🐛 fix(models): track model availability

resources/matteloop_de.ts

@@ -30,7 +30,7 @@
         <translation>Original-Videobild</translation>
     </message>
     <message>
-        <location filename="../src/matteloop/ui/crop_canvas.py" line="333"/>
+        <location filename="../src/matteloop/ui/crop_canvas.py" line="344"/>
         <source>Crop bounds: x %s, y %s, width %s, height %s source pixels; source %s × %s</source>
         <translation>Zuschnittgrenzen: x %s, y %s, Breite %s, Höhe %s Quellpixel; Quelle %s × %s</translation>
     </message>
@@ -354,7 +354,7 @@
     <message>
         <location filename="../src/matteloop/ui/inspector.py" line="430"/>
         <source>%s — %s download required</source>
-        <translation>%s — %s Download erforderlich</translation>
+        <translation>Für %s ist ein Download von %s erforderlich</translation>
     </message>
     <message>
         <location filename="../src/matteloop/ui/inspector.py" line="465"/>
@@ -1124,7 +1124,7 @@ Freed %s.</source>
     <message>
         <location filename="../src/matteloop/ui/copy.py" line="367"/>
         <source>Download &amp; Preview</source>
-        <translation>Herunterladen &amp; Vorschau</translation>
+        <translation>Modell laden &amp; Vorschau</translation>
     </message>
     <message>
         <location filename="../src/matteloop/ui/copy.py" line="370"/>
@@ -1273,13 +1273,13 @@ Freed %s.</source>
         <translation>Video wird gerendert</translation>
     </message>
     <message>
-        <location filename="../src/matteloop/ui/preview_controller/controller.py" line="305"/>
+        <location filename="../src/matteloop/ui/preview_controller/controller.py" line="312"/>
         <location filename="../src/matteloop/ui/preview_controller/dialog.py" line="339"/>
         <source>Previewing selected frame</source>
         <translation>Ausgewähltes Bild wird in der Vorschau angezeigt</translation>
     </message>
     <message>
-        <location filename="../src/matteloop/ui/preview_controller/controller.py" line="311"/>
+        <location filename="../src/matteloop/ui/preview_controller/controller.py" line="318"/>
         <location filename="../src/matteloop/ui/preview_controller/dialog.py" line="53"/>
         <location filename="../src/matteloop/ui/preview_controller/dialog.py" line="344"/>
         <source>Preparing model</source>

resources/matteloop_en.ts

@@ -30,7 +30,7 @@
         <translation>Original video frame</translation>
     </message>
     <message>
-        <location filename="../src/matteloop/ui/crop_canvas.py" line="333"/>
+        <location filename="../src/matteloop/ui/crop_canvas.py" line="344"/>
         <source>Crop bounds: x %s, y %s, width %s, height %s source pixels; source %s × %s</source>
         <translation>Crop bounds: x %s, y %s, width %s, height %s source pixels; source %s × %s</translation>
     </message>
@@ -1273,13 +1273,13 @@ Freed %s.</translation>
         <translation>Rendering video</translation>
     </message>
     <message>
-        <location filename="../src/matteloop/ui/preview_controller/controller.py" line="305"/>
+        <location filename="../src/matteloop/ui/preview_controller/controller.py" line="312"/>
         <location filename="../src/matteloop/ui/preview_controller/dialog.py" line="339"/>
         <source>Previewing selected frame</source>
         <translation>Previewing selected frame</translation>
     </message>
     <message>
-        <location filename="../src/matteloop/ui/preview_controller/controller.py" line="311"/>
+        <location filename="../src/matteloop/ui/preview_controller/controller.py" line="318"/>
         <location filename="../src/matteloop/ui/preview_controller/dialog.py" line="53"/>
         <location filename="../src/matteloop/ui/preview_controller/dialog.py" line="344"/>
         <source>Preparing model</source>

