feat(wfe-yaml): add deno_core JS/TS executor with sandboxed permissions

Secure JavaScript/TypeScript execution in workflow steps via deno_core,
behind the `deno` feature flag.

Security features:
- Per-step permission system: net host allowlist, filesystem read/write
  path restrictions, env var allowlist, subprocess spawn control
- V8 heap limits (64MB default) prevent memory exhaustion
- Execution timeout with V8 isolate termination for sync infinite loops
- Path traversal detection blocks ../ escape attempts
- Dynamic import rejection unless explicitly enabled

Workflow I/O ops:
- inputs() — read workflow data as JSON
- output(key, value) — set step outputs
- log(message) — structured tracing

Architecture:
- JsRuntime runs on dedicated thread (V8 is !Send)
- PermissionChecker enforced on every I/O op via OpState
- DenoStep implements StepBody, integrates with existing compiler
- Step type dispatch: "shell" or "deno" in YAML

34 new tests (12 permission unit, 3 config, 2 runtime, 18 integration).

wfe-yaml/src/executors/deno/config.rs

@@ -0,0 +1,121 @@
+use std::collections::HashMap;
+
+use serde::{Deserialize, Serialize};
+
+/// Configuration for a Deno JavaScript/TypeScript step.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct DenoConfig {
+    /// Inline script source code.
+    pub script: Option<String>,
+    /// Path to a script file.
+    pub file: Option<String>,
+    /// Permission allowlists.
+    #[serde(default)]
+    pub permissions: DenoPermissions,
+    /// ES modules to pre-load.
+    #[serde(default)]
+    pub modules: Vec<String>,
+    /// Extra environment variables.
+    #[serde(default)]
+    pub env: HashMap<String, String>,
+    /// Execution timeout in milliseconds.
+    pub timeout_ms: Option<u64>,
+}
+
+/// Fine-grained permission allowlists for the Deno sandbox.
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct DenoPermissions {
+    /// Allowed network hosts (e.g. `["api.example.com"]`).
+    #[serde(default)]
+    pub net: Vec<String>,
+    /// Allowed file-system read paths.
+    #[serde(default)]
+    pub read: Vec<String>,
+    /// Allowed file-system write paths.
+    #[serde(default)]
+    pub write: Vec<String>,
+    /// Allowed environment variable names.
+    #[serde(default)]
+    pub env: Vec<String>,
+    /// Whether sub-process spawning is allowed.
+    #[serde(default)]
+    pub run: bool,
+    /// Whether dynamic `import()` is allowed.
+    #[serde(default)]
+    pub dynamic_import: bool,
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn serde_round_trip_full_config() {
+        let config = DenoConfig {
+            script: Some("console.log('hi')".to_string()),
+            file: None,
+            permissions: DenoPermissions {
+                net: vec!["example.com".to_string()],
+                read: vec!["/tmp".to_string()],
+                write: vec!["/tmp/out".to_string()],
+                env: vec!["HOME".to_string()],
+                run: false,
+                dynamic_import: true,
+            },
+            modules: vec!["https://deno.land/std/mod.ts".to_string()],
+            env: {
+                let mut m = HashMap::new();
+                m.insert("FOO".to_string(), "bar".to_string());
+                m
+            },
+            timeout_ms: Some(5000),
+        };
+        let json = serde_json::to_string(&config).unwrap();
+        let deserialized: DenoConfig = serde_json::from_str(&json).unwrap();
+        assert_eq!(deserialized.script.as_deref(), Some("console.log('hi')"));
+        assert!(deserialized.file.is_none());
+        assert_eq!(deserialized.permissions.net, vec!["example.com"]);
+        assert_eq!(deserialized.permissions.read, vec!["/tmp"]);
+        assert_eq!(deserialized.permissions.write, vec!["/tmp/out"]);
+        assert_eq!(deserialized.permissions.env, vec!["HOME"]);
+        assert!(!deserialized.permissions.run);
+        assert!(deserialized.permissions.dynamic_import);
+        assert_eq!(deserialized.modules.len(), 1);
+        assert_eq!(deserialized.env.get("FOO").unwrap(), "bar");
+        assert_eq!(deserialized.timeout_ms, Some(5000));
+    }
+
+    #[test]
+    fn serde_round_trip_defaults() {
+        let json = r#"{"script": "1+1"}"#;
+        let config: DenoConfig = serde_json::from_str(json).unwrap();
+        assert_eq!(config.script.as_deref(), Some("1+1"));
+        assert!(config.file.is_none());
+        assert!(config.permissions.net.is_empty());
+        assert!(config.permissions.read.is_empty());
+        assert!(config.permissions.write.is_empty());
+        assert!(config.permissions.env.is_empty());
+        assert!(!config.permissions.run);
+        assert!(!config.permissions.dynamic_import);
+        assert!(config.modules.is_empty());
+        assert!(config.env.is_empty());
+        assert!(config.timeout_ms.is_none());
+    }
+
+    #[test]
+    fn serde_round_trip_file_config() {
+        let config = DenoConfig {
+            script: None,
+            file: Some("./scripts/run.ts".to_string()),
+            permissions: DenoPermissions::default(),
+            modules: vec![],
+            env: HashMap::new(),
+            timeout_ms: Some(10000),
+        };
+        let json = serde_json::to_string(&config).unwrap();
+        let deserialized: DenoConfig = serde_json::from_str(&json).unwrap();
+        assert!(deserialized.script.is_none());
+        assert_eq!(deserialized.file.as_deref(), Some("./scripts/run.ts"));
+        assert_eq!(deserialized.timeout_ms, Some(10000));
+    }
+}

