Agy

Antigravity CLI Cross-Review

Send Claude-written code to Google Antigravity CLI (agy; Gemini 3 family) for an independent second opinion that may surface missed bugs, security issues, or alternatives.

Same workflow as gemini-cli-review, but launched via CLI binary + PTY wrapper.

Upstream Bug #76 and Workaround

agy -p silently drops stdout or hangs on non-TTY (subprocess / pipe / redirect) (upstream issue #76). Unfixed as of v1.0.2.

Implemented workaround: agy_pty_wrapper.py runs agy in a pseudo-terminal so TTY detection and stdout work. It auto-selects Windows = pywinpty (ConPTY) / Linux and macOS = ptyprocess, using their identical caller API. Windows is verified (OK/PONG in ~30s); Unix is statically reviewed but hardware-untested.

Prerequisites

1. agy binary

agy --version 2>&1 || "$LOCALAPPDATA/agy/bin/agy.exe" --version 2>&1

Automatic resolution: --agy-path first; then Windows: %LOCALAPPDATA%\agy\bin\agy.exe → PATH (shutil.which agy); Linux/macOS: PATH → ~/.local/bin/agy, ~/.antigravity/bin/agy, /usr/local/bin/agy. On POSIX, use --agy-path when agy is off PATH.

2. Authentication (one time only)

agy auth login

Run in PowerShell → log in via browser. Persists afterward.

3. PTY wrapper dependencies (per OS)

# Windows:
python -c "import winpty" 2>&1 || pip install pywinpty
# Linux / macOS:
python -c "import ptyprocess" 2>&1 || pip install ptyprocess

The wrapper imports only the current OS backend: Windows=pywinpty; Linux/macOS=ptyprocess. Missing backends exit 4 with the package name and pip install hint.

Step 1: Determine the Review Target

With an argument (/agy <filepath>):

• Read the specified file

Without an argument (/agy):

• Identify files Claude edited or created this session
• Read them all if multiple (confirm with the user if too many)
• If none can be identified, ask "Please tell me the review target path."

Step 2: Launch agy via the PTY Wrapper

Pass the prompt as an argument. Set the timeout on both the wrapper (--timeout) and Bash (timeout):

python "$HOME/.claude/skills/agy/agy_pty_wrapper.py" \
  "You are an expert code reviewer providing a second opinion on code written by Claude AI. Your goal is to find issues that Claude might have missed and suggest alternative approaches from a fresh perspective.

Review the following code:

<filename>
[filename]
</filename>

<code>
[code content]
</code>

Please evaluate:
1. Bugs and correctness issues (logic errors, edge cases, off-by-one errors)
2. Security vulnerabilities (injection, authentication issues, data exposure)
3. Code quality (readability, maintainability, naming, complexity)
4. Alternative approaches Claude might not have considered

Be concise and direct. Flag only meaningful issues, not minor style nitpicks. If the code looks good, say so." \
  --timeout 180

Also set timeout: 200000 (200s) on the Bash tool.

Prompt argument escaping: For prompts with many double quotes, pass via a heredoc → environment variable:

PROMPT=$(cat <<'EOF'
You are an expert code reviewer...
EOF
)
python "$WRAPPER" "$PROMPT" --timeout 180

Model selection: agy has no -m flag; the model is fixed CLI-side (currently the Gemini 3 family). Unlike gemini-cli-review, it does not switch models by character count.

Step 3: Organize and Display the Results

Parse the wrapper's stdout (ANSI already stripped). Format as:

## Antigravity Cross-Review Results

**Review target:** `<filename>`

### Key Findings
(In order of severity. If none, "No findings")
- **[CRITICAL/HIGH/MEDIUM]** finding

### Suggested Alternative Approaches
(Include if any. Omit if none)
- ...

### Comments from Claude
(Claude's judgment on each finding.
 "Correct, needs fixing", "Not a problem in the current context, because ~", etc.
 Frankly acknowledge oversights.)

Step 4: Guide Toward Fixes

For findings judged "needs fixing":

• Propose "Shall I fix X?"
• After approval, fix via the normal editing flow

Troubleshooting

Symptom	Cause / Fix
Output is just the word Python, exits immediately (no review)	python/python3 is the WindowsApps stub (App Execution Alias), not the real interpreter. Launch the wrapper with python3.13 (or py -3.13); replace python in this SKILL's examples as needed.
wrapper exit 4 + "pywinpty/ptyprocess not installed"	Run the shown pip install <pkg> (Windows=pywinpty / POSIX=ptyprocess)
wrapper exit 3 + "agy executable not found"	Specify --agy-path or check the install (POSIX: verify agy is on PATH)
wrapper exit 2 + empty stdout	agy unresponsive even inside a TTY; likely expired auth — re-run agy auth login
wrapper timeout (exit 2 + "Timeout after")	Huge prompt or upstream outage. Extend --timeout, --print-timeout 5m
Hangs beyond 200 seconds	Bash timeout expired. Keep the wrapper's --timeout below the Bash timeout
Garbled Japanese text	agy's output-side issue (wrapper only strips ANSI). Avoid by adding "Reply in English" to the prompt

Example Output

## Antigravity Cross-Review Results

**Review target:** `src/auth.py`

### Key Findings
- **[HIGH]** `verify_token()` lacks a token expiration check
- **[MEDIUM]** MD5 used for password hashing (bcrypt/argon2 recommended)

### Suggested Alternative Approaches
- `PyJWT.decode()` automatically validates the `exp` claim

### Comments from Claude
The expiration-check finding is correct. An oversight during implementation.
MD5 is intentional for compatibility with the existing system. Consider migrating new passwords to bcrypt.

Shall I fix it? I can add an expiration check to `verify_token()`.

Implementation Files

• agy_pty_wrapper.py — cross-platform PTY wrapper (Windows=pywinpty ConPTY / POSIX=ptyprocess; custom to this skill, harmless even after bug #76 is resolved)