fix(rivetkit-core): defer teardown_started until drain settles

[NathanFlurry]

Stack Context

This stack fixes actor sleep driver-test failures around work registered during shutdown grace and a deprecated fixture sleep hold.

Why?

teardown_sleep_state() set teardown_started before draining accepted shutdown tasks, so nested waitUntil work registered while the drain was active could be refused. It also relied on task-count changes without waking the actor grace loop, which could leave shutdown waiting until the grace deadline.

What?

This PR wakes the grace loop when shutdown tasks are registered or finish, drains accepted tasks until the join set settles before setting teardown_started, and keeps the deadline path as aborting cleanup by marking when the grace deadline was reached.

Validation

• cargo test -p rivetkit-core sleep_shutdown_waits_for_keep_awake_work_then_finishes_next_tick
• cargo test -p rivetkit-core ctx_wait_until_during_finish_shutdown_cleanup_refused_without_leak
• cargo test -p rivetkit-core destroy_shutdown_concurrent_wait_until_refused
• cargo test -p rivetkit-core destroy_shutdown_times_out_at_deadline_and_aborts_stuck_shutdown_task
• cargo test -p rivetkit-core keep_awake_region_blocks_sleep_idle_until_guard_drops
• cargo test -p rivetkit-core nested_wait_until_during_grace_is_drained
• cargo test -p rivetkit-core keep_awake_in_on_sleep_blocks_finalize_until_released
• pnpm build:force
• pnpm test tests/driver/actor-sleep-db.test.ts -t "static registry.*encoding \\(bare\\).*nested waitUntil inside waitUntil"

[railway-app]

🚅 Deployed to the rivet-pr-4836 environment in rivet-frontend

Service	Status	Web	Updated (UTC)
website	✅ Success (View Logs)	Web	Apr 28, 2026 at 12:43 pm
frontend-cloud	😴 Sleeping (View Logs)	Web	Apr 28, 2026 at 12:14 pm
ladle	✅ Success (View Logs)	Web	Apr 28, 2026 at 6:10 am
mcp-hub	✅ Success (View Logs)	Web	Apr 28, 2026 at 6:10 am
frontend-inspector	❌ Build Failed (View Logs)	Web	Apr 28, 2026 at 6:09 am
kitchen-sink	❌ Build Failed (View Logs)	Web	Apr 28, 2026 at 6:09 am

[NathanFlurry]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• fix(rivetkit-core): defer teardown_started until drain settles #4836 👈 (View in Graphite)
• test(rivetkit-core): cover nested wait_until and keep_awake-during-grace #4835
• fix(rivetkit-core): reject non-/request actor http paths #4826
• test(rivetkit): import vi for actor-queue waitFor #4825
• test(rivetkit): restore sleep wait before post-sleep integrity check #4824
• fix(rivetkit): retry connection when getParams throws #4823
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[github-actions]

Preview packages published to npm

Install with:

npm install rivetkit@pr-4836

All packages published as 0.0.0-pr.4836.ca70b4c with tag pr-4836.

Engine binary is shipped via @rivetkit/engine-cli on linux-x64-musl, linux-arm64-musl, darwin-x64, and darwin-arm64. Windows users should use the release installer or set RIVET_ENGINE_BINARY.

Docker images:

docker pull rivetdev/engine:slim-ca70b4c
docker pull rivetdev/engine:full-ca70b4c

Individual packages

npm install rivetkit@pr-4836
npm install @rivetkit/react@pr-4836
npm install @rivetkit/rivetkit-napi@pr-4836
npm install @rivetkit/workflow-engine@pr-4836