fix: bound worker hello and cancel reconnect backoff

[wangbill (YunchuWang)]

Summary

• apply a 30-second grpc-js deadline to every worker sidecar Hello attempt
• log and retry initial and reconnect Hello failures using the existing event-driven retry path
• cancel pending Hello calls and reconnect backoff when stop() is called

Review guide

1. backoff.util.ts: add optional AbortSignal support to the existing delay.
2. task-hub-grpc-worker.ts: create one signal per start, apply the Hello deadline, pass the signal through existing retries, and abort/cancel it from stop.
3. Startup/backoff tests: prove deadline, retry, and cancellation behavior.

The final worker diff is 101 additions / 24 deletions. It preserves the existing event-driven worker; there is no WorkerLifecycle, connection-loop rewrite, or drained-stop contract.

Scope

This intentionally preserves the existing non-blocking start() contract and event-driven worker structure. It does not add startup readiness semantics or a drained connection-loop lifecycle, so it is related to but does not close #69.

Validation

• focused startup/backoff/stream-recovery tests
• full durabletask-js test suite
• core build, ESLint, Prettier, and diff checks

[Copilot]

Pull request overview

This PR changes TaskHubGrpcWorker.start() semantics so that awaiting startup only resolves after the sidecar “hello” handshake succeeds and the initial work-item stream is confirmed ready, with a configurable startup timeout budget (default 30s). It also wires the new timeout knob through the Azure-managed worker builder and updates docs/changelogs accordingly.

Changes:

• Make await worker.start() wait for hello + initial work-item stream readiness, with a bounded startupTimeoutMs covering metadata generation, hello, and stream readiness.
• Add comprehensive unit tests for startup timing, cancellation, late callbacks, and stream recovery behavior.
• Expose .startupTimeout(milliseconds) on DurableTaskAzureManagedWorkerBuilder and document the new startup semantics.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
README.md	Documents new start() readiness semantics and builder timeout configuration.
CHANGELOG.md	Notes the core worker startup behavior change.
packages/durabletask-js/src/worker/task-hub-grpc-worker.ts	Implements startup readiness gating, startup timeout budget, and generation-based cancellation/cleanup.
packages/durabletask-js/test/worker-startup.spec.ts	Adds focused tests covering startup readiness, timeouts, stop-during-start, and late callbacks.
packages/durabletask-js/test/worker-stream-recovery.spec.ts	Adjusts mocks to account for metadata-based “stream ready” detection.
packages/durabletask-js-azuremanaged/src/worker-builder.ts	Adds .startupTimeout() builder method and passes it into core worker options.
packages/durabletask-js-azuremanaged/test/unit/worker-builder.spec.ts	Verifies builder propagates startup timeout to the core worker instance.
packages/durabletask-js-azuremanaged/README.md	Documents startup readiness and builder timeout configuration.
packages/durabletask-js-azuremanaged/CHANGELOG.md	Notes the new builder API for startup timeout configuration.

[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated no new comments.

Suppressed comments (2)

packages/durabletask-js/src/worker/task-hub-grpc-worker.ts:425

• The start() @throws doc is too narrow: start() can now throw TimeoutError for metadata generation and work-item stream establishment timeouts as well, not only the hello handshake.

   * @throws {@link TimeoutError} if the hello handshake exceeds `startupTimeoutMs`.

packages/durabletask-js/src/worker/task-hub-grpc-worker.ts:71

• The TaskHubGrpcWorkerOptions.startupTimeoutMs doc comment no longer matches behavior: the timeout budget is also applied to work-item stream metadata generation and establishing the initial stream, not just hello/metadata. Updating the comment helps avoid confusing API consumers.

  /**
   * Optional timeout in milliseconds for initial metadata generation and the sidecar hello handshake.
   * Defaults to 30000.
   */
  startupTimeoutMs?: number;

[Copilot]

Pull request overview

Copilot reviewed 11 out of 11 changed files in this pull request and generated no new comments.

[wangbill (YunchuWang)]

why this tests is separate