diff --git a/.github/workflows/install-e2e-run.yml b/.github/workflows/install-e2e-run.yml
index 36553831c0..f45848a5e6 100644
--- a/.github/workflows/install-e2e-run.yml
+++ b/.github/workflows/install-e2e-run.yml
@@ -42,7 +42,7 @@ on:
         required: true
         type: string
       update-method:
-        description: 'How the install updates to HEAD. Supported: hermes-update (the updater), installer-script (re-run the one-liner), installer-script+desktop (re-run with --include-desktop). Declared-but-TODO methods (open-app-update, hermes-desktop-app-update) skip.'
+        description: 'How the install updates to HEAD. Supported: hermes-update (the updater), installer-script (re-run the one-liner), installer-script+desktop (re-run with --include-desktop), hermes-desktop-app-update (launch via hermes desktop under Playwright, click Update now). Declared-but-TODO methods (open-app-update) skip.'
         required: true
         type: string
       install-ref:
@@ -61,10 +61,10 @@ on:
         type: string
         default: ubuntu-latest
       timeout-minutes:
-        description: 'Job timeout. A cold run installs real toolchains twice.'
+        description: 'Job timeout. A cold run installs real toolchains twice, and app-update legs add a full Electron build + launch.'
         required: false
         type: number
-        default: 45
+        default: 75
 
 permissions:
   contents: read
@@ -73,13 +73,14 @@ jobs:
   e2e:
     name: install & update
     # The pairs the driver can run today; anything else is a declared TODO
-    # and natively skips. The +desktop variants also need the starting tag
-    # to ship apps/desktop (the --include-desktop flag shipped with it).
+    # and natively skips. Desktop-surface methods (+desktop installs,
+    # hermes-desktop-app-update) also need the starting tag to ship
+    # apps/desktop (their flags shipped with it).
     if: >-
       (inputs.install-method == 'installer-script'
         || (inputs.install-method == 'installer-script+desktop' && inputs.tag-has-desktop))
       && (contains(fromJSON('["hermes-update", "installer-script"]'), inputs.update-method)
-        || (inputs.update-method == 'installer-script+desktop' && inputs.tag-has-desktop))
+        || (contains(fromJSON('["installer-script+desktop", "hermes-desktop-app-update"]'), inputs.update-method) && inputs.tag-has-desktop))
     runs-on: ${{ inputs.runner }}
     timeout-minutes: ${{ inputs.timeout-minutes }}
 
diff --git a/scripts/launch_capture_probe.sh b/scripts/launch_capture_probe.sh
new file mode 100755
index 0000000000..45dc5ee06f
--- /dev/null
+++ b/scripts/launch_capture_probe.sh
@@ -0,0 +1,80 @@
+#!/usr/bin/env bash
+# Probe-the-probe for launch-capture/sitecustomize.py, no real install needed.
+# Control rows FIRST: without the opt-in env var, and for non-launch argv
+# shapes, subprocess.run must behave untouched. Then treatment rows: both
+# launch shapes must be captured without spawning.
+set -euo pipefail
+CAP_DIR="$(cd "$(dirname "$0")" && pwd)/../tests/install/e2e-assets/launch-capture"
+WORK="$(mktemp -d)"
+trap 'rm -rf "$WORK"' EXIT
+
+run_py() {
+  # $1: with_var (yes/no); rest: python -c payload
+  local with_var="$1"; shift
+  if [ "$with_var" = yes ]; then
+    PYTHONPATH="$CAP_DIR${PYTHONPATH:+:$PYTHONPATH}" \
+      HERMES_E2E_CAPTURE_LAUNCH="$WORK/spec.json" python3 "$@"
+  else
+    PYTHONPATH="$CAP_DIR${PYTHONPATH:+:$PYTHONPATH}" python3 "$@"
+  fi
+}
+
+fail() { echo "PROBE FAILED: $*" >&2; exit 1; }
+
+echo "--- control 1: no env var -> run() untouched, real spawn happens"
+out="$(run_py no -c 'import subprocess; print(subprocess.run(["echo","real-spawn"],capture_output=True,text=True).stdout.strip())')"
+[ "$out" = "real-spawn" ] || fail "control 1: expected real-spawn, got '$out'"
+[ ! -e "$WORK/spec.json" ] || fail "control 1: spec written without opt-in"
+echo "OK"
+
