docs(slice-2b): Phase 1.6+ Slice 2b investigation report v0.0.12

WASM_BINARY integration canonical bloqueado por structural Cargo + WASM stdlib
alloc conflict canonical. 4 fix attempts NO solved. Larihana Slice 2c handoff
diary filed.

## Error canonical empírico
duplicate lang item exchange_malloc canonical entre:
- rustup precompiled liballoc-***.rlib (wasm32 target)
- wbuild recompiled liballoc-***.rmeta (panic=abort triggered rebuild)

## 4 fix attempts registered
1. Remove direct serde dep (upstream pattern) — NO solved
2. Pin serde =1.0.219, =1.0.217 — NO solved (frame-support requires ^1.0.217)
3. Remove profile.release lto customization — NO solved
4. WasmBuilder::build_using_defaults() upstream — NO solved

## Root cause empírico
wbuild auto-genera profile.release con panic=abort → Cargo recompila alloc
desde rust-src component → conflict con precompiled rustup alloc rlib.

## Handoff canonical a Larihana Slice 2c
Diary canonical filed requesting Plan C Rust ports expertise canonical:
- cargo workspace.metadata.wasm-builder section?
- SKIP_WASM_BUILD=1 fallback + pre-built WASM file pattern?
- rust-src component interaction con substrate-wasm-builder?
- RUSTFLAGS -Z build-std=core,alloc nightly approach viable?
- Upstream paritytech/polkadot-sdk known issue?

## State canonical preserved post-revert
- substrate-wasm-builder workspace dep declared pero NO activa
- build.rs no-op canonical mientras Slice 2c land
- Doc extensivo en lib.rs registering investigation + handoff
- origin-chain-types no_std refactor v0.0.11 preserved canonical
- origin-chain-node binary 4 subcommands operativos

## Temporal workaround canonical
chain_spec.rs Phase 1.6+ Slice 3 puede continue con mock-WASM fallback
mientras Slice 2c land canonical.

## Filosofía canonical
David canon 2026-05-14 "la libertad infinita acota solo donde empieza la del
otro" — honest decisión canonical de pedir Larihana expertise mejor que
stuck attempts. El barquero pide guía al hyperport builder cuando el río
demanda profundidad técnica que no posee solo.

## Build
- cargo build --release 34.44s post-revert clean
- No regression desde v0.0.11

Phase 1.6+ progress:
- Slice 1 ✅ + Slice 2 ✅
- Slice 2b 📋 investigation report + Larihana diary (esta v0.0.12)
- Slice 2c ⏳ WASM_BINARY post Larihana expertise
- Slice 3 ⏳ + Slice 4 ⏳

Refs: CHARON_ROADMAP_V1 Phase 1.6+ Slice 2b investigation, Larihana diary
WASM_BUILD_BLOCKER_REQUEST_LARIHANA_SUBSTRATE_EXPERTISE_SLICE_2C canonical

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

crates/origin-chain-runtime/Cargo.toml

@@ -57,16 +57,25 @@ scale-info.workspace = true
 # Logging
 log.workspace = true
 
-# Serialization
-serde = { workspace = true, optional = true }
+# Serialization canonical — Slice 2b finding: solochain-template upstream NO
+# declara serde directly canonical. Solo serde_json. Serde viene transitive
+# from FRAME pallets canonical (frame-support + frame-system). Direct serde
+# dep rompía isolated WASM build canonical.
 serde_json.workspace = true
 
 [build-dependencies]
-# Slice 2 v0.0.11 retry: substrate-wasm-builder DEFERRED nuevamente — serde 1.0.x
-# alloc/serde_core feature conflicts canonical con substrate-wasm-builder isolated
-# WASM build canonical (duplicate `exchange_malloc` lang item canonical entre
-# rustup stdlib alloc + wbuild dir alloc canonical). Investigation canonical:
-# requires deep Rust toolchain debugging — Slice 2b dedicated.
+# Slice 2b investigation registered canonical 2026-05-21: 4 fix attempts canonical:
+#   1. Remove direct serde dep (transitive from FRAME) — NO solved
+#   2. Pin serde =1.0.219 + =1.0.217 — NO solved
+#   3. Remove profile.release lto/codegen-units customization — NO solved
+#   4. WasmBuilder::build_using_defaults() (upstream pattern) — NO solved
+#
+# Root cause empírico: wbuild compila su propio alloc canonical con panic=abort
+# pero la precompiled rustup alloc canonical para wasm32 también está linked.
+# Conflict canonical es duplicate exchange_malloc lang item canonical.
+#
+# Slice 2c canonical requires Larihana Substrate-adjacent expertise canonical
+# (Plan C Rust ports + WASM workspace canonical experience) — diary filed.
 # substrate-wasm-builder = { workspace = true, optional = true }
 
 [features]
@@ -101,8 +110,7 @@ std = [
     "pallet-transaction-payment-rpc-runtime-api/std",
     "parity-scale-codec/std",
     "scale-info/std",
-    "serde",
-    # "substrate-wasm-builder",  # DEFERRED Slice 2b debugging canonical
+    # Slice 2c canonical deferred — substrate-wasm-builder bloqueado WASM build
 ]
 runtime-benchmarks = [
     "frame-system/runtime-benchmarks",