From d011447190fd329e8f7f6d505f062875a1aee525 Mon Sep 17 00:00:00 2001
From: shahondin1624 <shahondin1624@gmail.com>
Date: Thu, 12 Mar 2026 11:22:15 +0100
Subject: [PATCH] feat: add gRPC-Web client service layer for
 OrchestratorService

- Create src/lib/services/orchestrator.ts with Connect-Web transport
- Typed processRequest() async generator for server-streaming RPC
- OrchestratorError class mapping gRPC status codes to app errors
- Configurable endpoint with resetTransport() for reconfiguration

Closes #4

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 implementation-plans/_index.md    |  1 +
 implementation-plans/issue-004.md | 25 +++++++++
 src/lib/services/.gitkeep         |  0
 src/lib/services/orchestrator.ts  | 89 +++++++++++++++++++++++++++++++
 4 files changed, 115 insertions(+)
 create mode 100644 implementation-plans/issue-004.md
 delete mode 100644 src/lib/services/.gitkeep
 create mode 100644 src/lib/services/orchestrator.ts

diff --git a/implementation-plans/_index.md b/implementation-plans/_index.md
index c44befd..d905abc 100644
--- a/implementation-plans/_index.md
+++ b/implementation-plans/_index.md
@@ -5,3 +5,4 @@
 | #1    | Project scaffolding: SvelteKit + Tailwind + TypeScript | COMPLETED    | [issue-001.md](issue-001.md) |
 | #2    | Proto codegen pipeline for TypeScript gRPC-Web stubs   | COMPLETED    | [issue-002.md](issue-002.md) |
 | #3    | Configure Caddy for gRPC-Web support                   | COMPLETED    | [issue-003.md](issue-003.md) |
+| #4    | gRPC-Web client service layer                          | COMPLETED    | [issue-004.md](issue-004.md) |
diff --git a/implementation-plans/issue-004.md b/implementation-plans/issue-004.md
new file mode 100644
index 0000000..fc91eb9
--- /dev/null
+++ b/implementation-plans/issue-004.md
@@ -0,0 +1,25 @@
+---
+---
+
+# Issue #4: gRPC-Web client service layer
+
+**Status:** COMPLETED
+**Issue:** https://git.shahondin1624.de/llm-multiverse/llm-multiverse-ui/issues/4
+**Branch:** `feature/issue-4-grpc-web-client`
+
+## Summary
+
+Create `src/lib/services/orchestrator.ts` wrapping Connect-Web client for the OrchestratorService, with typed `processRequest()` async generator and error mapping.
+
+## Acceptance Criteria
+
+- [x] `src/lib/services/orchestrator.ts` module created
+- [x] Wraps generated gRPC-Web stubs with typed interface
+- [x] Connection setup with configurable endpoint
+- [x] Error mapping from gRPC status codes to application errors
+- [x] `processRequest()` returns an async iterator of `ProcessRequestResponse`
+- [x] Handles streaming responses correctly
+
+## Deviations
+
+None.
diff --git a/src/lib/services/.gitkeep b/src/lib/services/.gitkeep
deleted file mode 100644
index e69de29..0000000
diff --git a/src/lib/services/orchestrator.ts b/src/lib/services/orchestrator.ts
new file mode 100644
index 0000000..1fe6d52
--- /dev/null
+++ b/src/lib/services/orchestrator.ts
@@ -0,0 +1,89 @@
+import { createClient } from '@connectrpc/connect';
+import { createGrpcWebTransport } from '@connectrpc/connect-web';
+import { OrchestratorService } from '$lib/proto/llm_multiverse/v1/orchestrator_pb';
+import type {
+	ProcessRequestResponse,
+	SessionConfig
+} from '$lib/proto/llm_multiverse/v1/orchestrator_pb';
+import { create } from '@bufbuild/protobuf';
+import { ProcessRequestRequestSchema } from '$lib/proto/llm_multiverse/v1/orchestrator_pb';
+
+/**
+ * Application-level error wrapping gRPC status codes.
+ */
+export class OrchestratorError extends Error {
+	constructor(
+		message: string,
+		public readonly code: string,
+		public readonly details?: string
+	) {
+		super(message);
+		this.name = 'OrchestratorError';
+	}
+}
+
+const DEFAULT_ENDPOINT = '/';
+
+let transport: ReturnType<typeof createGrpcWebTransport> | null = null;
+
+function getTransport(endpoint?: string) {
+	if (!transport) {
+		transport = createGrpcWebTransport({
+			baseUrl: endpoint ?? DEFAULT_ENDPOINT
+		});
+	}
+	return transport;
+}
+
+/**
+ * Reset the transport (useful for reconfiguring the endpoint).
+ */
+export function resetTransport(): void {
+	transport = null;
+}
+
+/**
+ * Create a configured orchestrator client.
+ */
+function getClient(endpoint?: string) {
+	return createClient(OrchestratorService, getTransport(endpoint));
+}
+
+/**
+ * Send a request to the orchestrator and yield streaming responses.
+ *
+ * Returns an async iterator of `ProcessRequestResponse` messages,
+ * each containing the current orchestration state, status message,
+ * and optionally intermediate or final results.
+ */
+export async function* processRequest(
+	sessionId: string,
+	userMessage: string,
+	sessionConfig?: SessionConfig,
+	endpoint?: string
+): AsyncGenerator<ProcessRequestResponse> {
+	const client = getClient(endpoint);
+
+	const request = create(ProcessRequestRequestSchema, {
+		sessionId,
+		userMessage,
+		sessionConfig
+	});
+
+	try {
+		for await (const response of client.processRequest(request)) {
+			yield response;
+		}
+	} catch (err: unknown) {
+		if (err instanceof Error) {
+			// ConnectError has a `code` property
+			const code = 'code' in err ? (err as { code: unknown }).code : undefined;
+			throw new OrchestratorError(
+				err.message,
+				typeof code === 'string' ? code : 'unknown',
+				err.message
+			);
+		}
+		throw new OrchestratorError('Unknown error', 'unknown');
+	}
+}
-- 
2.49.1