Add Github Copilot Provider

apps/server/package.json

@@ -29,6 +29,7 @@
     "@effect/platform-bun": "catalog:",
     "@effect/platform-node": "catalog:",
     "@effect/sql-sqlite-bun": "catalog:",
+    "@github/copilot-sdk": "^0.2.2",
     "@opencode-ai/sdk": "^1.3.15",
     "@pierre/diffs": "^1.1.0-beta.16",
     "effect": "catalog:",

apps/server/src/git/Layers/CopilotTextGeneration.test.ts

@@ -0,0 +1,138 @@
+import * as NodeServices from "@effect/platform-node/NodeServices";
+import { it } from "@effect/vitest";
+import { Effect, Layer } from "effect";
+import { beforeEach, expect, vi } from "vitest";
+
+import { ServerConfig } from "../../config.ts";
+import { ServerSettingsService } from "../../serverSettings.ts";
+import { TextGeneration } from "../Services/TextGeneration.ts";
+import { CopilotTextGenerationLive } from "./CopilotTextGeneration.ts";
+
+const runtimeMock = vi.hoisted(() => {
+  const state = {
+    createdClients: [] as Array<{
+      readonly input: { readonly cwd?: string };
+      readonly client: {
+        readonly start: ReturnType<typeof vi.fn>;
+        readonly stop: ReturnType<typeof vi.fn>;
+        readonly createSession: ReturnType<typeof vi.fn>;
+      };
+    }>,
+    sessions: [] as Array<{
+      readonly disconnect: ReturnType<typeof vi.fn>;
+      readonly sendAndWait: ReturnType<typeof vi.fn>;
+    }>,
+  };
+
+  return {
+    state,
+    reset() {
+      state.createdClients = [];
+      state.sessions = [];
+    },
+  };
+});
+
+vi.mock("../../provider/copilotRuntime.ts", async () => {
+  const actual = await vi.importActual<typeof import("../../provider/copilotRuntime.ts")>(
+    "../../provider/copilotRuntime.ts",
+  );
+
+  return {
+    ...actual,
+    createCopilotClient: vi.fn((input: { readonly cwd?: string }) => {
+      const start = vi.fn(async () => undefined);
+      const stop = vi.fn(async () => undefined);
+      const createSession = vi.fn(async () => {
+        const sendAndWait = vi.fn(async () => ({
+          data: {
+            content: JSON.stringify({
+              subject: "Add change",
+              body: "",
+            }),
+          },
+        }));
+        const disconnect = vi.fn(async () => undefined);
+        runtimeMock.state.sessions.push({ disconnect, sendAndWait });
+        return {
+          sendAndWait,
+          disconnect,
+        };
+      });
+
+      const client = {
+        start,
+        stop,
+        createSession,
+      };
+      runtimeMock.state.createdClients.push({ input, client });
+      return client;
+    }),
+  };
+});
+
+beforeEach(() => {
+  runtimeMock.reset();
+});
+
+const CopilotTextGenerationTestLayer = CopilotTextGenerationLive.pipe(
+  Layer.provideMerge(
+    ServerSettingsService.layerTest({
+      providers: {
+        copilot: {
+          enabled: true,
+        },
+      },
+    }),
+  ),
+  Layer.provideMerge(
+    ServerConfig.layerTest(process.cwd(), {
+      prefix: "t3code-copilot-text-generation-test-",
+    }),
+  ),
+  Layer.provideMerge(NodeServices.layer),
+);
+
+it.layer(CopilotTextGenerationTestLayer)("CopilotTextGenerationLive", (it) => {
+  it.effect("reuses a started Copilot client across git text generation requests", () =>
+    Effect.gen(function* () {
+      const textGeneration = yield* TextGeneration;
+      const modelSelection = {
+        provider: "copilot" as const,
+        model: "gpt-4.1",
+      };
+
+      const first = yield* textGeneration.generateCommitMessage({
+        cwd: process.cwd(),
+        branch: "feature/copilot-text-generation",
+        stagedSummary: "M README.md",
+        stagedPatch: "diff --git a/README.md b/README.md",
+        modelSelection,
+      });
+
+      const second = yield* textGeneration.generateCommitMessage({
+        cwd: process.cwd(),
+        branch: "feature/copilot-text-generation",
+        stagedSummary: "M README.md",
+        stagedPatch: "diff --git a/README.md b/README.md",
+        modelSelection,
+      });
+
+      expect(first.subject).toBe("Add change");
+      expect(second.subject).toBe("Add change");
+
+      expect(runtimeMock.state.createdClients).toHaveLength(1);
+      expect(runtimeMock.state.sessions).toHaveLength(2);
+
+      const sharedClient = runtimeMock.state.createdClients[0]?.client;
+      expect(sharedClient?.start).toHaveBeenCalledTimes(1);
+      expect(sharedClient?.createSession).toHaveBeenCalledTimes(2);
+      expect(sharedClient?.stop).not.toHaveBeenCalled();
+
+      expect(runtimeMock.state.sessions[0]?.sendAndWait).toHaveBeenCalledTimes(1);
+      expect(runtimeMock.state.sessions[0]?.disconnect).toHaveBeenCalledTimes(1);
+      expect(runtimeMock.state.sessions[1]?.sendAndWait).toHaveBeenCalledTimes(1);
+      expect(runtimeMock.state.sessions[1]?.disconnect).toHaveBeenCalledTimes(1);
+    }),
+  );
+});