+echo "--- control 2: env var set, NON-launch argv (npm run pack) -> passthrough"
+rm -f "$WORK"/spec.json*
+out="$(run_py yes -c 'import subprocess; r=subprocess.run(["echo","npm-build-ran"],capture_output=True,text=True); print(r.stdout.strip())')"
+[ "$out" = "npm-build-ran" ] || fail "control 2: echo did not run"
+# and an actual npm-shaped BUILD argv (argv[0]=npm but no electron token):
+run_py yes -c 'import subprocess,sys; r=subprocess.run(["npm","run","pack"],capture_output=True); sys.exit(0)' 2>/dev/null || true
+[ ! -e "$WORK/spec.json" ] || fail "control 2: build argv was wrongly captured"
+echo "OK"
+
+echo "--- treatment 1: source shape (npm exec -- electron .) captured, not spawned"
+rm -f "$WORK"/spec.json*
+run_py yes -c '
+import subprocess
+r = subprocess.run(["npm", "exec", "--", "electron", "."], cwd="/tmp", env={"HERMES_DESKTOP_CWD": "/tmp", "PATH": "/usr/bin"})
+assert r.returncode == 0, r
+'
+[ -e "$WORK/spec.json" ] || fail "treatment 1: no spec written"
+[ "$(cat "$WORK/spec.json.captured")" = "source" ] || fail "treatment 1: wrong shape"
+python3 - "$WORK/spec.json" <<'EOF'
+import json, sys
+spec = json.load(open(sys.argv[1]))
+assert spec["argv"] == ["npm", "exec", "--", "electron", "."], spec["argv"]
+assert spec["cwd"] == "/tmp", spec["cwd"]
+assert spec["env"]["HERMES_DESKTOP_CWD"] == "/tmp", "env= kwarg not captured"
+assert spec["matchedShape"] == "source"
+print("spec contents OK")
+EOF
+echo "OK"
+
+echo "--- treatment 2: packaged shape captured, not spawned"
+rm -f "$WORK"/spec.json*
+run_py yes -c '
+import subprocess
+exe = "/x/apps/desktop/release/linux-unpacked/Hermes"
+r = subprocess.run([exe, "--no-sandbox"], cwd="/tmp", env={"PATH": "/usr/bin"})
+assert r.returncode == 0, r   # a real spawn of this path would ENOENT
+'
+[ "$(cat "$WORK/spec.json.captured")" = "packaged" ] || fail "treatment 2: wrong shape"
+echo "OK"
+
+echo "--- treatment 3: windows-style packaged argv matches too"
+rm -f "$WORK"/spec.json*
+run_py yes -c '
+import subprocess
+r = subprocess.run(["C:\\x\\apps\\desktop\\release\\win-unpacked\\Hermes.exe"], env={})
+assert r.returncode == 0
+'
+[ "$(cat "$WORK/spec.json.captured")" = "packaged" ] || fail "treatment 3: wrong shape"
+echo "OK"
+
+echo "ALL PROBES PASSED"
diff --git a/tests/install/README.md b/tests/install/README.md
index e9de9fb35b..54cb7f8957 100644
--- a/tests/install/README.md
+++ b/tests/install/README.md
@@ -54,7 +54,7 @@ A leg can install a release from months back. The driver must not assume that th
 The desktop app has two launch paths, so the matrix has two app-update methods. Both click "Update now" in the running app. They differ in how the app starts:
 
 - `open-app-update`: the app starts from the OS entry point that the install created. On windows these are the Start Menu and Desktop shortcuts to the installed `Hermes.exe`; the desktop installer always creates them. The installer scripts do not create entry points: their opt-in desktop stage (`--include-desktop` / `-IncludeDesktop`) builds the app inside the checkout but does not register it with the OS. So `open-app-update` legs pair with a `desktop-installer` install.
-- `hermes-desktop-app-update`: the app starts with the `hermes desktop` command. Every install method provides this command, on each OS that ships the desktop app. On linux this is the only app surface: no desktop installer and no packaged desktop artifact exist for linux.
+- `hermes-desktop-app-update`: the app starts with the `hermes desktop` command. Every install method provides this command, on each OS that ships the desktop app. On linux this is the only app surface: no desktop installer and no packaged desktop artifact exist for linux. The driver captures the product's own launch call (argv, cwd, environment) with `e2e-assets/launch-capture/sitecustomize.py` and re-executes it under Playwright, which owns the app and clicks the update flow.
