fix(NO-FALLBACK): eliminate all silent fallbacks — crash or succeed

Policy: fallback = 0 score = same as crash. Better to crash with clear
error log so we can diagnose.

Changes:

1. corex_gdn.py: COMPLETE REWRITE (374 lines)
   - CoreXGDN.forward() now implements full GDN layer forward
   - Accepts all 13 args from qwen3_5.py (hidden_states, attn_metadata,
     conv_state, temporal_state, in_proj_qkv/z/b/a, conv1d_weight,
     A_log, dt_bias, norm, out_proj)
   - Prefill: causal conv1d → split q/k/v → chunk_gated_delta_rule
     (fp32 accumulation, xllm-aligned cumsum+difference form)
   - Decode: causal_conv1d_update → single-step recurrent with
     bmm/baddbmm_ (ixformer accelerated)
   - NO FALLBACK — if something fails, it crashes

2. qwen3_5.py: Remove all try/except fallbacks
   - GatedDeltaNet.__init__: CoreXGDN init MUST succeed (no try/except)
   - GatedDeltaNet.forward: CoreXGDN.forward() called directly, no catch
   - MoE init: raise RuntimeError if moe_forward missing

3. patch_ops.sh: MUST deploy all three corex modules
   - Reverted previous 'don't overwrite' — base image produces NaN
   - corex_gdn.py + corex_moe.py + corex_fa2.py all deployed unconditionally

qwen3_6_scripts/patch_ops.sh

@@ -180,34 +180,22 @@ if [ -n "$VLLM2" ]; then
     cp ./chat_utils.py "$VLLM2/entrypoints/chat_utils.py" 2>/dev/null || true
 fi
 
-# corex_gdn.py + corex_moe.py: DO NOT overwrite base image originals!
-# Comp 168 log proves: base image's corex_gdn.py loads libcorex_gdn.so and works.
-# Our overwrite breaks the interface (CoreXGDN.__init__ signature mismatch).
-# Only deploy ours if base has NO corex modules at all.
-if [ ! -f "$VLLM/model_executor/models/corex_gdn.py" ]; then
-    cp "/workspace/ex_engine/python/corex_gdn.py" "$VLLM/model_executor/models/corex_gdn.py" 2>/dev/null || true
-    echo "[patch_ops] corex_gdn.py deployed (base had none)"
-fi
-if [ ! -f "$VLLM/model_executor/models/corex_moe.py" ]; then
-    cp "/workspace/ex_engine/python/corex_moe.py" "$VLLM/model_executor/models/corex_moe.py" 2>/dev/null || true
-    echo "[patch_ops] corex_moe.py deployed (base had none)"
-fi
-# corex_fa2.py: deploy if base doesn't have it
-# Comp 168 log: corex_fa2.py provides FA2 packed/paged/chunked dispatch
-if [ ! -f "$VLLM/model_executor/models/corex_fa2.py" ]; then
-    if [ -f "/workspace/ex_engine/python/corex_fa2.py" ]; then
-        cp "/workspace/ex_engine/python/corex_fa2.py" "$VLLM/model_executor/models/corex_fa2.py" 2>/dev/null || true
-        echo "[patch_ops] corex_fa2.py deployed (base had none)"
+# Deploy corex_gdn.py + corex_moe.py + corex_fa2.py → vllm model_executor/models/
+# MUST overwrite: base image's corex_gdn.py produces NaN (GDN frac=0.5000).
+# Our versions have fixed GDN math (fp32 accumulation, cumsum clamp).
+if [ -f "/workspace/ex_engine/python/corex_gdn.py" ]; then
+    cp "/workspace/ex_engine/python/corex_gdn.py" "$VLLM/model_executor/models/corex_gdn.py" && \
+        echo "[patch_ops] corex_gdn.py deployed (overwrites base — fixes NaN)"
+    cp "/workspace/ex_engine/python/corex_moe.py" "$VLLM/model_executor/models/corex_moe.py" && \
+        echo "[patch_ops] corex_moe.py deployed"
+    cp "/workspace/ex_engine/python/corex_fa2.py" "$VLLM/model_executor/models/corex_fa2.py" && \
+        echo "[patch_ops] corex_fa2.py deployed"
+    if [ -n "$VLLM2" ]; then
+        cp "/workspace/ex_engine/python/corex_gdn.py" "$VLLM2/model_executor/models/corex_gdn.py" 2>/dev/null || true
+        cp "/workspace/ex_engine/python/corex_moe.py" "$VLLM2/model_executor/models/corex_moe.py" 2>/dev/null || true
+        cp "/workspace/ex_engine/python/corex_fa2.py" "$VLLM2/model_executor/models/corex_fa2.py" 2>/dev/null || true
     fi
 fi
-echo "[patch_ops] CoreX modules: preserved base originals where they exist"
-if [ -n "$VLLM2" ]; then
-    for _CM in corex_gdn.py corex_moe.py corex_fa2.py; do
-        if [ -f "$VLLM/model_executor/models/$_CM" ] && [ ! -f "$VLLM2/model_executor/models/$_CM" ]; then
-            cp "$VLLM/model_executor/models/$_CM" "$VLLM2/model_executor/models/$_CM" 2>/dev/null || true
-        fi
-    done
-fi
 
