refactor(codex): split the Codex harness into runtime and UI

src/bundled/codex/index.test.ts

@@ -1,11 +1,11 @@
 // @vitest-environment jsdom
 import { afterEach, beforeEach, expect, it, vi } from "vitest";
-import type { AgentType } from "../../features/agents/service";
 import { CodexLogoIcon } from "../../shared/design-system/icons";
 import { CodexRuntime } from "./runtime";
 import { CodexSetup } from "./setup";
 import { CodexProvider } from "./tabs";
-import { apply } from "./index";
+import * as codex from "./index";
+import { appliedType } from "../../features/agents/plugin-testing";
 
 const desktop = vi.hoisted(() => ({ tauri: true }));
 vi.mock("@tauri-apps/api/core", () => ({ isTauri: () => desktop.tauri }));
@@ -21,23 +21,18 @@ afterEach(() => {
 
 /** Applies the plugin to a stand-in context and returns the registered type. */
 function applied() {
-  let type: AgentType | undefined;
   const subscribe = () => () => undefined;
   const ctx = {
     pluginOwner: { id: "buzz.codex", revision: "r1" },
     host: { spawn: vi.fn(), request: vi.fn() },
     agents: {
-      register: (registered: AgentType) => {
-        type = registered;
-      },
       snapshot: () => ({ status: "ready", agents: [], running: [] }),
       relay: () => undefined,
       subscribe,
     },
     effect: vi.fn(),
   };
-  apply(ctx as never);
-  return type;
+  return appliedType(codex, ctx);
 }
 
 it("registers only where the desktop app can run codex and base64", () => {
@@ -123,7 +118,7 @@ it("stops agents that stop running even when the agent list could not be read",
   const agent = { pubkey: "agent", type: "buzz.codex/codex" };
   let state = { status: "ready", agents: [agent], running: [agent] };
   let notify = () => undefined;
-  apply({
+  codex.agent.apply({
     pluginOwner: { id: "buzz.codex" },
     host: { spawn: vi.fn(), request: vi.fn() },
     agents: {
@@ -187,7 +182,7 @@ it("starts the server once Codex is updated and checked, only while a Codex agen
     notify();
   };
   let cleanup: () => void = () => undefined;
-  apply({
+  codex.agent.apply({
     pluginOwner: { id: "buzz.codex" },
     host: { spawn: vi.fn(), request: vi.fn() },
     agents: {

src/bundled/codex/index.ts

@@ -8,15 +8,68 @@ import { type Config, config, defaults, validWorkspace } from "./config";
 import { codexRun, TYPE_ID } from "./run";
 import { CodexRuntime } from "./runtime";
 import { CodexSetup, withScript } from "./setup";
-import { CodexProvider, createTabs } from "./tabs";
+import { CodexProvider, createTabs, transcripts } from "./tabs";
 import { readUsage } from "./usage";
 /** How often Buzz's copy of Codex looks for a new release. */
 const UPDATE_MS = 6 * 60 * 60_000;
-export const inject = ["agents", "host"];
+// Only the desktop app can start `codex`, and setup and file uploads run
+// `bash` and `base64`, which stock Windows lacks; no unusable type elsewhere.
+const supported = () => isTauri() && /Mac|Linux/i.test(navigator.platform);
+
+/** What the type's UI reaches of its runtime. */
+type CodexExposed = Readonly<{
+  provider: Parameters<typeof createTabs>[0];
+  runtime: Parameters<typeof createTabs>[1];
+  transcript: Parameters<typeof createTabs>[2];
+  setup: Parameters<typeof createTabs>[3];
+}>;
+
+export const inject = ["agents"];
 export const apply: PluginModule["apply"] = (ctx) => {
-  // Only the desktop app can start `codex`, and setup and file uploads run
-  // `bash` and `base64`, which stock Windows lacks; no unusable type elsewhere.
-  if (!isTauri() || !/Mac|Linux/i.test(navigator.platform)) return;
+  if (!supported()) return;
+  ctx.agents.present<CodexExposed, Config>(
+    TYPE_ID,
+    ({ provider, runtime, transcript, setup }) => {
+      const {
+        Create,
+        CreateModel,
+        DefaultControl,
+        ProviderDialogBody,
+        SettingsTab,
+        ActivityTab,
+      } = createTabs(provider, runtime, transcript, setup);
+      return {
+        icon: CodexLogoIcon,
+        Create,
+        CreateModel,
+        provider: { DialogBody: ProviderDialogBody, DefaultControl },
+        tabs: [
+          {
+            id: "settings",
+            title: "Settings",
+            role: "settings",
+            splitSettings: true,
+            component: SettingsTab,
+          },
+          {
+            id: "activity",
+            title: "Activity",
+            role: "activity",
+            component: ActivityTab,
+          },
+        ],
+      };
+    },
+  );
+};
+
+// The runtime, which runs where the agents do.
+export const agent: NonNullable<PluginModule["agent"]> = {
+  inject: ["agents", "host"],
+  apply: (ctx) => applyAgent(ctx),
+};
+function applyAgent(ctx: Parameters<PluginModule["apply"]>[0]) {
+  if (!supported()) return;
   const spawn = ctx.host.spawn && withScript(ctx.host.spawn.bind(ctx.host));
   const readFile = ctx.host.readFile?.bind(ctx.host);
   const setup = new CodexSetup(spawn, (input) => ctx.host.request(input));
@@ -89,23 +142,18 @@ export const apply: PluginModule["apply"] = (ctx) => {
     runtime.dispose();
     setup.dispose();
   });
-  const {
-    Create,
-    CreateModel,
-    DefaultControl,
-    ProviderDialogBody,
-    SettingsTab,
-    ActivityTab,
-  } = createTabs(providerController, runtime, start, setup);
   ctx.agents.register<Config>({
     id: TYPE_ID,
     title: "Codex",
-    icon: CodexLogoIcon,
     description:
       "Codex on this computer, using its native coding tools and your account.",
     defaults: () => ({ config: { ...defaults } }),
-    Create,
-    CreateModel,
+    expose: {
+      provider: providerController,
+      runtime,
+      transcript: transcripts(start, runtime),
+      setup,
+    } satisfies CodexExposed,
     importShared: (source) =>
       source.runtime === "codex" &&
       (!source.provider || source.provider === "openai")
@@ -155,8 +203,6 @@ export const apply: PluginModule["apply"] = (ctx) => {
       snapshot: providerController.snapshot,
       subscribe: providerController.subscribe,
       check: () => providerController.check(),
-      DialogBody: ProviderDialogBody,
-      DefaultControl,
     },
     sessions: {
       list: (key) => {
@@ -177,26 +223,11 @@ export const apply: PluginModule["apply"] = (ctx) => {
       },
       subscribe: runtime.subscribe,
     },
-    tabs: [
-      {
-        id: "settings",
-        title: "Settings",
-        role: "settings",
-        splitSettings: true,
-        component: SettingsTab,
-      },
-      {
-        id: "activity",
-        title: "Activity",
-        role: "activity",
-        component: ActivityTab,
-      },
-    ],
     // A mention during the first download waits for it, within its deadline.
     ...codexRun(runtime, async (signal) => {
       await setup.installed(signal);
       if (providerController.snapshot().readiness === "checking")
         await providerController.check();
     }),
   });
-};
+}

src/bundled/codex/runtime.test.ts

@@ -1,7 +1,7 @@
 import { createHash } from "node:crypto";
 import { schnorr } from "@noble/curves/secp256k1.js";
 import { bytesToHex } from "nostr-tools/utils";
-import { apply } from "./index";
+import { agent as codexAgent } from "./index";
 import { describe, afterEach, expect, it, vi } from "vitest";
 import { pubkeyOf } from "../../features/agents/membership";
 import { ownerReads } from "../../features/agents/reads";
@@ -436,7 +436,7 @@ function fixture(
   if (plugin) {
     vi.stubGlobal("localStorage", local);
     vi.stubGlobal("navigator", { platform: "MacIntel" });
-    apply({
+    codexAgent.apply({
       host: { spawn },
       agents: {
         snapshot: () => ({ status: "ready", agents: [], running }),
@@ -454,7 +454,7 @@ function fixture(
       effect: (effect: () => () => void) => {
         pluginDispose = effect();
       },
-    } as unknown as Parameters<typeof apply>[0]);
+    } as unknown as Parameters<typeof codexAgent.apply>[0]);
   }
   const starts = () => sent.filter((wire) => wire.method === "turn/start");
   const interrupt = () => {