 
 ## Skips
 
diff --git a/tests/install/e2e-assets/launch-capture/sitecustomize.py b/tests/install/e2e-assets/launch-capture/sitecustomize.py
new file mode 100644
index 0000000000..bf7b391169
--- /dev/null
+++ b/tests/install/e2e-assets/launch-capture/sitecustomize.py
@@ -0,0 +1,102 @@
+"""Driver-side spawn interception for hermes desktop E2E legs.
+
+The installed ``hermes`` is a venv console script, so its interpreter
+imports ``sitecustomize`` at startup when this directory is on
+``PYTHONPATH``. Behind an explicit env-var opt-in the module wraps
+``subprocess.run`` so the FINAL electron launch call of ``hermes
+desktop`` is captured -- argv, cwd, and the fully-constructed ``env``
+kwarg written to a JSON spec -- and replaced with a fake success instead
+of spawning. Everything before the spawn (build, stamps, integrity gate,
+sandbox fixup) runs for real, in the REAL installed code of whatever
+version is under test; Playwright's ``_electron.launch`` then owns the
+app from spawn using exactly the spec the product would have used.
+
+This ships with the DRIVER, never with the product, so it works
+identically on every sampled OLD ref -- version drift in the launch
+shapes is the matcher's problem, which lives here, next to the driver
+(the same maintenance model as ``installer_supports()``).
+
+Opt-in: ``HERMES_E2E_CAPTURE_LAUNCH=<path>`` -- the spec is written
+there, and the marker file ``<path>.captured`` distinguishes "hermes
+desktop exited 0 and we captured" from "exited 0 without reaching a
+launch" (a version that errors out earlier must FAIL the leg, loudly).
+
+Launch shapes across sampled desktop-era tags (verified against each
+tag's own hermes_cli/main.py):
+
+  v2026.6.5    subprocess.run([npm, "exec", "--", "electron", "."], ...)
+  v0.20.0+     the npm-exec form AND subprocess.run(launch_command, ...)
+               where launch_command[0] is the packaged app executable
+               under apps/desktop/release/
+
+Both go through ``subprocess.run`` with an explicit ``env=`` kwarg. npm
+BUILD calls (``npm run build`` / ``npm run pack``) carry no ``electron``
+token in argv and pass through untouched -- they must run for real.
+"""
+
+import os
+
+_SPEC_PATH = os.environ.get("HERMES_E2E_CAPTURE_LAUNCH")
+
+if _SPEC_PATH:
+    import json
+    import subprocess
+
+    _SPEC: str = _SPEC_PATH
+    _real_run = subprocess.run
+
+    def _basename_noext(token: str) -> str:
+        base = os.path.basename(str(token))
+        for ext in (".exe", ".cmd", ".bat"):
+            if base.lower().endswith(ext):
+                base = base[: -len(ext)]
+        return base.lower()
+
+    def _match_shape(argv: "list[str]") -> str:
+        """Return the launch shape for argv, or '' when it is not a launch."""
+        if not argv:
+            return ""
+        tokens = [str(t) for t in argv]
+        head = _basename_noext(tokens[0])
+        # Source shape: npm/npx invoking electron ("npm exec -- electron .").
+        # Membership, not position: absorb argv drift across versions. Build
+        # calls ("npm run pack") carry no bare "electron" token.
+        if head in ("npm", "npx"):
+            if any(_basename_noext(t) == "electron" for t in tokens[1:]):
+                return "source"
+            return ""
+        # Packaged shape: argv[0] is the packaged app executable under
+        # apps/desktop/release/ (win-unpacked/Hermes.exe, linux-unpacked/...,
+        # mac*/Hermes.app/Contents/MacOS/...).
+        first = tokens[0].replace("\\", "/")
+        if "apps/desktop/release/" in first:
+            return "packaged"
+        return ""
+
+    def _capturing_run(*args, **kwargs):
+        argv = args[0] if args else kwargs.get("args")
+        if not isinstance(argv, (list, tuple)):
+            return _real_run(*args, **kwargs)
+        tokens = [str(t) for t in argv]
+        shape = _match_shape(tokens)
+        if not shape:
+            return _real_run(*args, **kwargs)
+        env = kwargs.get("env")
+        spec = {
+            "argv": tokens,
+            "cwd": str(kwargs.get("cwd") or os.getcwd()),
+            # Capture what the child would ACTUALLY get: the constructed
+            # env= when present, the ambient environment when not.
