ROADMAP-09 — P1 — DELETE /runs/{run_id} (cascade delete is wired but unreachable) #101

Series: ROADMAP — filed from the 2026-10-27 whole-project assessment · Backlog task: M15-T02 · Priority: P1 · Effort: extra small

Problem

Cascade delete of steps on runs is wired end-to-end (ON DELETE CASCADE, verified by the real-infra tier) but unreachable: there is not a single DELETE route. Operators cannot remove a run's audit trail via the API.

Depends on / pairs with ROADMAP-11 (ownership) so only the owning tenant can delete.

Evidence

• agentkit/db/models.py:61,78 + migration line 45 — cascade wired
• agentkit/api/routes.py — zero DELETE routes

Suggested fix / acceptance criteria

• DELETE /runs/{run_id} → 204 on success, 404 identical to GET semantics
• Ownership-scoped once ROADMAP-11 lands (state the interim rule if filed first)
• Integration tests hermetic + real

Suggested branch / commit

feat/run-delete-endpoint · feat(api): add DELETE /runs/{run_id}