diff --git a/apps/desktop/src/demo/api.ts b/apps/desktop/src/demo/api.ts
index cc21e8f..7323793 100644
--- a/apps/desktop/src/demo/api.ts
+++ b/apps/desktop/src/demo/api.ts
@@ -1,6 +1,7 @@
 import type {
   CallDetail,
   CursorHarnessStatus,
+  ExternalApiSettings,
   LlmCall,
   Model,
   Overview,
@@ -86,6 +87,7 @@ let harnessStatus: CursorHarnessStatus = {
 
 let detailed = true;
 let portSettings = { proxy_port: 0, service_port: 0 };
+let externalApiSettings: ExternalApiSettings = { enabled: false, api_key: "" };
 let proxySettings: ProxySettings = {
   mode: "default",
   address: "",
@@ -148,6 +150,11 @@ export function installDemoApi() {
       portSettings = body as typeof portSettings;
       return json(portSettings);
     }
+    if (path === "/settings/external-api" && method === "GET") return json(externalApiSettings);
+    if (path === "/settings/external-api") {
+      externalApiSettings = body as ExternalApiSettings;
+      return json(externalApiSettings);
+    }
     if (path === "/settings/storage/statistics" && method === "GET") return json(storage);
     if (path === "/settings/storage/statistics") {
       const scope = (body as { scope?: string } | null)?.scope ?? "details";
diff --git a/apps/desktop/src/features/settings/ExternalApiSettingsCard.module.scss b/apps/desktop/src/features/settings/ExternalApiSettingsCard.module.scss
new file mode 100644
index 0000000..5999919
--- /dev/null
+++ b/apps/desktop/src/features/settings/ExternalApiSettingsCard.module.scss
@@ -0,0 +1,38 @@
+@use "../../styles/typography" as type;
+
+.content {
+  display: grid;
+  gap: 16px;
+  padding: 16px;
+}
+
+.row, .address {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  gap: 16px;
+  min-width: 0;
+}
+
+.description {
+  display: grid;
+  gap: 5px;
+  min-width: 0;
+
+  small {
+    color: var(--vscode-descriptionForeground);
+    font-size: type.$font-size-xs;
+  }
+}
+
+.address {
+  flex-wrap: wrap;
+
+  code {
+    flex: 1 1 240px;
+    min-width: 0;
+    overflow-wrap: anywhere;
+    color: var(--vscode-descriptionForeground);
+    font-size: type.$font-size-xs;
+  }
+}
diff --git a/apps/desktop/src/features/settings/ExternalApiSettingsCard.tsx b/apps/desktop/src/features/settings/ExternalApiSettingsCard.tsx
new file mode 100644
index 0000000..d96d0e9
--- /dev/null
+++ b/apps/desktop/src/features/settings/ExternalApiSettingsCard.tsx
@@ -0,0 +1,62 @@
+import { useEffect, useState } from "react";
+import { api, type ExternalApiSettings } from "../../shared/api";
+import { Button } from "../../shared/ui/Button";
+import { FormField, SecretTextInput } from "../../shared/ui/FormControls";
+import { Switch } from "../../shared/ui/Switch";
+import { TitledCard } from "../../shared/ui/TitledCard";
+import { useMessage } from "../../shared/ui/message";
+import styles from "./ExternalApiSettingsCard.module.scss";
+
+export function ExternalApiSettingsCard({ servicePort }: { servicePort: number }) {
+  const message = useMessage();
+  const [saved, setSaved] = useState<ExternalApiSettings | null>(null);
+  const [draft, setDraft] = useState<ExternalApiSettings>({ enabled: false, api_key: "" });
+  const [saving, setSaving] = useState(false);
+
+  useEffect(() => {
+    void api.externalApiSettings().then((settings) => {
+      setSaved(settings);
+      setDraft(settings);
+    }).catch((cause: unknown) => message(cause instanceof Error ? cause.message : String(cause)));
+  }, [message]);
+
+  const save = async () => {
+    try {
+      setSaving(true);
+      const settings = await api.setExternalApiSettings(draft);
+      setSaved(settings);
+      setDraft(settings);
+      message(t("外部 API 设置已保存"));
+    } catch (cause) {
+      message(cause instanceof Error ? cause.message : String(cause));
+    } finally {
+      setSaving(false);
+    }
+  };
+
+  const address = `http://127.0.0.1:${servicePort}/byok/v1`;
+  const changed = saved && (saved.enabled !== draft.enabled || saved.api_key !== draft.api_key);
+
+  return <TitledCard title={t("外部 API")} action={<Button size="small" variant="primary" disabled={!changed || saving} onClick={() => void save()}>
+    {saving ? t("保存中…") : t("保存")}
+  </Button>}>
+    <div className={styles.content}>
+      <div className={styles.row}>
+        <div className={styles.description}>
+          <strong>{t("开启外部 API")}</strong>
+          <small>{t("允许本机应用使用密钥调用已配置的模型，包括插件模型。")}</small>
+        </div>
+        <Switch label={t("开启外部 API")} checked={draft.enabled} disabled={!saved || saving}
+          onChange={(enabled) => setDraft((current) => ({ ...current, enabled }))} />
+      </div>
+      <FormField label={t("API 密钥")} hint={t("开启后，所有外部请求都必须提供此密钥。")}> 
+        <SecretTextInput value={draft.api_key} autoComplete="off" disabled={!saved || saving}
+          onChange={(event) => setDraft((current) => ({ ...current, api_key: event.target.value }))} />
+      </FormField>
+      <div className={styles.address}>
+        <strong>{t("基础地址")}</strong>
+        <code>{address}</code>
+      </div>
+    </div>
+  </TitledCard>;
+}
diff --git a/apps/desktop/src/features/settings/SettingsPage.tsx b/apps/desktop/src/features/settings/SettingsPage.tsx
index 212c2fd..20b0fd9 100644
--- a/apps/desktop/src/features/settings/SettingsPage.tsx
+++ b/apps/desktop/src/features/settings/SettingsPage.tsx
@@ -4,6 +4,7 @@ import { PageContent } from "../../shell/layout/PageContent";
 import { LegacyModelImport } from "../models/LegacyModelImport";
 import { AppLifecycleSettingsCard } from "./AppLifecycleSettingsCard";
 import { CommitSettingsCard } from "./CommitSettingsCard";
+import { ExternalApiSettingsCard } from "./ExternalApiSettingsCard";
 import { PricingSettingsCard } from "./PricingSettingsCard";
 import { ProxySettingsCard } from "./ProxySettingsCard";
 import { TabSettingsCard } from "./TabSettingsCard";
@@ -224,6 +225,7 @@ export function SettingsPage() {
           </div>
         </div>
       </TitledCard>
+      <ExternalApiSettingsCard servicePort={ports.service_port} />
       <ProxySettingsCard settings={outboundProxy} draft={proxyDraft} editing={editingProxy} saving={savingProxy} onDraftChange={setProxyDraft} onEdit={editProxy} onCancel={cancelProxyEdit} onSave={() => void saveProxy()} />
       <TabSettingsCard settings={tabSettings} draft={tabDraft} editing={editingTab} saving={savingTab} onDraftChange={setTabDraft} onEdit={editTab} onCancel={cancelTabEdit} onSave={() => void saveTab()} />
       <CommitSettingsCard />
diff --git a/apps/desktop/src/i18n/generated/catalog.json b/apps/desktop/src/i18n/generated/catalog.json
index be12b12..e0edae8 100644
--- a/apps/desktop/src/i18n/generated/catalog.json
+++ b/apps/desktop/src/i18n/generated/catalog.json
@@ -131,7 +131,7 @@
         },
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 182,
+          "line": 183,
           "column": 82
         },
         {
@@ -372,7 +372,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 99,
+          "line": 100,
           "column": 38
         }
       ]
@@ -401,7 +401,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 277,
+          "line": 279,
           "column": 26
         }
       ]
@@ -537,6 +537,23 @@
         }
       ]
     },
+    "13a494f82d7f26df": {
+      "source": "开启外部 API",
+      "kind": "text",
+      "placeholders": [],
+      "refs": [
+        {
+          "file": "features/settings/ExternalApiSettingsCard.tsx",
+          "line": 46,
+          "column": 20
+        },
+        {
+          "file": "features/settings/ExternalApiSettingsCard.tsx",
+          "line": 49,
+          "column": 24
+        }
+      ]
+    },
     "13a9ac7a68c5fd96": {
       "source": "CA 仅保存在本机，用于安全解析 Cursor 的 HTTPS 请求。",
       "kind": "text",
@@ -764,7 +781,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 281,
+          "line": 283,
           "column": 131
         }
       ]
@@ -790,17 +807,17 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 69,
+          "line": 70,
           "column": 42
         },
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 187,
+          "line": 188,
           "column": 22
         },
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 214,
+          "line": 215,
           "column": 58
         }
       ]
@@ -899,7 +916,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 254,
+          "line": 256,
           "column": 43
         }
       ]
@@ -923,7 +940,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 124,
+          "line": 125,
           "column": 15
         }
       ]
@@ -947,7 +964,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 304,
+          "line": 306,
           "column": 24
         }
       ]
@@ -1135,12 +1152,12 @@
         },
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 178,
+          "line": 179,
           "column": 81
         },
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 296,
+          "line": 298,
           "column": 22
         },
         {
@@ -1246,7 +1263,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 148,
+          "line": 149,
           "column": 15
         }
       ]
@@ -1396,7 +1413,7 @@
         },
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 239,
+          "line": 241,
           "column": 27
         }
       ]
@@ -1469,7 +1486,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 306,
+          "line": 308,
           "column": 42
         }
       ]
@@ -1534,7 +1551,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 288,
+          "line": 290,
           "column": 14
         }
       ]
@@ -1563,7 +1580,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 239,
+          "line": 241,
           "column": 39
         }
       ]
@@ -1630,12 +1647,12 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 246,
+          "line": 248,
           "column": 22
         },
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 252,
+          "line": 254,
           "column": 26
         }
       ]
@@ -1717,7 +1734,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 155,
+          "line": 156,
           "column": 66
         }
       ]
@@ -1729,7 +1746,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 272,
+          "line": 274,
           "column": 52
         }
       ]
@@ -2179,7 +2196,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 176,
+          "line": 177,
           "column": 26
         }
       ]
@@ -2302,7 +2319,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 232,
+          "line": 234,
           "column": 78
         }
       ]
@@ -2348,7 +2365,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 236,
+          "line": 238,
           "column": 21
         }
       ]
@@ -2446,6 +2463,18 @@
         }
       ]
     },
+    "5f600b307b4eb0fb": {
+      "source": "API 密钥",
+      "kind": "text",
+      "placeholders": [],
+      "refs": [
+        {
+          "file": "features/settings/ExternalApiSettingsCard.tsx",
+          "line": 52,
+          "column": 25
+        }
+      ]
+    },
     "5f8d556a9c47da3c": {
       "source": "已关闭开机启动",
       "kind": "text",
@@ -2649,7 +2678,7 @@
       "refs": [
         {
           "file": "shared/api.ts",
-          "line": 527,
+          "line": 532,
           "column": 43
         }
       ]
@@ -2776,7 +2805,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 99,
+          "line": 100,
           "column": 55
         }
       ]
@@ -2940,7 +2969,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 166,
+          "line": 167,
           "column": 16
         }
       ]
@@ -2964,7 +2993,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 264,
+          "line": 266,
           "column": 26
         }
       ]
@@ -2988,7 +3017,7 @@
       "refs": [
         {
           "file": "shared/api.ts",
-          "line": 522,
+          "line": 527,
           "column": 43
         }
       ]
@@ -3012,7 +3041,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 297,
+          "line": 299,
           "column": 23
         }
       ]
@@ -3029,6 +3058,18 @@
         }
       ]
     },
+    "7cc1cf151d967bda": {
+      "source": "允许本机应用使用密钥调用已配置的模型，包括插件模型。",
+      "kind": "text",
+      "placeholders": [],
+      "refs": [
+        {
+          "file": "features/settings/ExternalApiSettingsCard.tsx",
+          "line": 47,
+          "column": 19
+        }
+      ]
+    },
     "7cea2f3c46565d29": {
       "source": "OpenAI 额外参数",
       "kind": "text",
@@ -3067,7 +3108,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 142,
+          "line": 143,
           "column": 83
         }
       ]
@@ -3084,6 +3125,18 @@
         }
       ]
     },
+    "7ed9f96f513813a4": {
+      "source": "外部 API 设置已保存",
+      "kind": "text",
+      "placeholders": [],
+      "refs": [
+        {
+          "file": "features/settings/ExternalApiSettingsCard.tsx",
+          "line": 29,
+          "column": 15
+        }
+      ]
+    },
     "7f3c8312816fe26a": {
       "source": "刷新中…",
       "kind": "text",
@@ -3142,7 +3195,7 @@
       "refs": [
         {
           "file": "shared/api.ts",
-          "line": 456,
+          "line": 461,
           "column": 21
         }
       ]
@@ -3247,6 +3300,18 @@
         }
       ]
     },
+    "857d282a0213d785": {
+      "source": "外部 API",
+      "kind": "text",
+      "placeholders": [],
+      "refs": [
+        {
+          "file": "features/settings/ExternalApiSettingsCard.tsx",
