perf: rest animations, cheaper chat typing and server polls, async per-tool hooks

UI
- No animation runs forever: Sagi moods, the custom pet sprite, status dots
  (pulse-dot, pulse-slow, ping) and the chat shimmer play a few cycles and
  rest. An infinite animation kept the browser drawing 60 frames a second.
- useSagiBrain: frames that only move lastActivityAt by <1 s keep the old
  state; the 1 s tick re-renders only when the mood changes.
- ConversationView and MessageList are memoized and PaneChat passes stable
  callbacks: typing in the chat box no longer re-renders the conversation.
- The chat's 700 ms menu poll reads plain text first and scans the terminal
  cell by cell (reusing one cell) only when a row could be a menu cursor row.

Server
- GET /sessions/:id/transcript?after=N skips lines <= N before JSON.parse.
- GET /sessions/:id/outline is cached until the session's events change.
- broadcastLane uses the cached tmux.liveSessions(); tmux.hasSession answers
  "yes" from the fresh shared list instead of a synchronous spawn (50-150 ms
  per psmux call on Windows, blocking terminal echo).
- pane-mode polls every 150 ms; writeHourly writes only changed hour buckets.
- /api/metrics: agenthub_event_loop_delay_seconds{quantile}.

Hooks
- PreToolUse/PostToolUse run with "async": true (settings installer,
  plugin.json, S3 managed settings): Claude Code no longer waits a Node start
  before and after every tool call.

Committed with --no-verify at the owner's request: the pre-commit full server
suite fails on 9 tests that fail identically on 0c2f498 (lane-sync merge: no
git identity on this host; read-pool; resolveHost; codex-usage 1 ms flake).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/__tests__/daily-cost.test.js

@@ -234,6 +234,46 @@ describe("TranscriptCache tokensByHour", () => {
   });
 });
 
+describe("writeHourly skips unchanged hours", () => {
+  const { writeHourly, forgetHourly } = require("../lib/hourly-usage");
+  const bucket = (input) => ({
+    hour: "2026-10-05T08",
+    model: "claude-opus-4-1",
+    speed: "standard",
+    geo: "",
+    tier: "standard",
+    input,
+    output: 0,
+    cacheRead: 0,
+    cacheWrite: 0,
+    cacheWrite1h: 0,
+    webSearch: 0,
+    webFetch: 0,
+    codeExec: 0,
+  });
+  const rows = () =>
+    db
+      .prepare("SELECT input_tokens FROM token_usage_hourly WHERE session_id = 'skip-hourly'")
+      .all()
+      .map((r) => r.input_tokens);
+
+  it("writes a changed hour, skips an unchanged one, and writes again once forgotten", () => {
+    session("skip-hourly", "2026-10-05T08:00:00.000Z");
+    writeHourly("skip-hourly", { a: bucket(5) });
+    assert.deepEqual(rows(), [5]);
+    writeHourly("skip-hourly", { a: bucket(9) });
+    assert.deepEqual(rows(), [9]);
+    // Deleted behind the writer's back: an unchanged bucket is not re-sent…
+    db.prepare("DELETE FROM token_usage_hourly WHERE session_id = 'skip-hourly'").run();
+    writeHourly("skip-hourly", { a: bucket(9) });
+    assert.deepEqual(rows(), []);
+    // …which is why every path that deletes hourly rows forgets them.
+    forgetHourly(["skip-hourly"]);
+    writeHourly("skip-hourly", { a: bucket(9) });
+    assert.deepEqual(rows(), [9]);
+  });
+});
+
 describe("session list cost", () => {
   it("equals the session's own cost, speed and server-tool fees included", async () => {
     session("list-fast", "2026-10-01T00:00:00.000Z");

server/__tests__/install-hooks.test.js

@@ -142,6 +142,19 @@ describe("install-hooks host-only guard (#193)", () => {
   });
 });
 
+describe("async hooks", () => {
+  it("runs only the per-tool-call hooks in the background, in settings and the plugin alike", () => {
+    const { makeHookEntry, ASYNC_HOOKS } = require("../../scripts/install-hooks");
+    const plugin = require("../../.claude-plugin/plugin.json");
+    assert.deepEqual([...ASYNC_HOOKS].sort(), ["PostToolUse", "PreToolUse"]);
+    for (const type of HOOK_TYPES) {
+      const want = ASYNC_HOOKS.has(type) ? true : undefined;
+      assert.equal(makeHookEntry(type).hooks[0].async, want, `settings ${type}`);
+      assert.equal(plugin.hooks[type][0].hooks[0].async, want, `plugin ${type}`);
+    }
+  });
+});
+
 describe("HOOK_TYPES", () => {
   it("is the event list the plugin ships, so the hook status checks every one", () => {
     const exported = require("../../scripts/install-hooks").HOOK_TYPES;

server/__tests__/metrics.test.js

@@ -93,6 +93,7 @@ describe("GET /api/metrics", () => {
       "agenthub_build_info",
       "agenthub_process_uptime_seconds",
       "agenthub_process_resident_memory_bytes",
+      "agenthub_event_loop_delay_seconds",
       "agenthub_sessions",
       "agenthub_agents",
       "agenthub_events_total",

server/__tests__/tmux.test.js

@@ -19,6 +19,21 @@ describe("tmux wrapper", () => {
     assert.equal(tmux.hasSession("agenthub-lane-1"), true);
   });
 
+  it("hasSession answers yes from a fresh list, and asks tmux for anything else", () => {
+    const calls = [];
+    tmux.__setExecImpl((args) => {
+      calls.push(args[0]);
+      if (args[0] === "list-sessions") return "agenthub-lane-1\nagenthub-lane-1-2\n";
+      throw Object.assign(new Error("no session"), { status: 1 });
+    });
+    tmux.listSessions("agenthub-lane-");
+    assert.equal(tmux.hasSession("agenthub-lane-1-2"), true);
+    assert.deepEqual(calls, ["list-sessions"]); // no has-session spawn
+    // Not listed: asked for real (a pane that just died is never trusted).
+    assert.equal(tmux.hasSession("agenthub-lane-1-3"), false);
+    assert.deepEqual(calls, ["list-sessions", "has-session"]);
+  });
+
   it("hasSession returns false when execFileSync throws", () => {
     tmux.__setExecImpl(() => {
       const e = new Error("no such session");