test: pin CreateRegular directly and promote/reject with in-brain targets (#188)

Review round 2 on PR #189: CreateRegular (promote's and reject's only
write path) had no test; replacing mkdirReal with root.MkdirAll, dropping
cleanRel or calling PutRegular all stayed green, and the promote/reject
test planted only outside targets, which os.Root refuses on its own.

- TestCreateRegularCreatesOnlyNewFilesThroughRealDirectories: in-brain
  symlinked parent, unclean path, existing file and dangling link
  (fs.ErrExist, nothing changed), positive control with missing parents.
- TestPromoteAndRejectRefuseAnInBrainSymlinkedDestinationDirectory.

All three flips are red now.

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

ingestion/cmd/server/main.go

@@ -17,7 +17,6 @@ import (
 
 	"github.com/mathiasbq/hyperguild/ingestion/internal/api"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/audit"
-	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/capture"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/capturehttp"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/classification"
@@ -90,15 +89,11 @@ func (s *claudeSink) Ingest(ctx context.Context, b claudewatcher.Batch) error {
 		sb.WriteString("\n\n")
 	}
 	slug := "session-" + b.Host + "-" + b.SessionID
-	dest := "archive/claude-sessions/" + b.Host + "/" + slug + ".md"
-	// Written through the brain root, never through a symlinked directory
-	// or file (hyperguild#158).
-	bfs, err := brainfs.Open(s.brainDir)
-	if err != nil {
-		return fmt.Errorf("open brain: %w", err)
+	dest := filepath.Join(s.brainDir, "archive", "claude-sessions", b.Host, slug+".md")
+	if err := os.MkdirAll(filepath.Dir(dest), 0o755); err != nil {
+		return fmt.Errorf("create claude-sessions archive dir: %w", err)
 	}
-	defer func() { _ = bfs.Close() }()
-	if err := bfs.PutRegular(dest, []byte(sb.String())); err != nil {
+	if err := os.WriteFile(dest, []byte(sb.String()), 0o644); err != nil {
 		return fmt.Errorf("write claude session archive: %w", err)
 	}
 	s.logger.Debug("claude session archived (non-indexed)", "path", dest)

ingestion/cmd/server/symlink_check_test.go

@@ -4,7 +4,6 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
-	"syscall"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -64,13 +63,3 @@ func TestStartupSymlinkCheckRefusesAnUnlistableBrainRoot(t *testing.T) {
 	t.Cleanup(func() { _ = os.Chmod(brain, 0o755) })
 	assert.Error(t, startupSymlinkCheck(brain))
 }
-
-// hyperguild#179: a FIFO in the brain is refused at startup with a clear
-// message, instead of hanging or exiting later in a reader.
-func TestStartupSymlinkCheckRefusesABrainWithAFIFO(t *testing.T) {
-	brain := t.TempDir()
-	require.NoError(t, syscall.Mkfifo(filepath.Join(brain, "classification.yaml"), 0o644))
-	err := startupSymlinkCheck(brain)
-	require.Error(t, err)
-	assert.Contains(t, err.Error(), "classification.yaml")
-}

ingestion/internal/api/write_keeps_learning_test.go

@@ -1,34 +0,0 @@
-package api_test
-
-import (
-	"os"
-	"path/filepath"
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-
-	"github.com/mathiasbq/hyperguild/ingestion/internal/api"
-)
-
-// hyperguild#178: an unreadable directory under wiki/ made the link check
-// fail and brain_write refuse the note, losing the learning. The note is now
-// written with its links as given.
-func TestWriteNoteKeepsTheLearningWhenTheLinkCheckCannotIndex(t *testing.T) {
-	if os.Geteuid() == 0 {
-		t.Skip("root ignores directory permissions")
-	}
-	brain := t.TempDir()
-	require.NoError(t, os.MkdirAll(filepath.Join(brain, "wiki", "w", "facts"), 0o755))
-	require.NoError(t, os.WriteFile(filepath.Join(brain, "wiki", "w", "facts", "real.md"), []byte("x"), 0o644))
-	locked := filepath.Join(brain, "wiki", "other", "locked")
-	require.NoError(t, os.MkdirAll(locked, 0o755))
-	require.NoError(t, os.Chmod(locked, 0o000))
-	t.Cleanup(func() { _ = os.Chmod(locked, 0o755) })
-
-	rel, err := api.WriteNote(brain, api.WriteNoteOptions{Wing: "w", Hall: "facts", Filename: "n", Content: "learning [[real]] and [[gone]]"})
-	require.NoError(t, err)
-	got, err := os.ReadFile(filepath.Join(brain, filepath.FromSlash(rel)))
-	require.NoError(t, err)
-	assert.Contains(t, string(got), "[[gone]]", "links kept as given when the index is partial")
-}