+          "line": 40,
+          "column": 29
+        }
+      ]
+    },
     "864597982c308d72": {
       "source": "已开启静默启动",
       "kind": "text",
@@ -3387,7 +3452,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 235,
+          "line": 237,
           "column": 22
         }
       ]
@@ -3514,7 +3579,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 158,
+          "line": 159,
           "column": 7
         }
       ]
@@ -3670,6 +3735,18 @@
         }
       ]
     },
+    "99ac861433209a53": {
+      "source": "开启后，所有外部请求都必须提供此密钥。",
+      "kind": "text",
+      "placeholders": [],
+      "refs": [
+        {
+          "file": "features/settings/ExternalApiSettingsCard.tsx",
+          "line": 52,
+          "column": 44
+        }
+      ]
+    },
     "9a84733cc9ab1706": {
       "source": "资源详情",
       "kind": "text",
@@ -3838,7 +3915,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 243,
+          "line": 245,
           "column": 26
         }
       ]
@@ -3874,7 +3951,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 62,
+          "line": 63,
           "column": 34
         }
       ]
@@ -3971,6 +4048,11 @@
           "line": 213,
           "column": 22
         },
+        {
+          "file": "features/settings/ExternalApiSettingsCard.tsx",
+          "line": 41,
+          "column": 27
+        },
         {
           "file": "features/settings/PricingSettingsCard.tsx",
           "line": 92,
@@ -3983,7 +4065,7 @@
         },
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 179,
+          "line": 180,
           "column": 133
         },
         {
@@ -4377,6 +4459,18 @@
         }
       ]
     },
+    "b1968db970026087": {
+      "source": "基础地址",
+      "kind": "text",
+      "placeholders": [],
+      "refs": [
+        {
+          "file": "features/settings/ExternalApiSettingsCard.tsx",
+          "line": 57,
+          "column": 18
+        }
+      ]
+    },
     "b254ff315d861346": {
       "source": "请重试初始化",
       "kind": "text",
@@ -4495,7 +4589,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 155,
+          "line": 156,
           "column": 45
         }
       ]
@@ -4521,7 +4615,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 280,
+          "line": 282,
           "column": 22
         }
       ]
@@ -4679,7 +4773,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 281,
+          "line": 283,
           "column": 31
         }
       ]
@@ -4691,7 +4785,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 272,
+          "line": 274,
           "column": 40
         }
       ]
@@ -4977,12 +5071,12 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 164,
+          "line": 165,
           "column": 22
         },
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 170,
+          "line": 171,
           "column": 20
         }
       ]
@@ -4994,7 +5088,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 201,
+          "line": 202,
           "column": 21
         }
       ]
@@ -5030,7 +5124,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 157,
+          "line": 158,
           "column": 7
         }
       ]
@@ -5398,7 +5492,7 @@
         },
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 316,
+          "line": 318,
           "column": 30
         },
         {
@@ -5662,7 +5756,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 75,
+          "line": 76,
           "column": 17
         }
       ]
@@ -5756,7 +5850,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 161,
+          "line": 162,
           "column": 26
         }
       ]
@@ -5871,7 +5965,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 220,
+          "line": 221,
           "column": 16
         }
       ]
@@ -6032,7 +6126,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 247,
+          "line": 249,
           "column": 21
         }
       ]
@@ -6118,7 +6212,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 188,
+          "line": 189,
           "column": 21
         }
       ]
@@ -6316,7 +6410,7 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 307,
+          "line": 309,
           "column": 38
         }
       ]
@@ -6331,6 +6425,11 @@
           "line": 169,
           "column": 24
         },
+        {
+          "file": "features/settings/ExternalApiSettingsCard.tsx",
+          "line": 41,
+          "column": 15
+        },
         {
           "file": "features/settings/PricingSettingsCard.tsx",
           "line": 92,
@@ -6343,7 +6442,7 @@
         },
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 179,
+          "line": 180,
           "column": 121
         },
         {
@@ -6372,17 +6471,17 @@
       "refs": [
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 70,
+          "line": 71,
           "column": 46
         },
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 200,
+          "line": 201,
           "column": 22
         },
         {
           "file": "features/settings/SettingsPage.tsx",
-          "line": 215,
+          "line": 216,
           "column": 58
         }
       ]
diff --git a/apps/desktop/src/i18n/locales/en-US.json b/apps/desktop/src/i18n/locales/en-US.json
index 5f00647..d09d8d9 100644
--- a/apps/desktop/src/i18n/locales/en-US.json
+++ b/apps/desktop/src/i18n/locales/en-US.json
@@ -34,6 +34,7 @@
   "124be3f86f197802": "Token usage",
   "12ae77e6202d063e": "Custom Headers",
   "133340e53175128a": "Test all",
+  "13a494f82d7f26df": "Enable external API",
   "13a9ac7a68c5fd96": "The CA is stored only on this device and is used to securely inspect Cursor HTTPS requests.",
   "13b61c5f697b6700": "Cache hit rate",
   "146da2e2a991493e": "Fetching…",
@@ -163,6 +164,7 @@
   "5c55a67935af8f45": "All",
   "5c62e36c152dfc7c": "Plugin runtime initialized",
   "5d59857bf039cac9": "Cursor Assistant v{version}",
+  "5f600b307b4eb0fb": "API key",
   "5f8d556a9c47da3c": "Launch at login disabled",
   "5f9acfb945229062": "Are you sure you no longer want to see this ad?",
   "5fd2ec5a6e9b654c": "Total: {cost}",
@@ -205,10 +207,12 @@
   "7a3cec4ca715de80": "Call statistics",
   "7ba2d6728fe2531b": "Confirm clear",
   "7c10d97162c96dbd": "Validating the plugin runtime",
+  "7cc1cf151d967bda": "Allow local apps to call configured models, including plugin models, with an API key.",
   "7cea2f3c46565d29": "OpenAI extra parameters",
   "7d9f043f8f7ab45c": "Version {version} is available in Settings",
   "7e0891860c9e6374": "TAB service address is required",
   "7e7df68f2a82e09e": "Importing the same configuration again will not create duplicate models. Existing models are skipped automatically.",
+  "7ed9f96f513813a4": "External API settings saved",
   "7f3c8312816fe26a": "Refreshing…",
   "7f68ebad19ba6bcd": "Check for updates",
   "802b0faf0ceb513e": "{label}: {percent}% left",
@@ -221,6 +225,7 @@
   "842b9f11cdd96bda": "Launch at login",
   "843ac7e15a5047a7": "Confirm legacy model configuration import",
   "844b8cc8dff7c1d8": "Default",
+  "857d282a0213d785": "External API",
   "864597982c308d72": "Silent start enabled",
   "86de7c4ee8fa7689": "Sync models",
   "8716e1344b0daddb": "Cursor official",
@@ -252,6 +257,7 @@
   "9845c165151daee3": "Used",
   "9850ed41a5bfbb0c": "{count} selected",
   "997ec8201c2adeda": "Open terminal to install CA",
+  "99ac861433209a53": "All external requests must provide this key when enabled.",
   "9a84733cc9ab1706": "Resource details",
   "9b1b7ed518ee401d": "This will open the tutorial in your system browser. Continue?",
   "9b9bc9cd7c76406f": "Open authorization page",
@@ -298,6 +304,7 @@
   "affb73206cfa035d": "Expires: {time}",
   "b06325c5660f0c29": "Direct",
   "b16c3b2ecedd6fe1": "Cursor integration is active. Add a model configuration to use a BYOK model.",
+  "b1968db970026087": "Base URL",
   "b254ff315d861346": "Try initializing again",
   "b2617bf9ae663752": "Group settings",
   "b4411558b932266f": "Provider type",
diff --git a/apps/desktop/src/i18n/locales/pt-BR.json b/apps/desktop/src/i18n/locales/pt-BR.json
index 1c9a98a..1ed853a 100644
--- a/apps/desktop/src/i18n/locales/pt-BR.json
+++ b/apps/desktop/src/i18n/locales/pt-BR.json
@@ -34,6 +34,7 @@
   "124be3f86f197802": "Uso de tokens",
   "12ae77e6202d063e": "Cabeçalhos personalizados",
   "133340e53175128a": "Testar tudo",
+  "13a494f82d7f26df": "Ativar API externa",
   "13a9ac7a68c5fd96": "A CA é armazenada apenas neste dispositivo e é usada para inspecionar com segurança as requisições HTTPS do Cursor.",
   "13b61c5f697b6700": "Taxa de acerto de cache",
   "146da2e2a991493e": "Obtendo…",
@@ -163,6 +164,7 @@
   "5c55a67935af8f45": "Todos",
   "5c62e36c152dfc7c": "Runtime de plugins inicializado com sucesso",
   "5d59857bf039cac9": "Assistente Cursor v{version}",
+  "5f600b307b4eb0fb": "Chave da API",
   "5f8d556a9c47da3c": "Inicialização com o sistema desativada",
   "5f9acfb945229062": "Tem certeza de que não deseja mais ver este anúncio?",
   "5fd2ec5a6e9b654c": "Total: {cost}",
@@ -205,10 +207,12 @@
   "7a3cec4ca715de80": "Estatísticas de chamadas",
   "7ba2d6728fe2531b": "Confirmar limpeza",
   "7c10d97162c96dbd": "Validando o runtime de plugins",
+  "7cc1cf151d967bda": "Permite que aplicativos locais acessem os modelos configurados, incluindo modelos de plugins, com uma chave de API.",
   "7cea2f3c46565d29": "Parâmetros adicionais da OpenAI",
   "7d9f043f8f7ab45c": "Versão {version} disponível nas Configurações",
   "7e0891860c9e6374": "O endereço do serviço TAB é obrigatório",
   "7e7df68f2a82e09e": "Importar a mesma configuração novamente não criará modelos duplicados. Modelos existentes são ignorados automaticamente.",
+  "7ed9f96f513813a4": "Configurações da API externa salvas",
   "7f3c8312816fe26a": "Atualizando…",
   "7f68ebad19ba6bcd": "Verificar atualizações",
   "802b0faf0ceb513e": "{label}: {percent}% restante",
@@ -221,6 +225,7 @@
   "842b9f11cdd96bda": "Iniciar com o sistema",
   "843ac7e15a5047a7": "Confirmar importação da configuração legada de modelos",
   "844b8cc8dff7c1d8": "Padrão",
+  "857d282a0213d785": "API externa",
   "864597982c308d72": "Inicialização silenciosa ativada",
   "86de7c4ee8fa7689": "Sincronizar modelos",
   "8716e1344b0daddb": "Cursor Oficial",
@@ -252,6 +257,7 @@
   "9845c165151daee3": "Utilizado",
   "9850ed41a5bfbb0c": "{count} selecionados",
   "997ec8201c2adeda": "Abrir terminal para instalar CA",
+  "99ac861433209a53": "Todas as solicitações externas devem fornecer esta chave quando a API estiver ativada.",
   "9a84733cc9ab1706": "Detalhes do recurso",
   "9b1b7ed518ee401d": "O tutorial de uso será aberto no navegador padrão. Deseja continuar?",
   "9b9bc9cd7c76406f": "Abrir página de autorização",
@@ -298,6 +304,7 @@
   "affb73206cfa035d": "Expira em: {time}",
   "b06325c5660f0c29": "Conexão direta",
   "b16c3b2ecedd6fe1": "A integração com o Cursor está ativa. Adicione uma configuração de modelo para usar modelos BYOK.",
+  "b1968db970026087": "URL base",
   "b254ff315d861346": "Tente inicializar novamente",
   "b2617bf9ae663752": "Configurações do grupo",
   "b4411558b932266f": "Tipo de provedor",
diff --git a/apps/desktop/src/i18n/locales/zh-CN.json b/apps/desktop/src/i18n/locales/zh-CN.json
index 36c9f67..2375022 100644
--- a/apps/desktop/src/i18n/locales/zh-CN.json
+++ b/apps/desktop/src/i18n/locales/zh-CN.json
@@ -34,6 +34,7 @@
   "124be3f86f197802": "Token 消耗",
   "12ae77e6202d063e": "自定义 Headers",
   "133340e53175128a": "一键测试",
+  "13a494f82d7f26df": "开启外部 API",
   "13a9ac7a68c5fd96": "CA 仅保存在本机，用于安全解析 Cursor 的 HTTPS 请求。",
   "13b61c5f697b6700": "缓存命中率",
   "146da2e2a991493e": "获取中…",
@@ -163,6 +164,7 @@
   "5c55a67935af8f45": "全部",
   "5c62e36c152dfc7c": "插件运行时初始化完成",
   "5d59857bf039cac9": "Cursor 助手 v{version}",
+  "5f600b307b4eb0fb": "API 密钥",
   "5f8d556a9c47da3c": "已关闭开机启动",
   "5f9acfb945229062": "你确认不想再看到此广告吗？",
   "5fd2ec5a6e9b654c": "合计：{cost}",
@@ -205,10 +207,12 @@
   "7a3cec4ca715de80": "调用统计",
   "7ba2d6728fe2531b": "确认清理",
   "7c10d97162c96dbd": "正在验证插件运行时",
+  "7cc1cf151d967bda": "允许本机应用使用密钥调用已配置的模型，包括插件模型。",
   "7cea2f3c46565d29": "OpenAI 额外参数",
   "7d9f043f8f7ab45c": "发现新版本 {version}，可在设置中安装",
   "7e0891860c9e6374": "TAB 服务地址不能为空",
   "7e7df68f2a82e09e": "重复导入相同配置不会创建重复模型；已经存在的模型会自动跳过。",
+  "7ed9f96f513813a4": "外部 API 设置已保存",
   "7f3c8312816fe26a": "刷新中…",
   "7f68ebad19ba6bcd": "检查更新",
   "802b0faf0ceb513e": "{label} 剩余 {percent}%",
@@ -221,6 +225,7 @@
   "842b9f11cdd96bda": "开机启动",
   "843ac7e15a5047a7": "确认导入旧版模型配置",
   "844b8cc8dff7c1d8": "默认",
+  "857d282a0213d785": "外部 API",
   "864597982c308d72": "已开启静默启动",
   "86de7c4ee8fa7689": "同步模型",
   "8716e1344b0daddb": "Cursor 官方",
@@ -252,6 +257,7 @@
   "9845c165151daee3": "已使用",
   "9850ed41a5bfbb0c": "已选 {count} 项",
   "997ec8201c2adeda": "打开终端安装 CA",
+  "99ac861433209a53": "开启后，所有外部请求都必须提供此密钥。",
   "9a84733cc9ab1706": "资源详情",
   "9b1b7ed518ee401d": "将在系统浏览器中打开使用教程，是否继续？",
   "9b9bc9cd7c76406f": "打开授权网页",
@@ -298,6 +304,7 @@
   "affb73206cfa035d": "到期时间：{time}",
   "b06325c5660f0c29": "直连",
   "b16c3b2ecedd6fe1": "Cursor 接管已生效；添加模型配置后即可使用 BYOK 模型。",
+  "b1968db970026087": "基础地址",
   "b254ff315d861346": "请重试初始化",
   "b2617bf9ae663752": "分组设置",
   "b4411558b932266f": "上游类型",
diff --git a/apps/desktop/src/shared/api.ts b/apps/desktop/src/shared/api.ts
index 0c70886..bb1f36b 100644
--- a/apps/desktop/src/shared/api.ts
+++ b/apps/desktop/src/shared/api.ts
@@ -113,6 +113,11 @@ export interface PortSettings {
   service_port: number;
 }
 
