2830 Gemini Invocation 8f204a18

# Gemini CLI Invocation

## Default Configuration

- Model: `gemini-3-pro-preview`
- Extensions: `code-review`, `gemini-cli-security`

## Key Flags

| Flag | Purpose |
|------|---------|
| `-p <prompt>` | Non-interactive (headless) mode |
| `--yolo` / `-y` | Auto-approve all tool calls |
| `-m <model>` | Model selection |
| `-e <ext>` | Load specific extension(s) |

## Scope-to-Diff Mapping

Gemini does not have built-in scope flags like Codex. Map the
user's scope choice to the correct `git diff` command:

| Scope | Diff command |
|-------|-------------|
| Uncommitted | `git diff HEAD` (captures both staged and unstaged) |
| Branch diff | `git diff <branch>...HEAD` |
| Specific commit | `git diff <sha>~1..<sha>` |

**Important:** For uncommitted scope, use `git diff HEAD` not
bare `git diff`. Bare `git diff` misses staged changes.

## Code Review (General, Performance, Error Handling)

For uncommitted changes, the `/code-review` extension
automatically picks up the working tree diff:

```bash
gemini -p "/code-review" \
  --yolo \
  -e code-review \
  -m gemini-3-pro-preview
```

For branch diffs or specific commits, pipe the diff into a
heredoc-based prompt to avoid shell expansion issues:

```bash
git diff <branch>...HEAD > /tmp/review-diff.txt
cat <<'PROMPT' | gemini -p - \
  -m gemini-3-pro-preview \
  --yolo
Review this diff for code quality issues. <focus prompt>

$(cat /tmp/review-diff.txt)
PROMPT
```

## Security Review

The `/security:analyze` extension is interactive-only, so use
headless mode with a security-focused prompt instead:

```bash
git diff HEAD > /tmp/review-diff.txt
cat <<'PROMPT' | gemini -p - \
  -e gemini-cli-security \
  -m gemini-3-pro-preview \
  --yolo
Analyze this diff for security vulnerabilities, including
injection, auth bypass, data exposure, and input validation
issues. Report each finding with severity, location, and
remediation.

$(cat /tmp/review-diff.txt)
PROMPT
```

When security focus is selected, also run dependency scanning:

```bash
gemini -p "/security:scan-deps" \
  --yolo \
  -e gemini-cli-security \
  -m gemini-3-pro-preview
```

## Adding Project Context

If project context was requested, prepend it to the prompt:

```bash
git diff HEAD > /tmp/review-diff.txt
cat <<'PROMPT' | gemini -p - \
  -m gemini-3-pro-preview \
  --yolo
Project conventions:
---
<CLAUDE.md or AGENTS.md contents>
---

<review instructions and focus>

$(cat /tmp/review-diff.txt)
PROMPT
```

## Error Handling

| Error | Action |
|-------|--------|
| `gemini: command not found` | Tell user: `npm i -g @google/gemini-cli` |
| Extension missing | Tell user: `gemini extensions install <github-url>` |
| `-e security` silently ignored | Use `-e gemini-cli-security` (the actual installed name) |
| Timeout | Inform user, suggest scoping down the diff |

## Extension Install Commands

```bash
gemini extensions install https://github.com/gemini-cli-extensions/code-review
gemini extensions install https://github.com/gemini-cli-extensions/security
```

Note: The security extension installs as `gemini-cli-security`
(not `security`). Always use `-e gemini-cli-security` when
loading it.