Optimize CI linting with incremental scanning on PRs

[Copilot]

CI currently lints the entire repository (~3-4 minutes). For PRs, only changed files need linting.

Changes

• CI workflow: Conditional linting based on event type

  • PRs: golangci-lint run --new-from-rev=origin/${{ github.base_ref }}
  • Main branch: Full repository scan (unchanged)

• Makefile: New golint-incremental target

  • Requires BASE_REF parameter with validation
  • Usable locally: make golint-incremental BASE_REF=origin/main
  • Original golint target unchanged

Expected Impact

• Small PRs: ~30-60s (down from ~3-4min)
• Large PRs: Proportional improvement
• Main branch: No change

All changed files are still linted. No coverage gaps introduced.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[plan] Optimize CI performance with incremental linting</issue_title>
<issue_description>## Objective

Implement incremental linting in CI using --new-from-rev flag to achieve 50-75% faster linting runs.

Context

Currently, the CI runs golangci-lint on the entire repository (~3-4 minutes). By using the --new-from-rev flag, we can lint only changed files, significantly reducing CI time.

Approach

1. Update CI workflow to use --new-from-rev for pull requests
2. Keep full repository scan for main branch merges
3. Test performance improvement
4. Document the optimization in Makefile comments

Files to Modify

• .github/workflows/ci.yml - Update golangci-lint step (lines 418-419)
• Makefile - Consider adding a golint-incremental target

Implementation

# .github/workflows/ci.yml
- name: Run golangci-lint
  run: |
    if [ "${{ github.event_name }}" = "pull_request" ]; then
      # Incremental linting on PRs
      golangci-lint run --new-from-rev=origin/${{ github.base_ref }}
    else
      # Full scan on main branch
      make golint
    fi

Alternative: Add Makefile target

golint-incremental:
	`@if` [ -n "$(BASE_REF)" ]; then \
		golangci-lint run --new-from-rev=$(BASE_REF); \
	else \
		echo "Error: BASE_REF not set. Use: make golint-incremental BASE_REF=origin/main"; \
		exit 1; \
	fi

Acceptance Criteria

• PR builds use incremental linting
• Main branch builds use full linting
• CI time reduced by 50-75% on PRs
• All changed files are still linted
• No regressions slip through
• Performance improvement documented

Testing

1. Create a test PR with small changes
2. Monitor CI execution time
3. Compare with previous full scan times
4. Verify all changed files are checked

Expected Results

• Before: ~3-4 minutes full scan
• After: ~30-60 seconds incremental (on small PRs)
• Large PRs: Still benefit but less dramatic improvement

Notes

This optimization applies only to PRs. Full repository scans on main branch ensure comprehensive coverage.
Related to #7375

AI generated by Plan Command for discussion #7356

Comments on the Issue (you are @copilot in this section)

• Fixes [plan] Optimize CI performance with incremental linting #7380

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