Architecture
One definition, many surfaces
A dendra procedure is a small, immutable spec: an optional input schema, an optional output schema, middleware, an HTTP method/path (optional), and a handler. From that one spec, dendra projects every surface — they can’t drift, because they all derive from the same definition.
▶ Open the interactive framework diagram
| Surface | Produced by |
|---|---|
| Typed client (no codegen) | createClient<AppRouter>() — inference over typeof appRouter |
| In-process caller | createCaller(appRouter, ctx) |
| REST + OpenAPI 3.1 | toRestHandler, toOpenApiDocument |
| RPC over HTTP | toNextHandler, toFetchHandler, toNodeHandler |
| Streaming (NDJSON) & WebSocket | route.stream(...) + the adapters |
| LLM tool | .ai() + toToolset / createToolExecutor |
| MCP server | mcpToolDefinitions / createMcpBridge |
Change the input schema and the client type, the REST validation, the OpenAPI entry, and the tool schema all change together.
A real app
The example app wires dendra into a multi-tenant Next.js notes app: the browser
and Claude both talk to the same appRouter, which uses SQLite, pub/sub,
runAgent, and an MCP connection registry with OAuth.
▶ Open the interactive example diagram
The framework ↔ app boundary
Would every dendra user want this regardless of their DB, auth, UI, or which servers they connect to? Yes → framework. No → app.
The app owns, and dendra never touches: authentication, UI/navigation, voice, and MCP connection management (transports, a connection registry, OAuth to remote servers). dendra provides only the typed-procedure and tool-shaping primitives — which is why the core stays zero-dependency.
Validation as the guardrail
Input validation runs before every handler — over HTTP, in-process, and when the model calls a tool. The same schema that rejects a bad REST body rejects a bad tool call, so model output is guarded by the same contract as everything else.
Context
createContext(req) builds the per-request ctx (auth, tenant, db, pubsub,
memory). Handlers read ctx; middleware (.use()) refines it. Swap the HTTP
adapter for a WebSocket or test adapter and tenancy/auth still work, because every
adapter builds ctx the same way.