Gemini Skill Guide

When to Use Gemini

WHEN ASKED TO BE ACTIVATED

Code Review

Comprehensive code reviews across multiple files

Plan Review

Analyzing architectural plans, technical specifications, or project roadmaps

Big Context Processing

Tasks requiring >200k tokens of context (entire codebases, documentation sets)
Multi-file Analysis: Understanding relationships and patterns across many files ⚠️ Critical: Background/Non-Interactive Mode Warning NEVER use --approval-mode default in background or non-interactive shells (like Claude Code tool calls). It will hang indefinitely waiting for approval prompts that cannot be provided. For automated/background reviews: ✅ Use --approval-mode yolo for fully automated execution ✅ OR wrap with timeout: timeout 300 gemini ... ❌ NEVER use --approval-mode default without interactive terminal Symptoms of hung Gemini: Process running 20+ minutes with 0% CPU usage No network activity Process state shows 'S' (sleeping) Fix hung process:

Check if hung

ps aux | grep gemini | grep -v grep

Kill if necessary

pkill

-9

-f

"gemini.*gemini-3-pro-preview"

Running a Task

Ask the user (via

AskUserQuestion

) which model to use in a

single prompt

. Available models:

gemini-3-pro-preview

⭐ (flagship model, best for coding & complex reasoning, 35% better at software engineering than 2.5 Pro)

gemini-3-flash

(sub-second latency, distilled from 3 Pro, best for speed-critical tasks)

gemini-2.5-pro

(legacy option, strong all-around performance)

gemini-2.5-flash

(legacy option, cost-efficient with thinking capabilities)

gemini-2.5-flash-lite

(legacy option, fastest processing)

Select the approval mode based on the task:

default

Prompt for approval (⚠️ ONLY for interactive terminal sessions)

auto_edit

Auto-approve edit tools only (for code reviews with suggestions)
yolo: Auto-approve all tools (✅ REQUIRED for background/automated tasks) Assemble the command with appropriate options: -m, --model - Model selection --approval-mode - Control tool approval -y, --yolo - Alternative to --approval-mode yolo -i, --prompt-interactive "prompt" - Execute prompt and continue interactively --include-directories - Additional directories to include in workspace -s, --sandbox - Run in sandbox mode for isolation For background/automated tasks, ALWAYS use --approval-mode yolo or add timeout wrapper. NEVER use default in non-interactive shells. Run the command and capture the output. For background/automated mode:

Recommended: Use yolo for background tasks

gemini -m gemini-3-pro-preview --approval-mode yolo "Review this codebase for security issues"

Or with timeout (5 min limit)

timeout

300

gemini

-m

gemini-3-pro-preview --approval-mode yolo

"Review this codebase"

For interactive sessions with an initial prompt:

gemini

-m

gemini-3-pro-preview

-i

"Review the authentication system"

--approval-mode auto_edit

After Gemini completes

, inform the user: "The Gemini analysis is complete. You can start a new Gemini session for follow-up analysis or continue exploring the findings."

Quick Reference

Use case

Approval mode

Key flags

Background code review

yolo

✅

-m gemini-3-pro-preview --approval-mode yolo

Background analysis

yolo

✅

-m gemini-3-pro-preview --approval-mode yolo

Background with timeout

yolo

✅

timeout 300 gemini -m gemini-3-pro-preview --approval-mode yolo

Interactive code review

default

-m gemini-3-pro-preview --approval-mode default

(interactive terminal only)

Code review with auto-edits

auto_edit

-m gemini-3-pro-preview --approval-mode auto_edit

Automated refactoring

yolo

-m gemini-3-pro-preview --approval-mode yolo

Speed-critical background

yolo

✅

-m gemini-3-flash --approval-mode yolo

Cost-optimized background

yolo

✅

-m gemini-2.5-flash --approval-mode yolo

Multi-directory analysis

yolo

(if background)

--include-directories --include-directories

Interactive with prompt

auto_edit

or

default

-i "prompt" --approval-mode

Model Selection Guide

Model

Best for

Context window

Key features

gemini-3-pro-preview

⭐

Flagship model

Complex reasoning, coding, agentic tasks
1M input / 64k output
Vibe coding, 76.2% SWE-bench, $2-4/M input
gemini-3-flash
Sub-second latency, speed-critical applications
1M input / 64k output
Distilled from 3 Pro, TPU-optimized
gemini-2.5-pro
Legacy: Strong all-around performance
1M input / 65k output
Thinking mode, mature stability
gemini-2.5-flash
Legacy: Cost-efficient, high-volume tasks
1M input / 65k output
Best price ($0.15/M), thinking mode
gemini-2.5-flash-lite
Legacy: Fastest processing, high throughput
1M input / 65k output
Maximum speed, minimal latency
Gemini 3 Advantages: 35% higher accuracy in software engineering, state-of-the-art on SWE-bench (76.2%), GPQA Diamond (91.9%), and WebDev Arena (1487 Elo). Knowledge cutoff: January 2025. Coming Soon : gemini-3-deep-think for ultra-complex reasoning with enhanced thinking capabilities. Common Use Cases Code Review (Background/Automated)

