fix(mssql): stop capturing a known connection-failure class in validate_credentials

[Gilbert09]

Problem

A customer checking their MSSQL connection (the incremental-fields setup flow) gets reported to error tracking as a bug when SQL Server drops the connection mid-handshake, even though the identical failure is already treated as an expected, non-retryable condition everywhere else.

The error: pymssql.OperationalError carrying DB-Lib 20017 ("Unexpected EOF from the server") paired with DB-Lib 20002 ("Adaptive Server connection failed").

Changes

• validate_credentials keeps its own MSSQLErrors map, separate from get_non_retryable_errors, to turn a driver error into setup-time guidance. It had no entry for "Adaptive Server connection failed", so a credential check hitting it fell through to capture_exception instead of returning the same generic guidance an unmatched error already gets.
• Adds that pattern to MSSQLErrors, mirroring the equivalent entry already in get_non_retryable_errors for the sync path.
• Extracts the generic "Could not connect to MS SQL" fallback string into a _GENERIC_CONNECTION_ERROR constant, reused by the new entry and the two call sites that already returned it. Mechanical.

How did you test this code?

Test rationale: added test_adaptive_server_connection_failed_returns_generic_message_without_capturing, parallel to the existing test_firewall_block_returns_actionable_message_without_capturing. It reproduces the exact DB-Lib 20017/20002 message from the error-tracking issue and asserts validate_credentials returns the generic guidance without calling capture_exception — the regression this PR fixes.

Ran locally: hogli test products/warehouse_sources/backend/temporal/data_imports/sources/mssql/tests/test_mssql.py (67 passed), ruff check/ruff format --check on both changed files, and mypy on source.py — all clean. Not run: a live MSSQL connection, since the failure is driver-level and fully covered by the unit test.

No duplicate: searched open PRs by keyword (mssql, exception type, module path) and the maintainer's full open-PR list (gh pr list --state open --author Gilbert09) — nothing touches this source's validate_credentials path.

Release status

• No feature flag controls this change

Docs update

None — no user-facing behavior or documented workflow changed; this only removes error-tracking noise for an already-classified failure.

🤖 Agent context

Autonomy: Fully autonomous

Agent: Claude Code, Sonnet 5

Triaged from a live error-tracking webhook. Invoked /writing-tests before adding the test case and /writing-pr-descriptions for this body. The only decision point was where to add the suppression: get_non_retryable_errors/get_retryable_errors already covered the sync path, so the gap was specifically validate_credentials's separate MSSQLErrors map, which Postgres and MySQL's equivalent code shows is the intended place to mirror that classification for the setup-time flow.

[trunk-io]

😎 Merged successfully - details.

[parameterai]

Risk: No findings

This PR adds a "Adaptive Server connection failed" entry to the MSSQL source's validate_credentials error map so a known driver-level connect failure returns generic guidance instead of being captured to error tracking, plus extracts the reused message into a constant. The change is confined to fixed-string error mapping; no security-relevant surface is touched and all returned strings are constants, not driver output.

_{Sentinel reviewed 951018f · Review settings}

[stamphog]

Approved.

Contained error-reporting fix with regression coverage; no open substantive review concerns. Credential acceptance, host restrictions, and ingestion behavior remain unchanged.

• Author wrote 100% of the modified lines and has 2 merged PRs in these paths (familiarity STRONG).

Gate mechanics and policy version

Gate		Result
prerequisites	✓	all clear
deny-list	✓	no deny categories matched
size	✓	11L, 1F substantive, 32L/2F incl. docs/generated/snapshots — within ceiling
tier	✓	T1-agent / T1b-small (32L, 2F, single-area, fix)
stamphog 2.4.1		.stamphog/policy.yml @ 951018f · reviewed head 951018f

[github-actions]

🤖 CI report

⚠️ Trunk lane — backend Python lane

This PR is assigned to the backend Python lane. It runs backend Python tests and may merge in parallel with PRs in other lanes.

✅ Duplication (Python) — clean

New Python code duplication introduced by this branch. Fails at 70+ tokens in app code, or 150+ tokens when both copies live in test files. Advisory while the gate proves itself: extract a shared helper instead of copying.

✅ Duplication (TypeScript) — clean

New TypeScript code duplication introduced by this branch. Fails at 70+ tokens in app code, or 150+ tokens when both copies live in test files. Advisory while the gate proves itself: extract a shared helper instead of copying.

⚠️ Backend coverage — 83.0% of changed backend lines covered — 2 uncovered

🧪 Backend test coverage

Patch coverage — changed backend lines (products + core): █████████████████░░░ 83.0% (10 / 12)

File	Patch	Uncovered changed lines
products/warehouse_sources/backend/temporal/data_imports/sources/mssql/source.py	33.3%	382, 391

🤖 Agents: add a test only if an uncovered line exposes a realistic regression that existing tests miss. Otherwise explain why no new test is needed under "How did you test this code?". Gap list: the patch-coverage artifact on this run (gh run download 160518418359574 -n patch-coverage), or the coverage-data block at the end of this comment.

