diff --git a/bun.lock b/bun.lock
index 7ba4144..f99aa81 100644
--- a/bun.lock
+++ b/bun.lock
@@ -61,7 +61,8 @@
       "name": "ejclaw-codex-runner",
       "version": "1.0.0",
       "dependencies": {
-        "@openai/codex": "0.133.0",
+        "@openai/codex": "0.136.0",
+        "@openai/codex-sdk": "0.136.0",
         "ejclaw-runners-shared": "workspace:*",
       },
       "devDependencies": {
@@ -221,19 +222,21 @@
 
     "@napi-rs/wasm-runtime": ["@napi-rs/wasm-runtime@1.1.4", "", { "dependencies": { "@tybys/wasm-util": "^0.10.1" }, "peerDependencies": { "@emnapi/core": "^1.7.1", "@emnapi/runtime": "^1.7.1" } }, "sha512-3NQNNgA1YSlJb/kMH1ildASP9HW7/7kYnRI2szWJaofaS1hWmbGI4H+d3+22aGzXXN9IJ+n+GiFVcGipJP18ow=="],
 
-    "@openai/codex": ["@openai/codex@0.133.0", "", { "optionalDependencies": { "@openai/codex-darwin-arm64": "npm:@openai/codex@0.133.0-darwin-arm64", "@openai/codex-darwin-x64": "npm:@openai/codex@0.133.0-darwin-x64", "@openai/codex-linux-arm64": "npm:@openai/codex@0.133.0-linux-arm64", "@openai/codex-linux-x64": "npm:@openai/codex@0.133.0-linux-x64", "@openai/codex-win32-arm64": "npm:@openai/codex@0.133.0-win32-arm64", "@openai/codex-win32-x64": "npm:@openai/codex@0.133.0-win32-x64" }, "bin": { "codex": "bin/codex.js" } }, "sha512-Gh42kLLBo/6gpnHmDzUWDVvyS57ekCB1+1Dz0RG2oIl3Lhk1uwrjSj/PwaJWWh4Rw/rUp1RqkwrMugFfFEOlqQ=="],
+    "@openai/codex": ["@openai/codex@0.136.0", "", { "optionalDependencies": { "@openai/codex-darwin-arm64": "npm:@openai/codex@0.136.0-darwin-arm64", "@openai/codex-darwin-x64": "npm:@openai/codex@0.136.0-darwin-x64", "@openai/codex-linux-arm64": "npm:@openai/codex@0.136.0-linux-arm64", "@openai/codex-linux-x64": "npm:@openai/codex@0.136.0-linux-x64", "@openai/codex-win32-arm64": "npm:@openai/codex@0.136.0-win32-arm64", "@openai/codex-win32-x64": "npm:@openai/codex@0.136.0-win32-x64" }, "bin": { "codex": "bin/codex.js" } }, "sha512-yu+diXznSOt8h296/CDOf2CNi55z1raA7aZ6sejjGy1QWPqn72YkBc2ByTzZG6G+1yiUqlm2G5Hid54hm3/kaA=="],
 
-    "@openai/codex-darwin-arm64": ["@openai/codex@0.133.0-darwin-arm64", "", { "os": "darwin", "cpu": "arm64" }, "sha512-W7f8+DckLujnqGlptKCzgJU+ooeHKMuk6KYgMFP6A9asn7YUsGUgJqjiBaX8oNcXO6w/pTbKGRARx1kCNS8lIg=="],
+    "@openai/codex-darwin-arm64": ["@openai/codex@0.136.0-darwin-arm64", "", { "os": "darwin", "cpu": "arm64" }, "sha512-9xnEohnUO9l6qtPSDbG0Y2UXX5mBZ9Lsn0VMgjtkREGfWL9TawNC1d7D1ERMSJtHTlVvieoaFyK9LHPLQCO9Vw=="],
 
-    "@openai/codex-darwin-x64": ["@openai/codex@0.133.0-darwin-x64", "", { "os": "darwin", "cpu": "x64" }, "sha512-Ek8ikvLOiXZ8emcIJVBXxK6fm8ratBy0kaEt3JNisTNszxGshUHf/R4xxDxIyKNcUkYYXjW7A/rMwW3iu3OFlg=="],
+    "@openai/codex-darwin-x64": ["@openai/codex@0.136.0-darwin-x64", "", { "os": "darwin", "cpu": "x64" }, "sha512-HD9YLalPg0cv+CiZSmRWOl/8sefuJlxJcAmxyzb8mSaAMchD3V+2yS6M6E1Z2I6NX1irp4Polt1fPsjGdlHYhQ=="],
 
-    "@openai/codex-linux-arm64": ["@openai/codex@0.133.0-linux-arm64", "", { "os": "linux", "cpu": "arm64" }, "sha512-uKXYYSJ3mY16sp4hcG/4BMNRjva/ZS4oARiI1+7k8+NiuoAhdCGWNe5u4KJ3sMuL3tp/IXcmc6B56EFX1+WDBQ=="],
+    "@openai/codex-linux-arm64": ["@openai/codex@0.136.0-linux-arm64", "", { "os": "linux", "cpu": "arm64" }, "sha512-xDxTOk5ClEX/nzlQseqEoiubjIzVZfcWKn9nmKkHOLKknz+c7n6tbmw7eY4mwt29zTAAoFoecdRnbbsPZUHJ1g=="],
 
