skills/ce-work/references/return-to-caller.md

# Return to Caller

Read this when input triage enters Return-to-Caller Mode, and read it again immediately before returning. Input triage owns and validates the invocation grammar. This file owns the full producer envelope, evidence gate, idempotent recovery, and exclusion of standalone simplify, review, PR, CI, and babysitting work.

In this mode `ce-work` performs implementation and local verification only — including mid-implementation Phase 2 "Simplify as You Go" — then returns a structured summary instead of running the standalone shipping tail.

Return:

- `status`: `complete`, `blocked`, or `failed`
- `plan_path`
- `changed_files`
- `u_ids_attempted`
- `u_ids_completed`
- `verification_results`
- `verification_evidence`: one entry per attempted behavior-bearing unit, plus any non-behavioral unit where tests were intentionally skipped. Each entry states the unit/task, `behavior_changed`, `existing_tests_inspected`, `tests_added_or_changed`, tests used unchanged, red failure or characterization observed when applicable, verification commands/results, and any exception reason. For units executed by subagents, this entry is assembled from each worker's returned evidence, not reconstructed from the diff — the red-before-implementation observation exists only in the worker's report.
- `implementation_engine_binding`: the resolved one-run `mode`, `target`, `model`, and `source`, or `null` when native execution was selected without a binding
- `requested_route` and `actual_route`: target plus harness/intermediary identity, kept separate when fallback or same-family substitution occurred
- `requested_model` and `actual_model`: the request and receipt-attributed served identity (`unverified` when the route supplies no trustworthy receipt)
- `fallback_reason`: `null` when none, otherwise the observed route-unavailable or substitution reason
- `run_id`: durable external run identifier, or `null` for native execution
- `source_kind` and `source_digest`: controller-recorded implementation authority (`plan` plus its digest in Return-to-Caller Mode; standalone bare-prompt runs use `prompt`)
- `unit_receipts`: route, model, detached-process, integration, verification, canonical-commit, and cleanup state for each attempted unit
- `plan_checkpoint`: the disclosed checkpoint commit when the selected plan was the only canonical dirt, otherwise `null`
- `blockers`
- `recovery_path`: preserved owner-checked run/workspace location when recovery remains, otherwise `null`
- `settled_decision_conflicts`: conflicts with `session-settled:`-labeled KTDs or Key Decisions encountered during implementation — each entry names the labeled entry, the evidence, and how it was routed (proceeded-and-flagged vs blocker); empty when none
- `behavior_change`: whether behavior-bearing code changed
- `standalone_shipping_skipped: true`

Return `status: complete` only when behavior-bearing work has verification evidence or a deliberate exception. If a previous return-to-caller run implemented code but omitted evidence, a later same-plan return-to-caller run should use the idempotency check to inspect the existing work, complete the evidence, and return without reimplementing.

Engine selection (`references/execution-engines.md`) still applies in this mode, but only for implementation. Do not emit a copyable goal/workflow prompt — a manual paste step strands the caller; run inline/subagents or return a blocker instead. Any goal/workflow engine used here must not open a PR, run the owner workflow tail, or bypass the caller-owned gates.