Pure-logic smoke (no LLM, no DB) that builds a synthetic ledger by hand and asserts
the Phase-A substrate stays coherent: full F1->F8 walk reaches terminal phase
(max+1); rollback truncates the effective view (stale phase-7 decision excluded
after reopen to F4) and resets current_phase; teardown deletes artifacts beyond the
target while preserving the target phase's; re-approve after rollback advances
correctly; taskdoc stays under byte budget across all phases; decision_retraction
excludes the retracted seq + the marker itself from effective_decisions.
This is the CI-runnable coherence net for the L2 session test (which exercises the
LLM->gate loop that L1 cannot).
marcopan