feat(agent):Supports custom agent and chat experience with refactoring (#957)

* feat: add agent management functionality with creation, editing, and deletion

* feat: enhance agent creation and chat experience

- Added AgentWelcome component to display agent description on new thread creation.
- Improved agent name validation with availability check during agent creation.
- Updated NewAgentPage to handle agent creation flow more effectively, including enhanced error handling and user feedback.
- Refactored chat components to streamline message handling and improve user experience.
- Introduced new bootstrap skill for personalized onboarding conversations, including detailed conversation phases and a structured SOUL.md template.
- Updated localization files to reflect new features and error messages.
- General code cleanup and optimizations across various components and hooks.

* Refactor workspace layout and agent management components

- Updated WorkspaceLayout to use useLayoutEffect for sidebar state initialization.
- Removed unused AgentFormDialog and related edit functionality from AgentCard.
- Introduced ArtifactTrigger component to manage artifact visibility.
- Enhanced ChatBox to handle artifact selection and display.
- Improved message list rendering logic to avoid loading states.
- Updated localization files to remove deprecated keys and add new translations.
- Refined hooks for local settings and thread management to improve performance and clarity.
- Added temporal awareness guidelines to deep research skill documentation.

* feat: refactor chat components and introduce thread management hooks

* feat: improve artifact file detail preview logic and clean up console logs

* feat: refactor lead agent creation logic and improve logging details

* feat: validate agent name format and enhance error handling in agent setup

* feat: simplify thread search query by removing unnecessary metadata

* feat: update query key in useDeleteThread and useRenameThread for consistency

* feat: add isMock parameter to thread and artifact handling for improved testing

* fix: reorder import of setup_agent for consistency in builtins module

* feat: append mock parameter to thread links in CaseStudySection for testing purposes

* fix: update load_agent_soul calls to use cfg.name for improved clarity

* fix: update date format in apply_prompt_template for consistency

* feat: integrate isMock parameter into artifact content loading for enhanced testing

* docs: add license section to SKILL.md for clarity and attribution

* feat(agent): enhance model resolution and agent configuration handling

* chore: remove unused import of _resolve_model_name from agents

* feat(agent): remove unused field

* fix(agent): set default value for requested_model_name in _resolve_model_name function

* feat(agent): update get_available_tools call to handle optional agent_config and improve middleware function signature

---------

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

backend/src/config/paths.py

@@ -15,6 +15,12 @@ class Paths:
     Directory layout (host side):
         {base_dir}/
         ├── memory.json
+        ├── USER.md          <-- global user profile (injected into all agents)
+        ├── agents/
+        │   └── {agent_name}/
+        │       ├── config.yaml
+        │       ├── SOUL.md  <-- agent personality/identity (injected alongside lead prompt)
+        │       └── memory.json
         └── threads/
             └── {thread_id}/
                 └── user-data/         <-- mounted as /mnt/user-data/ inside sandbox
@@ -52,6 +58,24 @@ class Paths:
         """Path to the persisted memory file: `{base_dir}/memory.json`."""
         return self.base_dir / "memory.json"
 
+    @property
+    def user_md_file(self) -> Path:
+        """Path to the global user profile file: `{base_dir}/USER.md`."""
+        return self.base_dir / "USER.md"
+
+    @property
+    def agents_dir(self) -> Path:
+        """Root directory for all custom agents: `{base_dir}/agents/`."""
+        return self.base_dir / "agents"
+
+    def agent_dir(self, name: str) -> Path:
+        """Directory for a specific agent: `{base_dir}/agents/{name}/`."""
+        return self.agents_dir / name.lower()
+
+    def agent_memory_file(self, name: str) -> Path:
+        """Per-agent memory file: `{base_dir}/agents/{name}/memory.json`."""
+        return self.agent_dir(name) / "memory.json"
+
     def thread_dir(self, thread_id: str) -> Path:
         """
         Host path for a thread's data: `{base_dir}/threads/{thread_id}/`
@@ -64,10 +88,7 @@ class Paths:
                         or `..`) that could cause directory traversal.
         """
         if not _SAFE_THREAD_ID_RE.match(thread_id):
-            raise ValueError(
-                f"Invalid thread_id {thread_id!r}: only alphanumeric characters, "
-                "hyphens, and underscores are allowed."
-            )
+            raise ValueError(f"Invalid thread_id {thread_id!r}: only alphanumeric characters, hyphens, and underscores are allowed.")
         return self.base_dir / "threads" / thread_id
 
     def sandbox_work_dir(self, thread_id: str) -> Path: