docs(slice-2d): findings consolidados — serde/std leak via types/std identified

Slice 2d empirical investigation completada (sesión 2 cont 2026-05-24):
- WASM_BUILD_STD=0 resuelve alloc/exchange_malloc (Slice 2c attempt #5)
- NEW layer: panic_impl duplicate via serde/std leak transitive
- Diagnostic vía cargo tree wasm32 -e features: ruta exacta identificada
  `origin-chain-types feature "std"` → `serde feature "std"` activation
- Root cause: dep transitive activa types/std en wasm32 build incluso
  con --no-default-features (probable macro expansion automation)

Slice 2e future requires architectural fix:
- [patch.crates-io] serde override con strict no-std
- O sp-io feature gate adjust
- O wait stable2512-4+ upstream

Mientras Slice 2e land: build.rs no-op + Slice 3 v0.0.13 mock-WASM estable.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

crates/origin-chain-runtime/build.rs

@@ -1,47 +1,28 @@
-//! # Build script — Slice 2c canonical multi-attempt findings registered
+//! # Build script — Slice 2d findings registered, deferred future session
 //!
-//! Slice 2b investigation registered (sesión 1, 2026-05-21) — 4 fix attempts
-//! NO solved 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
+//! Slice 2c attempts 1-4 (Slice 2b 2026-05-21): direct serde / pin / profile /
+//! build_using_defaults — ALL NO solved alloc/exchange_malloc conflict.
 //!
-//! Slice 2c attempt #5 (Charon sesión 2 cont. 2026-05-24) — empirical test
-//! WASM_BUILD_STD=0 explicit override canonical. Upstream docs confirman:
-//! "WASM_BUILD_STD is disabled by default for WASM target and Rust >= 1.84".
+//! Slice 2c attempt #5 + Slice 2d (sesión 2 cont 2026-05-24):
+//! - WASM_BUILD_STD=0 explicit override → alloc/exchange_malloc RESUELTO
+//! - NEW layer surface: panic_impl duplicate via serde/std leak transitive
+//! - Diagnostic via cargo tree --target wasm32 -e features: identified
+//!   `origin-chain-types feature "std"` → `serde feature "std"` activation path
+//! - Root cause: algún dep transitive activates types/std en wasm32 build
+//!   incluso con --no-default-features (probable: macro expansion automation)
 //!
-//! ## Attempt #5 finding canonical (BIG progress)
+//! ## Path forward Slice 2e future
 //!
-//! `WASM_BUILD_STD=0` explicit + WasmBuilder re-enabled → **alloc/exchange_malloc
-//! issue RESUELTO canonical**. Pero canonical surface NEW error canonical:
+//! Requires architectural fix:
+//! - [patch.crates-io] serde override con strict no-std
+//! - O sp-io feature gate adjust
+//! - O wait stable2512-4+ upstream fix
 //!
-//! ```
-//! error[E0152]: found duplicate lang item `panic_impl`
-//!   --> sp-io-40.0.1/src/lib.rs:1774:1
-//!   = note: the lang item is first defined in crate `std` (which `serde` depends on)
-//!   = note: first definition in `std` loaded from libstd-*.rlib
-//!   = note: second definition in the local crate (`sp_io`)
-//! ```
-//!
-//! Diagnosis canonical: serde está siendo pulled con `std` feature canonical
-//! transitively desde algún dep canonical (parity-scale-codec o frame-*) →
-//! libstd canonical linked en wasm32 → conflict canonical con sp_io::panic
-//! handler canonical (que define panic_impl para no_std runtime).
-//!
-//! ## Path canonical resolución pending (Slice 2d canonical future)
-//!
-//! Requires deeper investigation canonical:
-//! - Inverted feature tree exact culprit identification canonical
-//! - Override canonical: `[patch.crates-io] serde = { ... }` con strict no-std
-//! - O explicit `WASM_BUILD_RUSTFLAGS` canonical override
-//! - O wait stable2512-4+ upstream canonical fix
-//!
-//! Mientras Slice 2d land canonical, build script canonical mantain no-op +
-//! Slice 3 (v0.0.13) mock-WASM fallback canonical path estable canonical.
+//! Mientras Slice 2e land, build script no-op + Slice 3 (v0.0.13) mock-WASM
+//! fallback (chain_spec.rs en node crate via serde_json puro) sigue siendo
+//! path estable. Cross-pillar consumers (Trinity/Codex/Ethos/Atelier) ya
+//! pueden consumir ChainSpec JSON output sin necesidad runtime WASM real.
 
 fn main() {
-    // No-op canonical — Slice 2d canonical land WASM_BINARY post serde/std
-    // leakage canonical resolution canonical. Slice 3 mock-WASM (chain_spec
-    // builder JSON canonical) sigue siendo el path canonical estable canonical.
+    // No-op — Slice 2e future resolves WASM_BINARY. Slice 3 mock-WASM estable.
 }