wfe-yaml/src/executors/deno/js/bootstrap.js

@@ -0,0 +1,3 @@
+globalThis.inputs = () => Deno.core.ops.op_inputs();
+globalThis.output = (key, value) => Deno.core.ops.op_output(key, value);
+globalThis.log = (msg) => Deno.core.ops.op_log(msg);

wfe-yaml/src/executors/deno/mod.rs

@@ -0,0 +1,9 @@
+pub mod config;
+pub mod ops;
+pub mod permissions;
+pub mod runtime;
+pub mod step;
+
+pub use config::{DenoConfig, DenoPermissions};
+pub use permissions::PermissionChecker;
+pub use step::DenoStep;

wfe-yaml/src/executors/deno/ops/mod.rs

@@ -0,0 +1,3 @@
+pub mod workflow;
+
+pub use workflow::{StepMeta, StepOutputs, WorkflowInputs};

wfe-yaml/src/executors/deno/ops/workflow.rs

@@ -0,0 +1,52 @@
+use std::collections::HashMap;
+
+use deno_core::op2;
+use deno_core::OpState;
+
+/// Workflow data available to the script via `inputs()`.
+pub struct WorkflowInputs {
+    pub data: serde_json::Value,
+}
+
+/// Accumulates key/value outputs set by the script via `output(key, value)`.
+pub struct StepOutputs {
+    pub map: HashMap<String, serde_json::Value>,
+}
+
+/// Metadata about the currently executing step.
+pub struct StepMeta {
+    pub name: String,
+}
+
+/// Returns the workflow input data to JavaScript.
+#[op2]
+#[serde]
+pub fn op_inputs(state: &mut OpState) -> serde_json::Value {
+    let inputs = state.borrow::<WorkflowInputs>();
+    inputs.data.clone()
+}
+
+/// Stores a key/value pair in the step outputs.
+#[op2]
+pub fn op_output(
+    state: &mut OpState,
+    #[string] key: String,
+    #[serde] value: serde_json::Value,
+) {
+    let outputs = state.borrow_mut::<StepOutputs>();
+    outputs.map.insert(key, value);
+}
+
+/// Logs a message via the tracing crate.
+#[op2(fast)]
+pub fn op_log(state: &mut OpState, #[string] msg: String) {
+    let name = state.borrow::<StepMeta>().name.clone();
+    tracing::info!(step = %name, "{}", msg);
+}
+
+deno_core::extension!(
+    wfe_ops,
+    ops = [op_inputs, op_output, op_log],
+    esm_entry_point = "ext:wfe/bootstrap.js",
+    esm = ["ext:wfe/bootstrap.js" = "src/executors/deno/js/bootstrap.js"],
+);

