diff --git a/src/codex/auth-api.ts b/src/codex/auth-api.ts
index c996aab96f4..59833b1e7f5 100644
--- a/src/codex/auth-api.ts
+++ b/src/codex/auth-api.ts
@@ -33,7 +33,6 @@ export {
 } from "./auth-api/pool-mode-gate";
 export { createResetCreditWhamClient } from "./auth-api/reset-credit-service";
 export type { CodexAuthCatalogConvergence } from "./auth-api/login-flow";
-export { handleCodexAuthAPI } from "./auth-api/routes";
 import { getEffectiveActiveCodexAccountId } from "./routing";
 import { MAIN_CODEX_ACCOUNT_ID } from "./main-account";
 import type { OcxConfig } from "../types";
diff --git a/src/oauth/chatgpt-device.ts b/src/oauth/chatgpt-device.ts
index 8151a123548..88c5fc2b514 100644
--- a/src/oauth/chatgpt-device.ts
+++ b/src/oauth/chatgpt-device.ts
@@ -1,5 +1,5 @@
 import type { OAuthController, OAuthCredentials } from "./types";
-import { CHATGPT_CLIENT_ID, CHATGPT_TOKEN_URL, credsFromToken } from "./chatgpt";
+import { CHATGPT_CLIENT_ID, CHATGPT_TOKEN_URL, credsFromToken } from "./chatgpt-shared";
 
 /**
  * OpenAI deviceauth (device-code) grant for the ChatGPT/Codex provider.
diff --git a/src/oauth/chatgpt-shared.ts b/src/oauth/chatgpt-shared.ts
new file mode 100644
index 00000000000..be43bd30be6
--- /dev/null
+++ b/src/oauth/chatgpt-shared.ts
@@ -0,0 +1,83 @@
+import type { OAuthCredentials } from "./types";
+
+/**
+ * What the browser callback grant and the deviceauth grant share: the public PKCE client and the
+ * way a token response becomes credentials.
+ *
+ * This is a leaf on purpose. `./chatgpt-device` needs these, and `./chatgpt` needs the device
+ * grant for `flow: "device"`; importing them straight from `./chatgpt` made the pair a cycle.
+ */
+
+const CLIENT_ID = "app_EMoamEEZ73f0CkXaXp7hrann";
+const TOKEN_URL = "https://auth.openai.com/oauth/token";
+
+/** Shared with the deviceauth grant in `./chatgpt-device`: same public PKCE client. */
+export const CHATGPT_CLIENT_ID = CLIENT_ID;
+export const CHATGPT_TOKEN_URL = TOKEN_URL;
+
+export function decodeJwtPayload(token: string): Record<string, unknown> | undefined {
+  const parts = token.split(".");
+  if (parts.length !== 3 || !parts[1]) return undefined;
+  try {
+    return JSON.parse(Buffer.from(parts[1], "base64url").toString("utf8")) as Record<string, unknown>;
+  } catch {
+    return undefined;
+  }
+}
+
+export function extractAccountId(idToken?: string, accessToken?: string): string | undefined {
+  for (const token of [idToken, accessToken]) {
+    if (!token) continue;
+    const payload = decodeJwtPayload(token);
+    if (!payload) continue;
+    if (typeof payload.chatgpt_account_id === "string") return payload.chatgpt_account_id;
+    const ns = payload["https://api.openai.com/auth"];
+    if (ns && typeof ns === "object" && typeof (ns as Record<string, unknown>).chatgpt_account_id === "string") {
+      return (ns as Record<string, unknown>).chatgpt_account_id as string;
+    }
+    const orgs = payload.organizations;
+    if (Array.isArray(orgs) && orgs[0] && typeof orgs[0].id === "string") return orgs[0].id as string;
+  }
+  return undefined;
+}
+
+export function extractEmail(idToken?: string, accessToken?: string): string | undefined {
+  for (const token of [idToken, accessToken]) {
+    if (!token) continue;
+    const payload = decodeJwtPayload(token);
+    if (!payload) continue;
+    if (typeof payload.email === "string") return payload.email.toLowerCase();
+  }
+  return undefined;
+}
+
+export function credsFromToken(data: Record<string, unknown>): OAuthCredentials {
+  const idToken = typeof data.id_token === "string" ? data.id_token : undefined;
+  // This parses a response from an external boundary, so the access token is
+  // validated rather than cast. A 200 carrying no access_token would otherwise
+  // resolve a login as successful with an undefined credential, which then gets
+  // silently declined at persistence — a success message and no account.