+export interface ExternalApiSettings {
+  enabled: boolean;
+  api_key: string;
+}
+
 export interface StatisticsStorage {
   call_count: number;
   trace_count: number;
@@ -541,6 +546,8 @@ export const api = {
   setObservability: (detailed: boolean) => request<{ detailed: boolean }>("/settings/observability", { method: "PUT", body: JSON.stringify({ detailed }) }),
   ports: () => request<PortSettings>("/settings/ports"),
   setPorts: (settings: PortSettings) => request<PortSettings>("/settings/ports", { method: "PUT", body: JSON.stringify(settings) }),
+  externalApiSettings: () => request<ExternalApiSettings>("/settings/external-api"),
+  setExternalApiSettings: (settings: ExternalApiSettings) => request<ExternalApiSettings>("/settings/external-api", { method: "PUT", body: JSON.stringify(settings) }),
   statisticsStorage: () => request<StatisticsStorage>("/settings/storage/statistics"),
   clearStatisticsStorage: (scope: StatisticsStorageScope) => request<StatisticsStorage>("/settings/storage/statistics", { method: "DELETE", body: JSON.stringify({ scope }) }),
   proxySettings: () => request<ProxySettings>("/settings/proxy"),
diff --git a/server/src/api/byok/direct.rs b/server/src/api/byok/direct.rs
new file mode 100644
index 0000000..b0e3d43
--- /dev/null
+++ b/server/src/api/byok/direct.rs
@@ -0,0 +1,379 @@
+//! Forwards matching HTTP protocols without projecting provider messages.
+use std::time::Duration;
+
+use async_stream::try_stream;
+use axum::{
+    body::Body,
+    http::{header, HeaderMap, StatusCode},
+    response::Response,
+};
+use bytes::Bytes;
+use eventsource_stream::Eventsource;
+use futures_util::StreamExt;
+use serde_json::Value;
+use tokio_stream::wrappers::ReceiverStream;
+
+use crate::{
+    model::{ModelConfig, NewLlmCall, Usage},
+    network::NetworkClients,
+    provider::{custom_headers, CallRecorder, FinishReason},
+    store::Store,
+    Error, Result,
+};
+
+use super::protocol::Protocol;
+
+#[derive(Clone)]
+pub struct NativeForwarder {
+    store: Store,
+    clients: NetworkClients,
+    request_timeout: Duration,
+    stream_idle_timeout: Duration,
+}
+
+impl NativeForwarder {
+    pub fn new(
+        store: Store,
+        clients: NetworkClients,
+        request_timeout: Duration,
+        stream_idle_timeout: Duration,
+    ) -> Self {
+        Self {
+            store,
+            clients,
+            request_timeout,
+            stream_idle_timeout,
+        }
+    }
+
+    pub(super) async fn forward(
+        &self,
+        protocol: Protocol,
+        incoming_headers: &HeaderMap,
+        mut body: Value,
+        model: &ModelConfig,
+    ) -> Result<Response> {
+        let call_id = format!("external-api:{}", uuid::Uuid::new_v4());
+        let request_url = model.request_url()?;
+        let new_call = NewLlmCall {
+            call_id: call_id.clone(),
+            run_id: call_id.clone(),
+            conversation_id: call_id.clone(),
+            provider_call_index: 0,
+            model_hash: model.model_hash.clone(),
+            provider_type: model.provider_type(),
+            provider_url: request_url.clone(),
+            request_type: model.provider_type(),
+            request_url: request_url.clone(),
+            model_id: model.model_id.clone(),
+            display_name: model.display_name.clone(),
+            reasoning_effort: model.reasoning_effort.clone(),
+            fast: false,
+            message_count: body
+                .get("messages")
+                .or_else(|| body.get("input"))
+                .and_then(Value::as_array)
+                .map_or(1, Vec::len),
+            tool_count: body
+                .get("tools")
+                .and_then(Value::as_array)
+                .map_or(0, Vec::len),
+            detailed: false,
+        };
+        body["model"] = Value::String(model.model_id.clone());
+        let mut upstream_headers = HeaderMap::new();
+        for (name, value) in incoming_headers {
+            if !matches!(
+                name.as_str(),
+                "authorization"
+                    | "x-api-key"
+                    | "host"
+                    | "content-length"
+                    | "content-type"
+                    | "connection"
+                    | "transfer-encoding"
+                    | "accept-encoding"
+                    | "cookie"
+                    | "proxy-authorization"
+                    | "proxy-authenticate"
+                    | "te"
+                    | "trailer"
+                    | "upgrade"
+            ) {
+                upstream_headers.append(name, value.clone());
+            }
+        }
+        if model.custom_headers_enabled {
+            upstream_headers.extend(custom_headers(&model.custom_headers, &call_id)?);
+        }
+        match protocol {
+            Protocol::Messages => {
+                upstream_headers.insert(
+                    "x-api-key",
+                    model.api_key.parse().map_err(|error| {
+                        Error::Config(format!("invalid API key header: {error}"))
+                    })?,
+                );
+                if !upstream_headers.contains_key("anthropic-version") {
+                    upstream_headers.insert("anthropic-version", "2023-06-01".parse().unwrap());
+                }
+            }
+            Protocol::Chat | Protocol::Responses => {
+                upstream_headers.insert(
+                    header::AUTHORIZATION,
+                    format!("Bearer {}", model.api_key)
+                        .parse()
+                        .map_err(|error| {
+                            Error::Config(format!("invalid API key header: {error}"))
+                        })?,
+                );
+            }
+        }
+        let logged_headers = upstream_headers
+            .iter()
+            .filter(|(name, _)| !crate::model::is_sensitive_header(name.as_str()))
+            .filter_map(|(name, value)| {
+                value
+                    .to_str()
+                    .ok()
+                    .map(|value| (name.as_str().to_owned(), Value::String(value.to_owned())))
+            })
+            .collect::<serde_json::Map<_, _>>();
+        let client = self.clients.provider_client(self.request_timeout).await?;
+        let recorder = CallRecorder::start(self.store.clone(), new_call).await?;
+        recorder
+            .request(Value::Object(logged_headers), &body)
+            .await?;
+        let response = match client
+            .post(&request_url)
+            .headers(upstream_headers)
+            .json(&body)
+            .send()
+            .await
+        {
+            Ok(response) => response,
+            Err(error) => {
+                let error = Error::Http(error);
+                recorder.failed(&error).await?;
+                return Err(error);
+            }
+        };
+        let status = response.status();
+        recorder.response_headers(status.as_u16()).await?;
+        let headers = response.headers().clone();
+        let stream = body.get("stream").and_then(Value::as_bool).unwrap_or(false);
+        if stream && status.is_success() {
+            Ok(self.stream_response(protocol, response, recorder, status, &headers))
+        } else {
+            let bytes = match response.bytes().await {
+                Ok(bytes) => bytes,
+                Err(error) => {
+                    let error = Error::Http(error);
+                    recorder.failed(&error).await?;
+                    return Err(error);
+                }
+            };
+            recorder.response_chunk(&bytes).await?;
+            if status.is_success() {
+                if let Ok(value) = serde_json::from_slice::<Value>(&bytes) {
+                    let summary = NativeSummary::from_value(protocol, &value);
+                    if let Some(usage) = summary.usage {
+                        recorder.usage(usage).await?;
+                    }
+                    if let Some(message) = summary.failure {
+                        recorder.failed(&Error::Provider(message)).await?;
+                    } else {
+                        recorder
+                            .completed(summary.finish.unwrap_or(FinishReason::Stop))
+                            .await?;
+                    }
+                } else {
+                    recorder.completed(FinishReason::Stop).await?;
+                }
+            } else {
+                recorder
+                    .failed(&Error::Provider(format!("upstream returned {status}")))
+                    .await?;
+            }
+            Ok(build_response(status, &headers, Body::from(bytes)))
+        }
+    }
+
+    fn stream_response(
+        &self,
+        protocol: Protocol,
+        response: reqwest::Response,
+        recorder: CallRecorder,
+        status: StatusCode,
+        headers: &HeaderMap,
+    ) -> Response {
+        let idle_timeout = self.stream_idle_timeout;
+        let output = try_stream! {
+            let _cancel = recorder.cancel_on_drop();
+            let (sender, receiver) = tokio::sync::mpsc::channel::<Bytes>(8);
+            let observer = tokio::spawn(observe_events(protocol, receiver));
+            let mut upstream = response.bytes_stream();
+            loop {
+                let next = tokio::time::timeout(idle_timeout, upstream.next()).await;
+                let chunk = match next {
+                    Ok(Some(Ok(chunk))) => chunk,
+                    Ok(None) => break,
+                    Ok(Some(Err(error))) => {
+                        let error = Error::Http(error);
+                        recorder.failed(&error).await?;
+                        Err::<Bytes, Error>(error)?
+                    }
+                    Err(_) => {
+                        let error = Error::Provider("native upstream stream idle timeout".into());
+                        recorder.failed(&error).await?;
+                        Err::<Bytes, Error>(error)?
+                    }
+                };
+                recorder.response_chunk(&chunk).await?;
+                let _ = sender.send(chunk.clone()).await;
+                yield chunk;
+            }
+            drop(sender);
+            if let Ok(summary) = observer.await {
+                if let Some(usage) = summary.usage { recorder.usage(usage).await?; }
+                if let Some(message) = summary.failure {
+                    recorder.failed(&Error::Provider(message)).await?;
+                } else {
+                    recorder.completed(summary.finish.unwrap_or(FinishReason::Stop)).await?;
+                }
+            } else {
+                recorder.completed(FinishReason::Stop).await?;
+            }
+        };
+        let output = output.map(|result: Result<Bytes>| result);
+        build_response(status, headers, Body::from_stream(output))
+    }
+}
+
+fn build_response(status: StatusCode, headers: &HeaderMap, body: Body) -> Response {
+    let mut response = Response::new(body);
+    *response.status_mut() = status;
+    for (name, value) in headers {
+        if !matches!(
+            name.as_str(),
+            "content-length" | "content-encoding" | "transfer-encoding" | "connection"
+        ) {
+            response.headers_mut().append(name, value.clone());
+        }
+    }
+    response
+}
+
+#[derive(Default)]
+struct NativeSummary {
+    usage: Option<Usage>,
+    finish: Option<FinishReason>,
+    failure: Option<String>,
+}
+
+impl NativeSummary {
+    fn from_value(protocol: Protocol, value: &Value) -> Self {
+        let mut summary = Self::default();
+        summary.observe(protocol, value);
+        summary
+    }
+
+    fn observe(&mut self, protocol: Protocol, value: &Value) {
+        if matches!(
+            value.get("type").and_then(Value::as_str),
+            Some("error" | "response.failed")
+        ) || value.get("error").is_some_and(|error| !error.is_null())
+        {
+            self.failure = Some(
+                value
+                    .pointer("/error/message")
+                    .or_else(|| value.pointer("/response/error/message"))
+                    .or_else(|| value.get("message"))
+                    .and_then(Value::as_str)
+                    .unwrap_or("upstream error event")
+                    .to_owned(),
+            );
+        }
+        let usage = match protocol {
+            Protocol::Chat => value.get("usage"),
+            Protocol::Responses => value
+                .pointer("/response/usage")
+                .or_else(|| value.get("usage")),
+            Protocol::Messages => value
+                .pointer("/message/usage")
+                .or_else(|| value.get("usage")),
+        }
+        .filter(|usage| !usage.is_null())
+        .map(|usage| crate::provider::native_usage(protocol.provider_type(), usage));
+        if let Some(usage) = usage {
+            let current = self.usage.get_or_insert_default();
+            for (target, incoming) in [
+                (&mut current.input_tokens, usage.input_tokens),
+                (
+                    &mut current.context_input_tokens,
+                    usage.context_input_tokens,
+                ),
+                (&mut current.output_tokens, usage.output_tokens),
+                (&mut current.total_tokens, usage.total_tokens),
+                (&mut current.cache_read_tokens, usage.cache_read_tokens),
+                (&mut current.cache_write_tokens, usage.cache_write_tokens),
+                (&mut current.reasoning_tokens, usage.reasoning_tokens),
+            ] {
+                if incoming.is_some() {
+                    *target = incoming;
+                }
+            }
+        }
+        let reason = match protocol {
+            Protocol::Chat => value
+                .pointer("/choices/0/finish_reason")
+                .and_then(Value::as_str),
+            Protocol::Responses => value
+                .pointer("/response/incomplete_details/reason")
+                .and_then(Value::as_str),
+            Protocol::Messages => value
+                .pointer("/delta/stop_reason")
+                .or_else(|| value.get("stop_reason"))
+                .and_then(Value::as_str),
+        };
+        self.finish = match reason {
+            Some("tool_calls" | "tool_use") => Some(FinishReason::ToolUse),
+            Some("length" | "max_tokens" | "max_output_tokens") => Some(FinishReason::Length),
+            Some(_) => Some(FinishReason::Stop),
+            None => self.finish,
+        };
+        if matches!(protocol, Protocol::Responses)
+            && (value.pointer("/item/type").and_then(Value::as_str) == Some("function_call")
+                || value
+                    .pointer("/response/output")
+                    .and_then(Value::as_array)
+                    .is_some_and(|items| {
+                        items.iter().any(|item| {
+                            item.get("type").and_then(Value::as_str) == Some("function_call")
+                        })
+                    }))
+        {
+            self.finish = Some(FinishReason::ToolUse);
+        }
+    }
+}
+
+async fn observe_events(
+    protocol: Protocol,
+    receiver: tokio::sync::mpsc::Receiver<Bytes>,
+) -> NativeSummary {
+    let source = ReceiverStream::new(receiver)
+        .map(Ok::<_, Error>)
+        .eventsource();
+    futures_util::pin_mut!(source);
+    let mut summary = NativeSummary::default();
+    while let Some(event) = source.next().await {
+        let Ok(event) = event else {
+            break;
+        };
+        if let Ok(value) = serde_json::from_str::<Value>(&event.data) {
+            summary.observe(protocol, &value);
+        }
+    }
+    summary
+}
diff --git a/server/src/api/byok/mod.rs b/server/src/api/byok/mod.rs
new file mode 100644
index 0000000..6a376fd
--- /dev/null
+++ b/server/src/api/byok/mod.rs
@@ -0,0 +1,201 @@
+//! External OpenAI and Anthropic compatible API.
+mod direct;
+mod models;
+mod output;
+mod protocol;
+
+use std::sync::Arc;
+
+use axum::{
+    extract::State,
+    http::{header, HeaderMap, StatusCode},
+    response::{IntoResponse, Response},
+    routing::{get, post},
+    Json, Router,
+};
+use serde_json::{json, Value};
+use tokio_util::sync::CancellationToken;
+
+use crate::{