Per-product line coverage (touched products)

Product	Coverage	Lines
demo	███████████░░░░░░░░░ 55.9%	1,508 / 2,700
batch_exports	████████████████░░░░ 80.1%	21,382 / 26,689
engineering_analytics	█████████████████░░░ 84.9%	11,355 / 13,374
mcp_analytics	█████████████████░░░ 85.7%	4,844 / 5,651
warehouse_suggestions	█████████████████░░░ 87.3%	2,252 / 2,580
posthog_ai	██████████████████░░ 87.7%	4,226 / 4,817
notebooks	██████████████████░░ 88.4%	15,201 / 17,196
today	██████████████████░░ 88.6%	2,866 / 3,233
cdp	██████████████████░░ 88.7%	5,081 / 5,729
mcp_registry	██████████████████░░ 89.0%	1,596 / 1,794
product_tours	██████████████████░░ 89.1%	1,337 / 1,500
cohorts	██████████████████░░ 89.6%	8,458 / 9,438
signals	██████████████████░░ 89.8%	67,354 / 75,014
dashboards	██████████████████░░ 89.8%	7,107 / 7,911
data_modeling	██████████████████░░ 90.1%	10,839 / 12,026
tasks	██████████████████░░ 90.6%	80,614 / 89,007
data_warehouse	██████████████████░░ 90.8%	14,831 / 16,339
canvas	██████████████████░░ 90.9%	7,748 / 8,522
exports	██████████████████░░ 91.0%	9,698 / 10,663
business_knowledge	██████████████████░░ 91.0%	8,791 / 9,656
autoresearch	██████████████████░░ 91.1%	10,139 / 11,125
managed_warehouse	██████████████████░░ 91.2%	11,053 / 12,114
error_tracking	██████████████████░░ 91.6%	16,797 / 18,328
wizard	██████████████████░░ 91.8%	6,008 / 6,548
streamlit_apps	██████████████████░░ 91.8%	3,087 / 3,362
stamphog	██████████████████░░ 92.0%	8,242 / 8,963
conversations	██████████████████░░ 92.0%	29,714 / 32,284
early_access_features	███████████████████░ 92.6%	1,339 / 1,446
alerts	███████████████████░ 92.9%	7,246 / 7,797
review_hog	███████████████████░ 93.0%	14,864 / 15,990
surveys	███████████████████░ 93.1%	6,626 / 7,118
web_analytics	███████████████████░ 93.1%	24,096 / 25,877
notifications	███████████████████░ 93.2%	1,152 / 1,236
approvals	███████████████████░ 93.4%	4,526 / 4,848
cross_project_dashboards	███████████████████░ 93.4%	880 / 942
slack_app	███████████████████░ 93.5%	14,854 / 15,882
context_layer	███████████████████░ 93.7%	3,409 / 3,640
marketing_analytics	███████████████████░ 93.8%	20,074 / 21,402
messaging	███████████████████░ 93.8%	4,468 / 4,762
billing_alerts	███████████████████░ 93.9%	2,090 / 2,226
customer_analytics	███████████████████░ 93.9%	26,079 / 27,773
mcp_store	███████████████████░ 93.9%	9,008 / 9,593
experiments	███████████████████░ 94.2%	33,676 / 35,760
ai_observability	███████████████████░ 94.2%	26,434 / 28,069
replay_vision	███████████████████░ 94.3%	29,048 / 30,807
logs	███████████████████░ 94.5%	15,850 / 16,770
actions	███████████████████░ 94.6%	973 / 1,029
endpoints	███████████████████░ 94.8%	9,298 / 9,812
reminders	███████████████████░ 94.8%	760 / 802
growth	███████████████████░ 94.8%	11,268 / 11,880
skills	███████████████████░ 94.9%	7,031 / 7,410
annotations	███████████████████░ 95.0%	816 / 859
tracing	███████████████████░ 95.2%	3,631 / 3,815
data_catalog	███████████████████░ 95.5%	4,419 / 4,628
access_control	███████████████████░ 95.5%	7,779 / 8,143
product_analytics	███████████████████░ 95.7%	28,676 / 29,952
alerts_platform	███████████████████░ 95.8%	5,013 / 5,234
revenue_analytics	███████████████████░ 95.9%	1,878 / 1,959
data_quality	███████████████████░ 95.9%	8,569 / 8,933
warehouse_sources	███████████████████░ 96.4%	453,815 / 470,829
pulse	███████████████████░ 97.4%	2,023 / 2,078
metrics	████████████████████ 97.7%	4,406 / 4,509
analytics_platform	████████████████████ 98.0%	2,775 / 2,833

Report-only. Patch coverage = changed backend lines covered vs origin/master. Sorted lowest first.
Known gaps: lines covered only by Temporal tests show as uncovered; core line numbers may drift if master changed the same file.

[trunk-io]

   

View Full Report ↗︎ ⋅ Docs

[Gilbert09]

/trunk merge

[deployment-status-posthog]

Deploy status

Environment	Status	Deployed At	Workflow
dev	✅ Deployed	2026-10-10 07:53 UTC	Run
prod-us	✅ Deployed	2026-10-10 08:02 UTC	Run
prod-eu	✅ Deployed	2026-10-10 08:03 UTC	Run