WP Codebox provider plugin staging assumes directory-named entrypoints

[chubes4]

Problem

A valid provider plugin checkout whose WordPress entrypoint is plugin.php cannot cross the WP Codebox agent-task adapter. The adapter and runtime reduce provider_plugin_paths to strings, derive slugs from directory names, and then require <slug>/<slug>.php before staging.

Current checkout:

/Users/chubes/Developer/ai-provider-for-openai@codex-oauth-provider/plugin.php

Generated recipe entries:

{
  "source": "/Users/chubes/Developer/ai-provider-for-openai@codex-oauth-provider",
  "slug": "ai-provider-for-openai-codex-oauth-provider",
  "pluginFile": "ai-provider-for-openai-codex-oauth-provider/ai-provider-for-openai-codex-oauth-provider.php"
}

A second generated entry uses slug ai-provider-for-openai and guesses ai-provider-for-openai/ai-provider-for-openai.php. Both are invalid; the real entrypoint is plugin.php.

The runner already has providerPluginEntryFile(), which detects a plugin header and falls back to plugin.php, but preparePluginDirectory() independently refuses to stage a source unless ${slug}.php exists. The typed entrypoint is then lost again when provider_plugin_paths is forwarded as strings.

Evidence

• Cook run: cook-issue-9689-local-4-attempt-1-078a1df3
• WP Codebox run: run_2b3c9b8bdafb4fae92bf996336d66f11
• Failure: Recipe validation failed with 4 issues.
• Generated recipe reported missing directory and guessed entrypoints under $.inputs.extra_plugins[1] and [2].
• Source task: Run Cook verification against an immutable candidate checkout homeboy#9689
• Readiness chain repairs: Regression: WP Codebox readiness passes with unusable contracts and unhydrated overlays #2352 / Preflight effective WP Codebox runtime settings #2354 and Run provider-owned readiness against effective configured settings homeboy#9696 / Run provider-owned readiness against effective settings homeboy#9700

Expected contract

Provider plugin materialization preserves a detected or explicitly declared WordPress entrypoint as typed data from Homeboy Extensions through WP Codebox recipe generation. Directory names and branch/worktree suffixes are not treated as plugin entrypoints.

Acceptance criteria

• Detect root plugin headers and plugin.php once, before source staging.
• Stage valid plugin directories regardless of whether ${slug}.php exists.
• Preserve { source, slug, pluginFile, loadAs, activate } through the provider plugin boundary.
• Avoid emitting duplicate extra-plugin entries for the same source.
• WP Codebox recipe validation receives the staged source and exact entrypoint.
• Provider readiness rejects missing source paths or missing declared/detected entrypoints before a Cook consumes provider budget.
• Add a fixture checkout named with a worktree suffix whose only entrypoint is plugin.php.

Upstream direction

If WP Codebox currently accepts only string provider_plugin_paths, add a typed provider-plugin contract upstream rather than synthesizing a duplicate slug-named PHP file in the adapter.

AI assistance

• AI assistance: Yes
• Tool: Homeboy, WP Codebox, and OpenCode
• Model: OpenAI GPT-5.6 Sol
• Used for: Ran the repaired readiness and Cook path, inspected the generated recipe and adapter staging code, and drafted the typed-entrypoint contract. Chris reviewed and owns the report.