refactor(server): unify instance httpapi middleware routing

Unify declared instance HTTP API endpoints under typed middleware routing, including event streaming and PTY WebSocket connect handling.\n\nPreserve PTY connect compatibility by checking missing PTYs before parsing optional cursor and ticket query fields, with regression coverage.

packages/opencode/src/server/routes/instance/httpapi/AGENTS.md

@@ -14,18 +14,20 @@ export const sessionHandlers = HttpApiBuilder.group(InstanceHttpApi, "session",
 
 For SSE endpoints, stay in `HttpApiBuilder.group(...)` and return `HttpServerResponse.stream(...)` from the handler. Annotate the endpoint success schema with `HttpApiSchema.asText({ contentType: "text/event-stream" })` so OpenAPI documents the stream content type.
 
-Use raw `HttpRouter.use(...)` only for routes that do not fit the request/response HttpApi model, such as WebSocket upgrade routes or catch-all fallback routes. Yield stable services at route-layer construction and close over them in `router.add(...)` callbacks.
+Use `HttpApiBuilder.group(...)` with `handleRaw(...)` for declared endpoints that need the raw request or response, including WebSocket upgrade routes. This keeps endpoint middleware, routing context, and OpenAPI metadata on one typed route tree.
 
 ```ts
-export const rawRoute = HttpRouter.use((router) =>
+export const ptyConnectHandlers = HttpApiBuilder.group(PtyConnectApi, "pty-connect", (handlers) =>
   Effect.gen(function* () {
     const pty = yield* Pty.Service
 
-    yield* router.add("GET", PtyPaths.connect, (request) => connectPty(request, pty))
+    return handlers.handleRaw("connect", (ctx) => connectPty(ctx.request, pty))
   }),
 )
 ```
 
+Use raw `HttpRouter.use(...)` only for routes outside the declared API surface, such as a catch-all UI fallback.
+
 Avoid `Effect.provide(SomeLayer)` inside request handlers or raw route callbacks. Stable layers should be provided once at the application/layer boundary, not rebuilt or scoped per request.
 
 Avoid `HttpRouter.provideRequest(...)` unless the dependency is intentionally request-level. Prefer `HttpRouter.use(...)` for stable app services.
@@ -34,4 +36,4 @@ Use `Effect.provideService(...)` in middleware only for request-derived context,
 
 Public JSON errors should be explicit `Schema.ErrorClass` contracts declared on each endpoint. Use built-in `HttpApiError.*` classes only when their empty/tagged body is the intended wire shape; for SDK-visible errors with messages, define an API error schema such as `ApiNotFoundError` and fail with that exact declared error. Keep domain and storage services free of HttpApi types, and translate expected domain errors at the handler boundary.
 
-When adding middleware, compose it at the layer boundary and keep the route tree explicit in `server.ts`. Shared router middleware such as auth, workspace routing, and instance context should stay visible where routes are assembled.
+When adding middleware, declare endpoint-contract middleware on the owning `HttpApiGroup` and provide its implementation layer at the assembly boundary in `server.ts`. Keep router middleware for truly raw fallback routes or global transport policy.