ingestion/internal/brain/linkcheck.go

@@ -47,12 +47,7 @@ var (
 func StripUnresolvedLinks(brainDir, content string) (string, []string, error) {
 	index, err := entryIndex(brainDir)
 	if err != nil {
-		// A partial index cannot tell an invented link from one into the
-		// part it could not read, so unwrap nothing, and do not refuse the
-		// write either: this runs before every brain_write, and a refused
-		// write is a lost learning (hyperguild#178).
-		slog.Warn("link check skipped: cannot index the brain", "err", err)
-		return content, nil, nil
+		return "", nil, err
 	}
 	if len(index) == 0 {
 		return content, nil, nil

ingestion/internal/brain/linkcheck_fallback_test.go

@@ -1,41 +0,0 @@
-package brain_test
-
-import (
-	"os"
-	"path/filepath"
-	"testing"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-
-	"github.com/mathiasbq/hyperguild/ingestion/internal/brain"
-)
-
-// hyperguild#178: StripUnresolvedLinks runs before every brain_write and
-// brain_update. An unreadable directory under knowledge/ or wiki/ made it
-// error, the write was refused and the learning lost. When the link index
-// cannot be built, the content is now returned unchanged (no link is
-// unwrapped, none is invented) and no error stops the write.
-func TestStripUnresolvedLinksKeepsContentWhenTheIndexCannotBeBuilt(t *testing.T) {
-	if os.Geteuid() == 0 {
-		t.Skip("root ignores directory permissions")
-	}
-	b := t.TempDir()
-	require.NoError(t, os.MkdirAll(filepath.Join(b, "wiki", "w", "facts"), 0o755))
-	require.NoError(t, os.WriteFile(filepath.Join(b, "wiki", "w", "facts", "real.md"), []byte("x"), 0o644))
-	locked := filepath.Join(b, "wiki", "other", "locked")
-	require.NoError(t, os.MkdirAll(locked, 0o755))
-	require.NoError(t, os.Chmod(locked, 0o000))
-	t.Cleanup(func() { _ = os.Chmod(locked, 0o755) })
-
-	in := "learning [[real]] and [[gone]]"
-	out, unlinked, err := brain.StripUnresolvedLinks(b, in)
-	require.NoError(t, err)
-	assert.Equal(t, in, out, "content unchanged: no link unwrapped on a partial index")
-	assert.Empty(t, unlinked)
-
-	require.NoError(t, os.Chmod(locked, 0o755))
-	out, _, err = brain.StripUnresolvedLinks(b, in)
-	require.NoError(t, err)
-	assert.NotContains(t, out, "[[gone]]", "positive control: with a readable tree the strip runs")
-}

ingestion/internal/brainfs/brainfs.go

@@ -243,27 +243,6 @@ func (b *Brain) RealParent(rel string) error {
 	return b.realDir(path.Dir(rel))
 }
 
-// PutFile opens the brain dir as a root and calls PutRegular, for one-off
-// writers that hold no Brain.
-func PutFile(brainDir, rel string, data []byte) error {
-	b, err := Open(brainDir)
-	if err != nil {
-		return err
-	}
-	defer func() { _ = b.Close() }()
-	return b.PutRegular(rel, data)
-}
-
-// AppendFile opens the brain dir as a root and calls AppendRegular.
-func AppendFile(brainDir, rel string, data []byte) error {
-	b, err := Open(brainDir)
-	if err != nil {
-		return err
-	}
-	defer func() { _ = b.Close() }()
-	return b.AppendRegular(rel, data)
-}
-
 // mkdirReal makes sure every component of rel exists as a real directory,
 // creating missing ones through the root; an existing component that is
 // not a real directory is ErrNotRegular.

