fix(edit-history): bounded image probe, linear path scan (review of #693)

- probeLocalPaths: every agent-printed candidate goes through
  probePathKind() first (no pastCap, bulk scan), sequentially; only a path
  that answered 'file' gets realpath + stat. A path on a mount that stopped
  answering no longer hangs the sync, a queued sync or remove().
- PATH_TOKEN_RE: branch 4 starts only at a token boundary (`:` excluded so
  URLs stay ignored), branch 1 stops at `:`. Linear in the line length
  (30,000 `#` took ~3 s before).
- Load older yields to the event loop between the files it parses.
- GET /edits answers unsupported without loading a store.
- CLAUDE.md paragraph trimmed to the rules; probe and regex rules added to
  architecture-invariants#edit-history-panel.

Tests: stall test through the real sync and probe with a stat that never
settles; time-budget tests with 30,000-character inputs and a 139-result
base64 chunk; route test asserts no store load for unsupported sessions.

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

test/edit-history-local-source.test.ts

@@ -141,12 +141,25 @@ describe('readClaudeEditSources', () => {
 });
 
 describe('probeLocalPaths', () => {
-  it('reports kind, size and mtime, expands ~/ against home, null for missing', async () => {
+  it('reports size and mtime of files, expands ~/ against home, null for missing and directories', async () => {
     put('home/img.png', 'PNG!', 1_700_000_000);
     mkdirSync(join(root, 'dir'));
     const res = await probeLocalPaths(['~/img.png', join(root, 'dir'), join(root, 'nope.png')], join(root, 'home'));
     expect(res[0]).toEqual({ realPath: join(root, 'home/img.png'), kind: 'file', size: 4, mtimeMs: 1_700_000_000_000 });
-    expect(res[1]).toMatchObject({ kind: 'directory', size: 0 });
+    expect(res[1]).toBeNull();
     expect(res[2]).toBeNull();
   });
+
+  it('touches a path only after the bounded probe saw a file there', async () => {
+    put('a.png', 'PNG!', 1_700_000_000);
+    put('b.png', 'PNG!', 1_700_000_000);
+    const asked: string[] = [];
+    const res = await probeLocalPaths([join(root, 'a.png'), join(root, 'b.png'), 'rel.png'], root, async (p) => {
+      asked.push(p);
+      return p.endsWith('a.png') ? 'unknown' : 'file';
+    });
+    // a.png exists, but its filesystem did not answer the bounded probe: no unbounded stat.
+    expect(res.map((r) => r?.realPath ?? null)).toEqual([null, join(root, 'b.png'), null]);
+    expect(asked).toEqual([join(root, 'a.png'), join(root, 'b.png')]); // relative: never probed
+  });
 });

test/edit-history-parse.test.ts

@@ -349,6 +349,50 @@ describe('extractImagePathCandidates', () => {
   });
 });
 