src/matteloop/jobs/models/download.py

@@ -176,6 +176,11 @@ def _download_locked(
         if _entry_exists(bound, target_name, spec.id):
             if _verified_file(bound, target_name, artifact, cancelled, spec.id):
                 _assert_bound_named(bound)
+                # Every path that leaves a usable weight on disk reports the
+                # terminal progress, because a caller reads it as "the weight
+                # is now usable". Skipping it here would make selecting an
+                # already-cached model report the model as missing.
+                progress(artifact.size_bytes, artifact.size_bytes)
                 return target
             _safe_unlink(bound, target_name, spec.id)
         _remove_stale_part(bound, part_name, spec.id)
@@ -234,7 +239,7 @@ def _download_locked(
                     except OSError as error:
                         raise _disk_error(spec.id, error) from error
                     digest.update(chunk)
-                    if known_total is not None:
+                    if known_total is not None and completed < known_total:
                         progress(completed, known_total)
                 _raise_if_cancelled(cancelled, spec.id)
                 if completed != artifact.size_bytes:
@@ -267,6 +272,11 @@ def _download_locked(
                 if _verified_file(bound, target_name, artifact, cancelled, spec.id):
                     _safe_unlink(bound, part_name, spec.id)
                     _assert_bound_named(bound)
+                    # Report completion on this path too: a caller that
+                    # treats the terminal progress as "the weight is now
+                    # usable" would otherwise never hear it for a weight
+                    # that was already cached and verified.
+                    progress(artifact.size_bytes, artifact.size_bytes)
                     return target
                 _safe_unlink(bound, target_name, spec.id)
             _before_model_promotion(bound)
@@ -292,6 +302,7 @@ def _download_locked(
                 raise _permission_error(spec.id, error) from error
             except OSError as error:
                 raise _disk_error(spec.id, error) from error
+            progress(artifact.size_bytes, artifact.size_bytes)
             return target
         except BaseException as error:
             try:

src/matteloop/ui/preview_controller/controller.py

@@ -17,6 +17,7 @@
     JobKind,
     JobStageChanged,
     JobState,
+    ModelAvailabilityChanged,
     ModelPrepared,
     PreviewFailed,
     PreviewRequested,
@@ -260,6 +261,12 @@ def _notification(self, notification: object) -> None:
         if self._store.state.job.job_id != job_id:
             return
         if isinstance(notification, ProgressEvent):
+            if (
+                notification.stage is ProgressStage.DOWNLOADING_MODEL
+                and notification.total is not None
+                and notification.completed == notification.total
+            ):
+                self._store.dispatch(ModelAvailabilityChanged(True))
             if self._store.state.job.phase is not JobState.CANCELLING:
                 assert self._dialog is not None
                 self._dialog.set_progress(notification)

tests/jobs/models/test_download.py

@@ -131,14 +131,54 @@ def test_download_streams_to_versioned_part_verifies_and_atomically_promotes(
     assert response.closed is True
 
 
-def test_unknown_content_length_emits_no_byte_progress(tmp_path: Path) -> None:
+def test_download_reports_completion_after_verified_weight_is_promoted(
+    tmp_path: Path,
+) -> None:
+    data = b"verified-model-bytes"
+    target = tmp_path / "2.0.75" / "u2net" / "u2net.onnx"
+    completion_target_states: list[bool] = []
+
+    _download(
+        tmp_path,
+        data,
+        response=FakeResponse(data, headers={"Content-Length": str(len(data))}),
+        progress=lambda done, total: (
+            completion_target_states.append(target.is_file())
+            if done == total
+            else None
+        ),
+    )
+
+    assert completion_target_states == [True]
+
+
+def test_unknown_content_length_reports_post_promotion_completion(
+    tmp_path: Path,
+) -> None:
     events: list[tuple[int, int]] = []
 
     _download(
         tmp_path, b"abcdef", progress=lambda done, total: events.append((done, total))
     )
 
-    assert events == []
+    assert events == [(6, 6)]
+
+
+def test_an_already_cached_weight_still_reports_completion(tmp_path: Path) -> None:
+    """A cached weight takes the early return, and a caller that reads the
+    terminal progress as "usable now" must still hear it there -- otherwise
+    selecting an already-downloaded model reports it as missing.
+    """
+    data = b"abcdef"
+    first: list[tuple[int, int]] = []
+    _download(tmp_path, data, progress=lambda done, total: first.append((done, total)))
+    assert first == [(6, 6)]
+
+    second: list[tuple[int, int]] = []
+
+    _download(tmp_path, data, progress=lambda done, total: second.append((done, total)))
+
+    assert second == [(6, 6)]
 
 
 @pytest.mark.parametrize("cancel_after_call", [1, 3, 6])

tests/ui/test_preview_controller.py

@@ -15,8 +15,10 @@
 from matteloop.core.errors import AppError, ErrorCode
 from matteloop.core.specs import CropSpec
 from matteloop.core.state import (
+    CancelAcknowledged,
     CancelRequested,
     JobStageChanged,
+    ModelAvailabilityChanged,
     ModelPrepared,
     PreviewRequested,
     PreviewState,
@@ -111,6 +113,42 @@ def close(self) -> None:
         return
 
