fix(server): comply_test_controller returns dict to fix controller_detected: false

[bokelley]

Closes #314

Root Cause

The JS storyboard runner (@adcp/sdk) detects the test controller by calling comply_test_controller(scenario='list_scenarios') and checking the response shape. Its detectController function:

const data = result.data;
if (data.success && data.scenarios) {
    return { detected: true, scenarios };
}
return { detected: false };

Previously, comply_test_controller returned json.dumps(result) — a string. FastMCP wraps string-returning tools as structuredContent: {result: "<json string>"}. The runner's unwrapProtocolResponse extracts that as data = {result: "<string>"}, so data.success and data.scenarios are both undefined → controller_detected: false.

Returning the result dict directly causes FastMCP to emit the fields at the top level (structuredContent: {success: true, scenarios: [...]} or via content[0].text). Either path gives the runner data.success = true and data.scenarios = [...] → controller_detected: true.

Confirmed locally: before the fix, the live MCP response was:

"structuredContent": {"result": "{\"success\": true, \"scenarios\": [...]}"}

After the fix:

"structuredContent": {"success": true, "scenarios": ["force_creative_status", ...]}

What Changed

• src/adcp/server/test_controller.py: comply_test_controller closure in register_test_controller changed from -> str + json.dumps(result) to -> dict[str, Any] returning the result directly. The json import is still live (used for the 256 KB payload size check in _handle_test_controller).
• tests/test_test_controller_context.py: removed the json.loads() call in the one test that was calling tool.fn directly; added a regression test that calls fn(scenario='list_scenarios') through the FastMCP registration path and asserts the result is a dict (not a string).

What Tested

• pytest tests/test_test_controller_context.py tests/test_force_create_media_buy_arm_and_force_task_completion.py tests/test_server_dx.py — 75 passed
• pytest tests/ (full suite, excluding pre-existing TLS conformance failure unrelated to this change) — 2312 passed, 0 new failures
• ruff check src/ — passed
• Live MCP wire test: tools/call comply_test_controller scenario=list_scenarios confirmed structuredContent now contains the parsed dict

Pre-PR review:

• code-reviewer: approved — no blockers; flagged missing regression test (now added), nit on fn_metadata comment
• dx-expert: approved — no blockers; clarified that detection works via the text-content fallback path when FastMCP omits structuredContent for dict returns; all four backward-compat questions resolved (no breaking callers, json import remains live, no guide update needed)

Triage-managed PR. This bot does not currently iterate on
review comments or PR conversation threads (only on the source
issue). To unblock:

• Push fixup commits directly: gh pr checkout <num> →
  fix → push.
• Or re-trigger: comment /triage execute on the source
  issue.

See adcp#3121
for context.

Session: https://claude.ai/code/session_01LuThNVrmmHfVvPbfrbWsvy

---

Generated by Claude Code