[plan] Project memory: open the pipe, honest trust

_Automatically composed from the parent epic at dispatch time._

6 coder children, one per subtask, split by the Architect's boundaries: C0 plan switch (phase 1); C1/C2/C3/C5 (phase 2); C4 after C2 (phase 3, restore dep). S4-2: followed PRD over Arch §2.2 Repro precondition. No Required checks line (mem-11178). Traps tightened into Done means. Used mem-14220, mem-17928.