-    "@openai/codex-linux-x64": ["@openai/codex@0.133.0-linux-x64", "", { "os": "linux", "cpu": "x64" }, "sha512-9YfyqrfUj/UZ2+aXE4zBz47t6RXbVni95ZorGsNh857vxYK/asVpUtR2cymo9lB3JaI4mQaKFfV/t7IRItqkuA=="],
+    "@openai/codex-linux-x64": ["@openai/codex@0.136.0-linux-x64", "", { "os": "linux", "cpu": "x64" }, "sha512-Q6yZHRtUWD+27B5yAiOYyPAtM0BzW0Mm23YGaXDmfNEO5BYgHuUT80VDofUpjSyo2+ShYoZQUFVQAsNPKqd+Sw=="],
 
-    "@openai/codex-win32-arm64": ["@openai/codex@0.133.0-win32-arm64", "", { "os": "win32", "cpu": "arm64" }, "sha512-mRzND0PSGHRoLk0X41GTSoc3tFjZSF4HgDlfjU5fiQcWVi0/kLb7Ku6/tPFT/X2hOLa3YdJkbIcHC0Hc9ni80g=="],
+    "@openai/codex-sdk": ["@openai/codex-sdk@0.136.0", "", { "dependencies": { "@openai/codex": "0.136.0" } }, "sha512-qrSirrVxrpVHR1YIQQ4WSouneaQrQrRAAlQWJYRflvMCcruFXorsmIPeIbDqFXOa8A9H9FHHyc+2U4tdbEGGiQ=="],
 
-    "@openai/codex-win32-x64": ["@openai/codex@0.133.0-win32-x64", "", { "os": "win32", "cpu": "x64" }, "sha512-u3ji78DIPZCGJeELuovsAnaZH+vK9gsA4F6M1y+Uy2s80Sz7/i1S0KL81qGReYji3urSjgBpkQuNP47GXOqxrQ=="],
+    "@openai/codex-win32-arm64": ["@openai/codex@0.136.0-win32-arm64", "", { "os": "win32", "cpu": "arm64" }, "sha512-mAHZXfygQxBg1JjZ9+bAZfBXe6fg8MabJhuDYhj5z0VF++orKSFsC1lMiv6PksQN36ikQefgVjc9EOlaE4lt7g=="],
+
+    "@openai/codex-win32-x64": ["@openai/codex@0.136.0-win32-x64", "", { "os": "win32", "cpu": "x64" }, "sha512-zS6DAmvjdWeAB1CL9KTUMkwzTwfXtxHy8GAtePw2a93jIqawoG07fBxAXuyoHZ3QXQkwEgqBx1zEEh33gdIKAw=="],
 
     "@oxc-project/types": ["@oxc-project/types@0.127.0", "", {}, "sha512-aIYXQBo4lCbO4z0R3FHeucQHpF46l2LbMdxRvqvuRuW2OxdnSkcng5B8+K12spgLDj93rtN3+J2Vac/TIO+ciQ=="],
 
