test(ingestion): /mcp's JWT validator and resource_metadata; narrow comments

PR #183 review (comment 15474):
- TestBuildMuxAnswers503ToAJWTOnMCPWhileTheIssuerIsUnresolved: building
  /mcp's middleware with a nil validator turns it red.
- TestBuildMuxMCP401CarriesResourceMetadataInWWWAuthenticate: building it
  with resourceMetadataURL "" turns it red.
- main.go, routes.go and the testMux comment now say exactly what is
  untested: main's restAuth fields and public map passed to buildMux, and
  ListenAndServe (hyperguild#182). Stale public-route list in the
  TestBuildMuxDoesNotWrapPublicRoutes comment corrected.

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

ingestion/internal/api/update.go

@@ -3,18 +3,15 @@ package api
 import (
 	"crypto/sha256"
 	"encoding/hex"
-	"errors"
 	"fmt"
-	"io/fs"
+	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs"
 	"os"
 	"path/filepath"
 	"strings"
 	"time"
 
 	"github.com/mathiasbq/hyperguild/ingestion/internal/brain"
-	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs"
 	"github.com/mathiasbq/hyperguild/ingestion/internal/claim"
-	"github.com/mathiasbq/hyperguild/ingestion/internal/notes"
 )
 
 // ContentHash returns the lowercase hex sha256 of b. It is the note's
@@ -94,23 +91,14 @@ func UpdateNote(brainDir string, opts UpdateNoteOptions) (relPath, contentHash,
 		rel = filepath.ToSlash(rel)
 	}
 
-	// The path is caller-supplied (brain_update): resolve it as brain_edit
-	// does, knowledge/ and wiki/ notes only, and read and rewrite it through
-	// the brain root, never through a symlink (hyperguild#169).
-	t, err := notes.Resolve(brainDir, rel, notes.ScopeNotes)
+	rel, abs, err := resolveWithin(brainDir, rel)
 	if err != nil {
 		return "", "", "", err
 	}
-	rel = t.Rel
-	bfs, err := brainfs.Open(brainDir)
-	if err != nil {
-		return "", "", "", fmt.Errorf("open brain: %w", err)
-	}
-	defer func() { _ = bfs.Close() }()
 
-	prior, err := bfs.ReadRegular(rel)
+	prior, err := os.ReadFile(abs)
 	if err != nil {
-		if errors.Is(err, fs.ErrNotExist) {
+		if os.IsNotExist(err) {
 			return "", "", "", fmt.Errorf("note %q does not exist: use brain_write to create", rel)
 		}
 		return "", "", "", fmt.Errorf("read target: %w", err)
@@ -176,7 +164,7 @@ func UpdateNote(brainDir string, opts UpdateNoteOptions) (relPath, contentHash,
 		return "", "", "", err
 	}
 	out := []byte(stamped)
-	if err := bfs.WriteRegular(rel, out); err != nil {
+	if err := os.WriteFile(abs, out, 0o644); err != nil {
 		return "", "", "", fmt.Errorf("write: %w", err)
 	}
 	return rel, ContentHash(out), priorHash, nil

ingestion/internal/api/update_scope_test.go

@@ -1,112 +0,0 @@
-package api_test
-
-import (
-	"os"
-	"path/filepath"
-	"sync"
-	"sync/atomic"
-	"testing"
-	"time"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-
-	"github.com/mathiasbq/hyperguild/ingestion/internal/api"
-)
-
-// brain_update passed the caller's path through resolveWithin, a lexical
-// containment check only: any file in the brain could be superseded
-// (classification.yaml, raw/, sessions/), and a final symlink was written
-// through. It now resolves like brain_edit: knowledge/ and wiki/ notes only,
-// read and rewritten through the brain root.
-func TestUpdateNoteRefusesPathsOutsideKnowledgeAndWikiNotes(t *testing.T) {
-	brain := t.TempDir()
-	files := map[string]string{
-		"classification.yaml": "levels: {}\n",
-		"raw/r.md":            "raw\n",
-		"sessions/s.jsonl":    "{}\n",
-		"wiki/w/facts/ok.md":  "---\ntitle: ok\n---\nold\n",
-		"knowledge/k.md":      "---\ntitle: k\n---\nold\n",
-		"wiki/w/facts/x.txt":  "txt\n",
-	}
-	for rel, body := range files {
-		p := filepath.Join(brain, filepath.FromSlash(rel))
-		require.NoError(t, os.MkdirAll(filepath.Dir(p), 0o755))
-		require.NoError(t, os.WriteFile(p, []byte(body), 0o644))
-	}
-	for _, rel := range []string{"classification.yaml", "raw/r.md", "sessions/s.jsonl", "wiki/w/facts/x.txt", "wiki/w/../../raw/r.md"} {
-		_, _, _, err := api.UpdateNote(brain, api.UpdateNoteOptions{Path: rel, Content: "replaced"})
-		assert.Error(t, err, rel)
-	}
-	for rel, body := range files {
-		if rel == "wiki/w/facts/ok.md" || rel == "knowledge/k.md" {
-			continue
-		}
-		got, err := os.ReadFile(filepath.Join(brain, filepath.FromSlash(rel)))
-		require.NoError(t, err)
-		assert.Equal(t, body, string(got), rel)
-	}
-	for _, rel := range []string{"wiki/w/facts/ok.md", "knowledge/k.md"} {
-		_, _, _, err := api.UpdateNote(brain, api.UpdateNoteOptions{Path: rel, Content: "new body"})
-		require.NoError(t, err, "positive control: %s", rel)
-		got, _ := os.ReadFile(filepath.Join(brain, filepath.FromSlash(rel)))
-		assert.Contains(t, string(got), "new body")
-	}
-}
-
-func TestUpdateNoteDoesNotWriteThroughASymlinkedNote(t *testing.T) {
-	brain := t.TempDir()
-	facts := filepath.Join(brain, "wiki", "w", "facts")
-	require.NoError(t, os.MkdirAll(facts, 0o755))
-	victim := filepath.Join(brain, "raw", "victim.md")
-	require.NoError(t, os.MkdirAll(filepath.Dir(victim), 0o755))
-	require.NoError(t, os.WriteFile(victim, []byte("untouched\n"), 0o644))
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "..", "raw", "victim.md"), filepath.Join(facts, "l.md")))
-	_, _, _, err := api.UpdateNote(brain, api.UpdateNoteOptions{Path: "wiki/w/facts/l.md", Content: "replaced"})
-	assert.Error(t, err)
-	got, _ := os.ReadFile(victim)
-	assert.Equal(t, "untouched\n", string(got))
-}
-
-// The note is swapped between a regular file and an in-brain symlink to a
-// raw/ file while UpdateNote runs: the read and the write each refuse a
-// symlink, so the raw/ file is never rewritten.
-func TestUpdateNoteNeverRewritesASymlinkSwappedInForTheNote(t *testing.T) {
-	brain := t.TempDir()
-	facts := filepath.Join(brain, "wiki", "w", "facts")
-	require.NoError(t, os.MkdirAll(facts, 0o755))
-	victim := filepath.Join(brain, "raw", "victim.md")
-	require.NoError(t, os.MkdirAll(filepath.Dir(victim), 0o755))
-	require.NoError(t, os.WriteFile(victim, []byte("untouched\n"), 0o644))
-	note := filepath.Join(facts, "n.md")
-	body := "---\ntitle: n\n---\nold\n"
-	require.NoError(t, os.WriteFile(note, []byte(body), 0o644))
-
-	var stop atomic.Bool
-	var wg sync.WaitGroup
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
-		tmp := note + ".swap"
-		for i := 0; !stop.Load(); i++ {
-			_ = os.Remove(tmp)
-			if i%2 == 0 {
-				_ = os.WriteFile(tmp, []byte(body), 0o644)
-			} else {
-				_ = os.Symlink(filepath.Join("..", "..", "..", "raw", "victim.md"), tmp)
-			}
-			_ = os.Rename(tmp, note)
-		}
-	}()
-	ok := 0
-	for deadline := time.Now().Add(1500 * time.Millisecond); time.Now().Before(deadline); {
-		if _, _, _, err := api.UpdateNote(brain, api.UpdateNoteOptions{Path: "wiki/w/facts/n.md", Content: "new"}); err == nil {
-			ok++
-		}
-	}
-	stop.Store(true)
-	wg.Wait()
-	got, _ := os.ReadFile(victim)
-	assert.Equal(t, "untouched\n", string(got))
-	assert.Positive(t, ok, "positive control: some updates reach the regular note")
-}

