fix(core): apply Figma OAuth config before startup

packages/core/test/plugin/figma.test.ts

@@ -0,0 +1,47 @@
+import { describe, expect, test } from "bun:test"
+import { ConfigMCP } from "@opencode-ai/core/config/mcp"
+import { FigmaPlugin } from "@opencode-ai/core/plugin/figma"
+
+describe("plugin.figma", () => {
+  test("adds the OpenCode client ID to configured Figma servers", () => {
+    const server = new ConfigMCP.Remote({
+      type: "remote",
+      url: "https://mcp.figma.com/mcp",
+      oauth: new ConfigMCP.OAuth({ scope: "mcp:connect" }),
+    })
+
+    FigmaPlugin.apply(server)
+
+    expect(server.oauth).toEqual({ client_id: "3zVHNs9kINDDrk8loekLZV", scope: "mcp:connect" })
+  })
+
+  test("preserves an existing client ID", () => {
+    const server = new ConfigMCP.Remote({
+      type: "remote",
+      url: "https://mcp.figma.com/mcp",
+      oauth: new ConfigMCP.OAuth({ client_id: "configured-client-id" }),
+    })
+
+    FigmaPlugin.apply(server)
+
+    expect(server.oauth).toEqual({ client_id: "configured-client-id" })
+  })
+
+  test("does not enable OAuth or modify non-Figma servers", () => {
+    const disabled = new ConfigMCP.Remote({
+      type: "remote",
+      url: "https://mcp.figma.com/mcp",
+      oauth: false,
+    })
+    const other = new ConfigMCP.Remote({
+      type: "remote",
+      url: "https://mcp.example.com/mcp",
+    })
+
+    FigmaPlugin.apply(disabled)
+    FigmaPlugin.apply(other)
+
+    expect(disabled.oauth).toBe(false)
+    expect(other.oauth).toBeUndefined()
+  })
+})