Workflow "Plan" no longer duplicates the planner (phase1/3 already build a
structured plan and auto-populate todo); adds an observe/act carve-out so
observe requests don't get pushed to create a todo. New "System signals
you'll see" subsection names the runtime-injected messages ([Goal anchor],
[Scope boundary], [Anti-stall warning], [Iteration N/M]) so the model
recognises them as machinery and responds correctly — and corrects the
factual error that the goal anchor reads scratchpad `goal` (it reads the
original request + live todo). Closing paragraph warns that thinking isn't
re-injected and the plan's per-step executor assignments are lost to
compression, so conclusions/assignments should go in scratchpad.

Co-Authored-By: Claude <noreply@anthropic.com>