## Summary
Ordered task steps can no longer appear active ahead of unfinished
predecessors. Step starts now use the same dependency-aware ordering
guard as completions, while steps explicitly declared independent remain
parallelizable. Rejected executor updates explain that the lifecycle
transition was suppressed instead of implying completed work was
overwritten.
## Validation
- Reproduced the FN-8490 concurrent update sequence and verified later
steps remain pending.
- Passed 15 PostgreSQL step-order tests, the focused executor response
test, core and engine typechecks, changeset validation, and `pnpm
verify:fast` including boot smoke.
- The full `executor-prompt.test.ts` run retains five pause-behavior
expectation failures that reproduce unchanged on `origin/main`.
<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit
* **New Features**
* Enhanced the step start hook to support an awaited “pre-start
projection” that can reject startup via `false` (sync or async),
preventing step-session creation/completion.
* Added a step-start “verdict” so steps can be started or blocked
deterministically (including “resumed” behavior).
* **Bug Fixes**
* Prevented ordered/dependency steps from transitioning out-of-order by
enforcing guards for both in-progress and done transitions, including
concurrent update attempts.
* Improved integrity/out-of-order warning behavior and suppression
details when persisted status doesn’t match expectations.
* **Tests**
* Added/updated PostgreSQL and engine regression coverage for
blocked/resumed start and start-rejection control flow.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
d194290a75