Extensions ("plugins") let anyone build a full-page app that runs inside a Seed site — on the web and in the desktop app
— reads hypermedia data, and signs as the viewer, without ever holding a key. Extensions are themselves hypermedia
documents, so they are signed, versioned and distributed peer-to-peer like everything else on the network.

Site Dashboard extension running inside the Starlight site on the web

Document	Audience	What it covers
what-and-why.md	everyone	Which extensibility type this is, what an extension can and cannot do, and concrete use cases
project-report.md	everyone	Where things stand: scope delivered, how to try it, verification, environment notes, what is not done
design.md	implementers	The normative design: data model, rendering, bridge, security, workflow
developer-guide.md	extension authors	From `pnpm create` to a published, installed extension, with hot reload
bridge-api.md	extension authors	Every SDK method and bridge message, with examples
site-owner-guide.md	site owners	Installing, pinning, updating and removing extensions (desktop + CLI)
cli.md	everyone	`seed-cli extension …` reference
security.md	everyone	Threat model, what the sandbox guarantees, what it does not
testing.md	implementers	How the system is tested and the verification log for this branch
roadmap.md	team	Other extension kinds and what carries over
decisions.md	team	Decision log with rationale

This work implements the Custom Page type from the team's
Types of Extensibility roadmap; see
what-and-why.md for how it maps to the other types.

The example extensions live in /extensions/examples: hello-signer (bridge smoke test),
site-dashboard (read-only site overview), kanban (board state stored in a document, saved by signing).

Source: branch feat/extensions in the Seed repository (docs/extensions); draft pull request: https://github.com/seed-hypermedia/seed/pull/1020.

Installed on this site for testing: /hello (bridge smoke test), /dashboard (read-only site overview), /board (kanban stored in the document at /board).