fixed freezing on session resume

README.md

@@ -2,8 +2,6 @@
 
 Async subagents for [pi](https://github.com/badlogic/pi-mono) — spawn, orchestrate, and manage sub-agent sessions in multiplexer panes. **Fully non-blocking** — the main agent keeps working while subagents run in the background.
 
-https://github.com/user-attachments/assets/30adb156-cfb4-4c47-84ca-dd4aa80cba9f
-
 ## How It Works
 
 Call `subagent()` and it **returns immediately**. The sub-agent runs in its own terminal pane. A live widget above the input shows all running agents with their current state — `starting`, `active`, `waiting`, `stalled`, or `running`. When a sub-agent finishes, its result is **steered back** into the main session as an async notification — triggering a new turn so the agent can process it.
@@ -23,33 +21,6 @@ subagent({ name: "Scout: DB", agent: "scout", task: "Map database schema" });
 // Both return immediately, results steer back independently
 ```
 
-## Install
-
-```bash
-pi install git:github.com/HazAT/pi-interactive-subagents
-```
-
-Supported multiplexers:
-
-- [cmux](https://github.com/manaflow-ai/cmux)
-- [tmux](https://github.com/tmux/tmux)
-- [zellij](https://zellij.dev)
-- [WezTerm](https://wezfurlong.org/wezterm/) (terminal emulator with built-in multiplexing)
-
-Start pi inside one of them:
-
-```bash
-cmux pi
-# or
-tmux new -A -s pi 'pi'
-# or
-zellij --session pi   # then run: pi
-# or
-# just run pi inside WezTerm — no wrapper needed
-```
-
-Optional: set `PI_SUBAGENT_MUX=cmux|tmux|zellij|wezterm` to force a specific backend.
-
 If your shell startup is slow and subagent commands sometimes get dropped before the prompt is ready, set `PI_SUBAGENT_SHELL_READY_DELAY_MS` to a higher value (defaults to `500`):
 
 ```bash

agents/researcher.md

@@ -2,7 +2,7 @@
 name: researcher
 description: Web researcher — searches the web and synthesizes findings
 tools: web_search, web_fetch
-model: anthropic/claude-sonnet-4-6
+model: openrouter/z-ai/glm-5.2
 thinking: medium
 system-prompt: append
 auto-exit: true

agents/scout.md

@@ -2,8 +2,8 @@
 name: scout
 description: Fast codebase recon — explores files, finds patterns, maps architecture
 tools: read, grep, find, ls
-model: anthropic/claude-haiku-4-5
-thinking: medium
+model: openrouter/z-ai/glm-5.2
+thinking: low
 system-prompt: append
 auto-exit: true
 ---

agents/worker.md

@@ -3,7 +3,7 @@ name: worker
 description: General-purpose worker — reads, writes, and edits code
 tools: read, write, edit, safe_bash, web_search, web_fetch
 subagent_agents: scout, researcher
-model: anthropic/claude-sonnet-4-6
+model: openrouter/z-ai/glm-5.2
 thinking: medium
 system-prompt: append
 ---

pi-extension/subagents/session.ts

@@ -1,9 +1,12 @@
 import {
   appendFileSync,
+  closeSync,
   copyFileSync,
   existsSync,
   mkdirSync,
+  openSync,
   readFileSync,
+  readSync,
   readdirSync,
   statSync,
   writeFileSync,
@@ -99,30 +102,44 @@ export function getLeafId(sessionFile: string): string | null {
  * then prefix), NOT the filename — so this is the value to hand back to the
  * orchestrator for follow-ups.
  */
-export function getSessionId(sessionFile: string): string | null {
+/**
+ * Read only the first line of a file without loading the whole thing into
+ * memory. Session files grow to many MB, but the header we need is always the
+ * first JSON line, so reading a small prefix keeps header lookups cheap — this
+ * is what makes scanning a large session tree fast enough to avoid blocking the
+ * event loop. Returns the first line (sans trailing newline), or null.
+ */
+function readFirstLine(path: string, maxBytes = 65536): string | null {
+  let fd: number | undefined;
   try {
-    const raw = readFileSync(sessionFile, "utf8");
-    for (const line of raw.split("\n")) {
-      const trimmed = line.trim();
-      if (!trimmed) continue;
-      const entry = JSON.parse(trimmed) as { type?: string; id?: string };
-      if (entry.type === "session" && typeof entry.id === "string") {
-        return entry.id;
-      }
-      // Header is always the first entry; bail after the first parse.
-      break;
-    }
+    fd = openSync(path, "r");
+    const buf = Buffer.allocUnsafe(maxBytes);
+    const bytes = readSync(fd, buf, 0, maxBytes, 0);
+    if (bytes <= 0) return null;
+    const nl = buf.indexOf(0x0a); // '\n'
+    const end = nl === -1 || nl >= bytes ? bytes : nl;
+    return buf.toString("utf8", 0, end);
   } catch {
-    // fall through
-  }
     return null;
+  } finally {
+    if (fd !== undefined) {
+      try {
+        closeSync(fd);
+      } catch {
+        /* ignore */
+      }
+    }
+  }
+}
+
+export function getSessionId(sessionFile: string): string | null {
+  return readHeaderId(sessionFile);
 }
 
 function readHeaderId(sessionFile: string): string | null {
-  try {
-    const raw = readFileSync(sessionFile, "utf8");
-    const firstLine = raw.split("\n", 1)[0]?.trim();
+  const firstLine = readFirstLine(sessionFile)?.trim();
   if (!firstLine) return null;
+  try {
     const entry = JSON.parse(firstLine) as { type?: string; id?: string };
     return entry.type === "session" && typeof entry.id === "string" ? entry.id : null;
   } catch {