agent_panel: Add new thread git worktree/branch pickers

crates/agent_ui/src/agent_ui.rs

@@ -28,13 +28,16 @@ mod terminal_codegen;
 mod terminal_inline_assistant;
 #[cfg(any(test, feature = "test-support"))]
 pub mod test_support;
+mod thread_branch_picker;
 mod thread_history;
 mod thread_history_view;
 mod thread_import;
 pub mod thread_metadata_store;
+mod thread_worktree_picker;
 pub mod threads_archive_view;
 mod ui;
 
+use std::path::PathBuf;
 use std::rc::Rc;
 use std::sync::Arc;
 
@@ -314,16 +317,42 @@ impl Agent {
     }
 }
 
+/// Describes which branch to use when creating a new git worktree.
+#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize, JsonSchema)]
+#[serde(rename_all = "snake_case", tag = "kind")]
+pub enum NewWorktreeBranchTarget {
+    /// Create a new randomly named branch from the current HEAD.
+    /// Will match worktree name if the newly created worktree was also randomly named.
+    #[default]
+    CurrentBranch,
+    /// Check out an existing branch, or create a new branch from it if it's
+    /// already occupied by another worktree.
+    ExistingBranch { name: String },
+    /// Create a new branch with an explicit name, optionally from a specific ref.
+    CreateBranch {
+        name: String,
+        #[serde(default)]
+        from_ref: Option<String>,
+    },
+}
+
 /// Sets where new threads will run.
-#[derive(
-    Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize, JsonSchema, Action,
-)]
+#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize, JsonSchema, Action)]
 #[action(namespace = agent)]
 #[serde(rename_all = "snake_case", tag = "kind")]
 pub enum StartThreadIn {
     #[default]
     LocalProject,
-    NewWorktree,
+    NewWorktree {
+        /// When this is None, Zed will randomly generate a worktree name
+        /// otherwise, the provided name will be used.
+        #[serde(default)]
+        worktree_name: Option<String>,
+        #[serde(default)]
+        branch_target: NewWorktreeBranchTarget,
+    },
+    /// A linked worktree that already exists on disk.
+    LinkedWorktree { path: PathBuf, display_name: String },
 }
 
 /// Content to initialize new external agent with.

crates/agent_ui/src/conversation_view/thread_view.rs

@@ -869,7 +869,10 @@ impl ThreadView {
                 .upgrade()
                 .and_then(|workspace| workspace.read(cx).panel::<AgentPanel>(cx))
                 .is_some_and(|panel| {
-                    panel.read(cx).start_thread_in() == &StartThreadIn::NewWorktree
+                    !matches!(
+                        panel.read(cx).start_thread_in(),
+                        StartThreadIn::LocalProject
+                    )
                 });
 
         if intercept_first_send {