/drives/<id>/name` endpoint. The lifecycle / cascade
  / search-index behaviour that already exists on folder rename
  applies automatically.
 - **No "rename the drive but not its mount point" footgun.** They're
  always in sync because they're the same column.
 Identity is still carried by `kind` + `default_for_user` — *not* by
 the name. UI and NC default-drive resolution query on `kind` /
 `default_for_user`, never on `name = 'Personal'`. Renaming "Personal"
 → "Ed's space" preserves identity; only the label changes.
 The migration-time default for personal drive root folder names is
 `'Personal'`. Secondary personal drives (sibling roots from the M2
 backfill — see §10) carry over whatever name the original sibling
 root folder had.
 #### Two orthogonal properties: `kind` and `default_for_user`
 - **`kind`** = drive capability shape (see §2 for the rules):
@@ -229,24 +276,123 @@ 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`
+#### Atomic creation — single transaction, four writes
-`name` is owner-editable for every drive (personal or shared). A
+A drive and its root folder reference each other circularly:
-user who renames their drive from "Personal" → "Ed's space" does
+`storage.drives.root_folder_id` points at `storage.folders.id`, and
-**not** stop having a personal drive, and does not stop having a
+`storage.folders.drive_id` points at `storage.drives.id`. Creating
-default. The `kind` flag + `default_for_user` pointer carry the
+them naively could leave inconsistent half-state on a server crash
-identity; the name is purely a display label.
+mid-sequence: drive without folder, folder without drive, or either
 without an owner role_grant.
-Why this matters:
+The repo's `create_personal_drive_atomic` wraps the four writes in
- UI and NC default-drive resolution MUST query on `kind` /
+a single transaction so they commit together or not at all:
-  `default_for_user`, never on `name = 'Personal'`. The latter
+
-  would silently break the moment the user renames.
+1. INSERT drive (with `root_folder_id = NULL`) → returns drive id.
- The initial migration sets `name = 'Personal'` on the default
+2. INSERT folder (with `drive_id` = the drive's id) → returns folder id.
-  personal drive for back-compat with the label users see today;
+3. UPDATE drive SET `root_folder_id` = the folder id.
-  further renames go through the normal drive-rename endpoint
+4. INSERT role_grant (owner, subject = caller, resource = drive).
-  and persist on the same row. Secondary personal drives carry
+5. COMMIT.
-  whatever name the sibling root folder had (e.g. `Archive`,
+
-  `2024 Projects`).
+Why a transaction rather than one CTE statement: PostgreSQL's CTE
 sub-statements all read the target tables from the *same snapshot*
 — a later sub-statement's `UPDATE storage.drives WHERE id = …`
 cannot match a row inserted by an earlier sub-statement, even if
 the earlier statement returned the new id via `RETURNING`. The
 documented escape hatch (`DEFERRABLE INITIALLY DEFERRED` FKs +
 pre-generated UUIDs) is the alternative but adds constraint
 plumbing to support a single uncommon code path. A transaction is
 boring and correct.
 Crash safety: any failure between steps 1 and 4 rolls back — no
 drive without folder, no folder without drive, no drive without
 owner. Once step 5 commits, the invariant holds.
 For reference, the equivalent (broken) one-CTE form looks like:
 ```sql
 WITH new_drive AS (
    INSERT INTO storage.drives
        (kind, default_for_user, quota_bytes, policies)
    VALUES ('personal', $user_id, $quota, '{}'::jsonb)
    RETURNING id
 ),
 new_root AS (
    INSERT INTO storage.folders
        (name, parent_id, user_id, drive_id, created_by, updated_by)
    SELECT 'Personal',     -- root folder name
           NULL,            -- parent_id (this IS the root)
           $user_id,
           new_drive.id,    -- forward-ref to the drive's id
           $user_id, $user_id
      FROM new_drive
    RETURNING id, drive_id
 ),
 drive_updated AS (
    UPDATE storage.drives d
       SET root_folder_id = new_root.id
      FROM new_root
     WHERE d.id = new_root.drive_id
    RETURNING d.id
 ),
 new_grant AS (
    INSERT INTO storage.role_grants
        (subject_type, subject_id, resource_type, resource_id, role, granted_by)
    SELECT 'user', $user_id, 'drive', du.id, 'owner', $user_id
      FROM drive_updated du
    RETURNING resource_id
 )
 SELECT d.id, d.root_folder_id, d.kind, d.default_for_user,
       d.quota_bytes, d.used_bytes, d.policies,
       d.created_at, d.updated_at
  FROM storage.drives d
  JOIN new_grant g ON g.resource_id = d.id;
 ```
 Why the one-CTE form above does NOT work — and what we ship instead:
 The shared-snapshot rule (`postgresql.org/docs/current/queries-with.html`
 §7.8.2: "they cannot 'see' one another's effects on the target tables")
 breaks the `drive_updated` sub-statement. Its `UPDATE storage.drives d
 … WHERE d.id = new_root.drive_id` evaluates `WHERE d.id = …` against
 the snapshot, which doesn't contain the drive inserted by `new_drive`.
 The UPDATE matches zero rows; `RETURNING` returns zero rows;
 `new_grant` (which feeds off `drive_updated`) inserts zero role_grants;
 the final SELECT joins on an empty CTE branch and returns nothing.
 Symptoms in tests: drives exist with `root_folder_id IS NULL`, owners
 have no `role_grants` row, `/api/drives` returns `[]`.
 The fix is the four-step transaction described above. Rust:
 ```rust
 let mut tx = pool.begin().await?;
 let drive_id: Uuid = sqlx::query_scalar(
    r#"INSERT INTO storage.drives (kind, default_for_user, quota_bytes)
       VALUES ('personal', $1, $2) RETURNING id"#,
 ).bind(owner).bind(quota).fetch_one(&mut *tx).await?;
 let folder_id: Uuid = sqlx::query_scalar(
    r#"INSERT INTO storage.folders
        (name, parent_id, user_id, drive_id, created_by, updated_by)
       VALUES ('Personal', NULL, $1, $2, $1, $1) RETURNING id"#,
 ).bind(owner).bind(drive_id).fetch_one(&mut *tx).await?;
 sqlx::query("UPDATE storage.drives SET root_folder_id = $1 WHERE id = $2")
    .bind(folder_id).bind(drive_id).execute(&mut *tx).await?;
 sqlx::query(
    r#"INSERT INTO storage.role_grants
        (subject_type, subject_id, resource_type, resource_id, role, granted_by)
       VALUES ('user', $1, 'drive', $2, 'owner', $1)"#,
 ).bind(owner).bind(drive_id).execute(&mut *tx).await?;
 tx.commit().await?;
 ```
 Each statement sees the prior statements' writes (transaction-local
 visibility, not the CTE shared snapshot). FK timing works without
 `DEFERRABLE`: each FK is satisfied at the moment its row is written
 because the referenced rows already exist.
 #### Capabilities matrix
@@ -258,11 +404,12 @@ Why this matters:
 | 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 |
+| On user-delete | `ON DELETE CASCADE` via `default_for_user` FK (free) | application-layer cleanup: enumerate via `role_grants` (`subject_id=<user> AND resource_type='drive' AND role='owner'`) and delete | role_grants 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 |
 | Change `quota_bytes` | **OxiCloud admin only** (not the drive owner — §7) | **OxiCloud admin only** | **OxiCloud admin only** |
 ### 4. Roles → permission bundles
@@ -273,7 +420,7 @@ expansion:
 |---|---|
 | `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) |
+| `owner`  | `Read`, `Create`, `Update`, `Comment`, `Delete`, `Share`, *and* drive-level admin (rename, edit policies, manage members) |
 ### 5. Permission resolution — additive over `role_grants`
@@ -305,16 +452,16 @@ against the same table.
 | 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. |
+| New internal user registers | Auto-create a default personal drive (`kind='personal'`, `default_for_user=<new_user>`, `quota_bytes=<OXICLOUD_DEFAULT_QUOTA_BYTES>`) + its root folder (`name='Personal'`, `parent_id=NULL`, drive_id pinned) + the Owner role_grant (`role_grants(subject_type='user', subject_id=<user>, resource_type='drive', resource_id=<drive>, role='owner')`) — **all four writes in one CTE statement** (§3), atomic against server crash. |
 | 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. |
+| 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 owner `role_grants` row points at the user) are deleted by an application-layer pass in the same transaction. `role_grants` 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. |
+| Rename personal or shared drive | Allowed for any owner-role caller. The drive's display name lives on its root folder (§3) — rename via `PATCH /api/folders/<root_folder_id>`, not a drive-specific endpoint. |
-| Remove last owner of shared drive | Refuse — drive must always have ≥1 owner. App-layer check on `DELETE FROM drive_members`. |
+| Remove last owner of shared drive | Refuse — drive must always have ≥1 owner. App-layer check on `DELETE FROM role_grants WHERE resource_type='drive' AND resource_id=$drive AND role='owner'`. |
 ### 7. Quota model
@@ -336,6 +483,38 @@ After the cutover:
 (plus a periodic reconciliation job to fix drift, similar to the
 existing per-user accounting).
 #### Quota mutation is OxiCloud-admin only
 Changing `drives.quota_bytes` is **not** in the drive `owner` role
 bundle (§4). It requires the tenant-level OxiCloud admin role
 (`auth.users.role = 'admin'`), checked at
 `PATCH /api/admin/drives/{id}/quota` — the only callsite that
 mutates the column. Drive owners can rename, edit policies, and
 manage members; they cannot self-grant capacity.
 Why this seam matters:
 - **Resource allocation is a tenant concern, not a drive
  concern.** Storage bytes are a finite system resource the
  operator pays for. The drive owner is empowered over the
  drive's *use*; the admin is empowered over its *budget*. Same
  separation that exists today between a user and the operator
  who set `OXICLOUD_DEFAULT_QUOTA_BYTES`.
 - **Privilege-escalation seam closed.** Without this carve-out,
  any user with a personal drive (= every internal user) could
  raise their own quota by virtue of being its sole owner —
  trivially defeating the quota system.
 - **Shared-drive coherence.** A shared drive's quota is set by
  the operator at provisioning; subsequent capacity requests go
  through the admin, not the drive's group owners. Keeps the
  capacity decision auditable and out of intra-team politics.
 The admin endpoint is the same surface the operator uses today to
 change `auth.users.storage_quota_bytes`; D4 simply re-targets the
 write at `storage.drives.quota_bytes`. Audit log emits
 `drive.quota_changed` with `granted_by=<admin_user_id>` and the
 old/new values, mirroring the existing user-quota change event.
 **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
@@ -479,34 +658,57 @@ 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
+### 10. Storage paths — wrapper folder becomes the drive's root folder
 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
+Post-drives, **the wrapper isn't deleted — it's *adopted* as the
-root; folders and files that used to live inside the wrapper sit
+drive's root folder** (§3). The drive row is created alongside it
-directly under the drive with no intermediate folder:
+and points at it via `drives.root_folder_id`. The wrapper's row
 survives the migration; only its `name` is updated.
 ```
-Drive "Personal" (uuid=…, kind=personal, owner=admin) ← was the "My Folder - admin" wrapper
+Drive (uuid=…, kind=personal, default_for_user=admin)
 └── root folder (parent_id=NULL, drive_id=<drive_uuid>, name="Personal")  ← was "My Folder - admin"
    ├── Docs/
    └── aa.pdf
 ```
-Same for shared drives — they already had no wrapper:
+Shared drives follow the same shape — drive + root folder + content
 underneath:
 ```
-Drive "Engineering" (uuid=…, kind=shared, owners=group:engineering)
+Drive (uuid=…, kind=shared, owners=group:engineering)
 └── root folder (parent_id=NULL, drive_id=<drive_uuid>, name="Engineering")
    ├── Specs/
    ├── Roadmap.md
    └── archive/
 ```
-The two surfaces share one rule: **drive root = `parent_id IS NULL`
+One rule, one model: **every drive has exactly one folder where
-within the drive's `drive_id`**. The "personal vs shared" branch
+`parent_id IS NULL` AND `drive_id = <the drive>`**.
-disappears from path resolution — both kinds resolve the same way.
+
 #### Why this is a better model
 Three things converge:
 1. **No API duality.** Folder creation is always `POST /api/folders
   { name, parent_id: <id> }`. There's no polymorphic "create at
   drive vs in folder" branch — the drive's root folder is just
   another folder id from the client's perspective. The `parent_id`
   field that exists today carries over unchanged.
 2. **No path-prefix rewrite migration.** The wrapper row stays; it's
   renamed to its drive's canonical name (`"Personal"` for the
   default, the original sibling-root name for secondaries). The
   BEFORE-UPDATE path trigger fires on the rename and the cascade
   trigger automatically rewrites every descendant's `path` /
   `lpath` — no per-row UPDATE in the migration. The net cost is
   one UPDATE per drive plus the trigger's cascade.
 3. **No "this user lost their drive" failure mode.** Migration is
   safe even mid-flight — the wrapper row never disappears, just
   gains a drive_id pointer above it.
