Agent Guardrails Skill

Purpose

Structured checklists that ensure the agent considers all applicable rules before and after writing code. Catches issues that would otherwise only surface during verification.

When to Invoke

• Pre-Flight: At the start of Phase 2 (Implement), before writing any code
• Self-Review: At the end of Phase 2 (Implement), after writing code but before Phase 3/4

Pre-Flight Checklist

Run through this checklist before writing any code:

• Identified all applicable rules from .agents/rules/
• Searched for existing patterns in codebase (Pattern Discovery Protocol from architectural-pattern.md)
• Confirmed project structure alignment (project-structure.md)
• Identified I/O boundaries that need abstraction
• Determined test strategy (unit/integration/E2E)
• Reviewed rule-priority.md for any potential conflicts

If any item cannot be checked, stop and resolve before proceeding.

Post-Implementation Self-Review

Run through this checklist after writing code, before verification:

Security

• No hardcoded secrets or configuration values
• All user input validated at system boundaries
• Parameterized queries (no string concatenation for SQL)

Testability

• All I/O operations behind interfaces/abstractions
• Business logic is pure (no side effects in calculations)
• Dependencies injected, not hardcoded

Observability

• All public operation entry points logged (start/success/failure)
• Structured logging with correlation IDs
• Appropriate log levels (not everything is INFO)

Error Handling

• Error paths handled explicitly (no empty catch blocks)
• Errors provide context (wrapped with additional info)
• Resources cleaned up in error paths (defer/finally)

Testing

• Tests cover happy path
• Tests cover at least 2 error paths
• Tests cover edge cases relevant to the domain
• If I/O adapters were modified: integration tests exist and pass
• If UI was modified: E2E tests exist (or Phase 3.5 is planned)

Consistency

• Follows existing codebase patterns (>80% consistency)
• Naming conventions match the codebase
• File organization matches project-structure.md

Language-Specific Self-Review

After completing the universal checklist above, load the relevant language-specific checklist:

Only load the file for languages you are actively writing. If the file doesn't exist yet, skip — but flag its absence so it can be created.

Rule Compliance

This skill enforces:

• All mandates (always-on rules)
• Architectural Patterns @architectural-pattern.md
• Testing Strategy @testing-strategy.md
• Rule Priority @rule-priority.md