Run compose like the terminal does, and follow changes made there (0.67.2)

StackPilot called `docker compose -p <folder> -f compose.yaml`, which is
not what `docker compose` typed in the stack's folder does. A
compose.override.yaml or a COMPOSE_FILE in .env applied in a terminal
and was dropped by the next Start in StackPilot, which recreated the
containers without it. A compose file's `name:` or a COMPOSE_PROJECT_NAME
in .env made the terminal's containers invisible: the stack showed as
stopped while running, and Start set up a second copy next to it.

Compose now runs in the stack's folder without -f, so it loads the same
files, and -p is the name compose itself picks there: COMPOSE_PROJECT_NAME
from .env, else the last `name:` among the compose files (${VAR} from
.env), else the folder name. A stack StackPilot already runs under its
folder name keeps that name while it has containers or volumes under it
and none under the declared one: switching would have brought it up
again on empty volumes. Backups record the project, and a restore takes
it from the files it has just put back.

Changes made outside StackPilot now reach every view:

- docker_watch_service reads Docker's events once for the backend. The
  dashboard rollup (cached 25s) and the stats cache are stale as soon as
  the event generation moves; the tiles followed a terminal `compose
  stop` after 15-30s, now within a second.
- Image events re-read the local digests, so a `docker compose pull` in
  a terminal clears the update badge instead of leaving it until the
  next registry check (an hour by default).
- The browser catches up when its event socket reconnects; what changed
  while it was down waited for the 60s poll.
- The stack detail carries a revision of the compose file and .env;
  saving after they changed on disk is refused with 409 and the editor
  offers to overwrite or to load the version on disk. A save used to
  replace a terminal edit without a word.
- A stack whose folder is gone is flagged "folder missing" instead of
  passing for an ordinary stopped stack.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Fx7gcuy8d6nPd95g43rGHu

backend/routers/stacks.py

@@ -151,6 +151,10 @@ def _stack_summary(
         "status": status,
         "service_count": total,
         "running_count": running,
+        # The folder is gone (removed in a terminal, a share not mounted): the
+        # row stays — its git source, schedules and settings are still here —
+        # but says so instead of passing for an ordinary stopped stack.
+        "missing": not os.path.isdir(compose_service.stack_dir(stack.id)),
         "created_at": stack.created_at,
         "updated_at": stack.updated_at,
     }
@@ -290,6 +294,7 @@ def get_stack(
         # What is holding the stack, so the page can offer to stop it instead
         # of only showing a spinner that never ends.
         "lock": _lock_view(lock, stack_id),
+        "missing": not os.path.isdir(compose_service.stack_dir(stack_id)),
         # Inline credentials masked for the read-only role, like the .env.
         "yaml": (
             compose_service.read_compose(stack_id)
@@ -300,6 +305,9 @@ def get_stack(
         # from the read-only role — same reasoning as the admin-only file
         # browser. Non-admins still get status, services and the compose file.
         "env": compose_service.read_env(stack_id) if user.role == "admin" else "",
+        # For the editor's save: see StackUpdate.base_revision. Admins only —
+        # it is a hash over the .env, which this role is not shown.
+        "revision": compose_service.stack_revision(stack_id) if user.role == "admin" else None,
         "containers": containers,
         "created_at": stack.created_at,
         "updated_at": stack.updated_at,
@@ -315,6 +323,18 @@ def update_stack(
     user: User = Depends(require_admin),
 ) -> dict:
     stack = _get_stack_or_404(session, stack_id)
+    if body.base_revision and (body.yaml is not None or body.env is not None):
+        current = compose_service.stack_revision(stack_id)
+        if current != body.base_revision:
+            raise HTTPException(
+                status_code=409,
+                detail={
+                    "error": "changed_on_disk",
+                    "detail": f"The compose file or .env of '{stack_id}' was changed outside "
+                    "StackPilot after it was opened here",
+                    "revision": current,
+                },
+            )
     if body.yaml is not None:
         compose_service.write_compose(stack_id, body.yaml)
     if body.env is not None:
@@ -341,7 +361,7 @@ def update_stack(
         session, user=user.username, action="stack.update", target=stack_id,
         ip=_client_ip(request),
     )
-    return _stack_summary(stack)
+    return {**_stack_summary(stack), "revision": compose_service.stack_revision(stack_id)}
 
 
 @router.delete("/{stack_id}")