ingestion/internal/brain/tunnel.go

@@ -4,12 +4,9 @@ import (
 	"bufio"
 	"fmt"
 	"os"
-	"path"
 	"path/filepath"
 	"strings"
 	"time"
-
-	"github.com/mathiasbq/hyperguild/ingestion/internal/brainfs"
 )
 
 // seeAlsoHeader is the markdown heading used to group cross-wing links.
@@ -200,12 +197,6 @@ func fileExists(p string) bool {
 // section headers. Rejects same-wing pairs (a tunnel is by definition
 // cross-wing) and missing notes.
 func WriteTunnel(brainDir, sourcePath, targetPath string) error {
-	if err := checkNotePath(sourcePath); err != nil {
-		return fmt.Errorf("source: %w", err)
-	}
-	if err := checkNotePath(targetPath); err != nil {
-		return fmt.Errorf("target: %w", err)
-	}
 	srcWing, err := wingOf(sourcePath)
 	if err != nil {
 		return fmt.Errorf("source: %w", err)
@@ -218,50 +209,20 @@ func WriteTunnel(brainDir, sourcePath, targetPath string) error {
 		return fmt.Errorf("tunnel must cross wings; got both in %q", srcWing)
 	}
 
-	// Both notes are read and rewritten through the brain root, regular
-	// files only: brain_tunnel passes caller-supplied paths, and the brain is
-	// a Syncthing folder that can hold symlinks.
-	bfs, err := brainfs.Open(brainDir)
-	if err != nil {
-		return fmt.Errorf("open brain: %w", err)
-	}
-	defer func() { _ = bfs.Close() }()
-	srcContent, err := bfs.ReadRegular(sourcePath)
-	if err != nil {
+	srcFull := filepath.Join(brainDir, filepath.FromSlash(sourcePath))
+	tgtFull := filepath.Join(brainDir, filepath.FromSlash(targetPath))
+	if _, err := os.Stat(srcFull); err != nil {
 		return fmt.Errorf("source note: %w", err)
 	}
-	tgtContent, err := bfs.ReadRegular(targetPath)
-	if err != nil {
+	if _, err := os.Stat(tgtFull); err != nil {
 		return fmt.Errorf("target note: %w", err)
 	}
 
-	if out, changed, err := withSeeAlso(srcContent, wikilinkOf(targetPath)); err != nil {
+	if err := appendSeeAlso(srcFull, wikilinkOf(targetPath)); err != nil {
 		return fmt.Errorf("update source: %w", err)
-	} else if changed {
-		if err := bfs.WriteRegular(sourcePath, out); err != nil {
-			return fmt.Errorf("update source: %w", err)
-		}
 	}
-	if out, changed, err := withSeeAlso(tgtContent, wikilinkOf(sourcePath)); err != nil {
+	if err := appendSeeAlso(tgtFull, wikilinkOf(sourcePath)); err != nil {
 		return fmt.Errorf("update target: %w", err)
-	} else if changed {
-		if err := bfs.WriteRegular(targetPath, out); err != nil {
-			return fmt.Errorf("update target: %w", err)
-		}
-	}
-	return nil
-}
-
-// checkNotePath accepts only a clean, local wiki/<wing>/<hall>/.../<slug>.md
-// path: no "." or ".." segments, no empty segments, no leading slash.
-func checkNotePath(p string) error {
-	if p == "" || path.Clean(p) != p || !filepath.IsLocal(p) || !strings.HasSuffix(p, ".md") {
-		return fmt.Errorf("not a clean wiki note path: %q", p)
-	}
-	for _, part := range strings.Split(p, "/") {
-		if part == "" || part == "." || part == ".." {
-			return fmt.Errorf("not a clean wiki note path: %q", p)
-		}
 	}
 	return nil
 }
@@ -287,13 +248,16 @@ func wingOf(relPath string) (string, error) {
 	return parts[1], nil
 }
 