ingestion/internal/pipeline/backfill.go

@@ -7,6 +7,8 @@ import (
 	"fmt"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs"
 	"io/fs"
+	"os"
+	"path/filepath"
 	"strings"
 
 	"github.com/mathiasbq/hyperguild/ingestion/internal/wiki"
@@ -88,7 +90,8 @@ func BackfillRefs(ctx context.Context, brainDir string) (int, error) {
 	}
 
 	for relPath, page := range pending {
-		if err := bfs.PutRegular(relPath, []byte(page.Content)); err != nil {
+		dest := filepath.Join(brainDir, filepath.FromSlash(relPath))
+		if err := os.WriteFile(dest, []byte(page.Content), 0o644); err != nil {
 			return 0, fmt.Errorf("write %s: %w", relPath, err)
 		}
 	}

ingestion/internal/pipeline/pipeline.go

@@ -9,6 +9,8 @@ import (
 	"fmt"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs"
 	"io/fs"
+	"os"
+	"path/filepath"
 	"strings"
 	"time"
 
@@ -126,6 +128,10 @@ func buildAndWrite(ctx context.Context, rawPages []RawPage, sourceSlug, date, br
 	var written []string
 	for _, page := range merged {
 		if !dryRun {
+			dest := filepath.Join(brainDir, filepath.FromSlash(page.Path))
+			if err := os.MkdirAll(filepath.Dir(dest), 0o755); err != nil {
+				return Result{}, fmt.Errorf("mkdir for %s: %w", page.Path, err)
+			}
 			content, conflicts, err := reviseOrCreate(brainDir, page)
 			if err != nil {
 				return Result{}, err
@@ -144,9 +150,7 @@ func buildAndWrite(ctx context.Context, rawPages []RawPage, sourceSlug, date, br
 			if err != nil {
 				return Result{}, fmt.Errorf("stamp %s: %w", page.Path, err)
 			}
-			// Written through the brain root, never through a symlinked
-			// directory or page (hyperguild#158).
-			if err := writeBrainFile(brainDir, page.Path, []byte(stamped)); err != nil {
+			if err := os.WriteFile(dest, []byte(stamped), 0o644); err != nil {
 				return Result{}, fmt.Errorf("write %s: %w", page.Path, err)
 			}
 		}
@@ -197,17 +201,6 @@ func readSourcePage(brainDir, sourceSlug string) string {
 	return string(raw)
 }
 
-// writeBrainFile creates or replaces one brain-relative file through the
-// brain root (hyperguild#158).
-func writeBrainFile(brainDir, rel string, data []byte) error {
-	bfs, err := brainfs.Open(brainDir)
-	if err != nil {
-		return err
-	}
-	defer func() { _ = bfs.Close() }()
-	return bfs.PutRegular(rel, data)
-}
-
 // readBrainFile reads one brain-relative file through the brain root,
 // regular files only (hyperguild#157).
 func readBrainFile(brainDir, rel string) ([]byte, error) {

