docs(metrics): catalogue the DSX leak-alert counter

[chet]

This is the documentation half of #3742.

Add carbide_dsx_exchange_consumer_alerts_detected_total to the core metrics catalogue with the counter kind and HELP text declared by LeakAlertDetected. The catalogue accepts future rows, so this can land before the Event migration without weakening check-metric-docs.

Related issues

• This supports Finish coherent DSX consumer message Events #3733
• Code change: refactor(dsx): emit queue drops, deduplications, and leak alerts #3742
• Part of Unify logging and metrics behind a single instrumentation standard #3169

Type of Change

• Add - New feature or capability
• Change - Changes in existing functionality
• Fix - Bug fixes
• Remove - Removed features or deprecated functionality
• Internal - Internal changes (refactoring, tests, docs, etc.)

Breaking Changes

• This PR contains breaking changes

Testing

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed
• No testing required (docs, internal refactor, etc.)

Verified with:

• cargo xtask check-metric-docs
• cargo make format-nightly
• git diff --check

Additional Notes

This docs PR should merge before #3742. The code PR can then update from main and satisfy the metric-catalogue gate without including a docs/ change.

[coderabbitai]

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• docs/observability/core_metrics.md

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Summary by CodeRabbit

• Documentation
  • Added documentation for the leak alerts detected metric, including its counter type and meaning.

Walkthrough

The NICo core metrics documentation adds the carbide_dsx_exchange_consumer_alerts_detected_total counter and describes its leak-alert detection count.

Changes

Core metrics documentation

Layer / File(s)	Summary
Document leak-alert counter docs/observability/core_metrics.md	Adds the carbide_dsx_exchange_consumer_alerts_detected_total counter and documents that it counts detected leak alerts.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Possibly related PRs

• NVIDIA/infra-controller#3742: Introduces the LeakAlertDetected event that emits the documented alerts-detected counter.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title is concise and accurately summarizes the new DSX leak-alert counter documentation entry.
Description check	✅ Passed	The description is clearly aligned with the docs-only metric catalogue update and its purpose.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[github-actions]

🌿 Preview your docs: https://nvidia-preview-pull-request-3765.docs.buildwithfern.com/infra-controller

[chet]

@coderabbitai full_review, thanks!

[coderabbitai]

@chet: Starting a fresh, comprehensive review of the PR. 🐇

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