D328 — Feature PRs skip the Windows leg and the decision index; the release PR carries both

Decision. On a feature PR, CI runs test (ubuntu, the full make gate plus the smoke, e2e and install suites), web when the frontend or server changed, and pr-title. test-windows runs on every push to main and on the release-please PR, where it stays a required check. docs/decisions.md's generated index is no longer regenerated in feature PRs: a workflow regenerates it on the release PR after release-please updates it, and only there does CI check that it is current (CARTOGRAPHER_STRICT_DECISION_INDEX). Before merging a batch, the coordinator rebases each PR onto the main that holds the previous merges and runs the full make gate locally.

Why. Landing plans in parallel showed that the slow job and the failing jobs were different problems. test-windows took about eight minutes and was the whole wait of every Go PR, for a class of regression (platform-specific code) that is rare and small. Every failure in the same batch was a conflict between PRs that each passed alone: the committed index went stale with each sibling merge, and two PRs together pushed the tool catalogue past its budget (D285). Re-running CI does not catch either before merging, because GitHub tests each PR's merge ref against the main of that moment. A local gate on the rebased tree does, in about two minutes.

The cost: a Windows-only regression reaches main and is seen right after the merge instead of before it, and a release cannot ship until it is fixed. The decision index on main lags by the decisions added since the last release; the files themselves are always there.

Alternatives rejected. - A merge queue: it tests the combined tree, but it is not available for this repository, and it would re-run the slow Windows leg for every queued PR. - Running Windows only when platform-specific files change: the whole suite runs on Windows precisely because path, lock and process behaviour leak into code that is not in a _windows.go file. - Generating the index outside git (at doc-build time): readers on GitHub lose the browsable list. - Committing the regenerated index to main from CI: main is protected, and a bot with a ruleset bypass is a wider permission than the problem needs.

Consequences. Feature PRs and plan issues never run make decisions-index. The release PR is the full pass: if it fails on Windows, fix that before the release. The changes job no longer decides the Windows leg.