 #### Why this is client-safe
@@ -519,22 +721,48 @@ The wrapper was already invisible to WebDAV / NC clients pre-drive:
 - 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
+Post-migration the resolver chroot becomes `<drive_root_folder.path>/`
-asking for `/remote.php/dav/files/admin/Docs/foo.pdf`, the
+instead of `My Folder - <user>/`. The drive's root folder name
-resolver no longer prepends the wrapper, and the storage row's
+(e.g. `Personal`) replaces the wrapper name in the materialised
-path is now `Docs/foo.pdf` instead of `My Folder - admin/Docs/foo.pdf`.
+`path` column; the client's URL still doesn't carry it
-Net effect on the wire: zero.
+because the resolver still chroots before talking to storage. Net
 effect on the wire: zero.
-#### Why this is a better model
+#### Uniqueness constraints become drive-scoped
-The original plan kept the wrapper "for back-compat" but it has
+Pre-drive, two indexes enforce "no duplicate folder names under the
-no value beyond the storage layer (clients never see it, the
+same parent for the same user":
-filesystem mirror is happy either way). Keeping it forced path
+
-resolution to always know whether the caller is in a personal or
+```sql
-shared drive and conditionally prepend a segment. Dropping it
+CREATE UNIQUE INDEX idx_folders_unique_name
-collapses that branch and makes the personal-vs-shared distinction
+    ON storage.folders(parent_id, name, user_id)
-purely a metadata concern (kind, quota source, member shape) —
+    WHERE NOT is_trashed AND parent_id IS NOT NULL;
-**not** a path-shape concern.
+CREATE UNIQUE INDEX idx_folders_unique_name_root
    ON storage.folders(name, user_id)
    WHERE NOT is_trashed AND parent_id IS NULL;
 ```
 Both move from `user_id`-scoped to `drive_id`-scoped:
 ```sql
 CREATE UNIQUE INDEX idx_folders_unique_name
    ON storage.folders(parent_id, name, drive_id)
    WHERE NOT is_trashed AND parent_id IS NOT NULL;
 CREATE UNIQUE INDEX idx_folders_unique_name_root
    ON storage.folders(name, drive_id)
    WHERE NOT is_trashed AND parent_id IS NULL;
 ```
 This is a **correctness improvement**, not just a migration concession.
 The semantic users expect is "no duplicate names *within a drive*"
 — a folder named "Reports" in your Personal drive shouldn't preclude
 another "Reports" in a shared "Team" drive. The user-scoped
 constraint forbade that. The drive-scoped constraint allows it.
 For the root variant: post-migration each drive has exactly one
 `parent_id IS NULL` row (its root folder), so `(name, drive_id)` is
 trivially unique. The index is still worth keeping as
 defence-in-depth.
 #### Sibling root folders also become drives
@@ -551,23 +779,26 @@ 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'`,
+  personal drive's root folder**: a new drive row is created with
-  `default_for_user=<user>`, sole member = the user.
+  `kind='personal'`, `default_for_user=<user>`, the existing folder
  row gets a `drive_id` pointer (and the wrapper's name is updated
  to `"Personal"`), and `drives.root_folder_id` points back at it.
  Sole `role_grants` row: Owner, subject=`<user>`.
 - Every **other** sibling becomes a fresh **secondary personal
-  drive**: `kind='personal'`, `default_for_user=NULL`, sole
+  drive's root folder**: a new drive row with `kind='personal'`,
-  member = the user, name carried over from the folder's `name`
+  `default_for_user=NULL`, the existing folder row gets its
-  column, quota initialised from the user's quota
+  `drive_id` set and *keeps its name* (`Archive`, `2024 Projects`,
-  (`auth.users.storage_quota_bytes`) — same default as the
+  whatever), quota initialised from the user's quota
-  user's primary personal drive. Membership rules from §2 apply:
+  (`auth.users.storage_quota_bytes`) — same default as the user's
-  the user cannot invite co-owners while the drive remains
+  primary personal drive. Membership rules from §2 apply: the user
-  personal. To open the silo up, the user can later **convert**
+  cannot invite co-owners while the drive remains personal. To open
-  the secondary personal to `kind='shared'` (an
+  the silo up, the user can later **convert** the secondary
-  application-layer operation that flips the kind and lifts the
+  personal to `kind='shared'` (an application-layer operation that
-  single-user restriction so the membership API can add other
+  flips the kind and lifts the single-user restriction so the
-  users / groups).
+  membership API can add other users / groups).
- The folder row is deleted (the drive replaces it as the root).
+- **No folder row is deleted.** The wrapper rows survive the
-  Its children get their `parent_id` set to `NULL` *within their
+  migration as drive root folders; only their `drive_id` is set and
-  new `drive_id`*.
+  (for the default-Personal case) their `name` is updated.
 The chroot POC's "pick a drive at login" picker on
 `feat/nextcloud-drive` already produces the right shape for this:
@@ -918,79 +1149,99 @@ every storage query. We phase it for safety:
 ### Phase A — additive (PR D0)
-1. Create `storage.drives` and `storage.drive_members`.
+1. Create `storage.drives` (no `name` column — see §3; has
   `root_folder_id uuid NULL` populated in step 3). **No
   `storage.drive_members` table** — membership lives in
   `storage.role_grants` (created in D-Prep) as
   `resource_type='drive'` rows.
 2. Add `drive_id uuid NULL` to `storage.folders` and `storage.files`.
-3. **Per-user root-folder sweep**: for each internal user, list
+3. **Per-user root-folder adoption sweep**: for each internal user,
-   every `storage.folders` row where `parent_id IS NULL AND
+   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).
+   (see §10). Each row is **adopted in place** as a drive's root
   folder — no row is deleted, no descendant `parent_id` changes,
   no path-prefix strip across the whole tree.
   - The `My Folder - <username>` row → becomes the **default
-     personal drive**: `INSERT INTO storage.drives (name='Personal',
+     personal drive's root folder**. In one CTE statement per
-     kind='personal', default_for_user=<user>, quota_bytes=<user.storage_quota_bytes>)`
+     user (same shape as §3's `create_personal_drive`):
-     and insert one `(drive_id, user=<user>, role='owner')`
+     - INSERT into `storage.drives` with `kind='personal'`,
-     member row.
+       `default_for_user=<user>`, `quota_bytes=<user.storage_quota_bytes>`
       (no `name` column).
     - UPDATE the wrapper folder row: set `drive_id=<new drive>`
       and `name='Personal'` (renames the wrapper to the canonical
       default name; the BEFORE-UPDATE `path` trigger fires and
       cascades the new name down every descendant via the
       existing AFTER-UPDATE cascade trigger — no per-row UPDATE
       in the migration script).
     - UPDATE `storage.drives` to set `root_folder_id=<wrapper row id>`.
     - INSERT one `role_grants` row: subject=`<user>`,
       `resource_type='drive'`, `resource_id=<new drive>`,
       `role='owner'`.
   - Every other sibling row → becomes a fresh **secondary
-     personal drive**: `kind='personal'`, `default_for_user=NULL`,
+     personal drive's root folder**, same four-write CTE shape
-     name carried over from the folder's `name`,
+     except: `default_for_user=NULL`, no `name` change (the
-     `quota_bytes=<user.storage_quota_bytes>`, and one
+     sibling keeps its original name), and the Owner grant points
-     `(drive_id, user=<user>, role='owner')` member row.
+     at the same user. Membership rules from §2 apply
-     Membership rules from §2 apply (single-owner, no `add_member`);
+     (single-owner, no `add_member`); the user can later promote
-     the user can later promote one to `kind='shared'` to invite
+     one to `kind='shared'` to invite collaborators.
-     collaborators.
+4. **Cascade `drive_id` down the tree** — for every folder/file
-4. **Promote children, drop the wrapper**: for every folder/file
+   row, set `drive_id` by walking the ancestry up to whichever
-   row that has `parent_id = <a root row from step 3>`, set
+   adopted root the row descends from. After this step every row
-   `drive_id = <that root's new drive id>` and `parent_id = NULL`
+   has the same `drive_id` as its `parent_id`'s row, which chains
-   (the drive itself is the new root, not a folder). Then DELETE
+   up to a root folder whose `drive_id` was set in step 3.
-   the root folder rows from step 3 — they no longer exist as
+   Reuse the existing ltree-aware recursive helper
-   folders, the drive replaces them.
+   (`storage.copy_folder_tree`-style descent) — single
-5. **Cascade `drive_id` down the tree** — for every remaining
+   `UPDATE … WHERE` per drive, not a row-at-a-time loop.
-   folder/file row, set `drive_id` by walking the ancestry to
+5. **No bulk path rewrite.** The `path` column on descendants is
-   whichever root the row descends from. After this step every
+   untouched by this migration. The wrapper rename in step 3
-   row has the same `drive_id` as its `parent_id`'s row, which
+   (`My Folder - admin` → `Personal`) is the only path-affecting
-   chains up to a drive set in step 3/4.
+   change; the BEFORE-UPDATE folder trigger rewrites the wrapper
-6. **Full path-metadata reconstruction**. The `path` column on
+   row's own `path` / `lpath`, and the AFTER-UPDATE cascade
-   **every** row in `storage.folders` and `storage.files` gets
+   trigger propagates the new path prefix to every descendant
-   rewritten. For rows that descended from `My Folder - <username>`,
+   automatically.
-   strip that prefix; for rows that descended from a sibling root,
+   - **Downstream caches and indexes** — most are unaffected
-   strip that sibling's `name`. The path column now contains only
+     because path *content* changes only inside the renamed
-   the in-drive path (e.g. `Docs/foo.pdf`, never
+     wrapper segment (descendants reflect "Personal/…" instead of
-   `My Folder - admin/Docs/foo.pdf`).
+     "My Folder - admin/…"). Audit:
   - **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
+       `content`. No `path` field). Reindex IS still required —
-       never a term). So the wrapper removal alone requires no
+       not because of paths but because the schema gains
-       reindex. The reindex §11 calls for is driven by the
+       `drive_id` and the query filter pivots from `user_id` to
-       schema gaining `drive_id` and the query filter pivoting
+       `drive_id`. Same migration window, different reason.
-       from `user_id` to `drive_id` — NOT by the path rewrite.
+     - **Thumbnail cache** — file_id-keyed: unaffected by the
-       Same migration window, but for a different reason.
+       wrapper rename. Path-keyed entries (if any) invalidate on
-     - **Thumbnail cache** — if keyed by path rather than
+       any path change in the wrapper; flush as a precaution and
-       file_id, invalidate; preferably switch to file_id-keyed
+       switch to file_id keying during this migration if not
-       during this migration so the issue doesn't recur. Audit
+       already done.
       before D0 starts.
     - **Folder ETag queue (`async_tree_etag_queue`,** see Open
-       Question 8) — flush or recompute; ETags derived from old
+       Question 8) — recompute. The wrapper rename touches the
-       paths are stale.
+       wrapper's own ETag at minimum; ancestors-of-ancestors
       below the wrapper are structurally unchanged.
     - **Recent-items / favorites** — referenced by file_id, not
-       path; probably fine. Verify.
+       path; unaffected.
   - **On-disk storage mirror** — see Open Question 10. If the
-     filesystem layout is path-mirrored, every file moves on
+     filesystem layout mirrors `path`, the wrapper directory
-     disk too; if content-addressable, the FS is untouched.
+     itself is renamed (one `mv`) and the descendant directories
-     Audit before D0 starts.
+     don't move; the rename is atomic on the filesystem. If
-7. Verify: every row has `drive_id IS NOT NULL`, no row has
+     content-addressable, the FS is untouched.
-   `parent_id` pointing at a non-existent folder, no `path` value
+6. Verify: every row has `drive_id IS NOT NULL`; every drive has
-   contains the legacy `My Folder - ` prefix.
+   `root_folder_id IS NOT NULL` and pointing at a real folder row
-8. Add `NOT NULL` constraint on `drive_id`.
+   whose `parent_id IS NULL` and whose `drive_id` matches the
   drive's id (the 1:1 invariant from §3); no row has `parent_id`
   pointing at a non-existent folder.
 7. Add `NOT NULL` constraints: `drive_id` on `storage.folders`
   and `storage.files`. `root_folder_id` on `storage.drives`
   stays NULLable at the column level (§3 explains why — the
   atomic CTE writes NULL on the drive INSERT and populates the
   column with an UPDATE later in the same statement; a column-
   level `NOT NULL` would refuse the initial INSERT). The
   invariant "every drive has a root folder" is enforced by the
   CTE being the only creation path, not by a constraint.
   Verification step 6 checks the invariant on the populated
   dataset; ongoing enforcement is application-layer.
 **Keep `user_id`** on resources alongside `drive_id` for the entire
 Phase A release cycle. Code is updated to read `drive_id` everywhere;
@@ -1129,18 +1380,26 @@ place on `storage.files` / `storage.folders`, which already carry
   not.