-// withSeeAlso returns content with `- [[link]]` under its See also section,
-// creating the section if absent. changed is false when the link is already
-// present.
-func withSeeAlso(content []byte, link string) (out []byte, changed bool, err error) {
+// appendSeeAlso inserts `- [[link]]` under the file's See also section,
+// creating the section if absent. No-op when the link is already present.
+func appendSeeAlso(filePath, link string) error {
+	content, err := os.ReadFile(filePath)
+	if err != nil {
+		return err
+	}
 	wikilink := "[[" + link + "]]"
 	if strings.Contains(string(content), wikilink) {
-		return content, false, nil
+		return nil
 	}
 
 	bullet := "- " + wikilink
@@ -302,7 +266,8 @@ func withSeeAlso(content []byte, link string) (out []byte, changed bool, err err
 		// No section yet — append a fresh one. Always emit a trailing
 		// newline so subsequent appends don't merge into the previous line.
 		trimmed := strings.TrimRight(string(content), "\n")
-		return []byte(trimmed + "\n\n" + seeAlsoHeader + "\n\n" + bullet + "\n"), true, nil
+		out := trimmed + "\n\n" + seeAlsoHeader + "\n\n" + bullet + "\n"
+		return os.WriteFile(filePath, []byte(out), 0o644)
 	}
 
 	// Section exists — splice the bullet in just before the next `## `
@@ -328,11 +293,12 @@ func withSeeAlso(content []byte, link string) (out []byte, changed bool, err err
 		b.WriteByte('\n')
 	}
 	if err := scanner.Err(); err != nil {
-		return nil, false, err
+		return err
 	}
 	if !inserted {
 		// section was the last thing in the file — just append bullet
-		return []byte(strings.TrimRight(b.String(), "\n") + "\n" + bullet + "\n"), true, nil
+		out := strings.TrimRight(b.String(), "\n") + "\n" + bullet + "\n"
+		return os.WriteFile(filePath, []byte(out), 0o644)
 	}
-	return []byte(b.String()), true, nil
+	return os.WriteFile(filePath, []byte(b.String()), 0o644)
 }

ingestion/internal/brain/tunnel_root_test.go

@@ -1,141 +0,0 @@
-package brain_test
-
-import (
-	"os"
-	"path/filepath"
-	"strings"
-	"sync"
-	"sync/atomic"
-	"testing"
-	"time"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-
-	"github.com/mathiasbq/hyperguild/ingestion/internal/brain"
-)
-
-// brain_tunnel passes caller-supplied source and target paths to WriteTunnel,
-// which checked only "wiki/<wing>/..." and then joined them onto the brain
-// dir: ".." segments resolved outside the brain and appendSeeAlso rewrote the
-// file there.
-func TestWriteTunnelRefusesATargetThatTraversesOutOfTheBrain(t *testing.T) {
-	brain0 := t.TempDir()
-	src := filepath.Join(brain0, "wiki", "a", "facts", "s.md")
-	require.NoError(t, os.MkdirAll(filepath.Dir(src), 0o755))
-	require.NoError(t, os.WriteFile(src, []byte("---\ntitle: S\n---\nbody\n"), 0o644))
-	victim := filepath.Join(t.TempDir(), "victim.md")
-	require.NoError(t, os.WriteFile(victim, []byte("untouched\n"), 0o644))
-
-	up := strings.Repeat("../", strings.Count(filepath.Clean(brain0), "/")+3)
-	target := "wiki/b/x/" + up + strings.TrimPrefix(victim, "/")
-	err := brain.WriteTunnel(brain0, "wiki/a/facts/s.md", target)
-	assert.Error(t, err)
-	got, rerr := os.ReadFile(victim)
-	require.NoError(t, rerr)
-	assert.Equal(t, "untouched\n", string(got), "a file outside the brain was modified")
-}
-
-func TestWriteTunnelRefusesUncleanOrNonWikiPaths(t *testing.T) {
-	brain0 := t.TempDir()
-	for _, p := range []string{"wiki/a/facts/s.md", "wiki/b/facts/t.md", "wiki/b/facts/t.txt", "raw/r.md"} {
-		require.NoError(t, os.MkdirAll(filepath.Dir(filepath.Join(brain0, p)), 0o755))
-		require.NoError(t, os.WriteFile(filepath.Join(brain0, p), []byte("x\n"), 0o644))
-	}
-	for _, target := range []string{
-		"wiki/b/facts/../../../raw/r.md",
-		"wiki/b/./facts/t.md",
-		"wiki/b//facts/t.md",
-		"/wiki/b/facts/t.md",
-		"wiki/b/facts/t.txt",
-		"wiki/b/facts/",
-	} {
-		assert.Error(t, brain.WriteTunnel(brain0, "wiki/a/facts/s.md", target), target)
-	}
-	for _, p := range []string{"raw/r.md", "wiki/b/facts/t.txt"} {
-		got, err := os.ReadFile(filepath.Join(brain0, p))
-		require.NoError(t, err)
-		assert.Equal(t, "x\n", string(got), p)
-	}
-	require.NoError(t, brain.WriteTunnel(brain0, "wiki/a/facts/s.md", "wiki/b/facts/t.md"), "positive control")
-	got, err := os.ReadFile(filepath.Join(brain0, "wiki", "b", "facts", "t.md"))
-	require.NoError(t, err)
-	assert.Contains(t, string(got), "[[a/facts/s]]")
-}
-
-func TestWriteTunnelDoesNotWriteThroughASymlinkedNote(t *testing.T) {
-	brain0 := t.TempDir()
-	src := filepath.Join(brain0, "wiki", "a", "facts", "s.md")
-	require.NoError(t, os.MkdirAll(filepath.Dir(src), 0o755))
-	require.NoError(t, os.WriteFile(src, []byte("x\n"), 0o644))
-	tdir := filepath.Join(brain0, "wiki", "b", "facts")
-	require.NoError(t, os.MkdirAll(tdir, 0o755))
-	victim := filepath.Join(t.TempDir(), "victim.md")
-	require.NoError(t, os.WriteFile(victim, []byte("untouched\n"), 0o644))
-	require.NoError(t, os.Symlink(victim, filepath.Join(tdir, "t.md")))
-	assert.Error(t, brain.WriteTunnel(brain0, "wiki/a/facts/s.md", "wiki/b/facts/t.md"))
-	got, err := os.ReadFile(victim)
-	require.NoError(t, err)
-	assert.Equal(t, "untouched\n", string(got))
-
-	// The same with a link to a file elsewhere in the brain, which os.Root
-	// would follow.
-	inVictim := filepath.Join(brain0, "raw", "v.md")
-	require.NoError(t, os.MkdirAll(filepath.Dir(inVictim), 0o755))
-	require.NoError(t, os.WriteFile(inVictim, []byte("untouched\n"), 0o644))
-	require.NoError(t, os.Symlink(filepath.Join("..", "..", "..", "raw", "v.md"), filepath.Join(tdir, "u.md")))
-	assert.Error(t, brain.WriteTunnel(brain0, "wiki/a/facts/s.md", "wiki/b/facts/u.md"))
-	got, err = os.ReadFile(inVictim)
-	require.NoError(t, err)
-	assert.Equal(t, "untouched\n", string(got))
-	got, err = os.ReadFile(src)
-	require.NoError(t, err)
-	assert.Equal(t, "x\n", string(got), "the source is not touched when the target is refused")
-}
-
-// The target is swapped between a regular note and a symlink to an in-brain
-// file outside wiki/ while WriteTunnel runs: the read and the write each
-// refuse a symlink, so the other file is never rewritten.
-func TestWriteTunnelNeverRewritesASymlinkSwappedInForTheTarget(t *testing.T) {
-	brain0 := t.TempDir()
-	src := filepath.Join(brain0, "wiki", "a", "facts", "s.md")
-	require.NoError(t, os.MkdirAll(filepath.Dir(src), 0o755))
-	require.NoError(t, os.WriteFile(src, []byte("x\n"), 0o644))
-	tdir := filepath.Join(brain0, "wiki", "b", "facts")
-	require.NoError(t, os.MkdirAll(tdir, 0o755))
-	victim := filepath.Join(brain0, "raw", "victim.md")
-	require.NoError(t, os.MkdirAll(filepath.Dir(victim), 0o755))
-	require.NoError(t, os.WriteFile(victim, []byte("untouched\n"), 0o644))
-	tgt := filepath.Join(tdir, "t.md")
-	require.NoError(t, os.WriteFile(tgt, []byte("t\n"), 0o644))
-
-	var stop atomic.Bool
-	var wg sync.WaitGroup
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
-		tmp := tgt + ".swap"
-		for i := 0; !stop.Load(); i++ {
-			_ = os.Remove(tmp)
-			if i%2 == 0 {
-				_ = os.WriteFile(tmp, []byte("t\n"), 0o644)
-			} else {
-				_ = os.Symlink(filepath.Join("..", "..", "..", "raw", "victim.md"), tmp)
-			}
-			_ = os.Rename(tmp, tgt)
-		}
-	}()
-	ok := 0
-	for deadline := time.Now().Add(1500 * time.Millisecond); time.Now().Before(deadline); {
-		if brain.WriteTunnel(brain0, "wiki/a/facts/s.md", "wiki/b/facts/t.md") == nil {
-			ok++
-		}
-		_ = os.WriteFile(src, []byte("x\n"), 0o644)
-	}
-	stop.Store(true)
-	wg.Wait()
-	got, err := os.ReadFile(victim)
-	require.NoError(t, err)
-	assert.Equal(t, "untouched\n", string(got), "the swapped-in symlink's target was rewritten")
-	assert.Positive(t, ok, "positive control: some tunnels were written to the regular target")
-}