+  const accessToken = typeof data.access_token === "string" && data.access_token.length > 0
+    ? data.access_token
+    : undefined;
+  if (!accessToken) throw new Error("ChatGPT token response missing access token");
+  const refreshToken = typeof data.refresh_token === "string" ? data.refresh_token : "";
+  // ?? only guards null/undefined; NaN or a string expires_in would otherwise
+  // produce a NaN expiry that never compares as expired, and a negative duration
+  // would stamp an already-past expiry — both block refresh semantics.
+  const expiresIn =
+    typeof data.expires_in === "number" && Number.isFinite(data.expires_in) && data.expires_in >= 0
+      ? data.expires_in
+      : 3600;
+  // The computed timestamp itself must stay finite: Number.MAX_VALUE passes
+  // Number.isFinite but overflows to Infinity once multiplied by 1000.
+  const computedExpires = Date.now() + expiresIn * 1000;
+  const expires = Number.isFinite(computedExpires) ? computedExpires : Date.now() + 3600 * 1000;
+  return {
+    access: accessToken,
+    refresh: refreshToken,
+    expires,
+    accountId: extractAccountId(idToken, accessToken),
+    email: extractEmail(idToken, accessToken),
+  };
+}
diff --git a/src/oauth/chatgpt.ts b/src/oauth/chatgpt.ts
index 2b745f25ae5..cfe8c908d4a 100644
--- a/src/oauth/chatgpt.ts
+++ b/src/oauth/chatgpt.ts
@@ -1,4 +1,5 @@
 import { OAuthCallbackFlow } from "./callback-server";
+import { CHATGPT_CLIENT_ID, CHATGPT_TOKEN_URL, credsFromToken, decodeJwtPayload, extractAccountId, extractEmail } from "./chatgpt-shared";
 import type { OAuthController, OAuthCredentials } from "./types";
 import { generatePKCE } from "./pkce";
 import { classifyChatgptRefreshFailure } from "../codex/chatgpt-refresh-failure";
@@ -102,44 +103,20 @@ function chatGptTokenError(status: number, body: string, label: string): ChatGpt
   );
 }
 
-const CLIENT_ID = "app_EMoamEEZ73f0CkXaXp7hrann";
+/**
+ * The client and token decoding live in a leaf shared with the device grant.
+ * Re-exported so existing import sites keep their public helper surface.
+ */
+export { CHATGPT_CLIENT_ID, CHATGPT_TOKEN_URL, credsFromToken, decodeJwtPayload, extractAccountId, extractEmail };
+const CLIENT_ID = CHATGPT_CLIENT_ID;
 const AUTH_URL = "https://auth.openai.com/oauth/authorize";
-const TOKEN_URL = "https://auth.openai.com/oauth/token";
+const TOKEN_URL = CHATGPT_TOKEN_URL;
 
-/** Shared with the deviceauth grant in `./chatgpt-device`: same public PKCE client. */
-export const CHATGPT_CLIENT_ID = CLIENT_ID;
-export const CHATGPT_TOKEN_URL = TOKEN_URL;
 const SCOPE = "openid profile email offline_access api.connectors.read api.connectors.invoke";
 const CALLBACK_PORT = 1455;
 const CALLBACK_PATH = "/auth/callback";
 const ORIGINATOR = "opencodex";
 
-export function decodeJwtPayload(token: string): Record<string, unknown> | undefined {
-  const parts = token.split(".");
-  if (parts.length !== 3 || !parts[1]) return undefined;
-  try {
-    return JSON.parse(Buffer.from(parts[1], "base64url").toString("utf8")) as Record<string, unknown>;
-  } catch {
-    return undefined;
-  }
-}
-
-export function extractAccountId(idToken?: string, accessToken?: string): string | undefined {
-  for (const token of [idToken, accessToken]) {
-    if (!token) continue;
-    const payload = decodeJwtPayload(token);
-    if (!payload) continue;
-    if (typeof payload.chatgpt_account_id === "string") return payload.chatgpt_account_id;
-    const ns = payload["https://api.openai.com/auth"];
-    if (ns && typeof ns === "object" && typeof (ns as Record<string, unknown>).chatgpt_account_id === "string") {
-      return (ns as Record<string, unknown>).chatgpt_account_id as string;
-    }
-    const orgs = payload.organizations;
-    if (Array.isArray(orgs) && orgs[0] && typeof orgs[0].id === "string") return orgs[0].id as string;
-  }
-  return undefined;
-}
-
 /**
  * Three-way answer to "is this token marked as belonging to the ChatGPT account domain".
