Fix HighMemoryUsage alert ratio

[Zhaoziyuan2024]

Summary

Fixes #1.

Fix the HighMemoryUsage Prometheus alert so it divides process RSS by machine memory instead of dividing process_resident_memory_bytes by itself. This also adds a focused validation path that rejects self-dividing alert expressions before dry-run or upload.

Changes

• Updated HighMemoryUsage to use process_resident_memory_bytes / on(instance) group_left machine_memory_bytes > 0.9.
• Aligned the instance:memory_usage:ratio recording rule with the same machine-memory denominator.
• Added alert-rule validation for direct same-metric division.
• Added unittest coverage for the recommended alert rules, the fixed memory alert, and an invalid self-dividing alert expression.
• Added the required diagnostic build JSON and .logd chunks generated from the code commit.

Testing

• python -m unittest discover -v
  • Passes: 4 tests.
• python -m py_compile tools/monitoring_setup.py tests/__init__.py tests/test_monitoring_setup.py
  • Passes.
• python tools/monitoring_setup.py --alerts --dry-run
  • Passes and prints the fixed HighMemoryUsage expression.
• PYTHONIOENCODING=utf-8 python build.py
  • Generates diagnostic/build-fb0df9c3.json and three .logd chunks.
  • Exits 1 in this Windows Codex runtime because the runtime is missing the repo's cross-language build tools: Rust, Go, GCC/G++, CMake, Make, Java, Ruby, Lua, and GHC. The bundled Node runtime also does not include npm, so frontend is recorded as failed in the diagnostic metadata.

Checklist

• Relevant modules affected by these changes build locally
• Tests pass locally
• Diagnostic build log is committed in this PR
• Documentation has been updated, if applicable
• Configuration or schema changes are documented, if applicable
• No generated build artifacts are committed, except the required diagnostic build log
• Changes are scoped to the PR purpose and avoid unrelated cleanup
• Security, privacy, and error-handling implications have been considered

---

• I would like to request that my diagnostic build log is removed before merging

[Zhaoziyuan2024]

/claim #1

Ready for review/merge for bounty #1.

This fixes the HighMemoryUsage alert so it no longer divides process_resident_memory_bytes by itself, aligns the recording rule with the same machine-memory denominator, and adds validation/tests to catch direct same-metric division.

Validation performed:

• python -m unittest discover -v - PASS, 4 tests
• python -m py_compile tools/monitoring_setup.py tests/__init__.py tests/test_monitoring_setup.py - PASS
• python tools/monitoring_setup.py --alerts --dry-run - PASS
• PYTHONIOENCODING=utf-8 python build.py generated diagnostic/build-fb0df9c3.json and the .logd chunks; the build exits 1 in my Windows runtime because required cross-language tools are missing, which is recorded in the diagnostic metadata.