FE-1497: Build the controller read path and the SDCPN plugin package

apps/brunch-agent/package.json

@@ -21,6 +21,7 @@
     "@hashintel/brunch-agent": "workspace:*",
     "@hashintel/brunch-agent-binding-flue": "workspace:*",
     "@hashintel/brunch-agent-plugin-gherkin": "workspace:*",
+    "@hashintel/brunch-agent-plugin-sdcpn": "workspace:*",
     "@hashintel/brunch-agent-transport-aisdk": "workspace:*",
     "hono": "4.13.2",
     "react": "19.2.6",

apps/brunch-agent/src/agents/sdcpn-elicitor.ts

@@ -0,0 +1,54 @@
+"use agent";
+/**
+ * The SDCPN elicitor (spec §12.5: one agent per target).
+ *
+ * The second entry in the target gallery, and the first whose plugin is a
+ * file: `@hashintel/brunch-agent-plugin-sdcpn` loads `plugin.md` and the
+ * harness reads its three tables (ADR-0006). This module is as thin as the
+ * gherkin one — it mounts harness capability and holds no elicitation
+ * semantics of its own; what the interviewer asks, demands, and treats as
+ * complete all comes from the plugin file through the binding.
+ *
+ * The same three recorded Flue constraints hold here by construction
+ * (spec §10): `'use agent'` is the file's first statement; `agentName` is a
+ * pinned string literal; the tool set is static.
+ */
+
+import { useInitialData, useModel, type AgentProps } from "@flue/runtime";
+import * as v from "valibot";
+
+import { useElicitation } from "@hashintel/brunch-agent-binding-flue";
+import { sdcpn } from "@hashintel/brunch-agent-plugin-sdcpn";
+
+import { createSdcpnElicitationSession } from "../elicitation-session.ts";
+
+/** One definition for the agent and any faux provider alike (see the gherkin elicitor). */
+export const SDCPN_MODEL_ID = "claude-haiku-4-5";
+
+const sdcpnElicitorInitialData = v.object({
+  targetDocumentId: v.pipe(v.string(), v.nonEmpty()),
+});
+
+export function SdcpnElicitor(props: AgentProps) {
+  useModel(`anthropic/${SDCPN_MODEL_ID}`);
+  const initialData =
+    useInitialData<v.InferOutput<typeof sdcpnElicitorInitialData>>();
+  return useElicitation(
+    sdcpn,
+    createSdcpnElicitationSession(props.id, initialData.targetDocumentId),
+  );
+}
+
+/**
+ * Pinned, and never to be edited: conversation storage keys on this literal,
+ * so changing it orphans every existing conversation. Product-prefixed for the
+ * same reason as the gherkin elicitor — agent identities are global per
+ * application and the demo shell mounts this library beside others.
+ */
+SdcpnElicitor.agentName = "brunch-sdcpn-elicitor";
+
+/**
+ * Session→document binding (spec §9.1): `initialData` carries the
+ * target-document id, validated once at creation and immutable thereafter.
+ */
+SdcpnElicitor.initialData = sdcpnElicitorInitialData;

apps/brunch-agent/src/app.ts

@@ -13,9 +13,14 @@ import { createAgentRouter } from "@flue/runtime/routing";
 import { Hono } from "hono";
 
 import { GherkinElicitor } from "./agents/gherkin-elicitor.ts";
+import { SdcpnElicitor } from "./agents/sdcpn-elicitor.ts";
 import { assetHandler } from "./assets.ts";
 import { petrinautChatHandler } from "./petrinaut-chat.ts";
-import { GHERKIN_AGENT_ROUTE, PETRINAUT_CHAT_ROUTE } from "./routes.ts";
+import {
+  GHERKIN_AGENT_ROUTE,
+  PETRINAUT_CHAT_ROUTE,
+  SDCPN_AGENT_ROUTE,
+} from "./routes.ts";
 
 const app = new Hono();
 
@@ -24,6 +29,9 @@ const app = new Hono();
 // share the route constant; Flue still keys storage on the agent's independent,
 // pinned identity.
 app.route(`/agents/${GHERKIN_AGENT_ROUTE}`, createAgentRouter(GherkinElicitor));
+// The SDCPN elicitor is the process-model target (ADR-0006): the plugin file
+// is code the harness loads, and this mount is what FE-1404's run talks to.
+app.route(`/agents/${SDCPN_AGENT_ROUTE}`, createAgentRouter(SdcpnElicitor));
 
 // The application owns the HTTP mount; transport-aisdk owns only request validation
 // and AI SDK stream encoding. No parallel conversation renderer is introduced.

apps/brunch-agent/src/elicitation-session.ts

@@ -7,7 +7,7 @@ import {
   type FlueHistoryReaderOptions,
 } from "@hashintel/brunch-agent-binding-flue";
 
-import { GHERKIN_AGENT_ROUTE } from "./routes.ts";
+import { AGENT_ROUTES, type AgentTarget } from "./routes.ts";
 import { targetDocumentPath } from "./target-document-path.ts";
 
 const appTransport: FlueHistoryReaderOptions["transport"] = async (
@@ -18,7 +18,13 @@ const appTransport: FlueHistoryReaderOptions["transport"] = async (
   return app.fetch(input instanceof Request ? input : new Request(input, init));
 };
 