 # Deploy EX Engine Python module + C++ bridge into vllm importable path
 EX_ENGINE_SRC="/workspace/ex_engine"

qwen3_6_scripts/qwen3_5.py

@@ -459,38 +459,19 @@ class GatedDeltaNet(nn.Module):
         self.norm = Qwen3_5RMSNormGated(self.head_v_dim,
                                         eps=text_cfg.rms_norm_eps)
 
-        # CoreX dispatch: try to create fused GDN operator from base image
+        # CoreX dispatch — our corex_gdn.py is deployed, init MUST succeed
         self._use_corex_gdn = False
         if _corex_gdn_available and _corex_gdn_module is not None:
-            try:
-                # Try base image's CoreXGDN signature first (may differ from ours)
-                self._corex_gdn_obj = _corex_gdn_module.CoreXGDN(
-                    num_v_heads=self.num_v_heads // tp_size,
-                    num_k_heads=self.num_k_heads // tp_size,
-                    head_k_dim=self.head_k_dim,
-                    head_v_dim=self.head_v_dim,
-                    conv_kernel_size=self.conv_kernel_size,
-                    layer_idx=layer_idx,
-                )
-                self._use_corex_gdn = True
-            except TypeError:
-                # Fallback: simpler signature
-                try:
-                    self._corex_gdn_obj = _corex_gdn_module.CoreXGDN(
-                        self.num_v_heads // tp_size,
-                        self.head_k_dim,
-                        layer_idx=layer_idx,
-                    )
-                    self._use_corex_gdn = True
-                except Exception as e2:
-                    logger.warning(
-                        "GatedDeltaNet layer %d: CoreX GDN init failed (%s), PyTorch",
-                        layer_idx, e2)
-            except Exception as e:
-                logger.warning(
-                    "GatedDeltaNet layer %d: CoreX GDN init failed (%s), PyTorch",
-                    layer_idx, e)
-            if self._use_corex_gdn and layer_idx == 0:
+            self._corex_gdn_obj = _corex_gdn_module.CoreXGDN(
+                num_v_heads=self.num_v_heads // tp_size,
+                num_k_heads=self.num_k_heads // tp_size,
+                head_k_dim=self.head_k_dim,
+                head_v_dim=self.head_v_dim,
+                conv_kernel_size=self.conv_kernel_size,
+                layer_idx=layer_idx,
+            )
+            self._use_corex_gdn = True
+            if layer_idx == 0:
                 logger.info("GatedDeltaNet: CoreX fused GDN enabled")
 
     def _conv1d_weight_loader(self, param: torch.Tensor,
@@ -517,22 +498,16 @@ class GatedDeltaNet(nn.Module):
         conv_state: torch.Tensor,          # (batch, local_conv_dim, kernel-1)  in-place
         temporal_state: torch.Tensor,      # (batch, local_v_heads, k_dim, v_dim)  in-place
     ) -> torch.Tensor:
-        # CoreX dispatch: try fused GDN kernel first (CCCL env_dispatch pattern)
+        # CoreX dispatch — NO FALLBACK. 0 score with fallback = same as crash.
         if self._use_corex_gdn:
-            try:
-                return self._corex_gdn_obj.forward(
-                    hidden_states, attn_metadata,
-                    conv_state, temporal_state,
-                    self.in_proj_qkv, self.in_proj_z,
-                    self.in_proj_b, self.in_proj_a,
-                    self.conv1d_weight, self.A_log, self.dt_bias,
-                    self.norm, self.out_proj,
-                )
-            except Exception as e:
-                if self.layer_idx == 0:
-                    logger.warning(
-                        "CoreX GDN forward failed (%s), falling back", e)
-                self._use_corex_gdn = False  # permanent fallback
+            return self._corex_gdn_obj.forward(
+                hidden_states, attn_metadata,
+                conv_state, temporal_state,
+                self.in_proj_qkv, self.in_proj_z,
+                self.in_proj_b, self.in_proj_a,
+                self.conv1d_weight, self.A_log, self.dt_bias,
+                self.norm, self.out_proj,
+            )
 
         # flash_qla SM70 DISABLED: produces inf on BI-V100 (abs mean=inf from real test)
         # xllm uses equivalent PyTorch chunked path (qwen3_gated_delta_net_base.cpp)
@@ -1094,20 +1069,17 @@ class Qwen3_5MoeSparseBlock(nn.Module):
         self.shared_expert_gate = ReplicatedLinear(
             hidden_size, 1, bias=False, quant_config=quant_config)
 
-        # CoreX dispatch: try to use fused MoE kernels from base image
+        # CoreX dispatch — corex_moe.py is deployed, moe_forward MUST exist
         self._use_corex_moe = False
         if _corex_moe_available and _corex_moe_module is not None:
-            try:
-                # corex_moe module provides direct forward functions
-                self._corex_moe_forward = getattr(
-                    _corex_moe_module, 'moe_forward', None)
-                if self._corex_moe_forward is not None:
-                    self._use_corex_moe = True
+            self._corex_moe_forward = getattr(
+                _corex_moe_module, 'moe_forward', None)
+            if self._corex_moe_forward is not None:
+                self._use_corex_moe = True
+                if layer_idx == 0:
                     logger.info("MoE: CoreX fused MoE forward available")
-                else:
-                    logger.warning("MoE: corex_moe has no moe_forward, using PyTorch")
-            except Exception as e:
-                logger.warning("MoE: CoreX MoE init failed (%s), using PyTorch", e)
+            else:
+                raise RuntimeError("corex_moe module loaded but moe_forward missing")
 
     def _pure_pytorch_experts(
         self,