test: Remove manual transactions around MCP spans from the stdio transport

[alexander-alderman-webb]

Description

Issues

Reminders

• Please add tests to validate your changes, and lint your code using uv run ruff.
• Add GH Issue ID & Linear ID (if applicable)
• PR title should use conventional commit style (feat:, fix:, ref:, meta:)
• For external contributors: CONTRIBUTING.md, Sentry SDK development docs, Discord community

[github-actions]

Codecov Results 📊

✅ 98557 passed | ❌ 1 failed | ⏭️ 6756 skipped | Total: 105314 | Pass Rate: 93.58% | Execution Time: 356m 1s

📊 Comparison with Base Branch

Metric	Change
Total Tests	—
Passed Tests	📉 -1
Failed Tests	📈 +1
Skipped Tests	—

➕ New Tests (1)

View new tests

• test_continuous_profiler_auto_start_and_stop_sampled_span_streaming[experiment-gevent]
  • File: tests.profiler.test_continuous_profiler
  • Status: ❌ Failing

❌ Failed Tests

test_continuous_profiler_auto_start_and_stop_sampled_span_streaming[experiment-gevent]

File: tests.profiler.test_continuous_profiler
Suite: py3.6-gevent
Error: AssertionError: profiler should not be running assert '70522d25f80b4602bb784b9fea70df01' is None + where '70522d25f80b4602bb784b9fea70df01' = get_profiler_id()

Stack Trace

tests/profiler/test_continuous_profiler.py:896: in test_continuous_profiler_auto_start_and_stop_sampled_span_streaming
    assert get_profiler_id() is None, "profiler should not be running"
E   AssertionError: profiler should not be running
E   assert '70522d25f80b4602bb784b9fea70df01' is None
E    +  where '70522d25f80b4602bb784b9fea70df01' = get_profiler_id()

✅ Patch coverage is 100.00%. Project has 2506 uncovered lines.
❌ Project coverage is 89.81%. Comparing base (base) to head (head).

Coverage diff

@@            Coverage Diff             @@
##          main       #PR       +/-##
==========================================
- Coverage    89.84%    89.81%    -0.03%
==========================================
  Files          193       193         —
  Lines        24588     24588         —
  Branches      8744      8744         —
==========================================
+ Hits         22089     22082        -7
- Misses        2499      2506        +7
- Partials      1400      1400         —

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Generated by Codecov Action

[sentry-warden]

Duplicate assertion in test_tool_handler_error_stdio

The third assertion checking tx["contexts"]["trace"]["status"] is an exact duplicate of the line above it, meaning the original span["tags"]["status"] check was lost during refactoring and nothing new is verified.

Evidence

• In the original code, three distinct properties were asserted: span["data"][...], span["status"], and span["tags"]["status"].
• After the refactor to remove the manual transaction wrapper, the assertions were mapped to tx["contexts"]["trace"].
• assert tx["contexts"]["trace"]["status"] == "internal_error" appears on both lines 657 and 658, making the second one a no-op.
• The duplicate was introduced because the original span["tags"]["status"] assertion was incorrectly replaced, losing its intent.
• The equivalent FastMCP test (test_fastmcp.py lines 598-601) does not contain this duplicate assertion, confirming it is unintentional.

_{Identified by Warden · find-bugs · 2Z9-MNW}

[sentry-warden]

Resource error test checks wrong dict level for MCP_TOOL_RESULT_IS_ERROR

Assertion checks tx['contexts']['trace'] instead of tx['contexts']['trace']['data'], so it never validates the attribute is actually absent.

Evidence

• Old code checked SPANDATA.MCP_TOOL_RESULT_IS_ERROR not in span['data'] where span was the nested MCP span.
• After removing the manual transaction wrapper, the assertion was migrated to tx['contexts']['trace'] but omitted the ['data'] segment.
• In the same file, test_prompt_handler_with_error (line 970) correctly uses tx['contexts']['trace']['data'] for the identical check.
• tx['contexts']['trace'] contains trace metadata keys (op, status, trace_id), not span attributes, so the assertion always trivially passes and cannot catch regressions.

_{Identified by Warden · find-bugs · VX5-C24}