+            "env": dict(env) if env is not None else dict(os.environ),
+            "matchedShape": shape,
+        }
+        tmp = _SPEC + ".tmp"
+        with open(tmp, "w", encoding="utf-8") as fh:
+            json.dump(spec, fh, indent=2)
+        os.replace(tmp, _SPEC)
+        with open(_SPEC + ".captured", "w", encoding="utf-8") as fh:
+            fh.write(shape)
+        print(f"[e2e launch-capture] captured {shape} launch -> {_SPEC} (not spawning)")
+        return subprocess.CompletedProcess(tokens, 0, stdout=None, stderr=None)
+
+    subprocess.run = _capturing_run
diff --git a/tests/install/e2e-assets/launch-from-spec.mjs b/tests/install/e2e-assets/launch-from-spec.mjs
new file mode 100644
index 0000000000..e203ba5714
--- /dev/null
+++ b/tests/install/e2e-assets/launch-from-spec.mjs
@@ -0,0 +1,175 @@
+// @ts-check
+/**
+ * Launch the Hermes desktop app from a captured launch spec and click the
+ * real update flow: Settings -> About -> "Update now".
+ *
+ * The spec is written by launch-capture/sitecustomize.py at `hermes
+ * desktop`'s own spawn site, so argv, cwd, and the fully-constructed env
+ * are the product's own -- this launcher only translates the npm-exec
+ * source shape into a direct electron binary path (Playwright needs a
+ * real executable, and the electron npm shim would re-spawn out of our
+ * control).
+ *
+ * Usage (from the scratch dir where the driver installed @playwright/test):
+ *   node launch-from-spec.mjs --spec /path/launch-spec.json \
+ *     [--result $HERMES_HOME/.hermes-update-result.json] \
+ *     [--expect-sha <sha> --repo-dir <install dir>] [--no-update]
+ *
+ * --no-update: launch + wait for the window + close. The smoke arm.
+ * Otherwise: click Update now, then poll for completion. Two signals,
+ * either satisfies (poll whichever are given, first hit wins):
+ *   --result      the windows hand-off's result file
+ *                 (HERMES_HOME/.hermes-update-result.json)
+ *   --expect-sha  the installed checkout reaching the expected commit -
+ *                 the source-install signal, where the About pane's update
+ *                 runs `hermes update` and no result file exists.
+ * The Playwright close event is unreliable across the update handoff, so
+ * neither signal is an app event.
+ */
+
+import fs from 'node:fs';
+import path from 'node:path';
+import { execFileSync } from 'node:child_process';
+import { parseArgs } from 'node:util';
+import { _electron } from '@playwright/test';
+
+/**
+ * @typedef {{argv: string[], cwd: string, env: Record<string, string>,
+ *            matchedShape: 'source' | 'packaged'}} LaunchSpec
+ */
+
+/**
+ * Resolve what _electron.launch needs from a captured spec.
+ * @param {LaunchSpec} spec
+ * @returns {{executablePath: string, args: string[], cwd: string,
+ *            env: Record<string, string>}}
+ */
+export function resolveLaunch(spec) {
+  if (spec.matchedShape === 'packaged') {
+    return {
+      executablePath: spec.argv[0],
+      args: spec.argv.slice(1),
+      cwd: spec.cwd,
+      env: spec.env,
+    };
+  }
+  // Source shape: ["npm", "exec", "--", "electron", ".", ...extra] running
+  // in apps/desktop. Electron's real binary lives in the workspace-hoisted
+  // node_modules; `electron/index.js` exports its path but requires the
+  // module -- cheaper here to read the path file it derives from.
