[Pause] Reject queries when workflow is paused

[gow]

What changed?

• Querying a paused workflow returns a "rejected" response.
• Added functional test.

Why?

Executing queries on a paused workflow may not provide the updated results since the server withholds events from the worker when a workflow is paused. This breaks the current expectation of read-after-write semantics of Query API. Ex: When a client sends a signal to the workflow and follows up with a query, the expectation is that the query result includes the effect of the signal. But for a paused workflow that guarantee cannot be provided. So we are failing the queries in a paused workflow for now.

How did you test it?

• built
• run locally and tested manually
• covered by existing tests
• added new unit test(s)
• added new functional test(s)

---

Note

Queries against paused workflows now return QueryRejected with PAUSED status; adds a functional test to validate behavior.

• History API:
  • service/history/api/queryworkflow/api.go: When mutableStateStatus is WORKFLOW_EXECUTION_STATUS_PAUSED, return QueryRejected with status PAUSED.
• Tests:
  • tests/pause_workflow_execution_test.go: Add TestQueryWorkflowWhenPaused to verify querying a paused workflow returns QueryRejected with PAUSED status.

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