+    model::ModelInvocation, plugin::PluginRegistry, provider::Provider, store::Store, Error,
+};
+
+use self::protocol::Protocol;
+pub use direct::NativeForwarder;
+
+#[derive(Clone)]
+struct ApiState {
+    store: Store,
+    plugins: PluginRegistry,
+    provider: Arc<dyn Provider>,
+    native: Option<NativeForwarder>,
+}
+
+pub fn router(
+    store: Store,
+    plugins: PluginRegistry,
+    provider: Arc<dyn Provider>,
+    native: Option<NativeForwarder>,
+) -> Router {
+    Router::new()
+        .route("/byok/v1/models", get(list_models))
+        .route("/byok/v1/chat/completions", post(chat))
+        .route("/byok/v1/responses", post(responses))
+        .route("/byok/v1/messages", post(messages))
+        .with_state(ApiState {
+            store,
+            plugins,
+            provider,
+            native,
+        })
+}
+
+fn api_error(status: StatusCode, message: impl std::fmt::Display) -> Response {
+    (status, Json(json!({"error":{"message":message.to_string(),"type":if status.is_client_error() { "invalid_request_error" } else { "server_error" }}}))).into_response()
+}
+
+async fn authorized(
+    state: &ApiState,
+    headers: &HeaderMap,
+) -> std::result::Result<(), Box<Response>> {
+    let settings = state
+        .store
+        .external_api_settings()
+        .await
+        .map_err(|error| Box::new(api_error(StatusCode::INTERNAL_SERVER_ERROR, error)))?;
+    if !settings.enabled {
+        return Err(Box::new(api_error(
+            StatusCode::FORBIDDEN,
+            "external API is disabled",
+        )));
+    }
+    let supplied = headers
+        .get(header::AUTHORIZATION)
+        .and_then(|value| value.to_str().ok())
+        .and_then(|value| value.strip_prefix("Bearer "))
+        .or_else(|| {
+            headers
+                .get("x-api-key")
+                .and_then(|value| value.to_str().ok())
+        })
+        .unwrap_or_default();
+    if supplied.is_empty() || !constant_time_eq(supplied.as_bytes(), settings.api_key.as_bytes()) {
+        return Err(Box::new(api_error(
+            StatusCode::UNAUTHORIZED,
+            "invalid API key",
+        )));
+    }
+    Ok(())
+}
+
+fn constant_time_eq(left: &[u8], right: &[u8]) -> bool {
+    if left.len() != right.len() {
+        return false;
+    }
+    let difference = left
+        .iter()
+        .zip(right)
+        .fold(0_u8, |difference, (left, right)| {
+            difference | (left ^ right)
+        });
+    difference == 0
+}
+
+async fn list_models(State(state): State<ApiState>, headers: HeaderMap) -> Response {
+    if let Err(error) = authorized(&state, &headers).await {
+        return *error;
+    }
+    match models::list(&state.store, &state.plugins).await {
+        Ok(models) => Json(models::response(&models)).into_response(),
+        Err(error) => api_error(StatusCode::CONFLICT, error),
+    }
+}
+
+async fn chat(
+    State(state): State<ApiState>,
+    headers: HeaderMap,
+    Json(body): Json<Value>,
+) -> Response {
+    generate(state, headers, body, Protocol::Chat).await
+}
+
+async fn responses(
+    State(state): State<ApiState>,
+    headers: HeaderMap,
+    Json(body): Json<Value>,
+) -> Response {
+    generate(state, headers, body, Protocol::Responses).await
+}
+
+async fn messages(
+    State(state): State<ApiState>,
+    headers: HeaderMap,
+    Json(body): Json<Value>,
+) -> Response {
+    generate(state, headers, body, Protocol::Messages).await
+}
+
+async fn generate(
+    state: ApiState,
+    headers: HeaderMap,
+    body: Value,
+    protocol: Protocol,
+) -> Response {
+    if let Err(error) = authorized(&state, &headers).await {
+        return *error;
+    }
+    let Some(public_model_id) = body
+        .get("model")
+        .and_then(Value::as_str)
+        .filter(|id| !id.is_empty())
+    else {
+        return api_error(StatusCode::BAD_REQUEST, "model is required");
+    };
+    let models = match models::list(&state.store, &state.plugins).await {
+        Ok(models) => models,
+        Err(error) => return api_error(StatusCode::CONFLICT, error),
+    };
+    let Some(model) = models
+        .iter()
+        .find(|model| model.public_id == public_model_id)
+    else {
+        return api_error(StatusCode::NOT_FOUND, "model not found");
+    };
+    if let Some(native) = &state.native {
+        match state.store.model(&model.internal_id).await {
+            Ok(Some(config)) if protocol.provider_type() == config.provider_type() => {
+                return match native.forward(protocol, &headers, body, &config).await {
+                    Ok(response) => response,
+                    Err(error) => api_error(StatusCode::BAD_GATEWAY, error),
+                };
+            }
+            Ok(_) => {}
+            Err(error) => return api_error(StatusCode::INTERNAL_SERVER_ERROR, error),
+        }
+    }
+    let parsed = match protocol::parse(protocol, &body) {
+        Ok(parsed) => parsed,
+        Err(error) => return api_error(StatusCode::BAD_REQUEST, error),
+    };
+    let id = format!("external-api:{}", uuid::Uuid::new_v4());
+    let mut request = parsed.request;
+    request.model.model_id = model.internal_id.clone();
+    let invocation = ModelInvocation {
+        call_id: id.clone(),
+        run_id: id.clone(),
+        conversation_id: id.clone(),
+        provider_call_index: 0,
+        request,
+    };
+    let cancellation = CancellationToken::new();
+    let stream = state.provider.stream(invocation, cancellation.clone());
+    if parsed.stream {
+        output::streamed(protocol, stream, cancellation, id, parsed.public_model_id)
+    } else {
+        match output::complete(protocol, stream, &id, &parsed.public_model_id).await {
+            Ok(response) => response.into_response(),
+            Err(Error::Protocol(message)) => api_error(StatusCode::BAD_REQUEST, message),
+            Err(error) => api_error(StatusCode::BAD_GATEWAY, error),
+        }
+    }
+}
diff --git a/server/src/api/byok/models.rs b/server/src/api/byok/models.rs
new file mode 100644
index 0000000..5eb2e07
--- /dev/null
+++ b/server/src/api/byok/models.rs
@@ -0,0 +1,66 @@
+use std::collections::HashSet;
+
+use serde_json::{json, Value};
+
+use crate::{plugin::PluginRegistry, store::Store, Result};
+
+#[derive(Clone)]
+pub(super) struct ListedModel {
+    pub public_id: String,
+    pub internal_id: String,
+    pub display_name: String,
+}
+
+pub(super) async fn list(store: &Store, plugins: &PluginRegistry) -> Result<Vec<ListedModel>> {
+    let mut models = Vec::new();
+    let mut ids = HashSet::new();
+    let mut configured = store.models().await?;
+    configured.sort_by(|left, right| {
+        left.sort_order
+            .cmp(&right.sort_order)
+            .then_with(|| left.display_name.cmp(&right.display_name))
+            .then_with(|| left.model_hash.cmp(&right.model_hash))
+    });
+    for model in configured {
+        let group = model
+            .group_name
+            .as_deref()
+            .filter(|value| !value.trim().is_empty())
+            .map(str::to_owned)
+            .unwrap_or_else(|| {
+                url::Url::parse(&model.base_url)
+                    .ok()
+                    .and_then(|url| url.host_str().map(str::to_owned))
+                    .unwrap_or_else(|| model.base_url.clone())
+            });
+        let public_id = format!("{group}/{}", model.model_id);
+        if ids.insert(public_id.clone()) {
+            models.push(ListedModel {
+                public_id,
+                internal_id: model.model_hash,
+                display_name: model.display_name,
+            });
+        }
+    }
+    for model in plugins.configured_models().await {
+        let public_id = format!(
+            "plugin:{}:{}/{}",
+            model.plugin_id, model.provider_id, model.model_id
+        );
+        if ids.insert(public_id.clone()) {
+            models.push(ListedModel {
+                public_id,
+                internal_id: model.id,
+                display_name: model.display_name,
+            });
+        }
+    }
+    Ok(models)
+}
+
+pub(super) fn response(models: &[ListedModel]) -> Value {
+    json!({"object":"list","data":models.iter().map(|model| json!({
+        "id":model.public_id,"object":"model","created":0,"owned_by":"cursor-byok",
+        "name":model.display_name
+    })).collect::<Vec<_>>()})
+}
diff --git a/server/src/api/byok/output.rs b/server/src/api/byok/output.rs
new file mode 100644
index 0000000..13c0cbf
--- /dev/null
+++ b/server/src/api/byok/output.rs
@@ -0,0 +1,444 @@
+use std::{
+    collections::{BTreeMap, HashSet},
+    convert::Infallible,
+};
+
+use axum::{
+    response::{
+        sse::{Event, KeepAlive, Sse},
+        IntoResponse, Response,
+    },
+    Json,
+};
+use futures_util::StreamExt;
+use serde_json::{json, Value};
+use tokio_util::sync::CancellationToken;
+
+use crate::{
+    model::Usage,
+    provider::{FinishReason, ModelEvent, ProviderStream},
+    Error, Result,
+};
+
+use super::protocol::Protocol;
+
+#[derive(Default)]
+struct ToolOutput {
+    id: String,
+    name: String,
+    arguments: String,
+}
+
+#[derive(Default)]
+struct Output {
+    text: String,
+    thinking: String,
+    tools: BTreeMap<usize, ToolOutput>,
+    usage: Option<Usage>,
+    finish: Option<FinishReason>,
+}
+
+impl Output {
+    fn update(&mut self, event: &ModelEvent) {
+        match event {
+            ModelEvent::TextDelta(delta) => self.text.push_str(delta),
+            ModelEvent::ThinkingDelta(delta) => self.thinking.push_str(delta),
+            ModelEvent::ToolCallStart {
+                index,
+                call_id,
+                name,
+            } => {
+                self.tools.insert(
+                    *index,
+                    ToolOutput {
+                        id: call_id.clone(),
+                        name: name.clone(),
+                        arguments: String::new(),
+                    },
+                );
+            }
+            ModelEvent::ToolCallArgumentsDelta { index, delta } => {
+                if let Some(tool) = self.tools.get_mut(index) {
+                    tool.arguments.push_str(delta);
+                }
+            }
+            ModelEvent::Usage(usage) => self.usage = Some(*usage),
+            ModelEvent::Done(reason) => self.finish = Some(*reason),
+            _ => {}
+        }
+    }
+
+    fn json(&self, protocol: Protocol, id: &str, model: &str) -> Value {
+        let usage = self.usage_json(protocol);
+        let finish = match self.finish.unwrap_or(FinishReason::Stop) {
+            FinishReason::Stop => "stop",
+            FinishReason::Length => "length",
+            FinishReason::ToolUse => "tool_calls",
+        };
+        match protocol {
+            Protocol::Chat => json!({"id":id,"object":"chat.completion","created":0,"model":model,
+                "choices":[{"index":0,"message":{"role":"assistant","content":self.text,
+                    "tool_calls":self.tools.values().map(|tool| json!({"id":tool.id,"type":"function",
+                        "function":{"name":tool.name,"arguments":tool.arguments}})).collect::<Vec<_>>()},"finish_reason":finish}],
+                "usage":usage}),
+            Protocol::Responses => {
+                let mut items = Vec::new();
+                if !self.text.is_empty() {
+                    items.push(json!({"id":format!("msg_{id}"),"type":"message","status":"completed",
+                    "role":"assistant","content":[{"type":"output_text","text":self.text,"annotations":[]}]}));
+                }
+                items.extend(self.tools.values().map(|tool| json!({"type":"function_call","id":format!("fc_{}",tool.id),
+                    "call_id":tool.id,"name":tool.name,"arguments":tool.arguments,"status":"completed"})));
+                json!({"id":id,"object":"response","created_at":0,"status":"completed","model":model,
+                    "output":items,"output_text":self.text,
+                    "usage":usage})
+            }
+            Protocol::Messages => {
+                let mut content = Vec::new();
+                if !self.text.is_empty() {
+                    content.push(json!({"type":"text","text":self.text}));
+                }
+                content.extend(self.tools.values().map(|tool| {
+                    json!({"type":"tool_use","id":tool.id,"name":tool.name,
+                    "input":serde_json::from_str::<Value>(&tool.arguments).unwrap_or(json!({}))})
+                }));
+                json!({"id":id,"type":"message","role":"assistant","model":model,"content":content,
+                    "stop_reason":if self.tools.is_empty() { match self.finish { Some(FinishReason::Length) => "max_tokens", _ => "end_turn" } } else { "tool_use" },
+                    "stop_sequence":null,"usage":usage})
+            }
+        }
+    }
+
+    fn usage_json(&self, protocol: Protocol) -> Value {
+        let usage = self.usage.unwrap_or_default();
+        let input = usage
+            .context_input_tokens
+            .or(usage.input_tokens)
+            .unwrap_or(0);
+        let output = usage.output_tokens.unwrap_or(0);
+        match protocol {
+            Protocol::Chat => {
+                let mut value = json!({"prompt_tokens":input,"completion_tokens":output,
+                    "total_tokens":usage.total_tokens.unwrap_or(input.saturating_add(output))});
+                if let Some(cached) = usage.cache_read_tokens {
+                    value["prompt_tokens_details"] = json!({"cached_tokens":cached});
+                }
+                if let Some(reasoning) = usage.reasoning_tokens {
+                    value["completion_tokens_details"] = json!({"reasoning_tokens":reasoning});
+                }
+                value
+            }
+            Protocol::Responses => {
+                let mut value = json!({"input_tokens":input,"output_tokens":output,
+                    "total_tokens":usage.total_tokens.unwrap_or(input.saturating_add(output))});
+                if let Some(cached) = usage.cache_read_tokens {
+                    value["input_tokens_details"] = json!({"cached_tokens":cached});
+                }
+                if let Some(reasoning) = usage.reasoning_tokens {
+                    value["output_tokens_details"] = json!({"reasoning_tokens":reasoning});
+                }
+                value
+            }
+            Protocol::Messages => {
+                let uncached =
+                    usage
+                        .context_input_tokens
+                        .map_or(usage.input_tokens.unwrap_or(0), |total| {
+                            total
+                                .saturating_sub(usage.cache_read_tokens.unwrap_or(0))
+                                .saturating_sub(usage.cache_write_tokens.unwrap_or(0))
+                        });
+                let mut value = json!({"input_tokens":uncached,"output_tokens":output});
+                if let Some(cached) = usage.cache_read_tokens {
+                    value["cache_read_input_tokens"] = json!(cached);
+                }
+                if let Some(written) = usage.cache_write_tokens {
+                    value["cache_creation_input_tokens"] = json!(written);
+                }
+                value
+            }
+        }
+    }
+}
+
+pub(super) async fn complete(
+    protocol: Protocol,
+    mut stream: ProviderStream,
+    id: &str,
+    model: &str,
+) -> Result<Json<Value>> {
+    let mut output = Output::default();
+    while let Some(event) = stream.next().await {
+        output.update(&event?);
+    }
+    if output.finish.is_none() {
+        return Err(Error::Provider(
+            "model stream ended without completion".into(),
+        ));
+    }
+    Ok(Json(output.json(protocol, id, model)))
+}
+
+struct CancelOnDrop(CancellationToken);
+impl Drop for CancelOnDrop {
+    fn drop(&mut self) {
+        self.0.cancel();
+    }
+}
+
+pub(super) fn streamed(
+    protocol: Protocol,
+    mut provider: ProviderStream,
+    cancellation: CancellationToken,
+    id: String,
+    model: String,
+) -> Response {
+    let events = async_stream::stream! {
+        let _cancel = CancelOnDrop(cancellation);
+        let mut output = Output::default();
+        if matches!(protocol, Protocol::Chat) {
