💡 Stacked PR Awareness for Review and Dev-Lead Pipelines

[github-actions[bot]]

Summary

Adapt the pr-review pipeline and dev-lead agent to understand GitHub's new Stacked PRs (announced April 2026, preview). When reviewing a stacked PR, include the parent PR's context in the review prompt so the reviewer understands the incremental change. When dev-lead creates related sub-issue PRs from an initiative, create them as a stack rather than independent PRs.

Market Signal

GitHub unveiled Stacked PRs on April 14, 2026, specifically citing the rise of AI-assisted coding tools as the motivation — AI agents generate higher PR volumes that need better review organization. The feature is paired with the gh-stack CLI extension. This is likely to reach GA within 2026 and become a standard workflow pattern for AI-heavy teams. GitHub's blog post states: "The release of Stacked PRs is a response to the rise of AI-assisted coding tools, which have greatly increased the volume and scale of code submissions."

User Signal

• The existing oversized-PR handling (AGENTS.md: >300 changed files triggers truncated review) is a symptom of the problem Stacked PRs solve
• Initiative-driven development (Cross-repo impact-aware review annotations: proactive downstream-breakage detection in the pr-review pipeline #748, 💡 Adversarial Plan-Critic + Structural Gates for the Initiative-Planner (Bob) #593) regularly produces chains of dependent PRs from sub-issues that would benefit from explicit stack relationships
• The pr-review agent currently reviews each PR in isolation, missing cross-PR context that would improve review quality

Technical Opportunity

The pr-review pipeline (scripts/review-one-pr.sh, scripts/engine.sh) already receives PR metadata via the GitHub API. Detecting stack membership requires querying the gh-stack API for the PR's stack position and parent. The review prompt can be enriched with a "Stack Context" section summarizing parent PR changes. The dev-lead's PR creation flow (scripts/dev-lead-fix-issue.sh) can use the gh-stack CLI to create stacked PRs from ordered sub-issues.

Assessment

Dimension	Score	Rationale
Feasibility	med	Depends on preview API stability; graceful degradation needed
Impact	med	Improves review quality for initiative-driven PR chains; positions for GA
Urgency	med	Feature is in preview; early awareness is valuable but not blocking

Adversarial Review

Strongest objection: Stacked PRs are still in private preview — building on a preview feature risks wasted effort if the API changes or the feature is delayed/altered before GA.

Rebuttal: The proposal is intentionally low-investment at this stage: Phase 1 is detection-only (add stack metadata to review context if available, no-op if not). The gh-stack API is stable enough for read operations. The review context enrichment degrades gracefully — if a PR is not part of a stack, nothing changes. Building awareness now positions the pipeline to leverage stacks immediately when GA lands.

Suggested Next Step

Join the Stacked PRs waitlist, evaluate the gh-stack CLI API surface, and prototype a stack-detection script that enriches PR review context with parent PR summaries.