feat: v0.3.0 — review welle 2 (M-4, M-5, M-6)

Three resilience and honesty fixes from the v0.2.8 review. Minor
version bump because redeploy_project and system_prune return
different strings.

M-4: trigger_build_stream now converts every non-ReadTimeout
httpx.HTTPError (ConnectError, ConnectTimeout, WriteError,
RemoteProtocolError, ...) into a SynologyError with a clear
message. Previously only ReadTimeout was handled; everything else
propagated as a raw httpx exception. redeploy_project now tracks
whether stop was actually issued and, when build_stream fails after
a successful stop, tells the user the project is in STOPPED state
and recommends start_project / retry rather than the misleading
"use stop + start separately" workaround.

M-5: _wait_for_project_running exits early on BUILD_FAILED / ERROR
(new _TERMINAL_FAILURE_STATUSES frozenset). DSM signals these
statuses within seconds of a failed image pull; the old polling
loop kept waiting up to 5 minutes for RUNNING. redeploy_project
now surfaces the terminal status with a BUILD_FAILED-specific hint
to update_image_tag.

M-6: system_prune preview now enumerates user-created networks
that have no containers attached (excluding the three built-in
networks bridge/host/none, which Docker never prunes). Previously
the preview noted "Unused networks: (not counted)" even though
SYNO.Docker.Utils/prune does delete them — users could lose
networks they had not been warned about.

Tests:
- 2 new dsm_client tests: ConnectError and RemoteProtocolError
  both raise SynologyError, not raw httpx exceptions.
- 2 new project tests: recovery hint after stop+build_stream
  failure (RUNNING case); old workaround retained for the
  STOPPED case where no stop was issued.
- 3 new polling tests: BUILD_FAILED and ERROR each trigger early
  exit; redeploy_project surfaces BUILD_FAILED with update_image_tag
  hint.
- 2 new system_prune preview tests: counts unused networks
  correctly, excludes built-ins; network-fetch failure is non-fatal.

245 tests pass. ruff check + ruff format clean.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/test_modules/test_system.py

@@ -305,3 +305,92 @@ async def test_system_prune_api_error():
 
     result = await tools["system_prune"](confirmed=True)
     assert "Error" in result
+
+
+# ──────────────────────────────────────────────────────────────────────
+#  M-6: system_prune preview now counts unused networks
+# ──────────────────────────────────────────────────────────────────────
+
+
+SAMPLE_NETWORKS_FOR_PRUNE = {
+    "network": [
+        # User-created, no containers attached → will be pruned
+        {"name": "orphan_net", "driver": "bridge", "containers": []},
+        # User-created, in use → must NOT be counted
+        {
+            "name": "myapp_default",
+            "driver": "bridge",
+            "containers": ["web", "db"],
+        },
+        # Built-in networks: Docker never prunes these even if empty
+        {"name": "bridge", "driver": "bridge", "containers": []},
+        {"name": "host", "driver": "host", "containers": []},
+        {"name": "none", "driver": "null", "containers": []},
+        # Another user-created empty network
+        {"name": "legacy_net", "driver": "bridge", "containers": []},
+    ]
+}
+
+
+@pytest.mark.asyncio
+async def test_system_prune_preview_counts_unused_networks() -> None:
+    """M-6: preview must enumerate user-created networks with no containers,
+    skipping the three built-in networks (bridge/host/none)."""
+    from mcp_synology_container.modules.system import register_system
+
+    client = AsyncMock()
+
+    async def mock_request(api, method, **kwargs):
+        if api == "SYNO.Docker.Image":
+            return SAMPLE_IMAGES
+        if api == "SYNO.Docker.Container":
+            return SAMPLE_CONTAINERS
+        if api == "SYNO.Docker.Network":
+            return SAMPLE_NETWORKS_FOR_PRUNE
+        return {}
+
+    client.request.side_effect = mock_request
+    mcp, tools = make_mock_mcp()
+    register_system(mcp, make_config(), client)
+
+    result = await tools["system_prune"]()
+
+    # Two unused user-created networks; the three built-ins must not appear.
+    assert "Unused networks:         2" in result
+    assert "orphan_net" in result
+    assert "legacy_net" in result
+    # Built-in network names must not appear in the prune preview.
+    assert "  - bridge " not in result
+    assert "  - host " not in result
+    assert "  - none " not in result
+    # Network with containers must not be listed.
+    assert "myapp_default" not in result
+    # Old "not counted" placeholder must be gone.
+    assert "not counted" not in result
+
+
+@pytest.mark.asyncio
+async def test_system_prune_preview_network_fetch_failure_is_nonfatal() -> None:
+    """If the network list fetch fails, the preview still works (0 networks)."""
+    from mcp_synology_container.dsm_client import SynologyError
+    from mcp_synology_container.modules.system import register_system
+
+    client = AsyncMock()
+
+    async def mock_request(api, method, **kwargs):
+        if api == "SYNO.Docker.Image":
+            return SAMPLE_IMAGES
+        if api == "SYNO.Docker.Container":
+            return SAMPLE_CONTAINERS
+        if api == "SYNO.Docker.Network":
+            raise SynologyError("network list failed", code=100)
+        return {}
+
+    client.request.side_effect = mock_request
+    mcp, tools = make_mock_mcp()
+    register_system(mcp, make_config(), client)
+
+    result = await tools["system_prune"]()
+    # Preview still renders; networks count falls back to 0.
+    assert "preview" in result.lower()
+    assert "Unused networks:         0" in result