ingestion/internal/pipeline/root_test.go

@@ -165,28 +165,3 @@ func TestBackfillRefsDoesNotCopyAPageSwappedInBehindASymlink(t *testing.T) {
 	require.Contains(t, read(), "[[s|S]]", "positive control: the regular page gets the source ref")
 	brainfstest.AssertNoLeakFrom(t, page, inside, target, 3*time.Second, read)
 }
-
-// hyperguild#158: BackfillRefs read a regular concept page, a symlink could
-// be swapped in, and os.WriteFile then followed it and overwrote the link's
-// target. The target is not restored between rounds here, so any
-// write-through shows.
-func TestBackfillRefsNeverWritesThroughAPageSwappedForASymlink(t *testing.T) {
-	brain := t.TempDir()
-	mkdirs(t, brain, "wiki/sources", "wiki/concepts", "raw")
-	require.NoError(t, os.WriteFile(filepath.Join(brain, "wiki", "sources", "s.md"), []byte("---\ntitle: S\n---\n[[c|C]]\n"), 0o644))
-	page := filepath.Join(brain, "wiki", "concepts", "c.md")
-	target := filepath.Join(brain, "raw", "secret.md")
-	require.NoError(t, os.WriteFile(target, []byte("untouched"), 0o644))
-	inside := "---\ntitle: C\n---\nbody\n"
-	require.NoError(t, os.WriteFile(page, []byte(inside), 0o644))
-	brainfstest.StartSwap(t, page, inside, target, false)
-	ok := 0
-	for deadline := time.Now().Add(2 * time.Second); time.Now().Before(deadline); {
-		if _, err := BackfillRefs(context.Background(), brain); err == nil {
-			ok++
-		}
-	}
-	got, _ := os.ReadFile(target)
-	assert.Equal(t, "untouched", string(got), "BackfillRefs wrote through a swapped-in symlink")
-	assert.Positive(t, ok, "positive control: some backfills ran")
-}

ingestion/internal/symlinkguard/special_test.go

@@ -1,104 +0,0 @@
-package symlinkguard
-
-import (
-	"context"
-	"net"
-	"os"
-	"path/filepath"
-	"syscall"
-	"testing"
-	"time"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-// hyperguild#179: the tripwire looked only for symlinks, so a FIFO (or
-// socket) in the brain passed it. A FIFO at classification.yaml then made
-// startup exit; at a note path it could hang readers that skip the handle
-// check.
-func TestScanReportsFIFOsAndSocketsAsSpecialFiles(t *testing.T) {
-	brain := t.TempDir()
-	require.NoError(t, os.MkdirAll(filepath.Join(brain, "wiki", "w"), 0o755))
-	require.NoError(t, syscall.Mkfifo(filepath.Join(brain, "classification.yaml"), 0o644))
-	require.NoError(t, syscall.Mkfifo(filepath.Join(brain, "wiki", "w", "f.md"), 0o644))
-	l, err := net.Listen("unix", filepath.Join(brain, "s.sock"))
-	require.NoError(t, err)
-	defer func() { _ = l.Close() }()
-	require.NoError(t, os.WriteFile(filepath.Join(brain, "wiki", "w", "n.md"), []byte("n"), 0o644))
-
-	r, err := Scan(brain)
-	require.NoError(t, err)
-	assert.Equal(t, []string{"classification.yaml", "s.sock", "wiki/w/f.md"}, r.Special)
-	assert.False(t, r.Clean())
-	assert.Contains(t, r.String(), "special file")
-}
-
-// Watch removes a FIFO as it removes symlinks, and leaves a regular file
