| name | existing-capability-first |
| description | Use when adding or changing a capability surface such as a public function, API, command, prompt, workflow, schema/helper, policy, or reusable instruction. |
Existing Capability First
Search before inventing. Reuse, extend, replace, or delete existing capability
before adding another home for the same concept.
Purpose: keep systems coherent instead of accumulating parallel surfaces.
Consumer: agents adding or changing reusable behavior, APIs, commands, prompts,
workflows, policies, schemas, or helpers.
Failure consequence: duplicate capability diverges; callers pick different
paths; old bugs survive because the new surface bypasses rather than fixes them.
Falsifier: the change is pure formatting, pure refactor, or test-only work that
does not alter a contract or add a reusable surface.
Trigger
Use when a diff adds or changes:
- public function, class, module, route, command, or tool
- prompt template, skill, workflow, policy, or agent instruction
- database/schema/helper surface
- exported config, integration boundary, or decision rule
Skip when no behavior or contract surface changes.
Search Order
Search in this order, using repository-native tools first:
- Exported names, type names, route names, command names.
- Tool surfaces, prompt templates, skills, workflows, and agent docs.
- Existing helpers, schemas, migrations, fixtures, and policy scripts.
- Tests and regression fixtures.
- ADRs, specs, runbooks, and migration history.
- Stale or deprecated implementations that should be deleted or marked
non-authoritative.
Record search keys and nearest artifact. If none exists, say none plus the
reason existing surfaces cannot satisfy the PDD contract.
Decision
- Equivalent exists: reuse or extend it. Update its purpose/consumer contract if
the contract changes.
- Similar but obsolete exists: replace and delete, or mark non-authoritative with
a removal path.
- None exists: add the smallest new surface and state why reuse would fail.
Do not stop at shallow name search in large repos. Search by failure class,
consumer, and data shape too.