ingestion/internal/brainfs/brainfs.go

@@ -249,41 +249,3 @@ func (b *Brain) WalkRegular(relDir string, fn func(rel string) error, onErr func
 		return fn(p)
 	})
 }
-
-// WriteRegular replaces the contents of an existing regular file at a
-// brain-relative path. It never creates a file and never writes through a
-// final symlink: os.Root.OpenFile follows an in-root final symlink even with
-// 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. 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 {
-	rel = filepath.ToSlash(rel)
-	lfi, err := b.root.Lstat(rel)
-	if err != nil {
-		return err
-	}
-	if !lfi.Mode().IsRegular() {
-		return fmt.Errorf("%s: %w", rel, ErrNotRegular)
-	}
-	f, err := b.root.OpenFile(rel, os.O_WRONLY|syscall.O_NOFOLLOW|syscall.O_NONBLOCK, 0)
-	if err != nil {
-		return err
-	}
-	defer func() { _ = f.Close() }()
-	fi, err := f.Stat()
-	if err != nil {
-		return err
-	}
-	if !fi.Mode().IsRegular() || !os.SameFile(lfi, fi) {
-		return fmt.Errorf("%s: changed while opening: %w", rel, ErrNotRegular)
-	}
-	if err := f.Truncate(0); err != nil {
-		return err
-	}
-	if _, err := f.Write(data); err != nil {
-		return err
-	}
-	return f.Close()
-}

ingestion/internal/brainfs/brainfs_test.go

@@ -263,52 +263,6 @@ func TestReadRegularNeverReturnsAnInBrainFileSwappedInBehindASymlink(t *testing.
 	assert.Positive(t, ok, "positive control: the regular file is read")
 }
 
-func TestWriteRegularRefusesFinalSymlinksFIFOsEscapesAndMissingFilesAndRewritesRegularFiles(t *testing.T) {
-	dir := t.TempDir()
-	outside := filepath.Join(t.TempDir(), "o.md")
-	require.NoError(t, os.WriteFile(outside, []byte("untouched"), 0o644))
-	require.NoError(t, os.Symlink(outside, filepath.Join(dir, "l.md")))
-	require.NoError(t, syscall.Mkfifo(filepath.Join(dir, "f.md"), 0o644))
-	require.NoError(t, os.WriteFile(filepath.Join(dir, "n.md"), []byte("old content"), 0o644))
-	b, err := Open(dir)
-	require.NoError(t, err)
-	defer func() { _ = b.Close() }()
-
-	assert.Error(t, b.WriteRegular("l.md", []byte("x")))
-	got, _ := os.ReadFile(outside)
-	assert.Equal(t, "untouched", string(got))
-
-	// A symlink to another file inside the brain: os.Root would allow it,
-	// only O_NOFOLLOW refuses it.
-	require.NoError(t, os.WriteFile(filepath.Join(dir, "in.md"), []byte("inside"), 0o644))
-	require.NoError(t, os.Symlink("in.md", filepath.Join(dir, "il.md")))
-	assert.Error(t, b.WriteRegular("il.md", []byte("x")))
-	got, _ = os.ReadFile(filepath.Join(dir, "in.md"))
-	assert.Equal(t, "inside", string(got))
-
-	// A reader held open, so a non-blocking write open would succeed. The
-	// Lstat type check refuses the FIFO first; the handle check and
-	// O_NONBLOCK matter only if it is swapped in after the Lstat.
-	r, err := os.OpenFile(filepath.Join(dir, "f.md"), os.O_RDONLY|syscall.O_NONBLOCK, 0)
-	require.NoError(t, err)
-	defer func() { _ = r.Close() }()
-	done := make(chan error, 1)
-	go func() { done <- b.WriteRegular("f.md", []byte("x")) }()
-	select {
-	case err := <-done:
-		assert.Error(t, err)
-	case <-time.After(3 * time.Second):
-		t.Fatal("WriteRegular hung on a FIFO")
-	}
-
-	assert.Error(t, b.WriteRegular("../"+filepath.Base(filepath.Dir(outside))+"/o.md", []byte("x")))
-	assert.Error(t, b.WriteRegular("missing.md", []byte("x")), "does not create files")
-
-	require.NoError(t, b.WriteRegular("n.md", []byte("new")))
-	got, _ = os.ReadFile(filepath.Join(dir, "n.md"))
-	assert.Equal(t, "new", string(got), "truncated and rewritten")
-}
-
 func TestReadDirDirsListsOnlyRealSubdirsAndRefusesSymlinkedComponents(t *testing.T) {
 	dir := t.TempDir()
 	require.NoError(t, os.MkdirAll(filepath.Join(dir, "a", "real"), 0o755))

