Add feature flag for more lenient overlay resource checks

[henrymercer]

We would like to start rolling out overlay to standard Actions runners. This PR adds a feature flag to lower the disk space requirement to 14 GB, which is small enough to include the set of standard Actions runners.

Based on #3487 to avoid conflicts. We don't plan to roll this out before #3487 is merged.

Risk assessment

For internal use only. Please select the risk level of this change:

• Low risk: Changes are fully under feature flags, or have been fully tested and validated in pre-production environments and are highly observable, or are documentation or test only.

Which use cases does this change impact?

Workflow types:

• Advanced setup - Impacts users who have custom CodeQL workflows.
• Managed - Impacts users with dynamic workflows (Default Setup, CCR, ...).

Products:

• Code Scanning - The changes impact analyses when analysis-kinds: code-scanning.

Environments:

• Dotcom - Impacts CodeQL workflows on github.com and/or GitHub Enterprise Cloud with Data Residency.

How did/will you validate this change?

• Unit tests - I am depending on unit test coverage (i.e. tests in .test.ts files).

If something goes wrong after this change is released, what are the mitigation and rollback strategies?

• Feature flags - All new or changed code paths can be fully disabled with corresponding feature flags.

How will you know if something goes wrong after this change is released?

• Telemetry - I rely on existing telemetry or have made changes to the telemetry.
  • Dashboards - I will watch relevant dashboards for issues after the release. Consider whether this requires this change to be released at a particular time rather than as part of a regular release.
  • Alerts - New or existing monitors will trip if something goes wrong with this change.

Are there any special considerations for merging or releasing this change?

• No special considerations - This change can be merged at any time.

Merge / deployment checklist

• Confirm this change is backwards compatible with existing workflows.
• Consider adding a changelog entry for this change.
• Confirm the readme and docs have been updated if necessary.

[Copilot]

Pull request overview

This PR adds a new feature flag OverlayAnalysisResourceChecksV2 to lower the minimum disk space requirement for overlay analysis from 20 GB to 14 GB, enabling it to run on standard GitHub Actions runners. The change is fully gated behind a feature flag for safe rollout.

Changes:

• Added OverlayAnalysisResourceChecksV2 feature flag with environment variable CODEQL_ACTION_OVERLAY_ANALYSIS_RESOURCE_CHECKS_V2
• Introduced v2 disk space constants (14 GB threshold vs 20 GB for v1)
• Updated runnerSupportsOverlayAnalysis to conditionally use v2 threshold when flag is enabled
• Enhanced logging to show both available and required disk space in error messages

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated no comments.

File	Description
src/feature-flags.ts	Added new OverlayAnalysisResourceChecksV2 feature flag definition and configuration
src/config-utils.ts	Added v2 disk space constants, updated resource check logic to use v2 threshold when flag enabled, improved logging
src/config-utils.test.ts	Added three comprehensive test cases covering v2 resource check scenarios
lib/*.js	Generated JavaScript files reflecting TypeScript changes (auto-generated, not reviewed)

[esbena]

This is a lower threshold than the v1 limit, allowing overlay

• analysis to run on runners with less available disk space

I'm wondering if the naming should reflect that instead. Or do we envision this to be the new default in a moment?

[esbena]

Also, I do dislike the fact that we are adding significant jsdoc to a variable that is used on the line below, which in turn then does not have any jsdoc. But I do see the precedent just above.