feat: report query session closure reasons

[KirillKurdyukov]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 91.30435% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.41%. Comparing base (c1cdcba) to head (75db727).

Files with missing lines	Patch %	Lines
ydb/aio/query/session.py	41.66%	6 Missing and 1 partial ⚠️
ydb/query/session.py	97.95%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #873      +/-   ##
==========================================
+ Coverage   82.33%   82.41%   +0.07%     
==========================================
  Files          99       99              
  Lines       12750    12810      +60     
  Branches     1242     1254      +12     
==========================================
+ Hits        10498    10557      +59     
+ Misses       1798     1797       -1     
- Partials      454      456       +2     

Flag	Coverage Δ
integration	80.29% <91.30%> (+0.05%)	⬆️
unit	48.32% <20.65%> (-0.08%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
ydb/aio/query/base.py	100.00% <100.00%> (+3.12%)	⬆️
ydb/aio/query/pool.py	94.66% <100.00%> (+0.03%)	⬆️
ydb/observability/metrics.py	97.56% <100.00%> (+0.03%)	⬆️
ydb/opentelemetry/metrics_plugin.py	95.55% <ø> (ø)
ydb/query/base.py	95.23% <100.00%> (+0.18%)	⬆️
ydb/query/pool.py	92.50% <100.00%> (+0.04%)	⬆️
ydb/query/session.py	92.51% <97.95%> (+0.67%)	⬆️
ydb/aio/query/session.py	83.90% <41.66%> (-4.85%)	⬇️

... and 2 files with indirect coverage changes

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[robot-vibe-db]

AI Review Summary

Verdict: ✅ No critical issues found

Critical issues

No critical issues found.

Other findings

• Major | Medium: _on_execute_stream_error now closes sessions on Unavailable and SessionExpired, changing prior non-terminal behavior — ydb/query/session.py:222-237
• Minor | Medium: count_open() lacks the lock that count_closed() uses, creating asymmetric thread-safety on the shared _counted flag — ydb/observability/metrics.py:459
• Minor | Low: Normal attach-stream termination now closes the session (reason="attach_closed"), whereas before it only logged and left the session open — ydb/query/session.py:439
• Nit | Medium: pool.stop() calls _session_metrics.count_closed() directly instead of going through _close_session(), briefly decoupling the metric state from the session state — ydb/query/pool.py:329

---

This review was generated automatically. Critical issues require attention; other findings are advisory.
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[robot-vibe-db]

Severity: Minor
Confidence: Medium

count_open() reads and writes _counted without acquiring self._lock, while count_closed() does hold the lock. This creates asymmetric thread-safety on the shared flag.

In the current call ordering this is safe — count_open() runs inside _attach() before the background thread that could call count_closed() is started. However, if the calling pattern ever changes (e.g., a reconnect path that re-opens a session while the old status loop is still draining), the unprotected write in count_open() could race with count_closed().

Consider acquiring self._lock in count_open() as well, for consistency and future-proofing.

[robot-vibe-db]

Full analysis log

Analysis performed by claude, claude-opus-4-6.