Preview API

Source: backend/app/api/preview.py

Live preview server management for web projects in the Code Workspace.

Endpoints

Detect Project Type

GET /api/preview/detect?workspace_dir=/path/to/project

Scans the workspace directory and returns the detected project type and start command.

Response:

{
  "project_type": "vite",
  "command": "npm run dev",
  "package_manager": "npm",
  "detected_from": "package.json devDependencies"
}

Possible project_type values: vite, nextjs, cra, nuxt, svelte, astro, flask, fastapi, static, unknown.

Start Preview Server

POST /api/preview/start

Body:

{
  "workspace_dir": "/path/to/project",
  "command": "npm run dev"
}

If command is omitted, the server auto-detects the project type and chooses the appropriate start command. Picks a free port in the 3100-3199 range.

Response:

{
  "status": "started",
  "port": 3142,
  "pid": 12345,
  "project_type": "vite"
}

Stop Preview Server

POST /api/preview/stop

Stops the running preview server process.

Response:

{
  "status": "stopped"
}

Server Status

GET /api/preview/status

Returns whether a preview server is running.

Response:

{
  "running": true,
  "port": 3142,
  "pid": 12345,
  "project_type": "vite",
  "uptime_seconds": 45.2
}

Server Logs

GET /api/preview/logs

Returns recent stdout/stderr output from the preview server process.

Query parameters:

Parameter	Type	Default	Description
lines	int	50	Maximum number of log lines to return

Response:

{
  "logs": [
    {"timestamp": "2026-03-23T14:30:00", "line": "VITE v6.2.0 ready in 312 ms"},
    {"timestamp": "2026-03-23T14:30:00", "line": "Local: http://localhost:3142/"}
  ]
}

Notes

• Only one preview server runs at a time. Starting a new one stops the previous.
• The preview server process is killed when the workspace changes or the app closes.
• Port selection avoids conflicts with the backend (8000+) and Electron dev server (5173).
• Server logs use a ring buffer (last 500 lines).