+            yield Ok::<Event, Infallible>(Event::default().data(chat_chunk(&id, &model, json!({"role":"assistant"}), Value::Null).to_string()));
+        } else if matches!(protocol, Protocol::Responses) {
+            yield Ok(Event::default().event("response.created").data(json!({"type":"response.created","response":{"id":id,"status":"in_progress","model":model}}).to_string()));
+            yield Ok(Event::default().event("response.in_progress").data(json!({"type":"response.in_progress","response":{"id":id,"status":"in_progress","model":model}}).to_string()));
+        } else {
+            yield Ok(Event::default().event("message_start").data(json!({"type":"message_start","message":{"id":id,"type":"message","role":"assistant","model":model,"content":[],"usage":{"input_tokens":0,"output_tokens":0}}}).to_string()));
+        }
+        let mut text_started = false;
+        let mut text_closed = false;
+        let mut closed_tools = HashSet::new();
+        while let Some(result) = provider.next().await {
+            match result {
+                Ok(event) => {
+                    if matches!(event, ModelEvent::TextDelta(_)) && !text_started && !matches!(protocol, Protocol::Chat) {
+                        for (name, value) in stream_events(protocol, &ModelEvent::TextStart, &id, &model, &output, &mut text_started) {
+                            yield Ok(Event::default().event(name).data(value.to_string()));
+                        }
+                    }
+                    if matches!(event, ModelEvent::Done(_)) {
+                        if text_started && !text_closed {
+                            for (name, value) in stream_events(protocol, &ModelEvent::TextEnd, &id, &model, &output, &mut text_started) {
+                                yield Ok(Event::default().event(name).data(value.to_string()));
+                            }
+                        }
+                        for index in output.tools.keys().filter(|index| !closed_tools.contains(*index)).copied().collect::<Vec<_>>() {
+                            for (name, value) in stream_events(protocol, &ModelEvent::ToolCallEnd { index }, &id, &model, &output, &mut text_started) {
+                                yield Ok(Event::default().event(name).data(value.to_string()));
+                            }
+                        }
+                    }
+                    output.update(&event);
+                    for (name, value) in stream_events(protocol, &event, &id, &model, &output, &mut text_started) {
+                        yield Ok(Event::default().event(name).data(value.to_string()));
+                    }
+                    if matches!(event, ModelEvent::TextEnd | ModelEvent::Done(_)) {
+                        text_closed = true;
+                    }
+                    if let ModelEvent::ToolCallEnd { index } = event {
+                        closed_tools.insert(index);
+                    }
+                }
+                Err(error) => {
+                    yield Ok(Event::default().event("error").data(json!({"error":{"message":error.to_string(),"type":"upstream_error"}}).to_string()));
+                    return;
+                }
+            }
+        }
+        if output.finish.is_some() && matches!(protocol, Protocol::Chat) {
+            yield Ok(Event::default().data("[DONE]"));
+        }
+    };
+    Sse::new(events)
+        .keep_alive(KeepAlive::default())
+        .into_response()
+}
+
+fn chat_chunk(id: &str, model: &str, delta: Value, finish: Value) -> Value {
+    json!({"id":id,"object":"chat.completion.chunk","created":0,"model":model,
+        "choices":[{"index":0,"delta":delta,"finish_reason":finish}]})
+}
+
+fn stream_events(
+    protocol: Protocol,
+    event: &ModelEvent,
+    id: &str,
+    model: &str,
+    output: &Output,
+    text_started: &mut bool,
+) -> Vec<(&'static str, Value)> {
+    match protocol {
+        Protocol::Chat => match event {
+            ModelEvent::TextDelta(delta) => vec![(
+                "message",
+                chat_chunk(id, model, json!({"content":delta}), Value::Null),
+            )],
+            ModelEvent::ToolCallStart {
+                index,
+                call_id,
+                name,
+            } => vec![(
+                "message",
+                chat_chunk(
+                    id,
+                    model,
+                    json!({"tool_calls":[{"index":index,"id":call_id,"type":"function","function":{"name":name,"arguments":""}}]}),
+                    Value::Null,
+                ),
+            )],
+            ModelEvent::ToolCallArgumentsDelta { index, delta } => vec![(
+                "message",
+                chat_chunk(
+                    id,
+                    model,
+                    json!({"tool_calls":[{"index":index,"function":{"arguments":delta}}]}),
+                    Value::Null,
+                ),
+            )],
+            ModelEvent::Done(reason) => {
+                let finish = match reason {
+                    FinishReason::Stop => "stop",
+                    FinishReason::Length => "length",
+                    FinishReason::ToolUse => "tool_calls",
+                };
+                let mut events = vec![("message", chat_chunk(id, model, json!({}), json!(finish)))];
+                if output.usage.is_some() {
+                    events.push((
+                        "message",
+                        json!({"id":id,"object":"chat.completion.chunk","created":0,"model":model,
+                            "choices":[],"usage":output.usage_json(protocol)}),
+                    ));
+                }
+                events
+            }
+            _ => Vec::new(),
+        },
+        Protocol::Responses => match event {
+            ModelEvent::TextStart if !*text_started => {
+                *text_started = true;
+                vec![
+                    (
+                        "response.output_item.added",
+                        json!({"type":"response.output_item.added","output_index":0,"item":{"type":"message","id":format!("msg_{id}"),"status":"in_progress","role":"assistant","content":[]}}),
+                    ),
+                    (
+                        "response.content_part.added",
+                        json!({"type":"response.content_part.added","output_index":0,"content_index":0,"part":{"type":"output_text","text":"","annotations":[]}}),
+                    ),
+                ]
+            }
+            ModelEvent::TextDelta(delta) => vec![(
+                "response.output_text.delta",
+                json!({"type":"response.output_text.delta","delta":delta,"output_index":0,"content_index":0}),
+            )],
+            ModelEvent::TextEnd if *text_started => vec![
+                (
+                    "response.output_text.done",
+                    json!({"type":"response.output_text.done","text":output.text,"output_index":0,"content_index":0}),
+                ),
+                (
+                    "response.content_part.done",
+                    json!({"type":"response.content_part.done","output_index":0,"content_index":0,"part":{"type":"output_text","text":output.text,"annotations":[]}}),
+                ),
+                (
+                    "response.output_item.done",
+                    json!({"type":"response.output_item.done","output_index":0,"item":{"type":"message","id":format!("msg_{id}"),"status":"completed","role":"assistant","content":[{"type":"output_text","text":output.text,"annotations":[]}]}}),
+                ),
+            ],
+            ModelEvent::ToolCallStart {
+                index,
+                call_id,
+                name,
+            } => vec![(
+                "response.output_item.added",
+                json!({"type":"response.output_item.added","output_index":index + usize::from(*text_started),"item":{"type":"function_call","id":format!("fc_{call_id}"),"call_id":call_id,"name":name,"arguments":"","status":"in_progress"}}),
+            )],
+            ModelEvent::ToolCallArgumentsDelta { index, delta } => vec![(
+                "response.function_call_arguments.delta",
+                json!({"type":"response.function_call_arguments.delta","output_index":index + usize::from(*text_started),"delta":delta}),
+            )],
+            ModelEvent::ToolCallEnd { index } => {
+                let tool = output.tools.get(index);
+                let arguments = tool.map(|tool| tool.arguments.as_str()).unwrap_or_default();
+                let call_id = tool.map(|tool| tool.id.as_str()).unwrap_or_default();
+                vec![
+                    (
+                        "response.function_call_arguments.done",
+                        json!({"type":"response.function_call_arguments.done","output_index":index + usize::from(*text_started),"arguments":arguments}),
+                    ),
+                    (
+                        "response.output_item.done",
+                        json!({"type":"response.output_item.done","output_index":index + usize::from(*text_started),"item":{"type":"function_call","id":format!("fc_{call_id}"),"call_id":call_id,"name":tool.map(|tool| tool.name.as_str()).unwrap_or("tool"),"arguments":arguments,"status":"completed"}}),
+                    ),
+                ]
+            }
+            ModelEvent::Done(_) => vec![(
+                "response.completed",
+                json!({"type":"response.completed","response":output.json(protocol,id,model)}),
+            )],
+            _ => Vec::new(),
+        },
+        Protocol::Messages => match event {
+            ModelEvent::TextStart => {
+                if *text_started {
+                    Vec::new()
+                } else {
+                    *text_started = true;
+                    vec![(
+                        "content_block_start",
+                        json!({"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}),
+                    )]
+                }
+            }
+            ModelEvent::TextDelta(delta) => {
+                let mut events = Vec::new();
+                if !*text_started {
+                    *text_started = true;
+                    events.push(("content_block_start",json!({"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}})));
+                }
+                events.push(("content_block_delta",json!({"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":delta}})));
+                events
+            }
+            ModelEvent::TextEnd => {
+                if *text_started {
+                    vec![(
+                        "content_block_stop",
+                        json!({"type":"content_block_stop","index":0}),
+                    )]
+                } else {
+                    Vec::new()
+                }
+            }
+            ModelEvent::ToolCallStart {
+                index,
+                call_id,
+                name,
+            } => vec![(
+                "content_block_start",
+                json!({"type":"content_block_start","index":index + usize::from(*text_started),"content_block":{"type":"tool_use","id":call_id,"name":name,"input":{}}}),
+            )],
+            ModelEvent::ToolCallArgumentsDelta { index, delta } => vec![(
+                "content_block_delta",
+                json!({"type":"content_block_delta","index":index + usize::from(*text_started),"delta":{"type":"input_json_delta","partial_json":delta}}),
+            )],
+            ModelEvent::ToolCallEnd { index } => vec![(
+                "content_block_stop",
+                json!({"type":"content_block_stop","index":index + usize::from(*text_started)}),
+            )],
+            ModelEvent::Done(reason) => {
+                let stop = match reason {
+                    FinishReason::Stop => "end_turn",
+                    FinishReason::Length => "max_tokens",
+                    FinishReason::ToolUse => "tool_use",
+                };
+                vec![
+                    (
+                        "message_delta",
+                        json!({"type":"message_delta","delta":{"stop_reason":stop,"stop_sequence":null},"usage":output.usage_json(protocol)}),
+                    ),
+                    ("message_stop", json!({"type":"message_stop"})),
+                ]
+            }
+            _ => Vec::new(),
+        },
+    }
+}
diff --git a/server/src/api/byok/protocol.rs b/server/src/api/byok/protocol.rs
new file mode 100644
index 0000000..b6c8616
--- /dev/null
+++ b/server/src/api/byok/protocol.rs
@@ -0,0 +1,471 @@
+use base64::Engine;
+use serde_json::Value;
+
+use crate::{
+    model::{
+        ContentPart, ModelRequest, ModelSpec, ProjectedContent, ProjectedMessage, PromptSpec,
+        ProviderType, Role, ToolCallContent, ToolDefinition, ToolResultContent,
+    },
+    Error, Result,
+};
+
+#[derive(Clone, Copy, Debug)]
+pub(super) enum Protocol {
+    Chat,
+    Responses,
+    Messages,
+}
+
+impl Protocol {
+    pub(super) fn provider_type(self) -> ProviderType {
+        match self {
+            Self::Chat => ProviderType::OpenAiChat,
+            Self::Responses => ProviderType::OpenAiResponses,
+            Self::Messages => ProviderType::Anthropic,
+        }
+    }
+}
+
+pub(super) struct ParsedRequest {
+    pub public_model_id: String,
+    pub request: ModelRequest,
+    pub stream: bool,
+}
+
+pub(super) fn parse(protocol: Protocol, body: &Value) -> Result<ParsedRequest> {
+    let public_model_id = required_string(body, "model")?.to_owned();
+    let stream = body.get("stream").and_then(Value::as_bool).unwrap_or(false);
+    let mut prompt = PromptSpec {
+        instructions: String::new(),
+        tools: Vec::new(),
+    };
+    let mut history = Vec::new();
+    let mut model = ModelSpec::new(&public_model_id);
+    match protocol {
+        Protocol::Chat => {
+            parse_chat_messages(body.get("messages"), &mut prompt, &mut history)?;
+            parse_tools(body.get("tools"), protocol, &mut prompt)?;
+            model.max_output_tokens = body
+                .get("max_completion_tokens")
+                .or_else(|| body.get("max_tokens"))
+                .and_then(Value::as_u64);
+        }
+        Protocol::Responses => {
+            prompt.instructions = body
+                .get("instructions")
+                .and_then(Value::as_str)
+                .unwrap_or_default()
+                .to_owned();
+            match body.get("input") {
+                Some(Value::String(text)) => history.push(text_message(0, Role::User, text)),
+                Some(input) => parse_responses_input(input, &mut history)?,
+                None => return Err(Error::Protocol("input is required".into())),
+            }
+            parse_tools(body.get("tools"), protocol, &mut prompt)?;
+            model.max_output_tokens = body.get("max_output_tokens").and_then(Value::as_u64);
+        }
+        Protocol::Messages => {
+            prompt.instructions = text_content(body.get("system")).unwrap_or_default();
+            parse_anthropic_messages(body.get("messages"), &mut history)?;
+            parse_tools(body.get("tools"), protocol, &mut prompt)?;
+            model.max_output_tokens = body.get("max_tokens").and_then(Value::as_u64);
+        }
+    }
+    if history.is_empty() {
+        return Err(Error::Protocol(
+            "at least one input message is required".into(),
+        ));
+    }
+    Ok(ParsedRequest {
+        public_model_id,
+        request: ModelRequest {
+            prompt,
+            model,
+            history,
+        },
+        stream,
+    })
+}
+
+fn required_string<'a>(value: &'a Value, field: &str) -> Result<&'a str> {
+    value
+        .get(field)
+        .and_then(Value::as_str)
+        .filter(|text| !text.is_empty())
+        .ok_or_else(|| Error::Protocol(format!("{field} is required")))
+}
+
+fn text_message(index: usize, role: Role, text: &str) -> ProjectedMessage {
+    ProjectedMessage {
+        message_id: format!("external:{index}"),
+        role,
+        content: ProjectedContent::Parts(vec![ContentPart::Text { text: text.into() }]),
+    }
+}
+
+fn text_content(value: Option<&Value>) -> Option<String> {
+    match value? {
