Python Architecture Skill

[Python architect persona](../../../.apm/agents/python-architect.agent.md)

When to activate

• Creating new Python modules or packages under src/apm_cli/
• Refactoring class hierarchies or introducing base classes
• Changes that touch 3+ files with shared logic patterns
• Introducing new design patterns (Strategy, Observer, etc.)
• Cross-cutting concerns (logging, auth, error handling)
• Performance-sensitive paths (parallel downloads, large manifests)

Key rules

• Follow existing patterns (BaseIntegrator, CommandLogger, AuthResolver) before inventing new ones
• Prefer composition over deep inheritance
• Push shared logic into base classes, not duplicated across siblings
• One canonical owner per decision: route through the existing authority (targetcatalog, AuthResolver/hostproviders, runtime registry, CommandLogger, CompiledOutputWriter, deployment_ledger, install-outcome, neutral hook IR, BaseIntegrator); extend it, never fork it. Full rule: .apm/instructions/architecture.instructions.md
• Lock every centralization with a dual guardrail: a regression test plus a static check in scripts/lint-architecture-boundaries.sh