-// (which Scan never reports) alone.
-func TestWatchRemovesAFIFOAndLeavesAnUnreportedRegularFile(t *testing.T) {
-	brain := t.TempDir()
-	fifo := filepath.Join(brain, "f.md")
-	require.NoError(t, syscall.Mkfifo(fifo, 0o644))
-	regular := filepath.Join(brain, "n.md")
-	require.NoError(t, os.WriteFile(regular, []byte("n"), 0o644))
-	n := &recNotifier{}
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-	go Watch(ctx, brain, 10*time.Millisecond, n)
-	require.Eventually(t, func() bool {
-		_, err := os.Lstat(fifo)
-		return os.IsNotExist(err)
-	}, 2*time.Second, 10*time.Millisecond, "the FIFO is removed")
-	require.Eventually(t, func() bool { return n.count() >= 1 }, 2*time.Second, 10*time.Millisecond)
-	b, err := os.ReadFile(regular)
-	require.NoError(t, err)
-	assert.Equal(t, "n", string(b))
-	n.mu.Lock()
-	defer n.mu.Unlock()
-	assert.Contains(t, n.msgs[0], "f.md")
-}
-
-// removeSpecial re-checks the type: a path that is a regular file or a
-// directory at the re-check is not removed. (A swap between the re-check and
-// the unlink can still remove one; Linux has no conditional unlink. The same
-// window exists in removeSymlinks.)
-func TestRemoveSpecialRefusesRegularFilesAndDirectories(t *testing.T) {
-	brain := t.TempDir()
-	require.NoError(t, os.WriteFile(filepath.Join(brain, "n.md"), []byte("n"), 0o644))
-	require.NoError(t, os.MkdirAll(filepath.Join(brain, "d"), 0o755))
-	require.NoError(t, syscall.Mkfifo(filepath.Join(brain, "f.md"), 0o644))
-	removed, failed := removeSpecial(brain, []string{"n.md", "d", "f.md"})
-	assert.Equal(t, []string{"f.md"}, removed)
-	assert.Equal(t, []string{"n.md", "d"}, failed)
-	_, err := os.Stat(filepath.Join(brain, "n.md"))
-	assert.NoError(t, err)
-}
-
-// A special file Watch cannot remove (its directory is read-only) stays
-// reported: the persistent-finding alert names it.
-func TestWatchReportsASpecialFileItCannotRemove(t *testing.T) {
-	if os.Geteuid() == 0 {
-		t.Skip("root ignores directory permissions")
-	}
-	brain := t.TempDir()
-	ro := filepath.Join(brain, "ro")
-	require.NoError(t, os.MkdirAll(ro, 0o755))
-	require.NoError(t, syscall.Mkfifo(filepath.Join(ro, "f.md"), 0o644))
-	require.NoError(t, os.Chmod(ro, 0o555))
-	t.Cleanup(func() { _ = os.Chmod(ro, 0o755) })
-	n := &recNotifier{}
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-	go Watch(ctx, brain, 10*time.Millisecond, n)
-	require.Eventually(t, func() bool { return n.count() >= 1 }, 2*time.Second, 10*time.Millisecond)
-	_, err := os.Lstat(filepath.Join(ro, "f.md"))
-	require.NoError(t, err, "the FIFO could not be removed")
-	n.mu.Lock()
-	defer n.mu.Unlock()
-	assert.Contains(t, n.msgs[0], "ro/f.md")
-	assert.Contains(t, n.msgs[0], "special file")
-	for _, m := range n.msgs {
-		assert.NotContains(t, m, "removed", "a file it could not remove was reported as removed")
-	}
-}

