Review and optimize Copilot PR reviewer configuration for azure-dev

[kristenwomack]

Goal

Audit and configure the Copilot PR reviewer to get the most value from automated reviews on this repo. PR #7223 showed the reviewer generating false positives due to missing repo context — #7315 / #7316 address one specific case (modern Go patterns), but we should do a broader review.

Areas to investigate

1. Instruction files coverage

• Current state: Only .github/instructions/extensions.instructions.md\ exists (subscription tenant guidance), plus Add Copilot PR review instructions for modern Go 1.26 patterns #7316 (pending, Go patterns)
• Gaps to evaluate:
  • Do we need a top-level .github/copilot-instructions.md\ with repo-wide review guidance (architecture, IoC patterns, error handling conventions)?
  • Should key patterns from \cli/azd/AGENTS.md\ (action-based commands, IoC container, error handling with \ErrorWithSuggestion) be surfaced in instruction files?
  • Are there other language/path-scoped instructions needed (e.g., Bicep templates, TypeScript extensions)?

2. Review behavior tuning

• False positive patterns: Catalog recurring false positives beyond functionapp: handle .funcignore more gracefully #7223 — are there other common categories we should preempt?
• Comment density: Is the reviewer too noisy or too quiet? Should we adjust the review scope (e.g., security-only, bugs-only)?
• Duplicate comments: PR functionapp: handle .funcignore more gracefully #7223 had 4 identical comments for the same issue on different lines — investigate if there's a way to consolidate

3. Repo settings

• Review the repo-level Copilot code review settings (Settings → Copilot → Code review)
• Confirm the reviewer is using the right base branch for instruction file loading
• Check if org-level policies affect behavior

4. Instruction file size budget

• The reviewer reads only the first ~4K characters per instruction file (per GitHub docs)
• Plan the instruction file strategy to stay within limits while covering the most impactful patterns

Success criteria

• Reduced false positive rate on Go PRs
• Key repo conventions (IoC, action pattern, error handling) reflected in reviewer context
• Documented instruction file strategy so the team knows where to add future guidance

References

• PR with false positives: functionapp: handle .funcignore more gracefully #7223
• Existing fix for Go patterns: Add Copilot PR review instructions for modern Go (1.26) patterns #7315 / Add Copilot PR review instructions for modern Go 1.26 patterns #7316
• AGENTS.md: \cli/azd/AGENTS.md\
• GitHub docs on custom instructions: https://docs.github.com/en/copilot/tutorials/use-custom-instructions

[JeffreyCA]

We should also review any stored Copilot Memories and delete ones that are inappropriate, misleading, or incorrect, see https://docs.github.com/en/copilot/how-tos/use-copilot-agents/copilot-memory#viewing-and-deleting-memories

I think only repo owners have access?