cognitive-shader-driver: dispatch stops materializing O(rows²); one SPOFC candidate per row

.claude/board/SUPERSESSION-INDEX.md

@@ -14,7 +14,7 @@
 ## What this table says
 
 **`BindSpace` is the shape of the problem.** Marked RETIRE, and simultaneously the
-most-referenced symbol here: **68 crate files, 48 plans, 42 of them blind.**
+most-referenced symbol here: **69 crate files, 48 plans, 42 of them blind.**
 That is a programme, not a cleanup.
 
 **`GateState` is the sharpest case: 1 plan names it and *every one* is blind.**
@@ -60,7 +60,7 @@ coverage instead.
 | `GateState` | REPURPOSE | — | 14 | 1 | 1 |
 | `MergeMode` | REPURPOSE | — | 8 | 14 | 13 |
 | `ResonanceDto` | REPURPOSE | `PerturbationDto` | 2 | 12 | 7 |
-| `BindSpace` | RETIRE | — | 68 | 48 | 42 |
+| `BindSpace` | RETIRE | — | 69 | 48 | 42 |
 | `CollapseGateEmission` | RETIRE | — | 5 | 14 | 12 |
 | `ThinkingStyle` | RETIRE-toward-contract | — | 52 | 28 | 24 |
 

.claude/board/entries/2026-09-25-dispatch-materialization-trace.md

@@ -0,0 +1,39 @@
+# 2026-09-25 — One shader dispatch materialized O(rows²) to return at most 8 hits
+
+**Status:** MEASURED · DONE (two collections removed, output digest unchanged; duplicate candidate slots replaced by one SPOFC candidate per row, #1293) · OPEN (the prefilter row list; writing SPOFC into CE64)
+
+## The measurement (`crates/cognitive-shader-driver/tests/dispatch_trace.rs`)
+A counting global allocator measures one `ShaderDriver::dispatch`, after a warm-up, at 16..256 rows. The driver's module doc claims "no allocations beyond top-k + edges".
+
+| rows | before | after |
+|---|---|---|
+| 16 | 23 KB, 44 allocs | 1.2 KB, 5 allocs |
+| 256 | 5.3 MB, 530 allocs | 2.2 KB, 5 allocs |
+
+Before, bytes grew with the square of the population and allocations grew linearly. The answer is at most 8 hits either way (`hit_count` is taken after the cut to 8).
+
+## What was materialized and discarded
+- **Content pre-pass.** It pushed two hits per resonant pair into a `Vec` (O(rows²)), then stable-sorted the Vec and cut it to 8. `TopHits` now keeps the best 8 as they arrive. A new hit goes after every kept hit whose resonance is not lower, so ties keep arrival order exactly as the stable sort did.
+- **`p64-bridge` `cascade`.** It returned every candidate (up to 256 per row) in a fresh `Vec`, sorted, of which the driver read 4. `cascade_nearest::<K>` keeps the K nearest, allocation-free. Both methods share one private candidate walk.
+
+## Evidence it is the same computation
+- **Digest.** A hash over every field of the crystal (60 configurations × 3 dispatches: rows 16..300, radii 50..MAX, `Auto` + `Ordinal` 0/5/11) is identical before and after (`355d5fccbc424763`).
+- **Equivalence tests.** `TopHits` and `cascade_nearest` each have a test against the collect-sort-truncate they replace, on tie-heavy inputs.
+- **Disable runs.** Restoring either collection breaks the pinned constant allocation count (37 → 69, 12 → 14).
+
+## Open
+- **The row list.** `passed_rows` (4 bytes per surviving row) is the prefilter's population materialized as a list of row ids. Replacing it with a mask is the natural next step, but it changes `BackingStore::prefilter`'s shape.
+- **The rest of the trace.** Stage [4] rotates each hit's row by its `cycle_index` before the XOR, so each hit contributes in its own basis. That is the relative-coordinate step of the end-to-end chain, and it has not yet been traced as such.
+
+## The `cycle_index` trace found a cancellation (#1293)
+Stage [4] builds `cycle_fp = XOR over hits of R^{cycle_index} · row`. Stage [3] offered every supporting relationship (each content pair, each P64 cascade hit) as its own slot, and a row's `cycle_index` is its position, so one row supported N ways gave N identical terms. XOR cancels pairs: on empty predicate planes, 36 of 60 dispatches had a repeated row in top-k, and in some the strongest row vanished from `cycle_fp` entirely.
+
+**Fix.** One candidate per surviving row. Its relationships aggregate into a SPOFC record (driver-private; the only code precedent is arm-discovery's `CandidateTriple`/`TruthU8`): predicate union, best-resonance partner as object (`Row` or P64 `Palette` target), support count `m`, and `TruthU8 { f = best resonance, c = m·255/(m+k) }` via `evidence_confidence_u8`, extracted from `arm_to_truth_u8` so both share one convention.
+
+**Effect, 60 dispatches each, old vs new.** Non-empty planes: `cycle_fp` changed in 12, edges and top-k in 60. Empty planes: 48, 48, 48; repeated rows 36 → 0. Disabling only the predicate union drops the non-empty edge change to 12, so 48 of those edge changes are the union's `CausalMask` bits. The digest above is therefore intentionally not preserved by this change.
+
+**Allocation.** One more allocation (the candidate table, 6 total), still constant in rows; bytes grow 28 per surviving row (4 row id + 24 SPOFC). `dispatch_trace` pins both.
+
+**Falsifiers, each disable-verified:** re-offering each relationship → the braid test fails; not counting support → both SPOFC evidence tests fail; dropping or overwriting the union → the union test fails (it had no falsifier before; all 111 lib tests stayed green without it).
+
+**Not done here.** The SPOFC record ends at a `debug_assert`: the emitted CE64 still packs `s = row%256, p = 0, o = (row/4)%256`, `f = c = resonance`. CE64's 24-bit S/P/O could hold the target (palette256³); the driver does not write it. That, and carrying the evidence across cycles without recounting it, is the follow-up.