 
+class DownloadedModelFailureRuntime(FakePreviewRuntime):
+    def prepare(
+        self, model_id: str, extras: dict[str, object], context: JobContext
+    ) -> PreparedSegmentation:
+        super().prepare(model_id, extras, context)
+        context.progress(
+            ProgressStage.DOWNLOADING_MODEL,
+            128,
+            total=128,
+            detail="128 / 128 bytes",
+        )
+        raise RuntimeError("segmentation process timed out")
+
+
+class DownloadedModelCancellationRuntime(FakePreviewRuntime):
+    def __init__(self) -> None:
+        super().__init__()
+        self.downloaded = Event()
+
+    def prepare(
+        self, model_id: str, extras: dict[str, object], context: JobContext
+    ) -> PreparedSegmentation:
+        prepared = super().prepare(model_id, extras, context)
+        context.progress(
+            ProgressStage.DOWNLOADING_MODEL,
+            128,
+            total=128,
+            detail="128 / 128 bytes",
+        )
+        self.downloaded.set()
+        while not context.cancellation.requested:
+            Event().wait(0.01)
+        context.checkpoint("model-preparation")
+        return prepared
+
+
 class BlockingPreviewRuntime(FakePreviewRuntime):
     def __init__(self) -> None:
         super().__init__()
@@ -295,6 +333,69 @@ def test_preview_request_uses_the_selected_oriented_crop(tmp_path: Path, qtbot)
     controller.shutdown()
 
 
+def test_completed_model_stays_available_when_preview_setup_fails(
+    tmp_path: Path, qtbot, request
+) -> None:
+    path = tmp_path / "source.mp4"
+    path.write_bytes(b"fixture")
+    runtime = DownloadedModelFailureRuntime()
+    store = RecordingStore()
+    store.dispatch(ModelAvailabilityChanged(False))
+    controller = SourceController(
+        store,
+        source_adapter=FakeSourceAdapter(path),
+        preview_runtime=runtime,
+    )
+    request.addfinalizer(controller.shutdown)
+    window = MainWindow(store, controller, _settings())
+    qtbot.addWidget(window)
+    window.show()
+
+    controller.dispatch(VideoDropped(path))
+    qtbot.waitUntil(lambda: store.state.source.value == "ready", timeout=5000)
+    controller.dispatch(PreviewFrameRequested())
+
+    qtbot.waitUntil(lambda: store.state.preview is PreviewState.ERROR, timeout=5000)
+
+    assert store.state.model_available is True
+    assert window.preview_button.text() == "Preview Frame"
+    assert window.inspector.model_status.text() == "● Ready"
+    assert not window.inspector.model_download_notice.isVisible()
+
+
+def test_completed_model_stays_available_when_preview_is_cancelled(
+    tmp_path: Path, qtbot, request
+) -> None:
+    path = tmp_path / "source.mp4"
+    path.write_bytes(b"fixture")
+    runtime = DownloadedModelCancellationRuntime()
+    store = RecordingStore()
+    store.dispatch(ModelAvailabilityChanged(False))
+    preview_controller = PreviewController(store, runtime=runtime)
+    controller = SourceController(
+        store,
+        source_adapter=FakeSourceAdapter(path),
+        preview_controller=preview_controller,
+    )
+    request.addfinalizer(controller.shutdown)
+    window = MainWindow(store, controller, _settings())
+    qtbot.addWidget(window)
+    window.show()
+
+    controller.dispatch(VideoDropped(path))
+    qtbot.waitUntil(lambda: store.state.source.value == "ready", timeout=5000)
+    controller.dispatch(PreviewFrameRequested())
+    qtbot.waitUntil(runtime.downloaded.is_set, timeout=5000)
+    dialog = preview_controller.dialog
+    assert dialog is not None
+    qtbot.mouseClick(dialog.cancel_button, Qt.MouseButton.LeftButton)
+
+    qtbot.waitUntil(lambda: store.state.job.phase.value == "idle", timeout=5000)
+
+    assert store.state.model_available is True
+    assert any(isinstance(event, CancelAcknowledged) for event in store.events)
+
+
 @pytest.mark.parametrize("use_escape", [False, True])
 def test_cancel_keeps_modal_dialog_open_until_the_safe_checkpoint(
     tmp_path: Path, qtbot, use_escape: bool