-export const createGherkinElicitationSession = (
+/**
+ * One session factory per target agent. The history reader resolves
+ * conversations through the agent's own route, so each target gets a
+ * named creator rather than a shared one that guesses the route.
+ */
+const createElicitationSession = (
+  target: AgentTarget,
   sessionId: string,
   targetDocumentId: string,
 ): ElicitationSession => {
@@ -30,9 +36,21 @@ export const createGherkinElicitationSession = (
     captureStore,
     historyReader: createFlueHistoryReader({
       resolveConversationUrl: (id) =>
-        `http://brunch.local/agents/${GHERKIN_AGENT_ROUTE}/${id}`,
+        `http://brunch.local/agents/${AGENT_ROUTES[target]}/${id}`,
       transport: appTransport,
       archive: captureStore,
     }),
   };
 };
+
+export const createGherkinElicitationSession = (
+  sessionId: string,
+  targetDocumentId: string,
+): ElicitationSession =>
+  createElicitationSession("gherkin", sessionId, targetDocumentId);
+
+export const createSdcpnElicitationSession = (
+  sessionId: string,
+  targetDocumentId: string,
+): ElicitationSession =>
+  createElicitationSession("sdcpn", sessionId, targetDocumentId);

apps/brunch-agent/src/routes.ts

@@ -1,5 +1,17 @@
-/** Browser-facing route segment; conversation identity remains the agent's pinned `agentName`. */
+/** Browser-facing route segments; conversation identity remains each agent's pinned `agentName`. */
 export const GHERKIN_AGENT_ROUTE = "gherkin";
+export const SDCPN_AGENT_ROUTE = "sdcpn";
+
+/** One route per target agent; the gallery grows an entry per plugin (spec §13). */
+export const AGENT_ROUTES = {
+  gherkin: GHERKIN_AGENT_ROUTE,
+  sdcpn: SDCPN_AGENT_ROUTE,
+} as const;
+
+export type AgentTarget = keyof typeof AGENT_ROUTES;
+
+export const isAgentTarget = (value: string | null): value is AgentTarget =>
+  value !== null && Object.hasOwn(AGENT_ROUTES, value);
 
 /** Stock `DefaultChatTransport` endpoint used by Petrinaut's local panel. */
 export const PETRINAUT_CHAT_ROUTE = "/api/chat";

apps/brunch-agent/src/ui/chat.tsx

@@ -5,10 +5,18 @@ import * as v from "valibot";
 
 import { FreeTextAffordance } from "@hashintel/brunch-agent";
 
-import { GHERKIN_AGENT_ROUTE } from "../routes.ts";
+import { AGENT_ROUTES, isAgentTarget } from "../routes.ts";
 
 const conversationId = crypto.randomUUID();
 
+// `?target=sdcpn` selects the agent; the gallery is one route per plugin and
+// gherkin remains the default tracer.
+const requestedTarget = new URLSearchParams(window.location.search).get(
+  "target",
+);
+const agentRoute =
+  AGENT_ROUTES[isAgentTarget(requestedTarget) ? requestedTarget : "gherkin"];
+
 function VisibleMessage({ message }: { message: FlueConversationMessage }) {
   if (
     message.display !== "visible" ||
@@ -58,7 +66,7 @@ export function Chat() {
   const client = useMemo(
     () =>
       createFlueClient({
-        url: `/agents/${GHERKIN_AGENT_ROUTE}/${conversationId}`,
+        url: `/agents/${agentRoute}/${conversationId}`,
       }),
     [],
   );

apps/brunch-agent/test/build-artifact.test.ts

@@ -40,13 +40,17 @@ beforeAll(() => {
 
 /** The pinned identity of every agent module in the app, read from source. */
 function declaredAgentIdentities(): string[] {
-  const agentSource = readFileSync(
-    join(DEV_APP, "src/agents/gherkin-elicitor.ts"),
-    "utf8",
-  );
-  return [
-    ...agentSource.matchAll(/\w+\.agentName\s*=\s*(["'])([^"']+)\1/gu),
-  ].map((match) => match[2]!);
+  const agentsDirectory = join(DEV_APP, "src/agents");
+  return readdirSync(agentsDirectory)
+    .filter((entry) => entry.endsWith(".ts"))
+    .flatMap((entry) =>
+      Array.from(
+        readFileSync(join(agentsDirectory, entry), "utf8").matchAll(
+          /\w+\.agentName\s*=\s*(["'])([^"']+)\1/gu,
+        ),
+      ),
+    )
+    .map((match) => match[2]!);
 }
 
 describe("the emitted server bundle", () => {

libs/@hashintel/brunch-agent/README.md

@@ -14,6 +14,8 @@ This directory is its context and agent-session root, not a package workspace:
 - [`packages/binding-flue/`](./packages/binding-flue/) is the Flue binding.
 - [`packages/transport-aisdk/`](./packages/transport-aisdk/) is the AI SDK transport.
 - [`packages/plugin-gherkin/`](./packages/plugin-gherkin/) is the Gherkin target plugin.
+- [`packages/plugin-sdcpn/`](./packages/plugin-sdcpn/) is the SDCPN target plugin: `plugin.md` and its
+  slot-assertion proposal type.
 - [`../../../apps/brunch-agent/`](../../../apps/brunch-agent/) is the remote server and diagnostic
   application.