+  const desktopDir = spec.cwd;
+  const idx = spec.argv.findIndex((t) => t === 'electron');
+  const extra = idx >= 0 ? spec.argv.slice(idx + 1).filter((t) => t !== '.') : [];
+  const candidates = [
+    path.join(desktopDir, 'node_modules', 'electron'),
+    path.join(desktopDir, '..', '..', 'node_modules', 'electron'),
+  ];
+  for (const moduleDir of candidates) {
+    const pathTxt = path.join(moduleDir, 'path.txt');
+    if (!fs.existsSync(pathTxt)) continue;
+    const rel = fs.readFileSync(pathTxt, 'utf8').trim();
+    const exe = path.join(moduleDir, 'dist', rel);
+    if (fs.existsSync(exe)) {
+      return { executablePath: exe, args: ['.', ...extra], cwd: desktopDir, env: spec.env };
+    }
+  }
+  throw new Error(`no electron binary found under ${candidates.join(' or ')}`);
+}
+
+/** @param {string} msg */
+function log(msg) {
+  console.log(`[launch-from-spec] ${msg}`);
+}
+
+async function main() {
+  const { values } = parseArgs({
+    options: {
+      spec: { type: 'string' },
+      result: { type: 'string' },
+      'expect-sha': { type: 'string' },
+      'repo-dir': { type: 'string' },
+      'no-update': { type: 'boolean', default: false },
+      'timeout-ms': { type: 'string', default: '600000' },
+    },
+  });
+  if (!values.spec) throw new Error('--spec is required');
+  /** @type {LaunchSpec} */
+  const spec = JSON.parse(fs.readFileSync(values.spec, 'utf8'));
+  const launch = resolveLaunch(spec);
+  log(`launching ${launch.executablePath} (shape: ${spec.matchedShape})`);
+
+  const app = await _electron.launch({
+    executablePath: launch.executablePath,
+    args: launch.args,
+    cwd: launch.cwd,
+    env: launch.env,
+  });
+  const window = await app.firstWindow({ timeout: 120_000 });
+  await window.waitForLoadState('domcontentloaded');
+  log(`window up: ${await window.title()}`);
+  await window.screenshot({ path: `${values.spec}.window.png` }).catch(() => {});
+
+  if (values['no-update']) {
+    log('smoke mode: window proven, closing');
+    await app.close().catch(() => {});
+    return;
+  }
+
+  if (!values.result && !(values['expect-sha'] && values['repo-dir'])) {
+    throw new Error('need --result and/or --expect-sha + --repo-dir unless --no-update');
+  }
+  const deadline = Date.now() + Number(values['timeout-ms']);
+
+  // Dismiss the onboarding overlay when present (fresh HERMES_HOME).
+  const skip = window.getByRole('button', { name: /skip|get started|continue/i }).first();
+  if (await skip.isVisible({ timeout: 5_000 }).catch(() => false)) {
+    await skip.click().catch(() => {});
+  }
+
+  // Settings -> About -> Update now. Selectors favor accessible names over
+  // DOM structure so renderer refactors don't break the leg.
+  await window.getByRole('button', { name: /settings/i }).first().click();
+  await window.getByRole('tab', { name: /about/i }).or(
+    window.getByRole('button', { name: /about/i })).first().click();
+  const updateNow = window.getByRole('button', { name: /update now/i }).first();
+  await updateNow.waitFor({ state: 'visible', timeout: 60_000 });
+  await updateNow.click();
+  log('clicked Update now; polling for result file');
+
+  // The app may relaunch/exit during the update; completion signals are
+  // product state, not Playwright events.
+  const resultPath = values.result;
+  const expectSha = values['expect-sha'];
+  const repoDir = values['repo-dir'];
+  /** @returns {string} */
+  const headSha = () => {
+    try {
+      return execFileSync('git', ['-C', /** @type {string} */ (repoDir), 'rev-parse', 'HEAD'], {
+        encoding: 'utf8',
+      }).trim();
+    } catch {
+      return '';
+    }
+  };
+  for (;;) {
+    if (resultPath && fs.existsSync(resultPath)) {
+      log(`update result present: ${fs.readFileSync(resultPath, 'utf8').slice(0, 200)}`);
+      break;
+    }
+    if (expectSha && repoDir && headSha() === expectSha) {
+      log(`checkout reached expected sha ${expectSha}`);
+      break;
+    }
+    if (Date.now() > deadline) {
+      await window.screenshot({ path: `${values.spec}.timeout.png` }).catch(() => {});
+      throw new Error('update completion signal never appeared (result file / expected sha)');
+    }
+    await new Promise((r) => setTimeout(r, 2_000));
+  }
+  await app.close().catch(() => {});
+}
+
+const invoked = process.argv[1] && path.resolve(process.argv[1]) === (await import('node:url')).fileURLToPath(import.meta.url);
+if (invoked) {
+  await main();
+}
diff --git a/tests/install/installer-script-e2e.sh b/tests/install/installer-script-e2e.sh
