research: Dütsch error budget — settling at one fifth of comparison bands, conservative drift

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/validation/duetsch_re100_kc5_protocol.md

@@ -134,12 +134,19 @@ ledger; verdict PASS or FAIL-CLOSED.
 Scales: `F_ref = 0.5 rho U_max² D`, `U_ref = U_max`; never a near-zero mean
 force as denominator.
 
-- Settling metrics, cycle k−1 → k, phase-aligned by step within the cycle:
-  - waveform `RMS(dFx) / F_ref ≤ .02`;
-  - `|d mean|`, `|d RMS|`, `|d peak|` of Fx, each `/ F_ref ≤ .01`;
-  - scored profiles (fluid-only) `|du| / U_max`, `|dv| / U_max ≤ .03` at the
+- Settling metrics, cycle k−1 → k, phase-aligned by step within the cycle
+  (error budget: one fifth of the tightest comparison band of the same
+  observable, so residual drift cannot obscure a domain or resolution pass):
+  - waveform `RMS(dFx) / F_ref ≤ .002`;
+  - `|d mean|`, `|d RMS|`, `|d peak|` of Fx, each `/ F_ref ≤ .002`;
+  - scored profiles (fluid-only) `|du| / U_max`, `|dv| / U_max ≤ .004` at the
     three phases × four stations;
-  - Morison `|dc_d| ≤ .02`, `|dc_i| ≤ .02`.
+  - Morison `|dc_d| ≤ .004`, `|dc_i| ≤ .004`.
+- Conservative comparison: every domain and cross-resolution criterion is
+  applied to `|difference| + drift_a + drift_b`, where drift is the largest
+  pair metric of that case inside the scored window.
+- These constants (protocol.py SETTLE, DOMAIN, CROSS) are frozen before any
+  physical result; no post-result loosening.
 - Rule: all metrics for N = 3 consecutive whole paper cycles → settled.
 
 Cycle indexing (worked example, binding). Paper cycle k spans