  * Only ChatGPT-specific claims count as markers: a top-level chatgpt_account_id or the
@@ -196,16 +173,6 @@ export function inspectChatGptDomainClaim(token: string): ChatGptDomainClaim {
   return accountId ? { kind: "valid", accountId } : { kind: "invalid" };
 }
 
-export function extractEmail(idToken?: string, accessToken?: string): string | undefined {
-  for (const token of [idToken, accessToken]) {
-    if (!token) continue;
-    const payload = decodeJwtPayload(token);
-    if (!payload) continue;
-    if (typeof payload.email === "string") return payload.email.toLowerCase();
-  }
-  return undefined;
-}
-
 /**
  * Identity-agreement view of one token for security-sensitive bindings. `accountId` follows the
  * existing extractAccountId precedence (top-level, then namespaced, then organizations[0]).
@@ -233,37 +200,6 @@ export function extractAccountIdClaims(token?: string): { accountId: string | un
   };
 }
 
-export function credsFromToken(data: Record<string, unknown>): OAuthCredentials {
-  const idToken = typeof data.id_token === "string" ? data.id_token : undefined;
-  // This parses a response from an external boundary, so the access token is
-  // validated rather than cast. A 200 carrying no access_token would otherwise
-  // resolve a login as successful with an undefined credential, which then gets
-  // silently declined at persistence — a success message and no account.
-  const accessToken = typeof data.access_token === "string" && data.access_token.length > 0
-    ? data.access_token
-    : undefined;
-  if (!accessToken) throw new Error("ChatGPT token response missing access token");
-  const refreshToken = typeof data.refresh_token === "string" ? data.refresh_token : "";
-  // ?? only guards null/undefined; NaN or a string expires_in would otherwise
-  // produce a NaN expiry that never compares as expired, and a negative duration
-  // would stamp an already-past expiry — both block refresh semantics.
-  const expiresIn =
-    typeof data.expires_in === "number" && Number.isFinite(data.expires_in) && data.expires_in >= 0
-      ? data.expires_in
-      : 3600;
-  // The computed timestamp itself must stay finite: Number.MAX_VALUE passes
-  // Number.isFinite but overflows to Infinity once multiplied by 1000.
-  const computedExpires = Date.now() + expiresIn * 1000;
-  const expires = Number.isFinite(computedExpires) ? computedExpires : Date.now() + 3600 * 1000;
-  return {
-    access: accessToken,
-    refresh: refreshToken,
-    expires,
-    accountId: extractAccountId(idToken, accessToken),
-    email: extractEmail(idToken, accessToken),
-  };
-}
-
 export class ChatGPTOAuthFlow extends OAuthCallbackFlow {
   #verifier = "";
   forceLogin = false;
diff --git a/src/oauth/index.ts b/src/oauth/index.ts
index 63809facab0..8309e1a30fc 100644
--- a/src/oauth/index.ts
+++ b/src/oauth/index.ts
@@ -1786,7 +1786,7 @@ export async function runLogin(
   if (provider !== "chatgpt") {
     try {
       const { clearModelCache } = await import("../codex/model-cache");
-      const { clearGatherRoutedModelsInflight } = await import("../codex/catalog");
+      const { clearGatherRoutedModelsInflight } = await import("../codex/catalog/routed-gather");
       clearModelCache(provider);
       clearGatherRoutedModelsInflight();
       const { clearAccountQuotaCache, clearProviderQuotaCache } = await import("../providers/quota");
diff --git a/src/server/management-api.ts b/src/server/management-api.ts
index 976f327062d..f6076920a48 100644
--- a/src/server/management-api.ts
+++ b/src/server/management-api.ts
@@ -521,7 +521,7 @@ export async function handleManagementAPI(
