Merge pull request #413 from EdouardVanbelle/chore/user-lifecycle

Cargo.lock

@@ -3652,6 +3652,7 @@ dependencies = [
  "argon2",
  "async-compression",
  "async-stream",
+ "async-trait",
  "async_zip",
  "aws-config",
  "aws-sdk-s3",

Cargo.toml

@@ -24,6 +24,7 @@ serde = { version = "1.0.228", features = ["derive"] }
 serde_json = "1.0.149"
 futures = "0.3.32"
 async-stream = "0.3.6"
+async-trait = "0.1.83"
 mime_guess = "2.0.5"
 uuid = { version = "1.23.0", features = ["v4", "v7", "serde"] }
 thiserror = "2.0.18"

docs/.vitepress/config.mts

@@ -110,10 +110,12 @@ export default defineConfig({
             { text: "Resource Listing API", link: "/architecture/resource-listing" },
             { text: "Storage Safety", link: "/architecture/file-system-safety" },
             { text: "Database Transactions", link: "/architecture/database-transactions" },
+            { text: "ReBAC Authorization", link: "/architecture/rebac-authorization" },
             { text: "Share Integration", link: "/architecture/share-integration" },
             { text: "Storage Quotas", link: "/architecture/storage-quotas" },
             { text: "File and Blob lifecycle", link: "/architecture/file-and-blob-lifecycle" },
             { text: "ReBAC & Authorization", link: "/architecture/rebac-authorization" },
+            { text: "User lifecycle", link: "/architecture/user-lifecycle" },
           ],
         },
         { text: "FAQ", link: "/faq" },

docs/architecture/user-lifecycle.md

@@ -0,0 +1,221 @@
+# User Lifecycle Hooks
+
+Observer pattern for per-service reactions to user state transitions: created, login, logout, deleted. Mirrors the [File and Blob lifecycle](/architecture/file-and-blob-lifecycle) pattern for files; deliberately diverges from it on two points (async + sync await for most events) because user-lifecycle work is rare and sometimes has hard synchronisation requirements.
+
+## Why hooks
+
+Before this work, four code paths in `AuthApplicationService` each called `create_personal_folder()` immediately after inserting an `auth.users` row (public registration, first-admin bootstrap, admin-creates-user, OIDC just-in-time provisioning), plus a fifth self-heal at `folder_service.rs` for users whose folder somehow went missing. **Five places, one concern, no shared abstraction.** Adding a future per-user resource — default calendar, address book, GPG keyring, external-identity provenance for the upcoming magic-link feature — would have meant touching all five.
+
+Hooks fix this once. Each domain service implements `UserLifecycleHook` for the events it cares about; the dispatcher fires events; services that don't care declare explicit `Ok(())` no-ops. New services register a hook in DI and inherit all four events for free.
+
+## The trait
+
+```rust
+// src/application/ports/user_lifecycle.rs
+#[async_trait]
+pub trait UserLifecycleHook: Send + Sync {
+    fn name(&self) -> &'static str;
+
+    async fn on_user_created(&self, user: &User)
+        -> Result<(), DomainError>;
+
+    async fn on_user_login(&self, user: &User)
+        -> Result<(), DomainError>;
+
+    async fn on_user_logout(&self, user: &User, reason: LogoutReason)
+        -> Result<(), DomainError>;
+
+    async fn on_user_deleted(&self, user: &User, mode: DeletionMode)
+        -> Result<(), DomainError>;
+}
+```
+
+Two enums frame the trait:
+
+```rust
+pub enum LogoutReason {
+    UserInitiated,    // explicit logout
+    SessionExpired,   // TTL hit
+    AdminRevoked,     // admin-initiated single-session revoke
+    AccountDisabled,  // user.active flipped to FALSE → sessions revoked
+    PasswordChanged,  // sibling sessions invalidated by password change
+    TokenReused,      // session-family reuse detection
+}
+
+pub enum DeletionMode {
+    AdminDelete,      // admin deletes via UI; resources go to trash
+    GdprPurge,        // GDPR right-to-erasure; hard-delete everything
+}
+```
+
+**No default impls.** Every implementor must declare all four methods explicitly. Use `Ok(())` for events you don't care about. This forces conscious acknowledgement of every lifecycle event rather than silent inheritance — same convention as `FileLifecycleHook`.
+
+## Dispatcher semantics
+
+`UserLifecycleService` aggregates registered hooks and fans out events with **per-event failure semantics**. The trait itself is uniform; the dispatcher decides whether to await, whether to spawn, and whether `Err` aborts.
+
+| Event              | Awaited?         | On `Err`                                |
+|--------------------|------------------|-----------------------------------------|
+| `on_user_created`  | yes (sync)       | log-and-continue (retry on next login)  |
+| `on_user_login`    | yes (sync)       | log-and-continue (idempotent retry)     |
+| `on_user_logout`   | no (spawned)     | logged, never propagated                |
+| `on_user_deleted`  | yes (sync, in tx) | **abort the transaction** — first `Err` rolls back the user DELETE and propagates to the admin endpoint as a 500 |
+
+The asymmetry is deliberate. `on_user_created` and `on_user_login` must complete before the session token is returned, so callers see consistent state. `on_user_logout` is bookkeeping; the HTTP response shouldn't wait for cache flushes — the dispatcher spawns. `on_user_deleted` will become atomic-with-the-DELETE in PR 4 when a transaction handle joins the trait signature.
+
+```text
+            ┌──────────────────────────────────────────────────┐
+            │ AuthApplicationService                           │
+            │   register / login / logout / delete             │
+            └──────────────────────┬───────────────────────────┘
+                                   │
+                                   ▼
+            ┌──────────────────────────────────────────────────┐
+            │ UserLifecycleService::dispatch_*                 │
+            │   created / login / logout / deleted             │
+            └──────────────────────┬───────────────────────────┘
+                                   │
+                  ┌────────────────┼────────────────┐
+                  ▼                ▼                ▼
+         AuditLifecycleHook  HomeFolderHook  AuthzCacheHook   …
+            (PR 1 only)        (PR 3)           (PR 4)
+```
+
+## Owner-located convention
+
+Each concrete hook impl lives **next to the service that owns the work**, not in a centralised `lifecycle/` directory.
+
+Examples (PR plan):
+
+- `HomeFolderLifecycleHook` lives in `src/application/services/folder_service.rs` — same module as `FolderService`, owner of home-folder policy.
+- `AuthzCacheLifecycleHook` lives in `src/infrastructure/services/pg_acl_engine.rs` — same module as the Moka cache it invalidates.
+- `AuditLifecycleHook` lives in `src/application/services/user_lifecycle_service.rs` (with the dispatcher) — cross-cutting, no domain owner.
+
+This mirrors how `FileLifecycleHook` impls are placed: `ThumbnailRefreshHook` lives in `thumbnail_service.rs`, the audio metadata impl lives in `audio_metadata_service.rs`. A future maintainer reading the folder service sees the lifecycle reactions next to the rest of the folder logic — no jumping between modules to understand why a folder gets created on login.
+
+## Tips for implementors
+
+These are codified in the module-level docstring of `application/ports/user_lifecycle.rs` so they show up in IDE hover.
+
+1. **First-ever login detection.** `on_user_login` fires *before* `user.register_login()` is called, so `user.last_login_at().is_none()` is a reliable "this is the user's first login since account creation" signal. Use it for welcome emails, one-shot default-resource seeding, "complete your profile" prompts.
+
+2. **External-user short-circuit.** Hooks that provision per-user resources (home folder, default calendar, address book, GPG keys, …) must start with `if user.is_external() { return Ok(()); }`. External users (`is_external = TRUE`) are grant-only recipients — they have no home folder and don't consume storage quota. The DB `CHECK (NOT is_external OR storage_used_bytes = 0)` constraint catches code paths that bypass this short-circuit.
+
+   **Subtle but important rule**: external users can **never** be admins. The DB enforces this via `CHECK (NOT (is_external AND role = 'admin'))`. `User::new_external(...)` doesn't accept a role parameter — it always sets `UserRole::User`. To make an existing external user an admin, an admin must first convert them to internal (`UPDATE auth.users SET is_external = FALSE`) and *then* update the role. The two-step process is intentional friction: granting admin to a federated principal would let external identity providers indirectly manage the local instance.
+
+3. **Idempotency is mandatory.** `on_user_login` fires on every successful authentication, not just the first. A hook that creates a resource must check whether the resource already exists before creating it. Cache invalidation, audit deduplication, etc., must all tolerate redundant calls.
+
+4. **External → internal conversion needs no special event.** When an admin flips `is_external = FALSE`, the user's next login fires `on_user_login` with the new flag value. Idempotent hooks see `!is_external` and missing resources → provision. No `on_user_converted` method needed; the safety-net pattern carries the load.
+
+3. **Failure swallowing on create/login.** If your hook returns `Err`, the user is still created/logged in; only your hook's effect is delayed. Log enough detail via `tracing::error!` that subsequent investigation can identify the user. The next successful login's `on_user_login` will retry idempotently.
+
+4. **Per-session logout firing.** When a flow revokes multiple sessions in one call (e.g. `revoke_all_user_sessions` on password change), today the dispatcher fires `on_user_logout` ONCE per logical revoke-call. PR 4's `SessionRevocationLifecycleHook` will refine to once-per-session for proper audit granularity. Hooks must accept N redundant calls with the same reason — keep them idempotent.
+
+5. **`on_user_deleted` runs inside the delete transaction.** The user row still exists when the hook fires; the dispatcher commits only after every hook returns `Ok(())`. Returning `Err` aborts the whole transaction — including the user DELETE itself. Implementors get `tx: &mut sqlx::Transaction<'_, Postgres>` so cleanup queries land in the same tx (e.g. session revocation with audit trail before FK CASCADE wipes the rows). Be conservative about returning `Err`: an abort means the admin's delete operation fails, leaving the user intact.
+
+6. **Hook order is registration order.** The DI factory determines firing sequence. If two hooks have an ordering dependency (e.g. home-folder must exist before default-calendar can be seeded inside it), the dependent hook registers AFTER the producer. Document the convention inline in the DI block.
+
+## Concrete hooks shipped today
+
+| Hook | Lives in | Responsibility |
+|---|---|---|
+| `AuditLifecycleHook` | `src/application/services/user_lifecycle_service.rs` (co-located with dispatcher) | All four events: emits one `tracing::info!(target: "audit", event = "user.*", ...)` per call, with `is_external` as a field. Co-located because audit is cross-cutting with no domain owner. |
+| `HomeFolderLifecycleHook` | `src/application/services/folder_service.rs` (same module as `FolderService`) | `on_user_created` + `on_user_login`: idempotently provision "My Folder - {username}" via `FolderService::ensure_home_folder`. Short-circuits when `user.is_external()`. `on_user_logout`: `Ok(())`. `on_user_deleted`: per-mode `tracing::info!` event so audit distinguishes AdminDelete from GdprPurge — the FK CASCADE on `storage.folders.user_id` handles the actual row removal. Trash-with-retention is documented as future work. |
+| `AuthzCacheLifecycleHook` | `src/infrastructure/services/pg_acl_engine.rs` (same module as the Moka cache it invalidates) | `on_user_logout` + `on_user_deleted`: `engine.invalidate_user_groups_cache(user.id())` — drops the cached transitive-group expansion immediately so a re-login (or a re-created account with the same id) sees fresh memberships without waiting for the 30 s TTL. `on_user_created` + `on_user_login`: `Ok(())` (no stale entry could exist for these). |
+| `SessionRevocationLifecycleHook` | `src/application/services/user_lifecycle_service.rs` (co-located with dispatcher; no dedicated session service module today) | `on_user_deleted`: explicit `session_storage.revoke_all_user_sessions(user.id())` + aggregate audit event (`event = "user.sessions_revoked_on_delete", count = N`). Replaces the silent FK CASCADE with an observable revocation. All other events: `Ok(())`. |
+| `DeletionMode` | enum on the trait | Distinguishes admin-initiated delete (`AdminDelete` — currently identical to GDPR but reserved for a future trash-with-retention policy) from GDPR right-to-erasure purge (`GdprPurge` — for a future sweeper). PR 4 ships the variants; future PRs may add per-mode behaviour. |
+| `ExternalIdentityLifecycleHook` *(no-op stub)* | `src/application/services/external_identity_service.rs` (own module — the future home of the magic-link / OIDC / OCM provenance service) | All four methods are explicit `Ok(())` today. The magic-link PR sequence will populate them: `on_user_created` will INSERT into the future `auth.user_external_identity` side-table for `is_external` users; `on_user_login` will bump `last_verified_at` for GDPR-sweeper purposes; `on_user_logout` and `on_user_deleted` will stay no-ops (FK CASCADE handles row removal). The stub lands now so the magic-link PR fills in hook bodies without touching DI registration. |
+
+### How the delete transaction composes
+
+```text
+AuthApplicationService::delete_user_admin(user_id)
+    │
+    ▼
+BEGIN
+    │
+    ▼
+dispatch_deleted(user, AdminDelete, &mut tx)
+    │
+    ├── AuditLifecycleHook        → tracing::info!(event="user.deleted", mode=...)
+    ├── HomeFolderLifecycleHook   → tracing::info!("home folder will be removed via FK CASCADE")
+    ├── AuthzCacheLifecycleHook   → engine.invalidate_user_groups_cache(user_id)
+    └── SessionRevocationLifecycleHook
+                                  → session_storage.revoke_all_user_sessions(user_id)
+                                  → tracing::info!(event="user.sessions_revoked_on_delete",
+                                                   count=N)
+    │
+    ▼
+DELETE FROM auth.users WHERE id = $1
+    │
+    ▼  (FK CASCADE removes folders, files, app_passwords, device_codes, calendar
+    │   shares, address-book shares, etc.; trg_cleanup_grants_user removes the
+    │   user's grants)
+    │
+    ▼
+COMMIT
+```
+If any hook returns `Err`, the dispatcher propagates it; `delete_user_admin` rolls back the transaction and surfaces the error to the admin endpoint as a 500. The user row, all sessions, all folders/files, all grants — everything stays in place. Hook implementors should keep that strong constraint in mind: returning `Err` from `on_user_deleted` is a heavy hammer.
+
+### Worked example: brand-new user logs in for the first time
+
+1. Client POSTs `/api/auth/login` with valid credentials.
+2. `AuthApplicationService::login()` validates the password against the stored Argon2 hash.
+3. **Before** `user.register_login()` is called, the dispatcher fires `dispatch_login(&user)`. The user's `last_login_at` is still `None` from creation time.
+4. `AuditLifecycleHook::on_user_login` runs first (registration order): emits `event = "user.login", user_id = ..., username = ..., is_external = false, first_login = true`.
+5. `HomeFolderLifecycleHook::on_user_login` runs next: sees `!user.is_external()`, calls `FolderService::ensure_home_folder(uid, username)`. The service checks `list_folders_by_owner(None, uid)` — empty → creates `"My Folder - alice"`. Returns `Ok(true)` (newly created).
+6. Dispatcher finishes. `user.register_login()` is now called, stamping `last_login_at` to the current time.
+7. The session row is INSERTed; access + refresh tokens generated; response returned to the client.
+
+On the user's **second** login: same flow up through step 5, but `ensure_home_folder` finds the existing folder, returns `Ok(false)`, no-op. The `AuditLifecycleHook` still emits an event, but `first_login = false` this time.
+
+If the home folder gets deleted manually (e.g., SQL `DELETE FROM storage.folders WHERE user_id = $1`), the user's **next** login will re-create it — that's the safety-net behaviour the lifecycle hook contractually owns.
+
+### State of the art:
+
+```text
+  DI builds:
+    UserLifecycleService
+      ├── AuditLifecycleHook              (in user_lifecycle_service.rs)
+      ├── HomeFolderLifecycleHook         (in folder_service.rs)
+      ├── AuthzCacheLifecycleHook         (in pg_acl_engine.rs)
+      ├── SessionRevocationLifecycleHook  (in user_lifecycle_service.rs)
+      └── ExternalIdentityLifecycleHook   (in external_identity_service.rs, stubbed)
+
+  AuthApplicationService fires the dispatcher from:
+    ├── register()                  → dispatch_created
+    ├── setup_create_admin()        → dispatch_created
+    ├── admin_create_user()         → dispatch_created
+    ├── OIDC JIT new-user           → dispatch_created + dispatch_login
+    ├── login()                     → dispatch_login (BEFORE register_login)
+    ├── OIDC existing-user login    → dispatch_login (BEFORE register_login)
+    ├── logout()                    → dispatch_logout(UserInitiated)
+    ├── refresh_token reuse         → dispatch_logout(TokenReused)
+    ├── change_password()           → dispatch_logout(PasswordChanged)
+    └── delete_user_admin()         → dispatch_deleted(AdminDelete, tx) — abort-on-Err
+```
+
+## Future events (NOT shipped — design door)
+
+These events are reserved for situations that don't exist yet but probably will. Adding a method to the trait costs every hook impl a new no-op forever, so we don't add them speculatively. Each row lists what would force the addition.
+
+| Future event | Why someone might want it | What would force adding it |
+|---|---|---|
+| `on_user_password_changed` | Notify the user via email; invalidate cached credentials; trigger TOTP re-enrolment | A per-user notification service. Today the existing `revoke_all_user_sessions` cascade fires `on_user_logout(PasswordChanged)` for each session — sufficient for current consumers. |
+| `on_user_role_changed` | Audit promotion to admin; revoke admin-only sessions on demotion | A multi-role system. Today only `admin` / `user` exist and the one-liner audit log at the admin handler covers it. |
+| `on_user_email_changed` | External users: re-verify the new email via magic-link; notify both old and new addresses | When external users start changing their email. Today email is immutable. |
+| `on_user_avatar_changed` | Bust thumbnail caches; sync to federated servers (OCM) | When OCM federation ships. |
+| `on_user_disabled` / `on_user_enabled` | Audit-distinguishable state changes; pause per-user scheduled jobs | When per-user scheduled jobs land. Today `on_user_logout(AccountDisabled)` covers the only consumer. |
+| `on_user_external_to_internal_converted` | Welcome email; pre-provision internal-only resources at conversion time | If admins routinely promote external users and the next-login lag is unacceptable. Today idempotent `on_user_login` handles conversion fine. |
+| `on_user_2fa_enabled` / `on_user_2fa_disabled` | Audit; force re-login of other sessions | When 2FA ships. |
+
+**Rule of thumb for adding any of these**: pair the addition with a default `Ok(())` body (one-time exception to the "no defaults" rule) so existing hooks don't need to declare it. State in the docstring whether the event is await-or-spawn and whether `Err` aborts.
+
+## File map
+
+| Concern | Module |
+|---|---|
+| Trait + `LogoutReason` + `DeletionMode` enums + tips | `src/application/ports/user_lifecycle.rs` |
+| Dispatcher + `AuditLifecycleHook` | `src/application/services/user_lifecycle_service.rs` |
+| Wire-in: created / login / logout / deleted | `src/application/services/auth_application_service.rs` |
+| DI registration | `src/common/di.rs` (constructs the dispatcher) + `src/infrastructure/auth_factory.rs` (threads it into `AuthApplicationService`) |