+describe('extractImagePathCandidates: linear in the line length (#693 review)', () => {
+  // Claude Code keeps up to 30,000 characters of Bash output, all of it agent-printed, and the
+  // scan runs synchronously in the request. Before the fix one such line took ~2.7 s.
+  const N = 30_000;
+  const BUDGET_MS = 250;
+  const timed = (text: string) => {
+    const t = performance.now();
+    const out = extractImagePathCandidates('render', text, '', CWD);
+    return { out, ms: performance.now() - t };
+  };
+  const base64 = Buffer.from(Array.from({ length: (N * 3) / 4 }, (_, i) => (i * 131 + 7) & 255)).toString('base64');
+
+  it.each([
+    ...'#+%@![{^:/a.~-$'.split('').map((c) => [`30,000 × ${c}`, c.repeat(N)] as const),
+    ['a base64 blob', base64] as const,
+    ['repeated file:///', 'file:///'.repeat(N / 8)] as const,
+    ['repeated file:///x', 'file:///x'.repeat(N / 9)] as const,
+    ['an unclosed quote', '"' + 'a'.repeat(N)] as const,
+    ['repeated =a', '=a'.repeat(N / 2)] as const,
+  ])('%s stays under the time budget and still finds a path after it', (_label, line) => {
+    const { out, ms } = timed(`${line}\nsaved out/plot.png`);
+    expect(ms).toBeLessThan(BUDGET_MS);
+    expect(out).toContain('/work/repo/out/plot.png');
+  });
+
+  it('parses a chunk of 139 Bash results with a 30,000-character base64 blob each under budget', () => {
+    const lines: string[] = [];
+    for (let i = 0; i < 139; i++) {
+      lines.push(bashUseLine(`toolu_${i}`, '2026-10-15T20:00:00.000Z', 'cat img.b64'));
+      lines.push(
+        toolResultLine(`toolu_${i}`, '2026-10-15T20:00:01.000Z', {
+          stdout: base64,
+          stderr: '',
+          interrupted: false,
+          isImage: false,
+        })
+      );
+    }
+    const t = performance.now();
+    parseClaudeEditLines(lines.join('\n'));
+    expect(performance.now() - t).toBeLessThan(1500);
+  });
+});
+
 describe('classifyEditPath', () => {
   it.each([
     ['/a/b.png', 'image'],

test/edit-history-probe-stall.test.ts

@@ -0,0 +1,106 @@
+/**
+ * Edit history image probe against a filesystem that stopped answering (#693 review): a Bash
+ * call printed a path on a dead hard mount, whose stat() never settles. The real sync with the
+ * real probe (`probeLocalPaths` → bounded `probePathKind`) must still finish, the next queued
+ * sync too, and `remove()` must not wait on it. Own file: the stalled probe stays recorded
+ * process-wide for the rest of the run.
+ */
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+
+const DEAD = '/mnt/dead-nas';
+
+vi.hoisted(() => {
+  process.env.CODEMAN_PATH_PROBE_TIMEOUT_MS = '100';
+});
+
+vi.mock('node:fs/promises', async (importOriginal) => {
+  const real = await importOriginal<typeof import('node:fs/promises')>();
+  const hangs = (p: unknown) => String(p).startsWith('/mnt/dead-nas');
+  const stat = ((p: Parameters<typeof real.stat>[0], ...rest: unknown[]) =>
+    hangs(p) ? new Promise(() => {}) : (real.stat as (...a: unknown[]) => unknown)(p, ...rest)) as typeof real.stat;
+  const realpath = ((p: Parameters<typeof real.realpath>[0], ...rest: unknown[]) =>
+    hangs(p)
+      ? new Promise(() => {})
+      : (real.realpath as (...a: unknown[]) => unknown)(p, ...rest)) as typeof real.realpath;
+  return { ...real, stat, realpath, default: { ...real, stat, realpath } };
+});
+
+import { mkdtempSync, rmSync, utimesSync, writeFileSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join } from 'node:path';
+import { EditHistoryStore } from '../src/edit-history-store.js';
+import { probeLocalPaths, type EditSources } from '../src/edit-history-local-source.js';
+import { EditHistorySync, type EditHistorySession } from '../src/web/edit-history-sync.js';
+
+const T0 = Date.parse('2026-10-15T20:00:00.000Z');
+const session: EditHistorySession = { id: 's1', mode: 'claude', remote: undefined, claudeSessionId: 'conv1' };
+
+function bashPair(id: string, start: number, end: number, stdout: string): string {
+  const use = {
+    type: 'assistant',
+    timestamp: new Date(start).toISOString(),
+    cwd: '/w',
+    message: { role: 'assistant', content: [{ type: 'tool_use', id, name: 'Bash', input: { command: 'render' } }] },
+  };
+  const res = {
+    type: 'user',
+    timestamp: new Date(end).toISOString(),
+    cwd: '/w',
+    message: { role: 'user', content: [{ tool_use_id: id, type: 'tool_result', content: stdout }] },
+    toolUseResult: { stdout, stderr: '', interrupted: false, isImage: false },
+  };
+  return JSON.stringify(use) + '\n' + JSON.stringify(res) + '\n';
+}
+
+/** Rejects after `ms`, so a hang fails the test instead of timing it out silently. */
+function within<T>(p: Promise<T>, ms: number, what: string): Promise<T> {
+  return Promise.race([
+    p,
+    new Promise<T>((_, reject) => setTimeout(() => reject(new Error(`${what} still pending after ${ms} ms`)), ms)),
+  ]);
+}
+
+let dir: string;
+let stores: string;
+beforeEach(() => {
+  dir = mkdtempSync(join(tmpdir(), 'edit-stall-'));
+  stores = join(dir, 'stores');
+});
+afterEach(() => {
+  rmSync(dir, { recursive: true, force: true });
+});
+
+describe('edit history image probe on an unresponsive mount', () => {
+  it('finishes sync, a queued sync and remove() while one printed path never answers', async () => {
+    const ok = join(dir, 'ok.png');
+    writeFileSync(ok, 'PNG!');
+    utimesSync(ok, new Date(T0 + 2000), new Date(T0 + 2000));
+    let main = Buffer.from(bashPair('b1', T0, T0 + 5000, `${DEAD}/plots/a.png\nsaved ${ok}\n`));
+
+    const sync = new EditHistorySync({
+      transcriptPath: async () => '/p/conv1.jsonl',
+      readSources: async (_path, requests, budget): Promise<EditSources> => {
+        const req = requests.find((r) => r.relPath === 'main');
+        const start = Math.min(req?.offset ?? 0, main.length);
+        const len = Math.min(budget, main.length - start);
+        return {
+          transcriptId: 'conv1',
+          files: [{ relPath: 'main', size: main.length, startOffset: start, chunk: main.subarray(start, start + len) }],
+          metas: {},
+        };
+      },
+      probe: (paths) => probeLocalPaths(paths),
+      loadStore: (id) => EditHistoryStore.load(id, { dir: stores, debounceMs: 0 }),
+      deleteStore: (id) => EditHistoryStore.delete(id, { dir: stores }),
+      sweepStores: async () => 0,
+    });
+
+    const first = sync.sync(session);
+    main = Buffer.concat([main, Buffer.from(bashPair('b2', T0 + 6000, T0 + 7000, `${DEAD}/plots/b.png\n`))]);
+    const second = sync.sync(session);
+    expect(await within(first, 1500, 'first sync')).toEqual({ state: 'ok' });
+    expect(await within(second, 1500, 'queued sync')).toEqual({ state: 'ok' });
+    expect((await sync.getStore('s1')).list().map((e) => e.path)).toEqual([ok]);
+    await within(sync.remove('s1'), 1500, 'remove()');
+  });
+});

