fsit
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A filesystem your agents can mount anywhere.

fsit gives every sandbox a real POSIX directory, scoped to one filesystem, with one revocable credential. Your keys never enter the sandbox.

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Paste into your coding agent
Mount our fsit filesystem: read the fsit docs at /llms.txt, run `fsit login`, then `fsit mount FS_ID ./work` and keep project files in ./work.

Create a mount session from your backend

Your backend holds the API key. It asks fsit for a session on one filesystem and gets a one-time ticket, valid for five minutes.

backend
curl -X POST https://$FSIT_HOST/api/v1/mount-sessions \
  -H "Authorization: Bearer $FSIT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"filesystem_id": "k5q2ztr4mvd7wn3xa6jhebcyfu",
       "mode": "rw", "idempotency_key": "job-4182"}'

{"id": "…", "ticket": "fsittk_…", "state": "requested", …}

Mount it in the sandbox

The sandbox receives only the ticket, on stdin. It is exchanged once for a short-lived session certificate; then it is an ordinary directory.

sandbox
$ echo "$TICKET" | fsit mount --ticket-stdin /mnt/work &
$ cd /mnt/work && git clone https://github.com/acme/app && cd app
$ npm install

Read-only or read-write, per session

Grants cover a whole filesystem. Each session picks its mode up to the grant: write from your laptop while a reviewer agent only reads.

modes
$ fsit mount --ro k5q2ztr4mvd7wn3xa6jhebcyfu review &
$ touch review/notes.md
touch: cannot touch 'review/notes.md': Read-only file system

Revoke a session at any time

Revoke from the console or the API. No new operation is admitted more than 15 seconds later, and the mount ends.

revoke
curl -X DELETE https://$FSIT_HOST/api/v1/mount-sessions/$SESSION_ID \
  -H "Authorization: Bearer $FSIT_API_KEY"

# in the sandbox
fsit: the mount session was revoked or expired; unmounting

What people mount

  • Coding agents

    Give each agent run a workspace that outlives its sandbox.

  • Shared datasets

    Mount the same files read-only into many sandboxes at once.

  • Hand-offs

    One agent writes, the next one picks up exactly where it stopped.

  • Human review

    Mount an agent's filesystem on your laptop and look around.

  • Ephemeral compute

    Keep state off the machine; throw the machine away.

  • Least privilege

    One credential per sandbox, scoped to one filesystem, revocable.

Read the docs