> ## Documentation Index > Fetch the complete documentation index at: https://docs.fabro.sh/llms.txt > Use this file to discover all available pages before exploring further. # Concurrency limits, SSH access, and timer nodes ## Concurrency limiter Set `max_concurrent_runs` in server config to control how many runs execute simultaneously. Additional start-requested runs wait as `runnable` before moving to `starting`, with both states visible in the UI and API. Previously, starting too many runs at once could overwhelm the machine. Now excess runs wait in a queue and start as capacity frees up. ## SSH access to running sandboxes Use `fabro ssh ` to get SSH access into running Daytona sandboxes for live debugging while the workflow executes. When something goes wrong mid-run, you can drop into the sandbox, inspect the filesystem, and understand the problem without waiting for the run to finish. Use `--preserve-sandbox` to keep sandboxes alive after a run completes for post-mortem inspection. ## Timer nodes Add `wait.timer` nodes to workflows that pause for a configured duration. Useful for rate limiting between API calls or waiting for external processes to complete. ## More * All list endpoints now support offset-based pagination with `offset` and `limit` parameters * New `GET /usage` endpoint returns aggregate token counts and estimated costs broken down by model * Hot config reload — changes to `server.toml` are detected and applied without restarting the server * All error responses now use a consistent JSON structure with error codes and messages * Fixed HTTP 529 (Overloaded) responses from LLM providers being misclassified as non-retryable * Fixed progress display panic when tool calls contain long whitespace sequences * Gemini 3.1 Flash Lite added to the model catalog for ultra-fast, low-cost tasks * Multi-provider ensemble demo workflow showing fan-out across models and result merging * Parallel branches show in progress UI; sandbox details with hyperlinks display during runs