merge: land #195 (watcher/pipeline writes through the brain root, #158 part B) on top of inbox zero and the wing resolver

Reconciled with v0.25.0 semantics:
- markers are only the fallback when the original cannot be removed, and are
  now written through the brain root; the refused set (size+mtime keyed) replaces
  the path-only 'stuck' set
- #195's tests updated for inbox zero (archive written, original retired, no
  marker), and the planted-marker-link test keeps its point: nothing is ever
  written through the link, and the note is processed once
- the 'cannot retire' test now counts archive copies; it counted LLM calls,
  which pipeline.Run's source-hash check hides (mutation: removing the
  remember step left it green)

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

ingestion/cmd/server/main_test.go

@@ -77,6 +77,30 @@ func TestAlertingWarnings(t *testing.T) {
 	}
 }
 
+// hyperguild#158: the claude-session archive was written with os.MkdirAll +
+// os.WriteFile by path, so a symlinked archive directory redirected it.
+func TestClaudeSinkDoesNotWriteThroughASymlinkedArchiveDir(t *testing.T) {
+	for name, mk := range map[string]func(t *testing.T, dir string) (link, target string){
+		"outside": func(t *testing.T, _ string) (string, string) { o := t.TempDir(); return o, o },
+		"in-brain": func(t *testing.T, dir string) (string, string) {
+			require.NoError(t, os.MkdirAll(filepath.Join(dir, "raw"), 0o755))
+			return filepath.Join("..", "raw"), filepath.Join(dir, "raw")
+		},
+	} {
+		t.Run(name, func(t *testing.T) {
+			dir := t.TempDir()
+			link, target := mk(t, dir)
+			require.NoError(t, os.Symlink(link, filepath.Join(dir, "archive")))
+			sink := &claudeSink{brainDir: dir, logger: slog.New(slog.NewTextHandler(os.Stderr, nil))}
+			err := sink.Ingest(context.Background(), claudewatcher.Batch{Host: "koala", SessionID: "abc",
+				Turns: []claudewatcher.Turn{{Type: "assistant", Content: "x"}}})
+			assert.Error(t, err)
+			ents, _ := os.ReadDir(target)
+			assert.Empty(t, ents, "the archive was written at the link's target")
+		})
+	}
+}
+
 func TestEnvFloat(t *testing.T) {
 	tests := []struct {
 		name string