feat: clean up stale targets removed from config on next build

When a target is present in the state file but no longer in the config,
its output file is deleted (or archived if archive_folder is set) and
its state entry is removed. This runs at the start of every build.

tests/test_builder.py

@@ -709,6 +709,135 @@ class TestContentTarget:
         assert result.failed == {}
 
 
+class TestStaleTargetCleanup:
+    """Tests for cleanup of targets removed from config."""
+
+    async def test_stale_target_file_deleted(
+        self, project_dir: Path, write_config: WriteConfig
+    ) -> None:
+        config1 = write_config(
+            {
+                "targets": {
+                    "a.txt": {"prompt": "first"},
+                    "b.txt": {"prompt": "second"},
+                }
+            }
+        )
+        with patch("hokusai.builder._create_providers", return_value=_fake_providers()):
+            r1 = await run_build(config1, project_dir, _PROJECT)
+            assert set(r1.built) == {"a.txt", "b.txt"}
+
+            # Remove b.txt from config
+            config2 = write_config({"targets": {"a.txt": {"prompt": "first"}}})
+            r2 = await run_build(config2, project_dir, _PROJECT)
+
+        assert not (project_dir / "b.txt").exists()
+        assert "a.txt" in r2.skipped
+
+    async def test_stale_target_archived(
+        self, project_dir: Path, write_config: WriteConfig
+    ) -> None:
+        config1 = write_config(
+            {
+                "archive_folder": "archive",
+                "targets": {
+                    "a.txt": {"prompt": "first"},
+                    "b.txt": {"prompt": "second"},
+                },
+            }
+        )
+        with patch("hokusai.builder._create_providers", return_value=_fake_providers()):
+            r1 = await run_build(config1, project_dir, _PROJECT)
+            assert set(r1.built) == {"a.txt", "b.txt"}
+
+            config2 = write_config(
+                {
+                    "archive_folder": "archive",
+                    "targets": {"a.txt": {"prompt": "first"}},
+                }
+            )
+            _ = await run_build(config2, project_dir, _PROJECT)
+
+        assert not (project_dir / "b.txt").exists()
+        assert (project_dir / "archive" / "b.01.txt").exists()
+
+    async def test_stale_state_entry_removed(
+        self, project_dir: Path, write_config: WriteConfig
+    ) -> None:
+        config1 = write_config(
+            {
+                "targets": {
+                    "a.txt": {"prompt": "first"},
+                    "b.txt": {"prompt": "second"},
+                }
+            }
+        )
+        with patch("hokusai.builder._create_providers", return_value=_fake_providers()):
+            _ = await run_build(config1, project_dir, _PROJECT)
+
+            state = load_state(project_dir, _PROJECT)
+            assert "b.txt" in state.targets
+
+            config2 = write_config({"targets": {"a.txt": {"prompt": "first"}}})
+            _ = await run_build(config2, project_dir, _PROJECT)
+
+        state = load_state(project_dir, _PROJECT)
+        assert "b.txt" not in state.targets
+        assert "a.txt" in state.targets
+
+    async def test_stale_target_file_already_gone(
+        self, project_dir: Path, write_config: WriteConfig
+    ) -> None:
+        config1 = write_config(
+            {
+                "targets": {
+                    "a.txt": {"prompt": "first"},
+                    "b.txt": {"prompt": "second"},
+                }
+            }
+        )
+        with patch("hokusai.builder._create_providers", return_value=_fake_providers()):
+            _ = await run_build(config1, project_dir, _PROJECT)
+            (project_dir / "b.txt").unlink()
+
+            config2 = write_config({"targets": {"a.txt": {"prompt": "first"}}})
+            _ = await run_build(config2, project_dir, _PROJECT)
+
+        # State entry should still be cleaned even if file is gone
+        state = load_state(project_dir, _PROJECT)
+        assert "b.txt" not in state.targets
+
+    async def test_stale_cleanup_emits_progress(
+        self, project_dir: Path, write_config: WriteConfig
+    ) -> None:
+        from hokusai.builder import BuildEvent
+
+        config1 = write_config(
+            {
+                "targets": {
+                    "a.txt": {"prompt": "first"},
+                    "b.txt": {"prompt": "second"},
+                }
+            }
+        )
+        events: list[tuple[BuildEvent, str, str]] = []
+
+        def recorder(event: BuildEvent, name: str, detail: str) -> None:
+            events.append((event, name, detail))
+
+        with patch("hokusai.builder._create_providers", return_value=_fake_providers()):
+            _ = await run_build(config1, project_dir, _PROJECT, on_progress=recorder)
+            events.clear()
+
+            config2 = write_config({"targets": {"a.txt": {"prompt": "first"}}})
+            _ = await run_build(config2, project_dir, _PROJECT, on_progress=recorder)
+
+        removed_events = [
+            (e, n) for e, n, _ in events if e is BuildEvent.TARGET_REMOVED
+        ]
+        assert ("b.txt",) in [(n,) for _, n in removed_events]
+
+
 class TestLoopExpansion:
     """End-to-end tests for loop-expanded targets in builds."""