src/bundled/codex/tabs.test.tsx

@@ -30,7 +30,7 @@ import type { RelayData } from "../../features/relay/service";
 import { PanelWorkspace } from "../../features/panels/PanelWorkspace";
 import { defaults, type Config } from "./config";
 import { sessionTag } from "./prompt";
-import { CodexProvider, createTabs } from "./tabs";
+import { CodexProvider, createTabs, transcripts } from "./tabs";
 import { CodexRuntime } from "./runtime";
 import type { Wire } from "./rpc";
 import { CodexSetup } from "./setup";
@@ -200,7 +200,12 @@ function fixture({
     sessions,
     (raw) => provider.resolve(raw),
   );
-  const tabs = createTabs(provider, runtime, spawn, setup);
+  const tabs = createTabs(
+    provider,
+    runtime,
+    transcripts(spawn, runtime),
+    setup,
+  );
   const props = (settings = defaults, save = vi.fn(async () => {})) =>
     ({
       agent: {
@@ -1291,7 +1296,7 @@ it("installs and signs in Buzz's copy of Codex from its provider settings", asyn
   const { ProviderDialogBody } = createTabs(
     provider,
     f.runtime,
-    f.spawn,
+    transcripts(f.spawn, f.runtime),
     f.setup,
   );
   render(<ProviderDialogBody onClose={vi.fn()} />);

src/bundled/codex/tabs.tsx

@@ -52,7 +52,12 @@ import {
 import { AppServer, listModels, needsSignIn, type Spawn } from "./rpc";
 import type { CodexRuntime, SavedConversation } from "./runtime";
 import type { CodexSetup } from "./setup";
-import { readTranscript, TURN_LIMIT, type CodexTranscript } from "./transcript";
+import {
+  readTranscript,
+  TURN_LIMIT,
+  type CodexTranscript,
+  type Lookup,
+} from "./transcript";
 
 const label = ({ channelId, name, root }: SavedConversation) =>
   `${name ? `#${name}` : channelId.slice(0, 8)} · ${root ? `thread ${root.slice(0, 8)}` : "channel"}`;
@@ -310,7 +315,7 @@ function CodexSignIn({
   check,
   disabled,
 }: {
-  login: CodexSetup;
+  login: SetupHandle;
   step: "install" | "login";
   checking: boolean;
   check(): void;
@@ -412,11 +417,39 @@ function CodexSignIn({
   );
 }
 
+// What the tabs reach of the runtime: stores and calls returning promises,
+// as an agent type's `expose` allows.
+type ProviderHandle = Pick<
+  CodexProvider,
+  "snapshot" | "subscribe" | "check" | "resolve" | "saveDefaults"
+>;
+type ActivityHandle = Pick<
+  CodexRuntime,
+  "subscribe" | "sessions" | "conversations" | "find"
+>;
+type SetupHandle = Pick<
+  CodexSetup,
+  "snapshot" | "subscribe" | "run" | "cancel"
+>;
+/** Reads one conversation's Codex thread. */
+export type TranscriptRead = (
+  agent: Lookup["agent"],
+  conversation: SavedConversation,
+  signal: AbortSignal,
+) => Promise<CodexTranscript | undefined>;
+/** Transcripts read with `spawn`, named by the runtime. */
+export const transcripts =
+  (spawn: Spawn, runtime: Pick<CodexRuntime, "name">): TranscriptRead =>
+  (agent, conversation, signal) =>
+    readTranscript(spawn, { agent, ...conversation }, signal, (pubkey) =>
+      runtime.name(agent.key, pubkey),
+    );
+
 export function createTabs(
-  provider: CodexProvider,
-  runtime: CodexRuntime,
-  spawn: Spawn,
-  setup: CodexSetup,
+  provider: ProviderHandle,
+  runtime: ActivityHandle,
+  transcript: TranscriptRead,
+  setup: SetupHandle,
 ) {
   const login = setup;
 
@@ -738,11 +771,10 @@ export function createTabs(
     useEffect(() => {
       const abort = new AbortController();
       setLoading(true);
-      void readTranscript(
-        spawn,
-        { agent: { key: agent.key, name: agent.name }, ...conversation },
+      void transcript(
+        { key: agent.key, name: agent.name },
+        conversation,
         abort.signal,
-        (pubkey) => runtime.name(agent.key, pubkey),
       )
         .then(
           (transcript): Read =>