       const { handleMainDeviceReauthAPI } = await import("../codex/main-device-reauth-api");
       return handleMainDeviceReauthAPI(req, url, config);
     }
-    const { handleCodexAuthAPI } = await import("../codex/auth-api");
+    const { handleCodexAuthAPI } = await import("../codex/auth-api/routes");
     const { ConfigMutationLockError } = await import("../config");
     const { CodexCredentialRefreshLockTimeoutError } = await import("../codex/account-store");
     try {
diff --git a/structure/runtime.md b/structure/runtime.md
index fdbbf039411..16131ceedae 100644
--- a/structure/runtime.md
+++ b/structure/runtime.md
@@ -139,7 +139,7 @@ there. Feature code is grouped by responsibility:
 | Group | Directories |
 | --- | --- |
 | Data plane | `src/adapters/`, `src/responses/`, `src/chat/`, `src/claude/`, `src/grok/`, `src/images/`, `src/vision/`, `src/web-search/` |
-| Codex integration | `src/codex/`, `src/combos/`, `src/providers/`, `src/oauth/` |
+| Codex integration | `src/codex/`, `src/combos/`, `src/providers/`, `src/oauth/`. Browser/device grants share unchanged credential helpers in the type-only-dependent `src/oauth/chatgpt-shared.ts` leaf; `src/oauth/chatgpt.ts` retains their exports and the bounded token-request logic. Management dispatch imports `src/codex/auth-api/routes.ts` directly, without an auth-api handler re-export; OAuth cache invalidation imports `src/codex/catalog/routed-gather.ts` directly. |
 | Surfaces | `src/server/`, `src/cli/`, `src/tray/`, `src/github/` |
 | Evidence and contracts | `src/compatibility/`, `src/lab/` |
 | Support | `src/lib/`, `src/storage/` (Worker policy fixtures synchronize after loading the initial policy; `src/storage/policy.ts` bounds the test barrier at 10 seconds), `src/usage/`, `src/update/` (compiled executables report standalone update guidance rather than a source checkout; [package refresh](ops/service-and-sidecars.md#package-cache-refresh); `desktop-badge.ts` holds bounded process-local display state, never install authority), `src/generated/` |
diff --git a/tests/ci-workflows/import-cycle-ratchet.test.ts b/tests/ci-workflows/import-cycle-ratchet.test.ts
index f189708b445..64aeb402dce 100644
--- a/tests/ci-workflows/import-cycle-ratchet.test.ts
+++ b/tests/ci-workflows/import-cycle-ratchet.test.ts
@@ -27,6 +27,7 @@ import { repoRoot } from "../helpers/repo-root";
  */
 const CORE_OFF_CYCLE = [
   "src/config.ts",
+  "src/router.ts",
   "src/server/lifecycle.ts",
   "src/server/responses/core.ts",
   "src/server/management-api.ts",
diff --git a/tests/codex-integration/codex-auth-release.test.ts b/tests/codex-integration/codex-auth-release.test.ts
index c19f4fbfc30..1b03fe4b596 100644
--- a/tests/codex-integration/codex-auth-release.test.ts
+++ b/tests/codex-integration/codex-auth-release.test.ts
@@ -5,7 +5,7 @@ import { join } from "node:path";
 import { getConfigPath } from "../../src/config";
 import { setPersistedConfigMutationBeforeCommitForTests } from "../../src/config/persisted-mutation";
 import * as mutationLock from "../../src/config/mutation-lock";
-import { handleCodexAuthAPI } from "../../src/codex/auth-api";
+import { handleCodexAuthAPI } from "../../src/codex/auth-api/routes";
 import { saveCodexAccountCredential } from "../../src/codex/account-store";
 import {
   clearCodexUpstreamHealth,
diff --git a/tests/codex-integration/codex-linked-account-pause.test.ts b/tests/codex-integration/codex-linked-account-pause.test.ts
index 9996a224ae6..3bed76d4f71 100644
--- a/tests/codex-integration/codex-linked-account-pause.test.ts
+++ b/tests/codex-integration/codex-linked-account-pause.test.ts
@@ -5,7 +5,8 @@ import { join } from "node:path";