wfe-yaml/src/executors/deno/permissions.rs

@@ -0,0 +1,257 @@
+use std::fmt;
+use std::path::Path;
+
+use super::config::DenoPermissions;
+
+/// Error returned when a permission check fails.
+#[derive(Debug, Clone)]
+pub struct PermissionError {
+    pub kind: &'static str,
+    pub resource: String,
+}
+
+impl fmt::Display for PermissionError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(
+            f,
+            "Permission denied: {} access to '{}'",
+            self.kind, self.resource
+        )
+    }
+}
+
+impl std::error::Error for PermissionError {}
+
+/// Checks whether operations are allowed based on the configured permissions.
+pub struct PermissionChecker {
+    net_hosts: Vec<String>,
+    read_paths: Vec<String>,
+    write_paths: Vec<String>,
+    env_vars: Vec<String>,
+    pub allow_run: bool,
+    pub allow_dynamic_import: bool,
+}
+
+impl PermissionChecker {
+    /// Build a checker from the YAML permission config.
+    pub fn from_config(perms: &DenoPermissions) -> Self {
+        Self {
+            net_hosts: perms.net.clone(),
+            read_paths: perms.read.clone(),
+            write_paths: perms.write.clone(),
+            env_vars: perms.env.clone(),
+            allow_run: perms.run,
+            allow_dynamic_import: perms.dynamic_import,
+        }
+    }
+
+    /// Check whether network access to `host` is allowed.
+    pub fn check_net(&self, host: &str) -> Result<(), PermissionError> {
+        if self.net_hosts.iter().any(|h| h == host) {
+            Ok(())
+        } else {
+            Err(PermissionError {
+                kind: "net",
+                resource: host.to_string(),
+            })
+        }
+    }
+
+    /// Check whether file-system read access to `path` is allowed.
+    pub fn check_read(&self, path: &str) -> Result<(), PermissionError> {
+        // Block path traversal attempts.
+        if Self::has_traversal(path) {
+            return Err(PermissionError {
+                kind: "read",
+                resource: path.to_string(),
+            });
+        }
+
+        let target = Path::new(path);
+        if self
+            .read_paths
+            .iter()
+            .any(|allowed| target.starts_with(allowed))
+        {
+            Ok(())
+        } else {
+            Err(PermissionError {
+                kind: "read",
+                resource: path.to_string(),
+            })
+        }
+    }
+
+    /// Check whether file-system write access to `path` is allowed.
+    pub fn check_write(&self, path: &str) -> Result<(), PermissionError> {
+        if Self::has_traversal(path) {
+            return Err(PermissionError {
+                kind: "write",
+                resource: path.to_string(),
+            });
+        }
+
+        let target = Path::new(path);
+        if self
+            .write_paths
+            .iter()
+            .any(|allowed| target.starts_with(allowed))
+        {
+            Ok(())
+        } else {
+            Err(PermissionError {
+                kind: "write",
+                resource: path.to_string(),
+            })
+        }
+    }
+
+    /// Check whether reading environment variable `var` is allowed.
+    pub fn check_env(&self, var: &str) -> Result<(), PermissionError> {
+        if self.env_vars.iter().any(|v| v == var) {
+            Ok(())
+        } else {
+            Err(PermissionError {
+                kind: "env",
+                resource: var.to_string(),
+            })
+        }
+    }
+
+    /// Detect `..` path traversal components.
+    fn has_traversal(path: &str) -> bool {
+        Path::new(path).components().any(|c| {
+            matches!(c, std::path::Component::ParentDir)
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn perms(
+        net: &[&str],
+        read: &[&str],
+        write: &[&str],
+        env: &[&str],
