Restore tool cards on thread deserialization (#30053)

Release Notes:

- N/A

---------

Co-authored-by: Julia Ryan <juliaryan3.14@gmail.com>

crates/assistant_tool/src/assistant_tool.rs

@@ -7,6 +7,7 @@ mod tool_working_set;
 use std::fmt;
 use std::fmt::Debug;
 use std::fmt::Formatter;
+use std::ops::Deref;
 use std::sync::Arc;
 
 use anyhow::Result;
@@ -61,11 +62,34 @@ impl ToolUseStatus {
     }
 }
 
+#[derive(Debug)]
+pub struct ToolResultOutput {
+    pub content: String,
+    pub output: Option<serde_json::Value>,
+}
+
+impl From<String> for ToolResultOutput {
+    fn from(value: String) -> Self {
+        ToolResultOutput {
+            content: value,
+            output: None,
+        }
+    }
+}
+
+impl Deref for ToolResultOutput {
+    type Target = String;
+
+    fn deref(&self) -> &Self::Target {
+        &self.content
+    }
+}
+
 /// The result of running a tool, containing both the asynchronous output
 /// and an optional card view that can be rendered immediately.
 pub struct ToolResult {
     /// The asynchronous task that will eventually resolve to the tool's output
-    pub output: Task<Result<String>>,
+    pub output: Task<Result<ToolResultOutput>>,
     /// An optional view to present the output of the tool.
     pub card: Option<AnyToolCard>,
 }
@@ -128,9 +152,9 @@ impl AnyToolCard {
     }
 }
 
-impl From<Task<Result<String>>> for ToolResult {
+impl From<Task<Result<ToolResultOutput>>> for ToolResult {
     /// Convert from a task to a ToolResult with no card
-    fn from(output: Task<Result<String>>) -> Self {
+    fn from(output: Task<Result<ToolResultOutput>>) -> Self {
         Self { output, card: None }
     }
 }
@@ -187,6 +211,16 @@ pub trait Tool: 'static + Send + Sync {
         window: Option<AnyWindowHandle>,
         cx: &mut App,
     ) -> ToolResult;
+
+    fn deserialize_card(
+        self: Arc<Self>,
+        _output: serde_json::Value,
+        _project: Entity<Project>,
+        _window: &mut Window,
+        _cx: &mut App,
+    ) -> Option<AnyToolCard> {
+        None
+    }
 }
 
 impl Debug for dyn Tool {