ingestion/internal/symlinkguard/symlinkguard.go

@@ -46,16 +46,10 @@ type Notifier interface {
 type Result struct {
 	Symlinks   []string
 	Unreadable []string
-	// Special holds FIFOs, sockets and devices (hyperguild#179): a reader
-	// that opens one by path can hang, and a FIFO at classification.yaml
-	// stops startup.
-	Special []string
 }
 
 // Clean reports whether the scan found nothing to act on.
-func (r Result) Clean() bool {
-	return len(r.Symlinks) == 0 && len(r.Unreadable) == 0 && len(r.Special) == 0
-}
+func (r Result) Clean() bool { return len(r.Symlinks) == 0 && len(r.Unreadable) == 0 }
 
 // String describes the findings for a log line or alert. Paths are quoted, so
 // a name containing a newline cannot blur two findings together.
@@ -65,9 +59,6 @@ func (r Result) String() string {
 	if len(r.Symlinks) > 0 {
 		parts = append(parts, fmt.Sprintf("%d symlink(s): %s", len(r.Symlinks), q(r.Symlinks)))
 	}
-	if len(r.Special) > 0 {
-		parts = append(parts, fmt.Sprintf("%d special file(s) (FIFO, socket or device; delete them): %s", len(r.Special), q(r.Special)))
-	}
 	if len(r.Unreadable) > 0 {
 		parts = append(parts, fmt.Sprintf("%d unreadable dir(s): %s", len(r.Unreadable), q(r.Unreadable)))
 	}
@@ -122,16 +113,12 @@ func Scan(brainDir string) (Result, error) {
 		if d.IsDir() && p == rootGit {
 			return filepath.SkipDir
 		}
-		switch {
-		case d.Type()&os.ModeSymlink != 0:
+		if d.Type()&os.ModeSymlink != 0 {
 			r.Symlinks = append(r.Symlinks, rel)
-		case !d.IsDir() && !d.Type().IsRegular():
-			r.Special = append(r.Special, rel)
 		}
 		return nil
 	})
 	sort.Strings(r.Symlinks)
-	sort.Strings(r.Special)
 	sort.Strings(r.Unreadable)
 	if walkErr != nil {
 		// Only the root's own error reaches here (deeper errors are recorded
@@ -195,20 +182,14 @@ func Watch(ctx context.Context, brainDir string, interval time.Duration, n Notif
 				q.push(fmt.Sprintf("brain symlink tripwire (hyperguild#157): removed %d symlink(s) from the brain dir: %s",
 					len(removed), Result{}.quoted(removed)))
 			}
-			sRemoved, sFailed := removeSpecial(brainDir, r.Special)
-			if len(sRemoved) > 0 {
-				slog.Error("brain symlink tripwire removed special files", "count", len(sRemoved))
-				q.push(fmt.Sprintf("brain symlink tripwire (hyperguild#179): removed %d special file(s) (FIFO, socket or device) from the brain dir: %s",
-					len(sRemoved), Result{}.quoted(sRemoved)))
-			}
-			key = Result{Symlinks: failed, Unreadable: r.Unreadable, Special: sFailed}.String()
+			key = Result{Symlinks: failed, Unreadable: r.Unreadable}.String()
 		}
 		if key != reported {
 			reported = key
 			if key != "" {
 				slog.Error("brain symlink tripwire", "finding", key)
-				q.push("brain symlink tripwire (hyperguild#157, #179): " + key +
-					". Symlinks can lead readers out of the brain and special files can hang them; remove them.")
+				q.push("brain symlink tripwire (hyperguild#157): " + key +
+					". Readers may follow symlinks out of the brain; fix them.")
 			}
 		}
 	}
@@ -341,40 +322,6 @@ func permanent(err error) bool {
 	return errors.As(err, &p) && p.Permanent()
 }
 
-// removeSpecial unlinks each brain-relative FIFO, socket or device through
-// an os.Root on the brain dir, after re-checking that it is still one: a
-// path that is a regular file, a directory or a symlink at the re-check is
-// left alone and reported as failed. The re-check narrows, but cannot close,
-// the window before the unlink (Linux has no conditional unlink); the same
-// window exists in removeSymlinks, and only a local writer can use it.
-func removeSpecial(brainDir string, rels []string) (removed, failed []string) {
-	if len(rels) == 0 {
-		return nil, nil
-	}
-	resolved, err := filepath.EvalSymlinks(brainDir)
-	if err != nil {
-		return nil, rels
-	}
-	root, err := os.OpenRoot(resolved)
-	if err != nil {
-		return nil, rels
-	}
-	defer func() { _ = root.Close() }()
-	for _, rel := range rels {
-		fi, err := root.Lstat(rel)
-		if err != nil || fi.IsDir() || fi.Mode().IsRegular() || fi.Mode()&os.ModeSymlink != 0 {
-			failed = append(failed, rel)
-			continue
-		}
-		if err := root.Remove(rel); err != nil {
-			failed = append(failed, rel)
-			continue
-		}
-		removed = append(removed, rel)
-	}
-	return removed, failed
-}
-
 // removeSymlinks unlinks each brain-relative symlink through an os.Root on
 // the brain dir, after re-checking it is still a symlink. Removing a symlink
 // never touches its target. It returns what was removed and what was not.

ingestion/internal/watcher/watcher.go

@@ -12,7 +12,6 @@ import (
 	"time"
 	"unicode"
 
-	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/extract"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/pipeline"
 )
@@ -146,12 +145,16 @@ func processFile(ctx context.Context, cfg Config, root *os.Root, rawDir, path, d
 
