docs(mcp): refresh metadata transport comments

[Q00]

Summary\n\n- Updates stale comments that still said FastMCP metadata is dropped.\n- Clarifies that meta is now preserved while content JSON remains a bridge compatibility surface.\n\n## Changes\n\n- Refreshes comments in subagent and evaluation handler paths.\n\n## Notes\n\nFollow-up for the non-blocking documentation item on #1210.

[ouroboros-agent]

Review — ouroboros-agent[bot]

Verdict: APPROVE

Metadata

| Field | Value |
|### Recovery Notes
First recoverable review artifact generated from codex analysis log.

---|---|
| PR | #1224 |
| HEAD checked | d5da3782da0616362a17f6945bf641dfadea8484 |
| Request ID | req_1779704770_17 |
| Review record | 4b09cb61-3438-4d50-b594-feea50bb8acc |

What Improved

• Clarifies subagent dispatch documentation now that FastMCP preserves meta, while retaining content JSON as the compatibility surface for bridge consumers.

Issue Requirements

Requirement	Status
No linked issue requirement captured	N/A

Prior Findings Status

No prior ouroboros-agent[bot] review content was provided in /tmp/pr_prior_bot_reviews_1224.md; no prior blockers to maintain or withdraw.

Blockers

No in-scope blocking findings remained after policy filtering.

Follow-up Findings

#	File:Line	Priority	Confidence	Suggestion
-	-	-	-	None.

Non-blocking Suggestions

| - | - | - | None. |

Test Coverage Notes

• Reviewed changed files and surrounding adapter/tests: src/ouroboros/mcp/server/adapter.py, tests/unit/mcp/server/test_adapter.py, tests/unit/mcp/tools/test_subagent.py, and lateral inline fallback tests.
• Attempted focused pytest run, but pytest is not installed in this environment (/bin/bash: pytest: command not found).

Design Notes

This is a documentation-only change to comments/docstrings around the existing MCP subagent dispatch boundary. Current HEAD evidence shows _to_fastmcp_tool_result() passes _meta=tool_result.meta or None, while build_subagent_result() still emits _subagent in both content JSON and meta.

Design / Roadmap Gate

Affected boundary is MCP tool result transport for subagent dispatch. The PR does not alter runtime behavior, persistence, replay, or plugin dispatch logic. Compatibility remains intact because content JSON still carries _subagent for bridge clients, and structured clients can use preserved meta.

Directional Notes

Maintainer memory around docs drift shaped the review focus: I checked that the new “meta is preserved” wording matches current runtime adapter behavior and tests, rather than accepting the comment change at face value.

Test Coverage

• Reviewed changed files and surrounding adapter/tests: src/ouroboros/mcp/server/adapter.py, tests/unit/mcp/server/test_adapter.py, tests/unit/mcp/tools/test_subagent.py, and lateral inline fallback tests.
• Attempted focused pytest run, but pytest is not installed in this environment (/bin/bash: pytest: command not found).

Merge Recommendation

Approve. No blocking runtime, contract, or documentation drift issue was found in the changed boundary; test execution was limited only by missing local pytest.

Review-Metadata:
verdict: APPROVE
head_sha: d5da378
request_id: req_1779704770_17
review_profile: memory-aware-zero-trust-v2
advisory_memory_only: true

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Reviewed by ouroboros-agent[bot] via Codex deep analysis