D1058 — A PR assigned to its author claims the plan

Decision. For a contributor's PR, plan-gate accepts the approved plan it closes when the plan is assigned to the PR author or the PR is assigned to its author. Both are maintainer acts: only triage rights can set assignees.

Why. GitHub silently ignores an assignment to a user who never commented on the issue. A contributor who opened a PR without first claiming the plan was blocked by a gate that asked for an assignment the maintainer could not make; the PR author, instead, can always be assigned to their own PR. The cost: the plan itself may stay unassigned, so it no longer shows on its own who holds it.

Alternatives rejected. - A maintainer's approving review as the claim: pull_request_review has no _target variant, so on a fork PR it would run the PR's own workflow copy. - A new maintainer label on the PR: one more label to learn for the same act an assignment already expresses. - Asking the contributor to comment first: it is the rule already, and the trap is precisely the PR that arrives without it.

Consequences. plan-gate.yml re-runs on assigned/unassigned of the PR (pinned by internal/repodocs/plan_gate_test.go). The plan-assignment rule of D955 stays the primary path; the PR assignment is the fallback.