Using Fulminare
Everything you need to point the agent at real work and get it done.
Getting started
Open the app, describe the outcome you want, and press send. Fulminare plans the steps, spins up a machine, and works the task to done — showing you every move in a live timeline. You don't manage tools or steps; you describe the result.
- 1Describe the job as an outcome, not a how-to.
- 2Pick a model (or keep the default).
- 3Watch the plan and tool calls stream in.
- 4Review the result — or flip to Overnight and walk away.
The composer also takes a paperclip attachment (any file — it's copied straight into the sandbox for the agent to read) and, in browsers that support it, a mic button for dictating instead of typing.
Writing great prompts
The best prompts name the outcome and any constraints, and let the agent figure out the rest.
Summarize competitor pricing.
Research the top 5 competitors' pricing, then write a one-page brief with tiers, gaps, and a recommendation.
Fix my repo.
Clone the repo, add a dark-mode toggle to settings, run the tests, and open a PR.
Interactive vs overnight
Interactive keeps you in the loop — great for quick tasks you want to watch and steer. Overnight hands the job off entirely: Fulminare keeps a sandbox alive, works unattended to completion, never blocks for input, and leaves a morning brief. Toggle it in the composer or queue one from the Overnight tab.
Choosing a model
Route each session to the brain that fits the job. Switch anytime — even mid-session.
Fast
High-throughput and cheap — the default for tool-heavy grunt work.
Deep
Heavier reasoning model for the runs that actually need it — costs more, so use it deliberately.
What it can do
Fulminare drives a real machine with the full agentic toolset. You never call these directly — it reaches for the right one on its own.
Maintain a short, living checklist of the steps you'll take.
Run a shell command in the sandbox machine and get stdout/stderr/exit code.
List the entries of a directory in the sandbox.
Read a UTF-8 file from the sandbox.
Create or overwrite a file in the sandbox with the given contents.
Apply a structured diff to create/update/delete files.
Find files by glob pattern, e.
Search file contents with a regex (ripgrep).
Search the live web for current information, docs, or references.
Drive a real headless Chrome inside the sandbox — navigate, click, type, extract page text, or screenshot.
Delegate a self-contained subtask to a parallel sub-agent with its own context.
Surface a file you produced to the user, rendered inline in the app (code, markdown, data).
Generate an image from a text prompt (Gemini image generation).
Expose a service running inside the sandbox (e.
Ask the user to connect a third-party integration (Gmail, Google Calendar, Drive, Slack, Notion, HubSpot, Linear, GitHub) so you can act on their behalf.
Make an authenticated HTTP request to a connected integration's API using the user's stored token (sent as a Bearer token).
Save a durable fact about the user for future sessions (their name, role, preferences, ongoing projects, key people, how they like results).
Search your long-term memory of this user for relevant facts before assuming you don't know something.
Send an interim note to the user without ending your turn (e.
Browser & files panel
When the agent opens a page, a panel slides in on the right with two tabs. Browser shows the live page — real headless Chrome, not a description of one — plus the page's own console output (log/warn/error), so you can actually see what broke if something did. Cookies and logins persist across calls within a session, the same way they would in a normal browser tab.
Files is a read-only, live view of the sandbox filesystem — expand folders, open a file, and it's fetched straight from the running machine, not a cached snapshot. It's the same box the agent is working in, so what you see is exactly what it sees.
Staying in control
Autonomy with receipts. You see every tool call as it happens and can stop the run at any moment. You pick the model and its per-session token budget, and overnight runs flag decisions rather than guessing on anything irreversible.
Each account gets one live sandbox, shared across every session you have open, so context (installed packages, files, running processes) carries over between follow-ups instead of booting fresh each time. It stays warm for 30 minutes of inactivity and closes itself after that — come back later and the next message spins up a clean one.
Integrations
Fulminare works across the apps around the job — and reaches anything else through the browser.
Need something that isn't listed? The agent can request a custom integration mid-run — it asks for a name and an API token right there in the chat, and once you approve it, it's available to every future session the same way a built-in app is.
Memory & personalization
Fulminare remembers. Run the one-time setup in Settings to tell it who you are, what you work on, and how you like things done — it recalls this automatically from message one in every future session, no re-explaining.
It also picks up context as you go: preferences, recurring projects, and decisions you've made stick around in a searchable memory store. You can review or forget anything it's remembered at any time from the same settings panel.
Plans & limits
Fulminare is free — every account gets the same limits: a daily run cap, a weekly token budget, overnight autonomy, and a handful of concurrent live sandboxes. See exact numbers on Pricing. Need more than the shared limits for a team? That's the only thing worth a conversation — reach us from the same page.
Track usage live from the meter in the app sidebar — click it for a full breakdown with reset times. Limits fail open: if a usage check errors, your run still goes through rather than getting blocked.
Keyboard shortcuts
FAQ & troubleshooting
Why is the sandbox taking a moment to start?
Each run boots a real, isolated cloud machine — not a simulation. First boot in a session typically takes a few seconds; Fulminare pools and reuses sandboxes within a session to keep follow-ups fast.
Can I close the tab during an overnight run?
Yes — that's the point. Overnight jobs run unattended on their own sandbox and leave a morning brief when they finish or hit a decision that needs you.
What happens if I hit my plan's limit mid-run?
The current run finishes; limits are enforced when a new run starts, not mid-flight. You'll see exactly what's left in the usage meter before you send.
Does Fulminare keep my files after a session ends?
Anything delivered via present_file is saved to your session and downloadable anytime. The raw sandbox filesystem sticks around too, as long as you keep coming back within 30 minutes — see Staying in control for how sandbox persistence works.
Can I see what the agent's browser is actually doing?
Yes — open the Browser tab in the side panel. It's a live view of a real headless Chrome the agent controls, including the page's own console output, not a text description of what it did.
Something looks wrong or a run seems stuck — what do I do?
Stop the run from the composer and start a fresh session — sandboxes are cheap and isolated per session, so a clean restart never loses prior work. Still stuck? Contact us at fulminare@walnutlabs.in.