A project kept on an ExFAT/FAT external volume (or some network mounts /
WSL2 DrvFs) broke the background auto-sync daemon at two points, both
because the filesystem lacks POSIX features the daemon relied on:
1. Lock acquisition hard-links a temp file onto .codegraph/daemon.pid for
race-free exclusivity (#411) — these filesystems have no hard links.
2. The Unix-domain socket listen() fails regardless of path length, so the
old length-only tmpdir fallback never triggered.
Both surface as a capability error, but each OS reports a DIFFERENT errno
for the same gap (macOS ENOTSUP, Linux EPERM, Windows EISDIR), so the fix
is policy-based rather than an enumerated code-set:
- Lock: fall back to an O_EXCL create on any non-EEXIST link error. The
temp write already proved the directory is writable, so the fallback
either succeeds (still atomic + exclusive, "first writer wins") or
surfaces its own genuine error.
- Socket: an ordered candidate list [in-project, tmpdir] walked by BOTH
the daemon (binds) and the proxy (connects) — they converge on the
fallback with zero coordination. Relocate past any non-EADDRINUSE bind
error; EADDRINUSE still rethrows, preserving the #974 contract.
Normal repos are unaffected: the in-project candidate binds first, and the
hard-link lock path is unchanged.
Validated end-to-end on real removable-drive filesystems: macOS ExFAT
(hdiutil image), Linux FAT32 (Docker loop mount), Windows exFAT (diskpart
VHD) — each acquires the lock, relocates (or binds a named pipe on
Windows), and serves a real client.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
One shared, detached daemon per project root: every `codegraph serve --mcp` is a thin stdio<->socket proxy (Unix socket / Windows named pipe) to it, so N agents in one repo share a single file watcher, SQLite connection, and tree-sitter warm-up instead of N copies. The daemon outlives any single session and reaps via client-refcount + idle timeout; `CODEGRAPH_NO_DAEMON=1` opts out.
Hardened during review: detached-process lifecycle (preserves the #277 watchdog via the proxy; the daemon no longer orphans on host SIGKILL), atomic lockfile + pid-verified stale-clear (no double-daemon on concurrent startup), realpath root canonicalization. Validated on macOS, Linux (Docker - 3x fewer inotify watches for 3 agents), and Windows (named pipes); A/B confirms byte-identical tool output vs direct mode. Closes#411.
Co-Authored-By: Colby McHenry <me@colbymchenry.com>
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
