04 — QT Path Preservation Check (Supertrack D)

Goal: confirm Stage 0 does not damage live valid birth paths. Views: v_birth_qt_path_preservation_status, v_birth_qt_stage0_block_reason. No QT worsened (regression RGT8 = PASS).

QT	Before Stage 0	After Stage 0	Worsened?	Why
QT-001	BROKEN/RISKY (backfill incompat 22/36)	EXPLICITLY_BLOCKED (backfill frozen)	No	Already broken; freeze makes the block explicit + safe
QT-002	LIVE (fn_birth_registry_auto guarded + fn_birth_gate)	LIVE_UNCHANGED	No	Gateway fn + 166 triggers untouched; no_old_function_guard PASS
QT-003	SOFT; calls trigger-setup	SOFT; trigger-setup step skipped	No	dot-collection-create -x +
QT-003R	SOFT	SOFT_UNCHANGED	No	Register step has no dependency on frozen DOTs
QT-005	detect-only	UNCHANGED	No	No dependency on frozen DOTs
QT-006	ABSENT (no death trigger)	ABSENT_UNCHANGED	No	Out of Stage 0 scope (Stage 5)

Live confirmations

• BIRTH_REQUIRED still births: gateway intact (guard PASS), 166 triggers present.
• BIRTH_EXEMPT still skips: gateway retains coverage_status / BIRTH_EXEMPT logic.
• No source row mutation: birth_registry count linear (1,210,834→1,210,839), no spike.

Completion: Stage 0 prevents dangerous tooling without damaging the live valid birth path.