 import type { OcxConfig } from "../../src/types";
 import { loadConfig } from "../../src/config";
 import { flushConfigDirHardeningForTests } from "../../src/config/paths";
-import { handleCodexAuthAPI, clearAccountQuota, updateAccountQuota } from "../../src/codex/auth-api";
+import { handleCodexAuthAPI } from "../../src/codex/auth-api/routes";
+import { clearAccountQuota, updateAccountQuota } from "../../src/codex/auth-api";
 import { getCodexAccountCredential, saveCodexAccountCredential } from "../../src/codex/account-store";
 import { MAIN_CODEX_ACCOUNT_ID, setMainAccountPlan } from "../../src/codex/main-account";
 import { clearCodexUpstreamHealth, clearThreadAccountMap, resolveCodexAccountForThread } from "../../src/codex/routing";
diff --git a/tests/codex-integration/codex-main-token-invalidated.test.ts b/tests/codex-integration/codex-main-token-invalidated.test.ts
index 2554a0500ec..bb57d586343 100644
--- a/tests/codex-integration/codex-main-token-invalidated.test.ts
+++ b/tests/codex-integration/codex-main-token-invalidated.test.ts
@@ -2,8 +2,9 @@ import { afterEach, beforeEach, expect, test } from "bun:test";
 import { mkdirSync, mkdtempSync, writeFileSync } from "node:fs";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
+import { handleCodexAuthAPI } from "../../src/codex/auth-api/routes";
 import {
-  clearAccountNeedsReauth, clearMainAccountInfoCache, handleCodexAuthAPI, isAccountNeedsReauth, markAccountNeedsReauth,
+  clearAccountNeedsReauth, clearMainAccountInfoCache, isAccountNeedsReauth, markAccountNeedsReauth,
   type CodexAuthAccountDto,
 } from "../../src/codex/auth-api";
 import { MAIN_CODEX_ACCOUNT_ID, setMainAccountPlan } from "../../src/codex/main-account";
diff --git a/tests/codex-integration/codex-preserve-signed-in.test.ts b/tests/codex-integration/codex-preserve-signed-in.test.ts
index 5a658ee3e05..d454b031440 100644
--- a/tests/codex-integration/codex-preserve-signed-in.test.ts
+++ b/tests/codex-integration/codex-preserve-signed-in.test.ts
@@ -7,7 +7,8 @@ import { getDefaultConfig } from "../../src/config/proxy-env";
 import { loadConfig } from "../../src/config";
 import { configSchema } from "../../src/config/schema/config-schema";
 import { flushConfigDirHardeningForTests } from "../../src/config/paths";
-import { handleCodexAuthAPI, clearAccountQuota, updateAccountQuota } from "../../src/codex/auth-api";
+import { clearAccountQuota, updateAccountQuota } from "../../src/codex/auth-api";
+import { handleCodexAuthAPI } from "../../src/codex/auth-api/routes";
 import { saveCodexAccountCredential } from "../../src/codex/account-store";
 import * as runtimeConfig from "../../src/codex/auth-api/runtime-config";
 import * as authRead from "../../src/codex/auth-collision";
diff --git a/tests/codex-integration/codex-use-remaining-quota.test.ts b/tests/codex-integration/codex-use-remaining-quota.test.ts
index 2d4debd0074..b6958348922 100644
--- a/tests/codex-integration/codex-use-remaining-quota.test.ts
+++ b/tests/codex-integration/codex-use-remaining-quota.test.ts
@@ -12,7 +12,7 @@ import { observeCodexLowQuota } from "../../src/codex/low-quota-observer";
 import { clearAccountNeedsReauth, markAccountNeedsReauth } from "../../src/codex/account-runtime-state";
 import { clearPoolRotationState } from "../../src/codex/pool-rotation";
 import { deleteCodexAccount } from "../../src/codex/account-lifecycle";
-import { handleCodexAuthAPI } from "../../src/codex/auth-api";
+import { handleCodexAuthAPI } from "../../src/codex/auth-api/routes";
 import { configSchema } from "../../src/config/schema/config-schema";
