docs: rebalance prose cleanup and add trimming skill

packages/workflow/workflow-workerthread/src/session.ts

@@ -1,7 +1,13 @@
 /**
  * The worker-side half of the engine: {@link runWorkerSession} wires one MessagePort to one
  * {@link WorkflowExecution} — hook progress and child starts go out as messages, run control
- * and child lifecycle come back in — and posts the run's terminal result exactly once.
+ * and child lifecycle come back in — and posts the run's terminal result exactly once. Keeping it
+ * separate from `worker.ts` lets unit tests drive the session over a MessageChannel, because main
+ * process coverage cannot observe code inside a real Worker.
+ *
+ * The session announces ready and waits for `go`, so cancellation racing startup can prevent even
+ * the script's synchronous prefix. A cancel in place of `go` releases the gate into a cancelled
+ * drive without executing the body.
  * @module @deepseek-ai/dsh-workflow-workerthread/session
  */
 
@@ -127,8 +133,9 @@ export function requireParentPort(port: MessagePort | null): MessagePort {
 /**
  * Run one workflow script to settlement against `port`, posting the terminal result message
  * exactly once; resolves after that post (stray children may still be winding down through the
- * port — the host owns their teardown and ultimately terminates the thread).
- *
+ * port — the host owns their teardown and ultimately terminates the thread). It never rejects:
+ * constructor failure becomes an error result. Host pre-parse makes syntax failure here a likely
+ * Node-version skew, but the session still reports it instead of dying silently.
  * @param port - the channel to the host (the real `parentPort`, or one side
  *   of an in-process `MessageChannel` in tests).
  * @param init - the run payload the host provided as `workerData`.