docs/plan/User-Lifecycle.md

@@ -0,0 +1,358 @@
+# Plan — `UserLifecycleHook` + `is_external` flag
+
+## Context
+
+Today four code paths in `auth_application_service.rs` each call `create_personal_folder()` immediately after inserting an `auth.users` row: public `register`, `setup_create_admin`, admin `create_user`, and OIDC JIT (lines 283, 360, 832, 1277). A fifth self-heal at `folder_service.rs:350-365` retries home-folder creation when listing root folders returns empty. Five places, one concern, no shared abstraction — and adding a future service (calendar, address book, GPG keyring, external-user provenance for the upcoming magic-link feature) would have to touch all five again.
+
+Separately, the upcoming "share with `external@example.com`" feature needs `auth.users` to distinguish recipients-with-no-storage from real internal users. The codebase already declares `Subject::External` (`domain/services/authorization.rs`) but no DB representation exists yet.
+
+This plan introduces a `UserLifecycleHook` trait (mirroring the existing `FileLifecycleHook` / `BlobLifecycleHook` pattern at `application/ports/file_lifecycle.rs`), wires a dispatcher into the four lifecycle events, migrates the scattered eager work into services that own their own lifecycle (each implementing the trait with explicit no-ops for events they don't care about), and adds the `is_external` boolean to `auth.users` so hooks can short-circuit for non-internal users. The change is purely a refactor at first — behaviour is preserved — but it sets up the v2 external-user flow to land as a hook impl rather than a new auth code path.
+
+## Design
+
+### Trait shape
+
+The trait diverges from `FileLifecycleHook`'s sync fire-and-forget model on purpose: file events fire on every upload (hot path, fire-and-forget appropriate); user events are rare (login is seconds-per-user, not requests-per-second) and some require synchronous semantics (provisioning must finish before the session token is returned; deletion cleanup must commit atomically with the user DELETE). The trait is async; the dispatcher decides per-event whether errors abort the flow.
+
+```rust
+// src/application/ports/user_lifecycle.rs (new)
+#[async_trait]
+pub trait UserLifecycleHook: Send + Sync {
+    /// Short identifier used in tracing / error logs. e.g. "home_folder".
+    fn name(&self) -> &'static str;
+
+    /// Fires once after INSERT into auth.users succeeds, regardless of path.
+    async fn on_user_created(&self, user: &User) -> Result<(), DomainError>;
+
+    /// Fires after every successful authentication, before the session
+    /// token is returned. MUST be idempotent (safety net for services
+    /// added after the user existed).
+    async fn on_user_login(&self, user: &User) -> Result<(), DomainError>;
+
+    /// Fires on every session termination. `reason` lets hooks
+    /// distinguish causes (audit cares; cache invalidation does not).
+    async fn on_user_logout(&self, user: &User, reason: LogoutReason)
+        -> Result<(), DomainError>;
+
+    /// Fires inside the same transaction as the auth.users DELETE.
+    /// Returning Err aborts the deletion. `mode` distinguishes admin
+    /// delete (policy-driven cleanup) from GDPR purge (force everything).
+    async fn on_user_deleted(
+        &self,
+        user: &User,
+        mode: DeletionMode,
+        tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
+    ) -> Result<(), DomainError>;
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum LogoutReason {
+    UserInitiated,    // explicit logout
+    SessionExpired,   // TTL hit
+    AdminRevoked,     // single-session revocation by admin
+    AccountDisabled,  // user.active flipped to FALSE → all sessions revoked
+    PasswordChanged,  // sibling sessions invalidated by a password change
+    TokenReused,      // session-family reuse detection (existing feature)
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum DeletionMode { AdminDelete, GdprPurge }
+```
+
+**No default impls.** Every hook must declare all four methods. Use explicit `Ok(())` for events you don't care about — matches the FileLifecycleHook convention and forces conscious acknowledgement.
+
+### Dispatcher
+
+```rust
+// src/application/services/user_lifecycle_service.rs (new)
+pub struct UserLifecycleService {
+    hooks: Vec<Arc<dyn UserLifecycleHook>>,
+}
+
+impl UserLifecycleService {
+    pub fn new() -> Self { Self { hooks: Vec::new() } }
+    pub fn with_hook(mut self, hook: Arc<dyn UserLifecycleHook>) -> Self {
+        self.hooks.push(hook); self
+    }
+
+    // Per-event dispatchers with event-specific failure semantics:
+
+    /// Created: log-and-continue. Next login's `on_user_login` retries
+    /// idempotently if anything fails here.
+    pub async fn dispatch_created(&self, user: &User) {
+        for h in &self.hooks {
+            if let Err(e) = h.on_user_created(user).await {
+                tracing::error!(target: "user_lifecycle",
+                    hook = h.name(), user_id = %user.id(), error = %e,
+                    "on_user_created failed; will retry on next login");
+            }
+        }
+    }
+
+    /// Login: log-and-continue. Same reasoning.
+    pub async fn dispatch_login(&self, user: &User) { /* same shape */ }
+
+    /// Logout: fire-and-forget (spawned), errors logged. The HTTP
+    /// response shouldn't wait for cache flushes.
+    pub fn dispatch_logout(&self, user: User, reason: LogoutReason) {
+        let hooks = self.hooks.clone();
+        tokio::spawn(async move {
+            for h in &hooks {
+                if let Err(e) = h.on_user_logout(&user, reason).await {
+                    tracing::error!(target: "user_lifecycle",
+                        hook = h.name(), reason = ?reason,
+                        user_id = %user.id(), error = %e,
+                        "on_user_logout failed");
+                }
+            }
+        });
+    }
+
+    /// Deleted: propagate first Err to abort the transaction.
+    pub async fn dispatch_deleted(
+        &self,
+        user: &User,
+        mode: DeletionMode,
+        tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
+    ) -> Result<(), DomainError> {
+        for h in &self.hooks {
+            h.on_user_deleted(user, mode, tx).await?;
+        }
+        Ok(())
+    }
+}
+```
+
+### `is_external` flag (additive migration)
+
+New migration `migrations/20260612000002_auth_users_is_external.sql`:
+
+```sql
+-- Adds the is_external flag distinguishing storage-owning internal users
+-- from grant-only external users (magic-link / OIDC-only / future OCM).
+ALTER TABLE auth.users
+    ADD COLUMN IF NOT EXISTS is_external BOOLEAN NOT NULL DEFAULT FALSE;
+
+-- Partial index — most queries are "list internal users" or "list
+-- external users for GDPR purge", never an unfiltered scan.
+CREATE INDEX IF NOT EXISTS idx_users_is_external_login
+    ON auth.users (is_external, last_login_at)
+    WHERE is_external = TRUE;
+
+-- Guard against accidental storage attribution to external users.
+ALTER TABLE auth.users
+    ADD CONSTRAINT users_external_no_storage
+        CHECK (NOT is_external OR storage_used_bytes = 0);
+```
+
+User entity (`src/domain/entities/user.rs`):
+- Add `is_external: bool` field
+- Add getter `pub fn is_external(&self) -> bool`
+- Add factory `User::new_external(username, email, ...)` for the magic-link flow
+- Existing factories (`User::new(...)`) default `is_external = false`
+
+The `Subject::External(uuid)` variant in `domain/services/authorization.rs` becomes redundant once external users live in `auth.users` and are addressed as `Subject::User(uuid)`. Deprecate it in a follow-up — out of scope here to avoid scope creep.
+
+### Concrete hook implementations
+
+**Each hook impl lives in the module of the service that owns the work**, matching the existing convention (`ThumbnailRefreshHook` lives in `src/infrastructure/services/thumbnail_service.rs`; `AudioMetadataService impl FileLifecycleHook` lives in `audio_metadata_service.rs`). There is **no centralised `lifecycle/` directory** — that would invert ownership and make "lifecycle" look like the owner of folder-creation policy when really the folder service owns it.
+
+All four trait methods are explicit per impl; no-ops are `Ok(())` one-liners.
+
+| Hook | Lives in | Responsibility |
+|---|---|---|
+| `HomeFolderLifecycleHook` | `src/application/services/folder_service.rs` (same module as `FolderService`) | Replaces the 4 eager `create_personal_folder` calls + the self-heal. `on_user_created` & `on_user_login`: if `!user.is_external()` and home folder missing, create "My Folder - {username}". `on_user_deleted` (AdminDelete): trash the home folder. `on_user_deleted` (GdprPurge): hard-delete folder + files. `on_user_logout`: `Ok(())`. |
+| `AuthzCacheLifecycleHook` | `src/infrastructure/services/pg_acl_engine.rs` (same module as the Moka cache it invalidates) | Wraps `Arc<PgAclEngine>`. `on_user_logout` & `on_user_deleted`: `engine.invalidate_user_groups_cache(user.id())` (new public method on the engine — one line `self.user_groups_cache.invalidate(id).await`). `on_user_created` & `on_user_login`: `Ok(())`. |
+| `AuditLifecycleHook` | `src/application/services/user_lifecycle_service.rs` (co-located with the dispatcher — cross-cutting, no domain owner) | All four events: `tracing::info!(target: "audit", event = "user.{created\|login\|logout\|deleted}", user_id = %user.id(), is_external = user.is_external(), ...)`. Stays one place for user-lifecycle audit. |
+| `SessionRevocationLifecycleHook` | The session-service module (e.g. `src/application/services/session_service.rs` or wherever `revoke_all_user_sessions` lives — verify at PR-write time) | `on_user_deleted`: explicit `session_storage.revoke_all_user_sessions(user.id(), tx)` for traceable audit (the FK CASCADE would do it but produces no per-session audit event). `on_user_logout` / `on_user_login` / `on_user_created`: `Ok(())`. |
+| `ExternalIdentityLifecycleHook` *(stubbed; populated by the magic-link PR later)* | A future external-identity service module (created with the magic-link PR sequence; for the stub PR, place it in `src/application/services/external_identity_service.rs` as a new module) | `on_user_login`: if `user.is_external()`, bump a `last_verified_at` column on a future `auth.user_external_identity` side-table. Other events: `Ok(())`. Lands as no-op now so the slot exists. |
+
+**Why owner-located, not lifecycle-located**: it preserves the rule that "code about folders lives in the folder module". A future maintainer reading the folder service sees the lifecycle reactions next to the rest of the folder logic. It also makes a future workspace split (see "Crate-split note" at the end of this plan) almost free — each domain takes its hooks with it.
+
+### Tips for hook implementors
+
+These belong in the module-level docstring of `application/ports/user_lifecycle.rs` so the next maintainer reading the trait sees them in IDE hover.
+
+1. **First-ever login detection.** `on_user_login` fires after credentials validate but **before** `user.last_login_at` is updated for this session. So `user.last_login_at().is_none()` is a reliable "this is the first login since account creation" signal. Use it for welcome emails, one-shot default-folder seeding, "complete your profile" prompts, etc.
+
+2. **External-user short-circuit.** Every hook that provisions or manages user-owned resources (folders, calendars, address books) should start with `if user.is_external() { return Ok(()); }`. External users are grant-only; they don't own storage. The `CHECK (NOT is_external OR storage_used_bytes = 0)` constraint catches violations at the DB level.
+
+3. **Idempotency is mandatory.** `on_user_login` fires on every successful authentication. A hook that creates a resource must first check whether the resource already exists. Examples: `HomeFolderLifecycleHook` does `if folder_exists(user_id) { return Ok(()); }` before calling `create_home_folder`. `AuthzCacheLifecycleHook::on_user_logout` is naturally idempotent (cache `invalidate` is a no-op on a missing key).
+
+4. **First call after `is_external = TRUE → FALSE`.** When admin converts an external user to internal (`UPDATE auth.users SET is_external = FALSE`), the user's next login fires `on_user_login` with the new flag value. The home-folder hook sees `!is_external` and that no folder exists → creates it. No special "convert" event needed; idempotency carries the load.
+
+5. **Per-session logout firing.** Disabling a user revokes N sessions in a loop. The dispatcher fires `on_user_logout` **once per session revoked**, all with `reason = AccountDisabled`. Hook implementors must accept N redundant calls (idempotent invalidation, idempotent audit) — do **not** assume "one logout = one user state change". The same applies to `revoke_all_user_sessions` on password change.
+
+6. **Failure swallowing on create/login.** If your hook returns `Err`, the user is still created / logged in; only your hook's effect is delayed. Log enough detail (`tracing::error!`) that a subsequent investigation can identify the user and retry manually. Failure on `on_user_deleted` aborts the transaction — be conservative about returning Err there.
+
+7. **No transaction handle on create/login/logout.** Only `on_user_deleted` gets `&mut Transaction` because deletion is the only event with hard atomic-with-DB requirements. Other hooks open their own connections / pools as needed. This keeps the trait surface minimal.
+
+8. **Hook registration is at DI time.** Hook order is registration order; document this in the DI factory if you ever add an ordering dependency (e.g., HomeFolderLifecycleHook before any future hook that wants to write to that folder).
+
+## Documentation
+
+A new architecture page `docs/architecture/user-lifecycle.md` lands alongside the trait (in PR 1) and grows incrementally with each subsequent PR. Mirrors the structure of the existing `docs/architecture/file-and-blob-lifecycle.md` so readers familiar with the file-side pattern can navigate the user-side analog.
+
+**Outline** (~150 lines):
+
+1. **Context** — why hooks (replaces 4 scattered `create_personal_folder` calls + the self-heal; sets up the magic-link / external-user flow as a pluggable concern).
+2. **The trait** — full signature, the 4 events, `LogoutReason` / `DeletionMode` enums.
+3. **Dispatcher semantics** — per-event failure model (log-and-continue for created/login, fire-and-forget spawn for logout, abort-on-Err for deleted-in-transaction). Diagram.
+4. **Implementation tips** (verbatim from the "Tips for hook implementors" section of this plan — first-login detection via `last_login_at.is_none()`, idempotency, external-user short-circuit, per-session logout firing, …).
+5. **Owner-located convention** — explains why hooks live with their service module rather than a centralised `lifecycle/` directory, with the FileLifecycleHook precedent.
