test(tunnel): pin the raced read, the walk error and the _index.md skip (#174)

Review round 1 on PR #186:

- The swap test's static note had the same title as the raced note, so
  the harness's "inside was read" floor passed without reading r.md
  (skipping r.md stayed green). The static note now has its own title.
- An unreadable directory under wiki/ reaches the walk-error path, and
  swallowing that error stayed green. New test asserts the error.
- The FIFO test now runs with and without a writer held open.
- _index.md skip had no test; new test.
- index.go: the double blank line left by removing readTitleAndCreated.

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

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/go.mod

@@ -68,7 +68,7 @@ require (
 	github.com/segmentio/asm v1.2.0 // indirect
 	golang.org/x/crypto v0.51.0 // indirect
 	golang.org/x/sync v0.21.0 // indirect
-	golang.org/x/sys v0.45.0
+	golang.org/x/sys v0.45.0 // indirect
 	golang.org/x/text v0.39.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1
 )

ingestion/internal/api/readnote_root_test.go

@@ -23,13 +23,6 @@ func TestReadNoteRefusesSymlinksAndSurvivesSwapRaces(t *testing.T) {
 	_, body, _, err := api.ReadNote(brain, "wiki/w/facts/leak.md")
 	assert.Error(t, err)
 	assert.NotContains(t, body, brainfstest.Sentinel)
-	// A link to a file elsewhere in the brain: os.Root allows it, only the
-	// regular-file check refuses it (hyperguild#171).
-	brainfstest.WriteSentinelAt(t, filepath.Join(brain, "raw", "s.md"))
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "..", "raw", "s.md"), filepath.Join(facts, "inlink.md")))
-	_, body, _, err = api.ReadNote(brain, "wiki/w/facts/inlink.md")
-	assert.Error(t, err)
-	assert.NotContains(t, body, brainfstest.Sentinel)
 
 	p := filepath.Join(facts, "r.md")
 	require.NoError(t, os.WriteFile(p, []byte("---\nx: y\n---\ninside"), 0o644))
@@ -46,7 +39,5 @@ func TestReadNoteRefusesSymlinksAndSurvivesSwapRaces(t *testing.T) {
 		return s
 	}
 	brainfstest.AssertNoLeak(t, p, "---\nx: y\n---\ninside", 1500*time.Millisecond, read)
-	inBrain := brainfstest.WriteSentinelAt(t, filepath.Join(brain, "raw", "s.md"))
-	brainfstest.AssertNoLeakFrom(t, p, "---\nx: y\n---\ninside", inBrain, 1500*time.Millisecond, read)
 	brainfstest.AssertNoHang(t, p, "---\nx: y\n---\ninside", 1500*time.Millisecond, 6*time.Second, func() { _ = read() })
 }

ingestion/internal/api/update_redirect_test.go

@@ -1,36 +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"
-	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs"
-)
-
-// hyperguild#173: a directory symlink inside wiki/ that points elsewhere in
-// the brain redirected brain_update's write (os.Root follows in-root
-// intermediate symlinks). Every directory above the note must be real.
-func TestUpdateNoteRefusesANoteBehindASymlinkedDirectory(t *testing.T) {
-	brain := t.TempDir()
-	victim := filepath.Join(brain, "raw", "facts", "v.md")
-	require.NoError(t, os.MkdirAll(filepath.Dir(victim), 0o755))
-	require.NoError(t, os.WriteFile(victim, []byte("---\ntitle: v\n---\nuntouched\n"), 0o644))
-	require.NoError(t, os.MkdirAll(filepath.Join(brain, "wiki", "w"), 0o755))
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "raw", "facts"), filepath.Join(brain, "wiki", "w", "alias")))
-
-	_, _, _, err := api.UpdateNote(brain, api.UpdateNoteOptions{Path: "wiki/w/alias/v.md", Content: "replaced"})
-	assert.ErrorIs(t, err, brainfs.ErrNotRegular)
-	got, _ := os.ReadFile(victim)
-	assert.Contains(t, string(got), "untouched")
-
-	real := filepath.Join(brain, "wiki", "w", "facts", "r.md")
-	require.NoError(t, os.MkdirAll(filepath.Dir(real), 0o755))
-	require.NoError(t, os.WriteFile(real, []byte("---\ntitle: r\n---\nold\n"), 0o644))
-	_, _, _, err = api.UpdateNote(brain, api.UpdateNoteOptions{Path: "wiki/w/facts/r.md", Content: "new"})
-	require.NoError(t, err, "positive control: a note in a real directory is updated")
-}

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/brain/tunnel_redirect_test.go

@@ -1,38 +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"
-	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs"
-)
-
-// hyperguild#173: brain_tunnel's write followed a directory symlink inside
-// wiki/ that points elsewhere in the brain.
-func TestWriteTunnelRefusesATargetBehindASymlinkedDirectory(t *testing.T) {
-	b := t.TempDir()
-	src := filepath.Join(b, "wiki", "a", "facts", "s.md")
-	require.NoError(t, os.MkdirAll(filepath.Dir(src), 0o755))
-	require.NoError(t, os.WriteFile(src, []byte("x\n"), 0o644))
-	victim := filepath.Join(b, "raw", "facts", "v.md")
-	require.NoError(t, os.MkdirAll(filepath.Dir(victim), 0o755))
-	require.NoError(t, os.WriteFile(victim, []byte("untouched\n"), 0o644))
-	require.NoError(t, os.MkdirAll(filepath.Join(b, "wiki", "b"), 0o755))
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "raw", "facts"), filepath.Join(b, "wiki", "b", "facts")))
-
-	assert.ErrorIs(t, brain.WriteTunnel(b, "wiki/a/facts/s.md", "wiki/b/facts/v.md"), brainfs.ErrNotRegular)
-	got, _ := os.ReadFile(victim)
-	assert.Equal(t, "untouched\n", string(got))
-	got, _ = os.ReadFile(src)
-	assert.Equal(t, "x\n", string(got), "the source is not rewritten either")
-
-	real := filepath.Join(b, "wiki", "c", "facts", "t.md")
-	require.NoError(t, os.MkdirAll(filepath.Dir(real), 0o755))
-	require.NoError(t, os.WriteFile(real, []byte("t\n"), 0o644))
-	require.NoError(t, brain.WriteTunnel(b, "wiki/a/facts/s.md", "wiki/c/facts/t.md"), "positive control: a tunnel between real directories is written")
-}

ingestion/internal/brainfs/brainfs.go

@@ -104,17 +104,6 @@ func (b *Brain) ReadDirRegular(relDir string) ([]string, error) {
 	return names, nil
 }
 
-// cleanRel refuses a path that is not clean and local. realDir checks the
-// cleaned parent, so the I/O must use that same path: os.Root resolves ".."
-// after following a symlink, and a ".." after a symlinked directory would
-// otherwise pass the check and redirect the read or write.
-func cleanRel(rel string) error {
-	if rel == "" || path.Clean(rel) != rel || !filepath.IsLocal(rel) || strings.Contains(rel, "\\") {
-		return fmt.Errorf("%q: not a clean brain-relative path: %w", rel, ErrNotRegular)
-	}
-	return nil
-}
-
 // ReadDirDirs lists the real subdirectories directly in a brain-relative
 // directory, by name. Every component of relDir must be a real directory
 // (ErrNotRegular otherwise); symlinks to directories are left out.
@@ -136,58 +125,9 @@ func (b *Brain) ReadDirDirs(relDir string) ([]string, error) {
 	return names, nil
 }
 
