diff --git a/crates/ml-alpha/src/cfc/trunk.rs b/crates/ml-alpha/src/cfc/trunk.rs
index c8bf4f10d..4423a14bb 100644
--- a/crates/ml-alpha/src/cfc/trunk.rs
+++ b/crates/ml-alpha/src/cfc/trunk.rs
@@ -19,7 +19,7 @@ use rand::{Rng, SeedableRng};
 use rand_chacha::ChaCha8Rng;
 
 use crate::cfc::snap_features::{Mbp10RawInput, ES_TICK_SIZE, FEATURE_DIM, REGIME_DIM};
-use crate::heads::{HIDDEN_DIM, N_HORIZONS, PROJ_DIM};
+use crate::heads::{HEAD_MID_DIM, HIDDEN_DIM, N_HORIZONS, PROJ_DIM};
 use serde::{Deserialize, Serialize};
 
 /// On-disk checkpoint envelope for CfcTrunk weights. Bumped version on
@@ -51,11 +51,15 @@ const PROJ_CUBIN: &[u8] = include_bytes!(concat!(env!("OUT_DIR"), "/projection.c
 pub struct CfcConfig {
     pub n_in: usize,
     pub n_hid: usize,
+    /// Mamba2 state dimension — used by the v2 trunk weight skeleton
+    /// (X1) and the per-stack Mamba2Block constructions added in X3/X5.
+    /// Default matches `PerceptionTrainerConfig::default().mamba2_state_dim`.
+    pub mamba2_state_dim: usize,
 }
 
 impl Default for CfcConfig {
     fn default() -> Self {
-        Self { n_in: FEATURE_DIM, n_hid: HIDDEN_DIM }
+        Self { n_in: FEATURE_DIM, n_hid: HIDDEN_DIM, mamba2_state_dim: 16 }
     }
 }
 
@@ -73,7 +77,9 @@ pub struct CfcTrunk {
     heads_fn: CudaFunction,
     proj_fn: CudaFunction,
 
-    // Device-resident weights
+    // Device-resident weights — V1 (CfC + simple heads + projection).
+    // Preserved unchanged until X8/X9 consolidate against the v2 fields
+    // added below.
     w_in_d: CudaSlice<f32>,
     w_rec_d: CudaSlice<f32>,
     b_d: CudaSlice<f32>,
@@ -85,6 +91,29 @@ pub struct CfcTrunk {
     proj_g_d: CudaSlice<f32>,
     proj_n_d: CudaSlice<f32>,
 
+    // === V2 weight skeleton (X1) — zero-initialised slabs + None for
+    // Mamba2 stacks. Each is wired in a subsequent commit (X2..X9):
+    //   X2 VSN, X3 Mamba2_l1, X4 LN_a, X5 Mamba2_l2, X6 LN_b,
+    //   X7 attn_pool, X8 CfC consolidation, X9 GRN heads.
+    // Public so PerceptionTrainer can read them during migration —
+    // visibility tightens to crate-private after X10 hoists the
+    // forward kernels into CfcTrunk methods. ===
+    pub vsn_w_d: CudaSlice<f32>,
+    pub vsn_b_d: CudaSlice<f32>,
+    pub mamba2_stack_1: Option<crate::mamba2_block::Mamba2Block>,
+    pub mamba2_stack_2: Option<crate::mamba2_block::Mamba2Block>,
+    pub ln_a_gain_d: CudaSlice<f32>,
+    pub ln_a_bias_d: CudaSlice<f32>,
+    pub ln_b_gain_d: CudaSlice<f32>,
+    pub ln_b_bias_d: CudaSlice<f32>,
+    pub attn_q_d: CudaSlice<f32>,
+    pub heads_w_gate_d: CudaSlice<f32>,
+    pub heads_b_gate_d: CudaSlice<f32>,
+    pub heads_w_main_d: CudaSlice<f32>,
+    pub heads_b_main_d: CudaSlice<f32>,
+    pub heads_w_skip_d: CudaSlice<f32>,
+    pub heads_b_skip_d: CudaSlice<f32>,
+
     // Ping-pong hidden state
     h_ping: CudaSlice<f32>,
     h_pong: CudaSlice<f32>,
@@ -191,6 +220,36 @@ impl CfcTrunk {
             snap_feat_d: stream.alloc_zeros::<f32>(FEATURE_DIM).context("snap_feat alloc")?,
             probs_d: stream.alloc_zeros::<f32>(N_HORIZONS).context("probs alloc")?,
             proj_out_d: stream.alloc_zeros::<f32>(PROJ_DIM).context("proj_out alloc")?,
+            // === V2 skeleton fields (X1) — allocated BEFORE `stream` is
+            // moved into the struct below. Populated by X2..X9. ===
+            vsn_w_d: stream.alloc_zeros::<f32>(cfg.n_in * cfg.n_in)
+                .context("v2 vsn_w alloc")?,
+            vsn_b_d: stream.alloc_zeros::<f32>(cfg.n_in)
+                .context("v2 vsn_b alloc")?,
+            mamba2_stack_1: None,
+            mamba2_stack_2: None,
+            ln_a_gain_d: stream.alloc_zeros::<f32>(cfg.n_hid)
+                .context("v2 ln_a_gain alloc")?,
+            ln_a_bias_d: stream.alloc_zeros::<f32>(cfg.n_hid)
+                .context("v2 ln_a_bias alloc")?,
+            ln_b_gain_d: stream.alloc_zeros::<f32>(cfg.n_hid)
+                .context("v2 ln_b_gain alloc")?,
+            ln_b_bias_d: stream.alloc_zeros::<f32>(cfg.n_hid)
+                .context("v2 ln_b_bias alloc")?,
+            attn_q_d: stream.alloc_zeros::<f32>(cfg.n_hid)
+                .context("v2 attn_q alloc")?,
+            heads_w_gate_d: stream.alloc_zeros::<f32>(N_HORIZONS * HEAD_MID_DIM)
+                .context("v2 heads_w_gate alloc")?,
+            heads_b_gate_d: stream.alloc_zeros::<f32>(N_HORIZONS)
+                .context("v2 heads_b_gate alloc")?,
+            heads_w_main_d: stream.alloc_zeros::<f32>(N_HORIZONS * HEAD_MID_DIM)
+                .context("v2 heads_w_main alloc")?,
+            heads_b_main_d: stream.alloc_zeros::<f32>(N_HORIZONS)
+                .context("v2 heads_b_main alloc")?,
+            heads_w_skip_d: stream.alloc_zeros::<f32>(N_HORIZONS * cfg.n_hid)
+                .context("v2 heads_w_skip alloc")?,
+            heads_b_skip_d: stream.alloc_zeros::<f32>(N_HORIZONS)
+                .context("v2 heads_b_skip alloc")?,
             stream,
             _snap_module: snap_module,
             _step_module: step_module,