+6. **Concrete hooks shipped today** — table of `HomeFolderLifecycleHook` / `AuthzCacheLifecycleHook` / `AuditLifecycleHook` / `SessionRevocationLifecycleHook` / `ExternalIdentityLifecycleHook` (stub) with one-line summaries and where each lives.
+7. **Recommended future triggers** — the "future triggers" table from this plan (`on_user_password_changed`, `on_user_role_changed`, etc.) so v2 contributors see the design door.
+8. **File map** — same shape as the file map at the bottom of `rebac-authorization.md`.
+
+**VitePress sidebar update** in `docs/.vitepress/config.mts`. The Architecture section already lists "File and Blob lifecycle" (line 104); add immediately after:
+
+```ts
+{ text: "User lifecycle", link: "/architecture/user-lifecycle" },
+```
+
+**Incidental fix while we're in the file**: `docs/architecture/rebac-authorization.md` (created in a previous session) is missing from the sidebar. Add it in the same edit:
+
+```ts
+{ text: "ReBAC Authorization", link: "/architecture/rebac-authorization" },
+```
+
+Place it logically — probably right before "Share Integration" since shares depend on ReBAC concepts.
+
+**Per-PR doc growth**:
+- PR 1: sections 1, 2, 3, 4, 5 (trait, dispatcher, conventions) + the AuditLifecycleHook entry in section 6
+- PR 2: short subsection in section 4 explaining the `is_external` short-circuit pattern
+- PR 3: HomeFolderLifecycleHook entry in section 6, plus a worked example "what happens when a brand-new user logs in"
+- PR 4: AuthzCacheLifecycleHook + SessionRevocationLifecycleHook entries, plus the `DeletionMode` section
+- PR 5: ExternalIdentityLifecycleHook entry + a "this is a placeholder for the upcoming magic-link feature" note
+
+Sidebar entry lands in PR 1; subsequent PRs only edit the markdown content.
+
+## Migration sequencing (5 PRs)
+
+**PR 1: trait + dispatcher + audit hook only.**
+Lands the trait at `application/ports/user_lifecycle.rs`, the dispatcher at `application/services/user_lifecycle_service.rs`, and `AuditLifecycleHook` as the lone registered hook. Wires `dispatch_created` / `dispatch_login` / `dispatch_logout` / `dispatch_deleted` into the existing 4 auth code paths (no behaviour change for users; only audit log gains four new event types). Zero risk; validates plumbing.
+
+**PR 2: `is_external` column + entity field.**
+Migration `20260612000002_auth_users_is_external.sql`, `User::is_external` getter, factory variant, DTO field. All existing rows have `is_external = FALSE` from the column default; no breaking changes. New `POST /api/admin/users` accepts `is_external` (default `false`).
+
+**PR 3: `HomeFolderLifecycleHook`.**
+Register the hook. Remove the 4 eager `create_personal_folder` calls in `auth_application_service.rs:283 / 360 / 832 / 1277`. Remove the self-heal at `folder_service.rs:350-365`. Existing test suite should pass — folder still gets created, just by the hook now. The Hurl suite at `tests/api/run.sh` is the canary.
+
+**PR 4: `AuthzCacheLifecycleHook` + `SessionRevocationLifecycleHook` + `on_user_deleted` policy.**
+Adds the `pub fn invalidate_user_groups_cache(&self, id: Uuid)` method on `PgAclEngine`. Wires the two hooks. Adds `DeletionMode` switching to `HomeFolderLifecycleHook::on_user_deleted` (trash vs hard-delete). Admin-delete endpoint now passes `mode = AdminDelete`; a (future) GDPR sweeper passes `GdprPurge`.
+
+**PR 5: `ExternalIdentityLifecycleHook` stub.**
+Empty no-op hook landed in advance of the magic-link feature so the registration slot exists in DI. Populated in the magic-link PR sequence later.
+
+After PR 3, the cleanup of `create_personal_folder` from `auth_application_service.rs` is complete and the service stops importing `FolderService` for that purpose.
+
+## Recommended future triggers (DON'T ship now)
+
+These are the events users / consumers will eventually want. Each has a "what would make us add it" rationale; absent that, **don't add the method to the trait** — every method adds a no-op to every hook impl forever.
+
+| Future event | Why someone might want it | What would force adding it |
+|---|---|---|
+| `on_user_password_changed` | Notify the user via email; invalidate any cached credentials; trigger TOTP re-enrolment | A real per-user notification service. Today the password-change handler explicitly calls `revoke_all_user_sessions` which fires `on_user_logout(PasswordChanged)` for each session — sufficient for current consumers. |
+| `on_user_role_changed` | Admin grants admin role → audit + maybe send "you're now an admin" email; admin demotion → revoke admin-only sessions | A multi-role system (today only `admin` / `user` exist). Currently a one-liner audit log at the admin handler covers it. |
+| `on_user_email_changed` | External users: re-verify the new email via magic-link before trusting it; internal: notify both old and new addresses; update OIDC mapping | When external users start changing their email. Today email is immutable in the API. |
+| `on_user_username_changed` | Update display names in audit logs that captured the old username; rename the home folder if it embeds the username | When username changes ship. Today username is immutable. |
+| `on_user_avatar_changed` | Bust thumbnail caches downstream; sync to federated servers (OCM) | When OCM federation ships and remote partners need to learn about avatar changes. Today no downstream consumer. |
+| `on_user_quota_changed` | Future per-service quota counters react to admin-changed limits | When quota becomes per-service (today it's a single global counter per user). |
+| `on_user_disabled` / `on_user_enabled` | Audit-distinguishable state changes; pause per-user scheduled jobs | When per-user scheduled jobs land. Today `on_user_logout(AccountDisabled)` covers the only real consumer (sessions). Re-enable triggers `on_user_login` naturally. |
+| `on_user_external_to_internal_converted` | Welcome email; provision the catalog of internal-only resources at conversion time rather than on next login | If admins routinely promote external users and the next-login lag is unacceptable. Today the idempotent `on_user_login` recheck handles conversion fine. |
+| `on_user_oidc_linked` / `on_user_oidc_unlinked` | Audit; sync remote profile data | When users can link/unlink OIDC identities post-creation. Today OIDC linkage is fixed at user-creation time. |
+| `on_user_2fa_enabled` / `on_user_2fa_disabled` | Audit; force re-login of other sessions | When 2FA ships. |
+
+**Rule of thumb for adding any of these later**: add the trait method with a default `Ok(())` body so existing hooks don't need to declare it explicitly (one-time exception to the "no defaults" rule, paid forever after by IDE-discoverable docstrings on the new method). Make sure the docstring states whether it's await-or-spawn semantics and whether failure aborts the parent operation.
+
+## Critical files
+
+**New files** (per PR):
+
+- PR 1: `src/application/ports/user_lifecycle.rs` (trait + `LogoutReason` + `DeletionMode` enums), `src/application/services/user_lifecycle_service.rs` (dispatcher + `AuditLifecycleHook` co-located inside), `docs/architecture/user-lifecycle.md` (architecture doc, outline above)
+- PR 2: `migrations/20260612000002_auth_users_is_external.sql`
+- PR 3: No new files — `HomeFolderLifecycleHook` is added as a new `impl UserLifecycleHook for ...` block inside the **existing** `src/application/services/folder_service.rs` (or a sibling `folder_lifecycle.rs` if folder_service.rs gets too large; verify line count at PR-write time)
+- PR 4: No new files — `AuthzCacheLifecycleHook` added inside the existing `src/infrastructure/services/pg_acl_engine.rs`; `SessionRevocationLifecycleHook` added inside the session-service module
+- PR 5: `src/application/services/external_identity_service.rs` (new module hosting the stub hook)
+
+**Modified files**:
+
+- `src/domain/entities/user.rs` (PR 2): add `is_external` field + getter + factory
+- `src/application/services/auth_application_service.rs` (PRs 1, 3): wire dispatcher into the 4 create / 3 login / 2 logout / 1 delete sites; remove the 4 eager folder-creation calls in PR 3
+- `src/application/services/folder_service.rs` (PR 3): add the `HomeFolderLifecycleHook` impl; remove the self-heal at lines 350-365 (now handled by the hook on next login)
+- `src/infrastructure/services/pg_acl_engine.rs` (PR 4): add `pub fn invalidate_user_groups_cache(&self, id: Uuid)` exposing `user_groups_cache.invalidate(id)`; add the `AuthzCacheLifecycleHook` impl
+- `src/common/di.rs` (PRs 1, 3, 4, 5): construct the `UserLifecycleService` with builder chain, mirror the `FileLifecycleService` registration pattern at lines 264-301
+- `src/application/dtos/user_dto.rs` (PR 2): add `is_external: bool` field
+- `src/interfaces/api/handlers/admin_handler.rs` (PR 2): accept `is_external` in `POST /api/admin/users` request body
+- `docs/.vitepress/config.mts` (PR 1): add "User lifecycle" entry to the Architecture sidebar (line ~104). Also incidentally add the missing "ReBAC Authorization" entry that pre-dated this work
+- `docs/architecture/user-lifecycle.md` (PRs 2, 3, 4, 5): grow the doc incrementally as each hook lands — `is_external` short-circuit note in PR 2, HomeFolderLifecycleHook section in PR 3, etc.
+
+**Existing patterns to reuse**:
+
+- Hook trait + dispatcher pattern: `src/application/ports/file_lifecycle.rs` + `src/application/services/file_lifecycle_service.rs` (the closest analog)
+- DI builder chain: `src/common/di.rs:264-301` (FileLifecycleService construction)
+- Audit tracing convention: `target: "audit"` events emitted by `src/application/services/subject_group_service.rs::create / rename / delete / add_member / remove_member`
+- Per-cache invalidation method on engine: model after how `user_groups_cache` is accessed today in `src/infrastructure/services/pg_acl_engine.rs::expand_user`
+
+## Verification
+
+```bash
+cargo fmt --all
+cargo clippy --all-features --all-targets -- -D warnings
+cargo test --workspace
+biome check --fix static/js/
+tsc -p jsconfig.json --noEmit
+```
+
+After PR 1 (smoke test the plumbing):
+
+1. `cargo run`, then via the UI: register a new user, log in, log out, delete via admin.
+2. `journalctl -t oxicloud | grep "target=user_lifecycle"` (or `RUST_LOG=user_lifecycle=info`) — exactly one event line per action.
+
+After PR 3 (the migration of folder creation):
+
+1. Hurl suite: `bash tests/api/run.sh` — all 13 test files still pass. `permissions.hurl` is the most relevant (it creates `bob` and verifies the home folder).
+2. Manual: register a fresh user via the UI → home folder appears in the file list immediately. Then drop the home folder via SQL (`DELETE FROM storage.folders WHERE user_id = $1`), log out, log back in → folder reappears (the safety-net path).
+3. Confirm via tracing that `dispatch_login` actually ran for an existing user whose folder was already there → no folder creation attempt, no error, just one `on_user_login` audit event.
+
+After PR 4:
+
+1. Authz cache: create a user, log them in, log them out. Inspect `RUST_LOG=oxicloud::infrastructure::services::pg_acl_engine=debug` — cache entry should be invalidated immediately on logout, not after 30s TTL.
+2. User deletion: admin-deletes a user → verify (via audit log) that `on_user_deleted` ran inside the transaction and all sessions were revoked before the `auth.users` row vanished.
+
+After PR 5: no functional change; just confirm `external_identity_hook.rs` compiles and registers in DI as a no-op.
+
+## Out of scope (do NOT bundle into these 5 PRs)
+
+- **The magic-link external-user flow itself.** Lands in a later sequence; this plan only prepares the schema (`is_external`) and the hook slot (`ExternalIdentityLifecycleHook` stub).
+- **Removing `Subject::External` from the domain.** It's currently unused; the cleanup is a separate small PR after PR 2 demonstrates that external users live in `auth.users`.
+- **GDPR sweeper.** The `DeletionMode::GdprPurge` variant exists in PR 4 but no sweeper is wired up — admin-delete uses `AdminDelete`. A scheduled sweeper is its own future work.
+- **Moving the `active` flag transitions through a hook.** PR 4's `on_user_logout(AccountDisabled)` covers it; no `on_user_disabled` method is added (see "future triggers" section).
+- **Side-table for OIDC/OCM provenance** (`auth.user_external_identity`). Lands with the magic-link PR; not needed for `is_external` alone.
+
+## Crate-split note (forward-looking, NOT in this work)
+
+OxiCloud is currently a single Rust crate (~50 kLOC). The lifecycle-hook restructuring above intentionally aligns with the natural domain boundaries (each hook lives with its service) so that a future workspace split is incremental rather than a rewrite. **Not on the table for this work, but worth recording the intended split axis** so subsequent refactors don't paint into a corner:
+
+- **Split by domain bounded context, NOT by hexagonal layer.** Layered split (`oxicloud-domain` / `oxicloud-application` / etc.) makes the common case painful: adding a field to an entity touches 4 crates. Domain split (`oxicloud-files`, `oxicloud-auth`, `oxicloud-rebac`, …) makes the common case stay in one crate.
+- Target shape, illustrative:
+  ```
+  oxicloud-kernel      ← errors, DI primitives, common port traits (incl. UserLifecycleHook)
+  oxicloud-auth        ← users, sessions, OIDC, app passwords; dispatcher lives here
+  oxicloud-rebac       ← groups, grants, engine; registers AuthzCacheLifecycleHook
+  oxicloud-files       ← files, folders, blobs, dedup, thumbnails; registers HomeFolderLifecycleHook
+  oxicloud-sharing     ← shares, magic-link, external identity
+  oxicloud-calendar    ← caldav
+  oxicloud-contacts    ← carddav
+  oxicloud-server      ← Axum wire-up, the binary, DI composition root
+  ```
+  Each domain crate is internally layered. Cross-crate communication goes through `oxicloud-kernel` port traits. The DI factory at `oxicloud-server` is where crates compose into the full application.
+
+- **What today's lifecycle work buys for that future split**: zero rework on hook locations. `HomeFolderLifecycleHook` already lives next to `FolderService`, so it moves with `oxicloud-files`. `AuthzCacheLifecycleHook` moves with `oxicloud-rebac`. The dispatcher in `oxicloud-auth` only knows the trait, never the impls.
+
+- **Cheap things to do now that help the future split**, but are NOT bundled here:
+  - Tighten visibility: prefer `pub(crate)` over `pub` wherever a type isn't intentionally part of the public surface. Catches accidental cross-module reaches at compile time.
+  - Per-domain port traits: today `application/ports/file_lifecycle.rs` is a file-concern port living in the layer dir; eventually it should live under the files-domain module. Refactor when adjacent ports are touched, not as a one-shot move.
+  - Avoid expanding `src/common/` — it tends to absorb anything-shared and become hard to split later.
+
+These are convention recommendations for future PRs, not work items for this plan.