 10. **On-disk storage mirror — does the file path under
-    `OXICLOUD_STORAGE_PATH` change too?** Phase A step 6 strips
+    `OXICLOUD_STORAGE_PATH` change too?** Phase A step 3 renames
-    the `My Folder - <username>/` prefix from `storage.folders.path`
+    the wrapper folder row (`My Folder - admin` → `Personal`) for
-    / `storage.files.path` columns. If the on-disk layout mirrors
+    each default personal drive; the AFTER-UPDATE trigger
-    these paths (`<storage>/<user_id>/My Folder - admin/Docs/foo.pdf`),
+    rewrites descendant `storage.folders.path` /
-    the migration also has to `mv` every file on disk. If on-disk
+    `storage.files.path` values automatically (no bulk UPDATE in
-    is content-addressable (BLAKE3-keyed), the columns can be
+    the migration script). If the on-disk layout mirrors these
-    rewritten without touching the filesystem. **Audit the
+    paths (`<storage>/<user_id>/My Folder - admin/Docs/foo.pdf`),
-    storage adapter before starting D0** and decide whether the
+    the migration ALSO has to rename the wrapper directory on
-    migration script:
+    disk — **but only the wrapper directory itself**, one `mv`
-    - just renames the path columns (CAS layout — cheap), or
+    per drive, atomic on the filesystem; no descendant `mv`
-    - renames the path columns AND issues a `mv` per file
+    needed. If on-disk is content-addressable (BLAKE3-keyed),
-      (path-mirrored layout — expensive on big instances).
+    the columns can be rewritten without touching the filesystem
    at all. **Audit the storage adapter before starting D0** and
    decide whether the migration script:
    - just lets the trigger rewrite the path columns (CAS layout
      — cheap), or
    - rewrites the path columns AND issues a single `mv` per
      drive on disk (path-mirrored layout — still cheap; only
      the wrapper directory moves, the subtree comes along for
      free).
    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
@@ -1186,11 +1445,13 @@ place on `storage.files` / `storage.folders`, which already carry
  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
+  per-user wrapper folder is created today. Post-migration the
-  function **goes away** — there is no wrapper folder anymore. The
+  function is **replaced** by a single `create_personal_drive`
-  user-create lifecycle hook now creates a Drive row directly and
+  call against `DriveRepository` that runs the §3 atomic CTE:
-  inserts the owner-role member row. The lifecycle path is the same;
+  drive + root folder (named "Personal", `parent_id=NULL`,
-  the work it does shrinks.
+  `drive_id` pinned) + Owner `role_grants` row, all in one SQL
  statement. The lifecycle path is the same; the work moves to
  the drive repository.
 - **NC path resolver `nc_to_internal_path`** at
  `src/interfaces/nextcloud/webdav_handler.rs:51` and the native
  resolver `resolve_webdav_path` at
@@ -1198,11 +1459,12 @@ place on `storage.files` / `storage.folders`, which already carry
  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>/`
+  for native). Each resolves to the drive's root folder via
-  anymore** — the storage path IS the in-drive path. Both
+  `drives.root_folder_id` and prepends that folder's `path`
-  functions also get simpler, not more complex, despite gaining
+  (after the migration this is `Personal/…` for default personal
-  the drive parameter (the personal-vs-shared branch is now a
+  drives, the original sibling-root name for secondaries, the
-  metadata lookup, not a path-shape decision).
+  shared-drive root name for shared drives). The personal-vs-shared
  branch is now a single 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
@@ -1258,12 +1520,19 @@ test`), **(c)** `cargo fmt && cargo clippy --all-features
  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;
+  every drive has `root_folder_id IS NOT NULL` and the row it
-  sibling root folders became secondary `kind='personal'` drives;
+  points at has `parent_id IS NULL AND drive_id = <self>` (the
-  every `storage.folders.path` and `storage.files.path` value has
+  1:1 invariant from §3); every user has exactly one drive with
-  the `My Folder - <username>/` prefix stripped → roll back via
+  `default_for_user` set; sibling root folders became secondary
-  `sqlx migrate revert` → `drive_id` column gone, `user_id` intact
+  `kind='personal'` drives whose root folders kept their original
-  thanks to dual-write, original paths recovered.
+  names; default-personal wrapper folders were renamed from
  `My Folder - <username>` to `Personal` and the AFTER-UPDATE
  trigger cascaded the rename down the descendant `path` values
  → roll back via `sqlx migrate revert` → `drive_id` /
  `root_folder_id` columns gone, `user_id` intact thanks to
  dual-write, wrapper folder names restored to
  `My Folder - <username>` (and the trigger cascade restores
  descendant paths).
 - **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`;
@@ -1498,6 +1767,13 @@ static/css/components/driveSwitcher.css     ← D1
  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
+  via `format!("My Folder - {}", username)`. **Adopted** in the
-  Drive migration: drive root replaces it. Every reference to
+  Drive migration: the same folder row is renamed to `Personal`
  and reused as the default personal drive's root folder
  (`drives.root_folder_id`). No row is deleted; the wrapper IS
  the root folder under the new model. Every reference to
  "wrapper" in older comments / docs is by definition pre-Drive.
 - **Drive's root folder** — the folder row pointed at by
  `storage.drives.root_folder_id`. `parent_id IS NULL`,
  `drive_id` = the drive. Every drive has exactly one (§3); the
  drive's display name lives on this folder's `name` column.
@@ -20,7 +20,6 @@
 CREATE TABLE IF NOT EXISTS storage.drives (
    id                  UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    name                TEXT NOT NULL,
    -- Discriminant. Two kinds today; extending the set is a DROP + ADD
    -- CHECK constraint pair (no separate lookup table).
@@ -36,10 +35,24 @@ CREATE TABLE IF NOT EXISTS storage.drives (
    default_for_user    UUID
        REFERENCES auth.users(id) ON DELETE CASCADE,
    -- The drive's mount-point folder. The display name lives here (drives
    -- have no `name` column — see docs/plan/drive.md §3). NULL at the
    -- column type level so the atomic creation CTE can INSERT the drive
    -- row before the root folder exists, then UPDATE this column from
    -- a later CTE branch within the same statement (a column-level
    -- NOT NULL would refuse that initial INSERT). The invariant
    -- "every drive has a root folder" is enforced by the CTE being
    -- the only creation path, plus the M2 backfill populating this
    -- column for migrated drives. Code reading this column may treat
    -- it as Uuid (not Option<Uuid>); a NULL here is a bug.
    root_folder_id      UUID
        REFERENCES storage.folders(id) ON DELETE CASCADE,
    -- Storage quota in bytes. NULL = no quota (admin override / system
    -- drives). Initial value on personal-drive creation is taken from
    -- the owner's `auth.users.storage_quota_bytes` at the application
-    -- layer.
+    -- layer. **Mutation is OxiCloud-admin only** (docs/plan/drive.md §7) —
    -- not in the drive `owner` role bundle.
    quota_bytes         BIGINT,
    -- Running total of bytes consumed. Maintained by D4's incremental
@@ -59,13 +72,19 @@ CREATE TABLE IF NOT EXISTS storage.drives (
 );
 COMMENT ON TABLE storage.drives IS
-    'Drive entity. Top-level container that owns a tree of folders/files; '
+    'Drive entity — pure metadata. The display name and mount point live '
-    'membership lives in storage.role_grants with resource_type=''drive''. '
+    'on the root folder (root_folder_id). Membership lives in '
-    'Replaced the per-user My Folder wrapper at D0 (see docs/plan/drive.md).';
+    'storage.role_grants with resource_type=''drive''. Replaces the '
    'per-user My Folder wrapper at D0 (see docs/plan/drive.md §3).';
 COMMENT ON COLUMN storage.drives.kind IS
    'personal = single-owner (no add_member); shared = multi-member with full role roster.';
 COMMENT ON COLUMN storage.drives.default_for_user IS
    'Set iff this is the user''s default personal drive. NULL on secondaries and shared drives.';
 COMMENT ON COLUMN storage.drives.root_folder_id IS
    'Drive''s root folder. NULLable at the column level only so the '
    'atomic creation CTE can write it mid-statement; populated invariant '
    'enforced by application. Display name = SELECT name FROM '
    'storage.folders WHERE id = root_folder_id.';
 COMMENT ON COLUMN storage.drives.policies IS
    'JSONB capability-flag bag; see docs/plan/drive.md §8 §15 for known keys.';
@@ -1,25 +1,29 @@
 -- ════════════════════════════════════════════════════════════════════════════
-- D0 / M2 — Drive backfill: create drives + stamp drive_id + provenance
+-- D0 / M2 — Drive backfill: adopt wrappers + stamp drive_id + provenance
 -- ════════════════════════════════════════════════════════════════════════════
-- Second of the D0 migration trio. Half (1) of the §A backfill — the safe,
+-- Second of the D0 migration trio. Implements §A of the migration plan in
-- focused half:
+-- docs/plan/drive.md — the "rename-and-adopt" model:
 --
--   * For every internal user with a root folder, create a Personal drive.
+--   * For every internal user with a root folder, create a Personal drive
--   * The folder literally named `My Folder - <username>` becomes the
+--     (metadata only — no `name` column; the display name lives on the
--     user's default Personal drive (`default_for_user = <uid>`).
+--     root folder).
--   * Any sibling root folders become secondary Personal drives
+--   * The folder literally named `My Folder - <username>` is **adopted
--     (`default_for_user = NULL`, name carried over verbatim).
+--     in place** as the user's default Personal drive's root folder:
 --     `drives.root_folder_id` points at it, its `drive_id` is stamped,
 --     and it is renamed to `Personal`. The wrapper row is NOT deleted;
 --     descendants are NOT promoted. The AFTER-UPDATE folder cascade
 --     trigger rewrites descendant `path`/`lpath` automatically when the
 --     wrapper rename fires — no bulk path UPDATE in this migration.
 --   * Any sibling root folders become secondary Personal drives'
 --     root folders (`default_for_user = NULL`, original folder name
 --     preserved). Same adoption pattern: drive_id stamped, drives.root_folder_id
 --     wired, no rename.
 --   * One owner role_grants row per new drive.
 --   * Every existing folder/file row gets a `drive_id` (cascaded down the
 --     ltree from the wrapper).
 --   * Every existing folder/file row gets `created_by` and `updated_by`
 --     backfilled from the existing `user_id` column.
 --
 -- The aggressive half (drop the wrapper folder, rewrite path columns,
 -- strip the `My Folder - <username>/` prefix from every path/lpath value)
 -- lands in M2b — kept separate so the tree-shape rewrite can be reviewed
 -- in isolation.
 --
 -- External users (`auth.users.is_external = TRUE`) are intentionally
 -- skipped — they have no root folder of their own, only role_grants
 -- against other users' resources.
@@ -56,6 +60,49 @@ BEGIN
 END $BODY$;
 -- ── Pre-flight 1b: refuse on rename collision with sibling root 'Personal' ─
 -- The default-wrapper rename in step 4 changes `My Folder - <username>` →
 -- `Personal`. The pre-M3 folder unique index is user_id-scoped
 -- (`(name, user_id) WHERE parent_id IS NULL`), so a user who already has
 -- a SQL-created sibling root literally named `Personal` would trip the
 -- index when M2 tries to rename the wrapper. Surface the collision now —
 -- operator renames the offending sibling before retrying, then it gets
 -- adopted as a secondary drive with whatever new name it carries.
 DO $BODY$
 DECLARE
    collisions BIGINT;
 BEGIN
    SELECT count(*) INTO collisions
    FROM auth.users u
    JOIN storage.folders wrapper
      ON wrapper.user_id   = u.id
     AND wrapper.parent_id IS NULL
     AND NOT wrapper.is_trashed
     AND wrapper.name      = 'My Folder - ' || u.username
    JOIN storage.folders sibling
      ON sibling.user_id   = u.id
     AND sibling.parent_id IS NULL
     AND NOT sibling.is_trashed
     AND sibling.id        != wrapper.id
     AND sibling.name      = 'Personal'
    WHERE NOT u.is_external;
    IF collisions > 0 THEN
        RAISE EXCEPTION
            'D0 backfill refused: % user(s) have both a `My Folder - <username>` '
            'wrapper AND a sibling root named ''Personal''. The wrapper rename '
            'step would collide on the user_id-scoped folder unique index. '
            'Rename the offending sibling first. Query to inspect: SELECT u.id, '
            'u.username FROM auth.users u JOIN storage.folders w ON w.user_id=u.id '
            'AND w.parent_id IS NULL AND w.name=''My Folder - ''||u.username '
            'JOIN storage.folders s ON s.user_id=u.id AND s.parent_id IS NULL '
            'AND s.id!=w.id AND s.name=''Personal'' WHERE NOT u.is_external;',
            collisions;
    END IF;
 END $BODY$;
 -- ── Pre-flight 2: report sibling-root distribution (informational) ─────────
 -- Most users have exactly one root (`My Folder - <username>`). Some may
 -- have SQL-added siblings — those become secondary drives. Surface the
@@ -173,16 +220,15 @@ BEGIN
 END $BODY$;
-- ── 2. Insert the drive rows ───────────────────────────────────────────────
+-- ── 2. Insert the drive rows (metadata only — no `name` column) ───────────
-- Default drives carry the i18n-neutral name 'Personal' (renameable
+-- Drives are pure metadata under the new design (docs/plan/drive.md §3).
-- later via the drive settings panel). Secondary drives carry their
+-- The display name lives on the root folder; the wrapper is renamed in
-- original folder name verbatim.
+-- step 4b for default drives and kept as-is for secondaries.
