Bidirectional autosync for local-mount by willwashburn · Pull Request #49 · AgentWorkforce/relayfile

willwashburn · 2026-04-19T00:12:02Z

Summary

Adds @relayfile/local-mount auto-sync: chokidar watchers on both the mount and project trees plus a periodic full-scan safety net, so edits propagate continuously during a CLI run instead of only at exit.
New startAutoSync() on the mount handle and an autoSync option on launchOnMount (enabled by default; pass false to opt out or an options object to tune scanIntervalMs / writeFinishMs).
Conflict rule is "mount wins": both sides changed since last sync → mount→project; one side deleted with the other unchanged → propagate the delete; readonly paths only flow project→mount.

Test plan

npx tsc --noEmit in packages/local-mount
npx vitest run in packages/local-mount (21/21 pass, including 10 new autosync tests)
Smoke-test: run an agent CLI under launchOnMount and verify edits from the agent show up in the project dir while the CLI is still running
Smoke-test: edit a file in the project dir during a run and verify the change appears in the mount

🤖 Generated with Claude Code

Introduce a new autosync subsystem to keep mount↔project files in sync. Adds packages/local-mount/src/auto-sync.ts implementing a chokidar-based watcher + periodic reconcile with mount-wins resolution, readonly/ignored/excluded handling, safe write targets, and lifecycle APIs (start/stop/reconcile/ready/totalChanges). Exposes AutoSync types from the package index and wires a startAutoSync() method into the symlink mount handle. Integrates auto-sync into the launch flow via an autoSync option that runs during the spawned CLI and aggregates auto-sync changes into final sync counts. Adds comprehensive tests (auto-sync.test.ts) and records the chokidar dependency in package.json.

Update packages/local-mount/README.md to document the new auto-sync functionality and API surface. Adds startAutoSync to SymlinkMountHandle and describes AutoSyncOptions and AutoSyncHandle. Updates launchOnMount behavior to start/stop bidirectional auto-sync (or disable it), documents onAfterSync semantics, outlines how auto-sync works (chokidar + periodic reconcile, mtime tracking), lists conflict/delete rules and readonly/ignored path behavior, and clarifies that syncBack is a one-shot mount-only pass that writes files (never deletes).

Copilot

Pull request overview

Adds bidirectional, in-process autosync to @relayfile/local-mount so changes propagate continuously during a CLI run rather than only syncing back on exit.

Changes:

Introduces a new startAutoSync() API on SymlinkMountHandle implemented via chokidar watchers plus a periodic full reconcile.
Extends launchOnMount with an autoSync option (default enabled) to run autosync for the lifetime of the spawned CLI.
Adds Vitest coverage for autosync behavior and adds chokidar as a dependency.

Reviewed changes

Copilot reviewed 7 out of 8 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
packages/local-mount/src/symlink-mount.ts	Plumbs autosync context + exposes `startAutoSync()` on the mount handle.
packages/local-mount/src/launch.ts	Starts/stops autosync around the spawned CLI; aggregates sync counts.
packages/local-mount/src/index.ts	Re-exports autosync public types.
packages/local-mount/src/auto-sync.ts	New autosync implementation (watchers + reconcile + conflict rules).
packages/local-mount/src/auto-sync.test.ts	New tests for bidirectional syncing, readonly/ignored behavior, and reserved files.
packages/local-mount/package.json	Adds `chokidar` dependency.
package-lock.json	Locks `chokidar` and `readdirp` versions.

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willwashburn · 2026-04-19T00:40:53Z

+      let autoSyncChanges = 0;
+      if (autoSync) {
+        await autoSync.stop();
+        autoSyncChanges = autoSync.totalChanges();
+        autoSync = undefined;
+      }
+      const finalSynced = await handle.syncBack();
+      syncedCount = autoSyncChanges + finalSynced;


Updated the doc comment in 96e690c to reflect that syncedFileCount is the total across both directions (autosync activity + final syncBack) rather than a strict mount→project count. The broader meaning is more useful as an "anything changed?" signal for callers — kept the aggregation but realigned the contract.

willwashburn · 2026-04-19T00:40:55Z

+function primeState(state: Map<string, FileState>, ctx: AutoSyncContext): void {
+  // Record current mtimes for every file that exists in both trees. Files that
+  // differ, or exist on only one side, are left out so the first reconcile
+  // treats them as changed and syncs them.
+  walk(ctx.realMountDir, ctx, (abs) => {
+    const rel = toRelPosix(abs, ctx);
+    if (rel === null) return;
+    if (!isSyncCandidate(rel, ctx)) return;
+    const mountStat = safeFileStat(abs);
+    if (!mountStat) return;
+    const projectAbs = path.join(ctx.realProjectDir, rel);
+    const projectStat = safeFileStat(projectAbs);
+    if (!projectStat) return;
+    state.set(rel, {
+      mountMtimeMs: mountStat.mtimeMs,
+      projectMtimeMs: projectStat.mtimeMs,
+    });