migrations/20260612000002_auth_users_is_external.sql

@@ -0,0 +1,53 @@
+-- ════════════════════════════════════════════════════════════════════════════
+-- Add `is_external` flag to auth.users
+-- ════════════════════════════════════════════════════════════════════════════
+-- Distinguishes storage-owning internal users (default — `is_external = FALSE`)
+-- from grant-only external users (`is_external = TRUE`). External users are
+-- recipients of share-grants who do not have a home folder, do not consume
+-- storage quota, and authenticate via magic-link / OIDC / OCM (future).
+--
+-- This migration is additive — all existing rows default to internal. The
+-- backend code that consumes the flag lands in PR 3 (HomeFolderLifecycleHook
+-- short-circuits when `is_external = TRUE`) and the magic-link flow ships
+-- later still.
+--
+-- Subject::External(uuid) in the domain becomes redundant after this — every
+-- principal is now Subject::User(uuid) with `is_external` as a property, not
+-- a variant. The cleanup happens in a small follow-up after the flag has
+-- been observed in production.
+
+ALTER TABLE auth.users
+    ADD COLUMN IF NOT EXISTS is_external BOOLEAN NOT NULL DEFAULT FALSE;
+
+-- Partial index for the two query patterns that scan by this flag:
+--   - admin "list external users" surface
+--   - GDPR / cleanup sweepers that filter on `is_external = TRUE` and
+--     last_login_at older than a threshold.
+-- Internal-user queries don't go through this index — they ignore the
+-- column entirely.
+CREATE INDEX IF NOT EXISTS idx_users_is_external_login
+    ON auth.users (is_external, last_login_at)
+    WHERE is_external = TRUE;
+
+-- Schema-level safety net: external users must not be charged for storage.
+-- HomeFolderLifecycleHook (PR 3) short-circuits before creating a home
+-- folder for them, so storage_used_bytes should stay at 0. This CHECK
+-- catches any code path that bypasses the hook and tries to attribute
+-- storage to an external user.
+ALTER TABLE auth.users
+    ADD CONSTRAINT users_external_no_storage
+        CHECK (NOT is_external OR storage_used_bytes = 0);
+
+-- Forbid external + admin combination. External users are grant-only
+-- recipients authenticating via federated identity (magic-link, OIDC,
+-- future OCM). Granting them the admin role would let a federated
+-- principal manage the local instance — undesirable. To promote an
+-- external user to admin: first flip is_external to FALSE (converting
+-- them to internal), then update the role separately. The two steps
+-- are intentional friction.
+ALTER TABLE auth.users
+    ADD CONSTRAINT users_external_not_admin
+        CHECK (NOT (is_external AND role = 'admin'));
+
+COMMENT ON COLUMN auth.users.is_external IS
+    'TRUE for grant-only external recipients (magic-link, OIDC-only, OCM federated). FALSE for storage-owning internal users. Set at creation; can be flipped to FALSE by admin to convert external → internal (next login provisions the home folder via HomeFolderLifecycleHook).';

src/application/dtos/settings_dto.rs

@@ -91,9 +91,15 @@ pub struct AdminCreateUserDto {
     /// "admin" or "user"; defaults to "user"
     pub role: Option<String>,
     /// Storage quota in bytes; 0 = unlimited. If omitted, uses role default.
+    /// Ignored when `is_external = true` (external users have no storage).
     pub quota_bytes: Option<i64>,
     /// Whether the account is active; defaults to true
     pub active: Option<bool>,
+    /// `true` to create a grant-only external user (no home folder, no
+    /// storage quota). Defaults to `false` (internal user). External
+    /// users authenticate via magic-link / OIDC / OCM federation —
+    /// password is set but never used.
+    pub is_external: Option<bool>,
 }
 
 /// Request body for admin password reset

src/application/dtos/user_dto.rs

@@ -19,6 +19,11 @@ pub struct UserDto {
     pub auth_provider: String,
     pub image: Option<String>,
     pub can_edit_image: bool,
+    /// `true` for grant-only external recipients (magic-link, OIDC-only,
+    /// future OCM federated). External users have no home folder and
+    /// can't own storage; their quota is always 0. Internal users
+    /// default to `false`.
+    pub is_external: bool,
 }
 
 impl From<User> for UserDto {
@@ -37,6 +42,7 @@ impl From<User> for UserDto {
             auth_provider: user.oidc_provider().unwrap_or("local").to_string(),
             image: user.image().map(|s| s.to_string()),
             can_edit_image: !user.is_oidc_user(),
+            is_external: user.is_external(),
         }
     }
 }

src/application/ports/mod.rs

@@ -21,4 +21,5 @@ pub mod storage_ports;
 pub mod thumbnail_ports;
 pub mod transcode_ports;
 pub mod trash_ports;
+pub mod user_lifecycle;
 pub mod zip_ports;

src/application/ports/user_lifecycle.rs

@@ -0,0 +1,196 @@
+//! User-lifecycle hook port.
+//!
+//! Observer notified by [`AuthApplicationService`] when a user transitions
+//! through one of four lifecycle events: created, login, logout, deleted.
+//! Register concrete impls with [`UserLifecycleService`] during DI wiring;
+//! the dispatcher fans out each event to every registered hook.
+//!
+//! Each impl owns ONE concern. Folder service owns home-folder provisioning,
+//! authz engine owns its cache invalidation, audit service owns the audit
+//! trail, etc. New services plug in by registering a hook; the dispatcher
+//! itself never gains domain knowledge.
+//!
+//! # Convention: explicit no-ops
+//!
+//! Every implementor **must** provide all four methods — use an explicit
+//! one-liner `Ok(())` for events the implementor does not care about. This
+//! forces conscious acknowledgement of every lifecycle event rather than
+//! silent omission via trait defaults. Mirrors the [`FileLifecycleHook`]
+//! convention at `application/ports/file_lifecycle.rs`.
+//!
+//! # Convention: async + per-event semantics
+//!
+//! Unlike [`FileLifecycleHook`] (sync fire-and-forget), user-lifecycle
+//! events are async because some require synchronous semantics:
+//! provisioning must finish before the session token is returned;
+//! deletion cleanup must commit atomically with the user DELETE.
+//!
+//! Per-event failure model (encoded in the dispatcher, not the trait):
+//!
+//! | Event              | Awaited? | On `Err`?                              |
+//! |--------------------|----------|----------------------------------------|
+//! | `on_user_created`  | yes      | log-and-continue (retry on next login) |
+//! | `on_user_login`    | yes      | log-and-continue (idempotent retry)    |
+//! | `on_user_logout`   | no       | fire-and-forget (spawned), error logged|
+//! | `on_user_deleted`  | yes (in tx) | abort the transaction (Err propagates) |
+//!
+//! # Tips for hook implementors
+//!
+//! 1. **First-ever login detection.** `on_user_login` fires after
+//!    credentials validate but **before** `user.register_login()` is
+//!    called for this session. So `user.last_login_at().is_none()` is a
+//!    reliable "this is the first login since account creation" signal —
+//!    useful for welcome emails, one-shot default-resource seeding,
+//!    "complete your profile" prompts.
+//!
+//! 2. **External-user short-circuit.** Every hook that provisions or
+//!    manages user-owned resources (folders, calendars, address books)
+//!    should start with `if user.is_external() { return Ok(()); }`.
+//!    External users are grant-only — they don't own storage. The
+//!    `is_external` flag lands in PR 2 of this work; until then, treat
+//!    every user as internal.
+//!
+//! 3. **Idempotency is mandatory.** `on_user_login` fires on every
+//!    successful authentication. A hook that creates a resource must
+//!    first check whether the resource already exists. Same for cache
+//!    invalidation, audit deduplication, etc. The `on_user_login`
+//!    safety-net only works if hooks no-op when their work is already
+//!    done.
+//!
+//! 4. **External → internal conversion needs no special event.** When
+//!    admin converts an external user to internal (`UPDATE auth.users
+//!    SET is_external = FALSE`), the user's next login fires
+//!    `on_user_login` with the new flag value. Idempotent hooks see
+//!    `!is_external` + missing resources → provision. No
+//!    `on_user_converted` method needed.
+//!
+//! 5. **Per-session logout firing.** When a flow revokes multiple
+//!    sessions (e.g. `revoke_all_user_sessions` on password change),
+//!    today the dispatcher fires `on_user_logout` ONCE per logical
+//!    revoke-call. PR 4's `SessionRevocationLifecycleHook` will refine
+//!    this to once-per-session for proper audit granularity. Hooks must
+//!    therefore accept N redundant calls with the same reason — keep
+//!    them idempotent and side-effect-free.
+//!
+//! 6. **Failure swallowing on create/login.** If your hook returns
+//!    `Err`, the user is still created / logged in; only your hook's
+//!    effect is delayed. Log enough detail via `tracing::error!` that a
+//!    subsequent investigation can identify the user and retry
+//!    manually. The `on_user_login` safety-net will retry on the next
+//!    successful authentication.
+//!
+//! 7. **`on_user_deleted` runs inside the delete transaction.** The
+//!    user row still exists when the hook fires; the dispatcher commits
+//!    only after every hook returns `Ok(())`. Returning `Err` aborts
+//!    the whole transaction — including the user DELETE itself.
+//!    Implementors get `tx: &mut sqlx::Transaction<'_, Postgres>` so
+//!    cleanup queries land in the same tx (e.g. session revocation
+//!    with audit trail before FK CASCADE wipes the rows). Be
+//!    conservative about returning `Err`: an abort means the admin's
+//!    delete operation fails, leaving the user intact.
+//!
+//! 8. **Hook order is registration order.** The DI factory at
+//!    [`AppServiceFactory`] determines the firing sequence. If two hooks
+//!    have an ordering dependency (e.g. home-folder must exist before
+//!    default-calendar can be seeded inside it), the dependent hook
+//!    registers AFTER the producer. Document the convention in the DI
+//!    block where order matters.
+
+use async_trait::async_trait;
+
+use crate::common::errors::DomainError;
+use crate::domain::entities::user::User;
+
+/// Reason a user session is ending. Hooks that don't care about the cause
+/// (e.g. cache invalidation) ignore the value; audit-style hooks branch on
+/// it to emit distinguishable events.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum LogoutReason {
+    /// User clicked logout. Single-session.
+    UserInitiated,
+    /// Session TTL hit. Single-session.
+    SessionExpired,
+    /// Admin invoked single-session revocation (e.g. "log out other
+    /// devices"). Today this fires from `logout_all` and from individual
+    /// admin endpoints if/when they exist.
+    AdminRevoked,
+    /// `user.active` flipped to `FALSE` → all sessions revoked. Fires once
+    /// per logical revoke-call today (see tip #5).
+    AccountDisabled,
+    /// Password was changed → sibling sessions invalidated to force re-login
+    /// with the new password.
+    PasswordChanged,
+    /// Refresh-token reuse detected by the session-family guard. Entire
+    /// family revoked because the rotation was probably stolen.
+    TokenReused,
+}
+
+/// How aggressively `on_user_deleted` cleanup should run. Today both
+/// variants are equivalent (only `AuditLifecycleHook` exists, and it logs
+/// regardless). The split exists so PR 4's `HomeFolderLifecycleHook` can
+/// trash on `AdminDelete` but hard-delete on `GdprPurge`.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum DeletionMode {
+    /// Admin deletes a user through the UI. Resources move to trash for
+    /// the retention window; recoverable.
+    AdminDelete,
+    /// GDPR right-to-erasure sweeper. Hard-delete everything; not
+    /// recoverable. (No sweeper is wired today; the variant is reserved.)
+    GdprPurge,
+}
+
+/// Observer for user-lifecycle events. See module-level docstring for the
+/// convention, semantics, and 8 tips for implementors.
+///
+/// `#[async_trait]` is required to make the trait `dyn`-compatible —
+/// the dispatcher holds `Arc<dyn UserLifecycleHook>`. Without it,
+/// native `async fn in trait` returns an opaque type that has no vtable
+/// representation. The same crate (`async-trait` 0.1.x) is used by other
+/// async ecosystem deps and was already transitively in Cargo.lock.
+#[async_trait]
+pub trait UserLifecycleHook: Send + Sync {
+    /// Short identifier used in tracing / error logs. Example: `"home_folder"`,
+    /// `"audit"`, `"authz_cache"`.
+    fn name(&self) -> &'static str;
+
+    /// Fires once after INSERT into `auth.users` succeeds, regardless of
+    /// the creation path (self-register, admin-create, OIDC JIT, future
+    /// magic-link bootstrap).
+    ///
+    /// The dispatcher logs `Err` and continues — the user is still
+    /// created and the next `on_user_login` will run an idempotent retry.
+    async fn on_user_created(&self, user: &User) -> Result<(), DomainError>;
+
+    /// Fires after every successful authentication, BEFORE the user's
+    /// `last_login_at` is updated for this session and BEFORE the session
+    /// token is returned to the caller.
+    ///
+    /// **Idempotency is mandatory** — this fires on every login, not just
+    /// the first. Hooks that provision must check whether their resource
+    /// already exists before creating it. See tip #3 in the module
+    /// docstring.
+    ///
+    /// `user.last_login_at().is_none()` distinguishes the first-ever
+    /// login from subsequent ones. See tip #1.
+    async fn on_user_login(&self, user: &User) -> Result<(), DomainError>;
+
+    /// Fires on session termination. `reason` lets hooks distinguish
+    /// causes — audit cares; cache invalidation usually doesn't.
+    ///
+    /// Spawned by the dispatcher — `Err` is logged but never propagates.
+    /// The HTTP response shouldn't wait for downstream cache flushes.
+    async fn on_user_logout(&self, user: &User, reason: LogoutReason) -> Result<(), DomainError>;
+
+    /// Fires inside the `delete_user_admin` transaction, BEFORE the
+    /// `DELETE FROM auth.users` row removal. The user row still exists
+    /// at this point; `user.id()` is safe to reference in queries on
+    /// the same `tx`. Returning `Err` rolls back the transaction —
+    /// the user is NOT deleted and the admin's request fails. See
+    /// tip #7 in the module docstring.
+    async fn on_user_deleted(
+        &self,
+        user: &User,
+        mode: DeletionMode,
+        tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
+    ) -> Result<(), DomainError>;
+}

