CE64 ISA: strict decoder, register methods, field contracts

.claude/board/entries/2026-10-08-ce64-isa-register-contract.md

@@ -0,0 +1,93 @@
+# 2026-10-08 — CE64 ISA: strict decoder, register methods, field contracts
+
+**Status:** TEST-PINNED. Reasoning chooses the operation; `CausalEdge64`
+defines what that operation means.
+
+Code: `crates/causal-edge/src/isa.rs` (new), `edge.rs`, `syllogism.rs`,
+`network.rs`. Tests: `crates/causal-edge/tests/ce64_isa_contract.rs`,
+`ce64_isa_golden.rs` (+ `ce64_legacy_capture.txt`), `ce64_op_contract.rs`;
+`crates/lance-graph-planner/tests/gadamer_isa_revision.rs`; the MooreNars16
+probe (#1406) now compares `Result`s and draws executable inference codes.
+
+## What changed
+
+- **Strict decoder.** Of the 16 inference codes, exactly `+1` Deduction,
+  `+2` Induction, `-1` Abduction, `+4` Revision, `+5` Synthesis execute
+  (`Opcode::decode`). The other 11 (`0`, `-8`, `-2`, `±3`, `-4`, `-5`,
+  `±6`, `±7`) return `IsaFault::Unsupported { mantissa }`. Before, `±6` and
+  `±7` ran the Synthesis mean and came back stamped `±6` and `7`; `0`, `-8`,
+  `-2`, `±3`, `-4`, `-5` ran another instruction and came back stamped with
+  that instruction's code.
+- **`forward` only dispatches**: decode, then `execute(op, ..)`. It now
+  returns `Result`; so do `forward_chain`, `NarsEngine::forward_edge` and
+  `replay_step` (`ReplayError::Isa`).
+- **Register methods**: `deduction`, `induction`, `abduction`, `synthesis`
+  take an explicit `Compose` (S/P/O payload algebra) and return `Self`;
+  `revision(rhs)` is truth-only (writes F, C; keeps every other field of
+  `self`; no `Compose`); `counterfactual` and `intervention` are partial and
+  always refuse.
+- **One truth function per instruction** (`isa::truth`); `forward`, `learn`
+  and `syllogize` delegate. The three previous copies are gone.
+- **Field contracts** (`isa::contracts`): reads / computes / passes /
+  constants, payload algebra, failure condition, measured by perturbation in
+  `ce64_isa_contract.rs`.
+
+## Field-liveness matrix
+
+| instruction | computes | passes through | constant | Compose | fails |
+|---|---|---|---|---|---|
+| forward / `execute` | S/P/O, F, C, Pearl (AND) | inference ← B, Direction ← B, Plasticity ← B | W = 0, Epi5 = 0 | yes | B's code has no implementation |
+| `revision` | F, C | everything else ← A | — | no | never |
+| `learn` | S/P/O, F, C, Plasticity | Pearl, Direction, inference, W, Epi5 ← A | — | no | never |
+| `syllogize` | S/P/O, F, C, Pearl, inference | — | Direction 0, Plasticity 0b111, W 0, Epi5 0 | no | `None` without a figure |
+
+The W/Epi5 zeroing in `forward` and `syllogize` is legacy behaviour, now
+DECLARED, not changed.
+
+## Golden vectors
+
+- Legacy capture: 126 raw-word vectors recorded from the pre-ISA code. 71
+  reproduce bit for bit; the 55 whose weight carries an unsupported code
+  now refuse with that code. Nothing else moved.
+- Normative: 23 forward vectors through the named methods, checked against
+  an independent f64 reference (±1 on F/C) and the declared contract.
+
+## The max-confidence revision defect (not normative)
+
+`revision(c=255, c=255)` returns `f = c = 0`, in `forward`, `revision` and
+`learn`. Path: `c = 1.0 >= 0.999` → `evidence_weight = f32::MAX` for both →
+`ws = MAX + MAX = +inf` → `f = inf/inf = NaN`, `c = NaN` → the float-to-u8
+cast saturates NaN to 0. Not a u8 overflow, LUT bin, or zero-denominator
+fallback. Also: ONE operand at 255 is finite but dominates (its weight is
+`f32::MAX`), where the capped reference gives a weighted mean. Both kept
+out of the normative set and pinned.
+
+## Gadamer stays above
+
+`GadamerRevision` decides whether evidence is admitted; `revision` only
+computes. Ten echo or closed-cycle encounters leave confidence unchanged
+because the gate never calls the register; ten new roots raise it. The
+register alone would inflate an echo (pinned).
+
+## Disable runs (anchor asserted, each red)
+
+CF decoded as Synthesis (6 tests) · forward ignores the decoded op (4) ·
+learn clears W (4) · revision clears Epi5 (1) · diverging revision formula
+(4) · known-bad promoted to normative (2) · a policy type named in `isa.rs`
+(1) · `counterfactual` computes (1) · Gadamer gate bypassed (2).
+
+## OPEN
+
+- `forward`'s revision step (+4) composes payload; `revision(rhs)` does
+  not. Whether a payload-composing revision step should exist is a
+  decision, not made here.
+- The c = 255 saturation rule (collapse and dominance). Smallest fix: cap
+  `c` before `evidence_weight` as the f64 reference does.
+- `forward` writes the executed code into the result's bits 46..49. The
+  transition-loop reading ("do not whisper the operation back into the
+  result edge") says it should not. Pre-existing; not changed here.
+- `learn` mixes arithmetic (revision) with policy (archetype reassignment,
+  freeze thresholds 0.9 / 0.7). Named split, not done.
+- `syllogize` chooses the rule from the figure (a choice) and computes it.
+- Planner truth copies outside the CE64 register (`TruthValue`,
+  `nars_infer`, `NarsTables`) still differ; out of scope.