-// OpenLock opens (creating if absent) a regular lock file at a clean
-// brain-relative path for flock, through the root (hyperguild#192): every
-// directory above it must be real, an existing lock must be a regular file,
-// and the opened handle must be the file at the path (os.Root follows an
-// in-root final symlink even with O_NOFOLLOW). A dangling or swapped-in
-// symlink is refused; nothing is created at its target.
-func (b *Brain) OpenLock(rel string) (*os.File, error) {
-	if err := cleanRel(rel); err != nil {
-		return nil, err
-	}
-	if err := b.realDir(path.Dir(rel)); err != nil {
-		return nil, err
-	}
-	if fi, err := b.root.Lstat(rel); err == nil && !fi.Mode().IsRegular() {
-		return nil, fmt.Errorf("%s: %w", rel, ErrNotRegular)
-	} else if err != nil && !errors.Is(err, fs.ErrNotExist) {
-		return nil, err
-	}
-	f, err := b.root.OpenFile(rel, os.O_RDWR|os.O_CREATE|syscall.O_NOFOLLOW|syscall.O_NONBLOCK, 0o644)
-	if err != nil {
-		return nil, err
-	}
-	hfi, herr := f.Stat()
-	lfi, lerr := b.root.Lstat(rel)
-	if herr != nil || lerr != nil || !lfi.Mode().IsRegular() || !os.SameFile(lfi, hfi) {
-		_ = f.Close()
-		return nil, fmt.Errorf("%s: changed while opening: %w", rel, ErrNotRegular)
-	}
-	return f, nil
-}
-
-// RemoveLock removes the lock file at rel through the root (a symlink there
-// is removed itself, never its target).
-func (b *Brain) RemoveLock(rel string) error {
-	if err := cleanRel(rel); err != nil {
-		return err
-	}
-	if err := b.realDir(path.Dir(rel)); err != nil {
-		return err
-	}
-	return b.root.Remove(rel)
-}
-
 // ReadRegular reads a brain-relative path, refusing anything that is not a
 // regular file, both before the open and on the opened handle.
 func (b *Brain) ReadRegular(rel string) ([]byte, error) {
-	if err := cleanRel(rel); err != nil {
-		return nil, err
-	}
-	if err := b.realDir(path.Dir(rel)); err != nil {
-		return nil, err
-	}
 	fi, err := b.root.Lstat(rel)
 	if err != nil {
 		return nil, err
@@ -214,12 +154,6 @@ func (b *Brain) readOpened(rel string) ([]byte, error) { return b.readOpenedMax(
 // ReadRegularMax is ReadRegular with a size limit, checked on the opened
 // handle before reading (max < 0 means no limit).
 func (b *Brain) ReadRegularMax(rel string, max int64) ([]byte, error) {
-	if err := cleanRel(rel); err != nil {
-		return nil, err
-	}
-	if err := b.realDir(path.Dir(rel)); err != nil {
-		return nil, err
-	}
 	fi, err := b.root.Lstat(rel)
 	if err != nil {
 		return nil, err
@@ -322,20 +256,10 @@ func (b *Brain) WalkRegular(relDir string, fn func(rel string) error, onErr func
 // O_NOFOLLOW (verified on go1.27), so the path is Lstat-ed through the root
 // first and the opened handle must be that same file (os.SameFile), which
 // also catches a swap between the two. O_NONBLOCK keeps a FIFO from blocking
-// the open. Every directory above the file must be a real directory
-// (hyperguild#173); a directory swapped in after that check is the #167
-// residual.
+// the open. Intermediate in-brain symlinks are still followed (os.Root keeps
+// the write inside the brain; hyperguild#167).
 func (b *Brain) WriteRegular(rel string, data []byte) error {
-	if err := cleanRel(rel); err != nil {
-		return err
-	}
-	// Every directory above the file must be real: os.Root follows an
-	// in-brain intermediate symlink, which would redirect the write
-	// elsewhere in the brain (hyperguild#173). A swap after this check is
-	// the #167 residual.
-	if err := b.realDir(path.Dir(rel)); err != nil {
-		return err
-	}
+	rel = filepath.ToSlash(rel)
 	lfi, err := b.root.Lstat(rel)
 	if err != nil {
 		return err

ingestion/internal/brainfs/brainfs_test.go

@@ -218,7 +218,7 @@ func TestReadDirRegularListsOnlyRegularFilesAndRefusesSymlinkedComponents(t *tes
 // A final component swapped for a symlink to another regular file in the
 // brain between the Lstat and the open: os.Root follows in-root links, so
 // only comparing the two (os.SameFile) refuses it.
-func TestReadRegularDoesNotReturnAnInBrainFileSwappedInBehindASymlink(t *testing.T) {
+func TestReadRegularNeverReturnsAnInBrainFileSwappedInBehindASymlink(t *testing.T) {
 	dir := t.TempDir()
 	require.NoError(t, os.WriteFile(filepath.Join(dir, "s.md"), []byte("zqsamefilesentinel"), 0o644))
 	p := filepath.Join(dir, "r.md")
@@ -326,53 +326,3 @@ func TestReadDirDirsListsOnlyRealSubdirsAndRefusesSymlinkedComponents(t *testing
 	_, err = b.ReadDirDirs("alias")
 	assert.ErrorIs(t, err, ErrNotRegular)
 }
-
-// hyperguild#173: a file reached through a symlinked directory inside the
-// brain is refused for reads and writes, so a caller-supplied path cannot be
-// redirected to another part of the brain.
-func TestReadAndWriteRegularRefuseAFileBehindASymlinkedDirectory(t *testing.T) {
-	dir := t.TempDir()
-	require.NoError(t, os.MkdirAll(filepath.Join(dir, "raw"), 0o755))
-	require.NoError(t, os.WriteFile(filepath.Join(dir, "raw", "v.md"), []byte("untouched"), 0o644))
-	require.NoError(t, os.MkdirAll(filepath.Join(dir, "wiki"), 0o755))
-	require.NoError(t, os.Symlink(filepath.Join("..", "raw"), filepath.Join(dir, "wiki", "alias")))
-	b, err := Open(dir)
-	require.NoError(t, err)
-	defer func() { _ = b.Close() }()
-
-	_, err = b.ReadRegular("wiki/alias/v.md")
-	assert.ErrorIs(t, err, ErrNotRegular)
-	_, err = b.ReadRegularMax("wiki/alias/v.md", 100)
-	assert.ErrorIs(t, err, ErrNotRegular)
-	assert.ErrorIs(t, b.WriteRegular("wiki/alias/v.md", []byte("x")), ErrNotRegular)
-	got, _ := os.ReadFile(filepath.Join(dir, "raw", "v.md"))
-	assert.Equal(t, "untouched", string(got))
-	got, err = b.ReadRegular("raw/v.md")
-	require.NoError(t, err, "positive control: the real path still reads")
-	assert.Equal(t, "untouched", string(got))
-}
-
-// realDir checks the cleaned parent, so the I/O must use that same clean
-// path: os.Root resolves ".." after following a symlink, and a ".." placed
-// after a symlinked directory would otherwise pass the check and redirect.
-func TestReadAndWriteRegularRefuseAPathThatIsNotClean(t *testing.T) {
-	dir := t.TempDir()
-	require.NoError(t, os.MkdirAll(filepath.Join(dir, "raw", "facts"), 0o755))
-	require.NoError(t, os.WriteFile(filepath.Join(dir, "raw", "v.md"), []byte("untouched"), 0o644))
-	require.NoError(t, os.MkdirAll(filepath.Join(dir, "wiki"), 0o755))
-	require.NoError(t, os.Symlink(filepath.Join("..", "raw", "facts"), filepath.Join(dir, "wiki", "alias")))
-	b, err := Open(dir)
-	require.NoError(t, err)
-	defer func() { _ = b.Close() }()
-
-	for _, rel := range []string{"wiki/alias/../v.md", "./raw/v.md", "raw//v.md", "/raw/v.md"} {
-		got, err := b.ReadRegular(rel)
-		assert.ErrorIs(t, err, ErrNotRegular, rel)
-		assert.NotContains(t, string(got), "untouched", rel)
-		_, err = b.ReadRegularMax(rel, 100)
-		assert.ErrorIs(t, err, ErrNotRegular, rel)
-		assert.ErrorIs(t, b.WriteRegular(rel, []byte("OVERWRITTEN")), ErrNotRegular, rel)
-	}
-	got, _ := os.ReadFile(filepath.Join(dir, "raw", "v.md"))
-	assert.Equal(t, "untouched", string(got))
-}

