fix(watcher): don't re-ingest a note that cannot be retired; pin archive-failure keeps original

When both Remove and the marker write fail (read-only raw/), remember the
path in memory so later polls skip it instead of writing another archive
copy every tick. Adds a test that a failed archive copy leaves the original
in raw/, mutation-checked against removing the early return.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

ingestion/internal/watcher/watcher_test.go

@@ -387,3 +387,60 @@ func TestProcessDir_DoesNotHangUnderAFIFOSwapRace(t *testing.T) {
 		t.Fatalf("the watcher hung on a swapped-in FIFO after %d iterations", iters.Load())
 	}
 }
+
+// A note whose removal AND marker write both fail (read-only raw/) must not be
+// re-ingested on every poll: each pass would write another archive copy.
+func TestProcessDir_DoesNotReingestANoteItCannotRetire(t *testing.T) {
+	brainDir := setupBrainDir(t)
+	rawDir := filepath.Join(brainDir, "raw")
+	require.NoError(t, os.WriteFile(filepath.Join(rawDir, "stuck.md"), []byte("Content."), 0o644))
+	// processed/ must exist and stay writable; only raw/ itself is locked.
+	require.NoError(t, os.MkdirAll(filepath.Join(rawDir, "processed"), 0o755))
+	require.NoError(t, os.Chmod(rawDir, 0o555))
+	t.Cleanup(func() { _ = os.Chmod(rawDir, 0o755) })
+
+	var calls atomic.Int32
+	cfg := Config{
+		BrainDir: brainDir,
+		Pipeline: pipeline.Config{
+			Complete: func(ctx context.Context, s, u string) (string, error) {
+				calls.Add(1)
+				return successComplete(pipeline.RawPage{Title: "Stuck", Type: "source", Subtype: "article", Content: "x\n"})(ctx, s, u)
+			},
+			Schema: "# Schema",
+		},
+		stuck: &sync.Map{},
+	}
+	for i := 0; i < 3; i++ {
+		processDir(context.Background(), cfg, "2026-10-19")
+	}
+	assert.Equal(t, int32(1), calls.Load(), "a note that cannot be retired is ingested once, not once per poll")
+}
+
+// If the archive copy cannot be written, the original is the only copy left:
+// it must stay in raw/.
+func TestProcessDir_KeepsTheOriginalWhenTheArchiveCopyFails(t *testing.T) {
+	brainDir := setupBrainDir(t)
+	rawDir := filepath.Join(brainDir, "raw")
+	note := filepath.Join(rawDir, "keep-me.md")
+	require.NoError(t, os.WriteFile(note, []byte("Content."), 0o644))
+	// The dated archive dir exists but is read-only: MkdirAll succeeds, the
+	// copy itself (os.Create) fails.
+	dated := filepath.Join(rawDir, "processed", "2026-10-19")
+	require.NoError(t, os.MkdirAll(dated, 0o755))
+	require.NoError(t, os.Chmod(dated, 0o555))
+	t.Cleanup(func() { _ = os.Chmod(dated, 0o755) })
+
+	cfg := Config{
+		BrainDir: brainDir,
+		Pipeline: pipeline.Config{
+			Complete: successComplete(pipeline.RawPage{Title: "Keep Me", Type: "source", Subtype: "article", Content: "x\n"}),
+			Schema:   "# Schema",
+		},
+	}
+	errs := processDir(context.Background(), cfg, "2026-10-19")
+
+	assert.NotEmpty(t, errs, "the failed archive is reported")
+	_, err := os.Stat(note)
+	assert.NoError(t, err, "original stays in raw/ when it could not be archived")
+}