diff --git a/runners/codex-runner/package.json b/runners/codex-runner/package.json
index ea04ccc..4387092 100644
--- a/runners/codex-runner/package.json
+++ b/runners/codex-runner/package.json
@@ -10,7 +10,8 @@
     "start": "bun dist/index.js"
   },
   "dependencies": {
-    "@openai/codex": "0.133.0",
+    "@openai/codex": "0.136.0",
+    "@openai/codex-sdk": "0.136.0",
     "ejclaw-runners-shared": "workspace:*"
   },
   "devDependencies": {
diff --git a/runners/codex-runner/src/codex-sdk-client.ts b/runners/codex-runner/src/codex-sdk-client.ts
new file mode 100644
index 0000000..2ea1fb6
--- /dev/null
+++ b/runners/codex-runner/src/codex-sdk-client.ts
@@ -0,0 +1,301 @@
+import {
+  Codex,
+  type CodexOptions,
+  type Input,
+  type ModelReasoningEffort,
+  type ThreadEvent,
+  type ThreadOptions,
+  type Usage,
+  type UserInput,
+} from '@openai/codex-sdk';
+
+import type { AppServerInputItem } from './app-server-client.js';
+
+export interface CodexSdkThreadPort {
+  id: string | null;
+  runStreamed(
+    input: Input | unknown,
+    options?: { signal?: AbortSignal },
+  ): Promise<{ events: AsyncIterable<ThreadEvent | unknown> }>;
+}
+
+export interface CodexSdkPort {
+  startThread(options?: ThreadOptions): CodexSdkThreadPort;
+  resumeThread(id: string, options?: ThreadOptions): CodexSdkThreadPort;
+}
+
+export interface CodexSdkClientOptions {
+  codex?: CodexSdkPort;
+  env?: Record<string, string>;
+  log: (message: string) => void;
+  codexPathOverride?: string;
+  config?: CodexOptions['config'];
+}
+
+export interface CodexSdkThreadStartOptions {
+  cwd: string;
+  model?: string;
+  effort?: string;
+}
+
+export interface CodexSdkTurnOptions extends CodexSdkThreadStartOptions {
+  onProgress?: (message: string) => void;
+}
+
+export interface CodexSdkTurnState {
+  status: 'pending' | 'inProgress' | 'completed' | 'failed' | 'interrupted';
+  threadId: string | null;
+  finalAnswer: string | null;
+  latestAgentMessage: string | null;
+  errorMessage: string | null;
+  usage: Usage | null;
+}
+
+export interface CodexSdkTurnResult {
+  state: CodexSdkTurnState;
+  result: string | null;
+  threadId: string | null;
+}
+
+export function createInitialCodexSdkTurnState(): CodexSdkTurnState {
+  return {
+    status: 'pending',
+    threadId: null,
+    finalAnswer: null,
+    latestAgentMessage: null,
+    errorMessage: null,
+    usage: null,
+  };
+}
+
+function isKnownReasoningEffort(
+  effort: string | undefined,
+): effort is ModelReasoningEffort {
+  return (
+    effort === 'minimal' ||
+    effort === 'low' ||
+    effort === 'medium' ||
+    effort === 'high' ||
+    effort === 'xhigh'
+  );
+}
+
+function normalizeReasoningEffort(
+  effort: string | undefined,
+): ModelReasoningEffort | undefined {
+  if (effort === 'minimal') {
+    return 'low';
+  }
+  return isKnownReasoningEffort(effort) ? effort : undefined;
+}
+
+function buildThreadOptions(
+  options: CodexSdkThreadStartOptions,
+): ThreadOptions {
+  return {
+    approvalPolicy: 'never',
+    model: options.model,
+    modelReasoningEffort: normalizeReasoningEffort(options.effort),
+    networkAccessEnabled: true,
+    sandboxMode: 'danger-full-access',
+    workingDirectory: options.cwd,
+  };
+}
+
+export function toCodexSdkInput(input: AppServerInputItem[]): UserInput[] {
+  return input.map((item) => {
+    if (item.type === 'text') {
+      return { type: 'text', text: item.text };
+    }
+    return { type: 'local_image', path: item.path };
+  });
+}
+
+export function reduceCodexSdkTurnState(
+  state: CodexSdkTurnState,
+  event: ThreadEvent | unknown,
+): CodexSdkTurnState {
+  if (!event || typeof event !== 'object' || !('type' in event)) {
+    return state;
+  }
+
+  const typed = event as ThreadEvent;
+  if (typed.type === 'thread.started') {
+    return { ...state, threadId: typed.thread_id };
+  }
+
+  if (typed.type === 'turn.started') {
+    return { ...state, status: 'inProgress' };
+  }
+
+  if (typed.type === 'item.completed') {
+    if (typed.item.type === 'agent_message') {
+      const text = typed.item.text.trim();
+      if (!text) return state;
+      return {
+        ...state,
+        finalAnswer: text,
+        latestAgentMessage: text,
+      };
+    }
+    if (typed.item.type === 'error') {
+      return {
+        ...state,
+        errorMessage: typed.item.message,
+      };
+    }
+    return state;
+  }
+
+  if (typed.type === 'turn.completed') {
+    return {
+      ...state,
+      status: state.status === 'failed' ? 'failed' : 'completed',
+      usage: typed.usage,
+    };
+  }
+
+  if (typed.type === 'turn.failed') {
+    return {
+      ...state,
+      status: 'failed',
+      errorMessage: typed.error.message,
+    };
+  }
+
+  if (typed.type === 'error') {
+    return {
+      ...state,
+      status: 'failed',
+      errorMessage: typed.message,
+    };
+  }
+
+  return state;
+}
+
+function isAbortError(error: unknown): boolean {
+  return (
+    error instanceof Error &&
+    (error.name === 'AbortError' ||
+      error.message.toLowerCase().includes('abort'))
+  );
+}
+
+export class CodexSdkClient {
+  private readonly codex: CodexSdkPort;
+  private readonly log: (message: string) => void;
+  private readonly threads = new Map<string, CodexSdkThreadPort>();
+  private nextPendingThreadId = 1;
+
+  constructor(options: CodexSdkClientOptions) {
+    this.log = options.log;
+    this.codex =
+      options.codex ??
+      new Codex({
+        codexPathOverride: options.codexPathOverride,
+        config: options.config,
+        env: options.env,
+      });
+  }
+
+  async startOrResumeThread(
+    sessionId: string | undefined,
+    options: CodexSdkThreadStartOptions,
+  ): Promise<string> {
+    const threadOptions = buildThreadOptions(options);
+    const thread = sessionId
+      ? this.codex.resumeThread(sessionId, threadOptions)
+      : this.codex.startThread(threadOptions);
+    const handle =
+      sessionId ?? `pending-sdk-thread-${this.nextPendingThreadId++}`;
+    this.threads.set(handle, thread);
+    return handle;
+  }
+
+  async startTurn(
+    threadHandle: string,
+    input: AppServerInputItem[],
+    options: CodexSdkTurnOptions,
+  ): Promise<{
+    turnId: string;
+    steer: (nextInput: AppServerInputItem[]) => Promise<void>;
+    interrupt: () => Promise<void>;
+    wait: () => Promise<CodexSdkTurnResult>;
+  }> {
+    const thread = this.threads.get(threadHandle);
+    if (!thread) {
+      throw new Error(`Unknown Codex SDK thread handle: ${threadHandle}`);
+    }
+
+    const abortController = new AbortController();
+    const waitPromise = this.consumeTurn(
+      threadHandle,
+      thread,
+      input,
+      options,
+      abortController.signal,
+    );
+
+    return {
+      turnId: threadHandle,
+      steer: async () => {
+        throw new Error(
+          'Codex SDK runner does not support mid-turn steering; queue the message for the next turn.',
+        );
+      },
+      interrupt: async () => {
+        abortController.abort();
+      },
+      wait: async () => waitPromise,
+    };
+  }
+
+  private async consumeTurn(
+    threadHandle: string,
+    thread: CodexSdkThreadPort,
+    input: AppServerInputItem[],
+    options: CodexSdkTurnOptions,
+    signal: AbortSignal,
+  ): Promise<CodexSdkTurnResult> {
+    let state = createInitialCodexSdkTurnState();
+    try {
+      const { events } = await thread.runStreamed(toCodexSdkInput(input), {
+        signal,
+      });
+      for await (const event of events) {
+        state = reduceCodexSdkTurnState(state, event);
+        if (state.threadId && state.threadId !== threadHandle) {
+          this.threads.set(state.threadId, thread);
+          this.threads.delete(threadHandle);
+        }
+        if (
+          state.latestAgentMessage &&
+          state.latestAgentMessage !== state.finalAnswer
+        ) {
+          options.onProgress?.(state.latestAgentMessage);
+        }
+      }
+    } catch (error) {
+      if (isAbortError(error)) {
+        state = { ...state, status: 'interrupted' };
+      } else {
+        const message = error instanceof Error ? error.message : String(error);
+        this.log(`Codex SDK turn failed: ${message}`);
+        state = { ...state, status: 'failed', errorMessage: message };
+      }
+    }
+
+    const threadId = state.threadId ?? thread.id;
+    if (threadId && threadId !== threadHandle) {
+      this.threads.set(threadId, thread);
+      this.threads.delete(threadHandle);
+    }
+
+    return {
+      state: { ...state, threadId },
+      result: state.finalAnswer,
+      threadId,
+    };
+  }
+}
diff --git a/runners/codex-runner/src/index.ts b/runners/codex-runner/src/index.ts
index 0db0b5e..14b5680 100644
--- a/runners/codex-runner/src/index.ts
+++ b/runners/codex-runner/src/index.ts
@@ -1,7 +1,10 @@
 /**
  * EJClaw Codex Runner
  *
- * App-server only runtime.
+ * App-server by default, with optional CODEX_RUNTIME=sdk lane.
+ * SDK mode uses @openai/codex-sdk / codex exec JSON events and leaves
+ * mid-turn IPC follow-ups queued for the next run because SDK steering is
+ * not currently available.
  *
  * Input protocol:
  *   Stdin: Full RunnerInput JSON (read until EOF)
@@ -27,6 +30,8 @@ import {
 
