Fix main-document switching end to end; stable project-independent MCP pathHEADmain

Main document: the app never called Overleaf's official settings endpoint,
so "Set as main document" only changed renderer state and agents had no way
to switch at all — compiles kept using the old root. Now:
- Right-click Set as main and the new set_main_file MCP tool both POST
  /project/:id/settings {rootDocId} (web parity, persists project-wide)
- Handle the rootDocUpdated broadcast: update the project snapshot, the
  renderer state, and rewrite CLAUDE.md/AGENTS.md — the guide's stale
  "Main file" line was teaching agents to compile the old root via
  main_file overrides
- Compile root resolution uses the sync bridge's live maps, so docs
  created mid-session resolve correctly (agent guide too)

MCP server location: Codex stores its MCP registration globally, and the
per-project path went stale when the project temp dir was cleaned up
("connection closed" on handshake). The bundled server now installs to
~/.lattex/lattex-mcp.mjs (project-independent, refreshed on connect; the
esbuild bundle since the raw source can't resolve node_modules from there)
and resolves the project at runtime: $LATTEX_PROJECT_DIR, cwd + ancestors,
legacy script location, then single live project in tmpdir. Register once,
works for every project.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/main/fileSyncBridge.ts b/src/main/fileSyncBridge.ts
index 08bf69e..7de04d7 100644
--- a/src/main/fileSyncBridge.ts
+++ b/src/main/fileSyncBridge.ts
@@ -1785,6 +1785,17 @@ export class FileSyncBridge {
     return Object.entries(this.fileRefPathMap).map(([id, path]) => ({ id, path }))
   }
 
+  /** Live docId → relPath lookup — unlike the connect-time project snapshot,
+   *  this includes docs created mid-session */
+  getDocPath(docId: string): string | undefined {
+    return this.docPathMap[docId]
+  }
+
+  /** Live relPath → docId lookup (see getDocPath) */
+  getDocIdForPath(relPath: string): string | undefined {
+    return this.pathDocMap[relPath]
+  }
+
   /** Check if a doc's content is known */
   hasDoc(relPath: string): boolean {
     return this.lastKnownContent.has(relPath)