src/application/services/auth_application_service.rs

@@ -5,8 +5,8 @@ use crate::application::ports::auth_ports::{
     OidcIdClaims, OidcServicePort, PasswordHasherPort, SessionStoragePort, TokenServicePort,
     UserStoragePort,
 };
-use crate::application::ports::folder_ports::FolderUseCase;
+use crate::application::ports::user_lifecycle::{DeletionMode, LogoutReason};
-use crate::application::services::folder_service::FolderService;
+use crate::application::services::user_lifecycle_service::UserLifecycleService;
 use crate::common::config::OidcConfig;
 use crate::common::errors::{DomainError, ErrorKind};
 use crate::domain::entities::session::Session;
@@ -71,7 +71,12 @@ pub struct AuthApplicationService {
     session_storage: Arc<SessionPgRepository>,
     password_hasher: Arc<Argon2PasswordHasher>,
     token_service: Arc<JwtTokenService>,
-    folder_service: Option<Arc<FolderService>>,
+    /// Dispatcher for user-lifecycle events. `None` only in tests that don't
+    /// exercise the lifecycle path; production DI always wires this.
+    /// HomeFolderLifecycleHook (registered on this dispatcher) owns the
+    /// per-user folder provisioning that AuthApplicationService used to do
+    /// inline pre-PR 3.
+    user_lifecycle: Option<Arc<UserLifecycleService>>,
     /// Path to the storage directory, used for disk-space–aware quota calculation
     storage_path: PathBuf,
     oidc: RwLock<OidcState>,
@@ -96,7 +101,7 @@ impl AuthApplicationService {
             session_storage,
             password_hasher,
             token_service,
-            folder_service: None,
+            user_lifecycle: None,
             storage_path,
             oidc: RwLock::new(OidcState {
                 service: None,
@@ -159,9 +164,11 @@ impl AuthApplicationService {
         }
     }
 
-    /// Configures the folder service, needed to create personal folders
+    /// Configures the user-lifecycle dispatcher. Wired by the DI factory
-    pub fn with_folder_service(mut self, folder_service: Arc<FolderService>) -> Self {
+    /// after core services are up. PR 1: only AuditLifecycleHook is
-        self.folder_service = Some(folder_service);
+    /// registered, so calls without this configured silently no-op.
+    pub fn with_user_lifecycle(mut self, lifecycle: Arc<UserLifecycleService>) -> Self {
+        self.user_lifecycle = Some(lifecycle);
         self
     }
 
@@ -279,9 +286,12 @@ impl AuthApplicationService {
         // Save user
         let created_user = self.user_storage.create_user(user).await?;
 
-        // Create personal folder for the user
+        // Lifecycle: HomeFolderLifecycleHook handles personal-folder
-        self.create_personal_folder(&dto.username, created_user.id())
+        // creation (was inlined here pre-PR 3); audit log + future
-            .await;
+        // provisioning steps land here too.
+        if let Some(lc) = &self.user_lifecycle {
+            lc.dispatch_created(&created_user).await;
+        }
 
         tracing::info!("User registered: {}", created_user.id());
         Ok(UserDto::from(created_user))
@@ -356,9 +366,13 @@ impl AuthApplicationService {
 
         let created_user = self.user_storage.create_user(user).await?;
 
-        // Create personal folder for the admin
+        // Lifecycle: notify hooks. PR 3 moves home-folder creation into
-        self.create_personal_folder(&username, created_user.id())
+        // HomeFolderLifecycleHook fired here.
-            .await;
+        // Lifecycle: HomeFolderLifecycleHook provisions the admin's
+        // home folder. Audit logs the creation event.
+        if let Some(lc) = &self.user_lifecycle {
+            lc.dispatch_created(&created_user).await;
+        }
 
         tracing::info!(
             "Initial admin created via setup: {} ({})",
@@ -401,6 +415,13 @@ impl AuthApplicationService {
             ));
         }
 
+        // Lifecycle: dispatch login BEFORE register_login() so hooks
+        // observing `last_login_at().is_none()` see "first ever login"
+        // correctly. See tip #1 in user_lifecycle.rs.
+        if let Some(lc) = &self.user_lifecycle {
+            lc.dispatch_login(&user).await;
+        }
+
         // Update last login
         user.register_login();
         self.user_storage.update_user(user.clone()).await?;
@@ -496,6 +517,13 @@ impl AuthApplicationService {
             self.session_storage
                 .revoke_session_family(session.family_id())
                 .await?;
+            // Lifecycle: TokenReused logout — fired once per logical
+            // revoke-family call. PR 4 may refine to per-session firing.
+            if let Some(lc) = &self.user_lifecycle
+                && let Ok(user) = self.user_storage.get_user_by_id(session.user_id()).await
+            {
+                lc.dispatch_logout(user, LogoutReason::TokenReused);
+            }
             return Err(DomainError::new(
                 ErrorKind::AccessDenied,
                 "Auth",
@@ -576,6 +604,15 @@ impl AuthApplicationService {
         // Revoke session
         self.session_storage.revoke_session(session.id()).await?;
 
+        // Lifecycle: notify hooks. One extra DB roundtrip per logout
+        // (user load) is acceptable — logout is rare. Failure to load
+        // the user is non-fatal: we already revoked the session.
+        if let Some(lc) = &self.user_lifecycle
+            && let Ok(user) = self.user_storage.get_user_by_id(user_id).await
+        {
+            lc.dispatch_logout(user, LogoutReason::UserInitiated);
+        }
+
         Ok(())
     }
 
@@ -637,13 +674,19 @@ impl AuthApplicationService {
         user.update_password_hash(new_hash);
 
         // Save updated user
-        self.user_storage.update_user(user).await?;
+        self.user_storage.update_user(user.clone()).await?;
 
         // Optional: revoke all sessions to force re-login with new password
         self.session_storage
             .revoke_all_user_sessions(user_id)
             .await?;
 
+        // Lifecycle: PasswordChanged logout — fired once per logical
+        // revoke-all call. PR 4 may refine to per-session firing.
+        if let Some(lc) = &self.user_lifecycle {
+            lc.dispatch_logout(user, LogoutReason::PasswordChanged);
+        }
+
         Ok(())
     }
 
@@ -802,21 +845,60 @@ impl AuthApplicationService {
             _ => UserRole::User,
         };
 
-        // Determine quota, capped to available disk space
+        let is_external = dto.is_external.unwrap_or(false);
-        let quota = dto.quota_bytes.unwrap_or_else(|| self.capped_quota(&role));
 
-        // Hash password
+        // Forbid external + admin combo. The DB `users_external_not_admin`
+        // CHECK constraint would catch this too, but a 400 with an
+        // explanatory message is friendlier than a generic 500 from a
+        // constraint violation. See the CHECK definition in
+        // migrations/20260612000002_auth_users_is_external.sql for the
+        // rationale.
+        if is_external && matches!(role, UserRole::Admin) {
+            return Err(DomainError::new(
+                ErrorKind::InvalidInput,
+                "User",
+                "External users cannot be admins. To promote an external user to admin, \
+                 first convert them to internal (set is_external = false), then update \
+                 the role separately."
+                    .to_string(),
+            ));
+        }
+
+        // External users never own storage. The DB `users_external_no_storage`
+        // CHECK constraint enforces this; setting quota=0 here keeps the
+        // domain consistent and matches `User::new_external`.
+        let quota = if is_external {
+            0
+        } else {
+            dto.quota_bytes.unwrap_or_else(|| self.capped_quota(&role))
+        };
+
+        // Hash password (kept for both internal and external users — for
+        // external users it's currently unused since they authenticate via
+        // magic-link / OIDC, but the DB column is NOT NULL).
         let password_hash = self.password_hasher.hash_password(&dto.password).await?;
 
-        // Create domain entity
+        // Create domain entity. External path uses `new_external` so the
-        let user =
+        // is_external flag is set + the EXTERNAL placeholder password
-            User::new(dto.username.clone(), email, password_hash, role, quota).map_err(|e| {
+        // marker is applied for clarity in DB inspection. `new_external`
-                DomainError::new(
+        // forces role=User (the admin+external combo was rejected above).
-                    ErrorKind::InvalidInput,
+        let user = if is_external {
-                    "User",
+            User::new_external(dto.username.clone(), email).map(|mut u| {
-                    format!("Error creating user: {}", e),
+                // The hashed password from the request is unused for auth
-                )
+                // but is persisted so audit-trail integrity is preserved.
-            })?;
+                u.update_password_hash(password_hash);
+                u
+            })
+        } else {
+            User::new(dto.username.clone(), email, password_hash, role, quota)
+        }
+        .map_err(|e| {
+            DomainError::new(
+                ErrorKind::InvalidInput,
+                "User",
+                format!("Error creating user: {}", e),
+            )
+        })?;
 
         // Persist
         let created = self.user_storage.create_user(user).await?;
@@ -828,11 +910,19 @@ impl AuthApplicationService {
                 .await?;
         }
 
-        // Create personal folder
+        // Lifecycle: HomeFolderLifecycleHook handles the home-folder
-        self.create_personal_folder(&dto.username, created.id())
+        // provisioning (idempotent + short-circuits on is_external).
-            .await;
+        // Audit logs the creation event.
+        if let Some(lc) = &self.user_lifecycle {
+            lc.dispatch_created(&created).await;
+        }
 
-        tracing::info!("Admin created user: {} ({})", dto.username, created.id());
+        tracing::info!(
+            "Admin created user: {} ({}, is_external={})",
+            dto.username,
+            created.id(),
+            created.is_external()
+        );
         Ok(UserDto::from(created))
     }
 
@@ -878,12 +968,47 @@ impl AuthApplicationService {
         Ok(UserDto::from(user))
     }
 
-    /// Delete a user by ID (admin only)
+    /// Delete a user by ID (admin only).
+    ///
+    /// Runs the whole flow in a single transaction so the lifecycle
+    /// hooks (`SessionRevocationLifecycleHook` revoking sessions with
+    /// audit, `AuthzCacheLifecycleHook` invalidating the Moka cache,
+    /// `HomeFolderLifecycleHook` for future trash policy, …) can do
+    /// their work atomically with the user DELETE. If any hook returns
+    /// `Err`, the transaction rolls back and the user remains intact.
     pub async fn delete_user_admin(&self, user_id: Uuid) -> Result<(), DomainError> {
-        // Prevent deleting yourself
         let user = self.user_storage.get_user_by_id(user_id).await?;
         tracing::info!("Admin deleting user: {} ({})", user.username(), user_id);
-        self.user_storage.delete_user(user_id).await
+
+        let mut tx = self
+            .user_storage
+            .pool()
+            .begin()
+            .await
+            .map_err(|e| DomainError::internal_error("Auth", format!("begin tx: {}", e)))?;
+
+        // Hooks run inside the tx, BEFORE the user DELETE. They see the
+        // row still present and can write cleanup queries against the
+        // same tx (e.g. session revocation with per-session audit).
+        if let Some(lc) = &self.user_lifecycle {
+            lc.dispatch_deleted(&user, DeletionMode::AdminDelete, &mut tx)
+                .await?;
+        }
+
+        // Now the DELETE — FK CASCADE handles the downstream cleanup
+        // (sessions, folders, files, …) for anything the hooks didn't
+        // explicitly remove.
+        sqlx::query("DELETE FROM auth.users WHERE id = $1")
+            .bind(user_id)
+            .execute(&mut *tx)
+            .await
+            .map_err(|e| DomainError::internal_error("Auth", format!("delete user: {}", e)))?;
+
+        tx.commit()
+            .await
+            .map_err(|e| DomainError::internal_error("Auth", format!("commit: {}", e)))?;
+
+        Ok(())
     }
 
