coding-practices: add SoA patterns + mandatory simd::* + 3-way BindSpace merge + adhering-agent review checklist

Four additions to .claude/CODING_PRACTICES.md — extends the existing
EmbedAnything-patterns content with the SoA / object-does-the-work /
substrate-level patterns that crystallized during the codec-sweep
lab-infra session (PRs #225–#239).

1. SoA + Object-Does-The-Work Patterns (~100 lines)
   - Checklist for new DTOs / kernels / caches: sealed builders,
     stable signatures excluding drift, typed errors, Cache<H>
     generic-over-handle, stub flag for Phase-N-before-Phase-N+k,
     feature matrix tested, serialisation at edges, DoS ceilings
     at construction not enumeration
   - Five additional anti-patterns (6-10) surfaced by session
     corrections: stateless-shader vs stateful-engine misframed,
     hallucinating ndarray surface, feature-matrix blindness,
     epiphany-dumping orientation-as-discovery, raw struct literals
     bypassing builders
   - 10 shipped-pattern reference entries citing the actual files
     + test counts
   - 8 principles: object does the work, SoA over AoS, same-
     substrate-different-view, Stream/Resonance/Bus lifecycle,
     weights are seeds, scaffold-before-codegen, feature matrix
     is part of contract, pin your toolchain
   - Read order for new sessions

2. MANDATORY: `ndarray::simd::*` canonical import (new section)
   - Correct/wrong examples per Rule B + invariant I2
   - AMX sibling module + tile primitives + simd_caps canonical
     paths
   - Polyfill hierarchy (Tier 1 AMX → Tier 4 AVX-2, no consumer
     scalar tier)
   - Reviewer trigger for `std::arch::*` or
     `ndarray::hpc::simd_avxNNN::*` reach

3. 3-Way BindSpace Mutation Scheme (new section)
   - Table: Xor (single-writer reversible) / Bundle (multi-writer
     saturating, E-SUBSTRATE-1 guaranteed associative in
     expectation) / Superposition (preserve ambiguity)
   - When to use each + explicit DON'T-INTERCHANGE rule
   - Iron rule citation (CLAUDE.md I-SUBSTRATE-MARKOV): Xor on
     multi-writer path breaks the Markov guarantee
   - Reviewer trigger for Xor on concurrent-writer paths

4. Adhering-Agent Review Checklist (new section)
   - Per-agent table mapping 18 specialist agents + 5 meta-agents
     to the specific checklist sections they own
   - Spawn pattern: hand PR scope to 1-2 matching agents with
     pointer to this doc; they walk their rubric and return
     PASS/FAIL with specific line citations
   - Agents READ this doc as their rubric, not their personality

The doc is now both the author-side pattern guide AND the
reviewer-side checklist. Specialist agents adhere to it; PRs are
reviewed against it; new sessions load it as part of the mandatory
pre-read set.

Cross-ref: CLAUDE.md I-SUBSTRATE-MARKOV + I-NOISE-FLOOR-JIRAK;
lab-vs-canonical-surface.md invariants I1-I11 + six rules A-F;
cognitive-shader-architecture.md 7-layer stack + SoA column types;
ripple-dto-contracts.md Stream/Resonance/Bus/ThoughtStruct lifecycle;
this session's PRs #225-#239 shipping the SoA patterns in practice.

https://claude.ai/code/session_01SbYsmmbPf9YQuYbHZN52Zh

Author: claude