refactor: extract shared Adapter type (claude|codex)

Introduces packages/shared/src/adapter.ts as the single source of truth
for the "claude" | "codex" runtime-adapter union, previously duplicated
(often under different local names: AgentAdapter, AdapterType,
RuntimeAdapter, PreviewAdapter, CloudRuntimeAdapter) across core, ui,
workspace-server, agent, api-client, and the desktop/mobile apps.

All call sites now import Adapter from @posthog/shared instead of
redeclaring the literal union.

Author: jonathanlab

apps/code/src/renderer/desktop-services.ts

@@ -49,7 +49,11 @@ import {
   NOTIFICATIONS_SERVICE,
   type NotificationTarget,
 } from "@posthog/platform/notifications";
-import { AUTORESEARCH_FLAG, type CloudRegion } from "@posthog/shared";
+import {
+  type Adapter,
+  AUTORESEARCH_FLAG,
+  type CloudRegion,
+} from "@posthog/shared";
 import {
   AUTH_SIDE_EFFECTS,
   type IAuthSideEffects,
@@ -116,7 +120,7 @@ const reportModelResolverLog = logger.scope("report-model-resolver");
 container.bind<ReportModelResolver>(REPORT_MODEL_RESOLVER).toConstantValue({
   async resolveDefaultModel(
     apiHost: string,
-    adapter: "claude" | "codex",
+    adapter: Adapter,
     preferredModel?: string | null,
   ): Promise<string | undefined> {
     try {

apps/mobile/src/features/tasks/api.ts

@@ -1,3 +1,4 @@
+import type { Adapter } from "@posthog/shared";
 import { fetch } from "expo/fetch";
 import {
   authedFetch,
@@ -421,7 +422,7 @@ export interface RunTaskInCloudOptions {
   pendingUserMessage?: string;
   mode?: "interactive" | "background";
   /** Adapter to use on the cloud runner. Currently only "claude" on mobile. */
-  runtimeAdapter?: "claude" | "codex";
+  runtimeAdapter?: Adapter;
   /** Gateway model ID, e.g. "claude-opus-4-8". */
   model?: string;
   /** Reasoning effort: "low" | "medium" | "high" (model-dependent). */

packages/agent/e2e/config.ts

@@ -1,7 +1,8 @@
 import { existsSync } from "node:fs";
 import { join } from "node:path";
+import type { Adapter } from "@posthog/shared";
 
-export type Adapter = "claude" | "codex";
+export type { Adapter };
 
 /**
  * Live e2e configuration, resolved entirely from the environment so no secret is

packages/agent/src/adapters/acp-connection.ts

@@ -1,4 +1,5 @@
 import { AgentSideConnection, ndJsonStream } from "@agentclientprotocol/sdk";
+import type { Adapter } from "@posthog/shared";
 import type { SessionLogWriter } from "../session-log-writer";
 import type { PostHogAPIConfig, ProcessSpawnedCallback } from "../types";
 import { Logger } from "../utils/logger";
@@ -13,10 +14,8 @@ import { nativeCodexBinaryPath } from "./codex-app-server/binary-path";
 import { CodexAppServerAgent } from "./codex-app-server/codex-app-server-agent";
 import type { CodexOptions } from "./codex-app-server/spawn";
 
-type AgentAdapter = "claude" | "codex";
-
 export type AcpConnectionConfig = {
-  adapter?: AgentAdapter;
+  adapter?: Adapter;
   logWriter?: SessionLogWriter;
   taskRunId?: string;
   taskId?: string;

packages/agent/src/adapters/reasoning-effort.ts

@@ -1,8 +1,7 @@
+import type { Adapter } from "@posthog/shared";
 import { getEffortOptions as getClaudeEffortOptions } from "./claude/session/models";
 import { getReasoningEffortOptions as getCodexReasoningEffortOptions } from "./codex-app-server/models";
 
-export type RuntimeAdapter = "claude" | "codex";
-
 export type SupportedReasoningEffort =
   | "low"
   | "medium"
@@ -16,7 +15,7 @@ export interface ReasoningEffortOption {
 }
 
 export function getReasoningEffortOptions(
-  adapter: RuntimeAdapter,
+  adapter: Adapter,
   modelId: string,
 ): ReasoningEffortOption[] | null {
   const options =
@@ -28,7 +27,7 @@ export function getReasoningEffortOptions(
 }
 
 export function isSupportedReasoningEffort(
-  adapter: RuntimeAdapter,
+  adapter: Adapter,
   modelId: string,
   value: string,
 ): value is SupportedReasoningEffort {