+        Value::String(text) => Some(text.clone()),
+        Value::Array(parts) => Some(
+            parts
+                .iter()
+                .filter_map(|part| {
+                    part.as_str()
+                        .or_else(|| part.get("text").and_then(Value::as_str))
+                })
+                .collect::<Vec<_>>()
+                .join("\n"),
+        ),
+        _ => None,
+    }
+}
+
+fn parse_parts(value: Option<&Value>) -> Result<Vec<ContentPart>> {
+    let value = value.ok_or_else(|| Error::Protocol("message content is required".into()))?;
+    if let Some(text) = value.as_str() {
+        return Ok(vec![ContentPart::Text { text: text.into() }]);
+    }
+    let array = value
+        .as_array()
+        .ok_or_else(|| Error::Protocol("message content must be text or an array".into()))?;
+    array
+        .iter()
+        .map(|part| {
+            let kind = part.get("type").and_then(Value::as_str).unwrap_or("text");
+            match kind {
+                "text" | "input_text" | "output_text" => Ok(ContentPart::Text {
+                    text: required_string(part, "text")?.into(),
+                }),
+                "image_url" | "input_image" | "image" => {
+                    let url = part
+                        .pointer("/image_url/url")
+                        .or_else(|| part.get("image_url"))
+                        .or_else(|| part.pointer("/source/data"))
+                        .and_then(Value::as_str)
+                        .ok_or_else(|| Error::Protocol("image data URL is required".into()))?;
+                    let data_url = if url.starts_with("data:") {
+                        url.to_owned()
+                    } else if let Some(mime) =
+                        part.pointer("/source/media_type").and_then(Value::as_str)
+                    {
+                        format!("data:{mime};base64,{url}")
+                    } else {
+                        return Err(Error::Protocol(
+                            "only base64 image data URLs are supported".into(),
+                        ));
+                    };
+                    let (prefix, encoded) = data_url
+                        .split_once(',')
+                        .ok_or_else(|| Error::Protocol("invalid image data URL".into()))?;
+                    let mime_type = prefix
+                        .strip_prefix("data:")
+                        .and_then(|prefix| prefix.strip_suffix(";base64"))
+                        .ok_or_else(|| Error::Protocol("invalid image data URL".into()))?;
+                    let data = base64::engine::general_purpose::STANDARD
+                        .decode(encoded)
+                        .map_err(|_| Error::Protocol("invalid base64 image".into()))?;
+                    Ok(ContentPart::Image {
+                        mime_type: mime_type.into(),
+                        data,
+                    })
+                }
+                _ => Err(Error::Protocol(format!("unsupported content type: {kind}"))),
+            }
+        })
+        .collect()
+}
+
+fn parse_chat_messages(
+    value: Option<&Value>,
+    prompt: &mut PromptSpec,
+    history: &mut Vec<ProjectedMessage>,
+) -> Result<()> {
+    let messages = value
+        .and_then(Value::as_array)
+        .ok_or_else(|| Error::Protocol("messages must be an array".into()))?;
+    for (index, message) in messages.iter().enumerate() {
+        let role = required_string(message, "role")?;
+        match role {
+            "system" | "developer" => {
+                if !history.is_empty() {
+                    return Err(Error::Protocol(
+                        "system messages must precede conversation messages".into(),
+                    ));
+                }
+                let text = text_content(message.get("content"))
+                    .ok_or_else(|| Error::Protocol("system content must be text".into()))?;
+                if !prompt.instructions.is_empty() {
+                    prompt.instructions.push('\n');
+                }
+                prompt.instructions.push_str(&text);
+            }
+            "user" => history.push(ProjectedMessage {
+                message_id: format!("external:{index}"),
+                role: Role::User,
+                content: ProjectedContent::Parts(parse_parts(message.get("content"))?),
+            }),
+            "assistant" => {
+                let text = text_content(message.get("content")).unwrap_or_default();
+                let calls = message
+                    .get("tool_calls")
+                    .and_then(Value::as_array)
+                    .map(|calls| {
+                        calls
+                            .iter()
+                            .enumerate()
+                            .map(|(index, call)| {
+                                let function = call.get("function").ok_or_else(|| {
+                                    Error::Protocol("tool function is required".into())
+                                })?;
+                                let arguments = required_string(function, "arguments")?;
+                                Ok(ToolCallContent {
+                                    index,
+                                    call_id: required_string(call, "id")?.into(),
+                                    name: required_string(function, "name")?.into(),
+                                    arguments: serde_json::from_str(arguments)?,
+                                })
+                            })
+                            .collect::<Result<Vec<_>>>()
+                    })
+                    .transpose()?
+                    .unwrap_or_default();
+                history.push(ProjectedMessage {
+                    message_id: format!("external:{index}"),
+                    role: Role::Assistant,
+                    content: ProjectedContent::Assistant {
+                        text,
+                        thinking: String::new(),
+                        replay_state: None,
+                        calls,
+                    },
+                });
+            }
+            "tool" => history.push(ProjectedMessage {
+                message_id: format!("external:{index}"),
+                role: Role::Tool,
+                content: ProjectedContent::ToolResult(ToolResultContent {
+                    call_id: required_string(message, "tool_call_id")?.into(),
+                    name: message
+                        .get("name")
+                        .and_then(Value::as_str)
+                        .map(str::to_owned)
+                        .or_else(|| {
+                            tool_name(
+                                history,
+                                message
+                                    .get("tool_call_id")
+                                    .and_then(Value::as_str)
+                                    .unwrap_or_default(),
+                            )
+                        })
+                        .unwrap_or_else(|| "tool".into()),
+                    content: text_content(message.get("content")).unwrap_or_default(),
+                    is_error: false,
+                    image: None,
+                    provider_parts: Vec::new(),
+                }),
+            }),
+            _ => return Err(Error::Protocol(format!("unsupported role: {role}"))),
+        }
+    }
+    Ok(())
+}
+
+fn parse_responses_input(value: &Value, history: &mut Vec<ProjectedMessage>) -> Result<()> {
+    let items = value
+        .as_array()
+        .ok_or_else(|| Error::Protocol("input must be text or an array".into()))?;
+    for (index, item) in items.iter().enumerate() {
+        match item.get("type").and_then(Value::as_str) {
+            Some("function_call_output") => history.push(ProjectedMessage {
+                message_id: format!("external:{index}"),
+                role: Role::Tool,
+                content: ProjectedContent::ToolResult(ToolResultContent {
+                    call_id: required_string(item, "call_id")?.into(),
+                    name: tool_name(history, required_string(item, "call_id")?)
+                        .unwrap_or_else(|| "tool".into()),
+                    content: text_content(item.get("output")).unwrap_or_default(),
+                    is_error: false,
+                    image: None,
+                    provider_parts: Vec::new(),
+                }),
+            }),
+            Some("function_call") => history.push(ProjectedMessage {
+                message_id: format!("external:{index}"),
+                role: Role::Assistant,
+                content: ProjectedContent::Assistant {
+                    text: String::new(),
+                    thinking: String::new(),
+                    replay_state: None,
+                    calls: vec![ToolCallContent {
+                        index: 0,
+                        call_id: required_string(item, "call_id")?.into(),
+                        name: required_string(item, "name")?.into(),
+                        arguments: serde_json::from_str(required_string(item, "arguments")?)?,
+                    }],
+                },
+            }),
+            _ => {
+                let role = item.get("role").and_then(Value::as_str).unwrap_or("user");
+                let role = match role {
+                    "user" => Role::User,
+                    "assistant" => Role::Assistant,
+                    _ => return Err(Error::Protocol(format!("unsupported role: {role}"))),
+                };
+                history.push(ProjectedMessage {
+                    message_id: format!("external:{index}"),
+                    role,
+                    content: ProjectedContent::Parts(parse_parts(item.get("content"))?),
+                });
+            }
+        }
+    }
+    Ok(())
+}
+
+fn parse_anthropic_messages(
+    value: Option<&Value>,
+    history: &mut Vec<ProjectedMessage>,
+) -> Result<()> {
+    let messages = value
+        .and_then(Value::as_array)
+        .ok_or_else(|| Error::Protocol("messages must be an array".into()))?;
+    for (index, message) in messages.iter().enumerate() {
+        let role = required_string(message, "role")?;
+        let content = message
+            .get("content")
+            .ok_or_else(|| Error::Protocol("content is required".into()))?;
+        if let Some(blocks) = content.as_array() {
+            let mut text_parts = Vec::new();
+            let mut calls = Vec::new();
+            for (block_index, block) in blocks.iter().enumerate() {
+                match block.get("type").and_then(Value::as_str) {
+                    Some("tool_use") => calls.push(ToolCallContent {
+                        index: calls.len(),
+                        call_id: required_string(block, "id")?.into(),
+                        name: required_string(block, "name")?.into(),
+                        arguments: block
+                            .get("input")
+                            .cloned()
+                            .unwrap_or(Value::Object(Default::default())),
+                    }),
+                    Some("tool_result") => {
+                        if role != "user" {
+                            return Err(Error::Protocol(
+                                "tool_result must be in a user message".into(),
+                            ));
+                        }
+                        if !text_parts.is_empty() {
+                            history.push(ProjectedMessage {
+                                message_id: format!("external:{index}:{block_index}:text"),
+                                role: Role::User,
+                                content: ProjectedContent::Parts(std::mem::take(&mut text_parts)),
+                            });
+                        }
+                        let call_id = required_string(block, "tool_use_id")?;
+                        history.push(ProjectedMessage {
+                            message_id: format!("external:{index}:{block_index}:tool"),
+                            role: Role::Tool,
+                            content: ProjectedContent::ToolResult(ToolResultContent {
+                                call_id: call_id.into(),
+                                name: tool_name(history, call_id).unwrap_or_else(|| "tool".into()),
+                                content: text_content(block.get("content")).unwrap_or_default(),
+                                is_error: block
+                                    .get("is_error")
+                                    .and_then(Value::as_bool)
+                                    .unwrap_or(false),
+                                image: None,
+                                provider_parts: Vec::new(),
+                            }),
+                        });
+                    }
+                    _ => text_parts.extend(parse_parts(Some(&Value::Array(vec![block.clone()])))?),
+                }
+            }
+            if role == "assistant" {
+                let text = text_parts
+                    .iter()
+                    .filter_map(|part| {
+                        if let ContentPart::Text { text } = part {
+                            Some(text.as_str())
+                        } else {
+                            None
+                        }
+                    })
+                    .collect::<Vec<_>>()
+                    .join("");
+                history.push(ProjectedMessage {
+                    message_id: format!("external:{index}"),
+                    role: Role::Assistant,
+                    content: ProjectedContent::Assistant {
+                        text,
+                        thinking: String::new(),
+                        replay_state: None,
+                        calls,
+                    },
+                });
+            } else if !text_parts.is_empty() {
+                history.push(ProjectedMessage {
+                    message_id: format!("external:{index}"),
+                    role: Role::User,
+                    content: ProjectedContent::Parts(text_parts),
+                });
+            }
+        } else {
+            let role = match role {
+                "user" => Role::User,
+                "assistant" => Role::Assistant,
+                _ => return Err(Error::Protocol(format!("unsupported role: {role}"))),
+            };
+            history.push(ProjectedMessage {
+                message_id: format!("external:{index}"),
+                role,
+                content: ProjectedContent::Parts(parse_parts(Some(content))?),
+            });
+        }
+    }
+    Ok(())
+}
+
+fn parse_tools(value: Option<&Value>, protocol: Protocol, prompt: &mut PromptSpec) -> Result<()> {
+    let Some(value) = value else {
+        return Ok(());
+    };
+    let tools = value
+        .as_array()
+        .ok_or_else(|| Error::Protocol("tools must be an array".into()))?;
+    for tool in tools {
+        let function = if matches!(protocol, Protocol::Chat) {
+            tool.get("function").unwrap_or(tool)
+        } else {
+            tool
+        };
+        prompt.tools.push(ToolDefinition {
+            name: required_string(function, "name")?.into(),
+            description: function
+                .get("description")
+                .and_then(Value::as_str)
+                .unwrap_or_default()
+                .into(),
+            parameters: function
+                .get("parameters")
+                .or_else(|| function.get("input_schema"))
+                .cloned()
+                .unwrap_or(serde_json::json!({"type":"object","properties":{}})),
+        });
+    }
+    Ok(())
+}
+
+fn tool_name(history: &[ProjectedMessage], call_id: &str) -> Option<String> {
+    history
+        .iter()
+        .rev()
+        .find_map(|message| match &message.content {
+            ProjectedContent::Assistant { calls, .. } => calls
+                .iter()
+                .find(|call| call.call_id == call_id)
+                .map(|call| call.name.clone()),
+            _ => None,
+        })
+}
diff --git a/server/src/api/mod.rs b/server/src/api/mod.rs
index d557379..19e04ac 100644
--- a/server/src/api/mod.rs
+++ b/server/src/api/mod.rs
@@ -1,5 +1,6 @@
 //! Exposes the HTTP and Connect API layer.
 
