fix: stream from current position, faster session detection (500ms)

- New sessions start from current file offset, not 0. Shows live
  thinking from the moment of detection, not a backlog dump.
- Session poll reduced from 2s to 500ms for faster pickup.
- Auto-pin with null body (MM pin API quirk).

src/session-monitor.js

@@ -34,7 +34,7 @@ class SessionMonitor extends EventEmitter {
   constructor(opts) {
     super();
     this.transcriptDir = opts.transcriptDir;
-    this.pollMs = opts.pollMs || 2000;
+    this.pollMs = opts.pollMs || 500;
     this.defaultChannel = opts.defaultChannel || null;
     this.logger = opts.logger || null;
 

src/status-watcher.js

@@ -51,6 +51,18 @@ class StatusWatcher extends EventEmitter {
   addSession(sessionKey, transcriptFile, initialState = {}) {
     if (this.sessions.has(sessionKey)) return;
 
+    // For new sessions (no saved offset), start from current file position
+    // so we only show NEW content going forward — not the entire backlog
+    let startOffset = initialState.lastOffset || 0;
+    if (!initialState.lastOffset) {
+      try {
+        var stat = fs.statSync(transcriptFile);
+        startOffset = stat.size;
+      } catch (_e) {
+        startOffset = 0;
+      }
+    }
+
     const state = {
       sessionKey,
       transcriptFile,
@@ -58,7 +70,7 @@ class StatusWatcher extends EventEmitter {
       startTime: initialState.startTime || Date.now(),
       lines: initialState.lines || [],
       pendingToolCalls: 0,
-      lastOffset: initialState.lastOffset || 0,
+      lastOffset: startOffset,
       lastActivityAt: Date.now(),
       agentId: initialState.agentId || extractAgentId(sessionKey),
       depth: initialState.depth || 0,
@@ -71,12 +83,14 @@ class StatusWatcher extends EventEmitter {
     this.fileToSession.set(transcriptFile, sessionKey);
 
     if (this.logger) {
-      this.logger.debug({ sessionKey, transcriptFile }, 'Session added to watcher');
+      this.logger.debug({ sessionKey, transcriptFile, startOffset }, 'Session added to watcher');
     }
 
-    // Immediately read any existing content
+    // Only read if we have a saved offset (recovery) — new sessions start streaming from current position
+    if (initialState.lastOffset) {
       this._readFile(sessionKey, state);
     }
+  }
 
   /**
    * Remove a session from watching.