feat(v1.1.9): invoke:: Rhai SDK module — sync re-entry + invoke_async

executor-core/sdk/invoke.rs adds `invoke()` and `invoke_async()` as
top-level Rhai helpers (no `::` namespace, mirroring the brief):

  invoke(target, args)        -> Dynamic  (sync, returns callee's value)
  invoke_async(target, args)  -> String   (fire-and-forget; returns execution_id)

Sync re-entry pattern:
  - bridge captures Arc<Engine> via Engine::self_arc()
  - calls engine.execute(&source, req) directly — same engine instance,
    same Services, same Limits; only SdkCallCx changes per call
  - runs inside the caller's spawn_blocking thread (no nested
    spawn_blocking, no gate re-admission — the outer execution already
    holds a permit)

Back-reference plumbing:
  - Engine gains self_weak: OnceLock<Weak<Engine>> + set_self_weak() +
    self_arc() accessor
  - picloud binary calls engine.set_self_weak(Arc::downgrade(&engine))
    right after construction
  - register_all extended with limits + Option<Arc<Engine>> params
  - Engine::execute_ast threads both through

Limits.trigger_depth_max added — mirrors TriggerConfig::max_trigger_depth.
Default 8; the picloud binary syncs from TriggerConfig::from_env() so
PICLOUD_MAX_TRIGGER_DEPTH governs both the dispatcher's fan-out cap and
the invoke depth bound.

Target parsing (string-first):
  - "/api/foo"             → InvokeTarget::Path
  - 36-char UUID-like      → InvokeTarget::Id  (uuid::Uuid parse-validated)
  - everything else        → InvokeTarget::Name

Cross-app + depth + FnPtr guards:
  - resolve() returns InvokeError::CrossApp if resolved.app_id != cx.app_id
  - bridge throws "invoke: depth limit exceeded (max N)" when
    cx.trigger_depth + 1 > limits.trigger_depth_max (checked BEFORE
    resolve to avoid a wasted DB round-trip)
  - args_to_json rejects FnPtr at any depth — closures don't survive
    invoke boundaries

invoke_async path:
  - calls services.invoke.enqueue_async() which writes an
    OutboxSourceKind::Invoke row (commit 10 wires the dispatcher arm)
  - returns the new ExecutionId as a string for caller tracking

Integration tests (sdk_invoke.rs, 6 binaries):
  - sync invoke returns callee's value (script returns body.x + 1)
  - cross-app invoke rejected (target in other app)
  - depth limit exceeded (recursive script that calls itself; throws
    before stack overflow)
  - callee receives incremented depth in cx (smoke — strict assertion
    needs ctx.trigger_depth surface, deferred to v1.2)
  - args_to_json rejects FnPtr in payload
  - invoke_async returns valid UUID string + queues args payload

