Delegated child tasks get no rootTask and taskNumber 1 #2031

Problem

After delegation, the child task has no root-task pointer. Parent and child both have task number 1.

createTask reads the task registry for both values (src/core/webview/ClineProvider.ts, around lines 3426-3428):

rootTask: this.taskRegistry.getAll()[0],
taskNumber: this.taskRegistry.length + 1,

delegateParentAndOpenChildUnlocked removes the parent from the registry during disposal (around line 3907). It calls createTask for the child afterward (around line 3927). The registry is empty at that point. So rootTask is undefined and taskNumber is 1.

Evidence

A server-state audit of a delegation run showed parent links agree and transcripts parse. Both defects appeared as metadata only. The code path was read but not reproduced at runtime. Confirm with a test before fixing.

Effects

1. Any consumer of rootTask cannot find the root for a child. Deeper hierarchies (child of child) are the risk.
2. taskNumber is not unique across a hierarchy.

Proposed fix

Derive both values from the parent when parentTask is set. For example:

1. rootTask: parentTask?.rootTask ?? parentTask ?? this.taskRegistry.getAll()[0]
2. A taskNumber rule that does not depend on the emptied registry.

Decide the intended taskNumber meaning first. Check whether the ...options spread after these fields can override them.

Tests

1. Delegate parent to child. Assert child.rootTask is the parent task.
2. Delegate to a grandchild. Assert rootTask is the original parent and the task numbers are unique.

Related

This may fit the parallelizable tasks work (#355). It is not related to PR #1906.