 INSERT INTO storage.drives
-    (id, name, kind, default_for_user, quota_bytes)
+    (id, kind, default_for_user, quota_bytes)
 SELECT
    p.new_drive_id,
    CASE WHEN p.is_default THEN 'Personal' ELSE p.wrapper_name END,
    'personal',
    CASE WHEN p.is_default THEN p.user_id ELSE NULL END,
    p.quota
@@ -199,16 +245,29 @@ SELECT 'user', p.user_id, 'drive', p.new_drive_id, 'owner', p.user_id
 FROM _drive_plan p;
-- ── 4. Stamp drive_id on each wrapper folder ──────────────────────────────
+-- ── 4. Adopt the wrapper as the drive's root folder ───────────────────────
-- The wrapper still exists as a folder during M2 (the wrapper-drop lives
+-- 4a. Stamp drive_id on each wrapper so the cascade in §5 can walk the
-- in M2b). Setting drive_id on the wrapper lets the cascade in §5 walk
+--     ltree subtree without a separate index.
-- the ltree subtree without needing a separate index.
+-- 4b. Rename the default-drive wrapper from `My Folder - <username>` to
 --     `Personal` (the canonical default name; renameable via the folder
 --     API later). The BEFORE-UPDATE folder path trigger fires on the
 --     rename and the AFTER-UPDATE cascade trigger rewrites every
 --     descendant `path` / `lpath` automatically — no per-row UPDATE here.
 -- 4c. Wire drives.root_folder_id to the wrapper. This is the adoption
 --     step: the wrapper row IS the drive's root folder after M2 (no
 --     wrapper-deletion, no descendant promotion).
 UPDATE storage.folders f
-   SET drive_id = p.new_drive_id
+   SET drive_id = p.new_drive_id,
       name     = CASE WHEN p.is_default THEN 'Personal' ELSE f.name END
  FROM _drive_plan p
 WHERE f.id = p.wrapper_id;
 UPDATE storage.drives d
   SET root_folder_id = p.wrapper_id
  FROM _drive_plan p
 WHERE d.id = p.new_drive_id;
 -- ── 5. Cascade drive_id down the folder tree ──────────────────────────────
 -- For every folder descended from a wrapper, set drive_id to that
@@ -284,6 +343,7 @@ DECLARE
    grantless_drives BIGINT;
    null_folder_drive_id BIGINT;
    null_file_drive_id BIGINT;
    rootless_drives BIGINT;
 BEGIN
    SELECT count(*) INTO missing_default
    FROM auth.users u
@@ -320,6 +380,29 @@ BEGIN
            grantless_drives;
    END IF;
    -- Root-folder adoption invariant (docs/plan/drive.md §3): every
    -- drive must point at a real folder row whose drive_id closes the
    -- cycle. The column is NULLable at the type level so the atomic
    -- CTE can write it mid-statement; this check enforces the data
    -- invariant after the migration.
    SELECT count(*) INTO rootless_drives
    FROM storage.drives d
    WHERE d.root_folder_id IS NULL
       OR NOT EXISTS (
           SELECT 1 FROM storage.folders f
            WHERE f.id        = d.root_folder_id
              AND f.drive_id  = d.id
              AND f.parent_id IS NULL
       );
    IF rootless_drives > 0 THEN
        RAISE EXCEPTION
            'D0 backfill consistency check failed: % drive(s) have no '
            'valid root_folder_id (NULL, or pointing at a folder that '
            'isn''t a root in this drive). Investigate before declaring '
            'the migration successful.',
            rootless_drives;
    END IF;
    SELECT count(*) INTO null_folder_drive_id
    FROM storage.folders f
    WHERE f.drive_id IS NULL
@@ -56,6 +56,28 @@ CREATE INDEX IF NOT EXISTS idx_folders_drive_id ON storage.folders (drive_id);
 CREATE INDEX IF NOT EXISTS idx_files_drive_id   ON storage.files   (drive_id);
 -- ── 3b. Drive-scoped folder uniqueness indexes ─────────────────────────────
 -- Pre-D0 the "no duplicate folder name under the same parent for the same
 -- user" constraint was user_id-scoped (docs/plan/drive.md §10). The
 -- semantics users actually want is "no duplicate names *within a drive*"
 -- — a folder named "Reports" in your Personal drive shouldn't preclude
 -- another "Reports" in a shared "Team" drive. Flip the scope here, now
 -- that every row has a drive_id.
 --
 -- Same partial predicate as the originals (NOT is_trashed, plus the
 -- root-vs-non-root split via parent_id IS NULL).
 DROP INDEX IF EXISTS storage.idx_folders_unique_name;
 DROP INDEX IF EXISTS storage.idx_folders_unique_name_root;
 CREATE UNIQUE INDEX IF NOT EXISTS idx_folders_unique_name
    ON storage.folders(parent_id, name, drive_id)
    WHERE NOT is_trashed AND parent_id IS NOT NULL;
 CREATE UNIQUE INDEX IF NOT EXISTS idx_folders_unique_name_root
    ON storage.folders(name, drive_id)
    WHERE NOT is_trashed AND parent_id IS NULL;
 -- ── 4. Post-flight: confirm constraints landed ────────────────────────────
 -- Belt-and-suspenders verification that the NOT NULL + FK actually
 -- exist after the ALTERs above. Any failure here means PostgreSQL
@@ -8,7 +8,8 @@ use serde::{Deserialize, Serialize};
 use utoipa::ToSchema;
 use uuid::Uuid;
-use crate::domain::entities::drive::{Drive, DriveKind};
+use crate::domain::entities::drive::DriveKind;
 use crate::domain::repositories::drive_repository::DriveWithRootName;
 #[derive(Debug, Clone, Copy, Serialize, Deserialize, ToSchema, PartialEq, Eq)]
 #[serde(rename_all = "lowercase")]
@@ -34,12 +35,22 @@ impl From<DriveKind> for DriveKindDto {
 #[derive(Debug, Clone, Serialize, ToSchema)]
 pub struct DriveDto {
    pub id: Uuid,
    /// Display name. Sourced from `storage.folders.name` of the row
    /// pointed at by `root_folder_id` (drives have no `name` column —
    /// see docs/plan/drive.md §3). The wire shape is unchanged from
    /// the client's perspective.
    pub name: String,
    pub kind: DriveKindDto,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub default_for_user: Option<Uuid>,
    /// The drive's mount-point folder. Folder API calls
    /// (`POST /api/folders { parent_id: <root_folder_id> }`,
    /// `PATCH /api/folders/<root_folder_id>` to rename) use this id —
    /// no polymorphic "create at drive root" surface needed.
    pub root_folder_id: Uuid,
    /// Storage cap in bytes. `None` means "no quota" (admin override /
-    /// future system drives).
+    /// future system drives). Mutation is OxiCloud-admin only — drive
    /// owners cannot self-grant capacity.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub quota_bytes: Option<i64>,
    /// Running total of bytes consumed. Maintained incrementally in D4;
@@ -53,18 +64,19 @@ pub struct DriveDto {
    pub updated_at: chrono::DateTime<chrono::Utc>,
 }
-impl From<Drive> for DriveDto {
+impl From<DriveWithRootName> for DriveDto {
-    fn from(d: Drive) -> Self {
+    fn from(d: DriveWithRootName) -> Self {
        Self {
-            id: d.id,
+            id: d.drive.id,
-            name: d.name,
+            name: d.root_folder_name,
-            kind: d.kind.into(),
+            kind: d.drive.kind.into(),
-            default_for_user: d.default_for_user,
+            default_for_user: d.drive.default_for_user,
-            quota_bytes: d.quota_bytes,
+            root_folder_id: d.drive.root_folder_id,
-            used_bytes: d.used_bytes,
+            quota_bytes: d.drive.quota_bytes,
-            policies: d.policies,
+            used_bytes: d.drive.used_bytes,
-            created_at: d.created_at,
+            policies: d.drive.policies,
-            updated_at: d.updated_at,
+            created_at: d.drive.created_at,
            updated_at: d.drive.updated_at,
        }
    }
 }
@@ -36,8 +36,19 @@ pub trait FolderUseCase: Send + Sync + 'static {
        caller_id: Uuid,
    ) -> Result<FolderDto, DomainError>;
-    /// Gets a folder by its path
+    /// Gets a folder by its path within the caller's tree.
-    async fn get_folder_by_path(&self, path: &str) -> Result<FolderDto, DomainError>;
+    ///
    /// Scoped by `user_id` because `storage.folders.path` is unique
    /// only within a single user's drive after D0 — multiple users
    /// share names like `"Personal"` for their default-drive root
    /// folder (docs/plan/drive.md §10). Pre-D0 the wrapper name
    /// embedded the username and made the path globally unique;
    /// post-D0 the caller_id filter is required.
    async fn get_folder_by_path(
        &self,
        path: &str,
        user_id: Uuid,
    ) -> Result<FolderDto, DomainError>;
    /// Lists folders within a parent folder
    async fn list_folders(&self, parent_id: Option<&str>) -> Result<Vec<FolderDto>, DomainError>;
@@ -82,7 +82,11 @@ impl FolderService {
                Ok(FolderDto::empty())
            }
-            async fn get_folder_by_path(&self, _path: &str) -> Result<FolderDto, DomainError> {
+            async fn get_folder_by_path(
                &self,
                _path: &str,
                _user_id: Uuid,
            ) -> Result<FolderDto, DomainError> {
                Ok(FolderDto::empty())
            }
@@ -293,14 +297,17 @@ impl FolderUseCase for FolderService {
        self.get_folder(id).await
    }
-    /// Gets a folder by its path
+    /// Gets a folder by its path, scoped to the caller's tree.
-    async fn get_folder_by_path(&self, path: &str) -> Result<FolderDto, DomainError> {
+    async fn get_folder_by_path(
-        // Convert the string path to StoragePath
+        &self,
        path: &str,
        user_id: Uuid,
    ) -> Result<FolderDto, DomainError> {
        let storage_path = StoragePath::from_string(path);
        let folder = self
            .folder_storage
-            .get_folder_by_path(&storage_path)
+            .get_folder_by_path(&storage_path, user_id)
            .await
            .map_err(|e| {
                DomainError::internal_error(
@@ -766,23 +773,22 @@ use crate::domain::entities::user::User;
 /// when the Owner row is already present.
 pub struct PersonalDriveLifecycleHook {
    drive_repo: Arc<dyn crate::domain::repositories::drive_repository::DriveRepository>,
    folder_service: Arc<FolderService>,
    // The `AuthorizationEngine` trait isn't `dyn`-compatible (native
    // async-fn-in-trait methods are not object-safe), so we hold the
    // concrete engine. This matches the convention already used by
-    // `AppState.authorization`.
+    // `AppState.authorization`. Only the idempotent-rerun path uses it
    // now; the create path goes through the repo's atomic CTE which
    // writes the role_grant inline.
    authorization: Arc<crate::infrastructure::services::pg_acl_engine::PgAclEngine>,
 }
 impl PersonalDriveLifecycleHook {
    pub fn new(
        drive_repo: Arc<dyn crate::domain::repositories::drive_repository::DriveRepository>,
        folder_service: Arc<FolderService>,
        authorization: Arc<crate::infrastructure::services::pg_acl_engine::PgAclEngine>,
    ) -> Self {
        Self {
            drive_repo,
            folder_service,
            authorization,
        }
    }
@@ -792,9 +798,7 @@ impl PersonalDriveLifecycleHook {
    /// trait docstring — they have no resources of their own, only
    /// grants on other users' resources.
    async fn provision_if_needed(&self, user: &User) -> Result<(), DomainError> {
-        use crate::domain::repositories::drive_repository::{
+        use crate::domain::repositories::drive_repository::DriveRepositoryError;
            CreatePersonalDriveInput, DriveRepositoryError,
        };
        use crate::domain::services::authorization::{Resource, Role, Subject};
        if user.is_external() {
@@ -802,20 +806,19 @@ impl PersonalDriveLifecycleHook {
        }
        // Idempotent shortcut: if the user already has a default drive,
-        // nothing to do. Covers re-runs from `on_user_login` plus the
+        // the atomic CTE already ran on a prior turn. The CTE writes
-        // case where `on_user_created` ran successfully but logged in
+        // the Owner role_grant inline, so there's nothing to repair —
-        // before reaching the role_grant step (next-login retry lands
+        // but we still re-emit the grant via `set_role` (UPSERT-safe)
-        // here and finds the drive, completing the role_grant if missing).
+        // to cover the historical case where a pre-CTE provisioning
        // path partially completed (drive created, grant missing).
        match self.drive_repo.find_default_for_user(user.id()).await {
-            Ok(drive) => {
+            Ok(drive_with_name) => {
                // Drive exists; ensure the Owner role_grant is in
                // place too. `set_role` is an UPSERT — safe to re-run.
                self.authorization
                    .set_role(
                        user.id(),
                        Subject::User(user.id()),
                        Role::Owner,
-                        Resource::Drive(drive.id),
+                        Resource::Drive(drive_with_name.drive.id),
                        None,
                    )
                    .await
@@ -831,49 +834,28 @@ impl PersonalDriveLifecycleHook {
            }
        }
-        // Create the drive.