ingestion/internal/brainfs/brainfstest/brainfstest.go

@@ -1,10 +1,8 @@
 // Package brainfstest is the shared harness for hyperguild#157's swap-race
-// tests: it keeps swapping a regular note, a symlink to a sentinel target file
-// (outside the brain, or inside it for hyperguild#171), or a FIFO (with a
-// writer held open) into a path while a reader under test loops.
-// It observes two things, over a sampled window only: no sentinel byte from
-// the target reaches the reader's output, and the reader returns within a
-// timeout. It does not cover
+// tests: it keeps swapping a regular note, a symlink to an outside file, or a
+// FIFO (with a writer held open) into a path while a reader under test loops.
+// It observes two things: no sentinel byte from the outside file reaches the
+// reader's output, and the reader returns within a timeout. It does not cover
 // hard links, other paths into the reader, or races it does not generate.
 package brainfstest
 
@@ -20,7 +18,7 @@ import (
 	"time"
 )
 
-// Sentinel marks the target file's contents.
+// Sentinel marks the outside file's contents.
 const Sentinel = "zqbrainfssentinelonefiftyseven"
 
 // outsideContent carries Sentinel in every field a reader might extract: the
@@ -143,7 +141,7 @@ func AssertNoLeakFrom(t testing.TB, path, inside, target string, d time.Duration
 		}
 	}
 	if leaks > 0 {
-		t.Fatalf("symlink target %s leaked %d times in %d iterations", target, leaks, iters)
+		t.Fatalf("outside file leaked %d times in %d iterations", leaks, iters)
 	}
 	if n := swaps.Load(); n == 0 {
 		t.Fatalf("no symlink was swapped into %s in %d iterations: the race did not run", path, iters)

ingestion/internal/classification/classification.go

@@ -16,10 +16,9 @@
 package classification
 
 import (
-	"errors"
 	"fmt"
-	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs"
-	"io/fs"
+	"os"
+	"path/filepath"
 	"strings"
 
 	"gopkg.in/yaml.v3"
@@ -111,20 +110,9 @@ type rawConfig struct {
 func Load(brainDir string) (*Config, error) {
 	cfg := &Config{wings: map[string]Level{}, repos: map[string]Level{}}
 
-	// Read through the brain root, regular files only (hyperguild#157): a
-	// symlinked or special file is not trusted as the config, which is a hard
-	// error like a malformed one.
-	bfs, err := brainfs.Open(brainDir)
-	if errors.Is(err, fs.ErrNotExist) {
-		return cfg, nil
-	}
+	data, err := os.ReadFile(filepath.Join(brainDir, "classification.yaml"))
 	if err != nil {
-		return nil, fmt.Errorf("open brain: %w", err)
-	}
-	defer func() { _ = bfs.Close() }()
-	data, err := bfs.ReadRegular("classification.yaml")
-	if err != nil {
-		if errors.Is(err, fs.ErrNotExist) {
+		if os.IsNotExist(err) {
 			return cfg, nil
 		}
 		return nil, fmt.Errorf("read classification.yaml: %w", err)

ingestion/internal/classification/root_test.go

@@ -1,46 +0,0 @@
-package classification
-
-import (
-	"os"
-	"path/filepath"
-	"syscall"
-	"testing"
-	"time"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-// hyperguild#157 slice 6: Load read classification.yaml with os.ReadFile. It
-// sets the I1 sovereignty levels; a symlinked file must not be trusted as the
-// config (a hard error, as for a malformed file), and a FIFO must not hang
-// startup.
-func TestLoadRefusesASymlinkedOrFIFOClassificationFile(t *testing.T) {
-	ok := t.TempDir()
-	require.NoError(t, os.WriteFile(filepath.Join(ok, "classification.yaml"), []byte("wings:\n  w: confidential\n"), 0o644))
-	_, err := Load(ok)
-	require.NoError(t, err, "positive control")
-
-	linked := t.TempDir()
-	require.NoError(t, os.WriteFile(filepath.Join(linked, "real.yaml"), []byte("wings:\n  w: public\n"), 0o644))
-	require.NoError(t, os.Symlink("real.yaml", filepath.Join(linked, "classification.yaml")))
-	_, err = Load(linked)
-	assert.Error(t, err, "an in-brain symlink is not trusted as the config")
-
-	fifo := t.TempDir()
-	require.NoError(t, syscall.Mkfifo(filepath.Join(fifo, "classification.yaml"), 0o644))
-	w, err := os.OpenFile(filepath.Join(fifo, "classification.yaml"), os.O_RDWR, 0)
-	require.NoError(t, err)
-	defer func() { _ = w.Close() }()
-	done := make(chan error, 1)
-	go func() { _, err := Load(fifo); done <- err }()
-	select {
-	case err := <-done:
-		assert.Error(t, err)
-	case <-time.After(3 * time.Second):
-		t.Fatal("Load hung on a FIFO")
-	}
-
-	_, err = Load(t.TempDir())
-	assert.NoError(t, err, "an absent file is still not an error")
-}

ingestion/internal/mcp/edit_pathio_test.go

@@ -1,61 +0,0 @@
-package mcp_test
-
-import (
-	"os"
-	"path/filepath"
-	"syscall"
-	"testing"
-	"time"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-
-	"github.com/mathiasbq/hyperguild/ingestion/internal/mcp"
-)
-
-// hyperguild#192: brain_edit snapshotted the note with os.ReadFile by path,
-// which blocks on a FIFO held open by a writer, and hung the call.
-func TestBrainEditReturnsPromptlyOnAFIFONoteWithAWriter(t *testing.T) {
-	dir := newBrainRepo(t)
-	fifo := filepath.Join(dir, "wiki", "homelab", "facts", "f.md")
-	require.NoError(t, syscall.Mkfifo(fifo, 0o644))
-	w, err := os.OpenFile(fifo, os.O_RDWR, 0)
-	require.NoError(t, err)
-	t.Cleanup(func() { _ = w.Close() })
-	srv := mcp.NewServer(dir, nil, nil, nil)
-
-	done := make(chan map[string]any, 1)
-	go func() {
-		done <- call(t, srv, "brain_edit", map[string]any{"path": "wiki/homelab/facts/f.md", "old_str": "a", "new_str": "b"})
-	}()
-	select {
-	case resp := <-done:
-		assert.Contains(t, resp, "error", "a FIFO note is refused")
-	case <-time.After(3 * time.Second):
-		t.Fatal("brain_edit hung on a FIFO note")
-	}
-
-	resp := call(t, srv, "brain_edit", map[string]any{"path": "wiki/homelab/facts/n.md", "old_str": "beta", "new_str": "BETA"})
-	require.NotContains(t, resp, "error", "positive control: a regular note is edited: %v", resp["error"])
-}
-
-// hyperguild#192: the edit lock "<note>.lock" was opened by path with
-// O_CREATE, so a planted dangling .lock symlink made a successful edit create
-// a file at the link's target, outside the brain or elsewhere in it.
-func TestBrainEditDoesNotCreateAFileThroughADanglingLockSymlink(t *testing.T) {
-	for name, target := range map[string]func(t *testing.T, dir string) string{
-		"outside":  func(t *testing.T, _ string) string { return filepath.Join(t.TempDir(), "created") },
-		"in-brain": func(t *testing.T, dir string) string { return filepath.Join(dir, "raw", "created") },
-	} {
-		t.Run(name, func(t *testing.T) {
-			dir := newBrainRepo(t)
-			require.NoError(t, os.MkdirAll(filepath.Join(dir, "raw"), 0o755))
-			tgt := target(t, dir)
-			require.NoError(t, os.Symlink(tgt, filepath.Join(dir, "wiki", "homelab", "facts", "n.md.lock")))
-			srv := mcp.NewServer(dir, nil, nil, nil)
-			_ = call(t, srv, "brain_edit", map[string]any{"path": "wiki/homelab/facts/n.md", "old_str": "beta", "new_str": "BETA"})
-			_, err := os.Lstat(tgt)
-			assert.True(t, os.IsNotExist(err), "a file was created at the lock symlink's target")
-		})
-	}
-}

