refactor(executor-core): extract sdk/ module + move json↔dynamic bridge

Hoist the json_to_dynamic / dynamic_to_json helpers out of engine.rs
into a new sdk/bridge.rs so the v1.1.x service modules (KV, docs, …)
can use them without engine.rs being the sole owner. No behavioural
change — the sdk_contract round-trip test pins the observable JSON
fidelity.

Also lands the structural shape that subsequent v1.1.x PRs hook into:

  - sdk::register_all(engine, services, cx) — single per-call hook
    every stateful service registers through. Body is a no-op for
    v1.1.0; SdkCallCx construction inside Engine::execute lands in
    the next commit alongside the new ExecRequest fields it reads.
  - sdk::cx re-exports picloud_shared::SdkCallCx so SDK callers don't
    cross-import shared for one type.

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

crates/executor-core/src/engine.rs

@@ -8,6 +8,7 @@ use rhai::{Dynamic, Engine as RhaiEngine, EvalAltResult, Map, Module, Scope};
 use serde_json::Value as Json;
 
 use crate::sandbox::Limits;
+use crate::sdk::bridge::{dynamic_to_json, json_to_dynamic};
 use crate::types::{
     ExecError, ExecRequest, ExecResponse, ExecStats, InvocationType, LogEntry, LogLevel,
 };
@@ -265,69 +266,6 @@ fn parse_structured_response(map: Map) -> Result<(u16, BTreeMap<String, String>,
     Ok((status_code, headers, body))
 }
 
-// ----------------------------------------------------------------------------
-// Rhai ↔ serde_json bridges
-// ----------------------------------------------------------------------------
-
-fn json_to_dynamic(value: Json) -> Dynamic {
-    match value {
-        Json::Null => Dynamic::UNIT,
-        Json::Bool(b) => b.into(),
-        Json::Number(n) => {
-            if let Some(i) = n.as_i64() {
-                i.into()
-            } else if let Some(f) = n.as_f64() {
-                f.into()
-            } else {
-                n.to_string().into()
-            }
-        }
-        Json::String(s) => s.into(),
-        Json::Array(arr) => arr
-            .into_iter()
-            .map(json_to_dynamic)
-            .collect::<Vec<Dynamic>>()
-            .into(),
-        Json::Object(obj) => {
-            let mut m = Map::new();
-            for (k, v) in obj {
-                m.insert(k.into(), json_to_dynamic(v));
-            }
-            Dynamic::from(m)
-        }
-    }
-}
-
-fn dynamic_to_json(value: &Dynamic) -> Json {
-    if value.is_unit() {
-        return Json::Null;
-    }
-    if let Ok(b) = value.as_bool() {
-        return Json::Bool(b);
-    }
-    if let Ok(i) = value.as_int() {
-        return Json::Number(i.into());
-    }
-    if let Ok(f) = value.as_float() {
-        return serde_json::Number::from_f64(f).map_or(Json::Null, Json::Number);
-    }
-    if value.is_string() {
-        return Json::String(value.clone().into_string().unwrap_or_default());
-    }
-    if let Some(arr) = value.clone().try_cast::<rhai::Array>() {
-        return Json::Array(arr.iter().map(dynamic_to_json).collect());
-    }
-    if let Some(map) = value.clone().try_cast::<Map>() {
-        let mut out = serde_json::Map::new();
-        for (k, v) in map {
-            out.insert(k.to_string(), dynamic_to_json(&v));
-        }
-        return Json::Object(out);
-    }
-    // Anything else (timestamps, custom types) — best-effort string form.
-    Json::String(value.to_string())
-}
-
 // ----------------------------------------------------------------------------
 // Error mapping
 // ----------------------------------------------------------------------------

crates/executor-core/src/lib.rs

@@ -8,6 +8,7 @@ pub mod context;
 pub mod engine;
 pub mod logging;
 pub mod sandbox;
+pub mod sdk;
 pub mod types;
 
 pub use engine::Engine;