 import { validateConfigCandidate } from "../../src/config/diagnostics";
 import { requireManagementAuth, type ManagementAuthState } from "../../src/server/management-auth";
diff --git a/tests/fixtures/import-cycle-baseline.json b/tests/fixtures/import-cycle-baseline.json
index bd453aed1ec..48711f0273f 100644
--- a/tests/fixtures/import-cycle-baseline.json
+++ b/tests/fixtures/import-cycle-baseline.json
@@ -5,21 +5,9 @@
     "src/codex/account-lifecycle.ts",
     "src/codex/auth-api.ts",
     "src/codex/auth-api/account-list.ts",
-    "src/codex/auth-api/login-flow.ts",
-    "src/codex/auth-api/routes.ts",
-    "src/codex/catalog/aggregation.ts",
     "src/codex/catalog/bundled.ts",
-    "src/codex/catalog/combo-member.ts",
-    "src/codex/catalog/configured-tiers.ts",
-    "src/codex/catalog/effort.ts",
-    "src/codex/catalog/gather-capture.ts",
     "src/codex/catalog/metadata.ts",
-    "src/codex/catalog/model-hints.ts",
-    "src/codex/catalog/model-visibility.ts",
     "src/codex/catalog/parsing.ts",
-    "src/codex/catalog/provider-fetch.ts",
-    "src/codex/catalog/provider-models.ts",
-    "src/codex/catalog/routed-gather.ts",
     "src/codex/inject.ts",
     "src/codex/inject/config-write-section.ts",
     "src/codex/inject/restore.ts",
@@ -27,19 +15,14 @@
     "src/codex/main-account.ts",
     "src/codex/native-profile-manager.ts",
     "src/codex/native-profile-startup.ts",
-    "src/codex/subagent-model-fallback.ts",
     "src/grok/inject.ts",
     "src/integrations/native/ownership-preflight.ts",
-    "src/lib/state-store-registrations.ts",
     "src/oauth/anthropic-model-quota.ts",
     "src/oauth/anthropic-routing.ts",
     "src/oauth/devin.ts",
     "src/oauth/health.ts",
     "src/oauth/index.ts",
-    "src/oauth/token-guardian.ts",
-    "src/providers/key-failover.ts",
     "src/providers/kiro-account-state-disk.ts",
-    "src/providers/kiro-model-catalog.ts",
     "src/providers/kiro-usage.ts",
     "src/providers/quota.ts",
     "src/providers/quota/account-cache.ts",
@@ -50,14 +33,7 @@
     "src/providers/quota/report-cache.ts",
     "src/providers/quota/vendor-probes-key.ts",
     "src/providers/quota/vendor-probes-oauth.ts",
-    "src/router.ts",
-    "src/routing/capability.ts",
-    "src/routing/compatibility/assemble.ts",
-    "src/routing/evaluator.ts",
-    "src/routing/quota.ts",
-    "src/server/effort-policy.ts",
     "src/service.ts",
-    "src/service/cli.ts",
-    "src/vision/eligibility.ts"
+    "src/service/cli.ts"
   ]
 }
diff --git a/tests/oauth/chatgpt-oauth.test.ts b/tests/oauth/chatgpt-oauth.test.ts
index 29f35f808d6..1763a512739 100644
--- a/tests/oauth/chatgpt-oauth.test.ts
+++ b/tests/oauth/chatgpt-oauth.test.ts
@@ -115,14 +115,16 @@ describe("ChatGPT OAuth JWT helpers", () => {
 
 describe("ChatGPT OAuth constants", () => {
   test("uses auth.openai.com endpoints (not auth0.openai.com)", async () => {
-    const source = await Bun.file("src/oauth/chatgpt.ts").text();
+    const source = await Bun.file("src/oauth/chatgpt.ts").text()
+      + await Bun.file("src/oauth/chatgpt-shared.ts").text();
     expect(source).toContain('auth.openai.com/oauth/authorize');
     expect(source).toContain('auth.openai.com/oauth/token');
     expect(source).not.toContain("auth0.openai.com");
   });
 
   test("uses official Codex client_id", async () => {
-    const source = await Bun.file("src/oauth/chatgpt.ts").text();
+    const source = await Bun.file("src/oauth/chatgpt.ts").text()
+      + await Bun.file("src/oauth/chatgpt-shared.ts").text();
     expect(source).toContain("app_EMoamEEZ73f0CkXaXp7hrann");
     expect(source).not.toContain("DRivsnm2Mu42T3KOpqdtwB3NYviHYzwD");
   });