+pub mod byok;
 pub mod cursor;
 mod router;
 
diff --git a/server/src/app.rs b/server/src/app.rs
index 6f97c86..55d1007 100644
--- a/server/src/app.rs
+++ b/server/src/app.rs
@@ -52,6 +52,17 @@ impl App {
             config.provider_request_timeout,
             config.provider_stream_idle_timeout,
         ));
+        let byok = api::byok::router(
+            store.clone(),
+            plugins.clone(),
+            provider.clone(),
+            Some(api::byok::NativeForwarder::new(
+                store.clone(),
+                clients.clone(),
+                config.provider_request_timeout,
+                config.provider_stream_idle_timeout,
+            )),
+        );
         let registry = TransportRegistry::with_plugins(
             store.clone(),
             provider.clone(),
@@ -69,7 +80,7 @@ impl App {
             config.app_version.clone(),
         )?;
         let harness = control.cursor_harness().clone();
-        let mut router = api::router(registry.clone(), clients)?;
+        let mut router = api::router(registry.clone(), clients)?.merge(byok);
         router = match &config.console {
             Some(ConsoleSource::Directory(directory)) => {
                 router.merge(control::web_router(control.clone(), directory))
diff --git a/server/src/control/mod.rs b/server/src/control/mod.rs
index 28df780..9cad7ba 100644
--- a/server/src/control/mod.rs
+++ b/server/src/control/mod.rs
@@ -196,6 +196,10 @@ pub fn api_router(service: ControlService) -> Router {
             "/__byok-api__/api/settings/ports",
             get(settings::get_ports).put(settings::update_ports),
         )
+        .route(
+            "/__byok-api__/api/settings/external-api",
+            get(settings::get_external_api).put(settings::update_external_api),
+        )
         .route(
             "/__byok-api__/api/settings/storage/statistics",
             get(settings::get_storage).delete(settings::clear_storage),
diff --git a/server/src/control/service.rs b/server/src/control/service.rs
index 405b4f2..da8acfd 100644
--- a/server/src/control/service.rs
+++ b/server/src/control/service.rs
@@ -28,8 +28,8 @@ use crate::{
     plugin::{PluginDescriptor, PluginRegistry, PluginRuntime, PluginRuntimeStatus},
     provider::{is_valid_response_event, ModelEvent, Provider},
     store::{
-        CommitSettings, DesktopSettings, PortSettings, ProxySettings, ProxySettingsInput,
-        StatisticsStorage, Store, TabSettings, TokenPricingSettings,
+        CommitSettings, DesktopSettings, ExternalApiSettings, PortSettings, ProxySettings,
+        ProxySettingsInput, StatisticsStorage, Store, TabSettings, TokenPricingSettings,
     },
     Error, Result,
 };
@@ -605,10 +605,13 @@ impl ControlService {
             .llm_calls(limit)
             .await?
             .into_iter()
-            .map(|call| CallSummary {
-                call,
-                call_kind: "provider_llm",
-                route: "local_byok",
+            .map(|call| {
+                let route = call_route(&call.run_id);
+                CallSummary {
+                    call,
+                    call_kind: "provider_llm",
+                    route,
+                }
             })
             .collect::<Vec<_>>();
         calls.extend(
@@ -626,13 +629,14 @@ impl ControlService {
     pub async fn call(&self, call_id: &str) -> Result<CallDetail> {
         if let Some(call) = self.store.llm_call(call_id).await? {
             let cursor_trace = self.cursor_trace_detail(&call.run_id).await?;
+            let route = call_route(&call.run_id);
             return Ok(CallDetail {
                 request: self.store.llm_call_request(call_id).await?,
                 response_chunks: self.store.llm_call_chunks(call_id).await?,
                 call: CallSummary {
                     call,
                     call_kind: "provider_llm",
-                    route: "local_byok",
+                    route,
                 },
                 cursor_trace,
             });
@@ -691,6 +695,17 @@ impl ControlService {
         self.store.port_settings().await
     }
 
