fix(core): run Figma OAuth setup as plugin

.opencode/opencode.jsonc

@@ -12,7 +12,12 @@
       "description": "Contains opencode logs and data",
     },
   },
-  "mcp": {},
+  "mcp": {
+    "figma": {
+      "type": "remote",
+      "url": "https://mcp.figma.com/mcp",
+    },
+  },
   "tools": {
     "github-triage": false,
     "github-pr-search": false,

packages/core/src/plugin/figma.ts

@@ -0,0 +1,37 @@
+export * as FigmaPlugin from "./figma"
+
+import { define } from "@opencode-ai/plugin/v2/effect/plugin"
+import { Effect } from "effect"
+import { Config } from "../config"
+import { ConfigMCP } from "../config/mcp"
+import { MCP } from "../mcp/index"
+
+const CLIENT_ID = "3zVHNs9kINDDrk8loekLZV"
+
+export function apply(server: typeof ConfigMCP.Server.Type) {
+  if (server.type !== "remote" || server.oauth === false) return server
+  if (!URL.canParse(server.url) || new URL(server.url).hostname !== "mcp.figma.com") return server
+  if (server.oauth?.client_id) return server
+  if (server.oauth) {
+    Object.assign(server.oauth, { client_id: CLIENT_ID })
+    return server
+  }
+  Object.assign(server, { oauth: { client_id: CLIENT_ID } })
+  return server
+}
+
+export const Plugin = define({
+  id: "opencode.figma",
+  effect: Effect.fn(function* () {
+    const config = yield* Config.Service
+    const mcp = yield* MCP.Service
+    const documents = (yield* config.entries()).filter((entry): entry is Config.Document => entry.type === "document")
+    for (const entry of documents) {
+      for (const [name, server] of Object.entries(entry.info.mcp?.servers ?? {})) {
+        if (server.type !== "remote" || !URL.canParse(server.url) || new URL(server.url).hostname !== "mcp.figma.com")
+          continue
+        yield* mcp.add(name, apply(server))
+      }
+    }
+  }),
+})

packages/core/src/plugin/internal.ts

@@ -24,6 +24,7 @@ import { Integration } from "../integration"
 import { Location } from "../location"
 import { LocationMutation } from "../location-mutation"
 import { ModelsDev } from "../models-dev"
+import { MCP } from "../mcp/index"
 import { Npm } from "@opencode-ai/util/npm"
 import { PermissionV2 } from "../permission"
 import { Reference } from "../reference"
@@ -48,6 +49,7 @@ import { WellKnown } from "../wellknown"
 import { WriteTool } from "../tool/write"
 import { AgentPlugin } from "./agent"
 import { CommandPlugin } from "./command"
+import { FigmaPlugin } from "./figma"
 import { ModelsDevPlugin } from "./models-dev"
 import { ProviderPlugins } from "./provider"
 import { PluginRuntime } from "./runtime"
@@ -73,6 +75,7 @@ const services = Effect.fn("PluginInternal.services")(function* () {
   const location = yield* Location.Service
   const locationMutation = yield* LocationMutation.Service
   const models = yield* ModelsDev.Service
+  const mcp = yield* MCP.Service
   const npm = yield* Npm.Service
   const permission = yield* PermissionV2.Service
   const runtime = yield* PluginRuntime.Service
@@ -102,6 +105,7 @@ const services = Effect.fn("PluginInternal.services")(function* () {
     Context.make(Location.Service, location),
     Context.make(LocationMutation.Service, locationMutation),
     Context.make(ModelsDev.Service, models),
+    Context.make(MCP.Service, mcp),
     Context.make(Npm.Service, npm),
     Context.make(PermissionV2.Service, permission),
     Context.make(PluginRuntime.Service, runtime),
@@ -126,6 +130,7 @@ export type InternalPlugin = Plugin<Requirements | Scope.Scope>
 
 const pre = [
   WellKnownPlugin.Plugin,
+  FigmaPlugin.Plugin,
   AgentPlugin.Plugin,
   CommandPlugin.Plugin,
   SkillPlugin.Plugin,

packages/core/src/plugin/supervisor.ts

@@ -23,6 +23,7 @@ import { Integration } from "../integration"
 import { Location } from "../location"
 import { LocationMutation } from "../location-mutation"
 import { ModelsDev } from "../models-dev"
+import { MCP } from "../mcp/index"
 import { Npm } from "@opencode-ai/util/npm"
 import { PermissionV2 } from "../permission"
 import { PluginV2 } from "../plugin"
@@ -292,6 +293,7 @@ export const node = makeLocationNode({
     Location.node,
     LocationMutation.node,
     ModelsDev.node,
+    MCP.node,
     Npm.node,
     PermissionV2.node,
     PluginRuntime.node,

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()
+  })
+})