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ELEMENT 31

Local Bridge

Local Bridge is the Substrate service that connects the appliance to on-premise systems over routes the site has explicitly declared. No default path to the public internet exists.

· 2 min read

IN SHORT

Local Bridge is the Substrate service that provides policy-governed connectivity between the appliance and on-premise systems the site already secures. Every connection is a route the site explicitly declared, carrying a policy for what may cross it. No default path to the public internet exists, and a site that declares no routes is air-gapped.

Local Bridge is the Substrate service that connects the appliance to on-premise systems over explicitly declared, policy-governed routes. It is the only path from Substrate to anything outside its enclosure, and no default path to the public internet exists.

Why it matters

Serving a facility usually means touching the systems it already runs. Retrieval needs the site's documents. Applications want to hand results to the warehouse system or publish events on the plant bus. Without a controlled way to do this, a platform either stays useless or sprawls into every system it can find. Local Bridge is the controlled way.

Its significance is as much in what it refuses as in what it permits. Because every route is declared, the site can list exactly which systems the appliance can reach. Because there is no default path, the question of what leaves the building has a short, enforceable answer. A connection on Substrate is a decision the site made, not a default the platform assumed.

How it works here

A route is declared by someone with authority on the site. It names one on-premise system, the direction of traffic, and a policy for what kind of exchange is permitted. Routes are written into the platform's configuration where they can be listed and reviewed. An attempted connection that matches no declared route is refused, and the refusal is recorded alongside the Evaluation traces.

Posture follows from the routes. A site that declares none is air-gapped: every Substrate service runs, with nothing reaching out. A site that declares routes to the systems it already secures is connected, to those systems and nothing else. A mixed estate runs both postures on the same platform, with each building making its own declaration.

The far end of every route is inside the site's own perimeter. That is why a connected site still keeps everything in the building: data moves between two systems the site owns, over a path the site declared, within walls the site controls.

  • Substrate: the platform Local Bridge is part of.
  • Watchman: the integrity service that confirms the platform is intact.
  • Inference service: the serving service whose results routes may carry.
  • Latency budget: what callers declare on the facility network.

Questions this raises

What kinds of systems do routes typically reach?
A document store that Retrieval reads from, a warehouse or plant system that receives results, or a message bus on the plant segment that applications publish to and subscribe from. All are systems the site already runs inside its own perimeter.
Can a route be removed later?
Yes. Routes are configuration the site owns. Removing one withdraws the connection without changing anything else on the platform, and the route's history remains in the record.
Does Local Bridge connect to the customer portal?
No. Appliances never connect to the portal, and Local Bridge has no route to it. The portal is where the customer downloads bundles and requests sessions; nothing on the appliance reaches it.

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