Regression: WP Codebox readiness passes with unusable contracts and unhydrated overlays

[chubes4]

Problem

The readiness contract fixed by #1916 regressed. This command returned validated: true:

homeboy agent-task providers --backend=wp-codebox --selector=wordpress.codebox-agent-task-executor --validate-readiness

Three subsequent local Cooks failed before provider execution in two successive preflight states:

1. The adapter could not resolve @automattic/wp-codebox-core/contracts and emitted empty stdout.
2. After injecting the exact installed dist/contracts.js, runtime preparation failed because /Users/chubes/Developer/php-ai-client@custom-provider-auth-live/vendor/autoload.php was missing.

Runs:

• cook-issue-9689-local-1-attempt-1-4f346eef, then cook-issue-9689-local-2-attempt-1-cd9820a1
• cook-issue-2350-local-1-attempt-1-61261416, then cook-issue-2350-local-2-attempt-1-eaaf5e21
• cook-issue-2351-local-1-attempt-1-e7d1d793, then cook-issue-2351-local-2-attempt-1-1548ad07

This is the exact runtime-contract and Composer-overlay readiness class #1916 required preflight to catch.

Expected contract

Provider readiness executes the same canonical contract resolution and overlay dependency checks as the selected executor before returning validated. A validated provider must be able to enter provider execution without additional environment repair.

Acceptance criteria

• Resolve and validate the exact effective contracts module used by executor startup.
• Validate every declared runtime overlay and required dependency entrypoint, including Composer vendor/autoload.php.
• Use identical effective env/path normalization in readiness and execution.
• Return validated: false with exact owner and repair command before any Cook recipe consumes provider budget.
• Add a regression fixture for a valid contracts module plus missing overlay dependencies.
• Add a fixture for a stale configured core module while an alternate installed package exists.
• Prove readiness success followed immediately by executor startup succeeds through the same configuration identity.

Related

• Preflight WP Codebox runtime contract and overlay readiness #1916
• Run Cook verification against an immutable candidate checkout homeboy#9689
• Regression: OpenCode auto-rejects its assigned suffixed Cook scratch workspace #2350
• Codex agent-task executor emits schema-invalid evidence refs without uri #2351

AI assistance

• AI assistance: Yes
• Tool: Homeboy, WP Codebox executor, and OpenCode
• Models: OpenAI GPT-5.6 Sol and Codex GPT-5.5
• Used for: Ran readiness and live Cook preflights, repaired the contracts path, captured the remaining overlay failure, and drafted this regression. Chris reviewed and owns the report.

[chubes4]

Implementation is in draft PR #2354, with generic Homeboy dependency Extra-Chill/homeboy#9700. Integrated negative-to-positive readiness proof passed. The resumed Cook advanced beyond contracts and overlay readiness, then exposed separate provider-plugin entrypoint issue #2355; retries stopped at the failure budget.