add open-task diagnostics to orchestration execution logging

[solankisamir]

Summary

This change improves diagnostics for orchestrations that appear stuck (for example, when no new durable actions are scheduled but the orchestration is still waiting on pending work). We had this problem in our Test environment, where an orchestration reached a point and then there were no logs from the application. It looks like the orchestration was hung.

What changed

1. Added open-task diagnostics to orchestration execution flow:

   • OpenTaskCount
   • OpenTaskNames (e.g., ActivityName#12, Timer#8)

2. Captured and propagated this data through execution objects:

   • TaskOrchestrationContext
   • OrchestratorExecutionResult (internal + [JsonIgnore])
   • OrchestrationExecutionCursor
   • TaskOrchestrationExecutor
   • TaskOrchestrationDispatcher

3. Extended structured logging for OrchestrationExecuted:

   • LogEvents.OrchestrationExecuted now includes open-task fields
   • LogHelper.OrchestrationExecuted now passes open-task fields
   • StructuredEventSource.OrchestrationExecuted signature updated accordingly

Why

When an orchestration has 0 new decisions but still has open tasks, troubleshooting is difficult because logs only show action count. Including open-task count and names provides immediate visibility into what the orchestration is currently waiting on.

Scope

Diagnostics/logging only. No orchestration behavior changes.

[Copilot]

Pull request overview

Note

Copilot was unable to run its full agentic suite in this review.

Adds richer diagnostics to orchestration execution logging by capturing how many tasks an orchestration is currently waiting on and a short summary of those tasks.

Changes:

• Populate OrchestratorExecutionResult and OrchestrationExecutionCursor with open-task count and a task summary.
• Extend structured logging (OrchestrationExecuted) to include open-task diagnostics in both event source and log message.
• Update dispatcher flow to pass these diagnostics through to logging.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/DurableTask.Core/TaskOrchestrationExecutor.cs	Captures open-task diagnostics into the execution result.
src/DurableTask.Core/TaskOrchestrationDispatcher.cs	Threads open-task diagnostics from execution result/cursor into logging calls.
src/DurableTask.Core/TaskOrchestrationContext.cs	Adds APIs to compute open-task count and a summary string.
src/DurableTask.Core/OrchestratorExecutionResult.cs	Adds non-serialized diagnostic fields for open tasks.
src/DurableTask.Core/OrchestrationExecutionCursor.cs	Stores open-task diagnostics on the cursor.
src/DurableTask.Core/Logging/StructuredEventSource.cs	Extends event signature/payload to include open-task diagnostics.
src/DurableTask.Core/Logging/LogHelper.cs	Extends helper API to pass open-task diagnostics into structured log event.
src/DurableTask.Core/Logging/LogEvents.cs	Persists new structured fields and includes them in the human-readable message.

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