fix: event-loop freezes, plugin-install boot crash, tmux attach/scrollbar, Codex transcripts

- GET /api/workflows: one LEAD() window pass in a read worker (read-pool.js,
  workflow-stats.js); idx_events_session restored, idx_events_tool added
- compat-sqlite gains function/pluck/readonly so a plugin install without a
  better-sqlite3 build boots again; antigravity-usage uses db.js's Database
- install-hooks adds no checkout hooks while the agenthub plugin is enabled
  (events were doubled)
- terminal attach runs the live tmux server's own binary; the pane scrollbar
  gets a visible 2-column style, and claude panes start with
  CLAUDE_CODE_DISABLE_ALTERNATE_SCREEN=1 so tmux keeps history to scroll
- Codex sessions' conversation in GET /api/sessions/:id/transcript
- Codex/Antigravity sessions claimed by their workspace without hooks
- UI-audit follow-ups, docs and OpenAPI

server/lib/tmux.js

@@ -49,6 +49,16 @@ function hasSession(name) {
   }
 }
 
+/** The running tmux server's pid, or null when none answers. */
+function serverPid() {
+  try {
+    const pid = String(execImpl(["display-message", "-p", "#{pid}"])).trim();
+    return /^\d+$/.test(pid) ? pid : null;
+  } catch {
+    return null;
+  }
+}
+
 /** `-e NAME=value` pairs for tmux, in a stable order. */
 function envFlags(env) {
   const flags = [];
@@ -77,8 +87,29 @@ function newSession({ name, cwd, argv, env }) {
 // Called on every attach (not just at creation) so a session started before
 // this option existed — or before a server restart picked up the change —
 // still gets it; `set-option` is idempotent, so re-running it is harmless.
+// The status bar goes off here too: the dashboard's tab bar already names the
+// pane, and tmux's green line only eats a row of the terminal.
 function enableMouse(name) {
   execImpl(["set-option", "-t", pane(name), "mouse", "on"]);
+  execImpl(["set-option", "-t", pane(name), "status", "off"]);
+  // A draggable scrollbar beside the pane (mouse mode makes it drag). Only a
+  // tmux SERVER of 3.7+ knows the option; an older one refuses it, which is
+  // fine — the pane just has none (`/agenthub-doctor` says how to upgrade).
+  try {
+    execImpl(["set-option", "-t", pane(name), "pane-scrollbars", "on"]);
+    // tmux's default (`fg=white,bg=black,width=1`) is a one-column track in
+    // ANSI black — the terminal theme's border colour, almost the background —
+    // so it reads as no scrollbar at all. Two columns, bright slider.
+    execImpl([
+      "set-option",
+      "-t",
+      pane(name),
+      "pane-scrollbars-style",
+      "fg=brightwhite,bg=black,width=2,pad=0",
+    ]);
+  } catch {
+    /* tmux < 3.7 */
+  }
 }
 
 /**
@@ -174,11 +205,27 @@ function listSessions(prefix) {
 }
 
 function isTmuxAvailable() {
+  return clientVersion() !== null;
+}
+
+/** The tmux binary's version (`3.7c`, `next-3.8`), null when it is absent. */
+function clientVersion() {
   try {
-    execImpl(["-V"]);
-    return true;
+    return execImpl(["-V"])
+      .trim()
+      .replace(/^tmux\s+/, "");
   } catch {
-    return false;
+    return null;
+  }
+}
+
+/** The RUNNING server's version, null when none runs. A server started before
+ *  an upgrade keeps its old version until every tmux session has closed. */
+function serverVersion() {
+  try {
+    return execImpl(["display-message", "-p", "#{version}"]).trim() || null;
+  } catch {
+    return null;
   }
 }
 
@@ -193,6 +240,9 @@ module.exports = {
   killSession,
   listSessions,
   isTmuxAvailable,
+  clientVersion,
+  serverVersion,
+  serverPid,
   __setExecImpl,
   __reset,
 };