chained-pr

## Activation Contract Load this skill when a planned PR may exceed **400 changed lines**, SDD forecasts `400-line budget risk: High` or `Chained PRs recommended: Yes`, or the user asks for chained/stacked PRs, review slices, or reviewer-load control. ## Hard Rules - Split PRs over **400 changed lines** unless a maintainer explicitly accepts `size:exception`. - The budget constrains how work is **sliced**, never the code itself. Never delete comments, blank lines, docs, or tests, and never compress or restyle code, to fit under the budget. - Slicing is bounded: make **one** honest slicing pass. If no cohesive split brings every slice within budget, stop iterating, keep the best cohesive split, and report the final line count with a `size:exception` recommendation. - Keep each PR reviewable in about **≤60 minutes**. - Use one deliverable work unit per PR; keep tests/docs with the unit they verify. - State start, end, prior dependencies, follow-up work, and out-of-scope items in every chained PR. - Every child PR must include a dependency diagram marking the current PR with `📍`. - In Feature Branch Chain, create a draft/no-merge tracker PR; child PR #1 targets the tracker branch, later children target the immediate parent branch. - Treat polluted diffs as base bugs: retarget or rebase until only the current work unit appears. - Do not mix chain strategies after the user chooses one. ## Decision Gates | Condition | Action | |---|---| | PR ≤400 changed lines and focused | K...