chore(scripts): add verify-install-simulation.sh pre-release gate (#1490)

Pre-release regression script that simulates a fresh user receiving
cache 5.6.x and starting Claude Code for the first time. Runs the real
_install_statusline against the in-tree hooks/ source in an isolated
tmpdir, then executes the installed script as a subprocess and asserts
the output is the full status line — not the bare '◕‿◕ CodingBuddy'
fallback face.

Why this complements pytest:
  - The pytest E2E gate runs inside the test runner's process and
    fixtures. This shell script exercises the exact code path a user
    hits, including filesystem layout, chmod, and a fresh subprocess.
  - It can be run by maintainers locally before pushing release
    branches without needing to set up a Python venv with pytest.
  - It is invoked from canary CI in the next commit so PRs cannot
    merge with a broken installer.

Exit codes:
  0 — full status line rendered, all assertions passed
  1 — fallback face detected or required tokens missing
  2 — install crashed before render

Local verification at commit time:
  $ bash packages/claude-code-plugin/scripts/verify-install-simulation.sh
  [verify-install-simulation] PASS: full status line rendered
  exit=0
  Output: '◕‿◕ CB v5.6.1 | Ready 🟢 | $0.42🔥$0.21/m | 2m | 0% | Opus 4.6'

Refs #1490

Author: JeremyDev87

packages/claude-code-plugin/scripts/verify-install-simulation.sh

@@ -0,0 +1,142 @@
+#!/usr/bin/env bash
+# verify-install-simulation.sh — pre-release regression gate for #1490
+#
+# Simulates a fresh user receiving cache 5.6.x and starting Claude Code
+# for the first time. Runs _install_statusline against the real plugin
+# hooks/ directory in an isolated tmpdir, then executes the installed
+# script as a real subprocess and asserts the output is the full status
+# line — not the bare '◕‿◕ CodingBuddy' fallback face.
+#
+# This script complements pytest unit/E2E tests by exercising the
+# exact code path a user hits (including the file system, chmod, and
+# subprocess invocation). Run it manually before pushing release
+# branches and from CI on every PR.
+#
+# Exit codes:
+#   0 — full status line rendered, all assertions passed
+#   1 — fallback face detected or required tokens missing
+#   2 — install crashed before render
+
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PLUGIN_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
+HOOKS_DIR="$PLUGIN_ROOT/hooks"
+
+if [ ! -f "$HOOKS_DIR/codingbuddy-hud.py" ]; then
+  echo "[verify-install-simulation] FAIL: HUD source not found at $HOOKS_DIR/codingbuddy-hud.py" >&2
+  exit 2
+fi
+
+TMPHOME="$(mktemp -d)"
+trap 'rm -rf "$TMPHOME"' EXIT
+
+echo "[verify-install-simulation] simulating user install in $TMPHOME"
+
+PLUGIN_ROOT="$PLUGIN_ROOT" HOOKS_DIR="$HOOKS_DIR" TMPHOME="$TMPHOME" \
+python3 - <<'PYEOF'
+import json
+import os
+import subprocess
+import sys
+from pathlib import Path
+
+plugin_root = os.environ["PLUGIN_ROOT"]
+hooks_dir = os.environ["HOOKS_DIR"]
+tmphome = os.environ["TMPHOME"]
+
+# Make session-start.py importable (hyphenated filename)
+sys.path.insert(0, hooks_dir)
+import importlib.util as importutil
+spec = importutil.spec_from_file_location(
+    "session_start", os.path.join(hooks_dir, "session-start.py")
+)
+session_start = importutil.module_from_spec(spec)
+spec.loader.exec_module(session_start)
+
+# Force the installer to use the in-tree source rather than any cached
+# copy on the developer's machine. This guarantees the script under
+# test is exactly what's about to ship.
+hud_source = Path(hooks_dir) / "codingbuddy-hud.py"
+session_start._find_hud_source = lambda: hud_source
+
+home = Path(tmphome)
+settings_file = home / ".claude" / "settings.json"
+settings_file.parent.mkdir(parents=True, exist_ok=True)
+settings_file.write_text("{}")
+
+# Run the installer the same way session-start hook would
+try:
+    session_start._install_statusline(home, settings_file)
+except Exception as exc:
+    print(f"[verify-install-simulation] FAIL: installer crashed: {exc}", file=sys.stderr)
+    sys.exit(2)
+
+installed_script = home / ".claude" / "hud" / "codingbuddy-hud.py"
+installed_lib = home / ".claude" / "hud" / "lib"
+
+if not installed_script.exists():
+    print("[verify-install-simulation] FAIL: script not installed", file=sys.stderr)
+    sys.exit(2)
+if not installed_lib.is_dir():
+    print("[verify-install-simulation] FAIL: lib/ not synced", file=sys.stderr)
+    sys.exit(1)
+
+# Verify the 12 critical modules are present
+required = [
+    "hud_buddy.py", "hud_cache_savings.py", "hud_context_bar.py",
+    "hud_helpers.py", "hud_layout.py", "hud_rainbow.py",
+    "hud_rate_limits.py", "hud_session.py", "hud_state.py",
+    "hud_velocity.py", "hud_version.py", "tiny_actor_presets.py",
+]
+missing = [m for m in required if not (installed_lib / m).is_file()]
+if missing:
+    print(
+        f"[verify-install-simulation] FAIL: missing lib modules: {missing}",
+        file=sys.stderr,
+    )
+    sys.exit(1)
+
+# Render via subprocess — exactly how Claude Code invokes the statusLine
+payload = json.dumps({
+    "session_id": "verify-install-simulation",
+    "model": {"display_name": "Opus 4.6"},
+    "cost": {"total_cost_usd": 0.42, "total_duration_ms": 120000},
+})
+result = subprocess.run(
+    ["python3", str(installed_script)],
+    input=payload,
+    capture_output=True,
+    text=True,
+    timeout=10,
+)
+out = result.stdout
+print(f"[verify-install-simulation] stdout={out!r}")
+print(f"[verify-install-simulation] stderr={result.stderr!r}")
+
+if result.returncode != 0:
+    print(
+        f"[verify-install-simulation] FAIL: render exited {result.returncode}",
+        file=sys.stderr,
+    )
+    sys.exit(1)
+
+if out.strip() == "\u25d5\u203f\u25d5 CodingBuddy":
+    print(
+        "[verify-install-simulation] FAIL: fallback face only — "
+        "installer did not produce a working HUD (#1490 regression)",
+        file=sys.stderr,
+    )
+    sys.exit(1)
+
+required_tokens = ["CB v", "Opus 4.6", "$0.42"]
+for token in required_tokens:
+    if token not in out:
+        print(
+            f"[verify-install-simulation] FAIL: missing token {token!r} in stdout",
+            file=sys.stderr,
+        )
+        sys.exit(1)
+
+print("[verify-install-simulation] PASS: full status line rendered")
+PYEOF