# Retro: focused lane harness projection

- Cycle: `101-focused-lane-harness-projection`
- Shipping branch: `deliver/101-focused-lane-harness-projection`
- Branch HEAD before merge: `f0f4884997c4e165455c7de4f94dedf57ebe04bb`
- Shipped SHA: `1cbc73da083830226c9f3c5dfaae35c3991b046b`
- Trace: `trace-d59d6ce6-5334-4ddb-949f-3c8ba49ce521`
- QA evidence: `.evidence/deliver-101-focused-lane-harness-projection/2026-06-08/`

## Summary

Backlog 101 shipped focused lane harness projection for roster dispatch.
The implementation keeps the provider CLI layer thin: validate a small
`lane_harness.v1` manifest, project a temporary harness root with only the
allowed skills, set child config environment variables, record receipts, and
return control to the lead when projection or provider launch fails.

## What Worked

- The model/provider/manifest guardrails caught a real design risk before
  landing: a manifest `model_override` must match the selected provider roster
  model or one of its configured variants.
- Provider failure is now evidence instead of a composition crash. Claude
  spend-limit failure during the cycle became an explicit `failure_kind`
  design input.
- The operator docs now describe the materialize and dispatch path directly in
  `README.md` and the harness-engineering model/provider reference.

## What Went Poorly

- The first squash attempt conflicted in generated `index.yaml`. Resolution was
  correct but should be expected for Harness Kit shipping work: regenerate with
  `harness-kit-checks generate-index --repo .`, never hand-edit.
- The final docs request arrived after the delivery commit, so documentation
  had to be added as an extra shipping-branch commit before archive and squash.

## Backlog Mutations

None proposed. Backlog 101 was archived as part of the shipped squash.

## Harness Proposals

None proposed. The durable learning from this cycle was already codified in
`README.md`, `skills/harness-engineering/references/model-provider-harness-index.md`,
tests, fixtures, and receipt validation.

## Prompt Debt

None. The user's request was sufficiently specific: ensure documentation and
ship to `master`.