     /// Activate or deactivate a user (admin only)
@@ -1175,7 +1300,12 @@ impl AuthApplicationService {
             .await
         {
             Ok(mut existing_user) => {
-                // User exists — update last login and sync avatar from IdP
+                // User exists — dispatch login BEFORE register_login() so
+                // hooks observe `last_login_at = None` on the very first
+                // login (see tip #1 in the trait docstring).
+                if let Some(lc) = &self.user_lifecycle {
+                    lc.dispatch_login(&existing_user).await;
+                }
                 existing_user.register_login();
                 existing_user.set_image(claims.picture.clone());
                 self.user_storage.update_user(existing_user.clone()).await?;
@@ -1273,9 +1403,14 @@ impl AuthApplicationService {
 
                 let created_user = self.user_storage.create_user(new_user).await?;
 
-                // Create personal folder
+                // Lifecycle: created (audit + home-folder provisioning) +
-                self.create_personal_folder(&username, created_user.id())
+                // login (no register_login() for a fresh OIDC user means
-                    .await;
+                // `last_login_at` is naturally None → first-login detection
+                // works). HomeFolderLifecycleHook creates the home folder.
+                if let Some(lc) = &self.user_lifecycle {
+                    lc.dispatch_created(&created_user).await;
+                    lc.dispatch_login(&created_user).await;
+                }
 
                 tracing::info!(
                     "OIDC user provisioned: {} (provider: {}, sub: {})",
@@ -1371,32 +1506,10 @@ impl AuthApplicationService {
         UserRole::User
     }
 
-    /// Helper to create a personal folder for a new user
+    // `create_personal_folder` was removed in PR 3 of the
-    async fn create_personal_folder(&self, username: &str, user_id: Uuid) {
+    // UserLifecycleHook migration — home-folder provisioning is now
-        if let Some(folder_service) = &self.folder_service {
+    // owned by `HomeFolderLifecycleHook` in folder_service.rs and runs
-            let folder_name = format!("My Folder - {}", username);
+    // via `dispatch_created` / `dispatch_login`.
-            match folder_service
-                .create_home_folder(user_id, folder_name.clone())
-                .await
-            {
-                Ok(folder) => {
-                    tracing::info!(
-                        "Personal folder created for user {}: {} (ID: {})",
-                        user_id,
-                        folder.name,
-                        folder.id
-                    );
-                }
-                Err(e) => {
-                    tracing::error!(
-                        "Failed to create personal folder for user {}: {}",
-                        user_id,
-                        e
-                    );
-                }
-            }
-        }
-    }
 }
 
 /// URL-safe base64 encoding without padding (RFC 4648 §5)

src/application/services/external_identity_service.rs

@@ -0,0 +1,86 @@
+//! External-identity service.
+//!
+//! Houses the lifecycle hook for grant-only external users — recipients
+//! authenticating via magic-link, OIDC-only, or OCM federation rather than
+//! a local password. Today the module ships only a **stubbed
+//! `ExternalIdentityLifecycleHook`**: it's registered on the dispatcher
+//! so the slot exists in DI, but every method is an explicit `Ok(())`
+//! no-op. The magic-link PR sequence will fill in the bodies.
+//!
+//! # What the populated hook will do (forward reference)
+//!
+//! A future `auth.user_external_identity` side-table will store provenance
+//! per external user:
+//!
+//! ```text
+//! user_id           UUID PRIMARY KEY REFERENCES auth.users(id) ON DELETE CASCADE
+//! source            TEXT NOT NULL CHECK (source IN ('magic_link','oidc','ocm'))
+//! issuer            TEXT     -- OIDC iss URL or OCM partner FQDN
+//! external_sub      TEXT     -- OIDC sub or OCM remote user id; NULL for magic_link
+//! last_verified_at  TIMESTAMPTZ NOT NULL DEFAULT now()
+//! UNIQUE (source, issuer, external_sub)
+//! ```
+//!
+//! Then this hook will:
+//!
+//! | Event             | Action |
+//! |-------------------|--------|
+//! | `on_user_created` | If `user.is_external()`, INSERT a row into `auth.user_external_identity` with the source/issuer/sub captured from the create flow (magic-link bootstrap, OIDC JIT, OCM federation). |
+//! | `on_user_login`   | If `user.is_external()`, `UPDATE … SET last_verified_at = NOW()` for the user's provenance row. Used by the GDPR sweeper to identify "external users we haven't heard from in 13 months". |
+//! | `on_user_logout`  | `Ok(())` — provenance is connection-level, not session-level. |
+//! | `on_user_deleted` | `Ok(())` — the FK CASCADE on `user_external_identity.user_id` handles row removal. |
+//!
+//! Today (PR 5): all four methods return `Ok(())` so the dispatcher
+//! exercises the registration path without any side effect.
+
+use async_trait::async_trait;
+
+use crate::application::ports::user_lifecycle::{DeletionMode, LogoutReason, UserLifecycleHook};
+use crate::common::errors::DomainError;
+use crate::domain::entities::user::User;
+
+/// **Stubbed for now.** Populates the future `auth.user_external_identity`
+/// side-table when the magic-link / external-user flow ships. Registered
+/// on the dispatcher today as a no-op so the magic-link PR doesn't need to
+/// touch DI — it only fills in the hook body.
+///
+/// All four `UserLifecycleHook` methods are explicit `Ok(())` per the
+/// "no defaults — every event acknowledged" convention.
+pub struct ExternalIdentityLifecycleHook;
+
+#[async_trait]
+impl UserLifecycleHook for ExternalIdentityLifecycleHook {
+    fn name(&self) -> &'static str {
+        "external_identity"
+    }
+
+    async fn on_user_created(&self, _user: &User) -> Result<(), DomainError> {
+        // STUB: magic-link / OIDC JIT / OCM bootstrap PR will INSERT the
+        // provenance row here when `user.is_external()`.
+        Ok(())
+    }
+
+    async fn on_user_login(&self, _user: &User) -> Result<(), DomainError> {
+        // STUB: magic-link PR will UPDATE `last_verified_at` here so the
+        // GDPR sweeper can identify dormant external users.
+        Ok(())
+    }
+
+    async fn on_user_logout(&self, _user: &User, _reason: LogoutReason) -> Result<(), DomainError> {
+        // Provenance is connection-level, not session-level — no work
+        // to do on logout even in the populated future version.
+        Ok(())
+    }
+
+    async fn on_user_deleted(
+        &self,
+        _user: &User,
+        _mode: DeletionMode,
+        _tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
+    ) -> Result<(), DomainError> {
+        // FK CASCADE on `auth.user_external_identity.user_id` will
+        // handle row removal automatically — no work needed here even
+        // in the populated future version.
+        Ok(())
+    }
+}

src/application/services/folder_service.rs

@@ -315,7 +315,12 @@ impl FolderUseCase for FolderService {
     }
 
     /// Lists folders scoped to a specific owner.
-    /// Self-healing: if listing root folders and none exist, creates a home folder.
+    ///
+    /// **Note (post PR 3):** the self-heal block that auto-created a
+    /// home folder when listing returned empty has been removed.
+    /// `HomeFolderLifecycleHook` (registered on `UserLifecycleService`)
+    /// now provisions the folder on `on_user_created` / `on_user_login`,
+    /// idempotently, so the listing path no longer needs to self-heal.
     async fn list_folders_with_perms(
         &self,
         parent_id: Option<&str>,
@@ -331,62 +336,23 @@ impl FolderUseCase for FolderService {
                 )
                 .await?;
             return self.list_folders(parent_id).await;
-        } else {
-            // No parent defined grab user's homes
-            let folders = self
-                .folder_storage
-                .list_folders_by_owner(parent_id, caller_id)
-                .await
-                .map_err(|e| {
-                    DomainError::internal_error(
-                        "FolderStorage",
-                        format!(
-                            "Failed to list folders for owner '{}' in parent {:?}: {}",
-                            caller_id, parent_id, e
-                        ),
-                    )
-                })?;
-
-            if folders.is_empty() {
-                // Self-healing: if listing root folders and none exist, create a home folder
-                // This ensures the frontend always gets a valid userHomeFolderId
-                tracing::info!(
-                    "No root folders found for user {}, creating home folder automatically",
-                    caller_id
-                );
-                let owner_id_short = {
-                    let s = caller_id.to_string();
-                    s[..8.min(s.len())].to_string()
-                };
-                // TODO: what about i18n ?
-                let folder_name = format!("My Folder - {}", owner_id_short);
-                match self
-                    .folder_storage
-                    .create_home_folder(caller_id, folder_name.clone())
-                    .await
-                {
-                    Ok(home_folder) => {
-                        tracing::info!(
-                            "Created home folder '{}' for user {}",
-                            folder_name,
-                            caller_id
-                        );
-                        return Ok(vec![FolderDto::from(home_folder)]);
-                    }
-                    Err(e) => {
-                        tracing::warn!(
-                            "Failed to create home folder for user {}: {}",
-                            caller_id,
-                            e
-                        );
-                        // Return empty list rather than failing - user might not have storage quota, etc.
-                    }
-                }
-            }
-            Ok(folders.into_iter().map(FolderDto::from).collect())
         }
+        // No parent → list the user's root folders.
+        let folders = self
+            .folder_storage
+            .list_folders_by_owner(parent_id, caller_id)
+            .await
+            .map_err(|e| {
+                DomainError::internal_error(
+                    "FolderStorage",
+                    format!(
+                        "Failed to list folders for owner '{}' in parent {:?}: {}",
+                        caller_id, parent_id, e
+                    ),
+                )
+            })?;
+        Ok(folders.into_iter().map(FolderDto::from).collect())
     }
-    // TODO: move self healing in other part (on account creation on or login ?)
 
     /// Lists folders with pagination
     async fn list_folders_paginated(
@@ -637,6 +603,59 @@ impl FolderService {
 
         Ok((rows, next_cursor))
     }
+
+    /// Idempotently provision a home folder for a user.
+    ///
+    /// Returns `Ok(true)` if a folder was newly created, `Ok(false)` if the
+    /// user already had at least one root folder.
+    ///
+    /// **System-level operation** — bypasses authz because this runs on
+    /// the user's own behalf (during creation or login provisioning) at a
+    /// point where the caller may be the engine itself, not an HTTP user.
+    /// Callers must be inside trusted code paths (lifecycle hooks).
+    ///
+    /// Used by [`HomeFolderLifecycleHook`] on `on_user_created` and
+    /// `on_user_login`. Replaces the old self-heal at the listing path
+    /// and the four eager `create_personal_folder` calls in
+    /// `AuthApplicationService` (removed in the same PR).
+    pub async fn ensure_home_folder(
+        &self,
+        user_id: Uuid,
+        username: &str,
+    ) -> Result<bool, DomainError> {
+        let existing = self
+            .folder_storage
+            .list_folders_by_owner(None, user_id)
+            .await
+            .map_err(|e| {
+                DomainError::internal_error(
+                    "FolderStorage",
+                    format!("ensure_home_folder: list root folders: {}", e),
+                )
+            })?;
+        if !existing.is_empty() {
+            return Ok(false);
+        }
+
+        let folder_name = format!("My Folder - {}", username);
+        self.folder_storage
+            .create_home_folder(user_id, folder_name.clone())
+            .await
+            .map_err(|e| {
+                DomainError::internal_error(
+                    "FolderStorage",
+                    format!("ensure_home_folder: create: {}", e),
+                )
+            })?;
+        tracing::info!(
+            target: "user_lifecycle",
+            hook = "home_folder",
+            user_id = %user_id,
+            folder_name = %folder_name,
+            "Home folder provisioned"
+        );
+        Ok(true)
+    }
 }
 
 /// Build the next-page cursor from the last row of the current page.
@@ -690,3 +709,100 @@ fn build_folder_resource_cursor(
         },
     }
 }
+
+// ─────────────────────────────────────────────────────────────────────────────
+// HomeFolderLifecycleHook
+//
+// Owns home-folder provisioning policy. Replaces:
+//   - the 4 eager `create_personal_folder` calls in AuthApplicationService
+//     (register / setup_create_admin / admin_create_user / OIDC JIT)
+//   - the self-heal at `list_folders_with_perms` when no root folders exist
+//
+// Lives in this file (not under a centralised `lifecycle/` directory)
+// because the folder service owns home-folder policy — see the
+// "owner-located convention" note in
+// `docs/architecture/user-lifecycle.md`.
+// ─────────────────────────────────────────────────────────────────────────────
+
+use async_trait::async_trait;
+
+use crate::application::ports::user_lifecycle::{DeletionMode, LogoutReason, UserLifecycleHook};
+use crate::domain::entities::user::User;
+
+/// Lifecycle hook: provisions and (in PR 4) deprovisions a user's home folder.
+pub struct HomeFolderLifecycleHook {
+    folder_service: Arc<FolderService>,
+}
+
+impl HomeFolderLifecycleHook {
+    pub fn new(folder_service: Arc<FolderService>) -> Self {
+        Self { folder_service }
+    }
+
+    /// Idempotent provisioning shared by `on_user_created` and
+    /// `on_user_login`. External users are skipped per tip #2 in the
+    /// trait docstring.
+    async fn provision_if_needed(&self, user: &User) -> Result<(), DomainError> {
+        if user.is_external() {
+            return Ok(());
+        }
+        // `ensure_home_folder` handles the "does the user already have a
+        // root folder?" check internally and is a no-op if so.
+        self.folder_service
+            .ensure_home_folder(user.id(), user.username())
+            .await
+            .map(|_created| ())
+    }
+}
+
+#[async_trait]
+impl UserLifecycleHook for HomeFolderLifecycleHook {
+    fn name(&self) -> &'static str {
+        "home_folder"
+    }
+
+    async fn on_user_created(&self, user: &User) -> Result<(), DomainError> {
+        self.provision_if_needed(user).await
+    }
+
+    /// Login is the safety net — if `on_user_created` failed at any
+    /// earlier point (or the user was created in a flow that pre-dated
+    /// this hook), provisioning happens here on next login.
+    async fn on_user_login(&self, user: &User) -> Result<(), DomainError> {
+        self.provision_if_needed(user).await
+    }
+
+    async fn on_user_logout(&self, _user: &User, _reason: LogoutReason) -> Result<(), DomainError> {
+        // Folders don't react to logout. Explicit no-op per the
+        // "no defaults" convention.
+        Ok(())
+    }
+
+    async fn on_user_deleted(
+        &self,
+        user: &User,
+        mode: DeletionMode,
+        _tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
+    ) -> Result<(), DomainError> {
+        // For both DeletionMode variants today the FK CASCADE on
+        // `storage.folders.user_id` (and downstream files/blobs)
+        // removes the home folder + contents when the user row goes.
+        // The hook emits a per-mode tracing event so audit can tell
+        // AdminDelete (currently recoverable only via DB-level rollback
+        // before commit) from GdprPurge (no sweeper exists yet — the
+        // variant is reserved for a future PR that adds retention).
+        //
+        // The `tx` is provided per the trait contract but unused here:
+        // emitting a tracing event doesn't require DB access. Future
+        // policy (trash with retention) would write to `storage.trash`
+        // inside this same tx.
+        tracing::info!(
+            target: "user_lifecycle",
+            hook = "home_folder",
+            user_id = %user.id(),
+            mode = ?mode,
+            "Home folder will be removed via FK CASCADE on user delete"
+        );
+        Ok(())
+    }
+}

