fix: complete multi-workdir isolation and launch UI

crates/tools/src/edit.rs

@@ -52,7 +52,9 @@ impl Tool for EditTool {
             params.target_workdir.as_deref(),
             workdir::WorkdirSessionCapability::Edit,
         )?;
-        let tracker = self.tracker.scoped(selected.alias.as_str());
+        let tracker = self
+            .tracker
+            .scoped_attachment(&selected.alias, selected.generation);
         let path = WorkdirPath::new(&params.file_path).map_err(ToolsError::from)?;
         tracing::debug!(path = %path, replace_all = params.replace_all, "Edit");
 

crates/tools/src/read.rs

@@ -53,7 +53,9 @@ impl Tool for ReadTool {
             params.target_workdir.as_deref(),
             workdir::WorkdirSessionCapability::Read,
         )?;
-        let tracker = self.tracker.scoped(selected.alias.as_str());
+        let tracker = self
+            .tracker
+            .scoped_attachment(&selected.alias, selected.generation);
         let offset = params.offset.unwrap_or(0);
         let limit = params.limit.unwrap_or(DEFAULT_LIMIT).max(1);
 
@@ -216,7 +218,7 @@ mod tests {
         // History recorded
         assert!(
             tracker
-                .scoped("workdir")
+                .scoped_attachment(&workdir::WorkdirAttachmentAlias::new("workdir").unwrap(), 0,)
                 .expected_workdir_hash(&WorkdirPath::new("a.txt").unwrap())
                 .is_ok()
         );
@@ -247,7 +249,7 @@ mod tests {
 
     #[tokio::test]
     async fn read_tool_missing_file() {
-        let (dir, fs, tracker) = setup();
+        let (_dir, fs, tracker) = setup();
         let def = read_tool(fs, tracker);
         let (_, tool) = def();
         let input = serde_json::json!({

crates/tools/src/tracker.rs

@@ -161,8 +161,9 @@ impl Tracker {
     }
 
     /// Return a view whose read-before-mutation state is isolated to one
-    /// Worker-local attachment alias while aggregate recency/change statistics
-    /// remain shared with the Worker tracker.
+    /// attachment incarnation (the Worker-local alias plus router generation),
+    /// while aggregate recency/change statistics remain shared with the Worker
+    /// tracker.
     pub fn scoped(&self, namespace: impl Into<String>) -> Self {
         Self {
             inner: self.inner.clone(),
@@ -171,6 +172,14 @@ impl Tracker {
         }
     }
 
+    pub(crate) fn scoped_attachment(
+        &self,
+        alias: &workdir::WorkdirAttachmentAlias,
+        generation: u64,
+    ) -> Self {
+        self.scoped(format!("{}#{generation}", alias.as_str()))
+    }
+
     fn key(&self, path: PathBuf) -> TrackedPath {
         TrackedPath {
             namespace: self.namespace.clone(),

crates/tools/src/write.rs

@@ -49,7 +49,9 @@ impl Tool for WriteTool {
             params.target_workdir.as_deref(),
             workdir::WorkdirSessionCapability::Write,
         )?;
-        let tracker = self.tracker.scoped(selected.alias.as_str());
+        let tracker = self
+            .tracker
+            .scoped_attachment(&selected.alias, selected.generation);
         let path = WorkdirPath::new(&params.file_path).map_err(ToolsError::from)?;
         tracing::debug!(path = %path, bytes = params.content.len(), "Write");
 

crates/tools/tests/integration.rs

@@ -339,6 +339,66 @@ async fn routed_tools_observe_detach_after_registration() {
     router.close_all().await.unwrap();
 }
 
+#[tokio::test]
+async fn detach_and_reattach_same_alias_requires_a_fresh_read() {
+    let first = TempDir::new().unwrap();
+    let second = TempDir::new().unwrap();
+    let spill = TempDir::new().unwrap();
+    std::fs::write(first.path().join("same.txt"), "same bytes\n").unwrap();
+    std::fs::write(second.path().join("same.txt"), "same bytes\n").unwrap();
+
+    let router = Arc::new(WorkdirSessionRouter::new());
+    let alias = WorkdirAttachmentAlias::new("checkout").unwrap();
+    router
+        .attach(
+            alias.clone(),
+            Arc::new(LocalWorkdirSession::new(
+                scope_with_spill(first.path(), spill.path()),
+                first.path().to_path_buf(),
+            )),
+        )
+        .unwrap();
+    let reg = Registry::new(routed_builtin_tools(
+        router.clone(),
+        Tracker::new(),
+        spill.path().to_path_buf(),
+    ));
+    call(
+        &reg.get("Read"),
+        json!({ "target_workdir": "checkout", "file_path": "same.txt" }),
+    )
+    .await;
+
+    router.detach(&alias).await.unwrap();
+    router
+        .attach(
+            alias.clone(),
+            Arc::new(LocalWorkdirSession::new(
+                scope_with_spill(second.path(), spill.path()),
+                second.path().to_path_buf(),
+            )),
+        )
+        .unwrap();
+
+    let error = call_err(
+        &reg.get("Edit"),
+        json!({
+            "target_workdir": "checkout",
+            "file_path": "same.txt",
+            "old_string": "same",
+            "new_string": "changed"
+        }),
+    )
+    .await;
+    assert!(error.to_string().contains("has not been read"), "{error}");
+    assert_eq!(
+        std::fs::read_to_string(second.path().join("same.txt")).unwrap(),
+        "same bytes\n"
+    );
+
+    router.close_all().await.unwrap();
+}
+
 #[tokio::test]
 async fn view_image_reads_scoped_bytes_into_durable_tool_detail() {
     let dir = TempDir::new().unwrap();