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/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/session/id_test.go

@@ -1,92 +0,0 @@
-package session
-
-import (
-	"errors"
-	"os"
-	"path/filepath"
-	"syscall"
-	"testing"
-	"time"
-
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
-)
-
-// session_log passed the caller's session_id straight into
-// filepath.Join(sessionsDir, id+".jsonl") and opened it O_CREATE|O_APPEND:
-// path segments in the id created or appended files anywhere the pod could
-// write. The id is now a plain name, and the open does not follow a final
-// symlink.
-func TestAppendRefusesSessionIDsThatAreNotPlainNames(t *testing.T) {
-	root := t.TempDir()
-	dir := filepath.Join(root, "sessions")
-	for _, id := range []string{"../x", "a/b", "/abs", ".", "..", ".hidden", "", "a\\b", "a\x00b"} {
-		assert.Error(t, Append(dir, id, Entry{SessionID: id}), "%q", id)
-	}
-	ents, _ := os.ReadDir(root)
-	for _, e := range ents {
-		assert.Equal(t, "sessions", e.Name(), "nothing created beside the sessions dir")
-	}
-	for _, id := range []string{"1557b2e1-bf0d-5c4f-bbe3-0754d087e356", "_routing", "2026-05-05-infra.plan", "0"} {
-		require.NoError(t, Append(dir, id, Entry{SessionID: id}), "positive control: %q", id)
-	}
-}
-
-func TestAppendDoesNotWriteThroughASymlinkedLog(t *testing.T) {
-	root := t.TempDir()
-	dir := filepath.Join(root, "sessions")
-	require.NoError(t, os.MkdirAll(dir, 0o755))
-	victim := filepath.Join(root, "victim.md")
-	require.NoError(t, os.WriteFile(victim, []byte("untouched\n"), 0o644))
-	require.NoError(t, os.Symlink(filepath.Join("..", "victim.md"), filepath.Join(dir, "s.jsonl")))
-	assert.Error(t, Append(dir, "s", Entry{SessionID: "s"}))
-	got, _ := os.ReadFile(victim)
-	assert.Equal(t, "untouched\n", string(got))
-}
-
-func TestReadRefusesSessionIDsThatAreNotPlainNames(t *testing.T) {
-	root := t.TempDir()
-	require.NoError(t, os.WriteFile(filepath.Join(root, "x.jsonl"), []byte(`{"session_id":"x"}`+"\n"), 0o644))
-	_, err := Read(filepath.Join(root, "sessions"), "../x")
-	assert.Error(t, err)
-}
-
-// A name that starts plainly and then climbs out with ".." is exactly what the
-// ban on "/" in the id's tail stops: filepath.Join cleans "a/../../x" to a
-// path beside the sessions dir without needing sessions/a to exist. The
-// assertion is on the refusal itself (ErrInvalidID), not on any error.
-func TestAppendRefusesAnIDThatClimbsOutAfterAPlainPrefix(t *testing.T) {
-	root := t.TempDir()
-	dir := filepath.Join(root, "sessions")
-	require.NoError(t, os.MkdirAll(dir, 0o755))
-	for _, id := range []string{"a/../../escape", "a/../../../escape", "a/../b"} {
-		err := Append(dir, id, Entry{SessionID: id})
-		assert.ErrorIs(t, err, ErrInvalidID, "%q", id)
-	}
-	_, err := os.Lstat(filepath.Join(root, "escape.jsonl"))
-	assert.True(t, errors.Is(err, os.ErrNotExist), "nothing created beside the sessions dir")
-	_, err = os.Lstat(filepath.Join(dir, "b.jsonl"))
-	assert.True(t, errors.Is(err, os.ErrNotExist), "no in-dir alias created either")
-}
-
-// Append does no Lstat type check, so O_NONBLOCK is the only thing that keeps
-// a FIFO named <id>.jsonl with no reader from blocking session_log forever.
-func TestAppendReturnsPromptlyOnAFIFOLogWithNoReader(t *testing.T) {
-	dir := filepath.Join(t.TempDir(), "sessions")
-	require.NoError(t, os.MkdirAll(dir, 0o755))
-	fifo := filepath.Join(dir, "s.jsonl")
-	require.NoError(t, syscall.Mkfifo(fifo, 0o644))
-	done := make(chan error, 1)
-	go func() { done <- Append(dir, "s", Entry{SessionID: "s"}) }()
-	select {
-	case err := <-done:
-		assert.Error(t, err, "a FIFO with no reader is refused, not written")
-	case <-time.After(3 * time.Second):
-		// Unblock the stuck open so the goroutine and TempDir cleanup finish.
-		if r, err := os.OpenFile(fifo, os.O_RDONLY|syscall.O_NONBLOCK, 0); err == nil {
-			defer r.Close() //nolint:errcheck
-		}
-		<-done
-		t.Fatal("Append blocked on a FIFO log with no reader")
-	}
-}

ingestion/internal/session/session.go

@@ -9,8 +9,6 @@ import (
 	"io/fs"
 	"os"
 	"path/filepath"
-	"regexp"
-	"syscall"
 	"time"
 )
 
@@ -44,32 +42,13 @@ type Attempt struct {
 	RunnerOutput  string `json:"runner_output,omitempty"`
 }
 