src/application/services/mod.rs

@@ -6,6 +6,7 @@ pub mod blob_lifecycle_service;
 pub mod calendar_service;
 pub mod contact_service;
 pub mod device_auth_service;
+pub mod external_identity_service;
 pub mod favorites_service;
 pub mod file_lifecycle_service;
 pub mod file_management_service;
@@ -25,6 +26,7 @@ pub mod storage_settings_service;
 pub mod storage_usage_service;
 pub mod subject_group_service;
 pub mod trash_service;
+pub mod user_lifecycle_service;
 pub mod wopi_lock_service;
 pub mod wopi_token_service;
 

src/application/services/user_lifecycle_service.rs

@@ -0,0 +1,281 @@
+//! User-lifecycle dispatcher + the always-on `AuditLifecycleHook`.
+//!
+//! [`UserLifecycleService`] aggregates every registered
+//! [`UserLifecycleHook`] and fans out each lifecycle event with
+//! per-event failure semantics. See `user_lifecycle.rs` for the trait
+//! contract and tips for implementors.
+//!
+//! [`AuditLifecycleHook`] lives in this file (not under
+//! `infrastructure/services/`) because it's cross-cutting — no domain
+//! service owns "user-lifecycle audit", and the hook is small enough that
+//! a separate module would be ceremony. Every other hook lives with the
+//! service that owns its work (see `architecture/user-lifecycle.md`).
+
+use std::sync::Arc;
+
+use async_trait::async_trait;
+
+use crate::application::ports::user_lifecycle::{DeletionMode, LogoutReason, UserLifecycleHook};
+use crate::common::errors::DomainError;
+use crate::domain::entities::user::User;
+
+/// Composite dispatcher for user-lifecycle events.
+///
+/// Mirrors the [`FileLifecycleService`] shape: a `Vec<Arc<dyn ...>>` and a
+/// builder. The per-event failure semantics differ from the file-side
+/// (file events are sync fire-and-forget; user events have per-method
+/// rules — see the trait docstring).
+pub struct UserLifecycleService {
+    hooks: Vec<Arc<dyn UserLifecycleHook>>,
+}
+
+impl Default for UserLifecycleService {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl UserLifecycleService {
+    pub fn new() -> Self {
+        Self { hooks: Vec::new() }
+    }
+
+    pub fn with_hook(mut self, hook: Arc<dyn UserLifecycleHook>) -> Self {
+        self.hooks.push(hook);
+        self
+    }
+
+    /// Created: log-and-continue. If a hook returns `Err`, the user is
+    /// still created — the next login's `on_user_login` will retry
+    /// idempotently. See tip #6 in the trait docstring.
+    pub async fn dispatch_created(&self, user: &User) {
+        for h in &self.hooks {
+            if let Err(e) = h.on_user_created(user).await {
+                tracing::error!(
+                    target: "user_lifecycle",
+                    hook = h.name(),
+                    user_id = %user.id(),
+                    error = %e,
+                    "on_user_created failed; will retry on next login"
+                );
+            }
+        }
+    }
+
+    /// Login: log-and-continue. Same reasoning as `dispatch_created`.
+    /// Must fire BEFORE `user.register_login()` so that hooks observing
+    /// `last_login_at().is_none()` correctly detect the first-ever login.
+    pub async fn dispatch_login(&self, user: &User) {
+        for h in &self.hooks {
+            if let Err(e) = h.on_user_login(user).await {
+                tracing::error!(
+                    target: "user_lifecycle",
+                    hook = h.name(),
+                    user_id = %user.id(),
+                    error = %e,
+                    "on_user_login failed; will retry on next login"
+                );
+            }
+        }
+    }
+
+    /// Logout: fire-and-forget. Spawned so the HTTP response doesn't wait
+    /// for downstream cache flushes. Takes ownership of `User` because the
+    /// spawn outlives the caller's borrow.
+    pub fn dispatch_logout(&self, user: User, reason: LogoutReason) {
+        let hooks = self.hooks.clone();
+        tokio::spawn(async move {
+            for h in &hooks {
+                if let Err(e) = h.on_user_logout(&user, reason).await {
+                    tracing::error!(
+                        target: "user_lifecycle",
+                        hook = h.name(),
+                        reason = ?reason,
+                        user_id = %user.id(),
+                        error = %e,
+                        "on_user_logout failed"
+                    );
+                }
+            }
+        });
+    }
+
+    /// Deleted: runs inside the `delete_user_admin` transaction. First
+    /// `Err` propagates and aborts the transaction — the user is NOT
+    /// deleted. Hooks must keep their cleanup conservative. See tip #7
+    /// in the trait docstring.
+    pub async fn dispatch_deleted(
+        &self,
+        user: &User,
+        mode: DeletionMode,
+        tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
+    ) -> Result<(), DomainError> {
+        for h in &self.hooks {
+            if let Err(e) = h.on_user_deleted(user, mode, tx).await {
+                tracing::error!(
+                    target: "user_lifecycle",
+                    hook = h.name(),
+                    mode = ?mode,
+                    user_id = %user.id(),
+                    error = %e,
+                    "on_user_deleted failed — aborting transaction"
+                );
+                return Err(e);
+            }
+        }
+        Ok(())
+    }
+}
+
+// ─────────────────────────────────────────────────────────────────────────────
+// AuditLifecycleHook
+//
+// Always-on observer. Emits one structured `tracing::info!(target: "audit",
+// ...)` line per event. The only hook registered in PR 1; subsequent PRs
+// add HomeFolderLifecycleHook, AuthzCacheLifecycleHook, etc., each living
+// next to the service it works for.
+// ─────────────────────────────────────────────────────────────────────────────
+
+/// Cross-cutting audit observer for user-lifecycle events. Co-located with
+/// the dispatcher because audit has no domain owner.
+pub struct AuditLifecycleHook;
+
+#[async_trait]
+impl UserLifecycleHook for AuditLifecycleHook {
+    fn name(&self) -> &'static str {
+        "audit"
+    }
+
+    async fn on_user_created(&self, user: &User) -> Result<(), DomainError> {
+        tracing::info!(
+            target: "audit",
+            event = "user.created",
+            user_id = %user.id(),
+            username = %user.username(),
+            is_external = user.is_external(),
+        );
+        Ok(())
+    }
+
+    async fn on_user_login(&self, user: &User) -> Result<(), DomainError> {
+        tracing::info!(
+            target: "audit",
+            event = "user.login",
+            user_id = %user.id(),
+            username = %user.username(),
+            is_external = user.is_external(),
+            first_login = user.last_login_at().is_none(),
+        );
+        Ok(())
+    }
+
+    async fn on_user_logout(&self, user: &User, reason: LogoutReason) -> Result<(), DomainError> {
+        tracing::info!(
+            target: "audit",
+            event = "user.logout",
+            user_id = %user.id(),
+            username = %user.username(),
+            is_external = user.is_external(),
+            reason = ?reason,
+        );
+        Ok(())
+    }
+
+    async fn on_user_deleted(
+        &self,
+        user: &User,
+        mode: DeletionMode,
+        _tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
+    ) -> Result<(), DomainError> {
+        // Audit hook doesn't write to the DB — only emits a tracing
+        // event. The `_tx` is intentionally ignored.
+        tracing::info!(
+            target: "audit",
+            event = "user.deleted",
+            user_id = %user.id(),
+            username = %user.username(),
+            is_external = user.is_external(),
+            mode = ?mode,
+        );
+        Ok(())
+    }
+}
+
+// ─────────────────────────────────────────────────────────────────────────────
+// SessionRevocationLifecycleHook
+//
+// Replaces the silent FK CASCADE on `auth.sessions.user_id` with an
+// explicit `revoke_all_user_sessions` call inside the delete transaction
+// — emits an aggregate audit event ("user.sessions_revoked_on_delete,
+// count=N") so the deletion of N sessions is observable, instead of N
+// rows quietly vanishing via CASCADE.
+//
+// Co-located with the dispatcher because there is no dedicated session
+// service today; the session-storage port is the only consumer. If a
+// `SessionService` ever emerges, this hook moves there.
+// ─────────────────────────────────────────────────────────────────────────────
+
+use crate::application::ports::auth_ports::SessionStoragePort;
+use crate::infrastructure::repositories::pg::SessionPgRepository;
+
+/// Lifecycle hook: explicit per-user session revocation on delete with
+/// audit trail. On any other event: explicit no-op.
+pub struct SessionRevocationLifecycleHook {
+    session_storage: Arc<SessionPgRepository>,
+}
+
+impl SessionRevocationLifecycleHook {
+    pub fn new(session_storage: Arc<SessionPgRepository>) -> Self {
+        Self { session_storage }
+    }
+}
+
+#[async_trait]
+impl UserLifecycleHook for SessionRevocationLifecycleHook {
+    fn name(&self) -> &'static str {
+        "session_revocation"
+    }
+
+    async fn on_user_created(&self, _user: &User) -> Result<(), DomainError> {
+        Ok(())
+    }
+
+    async fn on_user_login(&self, _user: &User) -> Result<(), DomainError> {
+        Ok(())
+    }
+
+    async fn on_user_logout(&self, _user: &User, _reason: LogoutReason) -> Result<(), DomainError> {
+        // The session causing this logout has already been revoked by
+        // the caller (logout / change_password / etc.). Nothing for this
+        // hook to do.
+        Ok(())
+    }
+
+    async fn on_user_deleted(
+        &self,
+        user: &User,
+        mode: DeletionMode,
+        _tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
+    ) -> Result<(), DomainError> {
+        // NOTE on `_tx`: ideally this would use the transaction so the
+        // session revocation is atomic with the user DELETE. The current
+        // SessionStoragePort surface doesn't expose a tx-accepting
+        // variant of `revoke_all_user_sessions`, so we revoke against
+        // the same pool. The FK CASCADE on `auth.sessions.user_id`
+        // would clean up any sessions left behind by a rollback anyway,
+        // so the safety net holds.
+        let count = self
+            .session_storage
+            .revoke_all_user_sessions(user.id())
+            .await?;
+        tracing::info!(
+            target: "audit",
+            event = "user.sessions_revoked_on_delete",
+            user_id = %user.id(),
+            username = %user.username(),
+            mode = ?mode,
+            count = count,
+        );
+        Ok(())
+    }
+}

src/common/di.rs

@@ -691,12 +691,71 @@ impl AppServiceFactory {
             storage_usage_service =
                 Some(self.create_storage_usage_service(&repos, &pool, &maintenance_pool));
 
-            // Auth services
+            // User-lifecycle dispatcher. Hook order is registration order;
+            // document dependencies inline if/when any arise. Today:
+            //   1. AuditLifecycleHook             — fires first so the
+            //                                       audit event is recorded
+            //                                       even if a later hook
+            //                                       errors out.
+            //   2. HomeFolderLifecycleHook        — provisions the user's
+            //                                       home folder on
+            //                                       created/login (no-op
+            //                                       for external users).
+            //   3. AuthzCacheLifecycleHook        — invalidates the
+            //                                       Moka group-expansion
+            //                                       cache on logout/delete
+            //                                       so a re-login sees fresh
+            //                                       membership immediately.
+            //   4. SessionRevocationLifecycleHook — explicit per-user
+            //                                       session revocation on
+            //                                       delete (with audit) —
+            //                                       replaces the silent FK
+            //                                       CASCADE.
+            //   5. ExternalIdentityLifecycleHook  — STUB. No-op for every
+            //                                       event today; the
+            //                                       magic-link / OIDC-only /
+            //                                       OCM PR will fill it in
+            //                                       to populate
+            //                                       `auth.user_external_identity`.
+            //                                       Last in the chain so it
+            //                                       observes the latest user
+            //                                       state before the chain
+            //                                       commits.
+            let session_repo_for_hook = Arc::new(SessionPgRepository::new(pool.clone()));
+            let user_lifecycle = Arc::new(
+                crate::application::services::user_lifecycle_service::UserLifecycleService::new()
+                    .with_hook(Arc::new(
+                        crate::application::services::user_lifecycle_service::AuditLifecycleHook,
+                    ))
+                    .with_hook(Arc::new(
+                        crate::application::services::folder_service::HomeFolderLifecycleHook::new(
+                            apps.folder_service_concrete.clone(),
+                        ),
+                    ))
+                    .with_hook(Arc::new(
+                        crate::infrastructure::services::pg_acl_engine::AuthzCacheLifecycleHook::new(
+                            authorization.clone(),
+                        ),
+                    ))
+                    .with_hook(Arc::new(
+                        crate::application::services::user_lifecycle_service::SessionRevocationLifecycleHook::new(
+                            session_repo_for_hook,
+                        ),
+                    ))
+                    .with_hook(Arc::new(
+                        crate::application::services::external_identity_service::ExternalIdentityLifecycleHook,
+                    )),
+            );
+
+            // Auth services. Folder service no longer threaded here —
+            // PR 3 moved home-folder provisioning into
+            // HomeFolderLifecycleHook, which already holds an Arc to the
+            // folder service via the user_lifecycle dispatcher.
             if self.config.features.enable_auth {
                 let services = crate::infrastructure::auth_factory::create_auth_services(
                     &self.config,
                     pool.clone(),
-                    Some(apps.folder_service_concrete.clone()),
+                    user_lifecycle.clone(),
                 )
                 .await
                 .map_err(|e| {

src/domain/entities/user.rs

@@ -36,6 +36,13 @@ pub struct User {
     oidc_provider: Option<String>,
     oidc_subject: Option<String>,
     image: Option<String>,
+    /// TRUE = grant-only external recipient (magic-link, OIDC-only, OCM
+    /// federated). FALSE = storage-owning internal user. Hooks that
+    /// provision per-user resources (home folder, default calendar, …)
+    /// must short-circuit when `is_external` is TRUE — see tip #2 in
+    /// `application/ports/user_lifecycle.rs`. The DB CHECK constraint
+    /// `users_external_no_storage` is the schema-level safety net.
+    is_external: bool,
 }
 
 impl User {
@@ -85,6 +92,7 @@ impl User {
             oidc_provider: None,
             oidc_subject: None,
             image: None,
+            is_external: false,
         })
     }
 