 import { CodexAppServerClient } from './app-server-client.js';
 import { parseAppServerInput } from './app-server-input.js';
+import { CodexSdkClient } from './codex-sdk-client.js';
+import { resolveCodexRuntimeMode } from './runtime-mode.js';
 import {
   prependRoomRoleHeader,
   type RoomRoleContext,
@@ -104,6 +109,15 @@ function log(message: string): void {
   console.error(`[codex-runner] ${message}`);
 }
 
+function toStringEnv(env: NodeJS.ProcessEnv): Record<string, string> {
+  return Object.fromEntries(
+    Object.entries(env).filter((entry): entry is [string, string] => {
+      const [, value] = entry;
+      return typeof value === 'string';
+    }),
+  );
+}
+
 function isCodexGoalsEnabled(runnerInput: RunnerInput): boolean {
   return runnerInput.codexGoals === true || process.env.CODEX_GOALS === 'true';
 }
@@ -283,6 +297,117 @@ async function executeAppServerTurn(
   }
 }
 
+function countQueuedIpcInputFiles(): number {
+  try {
+    fs.mkdirSync(IPC_INPUT_DIR, { recursive: true });
+    return fs
+      .readdirSync(IPC_INPUT_DIR)
+      .filter((file) => file.endsWith('.json')).length;
+  } catch (err) {
+    log(
+      `IPC queued input count error: ${err instanceof Error ? err.message : String(err)}`,
+    );
+    return 0;
+  }
+}
+
+async function executeSdkTurn(
+  client: CodexSdkClient,
+  threadHandle: string,
+  prompt: string,
+  retryCount = 0,
+): Promise<{
+  result: string | null;
+  error?: string;
+  threadId: string;
+}> {
+  let lastProgressMessage: string | null = null;
+  const activeTurn = await client.startTurn(
+    threadHandle,
+    parseAppServerInput(prompt, log),
+    {
+      cwd: EFFECTIVE_CWD,
+      model: CODEX_MODEL || undefined,
+      effort: CODEX_EFFORT || undefined,
+      onProgress: (message) => {
+        const trimmed = message.trim();
+        if (!trimmed || trimmed === lastProgressMessage) {
+          return;
+        }
+        lastProgressMessage = trimmed;
+        writeOutput({
+          status: 'success',
+          phase: 'progress',
+          ...normalizeStructuredOutput(trimmed),
+          newSessionId: threadHandle,
+        });
+      },
+    },
+  );
+
+  let elapsedMs = 0;
+  let polling = true;
+  let lastQueuedInputCount = 0;
+  const pollDuringTurn = async () => {
+    if (!polling) return;
+
+    if (consumeCloseSentinel()) {
+      log('Close sentinel detected during SDK turn, interrupting');
+      polling = false;
+      try {
+        await activeTurn.interrupt();
+      } catch (err) {
+        log(
+          `Failed to interrupt active SDK turn: ${
+            err instanceof Error ? err.message : String(err)
+          }`,
+        );
+      }
+      return;
+    }
+
+    const queuedInputCount = countQueuedIpcInputFiles();
+    if (queuedInputCount > 0 && queuedInputCount !== lastQueuedInputCount) {
+      lastQueuedInputCount = queuedInputCount;
+      log(
+        `SDK runtime cannot steer active turns; leaving ${queuedInputCount} queued input file(s) for the next run`,
+      );
+    }
+
+    elapsedMs += IPC_POLL_MS;
+    if (elapsedMs > 0 && elapsedMs % 60000 === 0) {
+      log(`SDK turn in progress... (${formatProgressElapsed(elapsedMs)})`);
+    }
+    setTimeout(() => void pollDuringTurn(), IPC_POLL_MS);
+  };
+
+  setTimeout(() => void pollDuringTurn(), IPC_POLL_MS);
+
+  try {
+    const { state, result, threadId } = await activeTurn.wait();
+    const finalThreadId = threadId ?? threadHandle;
+    if (state.status === 'completed') {
+      return { result, threadId: finalThreadId };
+    }
+    if (state.status === 'interrupted' && consumeCloseSentinel()) {
+      return { result, threadId: finalThreadId };
+    }
+    if (state.status === 'interrupted' && retryCount < 1) {
+      log('Codex SDK turn interrupted, retrying once...');
+      return executeSdkTurn(client, finalThreadId, prompt, retryCount + 1);
+    }
+    return {
+      result,
+      error:
+        state.errorMessage ||
+        `Codex SDK turn finished with status ${state.status}`,
+      threadId: finalThreadId,
+    };
+  } finally {
+    polling = false;
+  }
+}
+
 async function runAppServerCompact(
   client: CodexAppServerClient,
   threadId: string | undefined,
@@ -405,6 +530,64 @@ async function runAppServerSession(
   }
 }
 
