v0.189.0 — desired state + the app-stop crash marker (R-166 / D-b)

The box stops inferring the customer's intent from a container count and reads
what they actually asked for.

Part 1 — desired state. AppConfig gains a tri-state `desired_state`
(""/running/stopped), written ONLY by the customer's own action: the API action
switch, DeployStack, UpdateOptionalConfig's redeploy branch, and the .fab
import. Intent is written BEFORE the act and a failed write REFUSES the act.
StartStack/StopStack are deliberately not writers — 14 callers, only 2 are the
customer. bootrecon.isBootOrphan now reads intent instead of len(Containers)>0,
which closes R-157 mechanism B (a power cut or interrupted deploy left an app
with zero containers, read as a deliberate stop, and stranded silently).

ABSENT MEANS UNKNOWN, NEVER "running": every pre-v0.189.0 app.yaml reads absent,
so the legacy fallback is byte-identical to the old rule. A running-only startup
backfill converges the unambiguous cases; `stopped` is never inferred.

Part 2 — backup.AppStopGuard, a persisted marker over every stop→work→start
window (volume dump, offbox reconstitute, .fab export). Its own file, never
quiesce's. Written before the stop, cleared only after a restart that succeeded,
kept when one fails. Recover() completes before the boot reconciler is launched
and returns its outcome, which main.go reports on the existing backup_failed
event once the notifier exists. A defer is not the mechanism — a SIGKILL runs
none (Campaign 8 fault 10).

Also: SaveAppConfig rebuilt AppConfig field-by-field (the R-100 shape) and would
have dropped desired_state on every save across nine call sites. Replaced with
copy-and-overlay. Measured: app.yaml does not round-trip unknown YAML keys.

No hub change, no agent coupling, no user-visible string. 27/27 packages green;
7 red-proofs observed FAIL then restored.

REUSE.md

@@ -87,7 +87,9 @@
 | `Manager.PersistUnitRedeployConfig` (R-47, v0.153.0) | controller/internal/stacks/deploy.go | `(name, env map[string]string) error` | the PERSIST half of `RedeployFromEnv` — app.yaml + locked fields + in-memory flags, **starts nothing** | **TRAP: the restore paths must use THIS, never `RedeployFromEnv`.** RedeployFromEnv ends in a full `up -d`, which before the replay IS the H4 race. RedeployFromEnv is now literally this + the unchanged up-and-report tail |
 | `Manager.StartStackServices` (R-47, v0.153.0) | controller/internal/stacks/manager.go | `(name string, services []string) error` | scoped `compose up -d <svc>...` — the DB-only window a dump is replayed in | **REFUSES an empty list** (argument-less `up -d` is a FULL start — the one silent fall-through that would reintroduce the race). No `logPostStartStatus`: the app containers are absent on purpose. Never `RestartStack` here — it is a full up in disguise |
 | `appbackup.DBServiceNames` / `dbTypeForImage` (R-47, v0.153.0) | controller/internal/appbackup/dbservices.go | `(composePath string) ([]string, error)` | naming the compose SERVICE(s) holding a database, sorted | yaml.v3 `services:` MAP parse — **never a line scan** (immich's top-level `immich_ml_cache:` / `immich_postgres_data:` volume keys look exactly like services). `dbTypeForImage` is shared with `DiscoverDatabases`, which is what makes "a dump exists ⇒ a service can be named" hold. An error means CANNOT-TELL, never "no database" — callers refuse when a dump exists |
-| `Manager.StartStack/StopStack/RestartStack/UpdateStack` | controller/internal/stacks/manager.go | `(name string) error` | Lifecycle | Protected stacks refuse stop; all funnel through composeExec |
+| `Manager.StartStack/StopStack/RestartStack/UpdateStack` | controller/internal/stacks/manager.go | `(name string) error` | Lifecycle | Protected stacks refuse stop; all funnel through composeExec. **NOT writers of desired state (R-166)** — 14 call sites, only 2 are the customer; recording intent here would make a nightly backup indistinguishable from the customer pressing Stop. Use `SetDesiredState` at the intent point instead |
+| `Manager.SetDesiredState` / `DesiredStateOf` / `BackfillDesiredState` (R-166, v0.189.0) | controller/internal/stacks/desiredstate.go | `(name, desired string) error` / `(Stack) string` / `() int` | THE customer-intent record — `app.yaml` `desired_state`, tri-state `""`/`running`/`stopped` | **ONE OWNER: the customer's action.** Writers are the API action switch, `DeployStack`, `UpdateOptionalConfig`'s redeploy branch, and the `.fab` restore adapter — nothing else, ever. **`""` (absent) means UNKNOWN, never "running"**: every pre-v0.189.0 app.yaml reads absent, so treating it as running would start every deliberately-stopped app on upgrade. Write intent BEFORE the act and REFUSE the act if it fails (§8.2). Backfill is **running-only** — never infer `stopped` from zero containers, that inference IS the defect |
+| `backup.AppStopGuard` (`Begin`/`End`/`Recover`) (R-166, v0.189.0) | controller/internal/backup/appstop_marker.go | `(opID, reason, stacks) error` / `()` / `() *AppStopRecovery` | THE crash marker for stop→work→start windows (volume dump, offbox reconstitute, `.fab` export) | Its **own** file (`appstop-state.json`), never quiesce's — one file, one writer. **A `defer` is NOT the mechanism** (Campaign 8 fault 10: SIGKILL runs no defer); the marker is. Written BEFORE the stop, cleared ONLY after a restart that succeeded; a FAILED restart deliberately KEEPS it. `Recover` RETURNS its outcome rather than notifying, because it must complete before the boot reconciler while the notifier does not exist yet |
 | `Manager.DeleteStack` / `RemoveStack` | controller/internal/stacks/delete.go | `(name, removeHDDData[, backupPaths])` | THE guarded removal paths | Orphan/protected/deploying/running checks + ProtectedHDDPaths filter before any RemoveAll |
 | `resolveContainerState` / `aggregateState` | controller/internal/stacks/manager.go | `(dockerState, dockerStatus)` / `([]ContainerInfo)` | State classification | `.State` says "running" even when unhealthy — `.Status` parse is the fix |
 | `Manager.logPostStartStatus` | controller/internal/stacks/manager.go | `(name, stackDir, env)` | Async post-start verification | compose up exits 0 on crash-loops; this is the detection. Goroutine + 3s, never blocks |