 	_, runErr := pipeline.Run(ctx, cfg.Pipeline, cfg.BrainDir, content, source, false)
 	if runErr != nil {
-		// Copy to failed/ and leave a .failed marker so we don't retry. Both
-		// written through the brain root (hyperguild#158).
-		if cpErr := copyFromRoot(root, rel, cfg.BrainDir, "raw/failed/"+filename); cpErr != nil {
+		// Copy to failed/ and leave a .failed marker so we don't retry.
+		failedDir := filepath.Join(cfg.BrainDir, "raw", "failed")
+		if mkErr := os.MkdirAll(failedDir, 0o755); mkErr != nil {
+			return fmt.Errorf("mkdir failed dir: %w", mkErr)
+		}
+		dest := filepath.Join(failedDir, filename)
+		if cpErr := copyFromRoot(root, rel, dest); cpErr != nil {
 			return fmt.Errorf("copy to failed: %w", cpErr)
 		}
-		if mkErr := putBrainFile(cfg.BrainDir, "raw/"+filepath.ToSlash(rel)+".failed", []byte(runErr.Error())); mkErr != nil {
+		if mkErr := os.WriteFile(path+".failed", []byte(runErr.Error()), 0o644); mkErr != nil {
 			slog.Error("watcher: failed to write .failed marker", "error", mkErr)
 		}
 
@@ -165,18 +168,21 @@ func processFile(ctx context.Context, cfg Config, root *os.Root, rawDir, path, d
 	}
 
 	// Copy to processed/YYYY-MM-DD/ and leave a .processed marker so we don't re-ingest.
-	// Written through the brain root (hyperguild#158).
-	dest := "raw/processed/" + date + "/" + filename
-	if _, err := os.Lstat(filepath.Join(cfg.BrainDir, filepath.FromSlash(dest))); err == nil {
+	processedDir := filepath.Join(cfg.BrainDir, "raw", "processed", date)
+	if err := os.MkdirAll(processedDir, 0o755); err != nil {
+		return fmt.Errorf("mkdir processed dir: %w", err)
+	}
+	dest := filepath.Join(processedDir, filename)
+	if _, err := os.Stat(dest); err == nil {
 		// Archive copy already exists; append timestamp to avoid overwriting.
 		ext := filepath.Ext(filename)
 		base := strings.TrimSuffix(filename, ext)
-		dest = "raw/processed/" + date + "/" + base + "-" + time.Now().UTC().Format("150405") + ext
+		dest = filepath.Join(processedDir, base+"-"+time.Now().UTC().Format("150405")+ext)
 	}
-	if err := copyFromRoot(root, rel, cfg.BrainDir, dest); err != nil {
+	if err := copyFromRoot(root, rel, dest); err != nil {
 		return fmt.Errorf("copy to processed: %w", err)
 	}
-	if err := putBrainFile(cfg.BrainDir, "raw/"+filepath.ToSlash(rel)+".processed", []byte(date)); err != nil {
+	if err := os.WriteFile(path+".processed", []byte(date), 0o644); err != nil {
 		slog.Error("watcher: failed to write .processed marker", "error", err)
 	}
 
@@ -208,22 +214,23 @@ func appendWatcherLog(brainDir, filename string, runErr error, date string) erro
 	entry := fmt.Sprintf("## %s — watcher error\n\n- **File:** %s\n- **Error:** %s\n\n",
 		date, filename, runErr.Error())
 
-	if err := brainfs.AppendFile(brainDir, "log.md", []byte(entry)); err != nil {
-		return fmt.Errorf("write log: %w", err)
-	}
-	return nil
+	logPath := filepath.Join(brainDir, "log.md")
+	f, err := os.OpenFile(logPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)
+	if err != nil {
+		return fmt.Errorf("open log: %w", err)
 	}
 
-// putBrainFile creates or replaces a brain-relative file through the brain
-// root, never through a symlinked directory or file (hyperguild#158).
-func putBrainFile(brainDir, rel string, data []byte) error {
-	return brainfs.PutFile(brainDir, rel, data)
+	if _, err = f.WriteString(entry); err != nil {
+		f.Close() //nolint:errcheck
+		return fmt.Errorf("write log: %w", err)
+	}
+	return f.Close()
 }
 