+async function runSdkSession(
+  runnerInput: RunnerInput,
+  prompt: string,
+): Promise<void> {
+  const reviewerRuntime =
+    isReviewerRuntimeEnvEnabled(process.env) ||
+    isReviewerRuntime(runnerInput.roomRoleContext);
+  const readonlyRuntime =
+    reviewerRuntime || isArbiterRuntimeEnvEnabled(process.env);
+  const clientEnv = buildReviewerGitGuardEnv(process.env, reviewerRuntime);
+  assertReadonlyWorkspaceRepoConnectivity(clientEnv, readonlyRuntime);
+  const client = new CodexSdkClient({
+    env: toStringEnv(clientEnv),
+    log,
+  });
+
+  const threadHandle = await client.startOrResumeThread(runnerInput.sessionId, {
+    cwd: EFFECTIVE_CWD,
+    model: CODEX_MODEL || undefined,
+    effort: CODEX_EFFORT || undefined,
+  });
+  log(
+    runnerInput.sessionId
+      ? `SDK thread resumed (${threadHandle})`
+      : `SDK thread started (${threadHandle})`,
+  );
+
+  log('Starting SDK turn...');
+  const { result, error, threadId } = await executeSdkTurn(
+    client,
+    threadHandle,
+    prompt,
+  );
+
+  if (error) {
+    const normalized = normalizeStructuredOutput(result || null);
+    log(`SDK turn error: ${error}`);
+    writeOutput({
+      status: 'error',
+      ...normalized,
+      newSessionId: threadId,
+      error,
+    });
+  } else {
+    const normalized = normalizeStructuredOutput(result || null);
+    writeOutput({
+      status: 'success',
+      ...normalized,
+      ...(result ? { phase: 'final' as const } : {}),
+      newSessionId: threadId,
+    });
+  }
+
+  if (consumeCloseSentinel()) {
+    log('Close sentinel detected, exiting SDK runtime');
+  }
+}
+
 // ── Main ──────────────────────────────────────────────────────────
 
 async function main(): Promise<void> {
@@ -455,8 +638,20 @@ async function main(): Promise<void> {
   }
 