ingestion/internal/mcp/readexcerpt_root_test.go

@@ -21,11 +21,6 @@ func TestReadExcerptRefusesSymlinksAndSurvivesSwapRaces(t *testing.T) {
 	require.NoError(t, os.MkdirAll(facts, 0o755))
 	require.NoError(t, os.Symlink(brainfstest.Outside(t), filepath.Join(facts, "leak.md")))
 	assert.NotContains(t, readExcerpt(brain, "wiki/w/facts/leak.md", 500), brainfstest.Sentinel)
-	// A link to a file elsewhere in the brain: os.Root allows it, only the
-	// regular-file check refuses it (hyperguild#171).
-	inBrain := brainfstest.WriteSentinelAt(t, filepath.Join(brain, "raw", "s.md"))
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "..", "raw", "s.md"), filepath.Join(facts, "inlink.md")))
-	assert.NotContains(t, readExcerpt(brain, "wiki/w/facts/inlink.md", 500), brainfstest.Sentinel)
 
 	p := filepath.Join(facts, "r.md")
 	require.NoError(t, os.WriteFile(p, []byte("---\nx: y\n---\ninside"), 0o644))
@@ -33,9 +28,6 @@ func TestReadExcerptRefusesSymlinksAndSurvivesSwapRaces(t *testing.T) {
 	brainfstest.AssertNoLeak(t, p, "---\nx: y\n---\ninside", 1500*time.Millisecond, func() string {
 		return readExcerpt(brain, "wiki/w/facts/r.md", 500)
 	})
-	brainfstest.AssertNoLeakFrom(t, p, "---\nx: y\n---\ninside", inBrain, 1500*time.Millisecond, func() string {
-		return readExcerpt(brain, "wiki/w/facts/r.md", 500)
-	})
 	brainfstest.AssertNoHang(t, p, "---\nx: y\n---\ninside", 1500*time.Millisecond, 6*time.Second, func() {
 		_ = readExcerpt(brain, "wiki/w/facts/r.md", 500)
 	})

ingestion/internal/mcp/tools_notes.go

@@ -6,8 +6,8 @@ import (
 	"errors"
 	"fmt"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/api"
-	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs"
 	"log/slog"
+	"os"
 	"strings"
 	"time"
 
@@ -118,14 +118,7 @@ func (s *Server) brainEdit(ctx context.Context, args json.RawMessage) (json.RawM
 		return nil, err
 	}
 	// No snapshot, no edit: without one a failed stamp could not be undone.
-	// Read through the brain root, regular files only (hyperguild#192): a
-	// FIFO held open by a writer hung os.ReadFile.
-	bfs, err := brainfs.Open(s.brainDir)
-	if err != nil {
-		return nil, fmt.Errorf("snapshot before edit: %w", err)
-	}
-	defer func() { _ = bfs.Close() }()
-	prior, err := bfs.ReadRegular(target.Rel)
+	prior, err := os.ReadFile(target.Abs)
 	if err != nil {
 		return nil, fmt.Errorf("snapshot before edit: %w", err)
 	}
@@ -138,7 +131,7 @@ func (s *Server) brainEdit(ctx context.Context, args json.RawMessage) (json.RawM
 	// to the editor after every edit (PR #147 review, escape E1).
 	origin, writtenBy := provenanceFrom(ctx)
 	if serr := api.StampProvenanceFile(s.brainDir, res.Path, origin, writtenBy); serr != nil {
-		if werr := bfs.WriteRegular(target.Rel, prior); werr != nil {
+		if werr := os.WriteFile(target.Abs, prior, 0o644); werr != nil {
 			// Say exactly what state the note is in: edited, unverified.
 			return nil, fmt.Errorf("stamp provenance failed (%v) AND the edit could NOT be rolled back: %w; "+
 				"%s carries the edit under its previous attribution", serr, werr, res.Path)

ingestion/internal/notes/edit.go

@@ -127,7 +127,7 @@ func Edit(brainDir, path, oldStr, newStr string, scope Scope) (Result, error) {
 	mu.Lock()
 	defer mu.Unlock()
 
-	unlock, err := flockFile(t)
+	unlock, err := flockFile(t.Abs)
 	if err != nil {
 		return Result{}, err
 	}
@@ -220,32 +220,20 @@ func lockFor(abs string) *sync.Mutex {
 }
 
 // flockFile takes an advisory lock covering other processes sharing the
-// hostPath — during a RollingUpdate two ingestion pods do. The lock file is
-// opened and removed through the brain root, never through a symlink
-// (hyperguild#192): a planted dangling "<note>.lock" link made a
-// successful edit create a file at its target.
-func flockFile(t Target) (func(), error) {
-	lockRel := t.Rel + ".lock"
-	bfs, err := brainfs.Open(t.Brain)
+// hostPath — during a RollingUpdate two ingestion pods do.
+func flockFile(abs string) (func(), error) {
+	f, err := os.OpenFile(abs+".lock", os.O_CREATE|os.O_RDWR, 0o644)
 	if err != nil {
-		return nil, fmt.Errorf("notes: lock %s: %w", lockRel, err)
-	}
-	f, err := bfs.OpenLock(lockRel)
-	_ = bfs.Close()
-	if err != nil {
-		return nil, fmt.Errorf("notes: lock %s: %w", lockRel, err)
+		return nil, fmt.Errorf("notes: lock %s: %w", filepath.Base(abs), err)
 	}
 	if err := syscall.Flock(int(f.Fd()), syscall.LOCK_EX); err != nil {
 		_ = f.Close()
-		return nil, fmt.Errorf("notes: flock %s: %w", lockRel, err)
+		return nil, fmt.Errorf("notes: flock %s: %w", filepath.Base(abs), err)
 	}
 	return func() {
 		_ = syscall.Flock(int(f.Fd()), syscall.LOCK_UN)
 		_ = f.Close()
-		if b, err := brainfs.Open(t.Brain); err == nil {
-			_ = b.RemoveLock(lockRel)
-			_ = b.Close()
-		}
+		_ = os.Remove(abs + ".lock")
 	}, nil
 }
 