 // copyFromRoot archives a raw/ file read through the root, refusing anything
 // that is not a regular file, so a swapped-in symlink cannot copy an outside
 // file into raw/processed/ or raw/failed/ (hyperguild#153).
-func copyFromRoot(root *os.Root, rel, brainDir, dstRel string) error {
+func copyFromRoot(root *os.Root, rel, dst string) error {
 	fi, err := root.Lstat(rel)
 	if err != nil {
 		return err
@@ -236,9 +243,13 @@ func copyFromRoot(root *os.Root, rel, brainDir, dstRel string) error {
 		return err
 	}
 	defer func() { _ = in.Close() }()
-	data, err := io.ReadAll(in)
+	out, err := os.Create(dst)
 	if err != nil {
 		return err
 	}
-	return putBrainFile(brainDir, dstRel, data)
+	if _, err := io.Copy(out, in); err != nil {
+		_ = out.Close()
+		return err
+	}
+	return out.Close()
 }

ingestion/internal/watcher/writes_redirect_test.go

@@ -1,66 +0,0 @@
-package watcher
-
-import (
-	"context"
-	"encoding/json"
-	"errors"
-	"os"
-	"path/filepath"
-	"testing"
-	"time"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-
-	"github.com/mathiasbq/hyperguild/ingestion/internal/pipeline"
-)
-
-func okPipeline() pipeline.Config {
-	return pipeline.Config{Complete: func(context.Context, string, string) (string, error) {
-		b, _ := json.Marshal([]pipeline.RawPage{{Title: "X", Type: "source", Subtype: "article", Content: "## S\n\nx\n"}})
-		return string(b), nil
-	}, Schema: "# Schema"}
-}
-
-func failingPipeline() pipeline.Config {
-	return pipeline.Config{Complete: func(context.Context, string, string) (string, error) {
-		return "", errors.New("model down")
-	}, Schema: "# Schema"}
-}
-
-// hyperguild#158: the watcher wrote the archive copy under raw/processed or
-// raw/failed, and its log.md entry, by path, so a symlinked archive
-// directory or log redirected the write elsewhere in the brain or outside
-// it. (A pre-planted marker symlink makes the watcher skip the note, so the
-// marker write itself is reachable only by a race.)
-func TestProcessDirDoesNotWriteThroughASymlinkedArchiveDirOrLog(t *testing.T) {
-	for name, pcfg := range map[string]pipeline.Config{"processed": okPipeline(), "failed": failingPipeline()} {
-		t.Run(name, func(t *testing.T) {
-			brainDir := setupBrainDir(t)
-			outside := t.TempDir()
-			victim := filepath.Join(brainDir, "wiki", "concepts", "v.md")
-			require.NoError(t, os.WriteFile(victim, []byte("untouched"), 0o644))
-			require.NoError(t, os.WriteFile(filepath.Join(brainDir, "raw", "n.md"), []byte("note"), 0o644))
-			require.NoError(t, os.Symlink(outside, filepath.Join(brainDir, "raw", name)))
-			if name == "failed" {
-				require.NoError(t, os.Symlink(filepath.Join("wiki", "concepts", "v.md"), filepath.Join(brainDir, "log.md")))
-			}
-			_ = processDir(context.Background(), Config{BrainDir: brainDir, Interval: time.Hour, Pipeline: pcfg}, "2026-10-05")
-			got, _ := os.ReadFile(victim)
-			assert.Equal(t, "untouched", string(got), "the log was written through a symlink")
-			ents, _ := os.ReadDir(outside)
-			assert.Empty(t, ents, "the archive copy was written outside the brain")
-		})
-	}
-}
-
-func TestProcessDirWritesMarkersAndArchiveInRealDirectories(t *testing.T) {
-	brainDir := setupBrainDir(t)
-	require.NoError(t, os.WriteFile(filepath.Join(brainDir, "raw", "n.md"), []byte("note"), 0o644))
-	errs := processDir(context.Background(), Config{BrainDir: brainDir, Interval: time.Hour, Pipeline: okPipeline()}, "2026-10-05")
-	assert.Empty(t, errs)
-	_, err := os.Stat(filepath.Join(brainDir, "raw", "n.md.processed"))
-	assert.NoError(t, err, "positive control: marker written")
-	_, err = os.Stat(filepath.Join(brainDir, "raw", "processed", "2026-10-05", "n.md"))
-	assert.NoError(t, err, "positive control: archive copy written")
-}