index d2e1a0a009..bc6078f3be 100755
--- a/tests/install/installer-script-e2e.sh
+++ b/tests/install/installer-script-e2e.sh
@@ -35,6 +35,9 @@
 #   --update-method  hermes-update      `hermes update`
 #                    installer-script   re-run install.sh (HEAD's copy)
 #                    installer-script+desktop  re-run with --include-desktop
+#                    hermes-desktop-app-update  launch the app via `hermes
+#                                       desktop` (spawn captured, Playwright
+#                                       drives it) and click Update now
 #   --install-ref    what to install first; anything git resolves. Default:
 #                    the newest release tag in the checkout.
 #
@@ -65,8 +68,8 @@ case "$INSTALL_METHOD" in
   *) echo "error: --install-method must be installer-script or installer-script+desktop, got '$INSTALL_METHOD'" >&2; exit 1 ;;
 esac
 case "$UPDATE_METHOD" in
-  hermes-update|installer-script|installer-script+desktop) ;;
-  *) echo "error: --update-method must be hermes-update, installer-script or installer-script+desktop, got '$UPDATE_METHOD'" >&2; exit 1 ;;
+  hermes-update|installer-script|installer-script+desktop|hermes-desktop-app-update) ;;
+  *) echo "error: --update-method must be hermes-update, installer-script, installer-script+desktop or hermes-desktop-app-update, got '$UPDATE_METHOD'" >&2; exit 1 ;;
 esac
 
 REPO_ROOT="$(cd "$(dirname "$0")/../.." && pwd)"
@@ -290,6 +293,51 @@ case "$UPDATE_METHOD" in
     run_installer "$HEAD_SHA" head desktop
     assert_desktop_artifact HEAD
     ;;
+  hermes-desktop-app-update)
+    # The real user surface: `hermes desktop` launches the app, the user
+    # clicks Settings -> About -> Update now. Playwright must OWN the spawn
+    # (it needs the inspection pipe), so the driver intercepts the product's
+    # own launch call - argv/cwd/env captured at the spawn site by
+    # e2e-assets/launch-capture/sitecustomize.py - and re-executes it under
+    # _electron.launch. Everything before the spawn (build, stamps, sandbox
+    # fixup) runs for real in the installed code.
+    HERMES="$INSTALL_DIR/venv/bin/hermes"
+    ASSETS="$REPO_ROOT/tests/install/e2e-assets"
+    SPEC="$WORK_ROOT/launch-spec.json"
+
+    step "capturing the hermes desktop launch spec (build runs for real)"
+    rc=0
+    (cd "$INSTALL_DIR" && \
+      PYTHONPATH="$ASSETS/launch-capture${PYTHONPATH:+:$PYTHONPATH}" \
+      HERMES_E2E_CAPTURE_LAUNCH="$SPEC" \
+      "$HERMES" desktop < /dev/null > "$LOG_DIR/desktop-launch-capture.log" 2>&1) || rc=$?
+    log_group "hermes desktop (launch capture) transcript" "$LOG_DIR/desktop-launch-capture.log"
+    [ "$rc" -eq 0 ] || fail "hermes desktop exited $rc during launch capture; transcript above"
+    # Exit 0 without a capture means a version that never reached its
+    # launch - that must fail loudly, not pass as a no-op.
+    [ -f "$SPEC.captured" ] || fail "hermes desktop exited 0 but no launch was captured at $SPEC"
+    ok "captured $(cat "$SPEC.captured") launch spec"
+
+    step "driving the app under Playwright: Settings -> About -> Update now"
+    # Driver tooling comes from the driver: a scratch dir with our own
+    # pinned @playwright/test, never resolved from the installed tree
+    # (older OLD refs predate the dependency; hoisting moves it around).
+    PW_DIR="$WORK_ROOT/playwright"
+    mkdir -p "$PW_DIR"
+    (cd "$PW_DIR" && npm install --no-save --no-audit --no-fund \
+      "@playwright/test@1.58.2" > "$LOG_DIR/playwright-install.log" 2>&1) \
+      || { log_group "playwright install transcript" "$LOG_DIR/playwright-install.log"; fail "playwright install failed"; }
+    cp "$ASSETS/launch-from-spec.mjs" "$PW_DIR/"
+    rc=0
+    (cd "$PW_DIR" && node launch-from-spec.mjs \
+      --spec "$SPEC" \
+      --result "$HERMES_HOME/.hermes-update-result.json" \
+      --expect-sha "$HEAD_SHA" \
+      --repo-dir "$INSTALL_DIR" \
+      > "$LOG_DIR/app-update.log" 2>&1) || rc=$?
+    log_group "app update (Playwright) transcript" "$LOG_DIR/app-update.log"
+    [ "$rc" -eq 0 ] || fail "app-driven update exited $rc; transcript above"
+    ;;
 esac
 assert_checkout "$HEAD_SHA" HEAD
 smoke_desktop head