---
title: "Concurrency limits, SSH access, and timer nodes"
date: "2026-03-04"
---

## Concurrency limiter

Set `max_concurrent_runs` in server config to control how many runs execute simultaneously. Additional runs queue automatically with `queued` and `starting` 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 <run-id>` 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

<Accordion title="API">
- 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
</Accordion>

<Accordion title="Fixes">
- Fixed HTTP 529 (Overloaded) responses from LLM providers being misclassified as non-retryable
- Fixed progress display panic when tool calls contain long whitespace sequences
</Accordion>

<Accordion title="Improvements">
- 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
</Accordion>