ingestion/internal/notes/read_root_test.go

@@ -38,31 +38,3 @@ func TestReadScopedRefusesANoteOverMaxNoteBytes(t *testing.T) {
 	_, err := ReadScoped(brain, "wiki/w/facts/big.md", ScopeNotes)
 	assert.ErrorIs(t, err, ErrTooLarge)
 }
-
-// hyperguild#171 (review of #172, finding 1): os.Root alone refuses links that
-// leave the brain, so the outside-target race above stays green for a reader
-// that skips brainfs's Lstat and SameFile checks. An in-brain target (raw/,
-// outside ScopeNotes) is what tells them apart.
-func TestReadScopedDoesNotReturnAnInBrainSymlinkTargetStaticallyOrDuringASampledSwapRace(t *testing.T) {
-	brain := t.TempDir()
-	facts := filepath.Join(brain, "wiki", "w", "facts")
-	require.NoError(t, os.MkdirAll(facts, 0o755))
-	target := brainfstest.WriteSentinelAt(t, filepath.Join(brain, "raw", "s.md"))
-
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "..", "raw", "s.md"), filepath.Join(facts, "inlink.md")))
-	b, err := ReadScoped(brain, "wiki/w/facts/inlink.md", ScopeNotes)
-	assert.Error(t, err, "static in-brain link")
-	assert.NotContains(t, string(b), brainfstest.Sentinel, "static in-brain link")
-
-	p := filepath.Join(facts, "r.md")
-	require.NoError(t, os.WriteFile(p, []byte("inside"), 0o644))
-	b, err = ReadScoped(brain, "wiki/w/facts/r.md", ScopeNotes)
-	require.NoError(t, err)
-	assert.Equal(t, "inside", string(b), "positive control: a regular note reads")
-
-	read := func() string {
-		b, _ := ReadScoped(brain, "wiki/w/facts/r.md", ScopeNotes)
-		return string(b)
-	}
-	brainfstest.AssertNoLeakFrom(t, p, "inside", target, 1500*time.Millisecond, read)
-}

ingestion/internal/pipeline/backfill.go

@@ -3,10 +3,7 @@ package pipeline
 
 import (
 	"context"
-	"errors"
 	"fmt"
-	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs"
-	"io/fs"
 	"os"
 	"path/filepath"
 	"strings"
@@ -26,16 +23,10 @@ func BackfillRefs(ctx context.Context, brainDir string) (int, error) {
 		return 0, fmt.Errorf("load inventory: %w", err)
 	}
 
-	// Listed and read through the brain root, regular files only
-	// (hyperguild#157).
-	bfs, err := brainfs.Open(brainDir)
+	sourcesDir := filepath.Join(brainDir, "wiki", "sources")
+	entries, err := os.ReadDir(sourcesDir)
 	if err != nil {
-		return 0, fmt.Errorf("open brain: %w", err)
-	}
-	defer func() { _ = bfs.Close() }()
-	names, err := bfs.ReadDirRegular("wiki/sources")
-	if err != nil {
-		if errors.Is(err, fs.ErrNotExist) {
+		if os.IsNotExist(err) {
 			return 0, nil
 		}
 		return 0, fmt.Errorf("read sources dir: %w", err)
@@ -46,20 +37,20 @@ func BackfillRefs(ctx context.Context, brainDir string) (int, error) {
 	// get both refs merged before a single write.
 	pending := make(map[string]wiki.Page)
 
-	for _, name := range names {
+	for _, e := range entries {
 		if ctx.Err() != nil {
 			return 0, ctx.Err()
 		}
-		if !strings.HasSuffix(name, ".md") {
+		if e.IsDir() || !strings.HasSuffix(e.Name(), ".md") {
 			continue
 		}
 
-		b, err := bfs.ReadRegular("wiki/sources/" + name)
+		b, err := os.ReadFile(filepath.Join(sourcesDir, e.Name()))
 		if err != nil {
 			continue
 		}
 		sourceContent := string(b)
-		sourceSlug := strings.TrimSuffix(name, ".md")
+		sourceSlug := strings.TrimSuffix(e.Name(), ".md")
 		sourceTitle := extractTitle(sourceContent)
 		if sourceTitle == "" {
 			sourceTitle = sourceSlug
@@ -79,7 +70,7 @@ func BackfillRefs(ctx context.Context, brainDir string) (int, error) {
 			// Start from already-accumulated version if we've seen this page.
 			page, seen := pending[relPath]
 			if !seen {
-				raw, err := bfs.ReadRegular(relPath)
+				raw, err := os.ReadFile(filepath.Join(brainDir, filepath.FromSlash(relPath)))
 				if err != nil {
 					continue
 				}

ingestion/internal/pipeline/pipeline.go

@@ -5,10 +5,7 @@ import (
 	"context"
 	"crypto/sha256"
 	"encoding/hex"
-	"errors"
 	"fmt"
-	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs"
-	"io/fs"
 	"os"
 	"path/filepath"
 	"strings"
@@ -132,7 +129,7 @@ func buildAndWrite(ctx context.Context, rawPages []RawPage, sourceSlug, date, br
 			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)
+			content, conflicts, err := reviseOrCreate(dest, page)
 			if err != nil {
 				return Result{}, err
 			}
@@ -191,27 +188,14 @@ func hashBody(content string) string {
 
 // readSourcePage returns the full on-disk content of the source page at
 // wiki/sources/<sourceSlug>.md, or "" when it doesn't exist yet.
-// It reads through the brain root, regular files only (hyperguild#157): the
-// content goes into the LLM prompt.
 func readSourcePage(brainDir, sourceSlug string) string {
-	raw, err := readBrainFile(brainDir, "wiki/sources/"+sourceSlug+".md")
+	raw, err := os.ReadFile(filepath.Join(brainDir, "wiki", "sources", sourceSlug+".md"))
 	if err != nil {
 		return ""
 	}
 	return string(raw)
 }
 
-// readBrainFile reads one brain-relative file through the brain root,
-// regular files only (hyperguild#157).
-func readBrainFile(brainDir, rel string) ([]byte, error) {
-	bfs, err := brainfs.Open(brainDir)
-	if err != nil {
-		return nil, err
-	}
-	defer func() { _ = bfs.Close() }()
-	return bfs.ReadRegular(rel)
-}
-
 // storedSourceHash reads source_hash from the source page a previous ingest
 // wrote, or "" when there is no such page or no such field.
 //
@@ -246,10 +230,10 @@ func storedSourceHash(brainDir, sourceSlug string) string {
 // its first-ingest date on a revised page. Left deliberately — the alternative
 // is this function editing frontmatter it does not own, and no lint reads that
 // field today.
-func reviseOrCreate(brainDir string, page wiki.Page) (string, []string, error) {
-	existing, err := readBrainFile(brainDir, page.Path)
+func reviseOrCreate(dest string, page wiki.Page) (string, []string, error) {
+	existing, err := os.ReadFile(dest)
 	switch {
-	case errors.Is(err, fs.ErrNotExist):
+	case os.IsNotExist(err):
 		return page.Content, nil, nil
 	case err != nil:
 		return "", nil, fmt.Errorf("read existing %s: %w", page.Path, err)
@@ -283,7 +267,7 @@ See brain/schema.md for the full schema.
 `
 
 func loadSchema(brainDir string) string {
-	b, err := readBrainFile(brainDir, "schema.md")
+	b, err := os.ReadFile(filepath.Join(brainDir, "schema.md"))
 	if err != nil {
 		return defaultSchema
 	}