@@ -115,6 +123,48 @@ impl User {
             oidc_provider: Some(oidc_provider),
             oidc_subject: Some(oidc_subject),
             image: None,
+            is_external: false,
+        })
+    }
+
+    /// Create a new external user — magic-link / OIDC-only / OCM-federated
+    /// recipient who does NOT own storage. The `CHECK (NOT is_external OR
+    /// storage_used_bytes = 0)` DB constraint enforces the no-storage rule
+    /// at the schema level.
+    ///
+    /// **External users are always `UserRole::User`** — there is no role
+    /// parameter because admin + external is an explicitly forbidden
+    /// combination enforced by the `users_external_not_admin` DB CHECK
+    /// constraint. Granting admin to a federated principal would let
+    /// external identity providers indirectly manage the local instance.
+    /// To make an external user an admin: first convert them to internal
+    /// (`UPDATE auth.users SET is_external = FALSE`), then update role.
+    /// The two-step process is intentional friction.
+    ///
+    /// Quota is set to 0 because external users can't upload content
+    /// into any folder they own (they have no folder). They can only
+    /// act on grants the resource owner provides — which counts against
+    /// the owner's quota, not theirs.
+    pub fn new_external(username: String, email: String) -> UserResult<Self> {
+        Self::validate_username(&username)?;
+        Self::validate_email(&email)?;
+        let now = Utc::now();
+        Ok(Self {
+            id: Uuid::new_v4(),
+            username,
+            email,
+            password_hash: "__EXTERNAL_NO_PASSWORD__".to_string(),
+            role: UserRole::User,
+            storage_quota_bytes: 0,
+            storage_used_bytes: 0,
+            created_at: now,
+            updated_at: now,
+            last_login_at: None,
+            active: true,
+            oidc_provider: None,
+            oidc_subject: None,
+            image: None,
+            is_external: true,
         })
     }
 
@@ -147,6 +197,13 @@ impl User {
             oidc_provider: None,
             oidc_subject: None,
             image: None,
+            // `from_data` is the minimal-args reconstruction path used by
+            // tests and JWT-claim-based principal hydration (which doesn't
+            // carry `is_external`). Default to FALSE — JWT-validated
+            // principals are existing internal users; magic-link external
+            // sessions take a different path that hydrates from DB via
+            // `from_data_full`.
+            is_external: false,
         }
     }
 
@@ -166,6 +223,7 @@ impl User {
         oidc_provider: Option<String>,
         oidc_subject: Option<String>,
         image: Option<String>,
+        is_external: bool,
     ) -> Self {
         Self {
             id,
@@ -182,6 +240,7 @@ impl User {
             oidc_provider,
             oidc_subject,
             image,
+            is_external,
         }
     }
 
@@ -242,6 +301,14 @@ impl User {
         self.image.as_deref()
     }
 
+    /// `TRUE` for grant-only external recipients (magic-link, OIDC-only,
+    /// OCM federated). Hooks provisioning per-user resources must
+    /// short-circuit when this returns `true` — see tip #2 in
+    /// `application/ports/user_lifecycle.rs`.
+    pub fn is_external(&self) -> bool {
+        self.is_external
+    }
+
     pub fn set_image(&mut self, image: Option<String>) {
         self.image = image;
         self.updated_at = Utc::now();

src/infrastructure/auth_factory.rs

@@ -4,7 +4,7 @@ use std::sync::Arc;
 type Result<T> = std::result::Result<T, Box<dyn std::error::Error + Send + Sync>>;
 
 use crate::application::services::auth_application_service::AuthApplicationService;
-use crate::application::services::folder_service::FolderService;
+use crate::application::services::user_lifecycle_service::UserLifecycleService;
 use crate::common::config::AppConfig;
 use crate::common::di::AuthServices;
 use crate::infrastructure::repositories::{SessionPgRepository, UserPgRepository};
@@ -15,7 +15,7 @@ use crate::infrastructure::services::password_hasher::Argon2PasswordHasher;
 pub async fn create_auth_services(
     config: &AppConfig,
     pool: Arc<PgPool>,
-    folder_service: Option<Arc<FolderService>>,
+    user_lifecycle: Arc<UserLifecycleService>,
 ) -> Result<AuthServices> {
     // Create JWT token service (TokenServicePort implementation)
     let token_service: Arc<JwtTokenService> = Arc::new(JwtTokenService::new(
@@ -44,10 +44,11 @@ pub async fn create_auth_services(
         config.storage_path.clone(),
     );
 
-    // Configure folder service if available
+    // Wire the user-lifecycle dispatcher. Home-folder provisioning is
-    if let Some(folder_svc) = folder_service {
+    // now handled by HomeFolderLifecycleHook (registered on the
-        auth_app_service = auth_app_service.with_folder_service(folder_svc);
+    // dispatcher in DI) — AuthApplicationService no longer needs a
-    }
+    // direct FolderService dependency for that path.
+    auth_app_service = auth_app_service.with_user_lifecycle(user_lifecycle);
 
     // Configure OIDC service if enabled
     if config.oidc.enabled {

src/infrastructure/repositories/pg/user_pg_repository.rs

@@ -27,6 +27,14 @@ impl UserPgRepository {
         Self { pool }
     }
 
+    /// Borrowed access to the connection pool. Exposed so callers can
+    /// open transactions that span this repo and other repos / hooks
+    /// (e.g. `AuthApplicationService::delete_user_admin` opening a tx
+    /// that wraps the lifecycle dispatcher + the DELETE).
+    pub fn pool(&self) -> &PgPool {
+        &self.pool
+    }
+
     // Helper method to map SQL errors to domain errors
     pub fn map_sqlx_error(err: sqlx::Error) -> UserRepositoryError {
         match err {
@@ -84,13 +92,13 @@ impl UserRepository for UserPgRepository {
                 let _result = sqlx::query(
                     r#"
                         INSERT INTO auth.users (
-                            id, username, email, password_hash, role, 
+                            id, username, email, password_hash, role,
-                            storage_quota_bytes, storage_used_bytes, 
+                            storage_quota_bytes, storage_used_bytes,
                             created_at, updated_at, last_login_at, active,
-                            oidc_provider, oidc_subject
+                            oidc_provider, oidc_subject, is_external
                         ) VALUES (
                             $1, $2, $3, $4, $5::auth.userrole, $6, $7, $8, $9, $10, $11,
-                            $12, $13
+                            $12, $13, $14
                         )
                         RETURNING *
                         "#,
@@ -108,6 +116,7 @@ impl UserRepository for UserPgRepository {
                 .bind(user_clone.is_active())
                 .bind(user_clone.oidc_provider())
                 .bind(user_clone.oidc_subject())
+                .bind(user_clone.is_external())
                 .execute(&mut **tx)
                 .await
                 .map_err(Self::map_sqlx_error)?;
@@ -131,7 +140,7 @@ impl UserRepository for UserPgRepository {
                 id, username, email, password_hash, role::text as role_text,
                 storage_quota_bytes, storage_used_bytes,
                 created_at, updated_at, last_login_at, active,
-                oidc_provider, oidc_subject, image
+                oidc_provider, oidc_subject, image, is_external
             FROM auth.users
             WHERE id = $1
             "#,
@@ -163,6 +172,7 @@ impl UserRepository for UserPgRepository {
             row.get("oidc_provider"),
             row.get("oidc_subject"),
             row.get("image"),
+            row.get("is_external"),
         ))
     }
 
@@ -174,7 +184,7 @@ impl UserRepository for UserPgRepository {
                 id, username, email, password_hash, role::text as role_text,
                 storage_quota_bytes, storage_used_bytes,
                 created_at, updated_at, last_login_at, active,
-                oidc_provider, oidc_subject, image
+                oidc_provider, oidc_subject, image, is_external
             FROM auth.users
             WHERE username = $1
             "#,
@@ -206,6 +216,7 @@ impl UserRepository for UserPgRepository {
             row.get("oidc_provider"),
             row.get("oidc_subject"),
             row.get("image"),
+            row.get("is_external"),
         ))
     }
 
@@ -217,7 +228,7 @@ impl UserRepository for UserPgRepository {
                 id, username, email, password_hash, role::text as role_text,
                 storage_quota_bytes, storage_used_bytes,
                 created_at, updated_at, last_login_at, active,
-                oidc_provider, oidc_subject, image
+                oidc_provider, oidc_subject, image, is_external
             FROM auth.users
             WHERE email = $1
             "#,
@@ -249,6 +260,7 @@ impl UserRepository for UserPgRepository {
             row.get("oidc_provider"),
             row.get("oidc_subject"),
             row.get("image"),
+            row.get("is_external"),
         ))
     }
 
@@ -354,7 +366,7 @@ impl UserRepository for UserPgRepository {
                 id, username, email, password_hash, role::text as role_text,
                 storage_quota_bytes, storage_used_bytes,
                 created_at, updated_at, last_login_at, active,
-                oidc_provider, oidc_subject, image
+                oidc_provider, oidc_subject, image, is_external
             FROM auth.users
             ORDER BY created_at DESC
             LIMIT $1 OFFSET $2
@@ -391,6 +403,7 @@ impl UserRepository for UserPgRepository {
                     row.get("oidc_provider"),
                     row.get("oidc_subject"),
                     row.get("image"),
+                    row.get("is_external"),
                 )
             })
             .collect();
@@ -406,7 +419,7 @@ impl UserRepository for UserPgRepository {
                 id, username, email, password_hash, role::text as role_text,
                 storage_quota_bytes, storage_used_bytes,
                 created_at, updated_at, last_login_at, active,
-                oidc_provider, oidc_subject, image
+                oidc_provider, oidc_subject, image, is_external
             FROM auth.users
             WHERE username ILIKE $1 OR email ILIKE $1
             ORDER BY username
@@ -443,6 +456,7 @@ impl UserRepository for UserPgRepository {
                     row.get("oidc_provider"),
                     row.get("oidc_subject"),
                     row.get("image"),
+                    row.get("is_external"),
                 )
             })
             .collect();
@@ -529,7 +543,7 @@ impl UserRepository for UserPgRepository {
                 id, username, email, password_hash, role::text as role_text,
                 storage_quota_bytes, storage_used_bytes,
                 created_at, updated_at, last_login_at, active,
-                oidc_provider, oidc_subject, image
+                oidc_provider, oidc_subject, image, is_external
             FROM auth.users
             WHERE role::text = $1
             ORDER BY created_at DESC
@@ -565,6 +579,7 @@ impl UserRepository for UserPgRepository {
                     row.get("oidc_provider"),
                     row.get("oidc_subject"),
                     row.get("image"),
+                    row.get("is_external"),
                 )
             })
             .collect();
@@ -600,7 +615,7 @@ impl UserRepository for UserPgRepository {
                 id, username, email, password_hash, role::text as role_text,
                 storage_quota_bytes, storage_used_bytes,
                 created_at, updated_at, last_login_at, active,
-                oidc_provider, oidc_subject, image
+                oidc_provider, oidc_subject, image, is_external
             FROM auth.users
             WHERE oidc_provider = $1 AND oidc_subject = $2
             "#,
@@ -632,6 +647,7 @@ impl UserRepository for UserPgRepository {
             row.get("oidc_provider"),
             row.get("oidc_subject"),
             row.get("image"),
+            row.get("is_external"),
         ))
     }
 

src/infrastructure/services/pg_acl_engine.rs

@@ -114,6 +114,17 @@ impl PgAclEngine {
         }
     }
 
+    /// Drop the cached transitive-group expansion for one user, forcing
+    /// the next `expand_user(uid)` to walk the recursive CTE again.
+    ///
+    /// Called by [`AuthzCacheLifecycleHook`] on `on_user_logout` /
+    /// `on_user_deleted` so a re-login (or a re-created account with the
+    /// same id) doesn't observe stale memberships during the 30 s TTL
+    /// window. Cheap — moka's `invalidate` is a single concurrent-map op.
+    pub async fn invalidate_user_groups_cache(&self, user_id: Uuid) {
+        self.user_groups_cache.invalidate(&user_id).await;
+    }
+
     /// Expand a user subject into the set of subject UUIDs that should match
     /// in `access_grants`: the user's own UUID, every group the user is
     /// transitively a member of, and the implicit `INTERNAL_GROUP_ID`.
@@ -1590,3 +1601,72 @@ impl AuthorizationEngine for PgAclEngine {
         Ok(result.rows_affected() as usize)
     }
 }
+
+// ─────────────────────────────────────────────────────────────────────────────
+// AuthzCacheLifecycleHook
+//
+// Owns invalidation of the `user_groups_cache` Moka entry when a user's
+// state changes in ways that affect transitive-group expansion (logout
+// — so a re-login with new group memberships doesn't observe a stale
+// expansion during the 30 s TTL window; delete — so a re-created
+// account with the same id doesn't inherit the old cached value).
+//
+// Lives in this file (not under a centralised `lifecycle/` directory)
+// because the authz engine owns its own cache invariants. See the
+// "owner-located convention" note in
+// `docs/architecture/user-lifecycle.md`.
+// ─────────────────────────────────────────────────────────────────────────────
+
+use async_trait::async_trait;
+
+use crate::application::ports::user_lifecycle::{DeletionMode, LogoutReason, UserLifecycleHook};
+use crate::domain::entities::user::User;
+
+/// Lifecycle hook: drops the `user_groups_cache` entry for one user on
+/// logout / deletion so the next authz check rebuilds it from current
+/// `subject_group_members` rows.
+pub struct AuthzCacheLifecycleHook {
+    engine: Arc<PgAclEngine>,
+}
+
+impl AuthzCacheLifecycleHook {
+    pub fn new(engine: Arc<PgAclEngine>) -> Self {
+        Self { engine }
+    }
+}
+
+#[async_trait]
+impl UserLifecycleHook for AuthzCacheLifecycleHook {
+    fn name(&self) -> &'static str {
+        "authz_cache"
+    }
+
+    async fn on_user_created(&self, _user: &User) -> Result<(), DomainError> {
+        // New user can't have a stale cache entry (no prior `expand_user`
+        // call has produced one). Explicit no-op per the trait convention.
+        Ok(())
+    }
+
+    async fn on_user_login(&self, _user: &User) -> Result<(), DomainError> {
+        // Login doesn't change group membership; the cache (if present)
+        // is still correct.
+        Ok(())
+    }
+
+    async fn on_user_logout(&self, user: &User, _reason: LogoutReason) -> Result<(), DomainError> {
+        self.engine.invalidate_user_groups_cache(user.id()).await;
+        Ok(())
+    }
+
+    async fn on_user_deleted(
+        &self,
+        user: &User,
+        _mode: DeletionMode,
+        _tx: &mut sqlx::Transaction<'_, sqlx::Postgres>,
+    ) -> Result<(), DomainError> {
+        // No DB writes here — just memory invalidation. `_tx` is
+        // intentionally ignored.
+        self.engine.invalidate_user_groups_cache(user.id()).await;
+        Ok(())
+    }
+}