experiments: freeze feedback-first C2 screen

1 files changed, 9 insertions, 0 deletions

diff --git a/ROADMAP.md b/ROADMAP.md
index 60591c9..677243e 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -185,6 +185,15 @@ context-gated simultaneous K1/e4 joint phase. The prefix uses layerwise K4 targe
 `eta_A=0.01`; its length grid and selection rule must be committed before any run. This tests the
 specific coupled-basin diagnosis without increasing vectorizer capacity or changing the task.
 
+The frozen prefix-length grid is `{0, 100, 400}` A-only minibatches, crossed with d1/d4 and model
+seeds 0--2. Warmup consumes an isolated RNG stream and restores the loader generator, so every
+candidate's subsequent joint phase receives the same minibatch order and perturbation randomness.
+A prefix is development-eligible only if all six final losses are finite, mean d4 validation is at
+least 90%, at least 2/3 paired depth gains are positive, and the d4 lesion loses at least 2 points
+on average with at least 2/3 positive lesions. Among eligible prefixes, select the highest mean d4
+endpoint, choosing the shortest prefix within one point. If none is eligible, the feedback-first
+branch closes without using task seeds 6--8.
+
 ### C3. Causal calibration is genuinely amortized
 
 **Status: passed on 2026-07-22.** The frozen five-seed confirmation retained 112.9% of the K16/e4