diff --git a/conf/gtauav_baseline.gin b/conf/gtauav_baseline.gin
index 3bcadde..26ae7e3 100644
--- a/conf/gtauav_baseline.gin
+++ b/conf/gtauav_baseline.gin
@@ -1,9 +1,21 @@
 # GTA-UAV Baseline: no text fusion (gate forced to 1.0).
 # query = drone_only -> InfoNCE vs satellite
 # Reference R@1 for delta computation.
+#
+# Diagnostic mode (2026-04-24): DSS and hard-negative mining disabled after
+# the previous run collapsed (R@1 = 0.6% at epoch 8, train loss growing).
+# Hypothesis: DSS packs visually-identical drones at bs=8 and the hard-mining
+# queue amplifies that hardness — together they prevent convergence from a
+# nearly-random start. Run with mutex-only sampling and the full queue as
+# uniform negatives first, restore the extras incrementally once baseline
+# converges.
 
 include 'conf/gtauav_balanced.gin'
 
 TrainConfigGTAUAV.baseline_mode = True
-TrainConfigGTAUAV.output_dir = "out/gtauav/baseline"
+TrainConfigGTAUAV.output_dir = "out/gtauav/baseline_mutex"
 TrainConfigGTAUAV.use_gradcam = False
+
+# ---- Diagnostic overrides ----
+TrainConfigGTAUAV.sampler_type = "mutex"  # was "dss" — disable hard-batch construction
+InfoNCELoss.hard_mining_k = 0  # was 512 — use full queue without per-query top-K