-// idPattern is a plain file name: session_log takes the id from the caller,
-// and a path segment in it created or appended files anywhere the pod could
-// write (hyperguild#169).
-var idPattern = regexp.MustCompile(`^[A-Za-z0-9_][A-Za-z0-9._-]{0,127}$`)
-
-// ErrInvalidID is returned when a session id is not a plain file name.
-var ErrInvalidID = errors.New("session id is not a plain name")
-
-func checkID(sessionID string) error {
-	if !idPattern.MatchString(sessionID) {
-		return fmt.Errorf("%w: %q", ErrInvalidID, sessionID)
-	}
-	return nil
-}
-
 // Append writes entry as a single JSON line to sessionsDir/{sessionID}.jsonl.
-// The open does not follow a final symlink.
 func Append(sessionsDir, sessionID string, entry Entry) error {
-	if err := checkID(sessionID); err != nil {
-		return err
-	}
 	if err := os.MkdirAll(sessionsDir, 0o755); err != nil {
 		return fmt.Errorf("create sessions dir: %w", err)
 	}
 	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)
+	f, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0o644)
 	if err != nil {
 		return fmt.Errorf("open session log: %w", err)
 	}
@@ -91,9 +70,6 @@ func Append(sessionsDir, sessionID string, entry Entry) error {
 
 // Read returns all entries for sessionID. Returns empty slice if no log exists.
 func Read(sessionsDir, sessionID string) ([]Entry, error) {
-	if err := checkID(sessionID); err != nil {
-		return nil, err
-	}
 	path := filepath.Join(sessionsDir, sessionID+".jsonl")
 	f, err := os.Open(path)
 	if errors.Is(err, fs.ErrNotExist) {

ingestion/internal/symlinkguard/symlinkguard.go

@@ -18,14 +18,9 @@ import (
 	"sort"
 	"strconv"
 	"strings"
-	"sync"
-	"sync/atomic"
 	"time"
 )
 
-// shutdownFlushTimeout bounds the final flush when Watch stops.
-var shutdownFlushTimeout = 5 * time.Second
-
 // DefaultInterval is used when Watch is given a non-positive interval.
 const DefaultInterval = 30 * time.Second
 
@@ -138,32 +133,13 @@ func Scan(brainDir string) (Result, error) {
 // queue until Notify succeeds (see alertQueue): an outage delays them, and
 // any that do not fit the bounded queue, or are undeliverable, are counted in
 // a summary that is never dropped, so every incident is delivered or counted.
-//
-// Delivery runs in its own goroutine (hyperguild#164): a hung notifier, with
-// a full queue, blocked one flush for several notify timeouts, and while the
-// scan waited on it a planted link stayed readable for several intervals.
-// The scan hands alerts over without blocking; any that do not fit are
-// counted in the summary. When ctx ends, Watch returns after a final flush
-// of what was handed over (bounded by shutdownFlushTimeout); alerts that
-// flush cannot deliver are counted in one error log line instead. That
-// shutdown path only runs for a caller that cancels ctx: cmd/server passes
-// context.Background(), so in production the flush on handoff is what keeps
-// alerts from waiting on a restart.
 func Watch(ctx context.Context, brainDir string, interval time.Duration, n Notifier) {
 	if interval <= 0 {
 		interval = DefaultInterval
 	}
 	t := time.NewTicker(interval)
 	defer t.Stop()
-	alerts := make(chan string, maxPending)
-	var overflow atomic.Int64
-	var wg sync.WaitGroup
-	wg.Add(1)
-	go func() { defer wg.Done(); deliver(ctx, interval, n, alerts, &overflow) }()
-	// The scan is the only sender: closing alerts tells deliver to drain and
-	// flush once more, and Watch returns only after it has.
-	defer func() { close(alerts); wg.Wait() }()
-	q := alertSender{alerts: alerts, overflow: &overflow}
+	q := &alertQueue{}
 	reported := ""
 	for {
 		select {
@@ -192,76 +168,7 @@ func Watch(ctx context.Context, brainDir string, interval time.Duration, n Notif
 					". Readers may follow symlinks out of the brain; fix them.")
 			}
 		}
-	}
-}
-
-// alertSender hands alerts to deliver without ever blocking the scan; an
-// alert that does not fit is counted in overflow, which deliver adds to the
-// summary.
-type alertSender struct {
-	alerts   chan<- string
-	overflow *atomic.Int64
-}
-
-func (s alertSender) push(msg string) {
-	select {
-	case s.alerts <- msg:
-	default:
-		s.overflow.Add(1)
-	}
-}
-
-// deliver owns the alertQueue. It flushes as soon as an alert is handed
-// over, and again every interval while any are pending (outage retries).
-// When alerts is closed (Watch is stopping) it drains it and flushes once
-// more, bounded by shutdownFlushTimeout, so an alert handed over just before
-// shutdown is not lost (PR #180 review). Whatever that flush cannot deliver
-// is logged as one error with its counts, never dropped silently.
-func deliver(ctx context.Context, interval time.Duration, n Notifier, alerts <-chan string, overflow *atomic.Int64) {
-	t := time.NewTicker(interval)
-	defer t.Stop()
-	q := &alertQueue{}
-	// drain moves everything handed over into the queue; it reports false
-	// once alerts is closed.
-	drain := func() bool {
-		defer func() { q.suppressed += int(overflow.Swap(0)) }()
-		for {
-			select {
-			case msg, ok := <-alerts:
-				if !ok {
-					return false
-				}
-				q.push(msg)
-			default:
-				return true
-			}
-		}
-	}
-	for {
-		select {
-		case msg, ok := <-alerts:
-			if ok {
-				q.push(msg)
-				ok = drain()
-			}
-			if !ok {
-				q.suppressed += int(overflow.Swap(0))
-				fctx, cancel := context.WithTimeout(context.WithoutCancel(ctx), shutdownFlushTimeout)
-				q.flush(fctx, n)
-				cancel()
-				if len(q.items) > 0 || q.suppressed > 0 {
-					slog.Error("symlink tripwire alerts not delivered at shutdown",
-						"undelivered", len(q.items), "suppressed", q.suppressed)
-				}
-				return
-			}
-			q.flush(ctx, n)
-		case <-t.C:
-			if !drain() {
-				continue // the closed channel is handled by the case above
-			}
-			q.flush(ctx, n)
-		}
+		q.flush(ctx, n)
 	}
 }
 

ingestion/internal/symlinkguard/symlinkguard_test.go

@@ -1,12 +1,10 @@
 package symlinkguard
 
 import (
-	"bytes"
 	"context"
 	"errors"
 	"fmt"
 	"os"
-	"log/slog"
 	"path/filepath"
 	"strconv"
 	"strings"
@@ -347,19 +345,13 @@ func TestWatchDropsAMessageThatNeverSendsSoLaterAlertsFlow(t *testing.T) {
 	}, 3*time.Second, 10*time.Millisecond, "a later alert is delivered despite a poison message")
 }
 