For background execution (Claude Code, CI/CD, etc.)

gemini -m gemini-3-pro-preview --approval-mode yolo \ "Perform a comprehensive code review focusing on: 1. Security vulnerabilities 2. Performance issues 3. Code quality and maintainability 4. Best practices violations"

With timeout safety (5 minutes)

timeout 300 gemini -m gemini-3-pro-preview --approval-mode yolo \ "Perform a comprehensive code review..." Plan Review (Background/Automated)

For background execution

gemini -m gemini-3-pro-preview --approval-mode yolo \ "Review this architectural plan for: 1. Scalability concerns 2. Missing components 3. Integration challenges 4. Alternative approaches" Big Context Analysis (Background/Automated)

For background execution

gemini -m gemini-3-pro-preview --approval-mode yolo \ "Analyze the entire codebase to understand: 1. Overall architecture 2. Key patterns and conventions 3. Potential technical debt 4. Refactoring opportunities" Interactive Code Review (Terminal Only)

ONLY use default mode in interactive terminal

gemini -m gemini-3-pro-preview --approval-mode default \ "Review the authentication flow for security issues" Following Up Gemini CLI sessions are typically one-shot or interactive. Unlike Codex, there's no built-in resume functionality. For follow-up analysis, start a new Gemini session with context from previous findings. When proposing follow-up actions, restate the chosen model and approval mode. Use AskUserQuestion after each Gemini command to confirm next steps or gather clarifications. Error Handling Stop and report failures whenever gemini --version or a Gemini command exits non-zero. Request direction before retrying failed commands. Before using high-impact flags ( --approval-mode yolo , -y , --sandbox ), ask the user for permission using AskUserQuestion unless already granted. When output includes warnings or partial results, summarize them and ask how to adjust using AskUserQuestion . Troubleshooting Hung Gemini Processes Detection

Check for hung processes

ps aux | grep -E "gemini.*gemini-3" | grep -v grep

Look for these symptoms:

- Process running 20+ minutes

- CPU usage at 0%

- Process state 'S' (sleeping)

- No network connections

Diagnosis

Get detailed process info

ps -o pid,etime,pcpu,stat,command -p < PID

Check network activity

lsof -p < PID

2

/dev/null | grep -E "(TCP|ESTABLISHED)" | wc -l

If result is 0, process is hung

Resolution

Kill hung Gemini processes

pkill -9 -f "gemini.*gemini-3-pro-preview"

Or kill specific PID

kill -9 < PID

Verify cleanup

ps

aux

|

grep

gemini

|

grep

-v

grep

Prevention

ALWAYS use

--approval-mode yolo

for background/automated tasks

Add timeout wrapper for safety:

timeout 300 gemini ...

Never use

--approval-mode default

in non-interactive shells

Monitor first run with

ps

to ensure process completes

Tips for Large Context Processing

Be specific

Provide clear, structured prompts for what to analyze

Use include-directories

Explicitly specify all relevant directories

Choose the right model

:

Use

gemini-3-pro-preview

for complex reasoning, coding tasks, and maximum analysis quality (recommended default)

Use

gemini-3-flash

for speed-critical tasks requiring sub-second response times

Use

gemini-2.5-flash

for cost-optimized high-volume processing

Leverage Gemini 3's strengths

35% better at software engineering tasks, exceptional at agentic workflows and vibe coding

Break down complex tasks

Even with large context, structured analysis is more effective
Save findings: Ask Gemini to output structured reports that can be saved for reference CLI Version Requires Gemini CLI v0.16.0 or later for Gemini 3 model support. Check version: gemini --version

安装

Check if hung

Kill if necessary

Recommended: Use yolo for background tasks

Or with timeout (5 min limit)

For background execution (Claude Code, CI/CD, etc.)

With timeout safety (5 minutes)

For background execution

For background execution

ONLY use default mode in interactive terminal

Check for hung processes

Look for these symptoms:

- Process running 20+ minutes

- CPU usage at 0%

- Process state 'S' (sleeping)

- No network connections

Get detailed process info

Check network activity

If result is 0, process is hung

Kill hung Gemini processes

Or kill specific PID

Verify cleanup