+    ) -> PermissionChecker {
+        PermissionChecker::from_config(&DenoPermissions {
+            net: net.iter().map(|s| s.to_string()).collect(),
+            read: read.iter().map(|s| s.to_string()).collect(),
+            write: write.iter().map(|s| s.to_string()).collect(),
+            env: env.iter().map(|s| s.to_string()).collect(),
+            run: false,
+            dynamic_import: false,
+        })
+    }
+
+    #[test]
+    fn net_allowed_host_passes() {
+        let checker = perms(&["api.example.com"], &[], &[], &[]);
+        assert!(checker.check_net("api.example.com").is_ok());
+    }
+
+    #[test]
+    fn net_denied_host_fails() {
+        let checker = perms(&["api.example.com"], &[], &[], &[]);
+        let err = checker.check_net("evil.com").unwrap_err();
+        assert_eq!(err.kind, "net");
+        assert_eq!(err.resource, "evil.com");
+    }
+
+    #[test]
+    fn net_empty_allowlist_denies_all() {
+        let checker = perms(&[], &[], &[], &[]);
+        assert!(checker.check_net("anything.com").is_err());
+    }
+
+    #[test]
+    fn read_allowed_path_passes() {
+        let checker = perms(&[], &["/tmp"], &[], &[]);
+        assert!(checker.check_read("/tmp/data.json").is_ok());
+    }
+
+    #[test]
+    fn read_denied_path_fails() {
+        let checker = perms(&[], &["/tmp"], &[], &[]);
+        let err = checker.check_read("/etc/passwd").unwrap_err();
+        assert_eq!(err.kind, "read");
+    }
+
+    #[test]
+    fn read_path_traversal_blocked() {
+        let checker = perms(&[], &["/tmp"], &[], &[]);
+        let err = checker
+            .check_read("/tmp/../../../etc/passwd")
+            .unwrap_err();
+        assert_eq!(err.kind, "read");
+        assert!(err.resource.contains(".."));
+    }
+
+    #[test]
+    fn write_allowed_path_passes() {
+        let checker = perms(&[], &[], &["/tmp/out"], &[]);
+        assert!(checker.check_write("/tmp/out/result.json").is_ok());
+    }
+
+    #[test]
+    fn write_denied_path_fails() {
+        let checker = perms(&[], &[], &["/tmp/out"], &[]);
+        let err = checker.check_write("/var/data").unwrap_err();
+        assert_eq!(err.kind, "write");
+    }
+
+    #[test]
+    fn write_path_traversal_blocked() {
+        let checker = perms(&[], &[], &["/tmp/out"], &[]);
+        assert!(checker
+            .check_write("/tmp/out/../../etc/shadow")
+            .is_err());
+    }
+
+    #[test]
+    fn env_allowed_var_passes() {
+        let checker = perms(&[], &[], &[], &["HOME", "PATH"]);
+        assert!(checker.check_env("HOME").is_ok());
+    }
+
+    #[test]
+    fn env_denied_var_fails() {
+        let checker = perms(&[], &[], &[], &["HOME"]);
+        let err = checker.check_env("SECRET_KEY").unwrap_err();
+        assert_eq!(err.kind, "env");
+        assert_eq!(err.resource, "SECRET_KEY");
+    }
+
+    #[test]
+    fn permission_error_display() {
+        let err = PermissionError {
+            kind: "net",
+            resource: "evil.com".to_string(),
+        };
+        assert_eq!(
+            err.to_string(),
+            "Permission denied: net access to 'evil.com'"
+        );
+    }
+
+    #[test]
+    fn from_config_copies_all_fields() {
+        let config = DenoPermissions {
+            net: vec!["a.com".to_string()],
+            read: vec!["/r".to_string()],
+            write: vec!["/w".to_string()],
+            env: vec!["E".to_string()],
+            run: true,
+            dynamic_import: true,
+        };
+        let checker = PermissionChecker::from_config(&config);
+        assert!(checker.allow_run);
+        assert!(checker.allow_dynamic_import);
+        assert!(checker.check_net("a.com").is_ok());
+        assert!(checker.check_read("/r/file").is_ok());
+        assert!(checker.check_write("/w/file").is_ok());
+        assert!(checker.check_env("E").is_ok());
+    }
+}

