jc: DAV probe carrier invariance — Quack carrier (R1) + resident bit-plane carrier (R2)

.claude/board/entries/2026-10-06-dav-carrier-invariance-quack.md

@@ -0,0 +1,36 @@
+# 2026-10-06 — DAV active-observation probe: carrier invariance under Quack (Round 1)
+
+## MEASURED
+
+`crates/jc/examples/dav_active_observation_probe.rs` (`carrier_differential`)
+runs the #1344 world through two carriers:
+
+- A: `[Option<bool>; N]` (the #1344 reference);
+- B: value lane (`LaneRef::U32`) + validity plane, the plane being the
+  horizon's own `independent_roots` word, borrowed with `slice::from_ref`.
+
+Candidate selection in B is one Quack filter, `is_null(VALID) AND
+Cmp::Range(SITE)`, lowered by `lance_graph_quack::lower` and executed by
+`lance_graph_mask_risc::execute_into` (`Terminal::Keep`). Routes, scoring and
+revision are shared code (`trait Observed`).
+
+Equal across 5 apertures × 4 NULL payloads (zero, hidden truth, its
+negation, garbage) × 2 enumeration orders: candidate ids, disagreement, EWA
+weight, score (bit-exact), order; and, for the DAV and ordinal cycles:
+pre-observation disagreement, `RevisionDelta` (kind, effect, resulting),
+post-replay disagreement, residual, final observed/value state.
+
+Disable runs, each red: frontier bound to the nullable `VALUE` column (the
+`sql_where` silence assert fires); reader passes NULL payload through (A≠B
+under the truth payload); leaky twin made non-leaky (the can-fire assert);
+ordinal tie-break dropped (the existing #1344 order check fires first);
+frontier `hi` off by one.
+
+## OPEN
+
+- `Cmp::Range`'s provenance `Col` (`SITE`) names no resident lane: the
+  ordinal axis has no lane, and `Pred::Range` reads none. It is minted by
+  hand here, not through `Filter::prefix_facet` + `OrderedLaneWitness`.
+- Copies on the B path: the `u32` value lane (N from `projected_claims`),
+  the kept mask (`words_for(N)`), `Scratch::for_program`, the set-bit
+  `Vec<usize>`, the `Vec<Candidate>`. Round 2 audits these.

.claude/board/entries/2026-10-06-dav-resident-reading-round2.md

@@ -0,0 +1,53 @@
+# 2026-10-06 — DAV probe: resident bit-plane carrier, population boundary (Round 2)
+
+## MEASURED
+
+Carrier C in `crates/jc/examples/dav_active_observation_probe.rs`
+(`resident_differential`) reads the horizon's `independent_roots` (validity)
+and `projected_claims` (value) as two borrowed `&[u64]` planes. It builds no
+value lane. A == B == C over 5 apertures × 4 poisons × 2 orders, covering
+candidate ids, disagreement, EWA weight, score and ranking. The DAV and
+ordinal cycles also match: delta, resulting horizon, replay, residual and
+final state. Poison for C sets `projected_claims` at unobserved sites.
+
+C has no SQL NULL semantics (a plane is never nullable to Quack). B stays the
+NULL test.
+
+k = 1 is a streaming fold over the kept mask (`top1_fold`, state one
+`Option<Candidate>`). It matches A's `ranked[0]` everywhere. The ordinal
+pick is the lowest set bit.
+
+Heap @ a=0.55, 2 candidates, plans lowered outside the window:
+- C candidate selection + visitation: 0 B
+- C streaming top-1: 8 B = 2 × 4 B, from `jc::quorum::pairwise_agreement_u8`'s
+  result `Vec`, which is route semantics and unchanged
+- C full rank: 586 B; B full rank: 762 B
+
+Derived population bytes on C: the kept mask, 8 B, a caller-owned stack
+array. `stay-on-the-lane.md` §6 counts that as materialization. The candidate
+program's lowering is `Tiled`; no fused lowering keeps membership without
+writing it.
+
+Disable runs, each red: leaky gate (projected bit at an unobserved site read
+as observed-true); C selecting on the value plane; one value bit flipped; the
+fold's tie-break dropped; the validity gate removed; a `Vec` row-id list in
+the selection window; the tie-break can-fire made vacuous.
+
+Inverting EVERY value bit leaves ranking unchanged. The route disagreement is
+symmetric under a global flip, so only the final-state check catches it.
+
+## FINDING
+
+No shipped terminal returns a position. The list ends at Count/Any/All/
+Masked{Sum,Min,Max}I32/Keep/Scatter*/CountKeyRuns/Group*.
+`MaskedMaxI32` returns a value, not its row. The DAV score is not a lane
+either: it is per-site route semantics in Rust. So top-1 in mask-risc would
+need two things. One is a masked argmax with an ordinal tie-break, over a lane
+whose order matches the score order exactly. The other is the score as a
+lane, which would be a population-sized derived lane. Neither is built.
+
+## OPEN
+
+- The kept mask is the first population object. Visiting it needs
+  membership out of mask-risc. No fused lowering hands a word to a consumer
+  visitor without a `Keep` write.

.claude/board/entries/README.md

@@ -25,10 +25,12 @@ 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.
 
-219 entries, 2026-08-06 .. 2026-10-05.
+221 entries, 2026-08-06 .. 2026-10-06.
 
 | date | entry id | finding | file |
 |---|---|---|---|
+| 2026-10-06 | `dav-resident-reading-round2` |  | [2026-10-06-dav-resident-reading-round2.md](2026-10-06-dav-resident-reading-round2.md) |
+| 2026-10-06 | `dav-carrier-invariance-quack` |  | [2026-10-06-dav-carrier-invariance-quack.md](2026-10-06-dav-carrier-invariance-quack.md) |
 | 2026-10-05 | `text-to-numeric-boundary-inventory` |  | [2026-10-05-text-to-numeric-boundary-inventory.md](2026-10-05-text-to-numeric-boundary-inventory.md) |
 | 2026-10-05 | `report-pair-key-and-stack-recon` |  | [2026-10-05-report-pair-key-and-stack-recon.md](2026-10-05-report-pair-key-and-stack-recon.md) |
 | 2026-10-05 | `quack-two-world-frontend` |  | [2026-10-05-quack-two-world-frontend.md](2026-10-05-quack-two-world-frontend.md) |

crates/jc/Cargo.toml

@@ -37,6 +37,11 @@ lance-graph-contract = { path = "../lance-graph-contract" }
 # neural-debug runtime registry. Dev-deps: examples only, not the library.
 p64 = { path = "../../../ndarray/crates/p64" }
 neural-debug = { path = "../neural-debug" }
+# `dav_active_observation_probe` only — the Round-1 carrier differential runs
+# the probe's candidate selection as a Quack filter over a value lane +
+# validity plane, executed by the one mask-risc evaluator.
+lance-graph-quack = { path = "../lance-graph-quack" }
+lance-graph-mask-risc = { path = "../lance-graph-mask-risc" }
 
 [[example]]
 # A0/A1/A2 Goursat probe (TD-PILLAR11-SCIENTIFIC-LOOPS-BYPASS-NDARRAY-SIMD-1).