   try {
-    log('Runtime selected: app-server');
-    await runAppServerSession(runnerInput, prompt);
+    const runtimeMode = resolveCodexRuntimeMode(
+      process.env,
+      {
+        codexGoals: isCodexGoalsEnabled(runnerInput),
+        roomRole: runnerInput.roomRoleContext?.role,
+      },
+      rawPrompt,
+    );
+    log(`Runtime selected: ${runtimeMode.mode} (${runtimeMode.reason})`);
+    if (runtimeMode.mode === 'sdk') {
+      await runSdkSession(runnerInput, prompt);
+    } else {
+      await runAppServerSession(runnerInput, prompt);
+    }
   } catch (err) {
     const errorMessage = err instanceof Error ? err.message : String(err);
     log(`Runner error: ${errorMessage}`);
diff --git a/runners/codex-runner/src/runtime-mode.ts b/runners/codex-runner/src/runtime-mode.ts
new file mode 100644
index 0000000..f675ed8
--- /dev/null
+++ b/runners/codex-runner/src/runtime-mode.ts
@@ -0,0 +1,85 @@
+export type CodexRuntimeMode = 'app-server' | 'sdk';
+
+export interface CodexRuntimeModeInput {
+  codexGoals?: boolean;
+  roomRole?: string;
+}
+
+export interface CodexRuntimeModeResolution {
+  mode: CodexRuntimeMode;
+  reason:
+    | 'default'
+    | 'CODEX_RUNTIME=app-server'
+    | 'CODEX_RUNTIME=sdk'
+    | 'sdk-unsupported-goals'
+    | 'sdk-unsupported-session-command'
+    | 'sdk-role-not-enabled'
+    | 'invalid-CODEX_RUNTIME';
+}
+
+function normalizeRuntimeMode(
+  raw: string | undefined,
+): CodexRuntimeMode | null {
+  if (!raw) return null;
+  const normalized = raw.trim().toLowerCase();
+  if (normalized === 'app-server' || normalized === 'appserver') {
+    return 'app-server';
+  }
+  if (normalized === 'sdk') {
+    return 'sdk';
+  }
+  return null;
+}
+
+export interface CodexRuntimeEnv {
+  [key: string]: string | undefined;
+  CODEX_RUNTIME?: string;
+  CODEX_RUNTIME_SDK_ROLES?: string;
+}
+
+function sdkRoleEnabled(
+  env: CodexRuntimeEnv,
+  roomRole: string | undefined,
+): boolean {
+  const raw = env.CODEX_RUNTIME_SDK_ROLES?.trim();
+  if (!raw) return true;
+  if (!roomRole) return false;
+  const allowed = raw
+    .split(',')
+    .map((role) => role.trim().toLowerCase())
+    .filter(Boolean);
+  return allowed.includes(roomRole.trim().toLowerCase());
+}
+
+export function resolveCodexRuntimeMode(
+  env: CodexRuntimeEnv,
+  input: CodexRuntimeModeInput,
+  rawPrompt: string,
+): CodexRuntimeModeResolution {
+  const requested = normalizeRuntimeMode(env.CODEX_RUNTIME);
+  if (requested === 'sdk') {
+    if (rawPrompt.trim() === '/compact') {
+      return {
+        mode: 'app-server',
+        reason: 'sdk-unsupported-session-command',
+      };
+    }
+    if (input.codexGoals === true) {
+      return { mode: 'app-server', reason: 'sdk-unsupported-goals' };
+    }
+    if (!sdkRoleEnabled(env, input.roomRole)) {
+      return { mode: 'app-server', reason: 'sdk-role-not-enabled' };
+    }
+    return { mode: 'sdk', reason: 'CODEX_RUNTIME=sdk' };
+  }
+
+  if (requested === 'app-server') {
+    return { mode: 'app-server', reason: 'CODEX_RUNTIME=app-server' };
+  }
+
+  if (env.CODEX_RUNTIME && env.CODEX_RUNTIME.trim()) {
+    return { mode: 'app-server', reason: 'invalid-CODEX_RUNTIME' };
+  }
+
+  return { mode: 'app-server', reason: 'default' };
+}
diff --git a/runners/codex-runner/test/runtime-mode.test.ts b/runners/codex-runner/test/runtime-mode.test.ts
new file mode 100644
index 0000000..40e4245
--- /dev/null
+++ b/runners/codex-runner/test/runtime-mode.test.ts
@@ -0,0 +1,64 @@
+import { describe, expect, it } from 'vitest';
+
+import { resolveCodexRuntimeMode } from '../src/runtime-mode.js';
+
+describe('codex runner runtime mode selection', () => {
+  it('keeps app-server as the default runtime', () => {
+    expect(
+      resolveCodexRuntimeMode({}, { codexGoals: false }, 'do work'),
+    ).toEqual({
+      mode: 'app-server',
+      reason: 'default',
+    });
+  });
+
+  it('selects SDK mode when CODEX_RUNTIME=sdk', () => {
+    expect(
+      resolveCodexRuntimeMode(
+        { CODEX_RUNTIME: 'sdk' },
+        { codexGoals: false },
+        'do work',
+      ),
+    ).toEqual({ mode: 'sdk', reason: 'CODEX_RUNTIME=sdk' });
+  });
+
+  it('canary-limits SDK mode to configured paired roles', () => {
+    expect(
+      resolveCodexRuntimeMode(
+        { CODEX_RUNTIME: 'sdk', CODEX_RUNTIME_SDK_ROLES: 'owner,arbiter' },
+        { codexGoals: false, roomRole: 'owner' },
+        'do work',
+      ),
+    ).toEqual({ mode: 'sdk', reason: 'CODEX_RUNTIME=sdk' });
+    expect(
+      resolveCodexRuntimeMode(
+        { CODEX_RUNTIME: 'sdk', CODEX_RUNTIME_SDK_ROLES: 'owner,arbiter' },
+        { codexGoals: false, roomRole: 'reviewer' },
+        'do work',
+      ),
+    ).toEqual({ mode: 'app-server', reason: 'sdk-role-not-enabled' });
+  });
+
+  it('falls back to app-server for /compact because SDK lacks compaction', () => {
+    expect(
+      resolveCodexRuntimeMode(
+        { CODEX_RUNTIME: 'sdk' },
+        { codexGoals: false },
+        '/compact',
+      ),
+    ).toEqual({
+      mode: 'app-server',
+      reason: 'sdk-unsupported-session-command',
+    });
+  });
+
+  it('falls back to app-server when Codex goals are enabled', () => {
+    expect(