crates/executor-core/src/sdk/bridge.rs

@@ -0,0 +1,79 @@
+//! JSON ↔ Rhai `Dynamic` value bridge.
+//!
+//! Originally inline in `engine.rs`; moved here for v1.1.0 so future
+//! service modules (KV in v1.1.1, docs in v1.1.2, …) can convert
+//! values without `engine.rs` being the only owner of the conversions.
+//! Behaviour is unchanged from the pre-extraction implementation —
+//! `sdk_contract.rs::json_round_trip_preserves_nested_shapes` pins the
+//! observable round-trip.
+
+use rhai::{Dynamic, Map};
+use serde_json::Value as Json;
+
+/// Convert a `serde_json::Value` into a Rhai `Dynamic` suitable for
+/// pushing into a script's scope. Numbers prefer the narrowest type
+/// (`i64` over `f64`); anything that can't round-trip falls back to a
+/// string so the script always sees a defined value.
+#[must_use]
+pub fn json_to_dynamic(value: Json) -> Dynamic {
+    match value {
+        Json::Null => Dynamic::UNIT,
+        Json::Bool(b) => b.into(),
+        Json::Number(n) => {
+            if let Some(i) = n.as_i64() {
+                i.into()
+            } else if let Some(f) = n.as_f64() {
+                f.into()
+            } else {
+                n.to_string().into()
+            }
+        }
+        Json::String(s) => s.into(),
+        Json::Array(arr) => arr
+            .into_iter()
+            .map(json_to_dynamic)
+            .collect::<Vec<Dynamic>>()
+            .into(),
+        Json::Object(obj) => {
+            let mut m = Map::new();
+            for (k, v) in obj {
+                m.insert(k.into(), json_to_dynamic(v));
+            }
+            Dynamic::from(m)
+        }
+    }
+}
+
+/// Convert a Rhai `Dynamic` back to a `serde_json::Value`. Custom Rhai
+/// types (timestamps, user-registered modules) fall back to their
+/// `Display` form so they appear as strings in JSON output rather than
+/// failing the response build.
+#[must_use]
+pub fn dynamic_to_json(value: &Dynamic) -> Json {
+    if value.is_unit() {
+        return Json::Null;
+    }
+    if let Ok(b) = value.as_bool() {
+        return Json::Bool(b);
+    }
+    if let Ok(i) = value.as_int() {
+        return Json::Number(i.into());
+    }
+    if let Ok(f) = value.as_float() {
+        return serde_json::Number::from_f64(f).map_or(Json::Null, Json::Number);
+    }
+    if value.is_string() {
+        return Json::String(value.clone().into_string().unwrap_or_default());
+    }
+    if let Some(arr) = value.clone().try_cast::<rhai::Array>() {
+        return Json::Array(arr.iter().map(dynamic_to_json).collect());
+    }
+    if let Some(map) = value.clone().try_cast::<Map>() {
+        let mut out = serde_json::Map::new();
+        for (k, v) in map {
+            out.insert(k.to_string(), dynamic_to_json(&v));
+        }
+        return Json::Object(out);
+    }
+    Json::String(value.to_string())
+}

crates/executor-core/src/sdk/cx.rs

@@ -0,0 +1,10 @@
+//! Re-export of `picloud_shared::SdkCallCx`.
+//!
+//! The type itself lives in `picloud-shared` because future stateful
+//! service impls live in `manager-core` (which `executor-core` must
+//! not depend on) and need to reference the same cx shape. This
+//! re-export lets executor-side code write
+//! `use picloud_executor_core::sdk::SdkCallCx;` instead of reaching
+//! into `picloud_shared` for one type.
+
+pub use picloud_shared::SdkCallCx;

crates/executor-core/src/sdk/mod.rs

@@ -0,0 +1,39 @@
+//! SDK plumbing — types and the per-call registration entry point.
+//!
+//! `executor-core` is responsible for building the per-invocation Rhai
+//! engine and wiring stateful services into it. v1.1.0 ships the
+//! shapes (`Services` bundle, `SdkCallCx`, `register_all` entry point)
+//! but no actual services — subsequent v1.1.x PRs (KV in v1.1.1,
+//! docs in v1.1.2, …) extend `register_all` rather than re-threading
+//! plumbing through `engine.rs`.
+//!
+//! Bridge functions (`json_to_dynamic` / `dynamic_to_json`) also live
+//! here so service modules can convert values without `engine.rs`
+//! being the only home for the conversion logic.
+
+pub mod bridge;
+pub mod cx;
+
+pub use bridge::{dynamic_to_json, json_to_dynamic};
+pub use cx::SdkCallCx;
+
+use std::sync::Arc;
+
+use picloud_shared::Services;
+use rhai::Engine as RhaiEngine;
+
+/// Single hook every v1.1.x stateful service registers into. Called
+/// once per invocation, just after `build_engine` constructs the
+/// sandboxed Rhai engine and just before script compilation.
+///
+/// v1.1.0 ships an intentionally empty body — the call site exists so
+/// future PRs (KV first) drop their registration logic here rather
+/// than reaching into `engine.rs::build_engine`. The signature is
+/// locked: subsequent PRs MUST keep the same parameter shape so that
+/// hosts don't have to re-thread the plumbing.
+pub fn register_all(engine: &mut RhaiEngine, services: &Services, cx: Arc<SdkCallCx>) {
+    // Intentionally inert in v1.1.0. The unused-suppression below is a
+    // load-bearing placeholder: future PRs replace this `let _` with
+    // real `register_kv(engine, services, cx.clone())` calls etc.
+    let _ = (engine, services, cx);
+}