ingestion/internal/pipeline/refs.go

@@ -2,6 +2,7 @@
 package pipeline
 
 import (
+	"os"
 	"path/filepath"
 	"regexp"
 	"strings"
@@ -52,7 +53,8 @@ func injectSourceRefs(pages []wiki.Page, inventory map[wiki.PageType][]wiki.Entr
 		if !ok {
 			continue
 		}
-		b, err := readBrainFile(brainDir, "wiki/"+string(pt)+"/"+slug+".md")
+		diskPath := filepath.Join(brainDir, "wiki", string(pt), slug+".md")
+		b, err := os.ReadFile(diskPath)
 		if err != nil {
 			continue
 		}

ingestion/internal/pipeline/root_test.go

@@ -1,167 +0,0 @@
-package pipeline
-
-import (
-	"context"
-	"fmt"
-	"io"
-	"os"
-	"path/filepath"
-	"syscall"
-	"testing"
-	"time"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-
-	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs/brainfstest"
-	"github.com/mathiasbq/hyperguild/ingestion/internal/wiki"
-)
-
-// hyperguild#157 slice 6: the pipeline read the source page, schema.md, the
-// pages it revises and the pages it adds source refs to with os.ReadFile, so
-// a symlinked file's content reached the LLM prompt and the written pages,
-// and a FIFO hung the ingest.
-
-func mkdirs(t *testing.T, brain string, dirs ...string) {
-	t.Helper()
-	for _, d := range dirs {
-		require.NoError(t, os.MkdirAll(filepath.Join(brain, filepath.FromSlash(d)), 0o755))
-	}
-}
-
-func TestReadSourcePageAndSchemaRefuseSymlinksAndSurviveSwapRaces(t *testing.T) {
-	brain := t.TempDir()
-	mkdirs(t, brain, "wiki/sources")
-	inBrain := brainfstest.WriteSentinelAt(t, filepath.Join(brain, "raw", "s.md"))
-	require.NoError(t, os.WriteFile(filepath.Join(brain, "wiki", "sources", "ok.md"), []byte("zqinside source"), 0o644))
-	require.NoError(t, os.WriteFile(filepath.Join(brain, "schema.md"), []byte("zqinside schema"), 0o644))
-	assert.Equal(t, "zqinside source", readSourcePage(brain, "ok"), "positive control")
-	assert.Equal(t, "zqinside schema", loadSchema(brain), "positive control")
-
-	require.NoError(t, os.Symlink(brainfstest.Outside(t), filepath.Join(brain, "wiki", "sources", "out.md")))
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "raw", "s.md"), filepath.Join(brain, "wiki", "sources", "in.md")))
-	assert.NotContains(t, readSourcePage(brain, "out"), brainfstest.Sentinel)
-	assert.NotContains(t, readSourcePage(brain, "in"), brainfstest.Sentinel)
-	assert.NotContains(t, storedSourceHash(brain, "in"), brainfstest.Sentinel)
-
-	src := filepath.Join(brain, "wiki", "sources", "r.md")
-	read := func() string { return readSourcePage(brain, "r") }
-	brainfstest.AssertNoLeak(t, src, "zqinside", 1500*time.Millisecond, read)
-	brainfstest.AssertNoLeakFrom(t, src, "zqinside", inBrain, 1500*time.Millisecond, read)
-	brainfstest.AssertNoHang(t, src, "zqinside", 1500*time.Millisecond, 6*time.Second, func() { _ = read() })
-
-	schema := filepath.Join(brain, "schema.md")
-	rs := func() string { return loadSchema(brain) }
-	brainfstest.AssertNoLeakFrom(t, schema, "zqinside schema", inBrain, 1500*time.Millisecond, rs)
-	brainfstest.AssertNoHang(t, schema, "zqinside schema", 1500*time.Millisecond, 6*time.Second, func() { _ = rs() })
-}
-
-func TestReviseOrCreateRefusesASymlinkedExistingPage(t *testing.T) {
-	brain := t.TempDir()
-	mkdirs(t, brain, "wiki/concepts")
-	brainfstest.WriteSentinelAt(t, filepath.Join(brain, "raw", "s.md"))
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "raw", "s.md"), filepath.Join(brain, "wiki", "concepts", "c.md")))
-	page := wiki.Page{Path: "wiki/concepts/c.md", Content: "---\ntitle: C\n---\nnew\n"}
-	out, _, err := reviseOrCreate(brain, page)
-	assert.Error(t, err)
-	assert.NotContains(t, out, brainfstest.Sentinel)
-
-	require.NoError(t, os.WriteFile(filepath.Join(brain, "wiki", "concepts", "d.md"), []byte("---\ntitle: D\n---\nzqold\n"), 0o644))
-	out, _, err = reviseOrCreate(brain, wiki.Page{Path: "wiki/concepts/d.md", Content: "---\ntitle: D\n---\nnew\n"})
-	require.NoError(t, err)
-	assert.Contains(t, out, "zqold", "positive control: the existing page is read")
-	out, _, err = reviseOrCreate(brain, wiki.Page{Path: "wiki/concepts/new.md", Content: "fresh"})
-	require.NoError(t, err)
-	assert.Equal(t, "fresh", out, "positive control: a missing page is created")
-}
-
-func TestInjectSourceRefsDoesNotReadASymlinkedPage(t *testing.T) {
-	brain := t.TempDir()
-	mkdirs(t, brain, "wiki/concepts")
-	brainfstest.WriteSentinelAt(t, filepath.Join(brain, "raw", "s.md"))
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "raw", "s.md"), filepath.Join(brain, "wiki", "concepts", "c.md")))
-	require.NoError(t, os.WriteFile(filepath.Join(brain, "wiki", "concepts", "d.md"), []byte("zqinside d"), 0o644))
-	inv := map[wiki.PageType][]wiki.Entry{wiki.PageTypeConcept: {
-		{Slug: "c", Type: wiki.PageTypeConcept}, {Slug: "d", Type: wiki.PageTypeConcept},
-	}}
-	src := wiki.Page{Path: "wiki/sources/src.md", Content: "---\ntitle: Src\n---\nsee [[c|C]] and [[d|D]]\n"}
-	out := injectSourceRefs([]wiki.Page{src}, inv, brain)
-	got := fmt.Sprintf("%+v", out)
-	assert.Contains(t, got, "zqinside d", "positive control")
-	assert.NotContains(t, got, brainfstest.Sentinel)
-}
-
-func TestBackfillRefsSkipsSymlinkedSourcesAndPages(t *testing.T) {
-	brain := t.TempDir()
-	mkdirs(t, brain, "wiki/sources", "wiki/concepts", "raw")
-	require.NoError(t, os.WriteFile(filepath.Join(brain, "wiki", "concepts", "real.md"), []byte("---\ntitle: R\n---\nbody\n"), 0o644))
-	require.NoError(t, os.WriteFile(filepath.Join(brain, "wiki", "sources", "ok.md"), []byte("---\ntitle: zqinside\n---\n[[real|R]]\n"), 0o644))
-	// A source elsewhere in the brain whose title is the sentinel and which
-	// links the real concept with the [[slug|title]] form the pipeline follows.
-	require.NoError(t, os.WriteFile(filepath.Join(brain, "raw", "src.md"),
-		[]byte("---\ntitle: "+brainfstest.Sentinel+"\n---\n[[real|R]]\n"), 0o644))
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "raw", "src.md"), filepath.Join(brain, "wiki", "sources", "in.md")))
-	// A concept page linked by the regular source that is itself a symlink.
-	require.NoError(t, os.WriteFile(filepath.Join(brain, "wiki", "sources", "ok2.md"), []byte("---\ntitle: Two\n---\n[[lnk|L]]\n"), 0o644))
-	brainfstest.WriteSentinelAt(t, filepath.Join(brain, "raw", "page.md"))
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "raw", "page.md"), filepath.Join(brain, "wiki", "concepts", "lnk.md")))
-
-	_, err := BackfillRefs(context.Background(), brain)
-	require.NoError(t, err)
-	b, _ := os.ReadFile(filepath.Join(brain, "wiki", "concepts", "real.md"))
-	assert.Contains(t, string(b), "zqinside", "positive control: the regular source's ref is added")
-	assert.NotContains(t, string(b), brainfstest.Sentinel, "a symlinked source's title was written as a ref")
-	raw, _ := os.ReadFile(filepath.Join(brain, "raw", "page.md"))
-	assert.NotContains(t, string(raw), "[[ok2", "the symlinked concept page's target was rewritten")
-}
-
-// A source swapped between a regular file and a symlink to an in-brain source
-// whose title is the sentinel: the read refuses the swapped-in link, so the
-// sentinel never lands in the concept page as a ref.
-func TestBackfillRefsDoesNotWriteARefFromASourceSwappedInBehindASymlink(t *testing.T) {
-	brain := t.TempDir()
-	mkdirs(t, brain, "wiki/sources", "wiki/concepts", "raw")
-	realPage := filepath.Join(brain, "wiki", "concepts", "real.md")
-	target := filepath.Join(brain, "raw", "src.md")
-	require.NoError(t, os.WriteFile(target, []byte("---\ntitle: "+brainfstest.Sentinel+"\n---\n[[real|R]]\n"), 0o644))
-	src := filepath.Join(brain, "wiki", "sources", "r.md")
-	inside := "---\ntitle: zqinside\n---\n[[real|R]]\n"
-	read := func() string {
-		_ = os.WriteFile(realPage, []byte("---\ntitle: R\n---\nbody\n"), 0o644)
-		_, _ = BackfillRefs(context.Background(), brain)
-		b, _ := os.ReadFile(realPage)
-		return string(b)
-	}
-	require.NoError(t, os.WriteFile(src, []byte(inside), 0o644))
-	require.Contains(t, read(), "zqinside", "positive control")
-	brainfstest.AssertNoLeakFrom(t, src, inside, target, 1500*time.Millisecond, read)
-}
-
-// A concept page that is regular when the inventory lists it, then swapped
-// for a symlink to an in-brain file before BackfillRefs reads it: only the
-// page read's own check refuses it (a static symlink never gets this far,
-// because LoadInventory does not list it).
-func TestBackfillRefsDoesNotCopyAPageSwappedInBehindASymlink(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")
-	inside := "---\ntitle: C\n---\nzqinside\n"
-	read := func() string {
-		// The write path still follows a swapped-in link (#158) and can
-		// overwrite the target, so restore it each round.
-		_ = os.WriteFile(target, []byte("---\ntitle: X\n---\n"+brainfstest.Sentinel+"\n"), 0o644)
-		_, _ = BackfillRefs(context.Background(), brain)
-		f, err := os.OpenFile(page, os.O_RDONLY|syscall.O_NOFOLLOW|syscall.O_NONBLOCK, 0)
-		if err != nil {
-			return ""
-		}
-		defer func() { _ = f.Close() }()
-		b, _ := io.ReadAll(f)
-		return string(b)
-	}
-	require.NoError(t, os.WriteFile(page, []byte(inside), 0o644))
-	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)
-}

