US-005: Typed task packet format with TaskScope enum

- Add TaskScope enum with Workspace, Module, SingleFile, Custom variants
- Update TaskPacket struct with scope_path and worktree fields
- Add validation for scope-specific requirements
- Fix tests in task_packet.rs, task_registry.rs, and tools/src/lib.rs
- Export TaskScope from runtime crate

Closes US-005 (Phase 4)

rust/crates/runtime/src/task_packet.rs

@@ -1,11 +1,42 @@
 use serde::{Deserialize, Serialize};
 use std::fmt::{Display, Formatter};
 
+/// Task scope resolution for defining the granularity of work.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "snake_case")]
+pub enum TaskScope {
+    /// Work across the entire workspace
+    Workspace,
+    /// Work within a specific module/crate
+    Module,
+    /// Work on a single file
+    SingleFile,
+    /// Custom scope defined by the user
+    Custom,
+}
+
+impl std::fmt::Display for TaskScope {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Workspace => write!(f, "workspace"),
+            Self::Module => write!(f, "module"),
+            Self::SingleFile => write!(f, "single-file"),
+            Self::Custom => write!(f, "custom"),
+        }
+    }
+}
+
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
 pub struct TaskPacket {
     pub objective: String,
-    pub scope: String,
+    pub scope: TaskScope,
+    /// Optional scope path when scope is `Module`, `SingleFile`, or `Custom`
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub scope_path: Option<String>,
     pub repo: String,
+    /// Worktree path for the task
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub worktree: Option<String>,
     pub branch_policy: String,
     pub acceptance_tests: Vec<String>,
     pub commit_policy: String,
@@ -57,7 +88,6 @@ pub fn validate_packet(packet: TaskPacket) -> Result<ValidatedPacket, TaskPacket
     let mut errors = Vec::new();
 
     validate_required("objective", &packet.objective, &mut errors);
-    validate_required("scope", &packet.scope, &mut errors);
     validate_required("repo", &packet.repo, &mut errors);
     validate_required("branch_policy", &packet.branch_policy, &mut errors);
     validate_required("commit_policy", &packet.commit_policy, &mut errors);
@@ -68,6 +98,9 @@ pub fn validate_packet(packet: TaskPacket) -> Result<ValidatedPacket, TaskPacket
     );
     validate_required("escalation_policy", &packet.escalation_policy, &mut errors);
 
+    // Validate scope-specific requirements
+    validate_scope_requirements(&packet, &mut errors);
+
     for (index, test) in packet.acceptance_tests.iter().enumerate() {
         if test.trim().is_empty() {
             errors.push(format!(
@@ -83,6 +116,21 @@ pub fn validate_packet(packet: TaskPacket) -> Result<ValidatedPacket, TaskPacket
     }
 }
 
+fn validate_scope_requirements(packet: &TaskPacket, errors: &mut Vec<String>) {
+    // Scope path is required for Module, SingleFile, and Custom scopes
+    let needs_scope_path = matches!(
+        packet.scope,
+        TaskScope::Module | TaskScope::SingleFile | TaskScope::Custom
+    );
+
+    if needs_scope_path && packet.scope_path.as_ref().is_none_or(|p| p.trim().is_empty()) {
+        errors.push(format!(
+            "scope_path is required for scope '{}'",
+            packet.scope
+        ));
+    }
+}
+
 fn validate_required(field: &str, value: &str, errors: &mut Vec<String>) {
     if value.trim().is_empty() {
         errors.push(format!("{field} must not be empty"));
@@ -96,8 +144,10 @@ mod tests {
     fn sample_packet() -> TaskPacket {
         TaskPacket {
             objective: "Implement typed task packet format".to_string(),
-            scope: "runtime/task system".to_string(),
+            scope: TaskScope::Module,
+            scope_path: Some("runtime/task system".to_string()),
             repo: "claw-code-parity".to_string(),
+            worktree: Some("/tmp/wt-1".to_string()),
             branch_policy: "origin/main only".to_string(),
             acceptance_tests: vec![
                 "cargo build --workspace".to_string(),
@@ -119,9 +169,12 @@ mod tests {
 
     #[test]
     fn invalid_packet_accumulates_errors() {
+        use super::TaskScope;
         let packet = TaskPacket {
             objective: " ".to_string(),
-            scope: String::new(),
+            scope: TaskScope::Workspace,
+            scope_path: None,
+            worktree: None,
             repo: String::new(),
             branch_policy: "\t".to_string(),
             acceptance_tests: vec!["ok".to_string(), " ".to_string()],
@@ -136,9 +189,6 @@ mod tests {
         assert!(error
             .errors()
             .contains(&"objective must not be empty".to_string()));
-        assert!(error
-            .errors()
-            .contains(&"scope must not be empty".to_string()));
         assert!(error
             .errors()
             .contains(&"repo must not be empty".to_string()));

rust/crates/runtime/src/task_registry.rs

@@ -85,11 +85,12 @@ impl TaskRegistry {
         packet: TaskPacket,
     ) -> Result<Task, TaskPacketValidationError> {
         let packet = validate_packet(packet)?.into_inner();
-        Ok(self.create_task(
-            packet.objective.clone(),
-            Some(packet.scope.clone()),
-            Some(packet),
-        ))
+        // Use scope_path as description if available, otherwise use scope as string
+        let description = packet
+            .scope_path
+            .clone()
+            .or_else(|| Some(packet.scope.to_string()));
+        Ok(self.create_task(packet.objective.clone(), description, Some(packet)))
     }
 
     fn create_task(
@@ -249,10 +250,13 @@ mod tests {
 
     #[test]
     fn creates_task_from_packet() {
+        use crate::task_packet::TaskScope;
         let registry = TaskRegistry::new();
         let packet = TaskPacket {
             objective: "Ship task packet support".to_string(),
-            scope: "runtime/task system".to_string(),
+            scope: TaskScope::Module,
+            scope_path: Some("runtime/task system".to_string()),
+            worktree: Some("/tmp/wt-task".to_string()),
             repo: "claw-code-parity".to_string(),
             branch_policy: "origin/main only".to_string(),
             acceptance_tests: vec!["cargo test --workspace".to_string()],

rust/crates/tools/src/lib.rs

@@ -9554,9 +9554,12 @@ printf 'pwsh:%s' "$1"
 
     #[test]
     fn run_task_packet_creates_packet_backed_task() {
+        use runtime::task_packet::TaskScope;
         let result = run_task_packet(TaskPacket {
             objective: "Ship packetized runtime task".to_string(),
-            scope: "runtime/task system".to_string(),
+            scope: TaskScope::Module,
+            scope_path: Some("runtime/task system".to_string()),
+            worktree: Some("/tmp/wt-packet".to_string()),
             repo: "claw-code-parity".to_string(),
             branch_policy: "origin/main only".to_string(),
             acceptance_tests: vec![