.claude/board/entries/README.md

@@ -25,7 +25,7 @@ index row, (3) no duplicate entry id. Checks 1 and 2 are deliberately
 opposite directions; the stranding this convention prevents shows up in
 exactly one of them, never both.
 
-174 entries, 2026-08-06 .. 2026-09-25.
+175 entries, 2026-08-06 .. 2026-09-25.
 
 | date | entry id | finding | file |
 |---|---|---|---|
@@ -39,6 +39,7 @@ exactly one of them, never both.
 | 2026-09-25 | `lance12-lancedb039-sweep` |  | [2026-09-25-lance12-lancedb039-sweep.md](2026-09-25-lance12-lancedb039-sweep.md) |
 | 2026-09-25 | `keep-fold` |  | [2026-09-25-keep-fold.md](2026-09-25-keep-fold.md) |
 | 2026-09-25 | `hhtl-ordered-access` |  | [2026-09-25-hhtl-ordered-access.md](2026-09-25-hhtl-ordered-access.md) |
+| 2026-09-25 | `dispatch-materialization-trace` |  | [2026-09-25-dispatch-materialization-trace.md](2026-09-25-dispatch-materialization-trace.md) |
 | 2026-09-25 | `argon2-in-register-compress-per-tier` |  | [2026-09-25-argon2-in-register-compress-per-tier.md](2026-09-25-argon2-in-register-compress-per-tier.md) |
 | 2026-09-25 | `aperture-prefix-lowers-to-range` |  | [2026-09-25-aperture-prefix-lowers-to-range.md](2026-09-25-aperture-prefix-lowers-to-range.md) |
 | 2026-09-25 | `aperture-masks-and-kernel-gap` |  | [2026-09-25-aperture-masks-and-kernel-gap.md](2026-09-25-aperture-masks-and-kernel-gap.md) |

crates/cognitive-shader-driver/Cargo.toml

@@ -41,6 +41,9 @@ lance-graph-ontology = { path = "../lance-graph-ontology", default-features = fa
 p64-bridge            = { path = "../p64-bridge" }
 bgz17                 = { path = "../bgz17" }
 causal-edge           = { path = "../causal-edge" }
+# SPOFC truth (`TruthU8`, the evidence-confidence convention). Zero-dependency
+# with default features.
+lance-graph-arm-discovery = { path = "../lance-graph-arm-discovery" }
 ndarray               = { path = "../../../ndarray", default-features = false, features = ["std", "hpc-extras"] }
 
 # Optional: real thinking-engine wiring behind a feature gate, matching