.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.
 
-268 entries, 2026-08-06 .. 2026-10-08.
+269 entries, 2026-08-06 .. 2026-10-08.
 
 | date | entry id | finding | file |
 |---|---|---|---|
@@ -35,6 +35,7 @@ exactly one of them, never both.
 | 2026-10-08 | `moore-nars16-isa-visible-representation` |  | [2026-10-08-moore-nars16-isa-visible-representation.md](2026-10-08-moore-nars16-isa-visible-representation.md) |
 | 2026-10-08 | `D-MOORE-NARS-0` |  | [2026-10-08-moore-nars-0-recipe-learning-gomoku.md](2026-10-08-moore-nars-0-recipe-learning-gomoku.md) |
 | 2026-10-08 | `coresearch-ce64-moore-masking-wiring` |  | [2026-10-08-coresearch-ce64-moore-masking-wiring.md](2026-10-08-coresearch-ce64-moore-masking-wiring.md) |
+| 2026-10-08 | `ce64-isa-register-contract` |  | [2026-10-08-ce64-isa-register-contract.md](2026-10-08-ce64-isa-register-contract.md) |
 | 2026-10-07 | `tinker-janus-fold-harvest` | TinkerPop bulk = K (GroupReduce), ONE_BULK = S, GValue pinning = bundle invalidation; JanusGraph slice = OrderedLaneWitness→Range (30–38×); no new V4 op | [2026-10-07-tinker-janus-fold-harvest.md](2026-10-07-tinker-janus-fold-harvest.md) |
 | 2026-10-07 | `selector-seq-aware-coverage` |  | [2026-10-07-selector-seq-aware-coverage.md](2026-10-07-selector-seq-aware-coverage.md) |
 | 2026-10-07 | `D-PUZZLE-ATTN-0` |  | [2026-10-07-puzzle-attn-0-entropy-attention-crosswords.md](2026-10-07-puzzle-attn-0-entropy-attention-crosswords.md) |