diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index a1c5494..4a30dea 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,18 +12,15 @@ concurrency:
 
 jobs:
   unit-tests:
-    name: Unit tests (server, node ${{ matrix.node-version }})
+    name: Unit tests (server)
     runs-on: ubuntu-latest
-    strategy:
-      matrix:
-        # README's stated minimum, and the version the rest of CI runs on.
-        node-version: ['20', '22']
+    timeout-minutes: 30
     steps:
       - uses: actions/checkout@v5
 
       - uses: actions/setup-node@v5
         with:
-          node-version: ${{ matrix.node-version }}
+          node-version: '22'
           cache: npm
 
       - name: Install dependencies
@@ -32,7 +29,7 @@ jobs:
       - name: Syntax-check all server sources
         run: |
           find server \( -name '*.js' -o -name '*.cjs' \) -not -path '*/node_modules/*' -print0 \
-            | xargs -0 -n1 node --check
+            | xargs -0 -P4 -n1 node --check
 
       - name: Validate sandbox.config.example.json
         run: node -e "JSON.parse(require('fs').readFileSync('server/sandbox.config.example.json', 'utf-8'))"
@@ -43,6 +40,7 @@ jobs:
   client-build:
     name: Client build
     runs-on: ubuntu-latest
+    timeout-minutes: 30
     steps:
       - uses: actions/checkout@v5
 
@@ -60,6 +58,7 @@ jobs:
   e2e:
     name: E2E tests (Playwright)
     runs-on: ubuntu-latest
+    timeout-minutes: 30
     steps:
       - uses: actions/checkout@v5
 
@@ -71,6 +70,12 @@ jobs:
       - name: Install dependencies
         run: npm ci
 
+      - name: Cache Playwright browsers
+        uses: actions/cache@v4
+        with:
+          path: ~/.cache/ms-playwright
+          key: playwright-${{ runner.os }}-${{ hashFiles('package-lock.json') }}
+
       - name: Install Playwright browsers
         run: npx playwright install --with-deps chromium
 
diff --git a/.gitignore b/.gitignore
index 18dc566..c3d4faf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,4 @@ playwright-report/
 .saved-notifications.json
 server/sandbox.config.json
 /tmp/
+.claude/
diff --git a/README.md b/README.md
index de10050..80faadf 100644
--- a/README.md
+++ b/README.md
@@ -19,7 +19,7 @@ VS Code のようにフォルダを選択し、ブラウザ内のターミナル
 
 ## 必要な環境
 
-- Node.js >= 20 / npm >= 9
+- Node.js >= 22 / npm >= 9
 - C++ コンパイラ（node-pty のビルドに必要。Arch: `base-devel`、Ubuntu: `build-essential`）
 - [Claude Code CLI](https://docs.anthropic.com/en/docs/claude-code) — このプロジェクトの主対象。既定で起動するエージェント。
 - [opencode](https://opencode.ai/) — 任意。入っていれば起動時にアプリとして選べます (下記「起動」参照)。入れずに opencode を選んだ場合、ターミナルに `execvp(3) failed` 等のエラーが表示され起動に失敗します。
diff --git a/server/ws/sessionManager.js b/server/ws/sessionManager.js
index 57a94db..3cfc3e0 100644
--- a/server/ws/sessionManager.js
+++ b/server/ws/sessionManager.js
@@ -321,6 +321,7 @@ export function createSession({ cwd, cols, rows, claudeSessionId, shell, sandbox
     startedClaudeSessionId: claudeSessionId || null,
     scheduleId: null, // key into the module-level `schedules` map, if any
     pendingInjection: null, // { text, at } — scheduled prompt awaiting a freshly-resumed session
+    pendingInjectionTimer: null, // RESUME_INJECT_FALLBACK_MS safety net; cleared on teardown
     // Lightweight virtual screen (see screenModel.js): fed every output
     // chunk, exposing the current visible screen and a change counter so
     // read_output can tell "spinner still drawing" from "static screen".
@@ -375,6 +376,10 @@ export function createSession({ cwd, cols, rows, claudeSessionId, shell, sandbox
         if (session.pendingInjection) {
           const inj = session.pendingInjection;
           session.pendingInjection = null;
+          if (session.pendingInjectionTimer) {
+            clearTimeout(session.pendingInjectionTimer);
+            session.pendingInjectionTimer = null;
+          }
           const delivered = injectIntoLiveSession(session, inj.text);
           notifyFired(session, { at: inj.at, text: inj.text }, delivered);
         }
@@ -478,7 +483,7 @@ export function createSession({ cwd, cols, rows, claudeSessionId, shell, sandbox
       }));
     }
 
-    if (!session.socket) {
+    if (!session.socket && sessions.has(session.id)) {
       startTimeout(session, SESSION_EXITED_TIMEOUT_MS);
     }
   });
@@ -794,10 +799,13 @@ async function fireSchedule(scheduleId) {
   session.pendingInjection = { text: entry.text, at: entry.at };
   // Safety net: deliver even if the session never emits an idle gap (e.g. a
   // plain shell). The idle path normally fires first for Claude sessions.
-  setTimeout(() => {
+  // Tracked on the session so a destroyed one doesn't keep a dead timer
+  // armed (it no-ops, but holds the event loop in tests and lingers in prod).
+  session.pendingInjectionTimer = setTimeout(() => {
     if (session.exited || !session.pendingInjection) return;
     const inj = session.pendingInjection;
     session.pendingInjection = null;
+    session.pendingInjectionTimer = null;
     const delivered = injectIntoLiveSession(session, inj.text);
     notifyFired(session, inj, delivered);
   }, RESUME_INJECT_FALLBACK_MS);
@@ -977,6 +985,11 @@ export function destroySession(id, { keepSchedule = true } = {}) {
     session.idleTimer = null;
   }
 
+  if (session.pendingInjectionTimer) {
+    clearTimeout(session.pendingInjectionTimer);
+    session.pendingInjectionTimer = null;
+  }
+
   // By default the scheduled prompt outlives the session (disconnect / idle
   // timeout / shutdown) and auto-resumes at fire time. Only an explicit
   // user-initiated teardown cancels it.
@@ -994,6 +1007,16 @@ export function destroySession(id, { keepSchedule = true } = {}) {
     }
   }
 
+  // Force-close the pty master read stream. kill() alone only signals the
+  // child; if a grandchild still holds the slave fd (or the child lingers),
+  // the master never sees EOF and the read stream keeps the event loop
+  // alive indefinitely (hanging test runners and lingering handles in prod).
+  try {
+    session.ptyProcess.destroy();
+  } catch {
+    // already torn down
+  }
+
   // Remove the sandbox's unique rootlesskit state dir. The --unshare-pid tree is
   // torn down by the kill above (kernel reaps dockerd with the namespace); this
   // just clears the leftover socket dir under /run. Best effort — the dir is
diff --git a/server/ws/sessionManager.test.js b/server/ws/sessionManager.test.js
index 17bcf80..0bcf74e 100644
--- a/server/ws/sessionManager.test.js
+++ b/server/ws/sessionManager.test.js
@@ -65,6 +65,10 @@ before(async () => {
 
 after(() => {
   try { rmSync(runtimeDir, { recursive: true, force: true }); } catch { /* ignore */ }
+  // Release the exited-session retention timers (30s cleanup) and any
+  // pending schedule/fallback timers the tests armed, so the runner process
+  // exits promptly instead of waiting out the production retention period.
+  sessionManager.destroyAllSessions();
 });
 
 test('savedSessionPublic preserves group membership (restart filter keeps working)', () => {