oracle-gemini

name	oracle-gemini
description	This skill should be used when the user asks to "use Gemini", "ask Gemini", "consult Gemini", "Gemini review", "use Gemini for planning", "ask Gemini to review", "get Gemini's opinion", "what does Gemini think", "second opinion from Gemini", mentions using Gemini as an oracle for planning or code review. NOT for implementation tasks.

Gemini Oracle

Use Google Gemini CLI as a planning oracle and code reviewer. Gemini provides analysis and recommendations; Claude synthesizes and presents to the user.

Critical: This skill is for planning and review ONLY. Never use Gemini to implement changes.

Prerequisites

Before invoking Gemini, validate availability:

~/.claude/skills/oracle-gemini/scripts/check-gemini.sh

If the script exits non-zero, display the error message and stop. Do not proceed without Gemini CLI.

Configuration Defaults

Setting	Default	User Override
Model	gemini-2.5-pro	"use flash"
Sandbox	--sandbox	Not overridable (safety)
Timeout	5 minutes minimum	Based on complexity
Output	text	"use json output"

Timeout Guidelines

When invoking gemini via the Bash tool, always set an appropriate timeout:

• Minimum: 5 minutes (300000ms) for any Gemini operation
• Simple queries (single file review, focused question): 5 minutes (300000ms)
• Moderate complexity (multi-file review, feature planning): 10 minutes (600000ms)
• High complexity (architecture analysis, large codebase planning): 15 minutes (900000ms)

Model Selection

Choose model based on task requirements:

Model	Best For	Speed
gemini-2.5-pro	Complex analysis, architecture, comprehensive review	Slower
gemini-2.5-flash	Quick feedback, single-file review, rapid iteration	Fastest

Selection heuristics:

• gemini-2.5-pro: Task involves multiple files, requires deep analysis, or architectural thinking
• gemini-2.5-flash: Simple queries, single file review, or when speed is prioritized

For detailed model capabilities, consult references/gemini-flags.md.

Workflow

1. Validate Prerequisites

Run the check script. On failure, report the installation instructions and abort.

2. Determine Mode

• Planning mode: User wants architecture, implementation approach, or design decisions
• Review mode: User wants code analysis, bug detection, or improvement suggestions

3. Construct Prompt

Build a focused prompt for Gemini based on mode:

Planning prompt template:

Analyze this codebase and provide a detailed implementation plan for: [user request]

Focus on:
- Architecture decisions and trade-offs
- Files to create or modify
- Implementation sequence
- Potential risks or blockers

Do NOT implement anything. Provide analysis and recommendations only.

Review prompt template:

Review the following code for:
- Bugs and logic errors
- Security vulnerabilities
- Performance issues
- Code quality and maintainability
- Adherence to best practices

[code or file paths]

Provide specific, actionable feedback with file locations and line references.

4. Select Model and Execute Gemini

Before executing, assess task complexity to select appropriate model:

1. Count files involved in the query
2. Evaluate scope (single module vs cross-cutting)
3. Consider depth (surface review vs architectural analysis)

Use positional prompt syntax (Gemini CLI does NOT support HEREDOC/stdin). Always use the Bash tool's timeout parameter (minimum 300000ms / 5 minutes).

For short prompts, pass directly as a positional argument:

# Short prompt - direct positional argument
gemini -m gemini-2.5-pro --sandbox -o text "Your prompt here" 2>/dev/null

For long prompts, write to a temp file first, then use command substitution:

# Step 1: Generate unique temp file paths and write prompt
GEMINI_PROMPT="/tmp/gemini-${RANDOM}${RANDOM}.txt"
GEMINI_OUTPUT="/tmp/gemini-${RANDOM}${RANDOM}.txt"
cat > "$GEMINI_PROMPT" <<'EOF'
[constructed prompt with code context]
EOF

# Step 2: Execute Gemini with prompt from file
# Bash tool timeout: 300000-900000ms based on complexity
gemini \
  -m "${MODEL:-gemini-2.5-pro}" \
  --sandbox \
  -o text \
  "$(cat "$GEMINI_PROMPT")" \
  2>/dev/null > "$GEMINI_OUTPUT"

Important flags:

• -m: Model selection (gemini-2.5-pro or gemini-2.5-flash)
• --sandbox: Prevents any file modifications (non-negotiable)
• -o text: Plain text output (use json if user requests structured output)
• 2>/dev/null: Suppresses error messages and stderr noise

Bash tool timeout: Estimate based on task complexity (see Timeout Guidelines above). Never use the default 2-minute timeout for Gemini operations.

5. Present Gemini Output

Read the analysis from the temp file and display to the user with clear attribution:

cat "$GEMINI_OUTPUT"

Format the output with clear attribution:

## Gemini Analysis

[Gemini output from /tmp/gemini-analysis.txt]

---
Model: gemini-2.5-pro

For very large outputs (>5000 lines), summarize key sections rather than displaying everything.

6. Synthesize and Plan

After presenting Gemini output:

1. Synthesize key insights from Gemini analysis
2. Identify actionable items and critical decisions
3. If Gemini's analysis presents multiple viable approaches or significant trade-offs, consider using AskUserQuestion to clarify user preferences before finalizing the plan
4. Write a structured plan to ~/.claude/plans/[plan-name].md
5. Call ExitPlanMode to present the plan for user approval

When to use AskUserQuestion:

• Gemini proposes multiple architectures with different trade-offs
• Technology or library choices need user input
• Scope decisions (minimal vs comprehensive) are ambiguous

Skip clarification when:

• Gemini's recommendations are clear and unambiguous
• User's original request already specified preferences
• Only one viable approach exists

Error Handling

Error	Response
Gemini not installed	Show installation instructions from check script
Gemini timeout	Inform user, suggest simpler query or use flash model
API rate limit	Wait and retry, or inform user of limit
Empty response	Retry once, then report failure

Usage Examples

Planning Request

User: "Ask Gemini to plan how to add authentication to this app"

1. Validate Gemini CLI available
2. Gather relevant codebase context
3. Assess complexity → auth spans multiple modules → use gemini-2.5-pro
4. Construct planning prompt with auth requirements
5. Execute Gemini with gemini-2.5-pro model
6. Present Gemini's architecture recommendations
7. Synthesize into Claude plan format
8. Write to ~/.claude/plans/ and call ExitPlanMode

Code Review Request

User: "Have Gemini review the changes in src/auth/"

1. Validate Gemini CLI available
2. Read files in src/auth/ directory
3. Assess complexity → single directory, focused review → use gemini-2.5-flash for speed
4. Construct review prompt with file contents
5. Execute Gemini review
6. Present findings with file/line references
7. Summarize critical issues and recommendations

Model Override Request

User: "Ask Gemini with flash model to review this function"

1. Validate Gemini CLI available
2. Read the target function
3. User explicitly requested flash model → use gemini-2.5-flash
4. Construct focused review prompt
5. Execute Gemini with flash model
6. Present quick feedback

Additional Resources

Reference Files

• references/gemini-flags.md - Complete model and flag documentation

Scripts

• scripts/check-gemini.sh - Prerequisite validation (run before any Gemini command)