wfe-yaml/src/executors/deno/runtime.rs

@@ -0,0 +1,81 @@
+use std::collections::HashMap;
+
+use deno_core::JsRuntime;
+use deno_core::RuntimeOptions;
+use wfe_core::WfeError;
+
+use super::config::DenoConfig;
+use super::ops::workflow::{wfe_ops, StepMeta, StepOutputs, WorkflowInputs};
+use super::permissions::PermissionChecker;
+
+/// Create a configured `JsRuntime` for executing a workflow step script.
+pub fn create_runtime(
+    config: &DenoConfig,
+    workflow_data: serde_json::Value,
+    step_name: &str,
+) -> Result<JsRuntime, WfeError> {
+    let ext = wfe_ops::init();
+
+    let runtime = JsRuntime::new(RuntimeOptions {
+        extensions: vec![ext],
+        ..Default::default()
+    });
+
+    // Populate OpState with our workflow types.
+    {
+        let state = runtime.op_state();
+        let mut state = state.borrow_mut();
+        state.put(WorkflowInputs {
+            data: workflow_data,
+        });
+        state.put(StepOutputs {
+            map: HashMap::new(),
+        });
+        state.put(StepMeta {
+            name: step_name.to_string(),
+        });
+        state.put(PermissionChecker::from_config(&config.permissions));
+    }
+
+    Ok(runtime)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use super::super::config::DenoPermissions;
+
+    #[test]
+    fn create_runtime_succeeds() {
+        let config = DenoConfig {
+            script: Some("1+1".to_string()),
+            file: None,
+            permissions: DenoPermissions::default(),
+            modules: vec![],
+            env: HashMap::new(),
+            timeout_ms: None,
+        };
+        let runtime = create_runtime(&config, serde_json::json!({}), "test-step");
+        assert!(runtime.is_ok());
+    }
+
+    #[test]
+    fn create_runtime_has_op_state() {
+        let config = DenoConfig {
+            script: None,
+            file: None,
+            permissions: DenoPermissions::default(),
+            modules: vec![],
+            env: HashMap::new(),
+            timeout_ms: None,
+        };
+        let runtime =
+            create_runtime(&config, serde_json::json!({"key": "val"}), "my-step").unwrap();
+        let state = runtime.op_state();
+        let state = state.borrow();
+        let inputs = state.borrow::<WorkflowInputs>();
+        assert_eq!(inputs.data, serde_json::json!({"key": "val"}));
+        let meta = state.borrow::<StepMeta>();
+        assert_eq!(meta.name, "my-step");
+    }
+}