ingestion/internal/search/brainroot_test.go

@@ -12,8 +12,6 @@ import (
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
-
-	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs/brainfstest"
 )
 
 // hyperguild#157 option 1: search walked and read the brain by path, so a
@@ -191,49 +189,3 @@ func TestHydrateRefusesASymlink(t *testing.T) {
 	assert.Error(t, err)
 	assert.NotContains(t, r.Excerpt, sentinel157)
 }
-
-// hyperguild#171: os.Root refuses links that leave the brain on its own, so
-// the outside-target cases above would stay green for a caller that read
-// without brainfs's Lstat and SameFile checks. These targets are inside the
-// brain (raw/, which is not a search root).
-func inBrainTarget(t *testing.T, brain string) string {
-	t.Helper()
-	return brainfstest.WriteSentinelAt(t, filepath.Join(brain, "raw", "s.md"))
-}
-
-func TestQueryDoesNotReturnAnInBrainSymlinkTargetDuringASampledSwapRace(t *testing.T) {
-	brain, facts, _ := searchBrain(t)
-	target := inBrainTarget(t, brain)
-	read := func() string {
-		// Both terms, so the regular note is a possible hit: a reader that
-		// never returns the inside note would pass vacuously (#177 floor).
-		rs, _ := Query(brain, QueryOptions{Query: brainfstest.Sentinel + " zqinside", Limit: 10})
-		s := ""
-		for _, r := range rs {
-			s += r.Title + r.Excerpt
-		}
-		return s
-	}
-	brainfstest.AssertNoLeakFrom(t, filepath.Join(facts, "r.md"), "# r\n\nzqinside", target, 1500*time.Millisecond, read)
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "..", "raw", "s.md"), filepath.Join(facts, "inlink.md")))
-	assert.NotContains(t, read(), brainfstest.Sentinel, "static in-brain link")
-}
-
-func TestHydrateRefusesAnInBrainSymlinkAndDoesNotReturnItsTargetDuringASampledSwapRace(t *testing.T) {
-	brain, facts, _ := searchBrain(t)
-	target := inBrainTarget(t, brain)
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "..", "raw", "s.md"), filepath.Join(facts, "inlink.md")))
-	r, err := hydrate(brain, "wiki/w/facts/inlink.md")
-	assert.Error(t, err)
-	assert.NotContains(t, r.Excerpt+r.Title, brainfstest.Sentinel)
-
-	p := filepath.Join(facts, "r.md")
-	require.NoError(t, os.WriteFile(p, []byte("# r\n\nzqinside"), 0o644))
-	r, err = hydrate(brain, "wiki/w/facts/r.md")
-	require.NoError(t, err)
-	assert.Contains(t, r.Excerpt, "zqinside", "positive control: a regular note hydrates")
-	brainfstest.AssertNoLeakFrom(t, p, "# r\n\nzqinside", target, 1500*time.Millisecond, func() string {
-		r, _ := hydrate(brain, "wiki/w/facts/r.md")
-		return r.Title + r.Excerpt
-	})
-}

ingestion/internal/session/id_test.go

@@ -2,17 +2,14 @@ package session
 
 import (
 	"errors"
-	"fmt"
 	"os"
 	"path/filepath"
-	"sync/atomic"
 	"syscall"
 	"testing"
 	"time"
 
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
-	"golang.org/x/sys/unix"
 )
 