+        // One atomic CTE — drive row + root folder ("Personal",
-        let drive = self
+        // parent_id=NULL, drive_id pinned) + drives.root_folder_id
        // wire-up + Owner role_grant. Single SQL statement, atomic
        // against server crash mid-sequence (docs/plan/drive.md §3).
        let drive_with_name = self
            .drive_repo
-            .create_personal(CreatePersonalDriveInput {
+            .create_personal_drive_atomic(user.id(), Some(user.storage_quota_bytes()))
                name: "Personal".to_owned(),
                owner_id: user.id(),
                is_default: true,
                quota_bytes: Some(user.storage_quota_bytes()),
            })
            .await
            .map_err(|e| {
-                DomainError::internal_error("PersonalDriveHook", format!("create_personal: {e}"))
+                DomainError::internal_error(
-            })?;
+                    "PersonalDriveHook",
-
+                    format!("create_personal_drive_atomic: {e}"),
        // Stamp the Owner role_grant.
        self.authorization
            .set_role(
                user.id(),
                Subject::User(user.id()),
                Role::Owner,
                Resource::Drive(drive.id),
                None,
                )
-            .await
+            })?;
            .map(|_grant| ())?;
        // Provision the wrapper `My Folder - <username>` folder under
        // the new drive. The wrapper is retained through the D0 dual-
        // write window (M2b retires it later); without it, existing API
        // surfaces that assume `GET /api/folders` returns a root folder
        // (the UI listing, the WebDAV resolver, the Hurl baselines) all
        // break for newly-provisioned users.
        self.folder_service
            .ensure_home_folder(user.id(), drive.id, user.username())
            .await
            .map(|_created| ())?;
        tracing::info!(
            target: "user_lifecycle",
            hook = "personal_drive",
            user_id = %user.id(),
-            drive_id = %drive.id,
+            drive_id = %drive_with_name.drive.id,
-            "Default personal drive + wrapper folder provisioned"
+            root_folder_id = %drive_with_name.drive.root_folder_id,
            "Default personal drive + root folder + owner grant provisioned (atomic CTE)"
        );
        Ok(())
    }
@@ -306,7 +306,7 @@ impl SearchService {
            .list_for_subjects(&subject_types, &subject_ids)
            .await
        {
-            Ok(drives) => drives.into_iter().map(|d| d.id).collect(),
+            Ok(drives) => drives.into_iter().map(|d| d.drive.id).collect(),
            Err(e) => {
                tracing::warn!("Content-index: drive lookup failed — degrading to empty: {e}");
                return Vec::new();
@@ -925,6 +925,7 @@ mod tests {
        async fn get_folder_by_path(
            &self,
            _storage_path: &crate::domain::services::path_service::StoragePath,
            _user_id: uuid::Uuid,
        ) -> Result<crate::domain::entities::folder::Folder, DomainError> {
            unimplemented!()
        }
@@ -709,6 +709,7 @@ impl FolderRepository for MockFolderRepository {
    async fn get_folder_by_path(
        &self,
        _storage_path: &StoragePath,
        _user_id: Uuid,
    ) -> std::result::Result<Folder, DomainError> {
        unimplemented!()
    }
@@ -1202,7 +1202,6 @@ impl AppServiceFactory {
                    .with_hook(Arc::new(
                        crate::application::services::folder_service::PersonalDriveLifecycleHook::new(
                            drive_repo.clone(),
                            apps.folder_service_concrete.clone(),
                            authorization.clone(),
                        ),
                    ))
@@ -242,7 +242,11 @@ impl FolderRepository for StubFolderStoragePort {
        Ok(Folder::default())
    }
-    async fn get_folder_by_path(&self, _storage_path: &StoragePath) -> Result<Folder, DomainError> {
+    async fn get_folder_by_path(
        &self,
        _storage_path: &StoragePath,
        _user_id: Uuid,
    ) -> Result<Folder, DomainError> {
        Ok(Folder::default())
    }
@@ -398,7 +402,11 @@ impl FolderUseCase for StubFolderUseCase {
        Ok(FolderDto::default())
    }
-    async fn get_folder_by_path(&self, _path: &str) -> Result<FolderDto, DomainError> {
+    async fn get_folder_by_path(
        &self,
        _path: &str,
        _user_id: Uuid,
    ) -> Result<FolderDto, DomainError> {
        Ok(FolderDto::default())
    }
@@ -76,29 +76,39 @@ impl DriveKind {
 /// Domain entity for a row in `storage.drives`.
 ///
 /// Drives are pure metadata under the D0 design (docs/plan/drive.md §3):
 /// no `name` column — the display name lives on the root folder pointed
 /// at by `root_folder_id`. Code that needs the name pairs this struct
 /// with a JOIN through `storage.folders`; see the repository's
 /// `DriveWithRootName` view-model.
 ///
 /// Field-level constraints are enforced at the SQL layer (CHECK on
 /// `kind`, partial UNIQUE on `default_for_user`). The struct mirrors
 /// the column set 1:1; behaviour beyond field access lives in
-/// `DriveRepository` (D0-5) and `DriveService` (post-D0).
+/// `DriveRepository` and `DriveService` (post-D0).
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Drive {
    /// Stable identifier. Generated server-side at creation.
    pub id: Uuid,
    /// Display name. Renameable by owners; defaults to "Personal" for
    /// the user's default personal drive, or the original sibling-root
    /// folder name for secondaries promoted by the D0 backfill.
    pub name: String,
    /// Discriminant — see [`DriveKind`].
    pub kind: DriveKind,
    /// Set iff this is the user's default personal drive (UNIQUE in SQL
    /// via a partial index `WHERE default_for_user IS NOT NULL`). NULL
    /// on shared drives and on secondary personal drives.
    pub default_for_user: Option<Uuid>,
    /// The drive's mount-point folder. The column is NULLable in SQL
    /// only because the atomic creation CTE writes it mid-statement
    /// (a column-level `NOT NULL` would refuse the initial drive INSERT
    /// — see docs/plan/drive.md §3). After any successful creation path,
    /// this is populated; code reading `Drive` may treat it as `Uuid`,
    /// not `Option<Uuid>`. A NULL at read time is a data-invariant bug.
    pub root_folder_id: Uuid,
    /// Soft cap on this drive's storage usage, in bytes. `None` means
    /// "no quota" (rare; reserved for admin overrides). The default
    /// initial quota for a fresh personal drive is taken from the
-    /// owner's `auth.users.storage_quota_bytes` at creation time (see
+    /// owner's `auth.users.storage_quota_bytes` at creation time.
-    /// Open Question 2 in `docs/plan/drive.md`).
+    /// **Mutation is OxiCloud-admin only** (docs/plan/drive.md §7) —
    /// not in the drive `owner` role bundle.
    pub quota_bytes: Option<i64>,
    /// Running total of bytes consumed. Maintained incrementally by
    /// upload/delete paths in D4; on D0 still reflects the pre-Drive
@@ -37,52 +37,56 @@ pub enum DriveRepositoryError {
    StorageError(String),
 }
-/// Input parameters for creating a new personal drive.
+/// A drive paired with the display name from its root folder.
 ///
-/// Shared drives land in D3 with their own creation surface
+/// `storage.drives` has no `name` column under the D0 design
-/// (`create_shared_drive`). For now D0 only mints personal drives —
+/// (docs/plan/drive.md §3) — the display name lives on
-/// either as the default for a fresh user (via the lifecycle hook) or
+/// `storage.folders.name` of the row pointed at by `drive.root_folder_id`.
-/// as a secondary promoted by the M2 backfill.
+/// Read paths join the two tables and hand callers this view-model so the
-#[derive(Debug, Clone)]
+/// API surface can continue to expose a single "drive with name" shape
-pub struct CreatePersonalDriveInput {
+/// without a follow-up query per drive.
-    /// Display name. The lifecycle hook passes `"Personal"`; the M2
+#[derive(Debug, Clone, PartialEq, Eq)]
-    /// backfill carries over the original sibling-root folder name for
+pub struct DriveWithRootName {
-    /// secondaries.
+    pub drive: Drive,
-    pub name: String,
+    /// The drive's display name. Sourced from `storage.folders.name`
-    /// The owner. For personal drives the owner is exactly one user.
+    /// of the root folder via JOIN at read time.
-    pub owner_id: Uuid,
+    pub root_folder_name: String,
    /// `true` when this is the user's default drive (sets the partial-
    /// unique `default_for_user` column). `false` for secondaries.
    pub is_default: bool,
    /// Initial storage quota in bytes. `None` defers to admin policy
    /// (typically copied from `auth.users.storage_quota_bytes` at the
    /// call site).
    pub quota_bytes: Option<i64>,
 }
 #[async_trait::async_trait]
 pub trait DriveRepository: Send + Sync + 'static {
-    /// Insert a personal drive row. The caller is responsible for
+    /// Atomically create a personal drive together with its root folder
-    /// inserting the matching owner row in `storage.role_grants` in the
+    /// and the owner role_grant — all four DB writes in a single SQL
-    /// same transaction (the lifecycle hook handles this; M2's backfill
+    /// statement (docs/plan/drive.md §3 "Atomic creation"). The
-    /// did it directly in SQL).
+    /// statement runs as its own implicit transaction in autocommit mode
    /// so a server crash mid-statement leaves no half-row state.
    ///
-    /// Returns `DefaultDriveAlreadyExists` when `is_default=true` and the
+    /// The root folder is created with name `"Personal"` (the canonical
-    /// owner already has a default drive — relies on the partial UNIQUE
+    /// default) and `parent_id IS NULL`. The drive's `root_folder_id`
-    /// index on `default_for_user`.
+    /// is wired to point at it before the statement commits.
-    async fn create_personal(
+    ///
    /// Returns `DefaultDriveAlreadyExists` when the owner already has a
    /// default drive — relies on the partial UNIQUE index on
    /// `default_for_user`.
    async fn create_personal_drive_atomic(
        &self,
-        input: CreatePersonalDriveInput,
+        owner_id: Uuid,
-    ) -> Result<Drive, DriveRepositoryError>;
+        quota_bytes: Option<i64>,
    ) -> Result<DriveWithRootName, DriveRepositoryError>;
-    /// Fetch a drive by id. `NotFound` when no row matches.
+    /// Fetch a drive by id together with its display name. `NotFound`
-    async fn get_by_id(&self, id: Uuid) -> Result<Drive, DriveRepositoryError>;
+    /// when no row matches.
    async fn get_by_id(&self, id: Uuid) -> Result<DriveWithRootName, DriveRepositoryError>;
-    /// Return the caller's default personal drive, or `NotFound` if they
+    /// Return the caller's default personal drive paired with its
-    /// don't have one (e.g. external users; users created before the
+    /// display name, or `NotFound` if they don't have one (e.g.
-    /// lifecycle hook fired). Drives the Photos timeline scope, the
+    /// external users; users created before the lifecycle hook fired).
-    /// `/api/recent/*` scope, and D1's redirect-from-`/`.
+    /// Drives the Photos timeline scope, the `/api/recent/*` scope, and
-    async fn find_default_for_user(&self, user_id: Uuid) -> Result<Drive, DriveRepositoryError>;
+    /// D1's redirect-from-`/`.
    async fn find_default_for_user(
        &self,
        user_id: Uuid,
    ) -> Result<DriveWithRootName, DriveRepositoryError>;
    /// List drives the caller can read, resolved via `role_grants` for
    /// `resource_type='drive'`. The caller's group memberships are
@@ -90,13 +94,13 @@ pub trait DriveRepository: Send + Sync + 'static {
    /// is what this method's `subject_ids` argument carries.
    ///
    /// Returns rows in a stable order: default drive first (if any),
-    /// then by name. The `/api/drives` handler relies on that order for
+    /// then by display name. The `/api/drives` handler relies on that
-    /// the picker UI without a follow-up sort.
+    /// order for the picker UI without a follow-up sort.
    async fn list_for_subjects(
        &self,
        subject_types: &[&str],
        subject_ids: &[Uuid],
-    ) -> Result<Vec<Drive>, DriveRepositoryError>;
+    ) -> Result<Vec<DriveWithRootName>, DriveRepositoryError>;
 }
 /// Convenience: convert the canonical kind discriminator from its SQL
@@ -28,8 +28,18 @@ pub trait FolderRepository: Send + Sync + 'static {
    /// Gets a folder by its ID
    async fn get_folder(&self, id: &str) -> Result<Folder, DomainError>;
-    /// Gets a folder by its storage path
+    /// Gets a folder by its storage path within the caller's tree.
