fix: derive worktree name from path, not branch name

Git worktree names are stored in .git/worktrees/<name> and cannot
contain slashes. The code was using branch names like "feature/slug"
or "rfc/name" as worktree names, which git2 rejects silently.

Now the worktree name is derived from the path's directory name (the
slug), which is always a simple identifier without slashes.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

crates/blue-core/src/repo.rs

@@ -346,6 +346,13 @@ pub fn create_worktree(
     branch_name: &str,
     worktree_path: &Path,
 ) -> Result<(), RepoError> {
+    // Derive worktree name from path (directory name = slug, no slashes)
+    // Git worktree names are stored in .git/worktrees/<name> and cannot contain slashes
+    let worktree_name = worktree_path
+        .file_name()
+        .and_then(|n| n.to_str())
+        .ok_or_else(|| RepoError::Git(git2::Error::from_str("Invalid worktree path")))?;
+
     // Create the branch if it doesn't exist
     let head = repo.head()?;
     let head_commit = head.peel_to_commit()?;
@@ -358,7 +365,7 @@ pub fn create_worktree(
     // Create the worktree
     let reference = branch.into_reference();
     repo.worktree(
-        branch_name,
+        worktree_name,
         worktree_path,
         Some(git2::WorktreeAddOptions::new().reference(Some(&reference))),
     )?;
@@ -366,9 +373,17 @@ pub fn create_worktree(
     Ok(())
 }
 
-/// Remove a worktree
-pub fn remove_worktree(repo: &git2::Repository, name: &str) -> Result<(), RepoError> {
-    let worktree = repo.find_worktree(name)?;
+/// Remove a worktree by path
+///
+/// Derives the worktree name from the path's directory name.
+pub fn remove_worktree(repo: &git2::Repository, worktree_path: &Path) -> Result<(), RepoError> {
+    // Derive worktree name from path (same as create_worktree)
+    let worktree_name = worktree_path
+        .file_name()
+        .and_then(|n| n.to_str())
+        .ok_or_else(|| RepoError::Git(git2::Error::from_str("Invalid worktree path")))?;
+
+    let worktree = repo.find_worktree(worktree_name)?;
 
     // Prune the worktree (this removes the worktree but keeps the branch)
     worktree.prune(Some(

crates/blue-mcp/src/handlers/realm.rs

@@ -701,6 +701,13 @@ fn create_git_worktree(
         return Err("Worktree path already exists".to_string());
     }
 
+    // Derive worktree name from path (directory name = slug, no slashes)
+    // Git worktree names are stored in .git/worktrees/<name> and cannot contain slashes
+    let worktree_name = worktree_path
+        .file_name()
+        .and_then(|n| n.to_str())
+        .ok_or("Invalid worktree path")?;
+
     // Get HEAD commit to branch from
     let head = repo.head().map_err(|e| format!("Failed to get HEAD: {}", e))?;
     let commit = head.peel_to_commit().map_err(|e| format!("Failed to get commit: {}", e))?;
@@ -720,7 +727,7 @@ fn create_git_worktree(
 
     // Create the worktree
     repo.worktree(
-        branch_name,
+        worktree_name,
         worktree_path,
         Some(git2::WorktreeAddOptions::new().reference(Some(&reference))),
     )

crates/blue-mcp/src/handlers/worktree.rs

@@ -380,8 +380,9 @@ pub fn handle_cleanup(state: &ProjectState, args: &Value) -> Result<Value, Serve
     }
 
     // Remove worktree from git
-    let worktree_removed = if worktree.is_some() {
-        blue_core::repo::remove_worktree(&repo, &branch_name).is_ok()
+    let worktree_removed = if let Some(ref wt) = worktree {
+        let wt_path = Path::new(&wt.worktree_path);
+        blue_core::repo::remove_worktree(&repo, wt_path).is_ok()
     } else {
         false
     };
@@ -465,8 +466,9 @@ pub fn handle_remove(state: &ProjectState, args: &Value) -> Result<Value, Server
 
     // Remove from git
     let repo_path = state.home.root.clone();
+    let wt_path = Path::new(&worktree.worktree_path);
     if let Ok(repo) = git2::Repository::open(&repo_path) {
-        if let Err(e) = blue_core::repo::remove_worktree(&repo, &worktree.branch_name) {
+        if let Err(e) = blue_core::repo::remove_worktree(&repo, wt_path) {
             return Ok(json!({
                 "status": "error",
                 "message": blue_core::voice::error(