fix(mcp): start the daemon on ExFAT/FAT/network filesystems (#997) (#1022)

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>

CHANGELOG.md

@@ -21,6 +21,7 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 - A `codegraph index` or `codegraph init` that gets orphaned or wedged now stops itself instead of pinning a CPU core forever. If you killed the command (or the terminal/agent that launched it), the underlying indexer process used to keep running in the background — the parent couldn't pass the signal along — and a genuinely stuck index had nothing watching it either, since the self-recovery watchdogs were wired only into the background MCP server. Both gaps are closed: indexing now self-terminates when its parent goes away, and a main thread that stops making progress is killed so it can't hang indefinitely. Opt out with `CODEGRAPH_NO_WATCHDOG=1` (liveness) or `CODEGRAPH_PPID_POLL_MS=0` (orphan detection), matching the server. (#999)
 - Indexing no longer hangs at "Resolving refs" on a repo that commits a large JavaScript/TypeScript theme or SDK. A vendored admin theme (Metronic is the classic case — ~1,300 committed `.js` files) re-declares the same method names (`init`, `update`, `render`, `destroy`, …) on hundreds of widgets, and resolution used to score *every* same-named definition against *every* call — work that grows with the square of how many times a name repeats. On such a repo it pinned a CPU core for 15–30 minutes and effectively never finished. Resolution now declines to guess when a name is defined more times than any real codebase ever repeats one (the cutoff is generous — normal projects top out far below it and are completely unaffected), since no proximity heuristic can pick the one true target among thousands anyway. Indexing that previously wedged now completes in seconds, and precise resolution (imports, qualified names, class-name matches) is unchanged. This is the same class of slowdown as the 1.1.0 import-name fix, now closed for repeated method/symbol names. Tune the cutoff with `CODEGRAPH_AMBIGUOUS_NAME_CEILING` if you ever need to. Thanks @DANOX2 for the detailed report and repro. (#999)
 - Claude Code's front-load prompt hook now fires for non-English prompts. The optional hook that injects CodeGraph context for structural questions only recognized English keywords, so a structural question written in Chinese — or any non-Latin-script language — silently injected nothing: the hook looked like it wasn't wired up despite a correct setup, with no error to explain why. The gate is now language-aware. It recognizes Chinese structural keywords (如何/流程/调用/依赖/实现/架构…), and — in any language — a prompt that names a real code symbol from your project, such as `getUserId`, `article_publish`, `user.login`, or `parseToken()` (the name is checked against the index, so an ordinary word that merely looks like code doesn't trigger it). Non-structural prompts ("fix this typo", in any language) stay a no-op as before, so nothing fires where there's no structural answer to give. Thanks @whinc for the detailed report and repro. (#994)
+- The background auto-sync server now starts for projects kept on an ExFAT or FAT external drive (and some network mounts). Those filesystems don't support the operations the server relies on to coordinate and to listen locally, so it failed immediately and re-logged the same error on every retry — background indexing was broken, so you had to run `codegraph sync` by hand after changes. (The MCP tools, the prompt hook, and manual `codegraph index`/`sync` were unaffected, since none of them need the server.) The server now works around those limitations automatically — falling back to a different coordination method and relocating its local socket to your system temp directory — so background indexing works there exactly like anywhere else, with no configuration needed. Verified end-to-end on real removable-drive filesystems on macOS, Linux, and Windows. Thanks @zengwenliang416 for the detailed report. (#997)
 
 
 ## [1.1.1] - 2026-06-24