+      resolveCodexRuntimeMode(
+        { CODEX_RUNTIME: 'sdk' },
+        { codexGoals: true },
+        'do work',
+      ),
+    ).toEqual({ mode: 'app-server', reason: 'sdk-unsupported-goals' });
+  });
+});
diff --git a/runners/codex-runner/test/sdk-client.test.ts b/runners/codex-runner/test/sdk-client.test.ts
new file mode 100644
index 0000000..243a509
--- /dev/null
+++ b/runners/codex-runner/test/sdk-client.test.ts
@@ -0,0 +1,194 @@
+import { describe, expect, it } from 'vitest';
+
+import {
+  CodexSdkClient,
+  createInitialCodexSdkTurnState,
+  reduceCodexSdkTurnState,
+  toCodexSdkInput,
+  type CodexSdkThreadPort,
+} from '../src/codex-sdk-client.js';
+
+const usage = {
+  input_tokens: 1,
+  cached_input_tokens: 0,
+  output_tokens: 2,
+  reasoning_output_tokens: 0,
+};
+
+async function* events(items: unknown[]): AsyncGenerator<unknown> {
+  for (const item of items) {
+    yield item;
+  }
+}
+
+class FakeThread implements CodexSdkThreadPort {
+  id: string | null = null;
+  lastInput: unknown = null;
+  lastSignal: AbortSignal | undefined;
+
+  constructor(private readonly scriptedEvents: unknown[]) {}
+
+  async runStreamed(input: unknown, options?: { signal?: AbortSignal }) {
+    this.lastInput = input;
+    this.lastSignal = options?.signal;
+    return { events: events(this.scriptedEvents) };
+  }
+}
+
+class FakeCodex {
+  readonly started: unknown[] = [];
+  readonly resumed: unknown[] = [];
+  readonly threads: FakeThread[] = [];
+
+  constructor(private readonly scriptedEvents: unknown[]) {}
+
+  startThread(options?: unknown): FakeThread {
+    this.started.push(options);
+    const thread = new FakeThread(this.scriptedEvents);
+    this.threads.push(thread);
+    return thread;
+  }
+
+  resumeThread(id: string, options?: unknown): FakeThread {
+    this.resumed.push({ id, options });
+    const thread = new FakeThread(this.scriptedEvents);
+    thread.id = id;
+    this.threads.push(thread);
+    return thread;
+  }
+}
+
+describe('Codex SDK runner spike', () => {
+  it('maps existing app-server text/image input into Codex SDK input shape', () => {
+    expect(
+      toCodexSdkInput([
+        { type: 'text', text: 'inspect this' },
+        { type: 'localImage', path: '/tmp/screenshot.png' },
+      ]),
+    ).toEqual([
+      { type: 'text', text: 'inspect this' },
+      { type: 'local_image', path: '/tmp/screenshot.png' },
+    ]);
+  });
+
+  it('reduces SDK thread events into the runner final result and thread id', () => {
+    let state = createInitialCodexSdkTurnState();
+    state = reduceCodexSdkTurnState(state, {
+      type: 'thread.started',
+      thread_id: 'thread-1',
+    });
+    state = reduceCodexSdkTurnState(state, { type: 'turn.started' });
+    state = reduceCodexSdkTurnState(state, {
+      type: 'item.completed',
+      item: {
+        id: 'msg-1',
+        type: 'agent_message',
+        text: 'STEP_DONE\n검증 완료',
+      },
+    });
+    state = reduceCodexSdkTurnState(state, {
+      type: 'turn.completed',
+      usage,
+    });
+
+    expect(state).toMatchObject({
+      status: 'completed',
+      threadId: 'thread-1',
+      finalAnswer: 'STEP_DONE\n검증 완료',
+      usage,
+    });
+  });
+
+  it('runs a streamed SDK turn and returns the first real thread id', async () => {
+    const codex = new FakeCodex([
+      { type: 'thread.started', thread_id: 'thread-42' },
+      { type: 'turn.started' },
+      {
+        type: 'item.completed',
+        item: { id: 'msg-1', type: 'agent_message', text: 'TASK_DONE\nSDK_OK' },
+      },
+      { type: 'turn.completed', usage },
+    ]);
+    const client = new CodexSdkClient({
+      codex,
+      env: { PATH: '/usr/bin' },
+      log: () => undefined,
+    });
+
+    const handle = await client.startOrResumeThread(undefined, {
+      cwd: '/repo',
+      model: 'gpt-5.5',
+      effort: 'high',
+    });
+    const turn = await client.startTurn(
+      handle,
+      [{ type: 'text', text: 'respond' }],
+      { cwd: '/repo', model: 'gpt-5.5', effort: 'high' },
+    );
+
+    await expect(turn.wait()).resolves.toMatchObject({
+      threadId: 'thread-42',
+      result: 'TASK_DONE\nSDK_OK',
+      state: { status: 'completed' },
+    });
+    expect(codex.started).toEqual([
+      {
+        approvalPolicy: 'never',
+        model: 'gpt-5.5',
+        modelReasoningEffort: 'high',
+        networkAccessEnabled: true,
+        sandboxMode: 'danger-full-access',
+        workingDirectory: '/repo',
+      },
+    ]);
+    expect(codex.threads[0].lastInput).toEqual([
+      { type: 'text', text: 'respond' },
+    ]);
+  });
+
+  it('coerces minimal effort to low because Codex SDK exec keeps tools enabled', async () => {
+    const codex = new FakeCodex([
+      { type: 'thread.started', thread_id: 'thread-minimal' },
+      { type: 'turn.started' },
+      {
+        type: 'item.completed',
+        item: { id: 'msg-1', type: 'agent_message', text: 'SDK_OK' },
+      },
+      { type: 'turn.completed', usage },
+    ]);
+    const client = new CodexSdkClient({ codex, log: () => undefined });
+
+    await client.startOrResumeThread(undefined, {
+      cwd: '/repo',
+      effort: 'minimal',
+    });
+