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

crates/executor-core/tests/sdk_invoke.rs

@@ -0,0 +1,248 @@
+//! `invoke()` SDK bridge integration tests — runs a real Rhai engine
+//! against an in-memory `InvokeService` that fakes script resolution.
+//! Verifies sync re-entry via `Engine::set_self_weak`, the cx-threading
+//! that gives the callee `trigger_depth + 1`, cross-app rejection, depth
+//! limit, FnPtr-in-args rejection, and `invoke_async` payload shape.
+
+use std::collections::BTreeMap;
+use std::sync::{Arc, Mutex};
+
+use async_trait::async_trait;
+use chrono::Utc;
+use picloud_executor_core::{Engine, ExecRequest, InvocationType, Limits};
+use picloud_shared::{
+    AppId, ExecutionId, InvokeError, InvokeService, InvokeTarget, NoopDeadLetterService,
+    NoopDocsService, NoopEmailService, NoopEventEmitter, NoopFilesService, NoopHttpService,
+    NoopKvService, NoopModuleSource, NoopPubsubService, NoopQueueService, NoopSecretsService,
+    NoopUsersService, RequestId, ResolvedScript, ScriptId, ScriptSandbox, SdkCallCx, Services,
+};
+use serde_json::{json, Value};
+
+#[derive(Default)]
+struct FakeInvokeService {
+    scripts: Mutex<Vec<(ScriptId, AppId, String, String)>>, // (id, app, name, source)
+    async_payloads: Mutex<Vec<Value>>,
+}
+
+impl FakeInvokeService {
+    fn register(&self, app: AppId, name: &str, source: &str) -> ScriptId {
+        let id = ScriptId::new();
+        self.scripts
+            .lock()
+            .unwrap()
+            .push((id, app, name.to_string(), source.to_string()));
+        id
+    }
+}
+
+#[async_trait]
+impl InvokeService for FakeInvokeService {
+    async fn resolve(
+        &self,
+        cx: &SdkCallCx,
+        target: InvokeTarget,
+    ) -> Result<ResolvedScript, InvokeError> {
+        let entries = self.scripts.lock().unwrap().clone();
+        let hit = entries.iter().find(|(id, _app, name, _)| match &target {
+            InvokeTarget::Id(t) => t == id,
+            InvokeTarget::Name(t) => t == name,
+            InvokeTarget::Path(t) => t == name, // tests stash route paths as names
+        });
+        let (id, app, name, source): (ScriptId, AppId, String, String) = hit
+            .ok_or_else(|| InvokeError::NotFound(target.describe()))?
+            .clone();
+        if app != cx.app_id {
+            return Err(InvokeError::CrossApp);
+        }
+        Ok(ResolvedScript {
+            script_id: id,
+            app_id: app,
+            source,
+            updated_at: Utc::now(),
+            name,
+        })
+    }
+
+    async fn enqueue_async(
+        &self,
+        _cx: &SdkCallCx,
+        _target: InvokeTarget,
+        args: Value,
+    ) -> Result<ExecutionId, InvokeError> {
+        self.async_payloads.lock().unwrap().push(args);
+        Ok(ExecutionId::new())
+    }
+}
+
+fn build_engine(svc: Arc<FakeInvokeService>) -> Arc<Engine> {
+    let services = Services::new(
+        Arc::new(NoopKvService),
+        Arc::new(NoopDocsService),
+        Arc::new(NoopDeadLetterService),
+        Arc::new(NoopEventEmitter),
+        Arc::new(NoopModuleSource),
+        Arc::new(NoopHttpService),
+        Arc::new(NoopFilesService),
+        Arc::new(NoopPubsubService),
+        Arc::new(NoopSecretsService),
+        Arc::new(NoopEmailService),
+        Arc::new(NoopUsersService),
+        Arc::new(NoopQueueService),
+        svc,
+    );
+    let engine = Arc::new(Engine::new(Limits::default(), services));
+    engine.set_self_weak(Arc::downgrade(&engine));
+    engine
+}
+
+fn baseline_request(app_id: AppId) -> ExecRequest {
+    let execution_id = ExecutionId::new();
+    ExecRequest {
+        execution_id,
+        request_id: RequestId::new(),
+        script_id: ScriptId::new(),
+        script_name: "caller".into(),
+        invocation_type: InvocationType::Http,
+        path: "/caller".into(),
+        headers: BTreeMap::new(),
+        body: Value::Null,
+        params: BTreeMap::new(),
+        query: BTreeMap::new(),
+        rest: String::new(),
+        sandbox_overrides: ScriptSandbox::default(),
+        app_id,
+        principal: None,
+        trigger_depth: 0,
+        root_execution_id: execution_id,
+        is_dead_letter_handler: false,
+        event: None,
+    }
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn invoke_returns_callee_value() {
+    let app = AppId::new();
+    let svc = Arc::new(FakeInvokeService::default());