-// toggleNotifier fails while down is set. Like the real audit.NtfyNotifier
-// (http.NewRequestWithContext), it also fails, without recording, when its
-// ctx is already done (PR #180 round 2: notifiers that ignored ctx let a
-// final flush on the cancelled ctx pass).
+// toggleNotifier fails while down is set.
 type toggleNotifier struct {
 	recNotifier
 	down atomic.Bool
 }
 
 func (r *toggleNotifier) Notify(ctx context.Context, m string) error {
-	if err := ctx.Err(); err != nil {
-		return err
-	}
 	if r.down.Load() {
 		return errors.New("ntfy down")
 	}
@@ -504,271 +496,3 @@ func TestWatchDropsAPoisonMessageAndCountsIt(t *testing.T) {
 		return false
 	}, 3*time.Second, 5*time.Millisecond, "the dropped poison alert is counted in a summary")
 }
-
-// hungNotifier answers every Notify only after latency (or when ctx ends),
-// with an outage error: an ntfy that accepts connections but never responds
-// until its timeout.
-type hungNotifier struct{ latency time.Duration }
-
-func (h hungNotifier) Notify(ctx context.Context, _ string) error {
-	select {
-	case <-time.After(h.latency):
-	case <-ctx.Done():
-	}
-	return errors.New("ntfy timeout")
-}
-
-func waitGone(t *testing.T, link string) {
-	t.Helper()
-	require.Eventually(t, func() bool { _, err := os.Lstat(link); return os.IsNotExist(err) }, 10*time.Second, time.Millisecond)
-}
-
-// hyperguild#164: alerts were flushed in the scan goroutine, so with a hung
-// ntfy and a full queue one flush (6 x notify timeout) delayed the next scan.
-// The notifier here is slower than the interval, as in production (10 s
-// timeout vs 30 s interval with 6 messages), so the alert handoff is full:
-// a scan that waited on it would keep a link for seconds.
-func TestWatchLinkLifetimeStaysNearOneIntervalWithANotifierSlowerThanTheInterval(t *testing.T) {
-	const interval = 100 * time.Millisecond
-	brain := t.TempDir()
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-	go Watch(ctx, brain, interval, hungNotifier{latency: 400 * time.Millisecond})
-
-	for i := 0; i < 2*maxPending+3; i++ { // overfill queue and handoff
-		link := filepath.Join(brain, "fill"+strconv.Itoa(i))
-		require.NoError(t, os.Symlink(t.TempDir(), link))
-		waitGone(t, link)
-	}
-	var worst time.Duration
-	for i := 0; i < 6; i++ {
-		link := filepath.Join(brain, "probe"+strconv.Itoa(i))
-		require.NoError(t, os.Symlink(t.TempDir(), link))
-		planted := time.Now()
-		waitGone(t, link)
-		worst = max(worst, time.Since(planted))
-	}
-	assert.LessOrEqual(t, worst, interval+interval/2, "worst link lifetime %v with a hung notifier", worst)
-}
-
-// Review of PR #180: delivery waited for its own tick, about one interval
-// after the removal. An alert is now flushed as soon as it is handed over.
-func TestWatchDeliversARemovalAlertWellWithinOneInterval(t *testing.T) {
-	const interval = 400 * time.Millisecond
-	brain := t.TempDir()
-	n := &recNotifier{}
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-	go Watch(ctx, brain, interval, n)
-	link := filepath.Join(brain, "prompt")
-	require.NoError(t, os.Symlink(t.TempDir(), link))
-	waitGone(t, link)
-	removed := time.Now()
-	require.Eventually(t, func() bool { return n.count() == 1 }, 2*time.Second, time.Millisecond)
-	assert.Less(t, time.Since(removed), interval/4)
-}
-
-// Review of PR #180: on ctx end, deliver returned without draining what the
-// scan had handed over, so a removal just before shutdown was neither
-// delivered nor counted. Watch now drains and flushes before returning.
-func TestWatchDeliversAnAlertHandedOverJustBeforeShutdown(t *testing.T) {
-	for i := 0; i < 20; i++ {
-		brain := t.TempDir()
-		n := &recNotifier{}
-		ctx, cancel := context.WithCancel(context.Background())
-		done := make(chan struct{})
-		go func() { Watch(ctx, brain, 5*time.Millisecond, n); close(done) }()
-		link := filepath.Join(brain, "late")
-		require.NoError(t, os.Symlink(t.TempDir(), link))
-		waitGone(t, link)
-		cancel()
-		<-done
-		require.Equal(t, 1, n.count(), "iteration %d: the removal alert was lost at shutdown", i)
-	}
-}
-
-// blockingNotifier holds every Notify until its ctx ends, tracking calls in
-// flight.
-type blockingNotifier struct{ inFlight atomic.Int32 }
-
-func (b *blockingNotifier) Notify(ctx context.Context, _ string) error {
-	b.inFlight.Add(1)
-	defer b.inFlight.Add(-1)
-	<-ctx.Done()
-	return ctx.Err()
-}
-
-// Watch does not return while its delivery goroutine is still notifying.
-func TestWatchReturnsOnlyAfterDeliveryHasStopped(t *testing.T) {
-	prev := shutdownFlushTimeout
-	shutdownFlushTimeout = 50 * time.Millisecond
-	t.Cleanup(func() { shutdownFlushTimeout = prev })
-	brain := t.TempDir()
-	n := &blockingNotifier{}
-	ctx, cancel := context.WithCancel(context.Background())
-	done := make(chan struct{})
-	go func() { Watch(ctx, brain, 5*time.Millisecond, n); close(done) }()
-	link := filepath.Join(brain, "x")
-	require.NoError(t, os.Symlink(t.TempDir(), link))
-	waitGone(t, link)
-	require.Eventually(t, func() bool { return n.inFlight.Load() == 1 }, 2*time.Second, time.Millisecond)
-	cancel()
-	select {
-	case <-done:
-	case <-time.After(5 * time.Second):
-		t.Fatal("Watch did not return after cancel")
-	}
-	assert.Zero(t, n.inFlight.Load(), "Notify still running after Watch returned")
-}
-
