fix(tests): restore SDK tracer after full_stack fixture teardown

[syf2211]

Summary

The full_stack integration fixture rebinds agent_mod._tracer to a fixture-local TracerProvider but never restored the original tracer after shutdown. Later tests in the same pytest process (notably tests/unit/test_ping.py) then routed spans through a shut-down provider, causing four ping tests to fail when tests/integration/ ran before tests/unit/.

Save and restore the module tracer in teardown, matching the pattern already used in tests/agents/test_record_outcome.py.

Related issue

Closes #581

Checklist

• Tests pass (pytest tests/integration/test_full_pipeline.py tests/unit/test_ping.py — 21 passed; issue reproduction command now green)
• Lint clean on changed file (ruff check tests/integration/test_full_pipeline.py — only pre-existing unused-import warnings in file header)
• Type check clean (mypy tokenjam/)
• CLAUDE.md updated (if architecture changed) — N/A
• Test spans use tests/factories.py (not raw NormalizedSpan) — N/A
• Requested @anilmurty as reviewer

Tests

• pytest tests/integration/test_full_pipeline.py tests/unit/test_ping.py — 21 passed (was 4 failed before fix)
• pytest tests/unit/ tests/synthetic/ tests/agents/ tests/integration/ — 4340 passed, 5 failed (pre-existing unrelated failures in test_backfill_progress.py, test_quickstart.py, test_sdk_config_discovery.py)

Notes

Reviewed with composer-2.5: APPROVE. Minimal three-line fix; teardown order (provider.shutdown() then restore) is correct.

[greptile-apps]

Greptile Summary

Restores the SDK module tracer after the full_stack integration fixture shuts down its fixture-local tracer provider, preventing state leakage into later tests.

Confidence Score: 5/5

The PR appears safe to merge.

The fixture now restores the shared SDK tracer after shutting down its local provider, addressing the reported cross-test contamination without changing production behavior.

Important Files Changed

Filename	Overview
tests/integration/test_full_pipeline.py	Saves the original module tracer before rebinding it and restores it during fixture teardown; no actionable issues identified.

_{Reviews (1): Last reviewed commit: "fix(tests): restore SDK tracer after ful..." | Re-trigger Greptile}

[anilmurty]

Thanks @syf2211 — this is a clean, correct fix (matches #581 exactly and is Rule #11-compliant: it swaps the module-level _tracer reference rather than re-calling set_tracer_provider). It turns out to be the same fix as #630 (@Axiya3749), filed against the duplicate issue #615, which just merged with a before/after reproduction (4 failures → 0). Closing this as a duplicate so we don't double-apply — genuinely appreciated, and your #633/#634 are in review. The shared bug is fixed on main.