DocumentationSpecificationRules

Rules

Rules are durable instructions that guide agent behavior for a project.

APC supports two rule surfaces:

  • AGENTS.md for the root project contract
  • .apc/rules/ for reusable or path-scoped project rules

Root rules

Use AGENTS.md for instructions every compatible agent should see when it enters the repository:

  • security boundaries
  • build and test requirements
  • coding standards
  • repository-wide conventions
  • rules that should apply regardless of file path

This makes AGENTS.md the broad, direct, total project rule surface.

Path-scoped rules

Use .apc/rules/ for rules that should load only for specific parts of the repository or specific tasks.

Recommended file types:

.apc/rules/backend.mdc
.apc/rules/frontend.mdc
.apc/rules/security-review.md

Prefer MDC-style frontmatter when a rule has path scope:

---
description: Backend API rules
globs:
  - "src/api/**/*.ts"
alwaysApply: false
---
 
- Validate request input at the route boundary.
- Keep database writes inside service functions.

Compatible consumers may project .apc/rules/*.mdc into Cursor .cursor/rules/, Claude .claude/rules/, or another runtime-specific rule system. APC remains the project-owned source.

Rules vs skills

Use the smallest surface that matches the intent:

IntentAPC location
Applies to the whole repositoryAGENTS.md
Applies to certain paths or tasks.apc/rules/
Reusable procedure an agent may invoke.apc/skills/
Broad human policyrepository docs

Rules should stay concise, concrete, and reviewable. Avoid dumping long transcripts, model reasoning, or unreviewed generated output into rules.

Future direction

APC rules can evolve without requiring every tool to read .apc/ natively. A runtime may keep its own files for execution, while .apc/rules/ stays the stable project source that prevents duplicated or drifting guidance.

SkillsPlans