test/routes/edit-history-routes.test.ts

@@ -186,12 +186,16 @@ describe('GET /api/sessions/:id/edits', () => {
     ['remote', { remote: { host: 'huff' } }],
     ['docker', { docker: { image: 'x' } }],
     ['mode', { mode: 'shell' }],
-  ])('answers unsupported (%s) without reading', async (reason, patch) => {
-    const { app, read } = await setup();
+  ])('answers unsupported (%s) without reading or loading a store', async (reason, patch) => {
+    const loadStore = vi.fn(async (id: string) => EditHistoryStore.load(id, { dir, debounceMs: 0 }));
+    const { app, read } = await setup({ loadStore });
     Object.assign(session, patch);
-    const data = (await app.inject({ method: 'GET', url: `${URL}?sync=1` })).json().data;
-    expect(data).toMatchObject({ state: 'unsupported', reason });
+    for (const url of [URL, `${URL}?sync=1`]) {
+      const data = (await app.inject({ method: 'GET', url })).json().data;
+      expect(data).toEqual({ state: 'unsupported', reason, backfillTruncated: false, agents: {}, entries: [] });
+    }
     expect(read).not.toHaveBeenCalled();
+    expect(loadStore).not.toHaveBeenCalled();
   });
 
   it('404s an unknown session', async () => {