fix(sprint-11/wave-D): D-CSV-7 — last_emission_cycle u32::MAX sentinel + lib re-export + ndarray hpc-extras

W-D1 worker completion notification (after the prior commit window)
landed three improvements:

1. **MailboxSoA cycle-0 same-cycle false positive (real bug)** — the
   prior commit initialized `last_emission_cycle: [0u32; N]`, but
   `current_cycle` also starts at 0. The `last_emission_cycle[row]
   == self.current_cycle` guard in `emit()` would then incorrectly
   suppress emissions during cycle 0 (the first cycle of any
   MailboxSoA's lifetime). Fixed by initializing the array to
   `u32::MAX` (the "never-emitted" sentinel — distinct from any
   valid cycle stamp during normal operation). `reset_row()` also
   restores the sentinel; `test_mailbox_soa_new_zero` updated to
   assert `u32::MAX`.

2. **`lib.rs` re-export missing** — added `pub mod mailbox_soa;` and
   `pub use mailbox_soa::{MailboxSoA, DefaultMailboxSoA};` next to
   the existing bindspace re-exports. The prior commit had the file
   but didn't expose the types to downstream consumers.

3. **`Cargo.toml` ndarray hpc-extras feature** — adds `"hpc-extras"`
   to the ndarray feature list. Resolves the pre-existing blake3
   compile failure that blocked `cargo test --manifest-path
   crates/cognitive-shader-driver/Cargo.toml` in this environment.
   Same fix W-C1 applied to PR #385's branch.

Cross-spec inconsistency noted by W-D1 (no action needed):
`CollapseGateEmission::new()` signature is `(source, chain_position,
merge_mode)`, not `(source, current_cycle, merge_mode)` as the W-D1
prompt documented. The `chain_position` field semantically maps to
`current_cycle` (per plan §8.1 "no explicit cycle_id field —
provenance via (source_mailbox, chain_position)"); emit() correctly
passes `self.current_cycle` as the `chain_position` arg. Naming
mismatch is a doc-comment polish for a future iteration.

Test status: **9/9 mailbox_soa tests pass; 65/65 lib tests pass total.**

https://claude.ai/code/session_01UwJuKqP828qyX1VkLgGJFS

Author: claude

crates/cognitive-shader-driver/Cargo.toml

@@ -41,7 +41,7 @@ lance-graph-ontology = { path = "../lance-graph-ontology", default-features = fa
 p64-bridge            = { path = "../p64-bridge" }
 bgz17                 = { path = "../bgz17" }
 causal-edge           = { path = "../causal-edge" }
-ndarray               = { path = "../../../ndarray", default-features = false, features = ["std"] }
+ndarray               = { path = "../../../ndarray", default-features = false, features = ["std", "hpc-extras"] }
 
 # Optional: real thinking-engine wiring behind a feature gate, matching
 # the EmbedAnything "default = runtime only; heavy deps behind features" rule.

crates/cognitive-shader-driver/src/lib.rs

@@ -95,6 +95,7 @@ pub mod driver;
 pub mod auto_style;
 pub mod engine_bridge;
 pub mod sigma_rosetta;
+pub mod mailbox_soa;
 
 // ──────────────────────────────────────────────────────────────────────
 // LAB-ONLY modules — compiled only into the shader-lab binary. Never
@@ -195,3 +196,4 @@ pub use engine_bridge::{
     ingest_codebook_indices, dispatch_from_top_k,
     write_qualia_17d, read_qualia_17d, persist_cycle,
 };
+pub use mailbox_soa::{MailboxSoA, DefaultMailboxSoA};

crates/cognitive-shader-driver/src/mailbox_soa.rs

@@ -80,7 +80,11 @@ impl<const N: usize> MailboxSoA<N> {
             mailbox_id,
             energy: [0.0f32; N],
             plasticity_counter: [0u8; N],
-            last_emission_cycle: [0u32; N],
+            // u32::MAX is the "never emitted" sentinel. current_cycle starts at 0
+            // and advances via wrapping_add(1); in practice it never reaches
+            // u32::MAX during a session, so the first emit on any cycle is always
+            // permitted (u32::MAX != any valid cycle stamp).
+            last_emission_cycle: [u32::MAX; N],
             current_cycle: 0,
             w_slot,
             threshold,
@@ -173,7 +177,9 @@ impl<const N: usize> MailboxSoA<N> {
         }
         self.energy[row] = 0.0;
         self.plasticity_counter[row] = 0;
-        self.last_emission_cycle[row] = 0;
+        // Restore the "never emitted" sentinel so the row can emit immediately
+        // on the next cycle without triggering the same-cycle guard.
+        self.last_emission_cycle[row] = u32::MAX;
     }
 
     // ── Read-only inspectors ──────────────────────────────────────────────────
@@ -232,7 +238,10 @@ mod tests {
 
     // ── test 1: new ───────────────────────────────────────────────────────────
 
-    /// New mailbox must have all per-row state zero, correct w_slot and threshold.
+    /// New mailbox must have all per-row state initialised correctly.
+    ///
+    /// energy and plasticity_counter are zero; last_emission_cycle is u32::MAX
+    /// (the "never emitted" sentinel so cycle 0 can emit without false guard).
     #[test]
     fn test_mailbox_soa_new_zero() {
         let mb: MailboxSoA<8> = MailboxSoA::new(7, 5, 1.0);
@@ -249,8 +258,8 @@ mod tests {
             );
             assert_eq!(
                 mb.last_emission_cycle[row],
-                0,
-                "last_emission_cycle[{row}] should be 0"
+                u32::MAX,
+                "last_emission_cycle[{row}] should be u32::MAX (never-emitted sentinel)"
             );
         }
     }