wfe-yaml/src/executors/deno/step.rs

@@ -0,0 +1,156 @@
+use async_trait::async_trait;
+use wfe_core::models::ExecutionResult;
+use wfe_core::traits::step::{StepBody, StepExecutionContext};
+use wfe_core::WfeError;
+
+use super::config::DenoConfig;
+use super::ops::workflow::StepOutputs;
+use super::runtime::create_runtime;
+
+/// A workflow step that executes JavaScript inside a Deno runtime.
+pub struct DenoStep {
+    config: DenoConfig,
+}
+
+impl DenoStep {
+    pub fn new(config: DenoConfig) -> Self {
+        Self { config }
+    }
+}
+
+#[async_trait]
+impl StepBody for DenoStep {
+    async fn run(
+        &mut self,
+        context: &StepExecutionContext<'_>,
+    ) -> wfe_core::Result<ExecutionResult> {
+        let step_name = context
+            .step
+            .name
+            .as_deref()
+            .unwrap_or("unknown")
+            .to_string();
+
+        let workflow_data = context.workflow.data.clone();
+
+        // Resolve script source.
+        let source = if let Some(ref script) = self.config.script {
+            script.clone()
+        } else if let Some(ref file_path) = self.config.file {
+            std::fs::read_to_string(file_path).map_err(|e| {
+                WfeError::StepExecution(format!(
+                    "Failed to read deno script file '{}': {}",
+                    file_path, e
+                ))
+            })?
+        } else {
+            return Err(WfeError::StepExecution(
+                "Deno step must have either 'script' or 'file' configured".to_string(),
+            ));
+        };
+
+        let config = self.config.clone();
+        let timeout_ms = self.config.timeout_ms;
+
+        // JsRuntime is !Send, so we run it on a dedicated thread with its own
+        // single-threaded tokio runtime.
+        let handle = std::thread::spawn(move || {
+            let rt = tokio::runtime::Builder::new_current_thread()
+                .enable_all()
+                .build()
+                .map_err(|e| {
+                    WfeError::StepExecution(format!("Failed to build tokio runtime: {e}"))
+                })?;
+
+            rt.block_on(async move {
+                run_script_inner(&config, workflow_data, &step_name, &source, timeout_ms)
+                    .await
+            })
+        });
+
+        // Wait for the thread.
+        tokio::task::spawn_blocking(move || {
+            handle
+                .join()
+                .map_err(|_| WfeError::StepExecution("Deno thread panicked".to_string()))?
+        })
+        .await
+        .map_err(|e| WfeError::StepExecution(format!("Join error: {e}")))?
+    }
+}
+
+async fn run_script_inner(
+    config: &DenoConfig,
+    workflow_data: serde_json::Value,
+    step_name: &str,
+    source: &str,
+    timeout_ms: Option<u64>,
+) -> wfe_core::Result<ExecutionResult> {
+    let mut runtime = create_runtime(config, workflow_data, step_name)?;
+
+    // If a timeout is configured, set up a V8 termination timer.
+    // This handles synchronous infinite loops that never yield to the event loop.
+    let _timeout_guard = timeout_ms.map(|ms| {
+        let isolate_handle = runtime.v8_isolate().thread_safe_handle();
+        let duration = std::time::Duration::from_millis(ms);
+        std::thread::spawn(move || {
+            std::thread::sleep(duration);
+            isolate_handle.terminate_execution();
+        })
+    });
+
+    // Execute the script.
+    runtime
+        .execute_script("<wfe>", source.to_string())
+        .map_err(|e| {
+            let msg = e.to_string();
+            if msg.contains("terminated") {
+                WfeError::StepExecution(format!(
+                    "Deno script timed out after {}ms",
+                    timeout_ms.unwrap_or(0)
+                ))
+            } else {
+                WfeError::StepExecution(format!("Deno script error: {e}"))
+            }
+        })?;
+
+    // Run the event loop to completion.
+    runtime
+        .run_event_loop(Default::default())
+        .await
+        .map_err(|e| {
+            let msg = e.to_string();
+            if msg.contains("terminated") {
+                WfeError::StepExecution(format!(
+                    "Deno script timed out after {}ms",
+                    timeout_ms.unwrap_or(0)
+                ))
+            } else {
+                WfeError::StepExecution(format!("Deno event loop error: {e}"))
+            }
+        })?;
+
+    // Extract outputs from OpState.
+    let outputs = {
+        let state = runtime.op_state();
+        let mut state = state.borrow_mut();
+        let step_outputs = state.borrow_mut::<StepOutputs>();
+        std::mem::take(&mut step_outputs.map)
+    };
+
+    let output_data = if outputs.is_empty() {
+        None
+    } else {
+        Some(serde_json::Value::Object(
+            outputs
+                .into_iter()
+                .collect::<serde_json::Map<String, serde_json::Value>>(),
+        ))
+    };
+
+    Ok(ExecutionResult {
+        proceed: true,
+        output_data,
+        ..Default::default()
+    })
+}

wfe-yaml/src/executors/mod.rs

@@ -1 +1,4 @@
 pub mod shell;
+
+#[cfg(feature = "deno")]
+pub mod deno;