Elastic storage
for agentic development on Mac
Your agents run in parallel. Your SSD doesn't grow.
Overflow mounts a development volume bigger than the disk under it. Hot code stays local and fast. Everything else expands into encrypted storage.
- api
- t-4821
- t-4822
- t-4790
- datasets
- models
- archives
- t-4788
- On your Mac
Active source, Git metadata and lockfiles are local before your agent starts.
- In encrypted storage
Datasets, large assets and released workspaces move out, and come back when touched.
- Rebuilt, never uploaded
Build output and package caches are reclaimed when space is tight, not backed up.
Every agent you add is another copy of everything.
A worktree per task. A dependency tree per worktree. Build output, model caches, browser state, logs. CPU work parallelises. A soldered SSD does not.
So you stop running four agents and run two. Or you spend Friday afternoon deciding which project's build cache to delete. Neither of those is a storage strategy.
git worktree add ../task-4821
fatal: could not create leading directories: ENOSPC
cargo build --release
error: failed to write to `target/release/build`:
No space left on device (os error 28)
df -h /
Filesystem Size Used Avail Use%
/dev/disk3s1 466G 466G 0.9G 100%Your agent asks for space before it starts.
Not after the build fails. Overflow admits work it can finish, hands back a ready path, and reclaims the space when the task is done.
Reserve
The agent states what the task needs. Overflow either promises the headroom or refuses with a reason it can act on.
Acquire
One command returns a ready absolute path with the working set already local. No mount paths to construct, no cold first build.
Release
The lease ends, the workspace cools, the durable snapshot stays. Nothing is deleted to make room for something else.
overflow workspace acquire \
--project api --task t-4821 \
--reserve 20GB --ttl 4h --json
{
"path": "/Volumes/Overflow/api/t-4821",
"workspace_id": "ws_01J…",
"lease_id": "lease_01J…",
"reservation": { "bytes": 21474836480, "state": "admitted" },
"availability": "ready",
"warnings": []
}Every operation returns versioned JSON. Built to be driven by Claude Code, Codex, Cursor and anything else that can run a command.
A filesystem that knows what your bytes mean.
Generic mounts treat every byte the same. Overflow classifies your data by what losing it would cost, and stores each class differently.
- api/durable · local
- src/durable · local
- Cargo.lockdurable · local
- target/6.2 GBreconstructable
- node_modules/1.8 GBreconstructable
- workspaces/t-4821/durable · leased
- workspaces/t-4790/durable · released
- datasets/traces-2025/480 GBdurable · remote
- .overflow/scratch/ephemeral · 6h
- Durable
- Source, uncommitted work, agent memory, configuration.
- Journalled locally, encrypted and verified remotely. Never evicted before a verified copy exists.
- Reconstructable
- Build output, target/, node_modules, package caches.
- Kept local while useful. Reclaimed when space is needed. Never uploaded.
- Ephemeral
- Logs, temp state, scratch.
- Expires on a declared lifetime.
Unknown data is treated as durable until Overflow can prove otherwise.
It's your source code. We designed for that.
Trust is the product. The rules below are binding invariants in the safety model, not marketing.
Encrypted on your Mac
Content is encrypted before it leaves the machine. The service never needs your plaintext source or your paths.
Nothing leaves until it's safe
Local bytes are only reclaimed once a remote copy has been verified — objects, manifest and snapshot root.
Export whenever you want
A clean machine can restore or export everything without trusting a local index. Leaving is a supported operation, not a support ticket.
No kernel extension
Overflow uses Apple's supported filesystem extension. No kext, no Reduced Security, no macFUSE.
Instead of buying a bigger Mac.
Every alternative is genuinely good at something. None of them can decide which bytes are allowed to leave.
- A bigger Mac
- Fixed at purchase, and expensive. Overflow grows after the fact.
- An external SSD
- Cheap and fast. But you place every file by hand, and your agents can't.
- A cloud dev environment
- Elastic. And you give up local latency, your local tools, your keys and offline work.
- A generic object-storage mount
- Solid technology. It doesn't understand Git, builds, dirty work or agent leases, so it can't decide what may be evicted.
Questions
The ones people ask before they mount their source code on something new.
When can I use it?
Overflow is in active development and not publicly available yet. Join the waitlist and we'll write to you once — when there's a build worth your time. Early access goes out in batches.
Which Macs?
Apple silicon, macOS. Intel Macs, Linux and Windows are not planned.
Do I have to move my repositories?
No. Overflow is a dedicated volume you opt into, project by project. Your home directory is untouched.
What happens if I go offline?
Anything in your local working set keeps working. Overflow refuses work it cannot complete rather than failing halfway through it.
What happens if I stop paying, or you disappear?
Export is a first-class operation and you hold your own recovery material. You can restore everything on a clean machine without us.
Does it work with Claude Code, Codex and Cursor?
Overflow is driven by a command-line interface with versioned JSON output, so anything that can run a command can drive it. Agents are the primary user, not an afterthought.
Room to run every agent at once.
Early access goes out in batches to people running parallel agents on Apple silicon. Tell us you're one of them.