Capstone: Multi-Agent Dev Pipeline

Build a development pipeline using Antigravity: a code review agent, a test generation agent, and a documentation agent working in parallel on the same codebase. Coordinated through a Project with shared skills and GEMINI.md context. Every piece draws from the five days of the course.

What you'll learn

• Three parallel agents: code review, test generation, and documentation, coordinated through an Antigravity Project
• Shared skill library with PR review, test generation, and API documentation skills
• Scheduled automation runs the pipeline on every PR and every morning

Architecture

The system coordinates three specialized agents through a single project configuration. This diagram maps the automation triggers and agent dependencies.

Prerequisites

Complete before starting:

• Installation & Auth: Gemini CLI or Antigravity CLI installed and authenticated
• GEMINI.md Context: comfortable writing project context files
• Custom Slash Commands: understand how commands and skills work
• Parallel Agents: understand multi-agent coordination
• agentskills.io Standard: can write SKILL.md files

Build it

Phase 1: Create the skill library

Three skills in .gemini/skills/:

# .gemini/skills/pr-review/SKILL.md
---
name: pr-review
description: Reviews pull requests for bugs, security issues, and style problems. Use when asked to review a PR or code changes.
version: 1.0.0
---

## Procedure
1. Read the diff using `git diff origin/main...HEAD`
2. For each changed file, check for:
   - Security vulnerabilities (injection, XSS, hardcoded secrets)
   - Logic errors (off-by-one, null checks, race conditions)
   - Style violations (against the project's GEMINI.md standards)
3. For each issue found, report file, line number, severity, and suggested fix
4. Write findings to .antigravity/shared/review.md

## Verification
Run the project's test suite after applying fixes.

Next, define the test generation skill to automate unit test coverage for new endpoints.

# .gemini/skills/test-gen/SKILL.md
---
name: test-gen
description: Generates tests for changed API endpoints. Use when asked to write tests for new or modified code.
version: 1.0.0
---

## Procedure
1. Read the diff to identify changed API endpoints
2. For each endpoint, generate tests covering:
   - Happy path (valid inputs, expected outputs)
   - Edge cases (empty inputs, boundary values, nulls)
   - Error cases (invalid inputs, missing fields, auth failures)
3. Write tests to src/__tests__/ using vitest
4. Run the test suite and fix any failures

Finally, implement the documentation skill to keep API schemas aligned with code changes.

# .gemini/skills/api-docs/SKILL.md
---
name: api-docs
description: Updates API documentation for changed endpoints. Use when API code changes.
version: 1.0.0
---

## Procedure
1. Read the diff to identify changed API endpoints
2. Update docs/api.yaml in OpenAPI 3.0 format
3. Include request/response schemas for all changed endpoints
4. Add example requests and responses
5. Verify the OpenAPI spec is valid using a schema validator

Phase 2: Create the GEMINI.md

Configure the project context to coordinate the agents. This file sets the boundaries and shared conventions.

# GEMINI.md
## Project: Multi-Agent Dev Pipeline
This project uses parallel agents for automated PR pipelines.

## Agent Coordination
- Code Review Agent: focus on security, correctness, and style
- Test Generation Agent: cover all changed API endpoints
- Documentation Agent: update OpenAPI docs for changed endpoints

## Shared Output
- Review findings: .antigravity/shared/review.md
- Generated tests: src/__tests__/
- Updated docs: docs/api.yaml

## Standards
- Use vitest for testing
- OpenAPI 3.0 for documentation
- Conventional commits for commit messages

Phase 3: Run the pipeline

In Antigravity IDE or CLI, launch three parallel agents:

Agent 1 (Code Review):
Review the current branch for bugs and security issues using the pr-review skill.
Write findings to .antigravity/shared/review.md

Agent 2 (Test Generation):
Generate tests for changed API endpoints using the test-gen skill.
Write tests to src/__tests__/. Run the test suite and fix any failures.

Agent 3 (Documentation):
Update API documentation for changed endpoints using the api-docs skill.
Update docs/api.yaml in OpenAPI 3.0 format.

All three agents run simultaneously. The agent manager shows progress for each. When they complete, review the outputs in .antigravity/shared/review.md, src/__tests__/, and docs/api.yaml.

Phase 4: Schedule the morning summary

/schedule "Every weekday at 9 AM: Review all PRs opened in the last 24 hours. Summarize what was merged, what still needs review, and what's blocked. Post the summary."

What goes wrong

Mistake	How you notice it	The fix
Agents conflict on the same file	Merge conflicts or overwritten changes	Assign non-overlapping file scopes. Review reads; tests write to __tests__/; docs write to docs/
Too many agents overwhelm the system	Agents time out or produce incomplete results	Limit to 3 agents. Use /agents to monitor resource usage
Skill not loading	Agent doesn't follow the skill procedure	Verify the skill file is in .gemini/skills/ with correct YAML frontmatter. Run /skills to list available skills
Scheduled task doesn't fire	No summary at 9 AM	Check /schedules for status. Verify the schedule syntax. Check agent API access

Confirm it worked

1. All three agents complete within 5 minutes
2. Review findings are in .antigravity/shared/review.md with specific file, line, and severity
3. Generated tests are in src/__tests__/ and pass when run
4. API documentation is updated in docs/api.yaml with valid OpenAPI 3.0 schema
5. Morning schedule fires and produces a summary

Module map

Capstone component	Course lesson
Skill library	The agentskills.io Standard
Parallel agents	Parallel Agents
GEMINI.md context	GEMINI.md Context Files
Scheduled automation	Scheduled Messages & Automation
Multi-workspace Projects	Multi-Workspace Projects

Resource links:

• Antigravity: antigravity.google
• Gemini CLI: github.com/google-gemini/gemini-cli
• agentskills.io: agentskills.io