feat: bound autonomous release command runtime (#329)

docs/release-engine-spec.md

@@ -14,13 +14,14 @@ Convert one eligible Gitea issue into a tested, traceable pull request without d
 - Optional explicit issue number; otherwise deterministic queue selection.
 - Coding-agent command, parsed into an argument vector.
 - Test command, parsed into an argument vector.
+- Positive, independent coding-agent and test deadlines plus a termination grace period.
 - Local repository path and durable state-file path.
 
 ## State machine
 
 `discovered → claimed → agent_complete → tests_passed → pushed → pr_opened`
 
-Terminal failure states are `claim_failed`, `agent_failed`, `tests_failed`, and `push_failed`. A rerun resumes from persisted state and never opens a duplicate PR.
+Terminal failure states include `claim_failed`, `agent_failed`, `agent_timed_out`, `tests_failed`, `tests_timed_out`, and `push_failed`. A rerun resumes from persisted state and never opens a duplicate PR.
 
 ## Queue selection
 
@@ -45,6 +46,10 @@ Terminal failure states are `claim_failed`, `agent_failed`, `tests_failed`, and
 - Empty or malformed commands abort before the issue claim.
 - Non-zero coding-agent exit blocks tests and PR creation.
 - Tests run using the configured command; stdout/stderr and exit code become evidence.
+- Coding-agent and test commands each run in a new process session. Their deadlines default to 1800 and 900 seconds, respectively.
+- On expiry, the engine sends `SIGTERM` to the command's entire process group, waits for the termination grace period (5 seconds by default), then sends `SIGKILL` to the group and reaps the command. This prevents descendants from keeping the worker wedged.
+- Deadlines are configured with `--agent-timeout`, `--test-timeout`, and `--termination-grace`, or `RELEASE_AGENT_TIMEOUT`, `RELEASE_TEST_TIMEOUT`, and `RELEASE_TERMINATION_GRACE`. Non-positive values abort before issue discovery or claim.
+- Timeout evidence is bounded in durable state. An agent timeout blocks tests; a test timeout blocks push and PR creation.
 
 ## PR and release gate
 
@@ -71,3 +76,6 @@ Terminal failure states are `claim_failed`, `agent_failed`, `tests_failed`, and
 6. Passing tests produce a linked PR request with evidence.
 7. Existing state/PR prevents duplicate work.
 8. Dry-run against live Gitea returns a plan and performs no mutation.
+9. A timed-out command terminates its descendants and returns within its deadline plus grace period.
+10. Agent and test timeouts persist distinct terminal states and block every later delivery stage.
+11. Non-positive deadline configuration aborts before issue claim.