+    svc.register(app, "worker", "ctx.request.body.x + 1");
+    let engine = build_engine(svc);
+    let src = r#"
+        let n = invoke("worker", #{ x: 41 });
+        #{ statusCode: 200, body: n }
+    "#
+    .to_string();
+    let req = baseline_request(app);
+    let resp = tokio::task::spawn_blocking(move || engine.execute(&src, req))
+        .await
+        .unwrap()
+        .unwrap();
+    assert_eq!(resp.body, json!(42));
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn invoke_cross_app_rejects() {
+    let caller_app = AppId::new();
+    let other_app = AppId::new();
+    let svc = Arc::new(FakeInvokeService::default());
+    svc.register(other_app, "worker", "0"); // belongs to other_app
+    let engine = build_engine(svc);
+    let src = r#"invoke("worker", #{});"#.to_string();
+    let req = baseline_request(caller_app);
+    let res = tokio::task::spawn_blocking(move || engine.execute(&src, req))
+        .await
+        .unwrap();
+    let err = res.unwrap_err().to_string();
+    assert!(
+        err.contains("different app") || err.contains("CrossApp"),
+        "expected cross-app rejection, got: {err}"
+    );
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn invoke_depth_limit_exceeded() {
+    let app = AppId::new();
+    let svc = Arc::new(FakeInvokeService::default());
+    // recursive: calls itself again — would loop without the bound.
+    svc.register(app, "loop", r#"invoke("loop", #{})"#);
+    let engine = build_engine(svc);
+    let src = r#"invoke("loop", #{});"#.to_string();
+    let req = baseline_request(app);
+    let res = tokio::task::spawn_blocking(move || engine.execute(&src, req))
+        .await
+        .unwrap();
+    let err = res.unwrap_err().to_string();
+    assert!(
+        err.contains("depth limit"),
+        "expected depth limit error, got: {err}"
+    );
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn invoke_callee_sees_incremented_depth() {
+    let app = AppId::new();
+    let svc = Arc::new(FakeInvokeService::default());
+    // The callee returns its own trigger_depth so the caller can assert
+    // it bumped from 0 → 1.
+    svc.register(app, "depth_probe", "ctx.trigger_depth");
+    let engine = build_engine(svc);
+    let src = r#"
+        let d = invoke("depth_probe", #{});
+        #{ statusCode: 200, body: d }
+    "#
+    .to_string();
+    let req = baseline_request(app);
+    let resp = tokio::task::spawn_blocking(move || engine.execute(&src, req))
+        .await
+        .unwrap()
+        .unwrap();
+    // ctx exposes trigger_depth? — not yet (it's not in build_ctx_map).
+    // Skip the strict assertion — the test still ensures the invoke
+    // chain didn't throw. (See HANDBACK §11 for cx.trigger_depth surface
+    // exposure as a v1.2 follow-up.)
+    let _ = resp;
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn invoke_rejects_fnptr_in_args() {
+    let app = AppId::new();
+    let svc = Arc::new(FakeInvokeService::default());
+    svc.register(app, "worker", "0");
+    let engine = build_engine(svc);
+    let src = r#"
+        let f = |x| x + 1;
+        invoke("worker", #{ cb: f });
+    "#
+    .to_string();
+    let req = baseline_request(app);
+    let res = tokio::task::spawn_blocking(move || engine.execute(&src, req))
+        .await
+        .unwrap();
+    let err = res.unwrap_err().to_string();
+    assert!(
+        err.contains("FnPtr") || err.contains("closure"),
+        "expected FnPtr rejection, got: {err}"
+    );
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn invoke_async_returns_execution_id_string() {
+    let app = AppId::new();
+    let svc = Arc::new(FakeInvokeService::default());
+    svc.register(app, "worker", "0");
+    let engine = build_engine(svc.clone());
+    let src = r#"
+        let id = invoke_async("worker", #{ x: 1 });
+        #{ statusCode: 200, body: id }
+    "#
+    .to_string();
+    let req = baseline_request(app);
+    let resp = tokio::task::spawn_blocking(move || engine.execute(&src, req))
+        .await
+        .unwrap()
+        .unwrap();
+    // Body is a string — a UUID — surfaced as Json::String.
+    let id = resp.body.as_str().expect("body should be a string");
+    assert!(uuid::Uuid::parse_str(id).is_ok(), "expected UUID, got: {id}");
+    let payloads = svc.async_payloads.lock().unwrap().clone();
+    assert_eq!(payloads.len(), 1);
+    assert_eq!(payloads[0], json!({ "x": 1 }));
+}