-    async fn get_folder_by_path(&self, storage_path: &StoragePath) -> Result<Folder, DomainError>;
+    ///
    /// Post-D0, `storage.folders.path` is no longer globally unique —
    /// multiple users share root-folder names like `"Personal"`. The
    /// `user_id` filter scopes the lookup to the caller's own folders
    /// (the equivalent of the pre-D0 implicit user-namespacing that
    /// came from `My Folder - <username>` paths).
    async fn get_folder_by_path(
        &self,
        storage_path: &StoragePath,
        user_id: Uuid,
    ) -> Result<Folder, DomainError>;
    /// Lists folders within a parent folder
    async fn list_folders(&self, parent_id: Option<&str>) -> Result<Vec<Folder>, DomainError>;
@@ -15,7 +15,7 @@ use sqlx::{PgPool, Row, types::Uuid};
 use crate::domain::entities::drive::{Drive, DriveKind};
 use crate::domain::repositories::drive_repository::{
-    CreatePersonalDriveInput, DriveRepository, DriveRepositoryError,
+    DriveRepository, DriveRepositoryError, DriveWithRootName,
 };
 pub struct DrivePgRepository {
@@ -35,67 +35,159 @@ impl DrivePgRepository {
            // unique_violation. With drives, the only relevant unique is
            // the partial index `idx_drives_default_for_user_unique` —
            // surface the typed variant so the lifecycle hook can detect
-            // idempotent re-runs (D0-9 calls create_personal during
+            // idempotent re-runs (D0-9 calls create_personal_drive_atomic
-            // user provisioning).
+            // during user provisioning).
            return DriveRepositoryError::DefaultDriveAlreadyExists(dberr.to_string());
        }
        DriveRepositoryError::StorageError(format!("{context}: {e}"))
    }
-    fn row_to_drive(row: &sqlx::postgres::PgRow) -> Result<Drive, DriveRepositoryError> {
+    /// Map a row carrying both the drive's columns AND a `root_folder_name`
    /// column (sourced via JOIN with `storage.folders`) into the view-model.
    fn row_to_drive_with_name(
        row: &sqlx::postgres::PgRow,
    ) -> Result<DriveWithRootName, DriveRepositoryError> {
        let kind_str: String = row.get("kind");
        let kind = DriveKind::from_sql(&kind_str)?;
-        Ok(Drive {
+        let drive = Drive {
            id: row.get("id"),
            name: row.get("name"),
            kind,
            default_for_user: row.get("default_for_user"),
            root_folder_id: row.get("root_folder_id"),
            quota_bytes: row.get("quota_bytes"),
            used_bytes: row.get("used_bytes"),
            policies: row.get("policies"),
            created_at: row.get("created_at"),
            updated_at: row.get("updated_at"),
        };
        Ok(DriveWithRootName {
            drive,
            root_folder_name: row.get("root_folder_name"),
        })
    }
 }
 #[async_trait::async_trait]
 impl DriveRepository for DrivePgRepository {
-    async fn create_personal(
+    async fn create_personal_drive_atomic(
        &self,
-        input: CreatePersonalDriveInput,
+        owner_id: Uuid,
-    ) -> Result<Drive, DriveRepositoryError> {
+        quota_bytes: Option<i64>,
-        let default_for_user = if input.is_default {
+    ) -> Result<DriveWithRootName, DriveRepositoryError> {
-            Some(input.owner_id)
+        // Four writes wrapped in a single transaction so either all
-        } else {
+        // commit or none does (docs/plan/drive.md §3). A single CTE
-            None
+        // statement would be cleaner on paper but doesn't work in
-        };
+        // PostgreSQL: CTE sub-statements share an MVCC snapshot, so
-        let row = sqlx::query(
+        // `UPDATE storage.drives WHERE id = …` cannot match a row
        // inserted by an earlier CTE branch. We use plain sequential
        // statements inside `pool.begin()` instead — each statement
        // sees the prior ones' writes (transaction-local visibility),
        // and FK constraints are satisfied at insert time because the
        // referenced rows already exist.
        //
        // Rollback semantics: any error before `tx.commit()` (FK
        // violation, unique_violation on `default_for_user`, server
        // crash) discards every partial write. No orphan drive, no
        // folder without a drive, no drive without an owner.
        let mut tx = self
            .pool
            .begin()
            .await
            .map_err(|e| Self::map_sqlx_err("create_personal_drive_atomic.begin", e))?;
        // 1. Drive row (root_folder_id NULL — populated in step 3).
        let drive_id: Uuid = sqlx::query_scalar(
            r#"
            INSERT INTO storage.drives
-                (name, kind, default_for_user, quota_bytes, policies)
+                (kind, default_for_user, quota_bytes, policies)
-            VALUES ($1, 'personal', $2, $3, '{}'::jsonb)
+            VALUES ('personal', $1, $2, '{}'::jsonb)
-            RETURNING id, name, kind, default_for_user, quota_bytes,
+            RETURNING id
                      used_bytes, policies, created_at, updated_at
            "#,
        )
-        .bind(&input.name)
+        .bind(owner_id)
-        .bind(default_for_user)
+        .bind(quota_bytes)
-        .bind(input.quota_bytes)
+        .fetch_one(&mut *tx)
        .fetch_one(self.pool.as_ref())
        .await
-        .map_err(|e| Self::map_sqlx_err("create_personal", e))?;
+        .map_err(|e| Self::map_sqlx_err("create_personal_drive_atomic.drive", e))?;
-        Self::row_to_drive(&row)
+        // 2. Root folder. `parent_id IS NULL` makes it a root in the
-    }
+        //    drive; `drive_id` closes the FK in this direction.
        let folder_id: Uuid = sqlx::query_scalar(
            r#"
            INSERT INTO storage.folders
                (name, parent_id, user_id, drive_id, created_by, updated_by)
            VALUES ('Personal', NULL, $1, $2, $1, $1)
            RETURNING id
            "#,
        )
        .bind(owner_id)
        .bind(drive_id)
        .fetch_one(&mut *tx)
        .await
        .map_err(|e| Self::map_sqlx_err("create_personal_drive_atomic.folder", e))?;
-    async fn get_by_id(&self, id: Uuid) -> Result<Drive, DriveRepositoryError> {
+        // 3. Close the other side of the circular reference.
        sqlx::query(
            r#"UPDATE storage.drives SET root_folder_id = $1 WHERE id = $2"#,
        )
        .bind(folder_id)
        .bind(drive_id)
        .execute(&mut *tx)
        .await
        .map_err(|e| Self::map_sqlx_err("create_personal_drive_atomic.wire", e))?;
        // 4. Owner role_grant — the caller becomes the drive's sole
        //    owner (single-user invariant on personal drives, §2).
        sqlx::query(
            r#"
            INSERT INTO storage.role_grants
                (subject_type, subject_id, resource_type, resource_id,
                 role, granted_by)
            VALUES ('user', $1, 'drive', $2, 'owner', $1)
            "#,
        )
        .bind(owner_id)
        .bind(drive_id)
        .execute(&mut *tx)
        .await
        .map_err(|e| Self::map_sqlx_err("create_personal_drive_atomic.grant", e))?;
        // Fetch the row in its final state so the caller gets a
        // consistent view (including DB-computed defaults like
        // `created_at`, `used_bytes`).
        let row = sqlx::query(
            r#"
-            SELECT id, name, kind, default_for_user, quota_bytes,
+            SELECT d.id, d.kind, d.default_for_user, d.root_folder_id,
-                   used_bytes, policies, created_at, updated_at
+                   d.quota_bytes, d.used_bytes, d.policies,
-              FROM storage.drives
+                   d.created_at, d.updated_at,
-             WHERE id = $1
+                   f.name AS root_folder_name
              FROM storage.drives d
              JOIN storage.folders f ON f.id = d.root_folder_id
             WHERE d.id = $1
            "#,
        )
        .bind(drive_id)
        .fetch_one(&mut *tx)
        .await
        .map_err(|e| Self::map_sqlx_err("create_personal_drive_atomic.read", e))?;
        tx.commit()
            .await
            .map_err(|e| Self::map_sqlx_err("create_personal_drive_atomic.commit", e))?;
        Self::row_to_drive_with_name(&row)
    }
    async fn get_by_id(&self, id: Uuid) -> Result<DriveWithRootName, DriveRepositoryError> {
        let row = sqlx::query(
            r#"
            SELECT d.id, d.kind, d.default_for_user, d.root_folder_id,
                   d.quota_bytes, d.used_bytes, d.policies,
                   d.created_at, d.updated_at,
                   f.name AS root_folder_name
              FROM storage.drives d
              JOIN storage.folders f ON f.id = d.root_folder_id
             WHERE d.id = $1
            "#,
        )
        .bind(id)
@@ -104,16 +196,22 @@ impl DriveRepository for DrivePgRepository {
        .map_err(|e| Self::map_sqlx_err("get_by_id", e))?
        .ok_or_else(|| DriveRepositoryError::NotFound(id.to_string()))?;
-        Self::row_to_drive(&row)
+        Self::row_to_drive_with_name(&row)
    }
-    async fn find_default_for_user(&self, user_id: Uuid) -> Result<Drive, DriveRepositoryError> {
+    async fn find_default_for_user(
        &self,
        user_id: Uuid,
    ) -> Result<DriveWithRootName, DriveRepositoryError> {
        let row = sqlx::query(
            r#"
-            SELECT id, name, kind, default_for_user, quota_bytes,
+            SELECT d.id, d.kind, d.default_for_user, d.root_folder_id,
-                   used_bytes, policies, created_at, updated_at
+                   d.quota_bytes, d.used_bytes, d.policies,
-              FROM storage.drives
+                   d.created_at, d.updated_at,
-             WHERE default_for_user = $1
+                   f.name AS root_folder_name
              FROM storage.drives d
              JOIN storage.folders f ON f.id = d.root_folder_id
             WHERE d.default_for_user = $1
            "#,
        )
        .bind(user_id)
@@ -122,39 +220,41 @@ impl DriveRepository for DrivePgRepository {
        .map_err(|e| Self::map_sqlx_err("find_default_for_user", e))?
        .ok_or_else(|| DriveRepositoryError::NotFound(user_id.to_string()))?;
-        Self::row_to_drive(&row)
+        Self::row_to_drive_with_name(&row)
    }
    async fn list_for_subjects(
        &self,
        subject_types: &[&str],
        subject_ids: &[Uuid],
-    ) -> Result<Vec<Drive>, DriveRepositoryError> {
+    ) -> Result<Vec<DriveWithRootName>, DriveRepositoryError> {
-        // Joining `role_grants` → `storage.drives` returns every drive
+        // Joining role_grants → drives → folders returns every drive the
-        // the expanded subject set can read. ORDER BY puts default
+        // expanded subject set can read, paired with its display name.
-        // drives first (so the picker UI doesn't need a follow-up
+        // ORDER BY puts default drives first (so the picker UI doesn't
-        // sort), then alphabetical by name. DISTINCT collapses the
+        // need a follow-up sort), then alphabetical by name. GROUP BY
-        // case where a caller has multiple role_grants on the same
+        // collapses duplicate role_grants on the same drive (direct +
-        // drive (e.g. direct + group-mediated); a GROUP BY on the
+        // group-mediated) and sidesteps PostgreSQL's "ORDER BY
-        // drive id sidesteps PostgreSQL's "ORDER BY expression must
+        // expression must appear in select list" rule that SELECT
-        // appear in select list" rule that `SELECT DISTINCT` imposes.
+        // DISTINCT imposes.
        let rows = sqlx::query(
            r#"
-            SELECT d.id, d.name, d.kind, d.default_for_user,
+            SELECT d.id, d.kind, d.default_for_user, d.root_folder_id,
                   d.quota_bytes, d.used_bytes, d.policies,
-                   d.created_at, d.updated_at
+                   d.created_at, d.updated_at,
                   f.name AS root_folder_name
              FROM storage.drives d
              JOIN storage.folders f ON f.id = d.root_folder_id
              JOIN storage.role_grants g
                ON g.resource_type = 'drive'
               AND g.resource_id   = d.id
             WHERE g.subject_type = ANY($1)
               AND g.subject_id   = ANY($2)
               AND (g.expires_at IS NULL OR g.expires_at > NOW())
-             GROUP BY d.id, d.name, d.kind, d.default_for_user,
+             GROUP BY d.id, d.kind, d.default_for_user, d.root_folder_id,
                      d.quota_bytes, d.used_bytes, d.policies,
-                      d.created_at, d.updated_at
+                      d.created_at, d.updated_at, f.name
             ORDER BY (d.default_for_user IS NULL) ASC,
-                      LOWER(d.name) ASC
+                      LOWER(f.name) ASC
            "#,
        )
        .bind(
@@ -168,6 +268,6 @@ impl DriveRepository for DrivePgRepository {
        .await
        .map_err(|e| Self::map_sqlx_err("list_for_subjects", e))?;
-        rows.iter().map(Self::row_to_drive).collect()
+        rows.iter().map(Self::row_to_drive_with_name).collect()
    }
 }
@@ -236,7 +236,11 @@ impl FolderRepository for FolderDbRepository {
        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> {
+    async fn get_folder_by_path(
        &self,
        storage_path: &StoragePath,
        user_id: Uuid,
    ) -> Result<Folder, DomainError> {
        let path_str = storage_path.to_string();
        // Strip leading '/' if present — DB stores "Home - user/Docs", not "/Home - user/Docs"
        let lookup = path_str.strip_prefix('/').unwrap_or(&path_str);
@@ -245,6 +249,13 @@ impl FolderRepository for FolderDbRepository {
            return Err(DomainError::not_found("Folder", "empty path"));
        }
        // Scoped by user_id: post-D0 the wrapper folder is named
        // "Personal" for every user, so `path = 'Personal'` matches
        // every user's root folder. Without the user_id filter, this
        // returns a non-deterministic row (whichever the planner emits
        // first) — which broke owner-short-circuit checks for the
        // caller whose folder wasn't returned. See bug-fix on rewind
        // commit.
        let row = sqlx::query_as::<_, FolderRow>(
            r#"
            SELECT id::text, name, path, parent_id::text, user_id,
@@ -252,10 +263,11 @@ impl FolderRepository for FolderDbRepository {
                   EXTRACT(EPOCH FROM updated_at)::bigint,
                       EXTRACT(EPOCH FROM tree_modified_at)::bigint
              FROM storage.folders
-             WHERE path = $1 AND NOT is_trashed
+             WHERE path = $1 AND user_id = $2 AND NOT is_trashed
            "#,
        )
        .bind(lookup)
        .bind(user_id)
        .fetch_optional(self.pool())
        .await
        .map_err(|e| DomainError::internal_error("FolderDb", format!("path lookup: {e}")))?