packages/agent/src/server/agent-server.test.ts

@@ -3,6 +3,7 @@ import { mkdir, mkdtemp, readFile, rm, writeFile } from "node:fs/promises";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
 import type { ContentBlock } from "@agentclientprotocol/sdk";
+import type { Adapter } from "@posthog/shared";
 import { zipSync } from "fflate";
 import jwt from "jsonwebtoken";
 import { type SetupServerApi, setupServer } from "msw/node";
@@ -228,9 +229,9 @@ interface TestableServer {
     inboxReportUrl?: string | null,
   ): string | { append: string };
   buildCodexInstructions(systemPrompt: string | { append: string }): string;
-  getRuntimeAdapter(): "claude" | "codex";
+  getRuntimeAdapter(): Adapter;
   buildClaudeCodeSessionMeta(
-    runtimeAdapter: "claude" | "codex",
+    runtimeAdapter: Adapter,
   ): { claudeCode: { options: Record<string, unknown> } } | undefined;
 }
 
@@ -240,7 +241,7 @@ interface NativeResumeTestServer {
     payload: JwtPayload,
     posthogAPI: PostHogAPIClient,
     preTaskRun: TaskRun | null,
-    runtimeAdapter: "claude" | "codex",
+    runtimeAdapter: Adapter,
     cwd: string,
     permissionMode: PermissionMode,
   ): Promise<{ sessionId: string; warm: boolean } | null>;

packages/agent/src/server/agent-server.ts

@@ -16,6 +16,7 @@ import {
 import { type ServerType, serve } from "@hono/node-server";
 import { execGh } from "@posthog/git/gh";
 import { getCurrentBranch } from "@posthog/git/queries";
+import type { Adapter } from "@posthog/shared";
 import { unzipSync } from "fflate";
 import { Hono } from "hono";
 import { z } from "zod";
@@ -396,7 +397,7 @@ export class AgentServer {
     this.app = this.createApp();
   }
 
-  private getRuntimeAdapter(): "claude" | "codex" {
+  private getRuntimeAdapter(): Adapter {
     return this.config.runtimeAdapter ?? "claude";
   }
 
@@ -669,7 +670,7 @@ export class AgentServer {
     payload: JwtPayload,
     posthogAPI: PostHogAPIClient,
     preTaskRun: TaskRun | null,
-    runtimeAdapter: "claude" | "codex",
+    runtimeAdapter: Adapter,
     cwd: string,
     permissionMode: PermissionMode,
   ): Promise<{ sessionId: string; warm: boolean } | null> {
@@ -2543,7 +2544,7 @@ export class AgentServer {
    * it cannot sit behind a plugins guard.
    */
   private buildClaudeCodeSessionMeta(
-    runtimeAdapter: "claude" | "codex",
+    runtimeAdapter: Adapter,
   ): { claudeCode: { options: Record<string, unknown> } } | undefined {
     const plugins = this.config.claudeCode?.plugins;
     const effort =

packages/agent/src/server/types.ts

@@ -1,3 +1,4 @@
+import type { Adapter } from "@posthog/shared";
 import type { AgentMode } from "../types";
 import type { RemoteMcpServer } from "./schemas";
 
@@ -30,7 +31,7 @@ export interface AgentServerConfig {
   baseBranch?: string;
   claudeCode?: ClaudeCodeConfig;
   allowedDomains?: string[];
-  runtimeAdapter?: "claude" | "codex";
+  runtimeAdapter?: Adapter;
   model?: string;
   reasoningEffort?: "low" | "medium" | "high" | "xhigh" | "max";
 }

packages/agent/src/types.ts

@@ -1,4 +1,5 @@
 import type {
+  Adapter,
   GitHandoffCheckpoint,
   HandoffLocalGitState as GitHandoffLocalGitState,
   PostHogAPIConfig,
@@ -49,7 +50,7 @@ export interface ProcessSpawnedCallback {
 
 export interface TaskExecutionOptions {
   repositoryPath?: string;
-  adapter?: "claude" | "codex";
+  adapter?: Adapter;
   model?: string;
   gatewayUrl?: string;
   codexBinaryPath?: string;

packages/api-client/src/posthog-client.ts

@@ -2,6 +2,7 @@ import "./generated.augment";
 import { isSupportedReasoningEffort } from "@posthog/agent/adapters/reasoning-effort";
 import type { PermissionMode } from "@posthog/agent/execution-mode";
 import type {
+  Adapter,
   CloudRunSource,
   PrAuthorshipMode,
   SeatData,
@@ -470,10 +471,8 @@ export interface FinalizedTaskArtifactUpload {
   uploaded_at?: string;
 }
 
-type CloudRuntimeAdapter = "claude" | "codex";
-
 interface CloudRunOptions {
-  adapter?: CloudRuntimeAdapter;
+  adapter?: Adapter;
   model?: string;
   reasoningLevel?: string;
   sandboxEnvironmentId?: string;