Driver

.claude/rules/agdr-decisions.md calls /decide a HARD STOP before any technical decision — library choice, architecture move, new dependency, infra shape. The Code Reviewer agent post-hoc nudges the author if a PR touches architecture without a linked AgDR. There is no PreToolUse hook. The rule is asymmetric: every other HARD STOP in the ruleset (merge approval, ticket-first, migration-first) is mechanically enforced; this one is not.

Scope

Add .claude/hooks/require-agdr-for-arch-pr.sh, wired to PreToolUse on Bash matching gh pr create ….

The hook:

1. Reads the PR's diff via git diff $(git merge-base HEAD <base>)..HEAD --name-only.

2. Loads a configurable set of arch-change patterns from project config:

   # .claude/project-config.json
   agdr_trigger_paths:
     - "**/domain/**"           # DDD domain layer
     - "**/infrastructure/**"   # infra code in hexagonal layout
     - "**/migrations/**"       # data migrations (handled separately by migration hook too)
     - "infrastructure/**"      # Terraform
     - "template.yaml"          # SAM
     - "**/*.tf"                # Terraform HCL
     - ".github/workflows/**"   # CI
   agdr_trigger_dep_files:
     - "package.json"           # new deps
     - "pyproject.toml"
     - "Cargo.toml"
     - "go.mod"
     - "Gemfile"

3. If any changed file matches agdr_trigger_paths, OR any dep-file is modified in a way that adds a dependency, require the PR body to contain a reference matching AgDR-\d+-[a-z0-9-]+.

4. For dep files: parse the diff to detect additions in the dependency sections (don't fire on version bumps — those are a separate /audit-deps concern).

5. On fail: exit 2 with a message naming the triggering file(s) and the skill to invoke (/decide).

6. Skip condition: body contains <!-- agdr: not-applicable --> (rare — e.g. a PR that renames a dependency without a decision change).

Acceptance Criteria

• Hook fires only when the diff touches a trigger path or adds a dependency.
• Hook blocks when no AgDR- reference is in the body.
• Hook passes silently when there's no trigger (most PRs).
• Skip marker passes with a warning.
• Configurable path list ships with sensible defaults; fork owners extend without framework edits.
• Diff parser distinguishes added deps from version-only bumps (unit-tested).
• Fixtures in .claude/hooks/tests/ cover: domain change, infra change, new dep, version-only bump (no fire), skip marker.
• docs/rule-audit.md entry added.

Risks / Dependencies

• False positive on refactors that move files through a trigger path without introducing a decision. Mitigation: skip marker.
• Diff parsing for package.json dependency additions (not bumps) is non-trivial. Use jq or a tiny diff parser. Cover with tests.
• Shares config with the issue-structure validator (apexyard#107). Land after the config location is decided (apexyard#109).

Glossary