Supersedes #555, which GitHub auto-closed when its base branch (worktree-budget-metering, PR #554) was merged and deleted; the branch is now rebased onto main with the single lease commit.

Summary

Fixes a pre-existing defect surfaced by #554's gate review: the debrief-lease winner scan matched ANY DecisionDebriefRequested marker by terminal_event_id, so RunDebriefer and CautionDrafter, which both subscribe to all four terminal Run events, contended for one lease. Whichever applied second saw the other as the winner and wrote a DebriefConflicted/CautionDraftConflicted audit Decision instead of doing its job, leaving the second-registered agent systematically dead in a full deployment. Every subscriber test drove one agent at a time, so the defect was invisible; the caution_drafter call-site comment claimed an independence the code never implemented.

Fix

Contention is now scoped by agent kind (the design memo's target is multi-agent pollution among agents doing the same job: rainbow-deploy variants of one debriefer, different LLM backends of one drafter):

• DecisionDebriefRequested gains an additive debriefer_kind: str | None payload field; the winner scan filters by it. Kindless legacy markers contend with every kind (wildcard), so pre-scoping streams replay unchanged.
• Same-kind semantics unchanged: variants race on stream version; same-agent retries stay idempotent via the uuid5 event_id.
• The one-shot append became a bounded load-scan-append loop (3 attempts): with kinds independent, another kind's lease landing between load and append is now the common version bump, and it retries instead of degrading to a no-winner loss. Exhaustion keeps the degenerate (False, None) exit. decided_by log values: scan / append / retry_exhaustion.
• Glossary + Run module doc updated; the lease design memo carries an amendment note.

Test plan

• Reproducer: test_apply_coexists_with_run_debriefer_on_same_terminal_event fails on pre-fix code (CautionDrafter wrote CautionDraftConflicted), passes now with both agents writing substantive Decisions.
• Primitive pins: cross-kind independence, legacy-wildcard contention, retry-past-non-competitor, retry exhaustion, plus the retrofitted same-kind suite (18 lease tests).
• Full suites green: unit 12204, integration 1044, contract 3336, architecture 28385; pyright clean; naming review (R1-R6) all pass.

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