@@ -469,7 +469,7 @@ async fn handle_propfind(
        }
    } else {
        // Fallback: legacy double-query path when PathResolver is unavailable
-        if let Ok(folder) = folder_service.get_folder_by_path(&path).await {
+        if let Ok(folder) = folder_service.get_folder_by_path(&path, user.id).await {
            assert_owner(folder.owner_id.as_deref(), &user.id.to_string(), &path)?;
            let folder_id = folder.id.clone();
            return build_streaming_propfind_response(
@@ -656,7 +656,7 @@ async fn handle_proppatch(
    req: Request<Body>,
    path: String,
 ) -> Result<Response<Body>, AppError> {
-    let _user = extract_user(&req)?;
+    let user = extract_user(&req)?;
    // Active-lock guard (RFC 4918 §9.10.4): PROPPATCH writes properties,
    // so a lock on the target must release them via `If:`. Captured
@@ -691,7 +691,7 @@ async fn handle_proppatch(
        state
            .applications
            .folder_service
-            .get_folder_by_path(&path)
+            .get_folder_by_path(&path, user.id)
            .await
            .is_ok()
    };
@@ -877,7 +877,7 @@ async fn handle_head(
    }
    // Fallback: legacy double-query path (with ownership check)
-    if let Ok(folder) = folder_service.get_folder_by_path(&path).await {
+    if let Ok(folder) = folder_service.get_folder_by_path(&path, user.id).await {
        assert_owner(folder.owner_id.as_deref(), &user.id.to_string(), &path)?;
        return Ok(Response::builder()
            .status(StatusCode::OK)
@@ -941,7 +941,7 @@ async fn resolve_or_legacy(
    let user_id_str = user_id.to_string();
    let folder_service = &state.applications.folder_service;
-    if let Ok(folder) = folder_service.get_folder_by_path(path).await
+    if let Ok(folder) = folder_service.get_folder_by_path(path, user_id).await
        && folder.owner_id.as_deref() == Some(&user_id_str)
    {
        return Some(ResolvedResource::Folder(folder));
@@ -1208,7 +1208,7 @@ async fn handle_mkcol(
        }
        accumulated_path.push_str(segment);
-        match folder_service.get_folder_by_path(&accumulated_path).await {
+        match folder_service.get_folder_by_path(&accumulated_path, user.id).await {
            Ok(existing) => {
                parent_id = Some(existing.id);
            }
@@ -1401,7 +1401,7 @@ async fn handle_move(
                .unwrap_or(false)
        } else {
            folder_service
-                .get_folder_by_path(&destination_path)
+                .get_folder_by_path(&destination_path, user.id)
                .await
                .is_ok()
                || file_retrieval_service
@@ -1443,7 +1443,7 @@ async fn handle_move(
            let move_dto = crate::application::dtos::folder_dto::MoveFolderDto {
                parent_id: if dest_parent_path.is_empty() {
                    None
-                } else if let Ok(parent) = folder_service.get_folder_by_path(dest_parent_path).await
+                } else if let Ok(parent) = folder_service.get_folder_by_path(dest_parent_path, user.id).await
                {
                    assert_owner(
                        parent.owner_id.as_deref(),
@@ -1483,7 +1483,7 @@ async fn handle_move(
                    None
                } else {
                    let parent = folder_service
-                        .get_folder_by_path(dest_parent_path)
+                        .get_folder_by_path(dest_parent_path, user.id)
                        .await
                        .map_err(|_| {
                            AppError::not_found(format!(
@@ -1610,7 +1610,7 @@ async fn handle_copy(
                .unwrap_or(false)
        } else {
            folder_service
-                .get_folder_by_path(&destination_path)
+                .get_folder_by_path(&destination_path, user.id)
                .await
                .is_ok()
                || file_retrieval_service
@@ -1644,7 +1644,7 @@ async fn handle_copy(
    let target_parent_id = if dest_parent_path.is_empty() {
        None
-    } else if let Ok(parent) = folder_service.get_folder_by_path(dest_parent_path).await {
+    } else if let Ok(parent) = folder_service.get_folder_by_path(dest_parent_path, user.id).await {
        assert_owner(
            parent.owner_id.as_deref(),
            &user.id.to_string(),
@@ -1743,7 +1743,7 @@ async fn handle_lock(
        state
            .applications
            .folder_service
-            .get_folder_by_path(&path)
+            .get_folder_by_path(&path, user.id)
            .await
            .is_ok()
    };
@@ -399,10 +399,14 @@ pub async fn handle_search(
    let mut entries: Vec<serde_json::Value> = Vec::new();
    // Map file results
    // TODO(D1): drop the hardcoded "Personal/" prefix and read the
    // caller's default-drive root folder name from `drives.root_folder_id`
    // instead. Correct for D0-provisioned default drives; secondary
    // drives keep their original root name.
    for file in &results.files {
        let display_path = file
            .path
-            .strip_prefix(&format!("My Folder - {}/", user.username))
+            .strip_prefix("Personal/")
            .unwrap_or(&file.path);
        let display_path = format!("/{}", display_path);
@@ -427,11 +431,11 @@ pub async fn handle_search(
        }));
    }
-    // Map folder results
+    // Map folder results — same TODO(D1) as above.
    for folder in &results.folders {
        let display_path = folder
            .path
-            .strip_prefix(&format!("My Folder - {}/", user.username))
+            .strip_prefix("Personal/")
            .unwrap_or(&folder.path);
        let display_path = format!("/{}", display_path);
@@ -83,7 +83,11 @@ async fn handle_filter_files(
    // All items in this response are favorites.
    let favorite_ids: HashSet<String> = favorites.iter().map(|f| f.item_id.clone()).collect();
-    let home_prefix = format!("My Folder - {}/", user.username);
+    // TODO(D1): replace the hardcoded "Personal/" prefix with the
    // caller's default-drive root folder name read from
    // `drives.root_folder_id`. Correct for D0-provisioned default
    // drives; secondary drives keep their original root name.
    let home_prefix = "Personal/";
    // Pass 1: resolve the favorited DTOs in two batch queries (was one
    // get_* per favorite — up to N serial round-trips on a sync client's
@@ -146,7 +150,7 @@ async fn handle_filter_files(
        write_multistatus_start(&mut xml)?;
        for file in &files {
-            let subpath = strip_home_prefix(&file.path, &home_prefix);
+            let subpath = strip_home_prefix(&file.path, home_prefix);
            let href = nc_href(&user.username, subpath);
            let fid = file_id_map.get(&file.id).copied();
            let oc_id = fid.map(|id| format_oc_id(id, file_id_svc));
@@ -163,7 +167,7 @@ async fn handle_filter_files(
        }
        for folder in &folders {
-            let subpath = strip_home_prefix(&folder.path, &home_prefix);
+            let subpath = strip_home_prefix(&folder.path, home_prefix);
            let href = format!("{}/", nc_href(&user.username, subpath));
            let fid = folder_id_map.get(&folder.id).copied();
            let oc_id = fid.map(|id| format_oc_id(id, file_id_svc));
@@ -210,7 +214,7 @@ async fn handle_search(
    let nresults = parse_nresults(body).unwrap_or(100);
    // Resolve folder scope from <d:href> inside <d:scope>.
-    let folder_id = resolve_scope_folder(&state, body, &user.username).await;
+    let folder_id = resolve_scope_folder(&state, body, &user.username, user.id).await;
    let criteria = SearchCriteriaDto {
        name_contains: Some(term),
@@ -227,7 +231,10 @@ async fn handle_search(
    let nc = state.nextcloud.as_ref();
    let file_id_svc = nc.map(|n| &n.file_ids);
-    let home_prefix = format!("My Folder - {}/", user.username);
+    // TODO(D1): same as the favorites pass above — replace the
    // hardcoded "Personal/" with the caller's actual default-drive
    // root folder name from `drives.root_folder_id`.
    let home_prefix = "Personal/";
    // No favorite checking for search results -- pass an empty set.
    let favorite_ids: HashSet<String> = HashSet::new();
@@ -249,7 +256,7 @@ async fn handle_search(
        // Files.
        for file in &files {
-            let subpath = strip_home_prefix(&file.path, &home_prefix);
+            let subpath = strip_home_prefix(&file.path, home_prefix);
            let href = nc_href(&user.username, subpath);
            let fid = file_id_map.get(&file.id).copied();
            let oc_id = fid.map(|id| format_oc_id(id, file_id_svc));
@@ -267,7 +274,7 @@ async fn handle_search(
        // Folders.
        for folder in &folders {
-            let subpath = strip_home_prefix(&folder.path, &home_prefix);
+            let subpath = strip_home_prefix(&folder.path, home_prefix);
            let href = format!("{}/", nc_href(&user.username, subpath));
            let fid = folder_id_map.get(&folder.id).copied();
            let oc_id = fid.map(|id| format_oc_id(id, file_id_svc));
@@ -461,7 +468,12 @@ fn xml_extract_text(body: &str, local_name: &[u8]) -> Option<String> {
 }
 /// Resolve a scope href (e.g. `/files/username/Documents`) to a folder ID.
-async fn resolve_scope_folder(state: &AppState, body: &str, username: &str) -> Option<String> {
+async fn resolve_scope_folder(
    state: &AppState,
    body: &str,
    username: &str,
    user_id: uuid::Uuid,
 ) -> Option<String> {
    let href = parse_scope_href(body)?;
    // The href is typically `/files/{user}/subpath` or `/remote.php/dav/files/{user}/subpath`.
@@ -477,7 +489,7 @@ async fn resolve_scope_folder(state: &AppState, body: &str, username: &str) -> O
    let folder_service = &state.applications.folder_service;
    folder_service
-        .get_folder_by_path(&internal_path)
+        .get_folder_by_path(&internal_path, user_id)
        .await
        .ok()
        .map(|f| f.id)
@@ -133,7 +133,7 @@ async fn handle_restore(
        let file_service = &state.applications.file_retrieval_service;
        let dest_taken = file_service.get_file_by_path(&dest_internal).await.is_ok()
            || folder_service
-                .get_folder_by_path(&dest_internal)
+                .get_folder_by_path(&dest_internal, user.id)
                .await
                .is_ok();
        if dest_taken {
@@ -248,11 +248,18 @@ fn mime_from_name(name: &str) -> String {
        .to_string()
 }
-/// Strip the "My Folder - {username}/" prefix from an original path to produce
+/// Strip the home-folder prefix from an original path to produce the
-/// the Nextcloud-relative original location.
+/// Nextcloud-relative original location.
-fn strip_home_prefix<'a>(original_path: &'a str, username: &str) -> &'a str {
+///
-    let prefix = format!("My Folder - {}/", username);
+/// TODO(D1): replace the hardcoded "Personal/" with the caller's actual
-    original_path.strip_prefix(&prefix).unwrap_or(original_path)
+/// default-drive root folder name read from `drives.root_folder_id`.
 /// Correct for D0-provisioned default drives; secondary drives keep
 /// their original root name. The `_username` arg stays for now so the
 /// upcoming dynamic lookup has a way to identify the caller.
 fn strip_home_prefix<'a>(original_path: &'a str, _username: &str) -> &'a str {
    original_path
        .strip_prefix("Personal/")
        .unwrap_or(original_path)
 }
 // ────────────── Trashbin PROPFIND XML Generation ──────────────
@@ -256,11 +256,12 @@ async fn handle_assemble(
    let file_service = &state.applications.file_retrieval_service;
    let folder_service = &state.applications.folder_service;
-    let internal_path = format!(
+    // TODO(D1): read the caller's default-drive root folder name from
-        "My Folder - {}/{}",
+    // `drives.root_folder_id` instead of hardcoding "Personal". The
-        user.username,
+    // constant is correct for every default personal drive provisioned
-        dest_subpath.trim_matches('/')
+    // by the D0 lifecycle hook, but secondary drives (M2 backfill from
-    );
+    // SQL-created sibling root folders) keep their original name.
    let internal_path = format!("Personal/{}", dest_subpath.trim_matches('/'));
    let filename = filename_from_path(&dest_subpath).to_string();
    let ingested = ingest_stream_to_cas(
@@ -291,15 +292,11 @@ async fn handle_assemble(
            Some((p, n)) => (p, n),
            None => ("", dest_subpath.as_str()),
        };
-        let parent_internal = format!(
+        let parent_internal = format!("Personal/{}", parent_sub.trim_matches('/'));
            "My Folder - {}/{}",
            user.username,
            parent_sub.trim_matches('/')
        );
        let parent_internal = parent_internal.trim_end_matches('/');
        use crate::application::ports::folder_ports::FolderUseCase;
-        let parent_folder = match folder_service.get_folder_by_path(parent_internal).await {
+        let parent_folder = match folder_service.get_folder_by_path(parent_internal, user.id).await {
            Ok(folder) => folder,
            Err(e) => {
                discard_ingested(&state.core.dedup_service, &ingested).await;
@@ -53,8 +53,15 @@ const HEADER_DAV: HeaderName = HeaderName::from_static("dav");
 /// Internal:  My Folder - {username}/{subpath}
 ///
 /// An empty subpath maps to the user's home folder root.
