feat: re-download outdated model weights as a cancellable batch

docs/v1-scope.md

@@ -77,7 +77,8 @@ Nothing else gates V1. When that sentence is true end to end, V1 is done.
 - **Model Manager outdated-weight cleanup, 2026-09-04:** although the Model
   Manager UI remains deferred, it gained the outdated-weight notice and
   `Delete outdated` as the agreed handling for a rembg namespace move (issue
-  #22). Bulk re-download is deliberately not part of it.
+  #22). Bulk re-download returned in #29 with confirmation, cancellation, batch
+  progress and per-model deletion after verification.
 
 ---
 

scripts/guardrails-baseline.json

@@ -20,7 +20,7 @@
     "long_functions": 2
   },
   "src/matteloop/jobs/models/session.py": {
-    "lines": 432,
+    "lines": 439,
     "long_functions": 1
   },
   "src/matteloop/jobs/render.py": {

src/matteloop/jobs/models/session.py

@@ -192,7 +192,12 @@ def prepare(self, model_id: str, extras: dict[str, object]) -> PreparationResult
             self._active_result = result
             return result
 
-    def fetch(self, model_id: str, progress: ProgressCallback | None = None) -> Path:
+    def fetch(
+        self,
+        model_id: str,
+        progress: ProgressCallback | None = None,
+        cancelled: CancellationCheck | None = None,
+    ) -> Path:
         """Download and verify one weight without starting a session for it.
 
         prepare() also launches the segmentation client, which is wrong for
@@ -209,7 +214,7 @@ def fetch(self, model_id: str, progress: ProgressCallback | None = None) -> Path
                 spec,
                 self._cache_root,
                 self._progress if progress is None else progress,
-                self._cancelled,
+                self._cancelled if cancelled is None else cancelled,
             )
 
     def remove(self, model_id: str) -> bool:
@@ -270,12 +275,14 @@ def remove(self, model_id: str) -> bool:
                 )
                 raise mapped from cause
 
-    def remove_obsolete_versions(self) -> int:
+    def remove_obsolete_versions(self, model_id: str | None = None) -> int:
         with self._lock:
             self._require_open()
             removed = 0
             for version in self._catalog.obsolete_rembg_versions:
                 version_path = self._cache_root / version
+                if model_id is not None:
+                    version_path = version_path / self._catalog.get(model_id).id
                 if not version_path.is_dir() or version_path.is_symlink():
                     continue
                 shutil.rmtree(version_path)