serena-project-activate

Serena Project Activation

Activate an already-registered Serena project for the current session so that semantic coding tools become available.

When to Use

This skill applies when:

• The project already has a .serena/project.yml configuration file (already registered)
• get_current_config returns "No active project" error
• Serena MCP tools fail or return errors at session start
• The user explicitly asks to activate or start Serena

If .serena/project.yml does not exist, the project is not yet registered. Use the serena-project-init skill instead to perform full registration.

Why Activation Is Per-Session

Serena separates registration from activation by design:

• Registration (via CLI serena project create) is persistent — it writes .serena/project.yml to disk and only needs to happen once.
• Activation (via activate_project MCP tool) is an in-memory operation — it must happen each time a new session starts with the Serena MCP server.

This means every new conversation or session requires calling activate_project before any other Serena tools will work.

Activation Workflow

Step 1: Identify the Project

Determine the project name or path. Options:

• Use the registered project name from .serena/project.yml (the project_name field)
• Use the absolute path to the project directory
• Call get_current_config — it lists known projects by name in its error message

Step 2: Activate the Project

Call the activate_project MCP tool:

activate_project(project="<project-name-or-path>")

Either the registered project name or the absolute directory path works. On success, all Serena semantic tools become available.

Step 3: Verify Activation

Call get_current_config to confirm the project is now active. A successful response returning configuration data (rather than a "No active project" error) confirms activation succeeded.

Step 4: Check Onboarding

Call check_onboarding_performed to determine whether onboarding data exists for this project. If onboarding has not been performed, consider running onboarding() to let Serena analyze the project structure, build systems, and testing frameworks.

Troubleshooting

"Project not found" on activate

The project name may not match what was registered. Try:

• Using the absolute path instead of the project name
• Checking .serena/project.yml for the exact project_name value
• Running get_current_config to see the list of known projects

Activation succeeds but tools still fail

Check that the configured language servers can start:

• Verify the correct language is configured in .serena/project.yml
• Ensure language server dependencies are installed (e.g., pyright for Python, typescript-language-server for TypeScript)

Multiple projects

Only one project can be active at a time. Activating a new project deactivates the previous one. To switch projects, call activate_project with the new project name or path.

Project needs re-registration

If the .serena/project.yml is corrupted or misconfigured, delete it and use the serena-project-init skill to register the project again from scratch.

Cross-Reference

• For initial project registration and setup, use the serena-project-init skill
• For full project configuration options, see the project-config reference in the serena-project-init skill