+    expect(codex.started[0]).toMatchObject({ modelReasoningEffort: 'low' });
+  });
+
+  it('documents the SDK gap: mid-turn steering is not available', async () => {
+    const codex = new FakeCodex([
+      { type: 'thread.started', thread_id: 'thread-1' },
+      { type: 'turn.started' },
+      { type: 'turn.completed', usage },
+    ]);
+    const client = new CodexSdkClient({ codex, log: () => undefined });
+    const handle = await client.startOrResumeThread('thread-1', {
+      cwd: '/repo',
+    });
+    const turn = await client.startTurn(
+      handle,
+      [{ type: 'text', text: 'start' }],
+      {
+        cwd: '/repo',
+      },
+    );
+
+    await expect(
+      turn.steer([{ type: 'text', text: 'follow-up' }]),
+    ).rejects.toThrow('Codex SDK runner does not support mid-turn steering');
+    await expect(turn.wait()).resolves.toMatchObject({
+      state: { status: 'completed' },
+    });
+  });
+});
diff --git a/spikes/001-codex-sdk-runner/README.md b/spikes/001-codex-sdk-runner/README.md
new file mode 100644
index 0000000..ec5767c
--- /dev/null
+++ b/spikes/001-codex-sdk-runner/README.md
@@ -0,0 +1,81 @@
+# 001: codex-sdk-runner
+
+## Question
+
+Given EJClaw currently wraps `codex app-server` JSON-RPC directly, when we switch the runner core to the official `@openai/codex-sdk`, can we preserve the key runner guarantees: thread resume, final result extraction, cancellation, and structured event visibility?
+
+## Approach
+
+- Added `@openai/codex-sdk@0.136.0` beside `@openai/codex@0.136.0` in the codex runner workspace.
+- Built a `CodexSdkClient` adapter that maps EJClaw's existing app-server input shape into SDK input.
+- Added `CODEX_RUNTIME=sdk` runtime selection while keeping app-server as the default.
+- Added `CODEX_RUNTIME_SDK_ROLES=owner,arbiter` canary limiting so production can try SDK only on selected paired roles.
+- Fallbacks: `/compact` and `codexGoals` stay on app-server because SDK lacks those APIs.
+- Wrote unit tests around SDK event reduction, thread-id propagation, runtime selection, and unsupported steering.
+- Ran real smoke turns through both the SDK adapter and the integrated codex-runner entrypoint against temporary git repos.
+
+## Evidence
+
+Commands run:
+
+```bash
+bunx vitest run runners/codex-runner/test/sdk-client.test.ts
+bunx vitest run runners/codex-runner/test/runtime-mode.test.ts
+bunx tsc --noEmit -p runners/codex-runner/tsconfig.json
+bun run --cwd runners/codex-runner build
+bunx vitest run \
+  runners/codex-runner/test/app-server-client.test.ts \
+  runners/codex-runner/test/app-server-state.test.ts \
+  runners/codex-runner/test/runtime-mode.test.ts \
+  runners/codex-runner/test/sdk-client.test.ts
+bun run check
+CODEX_RUNTIME=sdk CODEX_EFFORT=minimal node runners/codex-runner/dist/index.js < /tmp/input.json
+```
+
+Observed adapter smoke result:
+
+```json
+{
+  "status": "completed",
+  "result": "SDK_OK",
+  "error": null
+}
+```
+
+Observed integrated runner smoke result:
+
+```json
+{
+  "status": "success",
+  "result": "SDK_RUNNER_OK",
+  "phase": "final",
+  "newSessionId": "019e..."
+}
+```
+
+## What worked
+
+- SDK import and runner workspace build work on Node/Bun in this repo.
+- SDK streaming events can be reduced into EJClaw-style `status`, `threadId`, `result`, `error`, and `usage`.
+- `thread.started` gives the real thread id during the first streamed turn, so a pending local handle can be replaced with the real session id.
+- `AbortController` gives a clean replacement for close-sentinel cancellation.
+- Real SDK smoke and integrated runner smoke completed successfully.
+- Runtime flag selection works: default app-server; `CODEX_RUNTIME=sdk` selects SDK; `CODEX_RUNTIME_SDK_ROLES` canaries SDK to chosen paired roles; `/compact` and goals fall back to app-server.
+
+## What did not work / gaps
+
+- SDK does **not** expose app-server `turn/steer`; mid-turn Discord follow-up steering would need to be queued for the next turn or stay on the app-server path.
+- SDK TypeScript wrapper uses `codex exec --experimental-json`, not persistent `codex app-server`, so process-per-turn overhead and session behavior must be measured under real long tasks.
+- Passing `modelReasoningEffort: "minimal"` failed in live smoke because Codex exec still enabled tools that are incompatible with minimal reasoning. The spike adapter coerces `minimal` to `low`.
+- Existing Codex app-server-only features (`thread/goal/*`, `thread/compact/start`) are not available through the current SDK API.
+
+## Verdict: FEATURE-FLAGGED
+
+SDK is now viable as an optional **exec-backed Codex runner lane** behind `CODEX_RUNTIME=sdk`. The default remains app-server, and `CODEX_RUNTIME_SDK_ROLES=owner,arbiter` can limit SDK to safer paired roles while reviewer/non-paired turns keep the old path.
+
+## Recommended rollout
+
+1. Merge as a draft/feature-flagged implementation without changing production env.
+2. Enable `CODEX_RUNTIME=sdk` for one low-risk owner/arbiter lane first.
+3. Keep app-server mode for rooms/tasks that require live steering, goals, or compaction.
+4. Watch `turn.failed`, `error`, `item.completed:error`, empty final output, and process-per-turn latency before promoting SDK broadly.