Good catch — fixed in 96e690c by adding a sameContent check before seeding state. Files that differ at startup are now left out, so the first reconcile sees no prev entry and goes through the content-based resolution path.

willwashburn · 2026-04-19T00:40:57Z

+    const changed = syncOneFile(relPosix, state, ctx);
+    if (changed) count += 1;


Fixed in 96e690c. visit() now wraps syncOneFile in try/catch and forwards errors to onError, so one bad path no longer aborts the whole reconcile pass. reconcile() takes onError as a parameter.

willwashburn · 2026-04-19T00:40:59Z

+  const target = resolveSafeWriteTarget(ctx.realProjectDir, projectAbs);
+  if (!target) return false;
+  if (existsSync(target) && sameContent(mountAbs, target)) {
+    updateState(state, relPosix, mountAbs, target);
+    return false;
+  }
+  copyFileSync(mountAbs, target);
+  updateState(state, relPosix, mountAbs, target);


Fixed in 96e690c. Added an isSymlinkTarget check in both doMountToProject and doProjectToMount — if the target already exists as a symlink, we refuse to write through it. Matches syncBacks behavior and blocks writes from escaping the root.

willwashburn · 2026-04-19T00:41:00Z

+    ? prev?.mountMtimeMs === undefined || mountStat.mtimeMs > prev.mountMtimeMs
+    : false;
+  const projectChanged = projectStat
+    ? prev?.projectMtimeMs === undefined || projectStat.mtimeMs > prev.projectMtimeMs


Fixed in 96e690c — switched both mountChanged and projectChanged to !==. Coarse-resolution or backdated writes no longer get silently skipped during periodic reconciles.

noodleonthecape

Nice change. I pulled this locally, ran the @relayfile/local-mount typecheck and test suite, and spot-checked the auto-sync logic plus coverage. The mount/project conflict handling, readonly behavior, reserved-file exclusions, and launch lifecycle all look solid to me.

devin-ai-integration

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.

- primeState now skips files whose content differs at startup, so the first reconcile actually resolves initial drift (previously seeded matching mtimes and then suppressed the sync) - reconcile() isolates per-path errors so one bad path no longer aborts the whole pass; errors are surfaced via onError - doMountToProject / doProjectToMount refuse to write through a target that already exists as a symlink, matching syncBack's behavior and preventing writes from escaping the root - mtime change detection uses !== instead of > so coarse-resolution or backdated writes aren't silently missed during periodic reconciles - Clarified onAfterSync doc: the count is now total changes in both directions (autosync + final syncBack), not a strict mount→project tally Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

AutoSyncContext.isIgnored's lambda in symlink-mount always OR'd the file-form and directory-form match, so a regular file whose path matched a directory-only pattern (e.g. `cache/`) was incorrectly ignored by autosync. The initial mount walk already distinguished the two via `entry.isDirectory()`, so the bug only affected the autosync path. - AutoSyncContext.isIgnored now accepts an optional `isDirectory` flag; symlink-mount constructs it as a thin pass-through to `isPathMatched` - walk() in auto-sync.ts passes `entry.isDirectory()` to isIgnored - isSyncCandidate() keeps the default (file), matching its callers - shouldChokidarIgnore() uses chokidar's optional `stats` second arg when available so dir-form matches are only applied to actual directories. Without stats (pre-stat prune call) we fall back to file-form to avoid false-positive pruning; chokidar calls the filter a second time with stats so pruning still happens at the directory level - Regression test covers `cache/` pattern with a file at `docs/cache` Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

willwashburn added 2 commits April 18, 2026 20:11

Merge branch 'main' into auto-sync-mount

6f0f346

willwashburn requested review from Copilot and khaliqgant April 19, 2026 00:14

Copilot started reviewing on behalf of willwashburn April 19, 2026 00:15 View session

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noodleonthecape approved these changes Apr 19, 2026

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willwashburn merged commit 5389315 into main Apr 19, 2026
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willwashburn deleted the auto-sync-mount branch April 19, 2026 01:56

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Bidirectional autosync for local-mount#49

Bidirectional autosync for local-mount#49
willwashburn merged 5 commits intomainfrom
auto-sync-mount

willwashburn commented Apr 19, 2026 •

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		const changed = syncOneFile(relPosix, state, ctx);
		if (changed) count += 1;

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willwashburn commented Apr 19, 2026 • edited by devin-ai-integration bot Loading Uh oh! There was an error while loading. Please reload this page.

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willwashburn commented Apr 19, 2026 •

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