Document ContinueAsNew trace behavior

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: chandramouleswaran

docs/telemetry/distributed-tracing.md

@@ -209,6 +209,24 @@ Traces are automatically correlated across:
 - Orchestration → Activity
 - Client → Orchestration
 
+### Continue-as-new trace behavior
+
+By default, `ContinueAsNew` preserves the current distributed trace context. This keeps generations of the same orchestration instance connected in one trace.
+
+For long-running or periodic orchestrations, use `ContinueAsNewOptions` with `ContinueAsNewTraceBehavior.StartNewTrace` to start the next generation in a fresh trace:
+
+```csharp
+context.ContinueAsNew(
+    newVersion: null,
+    input: nextInput,
+    options: new ContinueAsNewOptions
+    {
+        TraceBehavior = ContinueAsNewTraceBehavior.StartNewTrace,
+    });
+```
+
+The orchestration instance ID is preserved, but the next generation gets a new trace ID. Use this when each loop or cycle should be independently visible in your telemetry backend.
+
 ### Example Trace Hierarchy
 
 ```text

docs/telemetry/traces/semantic-conventions.md

@@ -69,6 +69,12 @@ Attributes:
 | durabletask.task.execution_id  | Execution ID of the enqueued orchestration  |
 | exception.*  | Exception details on failure. |
 
+##### Continue-as-new fresh traces
+
+When `ContinueAsNew` is used with `ContinueAsNewTraceBehavior.StartNewTrace`, DurableTask emits this producer span shape for the next generation even though no external client call occurred. The producer span is the root of a new trace, starts at the next generation's orchestration-created timestamp, and ends when the worker establishes the trace before running the generation.
+
+The following `orchestration:{orchestrationName}(@{orchestrationVersion})?` server span is a child of this producer span. The orchestration instance ID is preserved, but the new generation is not parented to the previous generation's trace.
+
 #### Client: Starting a sub-orchestration
 
 Represents enqueueing and waiting for a sub-orchestration to complete