fix(work-beta): thread Execution note into Codex delegation prompt

[davidalee]

Summary

The Codex delegation prompt template silently dropped each plan unit's Execution note field. The standard subagent dispatch path treats it as a first-class signal (ce-work-beta/SKILL.md:172, 208, 270), but plans using test-first or characterization-first lost that signal whenever the executor was Codex via ce-work-beta delegate:codex.

Real usage motivates this — 13 Execution note fields across 7 plans in docs/plans/, including 11 across 5 currently active plans.

Add an <execution_note> tag to the Codex prompt template between <approach> and <constraints>, mirroring the standard path. Population covers single-unit and multi-unit batches, prefixes each entry with U<ID>: when present and Unit <n>: otherwise (no invented IDs), and merges session-level posture requests (per ce-work-beta/SKILL.md:109, which binds them even when the plan has no Execution note) into units lacking their own note.

Honoring guidance:

• test-first — reproduces the full standard guardrails: write failing test first, verify it fails, then implement; no over-implementation beyond the test's behavior slice; skip for trivial renames, pure configuration, or pure styling. Defers to <testing> for scenario completeness.
• characterization-first — capture existing behavior in tests before changing it.
• Any other non-empty note — binding per-unit guidance, but remains subordinate to <constraints> / <testing> / <verify> / <output_contract>. Notes that would reduce validation, coverage, scope discipline, or reporting accuracy are rejected, with conflicts surfaced via the output contract's issues field.

A regression assertion in tests/pipeline-review-contract.test.ts locks <execution_note> presence and both posture strings so the field cannot recur silently. Assertions are quote-style agnostic.

Reviewed by Codex MCP (gpt-5.2 then gpt-5.5) with two adversarial rounds; refinements from both rounds are folded into the single commit.

Stable/beta sync: not propagating — Codex delegation is beta-only; non-beta ce-work has no equivalent workflow file.

Test plan

• bun test — 1340 pass, 0 fail
• bun run release:validate — clean
• Manual smoke: invoke ce-work-beta delegate:codex against a plan with Execution note: test-first on at least one unit, confirm <execution_note> appears in the generated prompt with the posture string and that test-first ordering is honored in the resulting work

[chatgpt-codex-connector]

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