fix(test): inspect wp-ai-client prompt slot in refinement context test

[chubes4]

Summary

ImageGenerationPromptRefinementTest::test_refine_prompt_includes_post_context_when_provided was failing on main.

The assertion walked $captured_request['messages'] looking for the user message it had just sent. As of #1784 / #1791, RequestBuilder::wpAiClientPromptContext() lifts the latest user message into wp-ai-client's $request['prompt'] slot and routes earlier turns through with_history(). refine_prompt() only sends a single user message, so it lands in prompt and never appears in messages — the assertion was reading an empty string against 'Article context:'.

This is a test-side staleness, not a production bug. The other test in the same file (test_refine_prompt_uses_custom_style_guide) inspects system messages, which still flow through messages via system_instruction, so that one continued to pass.

Fix

Look at $captured_request['prompt'] first (where the active user message ends up), fall back to user-role messages in history. The assertion stays correct regardless of how many user turns the caller sends.

Test results

homeboy test data-machine --skip-lint:

• Before: 1229 passed, 1 failed (this test), 3 skipped, 1233 total.
• After: 1230 passed, 0 failed, 3 skipped, 1233 total.

AI assistance

• AI assistance: Yes
• Tool(s): OpenCode (openai/gpt-5.5)
• Used for: Diagnosing the test failure against current RequestBuilder behavior, applying the test-side fix, and PR preparation. Chris remains responsible for review and merge.

[homeboy-ci]

Homeboy Results — data-machine

Lint

✅ lint — passed

ℹ️ Full options: homeboy docs commands/lint
Deep dive: homeboy lint data-machine --changed-since b83bb66

Test

✅ test — passed

• 13 passed

ℹ️ Auto-fix lint issues: homeboy refactor data-machine --from lint --write
ℹ️ Collect coverage: homeboy test data-machine --coverage
ℹ️ Save test baseline: homeboy test data-machine --baseline
ℹ️ Pass args to test runner: homeboy test -- [args]
ℹ️ Full options: homeboy docs commands/test
Deep dive: homeboy test data-machine --changed-since b83bb66

Audit

✅ audit — passed

• dead_code — 1 finding(s)
• Total: 1 finding(s)

Deep dive: homeboy audit data-machine --changed-since b83bb66

Tooling versions

• Homeboy CLI: homeboy 0.157.1+1baceb8a
• Extension: wordpress from https://github.com/Extra-Chill/homeboy-extensions
• Extension revision: ebde078
• Action: Extra-Chill/homeboy-action@v2