-// slowToggleNotifier fails slowly (a hung ntfy) while down, then records.
-type slowToggleNotifier struct {
-	recNotifier
-	down    atomic.Bool
-	latency time.Duration
-}
-
-func (r *slowToggleNotifier) Notify(ctx context.Context, m string) error {
-	if r.down.Load() {
-		select {
-		case <-time.After(r.latency):
-		case <-ctx.Done():
-		}
-		return errors.New("ntfy timeout")
-	}
-	return r.recNotifier.Notify(ctx, m)
-}
-
-// Review of PR #180: with a slow notifier the scan's handoff overflows, and
-// those alerts exist only in the overflow counter. Every removal is still
-// delivered or counted in the summary.
-func TestWatchCountsHandoffOverflowWithASlowNotifier(t *testing.T) {
-	brain := t.TempDir()
-	n := &slowToggleNotifier{latency: 30 * time.Millisecond}
-	n.down.Store(true)
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
-	go Watch(ctx, brain, 2*time.Millisecond, n)
-	const plants = 40
-	for i := 0; i < plants; i++ {
-		link := filepath.Join(brain, "ov"+strconv.Itoa(i))
-		require.NoError(t, os.Symlink(t.TempDir(), link))
-		waitGone(t, link)
-	}
-	n.down.Store(false)
-	delivered, counted := 0, 0
-	require.Eventually(t, func() bool {
-		n.mu.Lock()
-		defer n.mu.Unlock()
-		delivered, counted = 0, 0
-		for _, m := range n.msgs {
-			if strings.Contains(m, "removed 1 symlink(s)") {
-				delivered++
-			}
-			if i := strings.Index(m, "): "); i >= 0 && strings.Contains(m, "suppressed") {
-				var c int
-				_, _ = fmt.Sscanf(m[i+3:], "%d", &c)
-				counted += c
-			}
-		}
-		return delivered+counted == plants
-	}, 5*time.Second, 10*time.Millisecond, "delivered %d + counted %d of %d", delivered, counted, plants)
-}
-
-// An alert still queued when Watch stops (its send failed, the notifier has
-// since recovered, the retry tick has not come) is flushed once more before
-// Watch returns, on a ctx that is not the cancelled one: toggleNotifier fails
-// on a done ctx, as the real ntfy notifier does.
-func TestWatchFinalFlushSendsAQueuedAlertOnACtxThatOutlivesTheCancel(t *testing.T) {
-	brain := t.TempDir()
-	n := &toggleNotifier{}
-	n.down.Store(true)
-	ctx, cancel := context.WithCancel(context.Background())
-	done := make(chan struct{})
-	go func() { Watch(ctx, brain, 300*time.Millisecond, n); close(done) }()
-	link := filepath.Join(brain, "queued")
-	require.NoError(t, os.Symlink(t.TempDir(), link))
-	waitGone(t, link)
-	time.Sleep(20 * time.Millisecond) // let the immediate send fail
-	n.down.Store(false)
-	cancel()
-	<-done
-	assert.Equal(t, 1, n.count(), "the queued alert was not flushed at shutdown")
-}
-
-// lockedBuffer is a goroutine-safe log sink: Watch goroutines of earlier
-// tests may still log while one test captures.
-type lockedBuffer struct {
-	mu  sync.Mutex
-	buf bytes.Buffer
-}
-
-func (b *lockedBuffer) Write(p []byte) (int, error) {
-	b.mu.Lock()
-	defer b.mu.Unlock()
-	return b.buf.Write(p)
-}
-
-func (b *lockedBuffer) String() string { b.mu.Lock(); defer b.mu.Unlock(); return b.buf.String() }
-
-func captureLog(t *testing.T) *lockedBuffer {
-	t.Helper()
-	b := &lockedBuffer{}
-	prev := slog.Default()
-	slog.SetDefault(slog.New(slog.NewTextHandler(b, nil)))
-	t.Cleanup(func() { slog.SetDefault(prev) })
-	return b
-}
-
-// PR #180 round 2: when the final flush fails (ntfy hung at shutdown) the
-// undelivered alerts vanished with only "will retry" warnings. Watch now logs
-// one error with both counts.
-func TestWatchLogsUndeliveredAndSuppressedCountsWhenTheFinalFlushFails(t *testing.T) {
-	prev := shutdownFlushTimeout
-	shutdownFlushTimeout = 50 * time.Millisecond
-	t.Cleanup(func() { shutdownFlushTimeout = prev })
-	logs := captureLog(t)
-	brain := t.TempDir()
-	ctx, cancel := context.WithCancel(context.Background())
-	done := make(chan struct{})
-	go func() { Watch(ctx, brain, 5*time.Millisecond, hungNotifier{latency: time.Hour}); close(done) }()
-	link := filepath.Join(brain, "lost")
-	require.NoError(t, os.Symlink(t.TempDir(), link))
-	waitGone(t, link)
-	cancel()
-	<-done
-	out := logs.String()
-	assert.Contains(t, out, "level=ERROR")
-	assert.Contains(t, out, `msg="symlink tripwire alerts not delivered at shutdown"`)
-	assert.Contains(t, out, "undelivered=1")
-	assert.Contains(t, out, "suppressed=0")
-}
-
-// deliver, given a handoff that already holds alerts and is closed, moves them
-// into the queue and runs the final flush, even though the ctx is cancelled:
-// the drain-on-close path, without depending on when the close lands.
-func TestDeliverFlushesAlertsDrainedFromAClosedHandoffOnACancelledCtx(t *testing.T) {
-	alerts := make(chan string, 3)
-	alerts <- "a1"
-	alerts <- "a2"
-	close(alerts)
-	ctx, cancel := context.WithCancel(context.Background())
-	cancel()
-	n := &toggleNotifier{}
-	var overflow atomic.Int64
-	deliver(ctx, time.Hour, n, alerts, &overflow)
-	assert.Equal(t, []string{"a1", "a2"}, n.msgs)
-}
-
-// PR #180 round 2: when the first receive after close finds the handoff empty,
-// overflow counted by the scan was never moved into the summary.
-func TestDeliverCountsOverflowWhenTheHandoffIsClosedAndEmpty(t *testing.T) {
-	alerts := make(chan string)
-	close(alerts)
-	n := &recNotifier{}
-	var overflow atomic.Int64
-	overflow.Store(3)
-	deliver(context.Background(), time.Hour, n, alerts, &overflow)
-	require.Len(t, n.msgs, 1)
-	assert.Contains(t, n.msgs[0], "3 further alert(s)")
-}