---
name: implement
description: 'Implement authorized work and repair understood defects; return derived subject identity and check facts. Triggers: "implement", "implement this bead", "run the experiment". Full plan-to-validation requests route to rpi.'
practices:
- tdd
- refactoring
- small-batch-flow
hexagonal_role: driving-adapter
consumes: []
produces:
- subject-manifest.v1
output_contract: 'content identity, author context ID and check facts through the native handoff; subject-manifest.v1 at the judgment boundary'
context_rel:
- kind: customer-of
  with: plan
skill_api_version: 1
user-invocable: true
metadata:
  graph_root: true
  tier: execution
  dependencies: []
  capabilities: [execute_one_experiment, collect_factual_evidence]
  effects: [modify_declared_subject, derive_subject_manifest]
  canonical_status: canonical
  disposition: keep
---

# Implement

Implement the accepted outcome. Repair ordinary known defects directly. Use the existing
intent; no Plan, Recall or Learn worksheet is owed for a clear edit. Implement
owns source changes and factual checks; the runtime derives identity and receipts.

## Workflow

1. Read intent, acceptance, scope and the RPI [boundaries](../rpi/references/boundaries.md)
   before the first write; reuse contracts already loaded in this context.
   When the caller selected episode tracking, obtain permitted work/source
   references before execution and return observed runtime/context identity at
   startup through the native recording channel. Unknowns and recording failures
   stay explicit; do not invent parentage or a second tracker. The optional
   [session association reference](../cass/references/SESSION_FORMATS.md#work-to-session-associations)
   supplies mechanics for that selected workflow.
2. Find nearby validation scripts and tests that consume the edited paths or
   contract wording. Keep their exact commands and the required integration
   recipe in one short check list in the existing handoff; reuse it, updating
   only when inputs or scope change. Run the smallest applicable check before
   editing and after the change. Behavioral changes preserve RED for
   the expected missing behavior; a pure refactor, relocation or documentation
   change may have an honest green baseline. Avoid building elaborate fixtures
   when an existing test or small discriminating probe answers the question.
3. Make the smallest in-scope change. When repairing discovery or checks,
   preserve the consumer's existing input selection; fixing an error path does
   not authorize a wider scan. Use a negative control when exclusion matters.
   Fix known failures directly and rerun the affected check. A disproved
   assumption may change the approach within accepted scope; use Plan only
   for consequential uncertainty.
4. Use targeted tests and applicable repository lint/static checks before
   broad integration. Read the repository's actual check recipe, including
   instrumentation and environment, rather than reconstructing it from memory.
   Run required full checks at integration, not after each small edit. Reuse
   exact-input receipts only while source, tool and relevant environment match.
   Distinguish repository-mandated hook checks from discretionary repeats;
   neither bypass required hooks nor replay a check just to rename its receipt.
5. Refactor while acceptance remains green. Inspect changed tests, fixtures,
   goldens, tolerances, suppressions and specification text against original
   intent. Mocks, placeholders or weakened oracles cannot substitute for the
   requested behavior.
6. Have the runtime derive actual changed paths and content identity. A delegated
   increment awaiting integration returns an exact commit or runtime-derived
   content digests, author context ID and check facts in the existing handoff.
   The integrating caller derives `subject-manifest.v1` over the complete final
   subject before judgment; an independently judged increment needs its own
   manifest. Do not generate both merely because work was delegated.
   At that boundary, when changed paths affect bound acceptance evidence, run
   `ao provenance evidence-orphans --root <repo-root>` with one `--changed
   <path>` per derived path and retain its actual output. Refresh affected
   bindings after repairs; never invent or suppress the orphan list.
7. Return identity, check commands/results, useful failures and accessible
   evidence references through the native handoff, then stop. Full logs stay
   at their source; do not copy them into another inventory or status document.
   Missing or truncated evidence stays explicit.

## Scope and finish

Report an uncovered live consumer as `file:line` for a caller scope amendment;
continue independent authorized work. Generated companions already included as
scope require no new approval. Acceptance changes always require caller authority.

Specialists advise only. Known defects stay implementation work; a genuine
causal stall follows RPI's at-most-one bounded helper rule. Respect remaining
caller/native bounds and reserve finishing capacity. No retry resets them.

Return facts, not semantic PASS. An implement-only handoff does not authorize
Git, tracker or delivery transitions; existing caller authority remains usable.
A full outcome request uses RPI through fresh final judgment. Success is working
behavior with usable evidence, not volume of logs or process artifacts.