 // session_log passed the caller's session_id straight into
@@ -93,85 +90,3 @@ func TestAppendReturnsPromptlyOnAFIFOLogWithNoReader(t *testing.T) {
 		t.Fatal("Append blocked on a FIFO log with no reader")
 	}
 }
-
-// hyperguild#173: session_log followed a symlinked sessions dir.
-func TestAppendRefusesASymlinkedSessionsDir(t *testing.T) {
-	root := t.TempDir()
-	elsewhere := filepath.Join(root, "elsewhere")
-	require.NoError(t, os.MkdirAll(elsewhere, 0o755))
-	dir := filepath.Join(root, "sessions")
-	require.NoError(t, os.Symlink("elsewhere", dir))
-	assert.Error(t, Append(dir, "s", Entry{SessionID: "s"}))
-	ents, _ := os.ReadDir(elsewhere)
-	assert.Empty(t, ents, "a log was created through the symlinked dir")
-}
-
-// The sessions dir is swapped (RENAME_EXCHANGE) with a symlink to a
-// directory outside the brain while Append runs. Append opens through an
-// os.Root on the sessions dir's parent, so a swap can redirect it only
-// inside that parent (the #167 residual), never outside it.
-func TestAppendNeverCreatesALogOutsideTheParentUnderADirSwapRace(t *testing.T) {
-	brain := t.TempDir()
-	outside := t.TempDir()
-	dir := filepath.Join(brain, "sessions")
-	other := filepath.Join(brain, "sessions.link")
-	require.NoError(t, os.MkdirAll(dir, 0o755))
-	require.NoError(t, os.Symlink(outside, other))
-	var stop atomic.Bool
-	done := make(chan struct{})
-	go func() {
-		defer close(done)
-		for !stop.Load() {
-			_ = unix.Renameat2(unix.AT_FDCWD, dir, unix.AT_FDCWD, other, unix.RENAME_EXCHANGE)
-		}
-	}()
-	ok := 0
-	for i := 0; i < 20000; i++ {
-		if Append(dir, fmt.Sprintf("s%d", i), Entry{SessionID: "s"}) == nil {
-			ok++
-		}
-	}
-	stop.Store(true)
-	<-done
-	ents, _ := os.ReadDir(outside)
-	assert.Empty(t, ents, "logs were created outside the brain")
-	assert.Positive(t, ok, "positive control: appends to the real dir succeed")
-}
-
-// The log file is swapped between a regular file and a symlink to another
-// file in the brain while Append runs: Append writes only after confirming
-// the path is the regular file it opened, so the other file never grows.
-func TestAppendNeverWritesThroughALogSwappedForASymlink(t *testing.T) {
-	brain := t.TempDir()
-	dir := filepath.Join(brain, "sessions")
-	require.NoError(t, os.MkdirAll(dir, 0o755))
-	victim := filepath.Join(brain, "victim.md")
-	require.NoError(t, os.WriteFile(victim, []byte("untouched\n"), 0o644))
-	log := filepath.Join(dir, "s.jsonl")
-	var stop atomic.Bool
-	done := make(chan struct{})
-	go func() {
-		defer close(done)
-		tmp := log + ".swap"
-		for i := 0; !stop.Load(); i++ {
-			_ = os.Remove(tmp)
-			if i%2 == 0 {
-				_ = os.WriteFile(tmp, nil, 0o644)
-			} else {
-				_ = os.Symlink(filepath.Join("..", "victim.md"), tmp)
-			}
-			_ = os.Rename(tmp, log)
-		}
-	}()
-	ok := 0
-	for i := 0; i < 20000; i++ {
-		if Append(dir, "s", Entry{SessionID: "s"}) == nil {
-			ok++
-		}
-	}
-	stop.Store(true)
-	<-done
-	got, _ := os.ReadFile(victim)
-	assert.Equal(t, "untouched\n", string(got), "a log line was written through the swapped-in symlink")
-	assert.Positive(t, ok, "positive control: appends to the regular log succeed")
-}

ingestion/internal/session/session.go

@@ -65,42 +65,14 @@ func Append(sessionsDir, sessionID string, entry Entry) error {
 	if err := checkID(sessionID); err != nil {
 		return err
 	}
-	// Opened through an os.Root on the sessions dir's parent (the brain dir),
-	// so a sessions dir swapped for a symlink after the check below can
-	// redirect the log only inside that parent, never outside it (#173; the
-	// in-brain swap is the #167 residual).
-	parentDir, name := filepath.Dir(sessionsDir), filepath.Base(sessionsDir)
-	if err := os.MkdirAll(parentDir, 0o755); err != nil {
-		return fmt.Errorf("create sessions parent: %w", err)
-	}
-	root, err := os.OpenRoot(parentDir)
-	if err != nil {
-		return fmt.Errorf("open sessions parent: %w", err)
-	}
-	defer func() { _ = root.Close() }()
-	if err := root.Mkdir(name, 0o755); err != nil && !errors.Is(err, fs.ErrExist) {
+	if err := os.MkdirAll(sessionsDir, 0o755); err != nil {
 		return fmt.Errorf("create sessions dir: %w", err)
 	}
-	// The sessions dir itself must be a real directory, not a symlink that
-	// redirects the log elsewhere (hyperguild#173).
-	if fi, err := root.Lstat(name); err != nil {
-		return fmt.Errorf("stat sessions dir: %w", err)
-	} else if !fi.IsDir() {
-		return fmt.Errorf("sessions dir %s is not a real directory", sessionsDir)
-	}
-	logRel := name + "/" + sessionID + ".jsonl"
-	f, err := root.OpenFile(logRel, os.O_CREATE|os.O_APPEND|os.O_WRONLY|syscall.O_NOFOLLOW|syscall.O_NONBLOCK, 0o644)
+	path := filepath.Join(sessionsDir, sessionID+".jsonl")
+	f, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY|syscall.O_NOFOLLOW|syscall.O_NONBLOCK, 0o644)
 	if err != nil {
 		return fmt.Errorf("open session log: %w", err)
 	}
-	// os.Root follows an in-root final symlink even with O_NOFOLLOW, so
-	// confirm, before writing, that the path is the regular file we opened.
-	hfi, herr := f.Stat()
-	lfi, lerr := root.Lstat(logRel)
-	if herr != nil || lerr != nil || !lfi.Mode().IsRegular() || !os.SameFile(lfi, hfi) {
-		_ = f.Close()
-		return fmt.Errorf("session log %s is not a regular file", logRel)
-	}
 
 	line, err := json.Marshal(entry)
 	if err != nil {

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/vectorstore/sync_root_test.go

@@ -42,11 +42,6 @@ func TestSyncRefusesSymlinkedNotesAndSurvivesSwapRaces(t *testing.T) {
 	brain := t.TempDir()
 	writeNote(t, brain, "wiki/w/facts/ok.md", "inside note")
 	require.NoError(t, os.Symlink(brainfstest.Outside(t), filepath.Join(brain, "wiki", "w", "facts", "leak.md")))
-	// A link to a file elsewhere in the brain: os.Root allows it, only the
-	// regular-file checks refuse it (hyperguild#171). raw/ is not a scan root,
-	// so its sentinel can only arrive through the link.
-	inBrain := brainfstest.WriteSentinelAt(t, filepath.Join(brain, "raw", "s.md"))
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "..", "raw", "s.md"), filepath.Join(brain, "wiki", "w", "facts", "inlink.md")))
 
 	emb := &recordingEmbedder{}
 	store := &stubStore{}
@@ -56,7 +51,6 @@ func TestSyncRefusesSymlinkedNotesAndSurvivesSwapRaces(t *testing.T) {
 	assert.NotContains(t, emb.all(), brainfstest.Sentinel)
 	for p := range store.upserts {
 		assert.NotContains(t, p, "leak.md")
-		assert.NotContains(t, p, "inlink.md")
 	}
 
 	p := filepath.Join(brain, "knowledge", "r.md")
@@ -67,7 +61,6 @@ func TestSyncRefusesSymlinkedNotesAndSurvivesSwapRaces(t *testing.T) {
 		return e.all()
 	}
 	brainfstest.AssertNoLeak(t, p, "inside", 1500*time.Millisecond, sync)
-	brainfstest.AssertNoLeakFrom(t, p, "inside", inBrain, 1500*time.Millisecond, sync)
 	brainfstest.AssertNoHang(t, p, "inside", 1500*time.Millisecond, 6*time.Second, func() { _ = sync() })
 }