Accept story 38: Auto-Open Project on Server Startup

Server detects .story_kit/ in cwd or parent directories at startup and
automatically opens the project. MCP tools work immediately without
manual project-open step. Falls back to cwd when no .story_kit/ found.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/main.rs

@@ -41,14 +41,49 @@ fn remove_port_file(path: &Path) {
     let _ = std::fs::remove_file(path);
 }
 
+/// Walk from `start` up through parent directories, returning the first
+/// directory that contains a `.story_kit/` subdirectory, or `None`.
+fn find_story_kit_root(start: &Path) -> Option<PathBuf> {
+    let mut current = start.to_path_buf();
+    loop {
+        if current.join(".story_kit").is_dir() {
+            return Some(current);
+        }
+        if !current.pop() {
+            return None;
+        }
+    }
+}
+
 #[tokio::main]
 async fn main() -> Result<(), std::io::Error> {
     let app_state = Arc::new(SessionState::default());
     let cwd = std::env::current_dir().unwrap_or_else(|_| PathBuf::from("."));
-    *app_state.project_root.lock().unwrap() = Some(cwd.clone());
     let store = Arc::new(
         JsonFileStore::from_path(PathBuf::from("store.json")).map_err(std::io::Error::other)?,
     );
+
+    // Auto-detect a .story_kit/ project in cwd or parent directories.
+    if let Some(project_root) = find_story_kit_root(&cwd) {
+        io::fs::open_project(
+            project_root.to_string_lossy().to_string(),
+            &app_state,
+            store.as_ref(),
+        )
+        .await
+        .unwrap_or_else(|e| {
+            eprintln!("Warning: failed to auto-open project at {project_root:?}: {e}");
+            project_root.to_string_lossy().to_string()
+        });
+
+        // Validate agent config for the detected project root.
+        config::ProjectConfig::load(&project_root)
+            .unwrap_or_else(|e| panic!("Invalid project.toml: {e}"));
+    } else {
+        // No .story_kit/ found — fall back to cwd so existing behaviour is preserved.
+        *app_state.project_root.lock().unwrap() = Some(cwd.clone());
+    }
+
     let workflow = Arc::new(std::sync::Mutex::new(WorkflowState::default()));
     let port = resolve_port();
     let agents = Arc::new(AgentPool::new(port));
@@ -70,10 +105,6 @@ async fn main() -> Result<(), std::io::Error> {
     println!("\x1b[96;1mFrontend:\x1b[0m \x1b[94mhttp://{addr}\x1b[0m");
     println!("\x1b[92;1mOpenAPI Docs:\x1b[0m \x1b[94mhttp://{addr}/docs\x1b[0m");
 
-    // Validate agent config at startup — panic on invalid project.toml.
-    config::ProjectConfig::load(&cwd)
-        .unwrap_or_else(|e| panic!("Invalid project.toml: {e}"));
-
     let port_file = write_port_file(&cwd, port);
 
     let result = Server::new(TcpListener::bind(&addr)).run(app).await;
@@ -136,4 +167,45 @@ name = "coder"
         remove_port_file(&path);
         assert!(!path.exists());
     }
+
+    #[test]
+    fn find_story_kit_root_returns_cwd_when_story_kit_in_cwd() {
+        let tmp = tempfile::tempdir().unwrap();
+        std::fs::create_dir_all(tmp.path().join(".story_kit")).unwrap();
+
+        let result = find_story_kit_root(tmp.path());
+        assert_eq!(result, Some(tmp.path().to_path_buf()));
+    }
+
+    #[test]
+    fn find_story_kit_root_returns_parent_when_story_kit_in_parent() {
+        let tmp = tempfile::tempdir().unwrap();
+        std::fs::create_dir_all(tmp.path().join(".story_kit")).unwrap();
+        let child = tmp.path().join("subdir").join("nested");
+        std::fs::create_dir_all(&child).unwrap();
+
+        let result = find_story_kit_root(&child);
+        assert_eq!(result, Some(tmp.path().to_path_buf()));
+    }
+
+    #[test]
+    fn find_story_kit_root_returns_none_when_no_story_kit() {
+        let tmp = tempfile::tempdir().unwrap();
+        // No .story_kit/ created
+
+        let result = find_story_kit_root(tmp.path());
+        assert_eq!(result, None);
+    }
+
+    #[test]
+    fn find_story_kit_root_prefers_nearest_ancestor() {
+        // If both cwd and a parent have .story_kit/, return cwd (nearest).
+        let tmp = tempfile::tempdir().unwrap();
+        std::fs::create_dir_all(tmp.path().join(".story_kit")).unwrap();
+        let child = tmp.path().join("inner");
+        std::fs::create_dir_all(child.join(".story_kit")).unwrap();
+
+        let result = find_story_kit_root(&child);
+        assert_eq!(result, Some(child));
+    }
 }