fix(pi): add snap node compatibility diagnostics and documentation

- Added detailed error logging to detect snap node compatibility issues
- When Pi process exits with code 1, log helpful diagnostic info including node path
- Add hint to check for snap node and reinstall via apt/nvm
- Create SNAP_NODE_COMPATIBILITY.md with full troubleshooting guide
- Document root cause: snap node has file descriptor incompatibility with Bun.spawn stdin pipes
- Provide clear installation instructions for NodeSource and nvm alternatives

src/servers/channels/send-and-await.ts

@@ -91,7 +91,10 @@ export async function sendAndAwait(params: SendAndAwaitParams): Promise<SendAndA
   const lockPromise = new Promise<void>((resolve) => {
     releaseLock = resolve;
   });
-  sessionLocks.set(sessionId, existing.then(() => lockPromise));
+  sessionLocks.set(
+    sessionId,
+    existing.then(() => lockPromise),
+  );
 
   await existing;
 
@@ -291,23 +294,18 @@ async function doSend(sessionId: string, params: SendAndAwaitParams): Promise<Se
     (async () => {
       try {
         if (!session.piProcess) {
-          let spawnOptions: { sessionFile?: string } | undefined;
+          let spawnOptions: { sessionFile?: string; username?: string } | undefined;
           if (session.messages.length > 0) {
             await storage.saveSession(homeDir, sessionId, session.meta, session.messages);
             const hostPath = await storage.getSessionFilePath(homeDir, sessionId);
             if (hostPath) {
-              // Remap host path to container path
-              const containerHome = `/home/${username}`;
-              const sessionsPrefix = join(homeDir, '.pi', 'agent', 'sessions');
-              const relativePart = hostPath.slice(sessionsPrefix.length);
-              spawnOptions = { sessionFile: `${containerHome}/.pi/agent/sessions${relativePart}` };
+              spawnOptions = { sessionFile: hostPath, username };
             }
           }
+          if (!spawnOptions) spawnOptions = { username };
 
           const dispatcher = createDispatcher(sessionId);
-          const sandbox = { userId, username, email, homeDir };
-          session.piProcess = await piBridge.spawnPi(cwd, model!, userId, email, dispatcher, sandbox, spawnOptions);
-          session.sandboxed = true;
+          session.piProcess = await piBridge.spawnPi(cwd, model!, userId, email, dispatcher, spawnOptions);
 
           const proc = session.piProcess;
           proc.exited.then(() => {