Proof output retention Phase 5: documentation and skill refresh

[tonyketcham]

Summary

Finish the operator-facing README/SKILL refresh once the remaining output-retention phases land.

Source Context

• Cursor cloud-agent follow-up: https://cursor.com/agents/bc-51322132-f3a3-4f80-b0cd-0ed319ccce62
• Implementation PR: docs: plan proof output retention #199
• Proposal artifact: https://github.com/FlatbreadLabs/flatbread/blob/toeknee/proof-output-retention-ce62/docs/proposals/proof-output-retention-plan.md
• Review artifact: https://github.com/FlatbreadLabs/flatbread/blob/toeknee/proof-output-retention-ce62/docs/proposals/proof-output-retention-review.md
• Judge artifact: https://github.com/FlatbreadLabs/flatbread/blob/toeknee/proof-output-retention-ce62/docs/proposals/proof-output-retention-judge.md
• Phase-specific artifact section: https://github.com/FlatbreadLabs/flatbread/blob/toeknee/proof-output-retention-ce62/docs/proposals/proof-output-retention-plan.md#L296-L308

Why This Exists

• PR docs: plan proof output retention #199 pulled forward some documentation updates for Phase 1, but the proposal's full Phase 5 is broader and depends on Phase 2 CLI flags and Phase 4 oracle evidence behavior.
• The docs need to explain where each output surface lives after the whole project completes: execution transcripts, prompt policy, canvas display tails, persisted state, findings sidecars, and oracle evidence logs.
• This issue should stay open until the CLI option table and caveats describe the shipped behavior, not just the Phase 1 carve-out.

Acceptance Criteria

• Add/refresh a Where output lives section in packages/proof/README.md with the operator version of the consumer/source table.
• Refresh .cursor/skills/proof/SKILL.md caveats and CLI tables for Phase 2 flags and --max-in-memory-output-bytes.
• Document oracle stdout/stderr artifact behavior after Phase 4 lands.
• Add a short migration/release-note paragraph explaining the behavior change from silent truncation to explicit display/prompt policies.
• Verify stale execution-plane mentions of STREAM_CAP, 4000, and 2000 are gone except where documenting display caps.

Verification

• pnpm lint
• pnpm verify

Related Phase Issues

• Proof output retention: Phase 0/1 follow-up hardening #200 — Proof output retention: Phase 0/1 follow-up hardening: Proof output retention: Phase 0/1 follow-up hardening #200
• Proof output retention Phase 2: upstream prompt policy and budget preflight #201 — Proof output retention Phase 2: upstream prompt policy and budget preflight: Proof output retention Phase 2: upstream prompt policy and budget preflight #201
• Proof output retention Phase 3: resume, supervisor, and disk ergonomics #202 — Proof output retention Phase 3: resume, supervisor, and disk ergonomics: Proof output retention Phase 3: resume, supervisor, and disk ergonomics #202
• Proof output retention Phase 4: oracle evidence alignment #203 — Proof output retention Phase 4: oracle evidence alignment: Proof output retention Phase 4: oracle evidence alignment #203
• Proof output retention Phase 5: documentation and skill refresh #204 — Proof output retention Phase 5: documentation and skill refresh: Proof output retention Phase 5: documentation and skill refresh #204

Artifact Linkage

This issue is linked back from docs/proposals/proof-output-retention-plan.md and, where relevant, docs/proposals/proof-output-retention-review.md so the repo artifacts and GitHub issues remain navigable in both directions.