-pub fn nc_to_internal_path(username: &str, subpath: &str) -> Result<String, AppError> {
+pub fn nc_to_internal_path(_username: &str, subpath: &str) -> Result<String, AppError> {
-    let home = format!("My Folder - {}", username);
+    // D0: every default personal drive's root folder is named "Personal"
    // (docs/plan/drive.md §3 — the canonical post-D0 default). The NC
    // dispatcher chroots into the caller's default drive, so the leading
    // segment of the internal path is always the drive's root folder
    // name. Hardcoded for now; a follow-up will read it from
    // `drives.root_folder_id`'s name to support secondary drives with
    // custom root-folder names.
    let home = "Personal".to_string();
    let subpath = subpath.trim_matches('/');
    if subpath.is_empty() {
        return Ok(home);
@@ -203,7 +210,7 @@ async fn handle_propfind(
    let file_service = &state.applications.file_retrieval_service;
    // Try to resolve as folder first.
-    let folder_result = folder_service.get_folder_by_path(&internal_path).await;
+    let folder_result = folder_service.get_folder_by_path(&internal_path, user.id).await;
    if let Ok(folder) = folder_result {
        // It's a folder — stream the multistatus: children are fetched in
@@ -281,7 +288,7 @@ async fn handle_get(
    // Check if path is a folder first (NC clients use GET as existence check)
    if folder_service
-        .get_folder_by_path(&internal_path)
+        .get_folder_by_path(&internal_path, user.id)
        .await
        .is_ok()
    {
@@ -358,7 +365,7 @@ async fn handle_head(
    // Check if path is a folder (NC clients use HEAD as existence check)
    if folder_service
-        .get_folder_by_path(&internal_path)
+        .get_folder_by_path(&internal_path, user.id)
        .await
        .is_ok()
    {
@@ -433,7 +440,7 @@ async fn handle_proppatch(
    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 {
+    } else if let Ok(folder) = folder_service.get_folder_by_path(&internal_path, user.id).await {
        Some((folder.id, "folder"))
    } else {
        None
@@ -733,7 +740,7 @@ async fn handle_mkcol(
    // auto-create doesn't break real clients.
    if folder_service
-        .get_folder_by_path(&internal_path)
+        .get_folder_by_path(&internal_path, user.id)
        .await
        .is_ok()
    {
@@ -758,7 +765,7 @@ async fn handle_mkcol(
        format!("{}/{}", user_root, parent_segments.join("/"))
    };
-    let parent_folder = match folder_service.get_folder_by_path(&parent_path).await {
+    let parent_folder = match folder_service.get_folder_by_path(&parent_path, user.id).await {
        Ok(folder) => folder,
        Err(_) => {
            return Ok(Response::builder()
@@ -797,7 +804,7 @@ async fn handle_delete(
    // Prefer soft-delete (move to trash) when trash service is available.
    // This is what Nextcloud clients expect — items appear in the trashbin.
    if let Some(trash_svc) = state.trash_service.as_ref() {
-        if let Ok(folder) = folder_service.get_folder_by_path(&internal_path).await {
+        if let Ok(folder) = folder_service.get_folder_by_path(&internal_path, user.id).await {
            trash_svc
                .move_to_trash(&folder.id, "folder", user.id)
                .await
@@ -823,7 +830,7 @@ async fn handle_delete(
    // Fallback: hard delete when trash service is not available.
    let file_mgmt = &state.applications.file_management_service;
-    if let Ok(folder) = folder_service.get_folder_by_path(&internal_path).await {
+    if let Ok(folder) = folder_service.get_folder_by_path(&internal_path, user.id).await {
        folder_service
            .delete_folder_with_perms(&folder.id, user.id)
            .await
@@ -897,7 +904,7 @@ async fn handle_move(
        .await
        .ok();
    let dest_existing_folder = folder_service
-        .get_folder_by_path(&dest_internal_precheck)
+        .get_folder_by_path(&dest_internal_precheck, user.id)
        .await
        .ok();
    let dest_existed_before = dest_existing_file.is_some() || dest_existing_folder.is_some();
@@ -962,7 +969,7 @@ async fn handle_move(
        } else {
            // Different parent → move.
            let dest_parent = folder_service
-                .get_folder_by_path(&dest_parent_internal)
+                .get_folder_by_path(&dest_parent_internal, user.id)
                .await
                .map_err(|_| AppError::not_found("Destination folder not found"))?;
@@ -997,7 +1004,7 @@ async fn handle_move(
    }
    // Try as folder.
-    if let Ok(folder) = folder_service.get_folder_by_path(&src_internal).await {
+    if let Ok(folder) = folder_service.get_folder_by_path(&src_internal, user.id).await {
        let (dest_parent_sub, dest_name) = match dest_subpath.rsplit_once('/') {
            Some((parent, name)) => (parent, name),
            None => ("", dest_subpath.as_str()),
@@ -1025,7 +1032,7 @@ async fn handle_move(
        } else {
            // Different parent → move.
            let dest_parent = folder_service
-                .get_folder_by_path(&dest_parent_internal)
+                .get_folder_by_path(&dest_parent_internal, user.id)
                .await
                .map_err(|_| AppError::not_found("Destination parent not found"))?;
@@ -48,8 +48,14 @@ jsonpath "$" count >= 1
 jsonpath "$[0].kind"             == "personal"
 jsonpath "$[0].default_for_user" == "{{admin_user_id}}"
 jsonpath "$[0].name"             == "Personal"
 # root_folder_id surfaces the drive's mount-point folder. Sourced via
 # JOIN from storage.folders.name — drives have no `name` column under
 # the D0 design (docs/plan/drive.md §3). Folder API operations
 # (create-in-drive, rename-drive) all key off this id.
 jsonpath "$[0].root_folder_id"   exists
 [Captures]
 admin_drive_id: jsonpath "$[0].id"
 admin_root_folder_id: jsonpath "$[0].root_folder_id"
 # ─────────────────────────────────────────────────────────────
@@ -110,6 +116,8 @@ HTTP 200
 jsonpath "$" count == 1
 jsonpath "$[0].kind"             == "personal"
 jsonpath "$[0].default_for_user" == "{{alice_user_id}}"
 jsonpath "$[0].name"             == "Personal"
 jsonpath "$[0].root_folder_id"   exists
 [Captures]
 alice_drive_id: jsonpath "$[0].id"
@@ -122,6 +130,8 @@ HTTP 200
 jsonpath "$" count == 1
 jsonpath "$[0].kind"             == "personal"
 jsonpath "$[0].default_for_user" == "{{bob_user_id}}"
 jsonpath "$[0].name"             == "Personal"
 jsonpath "$[0].root_folder_id"   exists
 [Captures]
 bob_drive_id: jsonpath "$[0].id"
@@ -281,12 +281,16 @@ jsonpath "$.items[*].resource.name" not contains "bob-attack-2"
 # WebDAV MKCOL — namespace isolation
 # ═════════════════════════════════════════════════════════════
 # WebDAV requests are isolated per-user by `resolve_webdav_path`
-# (webdav_handler.rs:189). If the requested path doesn't begin
+# (webdav_handler.rs:235). If the requested path doesn't begin
-# with the caller's home folder name ("My Folder - <username>"),
+# with the caller's home folder name (the drive's root folder
-# the handler silently prefixes the caller's home folder path
+# name — "Personal" by default post-D0), the handler silently
-# onto the front. Effect: any WebDAV path a client sends is
+# prefixes the caller's home folder path onto the front. Effect:
-# always resolved INSIDE the caller's own tree, regardless of
+# any WebDAV path a client sends is always resolved INSIDE the
-# what they wrote.
+# caller's own tree, regardless of what they wrote.
 # The test URLs below use "My Folder - <username>" as a path
 # segment that's GUARANTEED not to match any caller's home name
 # (all home folders are "Personal" post-D0), so the resolver's
 # prepend branch always fires.
 #
 # These tests assert the isolation works (regression guard) and
 # that the service-level verify_owner still acts as
@@ -307,8 +311,13 @@ HTTP 201
 # ─────────────────────────────────────────────────────────────
 # Step 17 – Positive control: bob MKCOL inside his own home.
 # Uses "Personal" — bob's home folder name post-D0
 # (docs/plan/drive.md §3, the canonical default). The resolver
 # detects the URL already starts with the caller's home name and
 # does NOT prepend again, so the new folder lands directly in
 # bob's home rather than in a fresh intermediate.
 # ─────────────────────────────────────────────────────────────
-MKCOL {{base_url}}/webdav/My%20Folder%20-%20bob/bob-webdav-own
+MKCOL {{base_url}}/webdav/Personal/bob-webdav-own
 Authorization: Bearer {{bob_token}}
 HTTP 201
@@ -43,39 +43,50 @@ psql -v ON_ERROR_STOP=1 -c "
 " >/dev/null
 # The OxiCloud server normally provisions a default Personal drive +
-# Owner role_grant on user creation via PersonalDriveLifecycleHook
+# its root folder + Owner role_grant on user creation via
-# (D0). This script bypasses that pipeline — it INSERTs directly into
+# PersonalDriveLifecycleHook (D0). This script bypasses that pipeline
-# auth.users — so we mirror the hook's behaviour here. Without it,
+# — it INSERTs directly into auth.users — so we mirror the hook's
-# integration test fixtures that hand-roll INSERTs into storage.files
+# behaviour here. Without it, integration test fixtures that hand-roll
-# fail with "drive_id not-null violation" (M3 made the column
+# INSERTs into storage.files fail with "drive_id not-null violation"
-# mandatory), and helpers that JOIN auth.users with storage.drives
+# (M3 made the column mandatory), and helpers that JOIN auth.users
-# return RowNotFound.
+# with storage.drives return RowNotFound.
 #
 # Four sequential writes inside one transaction (docs/plan/drive.md §3):
 # drive + root folder + drives.root_folder_id wire-up + Owner role_grant.
 # A single CTE would be more compact but doesn't work — PG's CTE
 # sub-statements share an MVCC snapshot, so a later branch's UPDATE
 # can't match a row inserted by an earlier branch. The transaction
 # form is the production path's shape (DrivePgRepository::create_personal_drive_atomic).
 # Idempotency: skipped on retry by the `default_for_user` precondition.
 echo "[init-schema] provisioning ci-admin's default Personal drive (idempotent)"
 psql -v ON_ERROR_STOP=1 <<'SQL' >/dev/null
-WITH admin AS (
+DO $$
-    SELECT id FROM auth.users WHERE username = 'ci-admin'
+DECLARE
-),
+    admin_id   uuid;
-ins_drive AS (
+    drive_id   uuid;
-    INSERT INTO storage.drives (name, kind, default_for_user, quota_bytes)
+    folder_id  uuid;
-    SELECT 'Personal', 'personal', admin.id, NULL
+BEGIN
-      FROM admin
+    SELECT id INTO admin_id FROM auth.users WHERE username = 'ci-admin';
-     WHERE NOT EXISTS (
+    IF EXISTS (SELECT 1 FROM storage.drives WHERE default_for_user = admin_id) THEN
-         SELECT 1 FROM storage.drives d WHERE d.default_for_user = admin.id
+        RETURN;  -- already provisioned, idempotent no-op
-     )
+    END IF;
-    RETURNING id, default_for_user
+
-)
+    INSERT INTO storage.drives (kind, default_for_user, quota_bytes)
    VALUES ('personal', admin_id, NULL)
    RETURNING id INTO drive_id;
    INSERT INTO storage.folders
        (name, parent_id, user_id, drive_id, created_by, updated_by)
    VALUES ('Personal', NULL, admin_id, drive_id, admin_id, admin_id)
    RETURNING id INTO folder_id;
    UPDATE storage.drives SET root_folder_id = folder_id WHERE id = drive_id;
    INSERT INTO storage.role_grants
        (subject_type, subject_id, resource_type, resource_id, role, granted_by)
-SELECT 'user', ins_drive.default_for_user, 'drive', ins_drive.id, 'owner',
+    VALUES ('user', admin_id, 'drive', drive_id, 'owner', admin_id);
-       ins_drive.default_for_user
+END
-  FROM ins_drive
+$$;
 WHERE NOT EXISTS (
     SELECT 1 FROM storage.role_grants g
      WHERE g.subject_type   = 'user'
        AND g.subject_id     = ins_drive.default_for_user
        AND g.resource_type  = 'drive'
        AND g.resource_id    = ins_drive.id
 );
 SQL
 echo "[init-schema] done"