[ Native macOS control plane ]Source preview available

Give agentsa boundarythey can’t ignore.

Fulmar turns DeepSeek Harness into a native Mac workspace with visible permissions, guarded tools and model routes you choose—local, cloud or a compatible endpoint.

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// MODEL ROUTING

Your model. Your choice.

LOCAL / CLOUD / CUSTOMBOUNDARY / EXPLICIT

// DSH, MADE DELIBERATE

The agent runtime is powerful. Fulmar makes that power legible.

DeepSeek Harness supplies the agent loop, tools, sessions, skills and plugins. Fulmar supplies the trusted Mac control plane around it: process ownership, exact network destinations, Keychain-backed credentials, workspace confinement and a visible approval surface.

// FOUR NON-NEGOTIABLES

Power, with edges.

“Local”, “approved” and “inside the project” are enforced operating decisions—not reassuring labels placed on an unrestricted agent.

For its local route, Fulmar starts and verifies the runtime process it uses, lets you choose from its safely catalogued installed models, gives DSH one exact loopback origin, and blocks unrelated network egress.

APP-OWNED LOCAL RUNTIME / LOOPBACK ONLY

// THE CONTROL PATH

DSH does the work. Fulmar controls the conditions.

01 / INTENTYou

Choose a task, route and access level.

VISIBLE CONTROL

02 / AUTHORITYFulmar

Owns policy, lifecycle, consent and recovery.

AUTHENTICATED LOOPBACK

03 / AGENT LOOPDSH

Runs sessions, tools, skills and plugins.

04A / LOCALA compatible model on this Mac

Verified local runtime · cloud egress blocked

04B / CONNECTEDA supported provider route

One consented origin · fresh context

// PROVIDER-NEUTRAL BY DESIGN

The model is a route.
Not the product.

Fulmar reads DSH’s live provider and model catalogue, then applies the consent, credential and network boundary required by the route you select. No single model brand defines the product.

01 / LOCAL ROUTE

Compatible models on this Mac

Choose a safely catalogued installed model exposed by Fulmar’s supported local runtime.

STRICT LOCAL / NO CLOUD KEY

02 / HOSTED ROUTE

Supported cloud providers

Use your own credential. Fulmar opens egress only to the exact provider origin you approve.

KEYCHAIN / FRESH SESSION

03 / CUSTOM ROUTE

Your compatible endpoint

Add an endpoint that speaks a supported protocol, then declare the models and capabilities it exposes.

CUSTOM ROUTE / FAILS CLOSED

Provider-neutral does not mean every model works automatically. Compatibility depends on the provider protocol, the model’s tool capabilities and route-specific testing. The public support matrix distinguishes tested routes, protocol simulations and unqualified configurations.

// PLUGINS ARE EXTENSION POINTS

DSH is built to be composed.

Models, tools, files, sessions, agents and UI sit behind plugin interfaces. Fulmar selects and constrains that composition instead of rebuilding the agent loop—or granting every extension unlimited authority.

EXAMPLE / SAFE PAGE FETCHFULMAR PLUGIN

01The model names one public HTTPS page.
02Fulmar shows the exact URL for approval.
03A short-lived capability opens only that host.
04Redirects, private IPs and binary bodies are refused.
05The capability disappears after the response.

$ fulmar / web_fetchALLOW_ONCEorigin: https://example.orgredirects: denyprivate_network: denyexpires: response_end

// NATIVE CONTROL PLANE

Not a browser wrapper.

The visible app and the policy underneath it are one product. Every native surface exists to make the agent’s state, cost and authority easier to see.

[01]

Native Quick Chat

Real DSH sessions with streaming, approvals, attachments, voice and cancellation.

[02]

Keychain credentials

Configuration stores references; provider secret values resolve only when needed.

[03]

Guarded Skills + MCP

Reviewed content is fingerprinted, scoped and revoked when its bytes change.

[04]

Thermal protection

Local inference adapts to pressure without imposing arbitrary cloud limits.

[05]

Task History

Continue, branch, rename, archive and export without silently changing the route.

[06]

Workspace Recovery

Preview and reverse agent changes with stale-state and conflict protection.

[07]

Schedules + Inbox

Unattended work has explicit provider consent, bounded retention and visible outcomes.

[08]

Release evidence

Pinned runtime, inventories, SBOM, hostile-input tests and deterministic rollback.

// WHAT CONTROL LOOKS LIKE

One glance should answer: where is this going?

Model, privacy boundary, access mode and runtime health stay visible while the agent works. A boundary change is a transaction, not a casual dropdown.

Fulmar — Agent WorkspaceREADY · ON THIS MAC

Check the project, fix the failing test and keep everything local.

FULMAR AGENTI found one failing workspace recovery test. I can inspect the relevant files and run the targeted suite inside the Workspace.

APPROVAL REQUIREDRun targeted Swift tests?swift test --filter WorkspaceRecoveryTests

DENYALLOW ONCE

// REVIEW STATUS / CLAIMS NEED RECEIPTS

OPENMIT-licensed source is available to inspect and build on GitHub

SCOPEDprotocol fixtures and local tests do not become universal provider claims

GATEDa supported app download waits for signing, notarisation and clean-Mac qualification

Read the current release-readiness record and support matrix for the evidence and limitations behind the source preview.

SOURCE PREVIEW / MIT LICENSE

The source is open.
Start on GitHub.

Inspect the source, build Fulmar on your Apple-silicon Mac, or help test the preview. The repository includes setup instructions, requirements and known limitations. A supported DMG or ready-to-install app is not available yet; source builds are locally signed and are not Apple-notarised.

View source ↗Build from source ↗Getting started ↗

// STRAIGHT ANSWERS

Before you ask.

What is DeepSeek Harness (DSH)?

DeepSeek Harness is an open-source agent runtime, not an LLM. It connects a model to tools, skills, sessions, storage, agent loops, scheduling and a user interface through replaceable plugin interfaces.

What is Fulmar?

Fulmar is an independent native macOS control plane built around a pinned DeepSeek Harness runtime. It makes the selected model route, tools, permissions, workspace boundary and recovery state visible and deliberate.

Is Fulmar just a desktop wrapper for DSH?

No. A wrapper mainly puts an existing web interface in a window. Fulmar is designed to own the runtime lifecycle, credential references, route-specific network access, approvals, workspace confinement and recovery as part of the native Mac product.

Can Fulmar use any LLM?

Not literally any model, but Fulmar is not tied to one model brand. A model must be exposed by a supported local runtime, built-in cloud route or compatible endpoint, match the protocol and tool capabilities DSH needs, and pass route-specific testing.

What data leaves the Mac?

That depends on the route you deliberately select. A qualified local route is designed to keep model traffic on the Mac and block unrelated egress. A hosted or custom route sends the task context needed for that session to the exact provider origin you approve.

Is Fulmar affiliated with DeepSeek?

No. Fulmar is an independent project built around DeepSeek Harness. DeepSeek, provider and model names belong to their respective owners; no affiliation or endorsement is implied.

Can I download Fulmar now?

Fulmar is available as an MIT-licensed source preview on GitHub at github.com/ajss-25/fulmar. You can inspect the code and follow the build-from-source instructions. There is no supported DMG or ready-to-install app download yet, and local builds are not Developer ID signed or Apple-notarised. See the repository for requirements, setup and current limitations.