+    pub async fn external_api_settings(&self) -> Result<ExternalApiSettings> {
+        self.store.external_api_settings().await
+    }
+
+    pub async fn set_external_api_settings(
+        &self,
+        settings: ExternalApiSettings,
+    ) -> Result<ExternalApiSettings> {
+        self.store.set_external_api_settings(settings).await
+    }
+
     pub async fn set_ports(&self, settings: PortSettings) -> Result<PortSettings> {
         self.store.set_port_settings(settings).await?;
         Ok(settings)
@@ -761,6 +776,14 @@ impl ControlService {
     }
 }
 
+fn call_route(run_id: &str) -> &'static str {
+    if run_id.starts_with("external-api:") {
+        "external_api"
+    } else {
+        "local_byok"
+    }
+}
+
 fn official_call(trace: CursorRunTraceSummary) -> CallSummary {
     let model_id = trace.model_id.clone().unwrap_or_else(|| "Cursor".into());
     let ttfb = trace
diff --git a/server/src/control/settings.rs b/server/src/control/settings.rs
index 003c1c9..2f64124 100644
--- a/server/src/control/settings.rs
+++ b/server/src/control/settings.rs
@@ -8,8 +8,8 @@ use axum::{
 use serde::{Deserialize, Serialize};
 
 use crate::store::{
-    CommitPromptLocale, CommitSettings, DesktopSettings, PortSettings, ProxySettings,
-    ProxySettingsInput, StatisticsStorage, StatisticsStorageScope, TabSettings,
+    CommitPromptLocale, CommitSettings, DesktopSettings, ExternalApiSettings, PortSettings,
+    ProxySettings, ProxySettingsInput, StatisticsStorage, StatisticsStorageScope, TabSettings,
     TokenPricingSettings,
 };
 
@@ -37,6 +37,19 @@ pub async fn update_ports(
     Ok(Json(service.set_ports(settings).await?))
 }
 
+pub async fn get_external_api(
+    State(service): State<ControlService>,
+) -> Result<Json<ExternalApiSettings>> {
+    Ok(Json(service.external_api_settings().await?))
+}
+
+pub async fn update_external_api(
+    State(service): State<ControlService>,
+    Json(settings): Json<ExternalApiSettings>,
+) -> Result<Json<ExternalApiSettings>> {
+    Ok(Json(service.set_external_api_settings(settings).await?))
+}
+
 pub async fn get_storage(State(service): State<ControlService>) -> Result<Json<StatisticsStorage>> {
     Ok(Json(service.statistics_storage().await?))
 }
diff --git a/server/src/provider/anthropic.rs b/server/src/provider/anthropic.rs
index f9e2c0a..e2a47c8 100644
--- a/server/src/provider/anthropic.rs
+++ b/server/src/provider/anthropic.rs
@@ -480,7 +480,7 @@ fn required_u64(value: &Value, name: &str) -> Result<u64> {
         .ok_or_else(|| Error::Provider(format!("Anthropic event is missing {name}")))
 }
 
-fn anthropic_usage(value: &Value) -> Usage {
+pub(crate) fn anthropic_usage(value: &Value) -> Usage {
     let input_tokens = value.get("input_tokens").and_then(Value::as_u64);
     let cache_read_tokens = value.get("cache_read_input_tokens").and_then(Value::as_u64);
     let cache_write_tokens = value
diff --git a/server/src/provider/mod.rs b/server/src/provider/mod.rs
index 80cffb1..83d1941 100644
--- a/server/src/provider/mod.rs
+++ b/server/src/provider/mod.rs
@@ -21,6 +21,21 @@ pub use event::*;
 pub use openai_chat::OpenAiChatProvider;
 pub use openai_responses::OpenAiResponsesProvider;
 pub use recorder::CallRecorder;
+pub(crate) use router::custom_headers;
+
+pub(crate) fn native_usage(
+    kind: crate::model::ProviderType,
+    value: &serde_json::Value,
+) -> crate::model::Usage {
+    match kind {
+        crate::model::ProviderType::OpenAiChat => openai_chat::openai_usage(value),
+        crate::model::ProviderType::OpenAiResponses => openai_responses::responses_usage(value),
+        crate::model::ProviderType::Anthropic => anthropic::anthropic_usage(value),
+        crate::model::ProviderType::Plugin => {
+            unreachable!("plugin calls have no native HTTP protocol")
+        }
+    }
+}
 pub use router::{build as build_provider, ProviderRouter};
 
 pub type ProviderStream = Pin<Box<dyn Stream<Item = Result<ModelEvent>> + Send>>;
diff --git a/server/src/provider/openai_responses.rs b/server/src/provider/openai_responses.rs
index 275f45a..bac1b90 100644
--- a/server/src/provider/openai_responses.rs
+++ b/server/src/provider/openai_responses.rs
@@ -522,7 +522,7 @@ fn required_u64(value: &Value, name: &str) -> Result<u64> {
         .ok_or_else(|| Error::Provider(format!("OpenAI Responses event is missing {name}")))
 }
 
-fn responses_usage(value: &Value) -> Usage {
+pub(crate) fn responses_usage(value: &Value) -> Usage {
     let input_tokens = value.get("input_tokens").and_then(Value::as_u64);
     Usage {
         input_tokens,
diff --git a/server/src/provider/recorder.rs b/server/src/provider/recorder.rs
index 652fc4e..e60f176 100644
--- a/server/src/provider/recorder.rs
+++ b/server/src/provider/recorder.rs
@@ -41,7 +41,7 @@ pub struct CallRecorder {
     inner: Arc<Inner>,
 }
 
-pub(super) struct CancelOnDrop {
+pub(crate) struct CancelOnDrop {
     recorder: CallRecorder,
 }
 
@@ -133,7 +133,7 @@ impl CallRecorder {
         self.inner.finished.load(Ordering::Acquire)
     }
 
-    pub(super) fn cancel_on_drop(&self) -> CancelOnDrop {
+    pub(crate) fn cancel_on_drop(&self) -> CancelOnDrop {
         CancelOnDrop {
             recorder: self.clone(),
         }
diff --git a/server/src/provider/router.rs b/server/src/provider/router.rs
index 17bbd7f..6d8397c 100644
--- a/server/src/provider/router.rs
+++ b/server/src/provider/router.rs
@@ -308,7 +308,7 @@ fn root_error_message(error: &(dyn std::error::Error + 'static)) -> String {
     current.to_string()
 }
 
-fn custom_headers(
+pub(crate) fn custom_headers(
     value: &serde_json::Value,
     conversation_id: &str,
 ) -> Result<reqwest::header::HeaderMap> {
diff --git a/server/src/store/settings.rs b/server/src/store/settings.rs
index 1a2673c..d71b13a 100644
--- a/server/src/store/settings.rs
+++ b/server/src/store/settings.rs
@@ -13,6 +13,7 @@ const DESKTOP_SETTINGS_KEY: &str = "desktop_lifecycle";
 const COMMIT_SETTINGS_KEY: &str = "commit_settings";
 const CURSOR_TAKEOVER_ENABLED_KEY: &str = "cursor_takeover_enabled";
 const PRICING_SETTINGS_KEY: &str = "token_pricing";
+const EXTERNAL_API_SETTINGS_KEY: &str = "external_api";
 
 /// Embedded default system prompts for commit message generation.
 pub const DEFAULT_COMMIT_PROMPT_ZH_CN: &str = include_str!("../../prompt/cursor/commit/zh-CN.md");
@@ -26,6 +27,12 @@ pub struct PortSettings {
     pub service_port: u16,
 }
 
+#[derive(Clone, Debug, Default, Deserialize, PartialEq, Eq, Serialize)]
+pub struct ExternalApiSettings {
+    pub enabled: bool,
+    pub api_key: String,
+}
+
 #[derive(Clone, Copy, Debug, Deserialize, PartialEq, Serialize)]
 pub struct TokenPricingSettings {
     pub input_per_million: f64,
@@ -212,6 +219,39 @@ fn read_proxy_settings(value: &str) -> ProxySettingsSecret {
 }
 
 impl Store {
+    pub async fn external_api_settings(&self) -> Result<ExternalApiSettings> {
+        let value = sqlx::query_scalar::<_, String>(
+            "SELECT value_json FROM service_settings WHERE setting_key = ?",
+        )
+        .bind(EXTERNAL_API_SETTINGS_KEY)
+        .fetch_optional(&self.pool)
+        .await?;
+        value
+            .map(|value| serde_json::from_str(&value).map_err(Into::into))
+            .unwrap_or_else(|| Ok(ExternalApiSettings::default()))
+    }
+
+    pub async fn set_external_api_settings(
+        &self,
+        mut settings: ExternalApiSettings,
+    ) -> Result<ExternalApiSettings> {
+        settings.api_key = settings.api_key.trim().to_owned();
+        if settings.enabled && settings.api_key.is_empty() {
+            return Err(crate::Error::Config(
+                "external API key is required when enabled".into(),
+            ));
+        }
+        let value_json = serde_json::to_string(&settings)?;
+        let _write = self.writes.lock().await;
+        sqlx::query("INSERT INTO service_settings(setting_key, value_json, updated_at_ms) VALUES (?, ?, ?) ON CONFLICT(setting_key) DO UPDATE SET value_json = excluded.value_json, updated_at_ms = excluded.updated_at_ms")
+            .bind(EXTERNAL_API_SETTINGS_KEY)
+            .bind(value_json)
+            .bind(now_ms())
+            .execute(&self.pool)
+            .await?;
+        Ok(settings)
+    }
+
     pub(crate) async fn cursor_takeover_enabled(&self) -> Result<bool> {
         let value = sqlx::query_scalar::<_, String>(
             "SELECT value_json FROM service_settings WHERE setting_key = ?",
@@ -495,9 +535,9 @@ impl Store {
 #[cfg(test)]
 mod tests {
     use super::{
-        read_proxy_settings, CommitPromptLocale, CommitSettings, ProxyMode, ProxySettingsInput,
-        ProxySettingsSecret, Store, TokenPricingSettings, DEFAULT_COMMIT_PROMPT_EN_US,
-        DEFAULT_COMMIT_PROMPT_ZH_CN, PROXY_SETTINGS_KEY,
+        read_proxy_settings, CommitPromptLocale, CommitSettings, ExternalApiSettings, ProxyMode,
+        ProxySettingsInput, ProxySettingsSecret, Store, TokenPricingSettings,
+        DEFAULT_COMMIT_PROMPT_EN_US, DEFAULT_COMMIT_PROMPT_ZH_CN, PROXY_SETTINGS_KEY,
     };
 
     /// The `outbound_proxy` row exactly as builds before the `system` -> `default`
@@ -632,4 +672,43 @@ mod tests {
 
         assert_eq!(store.pricing_settings().await.unwrap(), custom);
     }
+
+    #[tokio::test]
+    async fn external_api_requires_a_key_and_persists_its_switch() {
+        let directory = tempfile::tempdir().unwrap();
+        let url = format!("sqlite://{}", directory.path().join("test.db").display());
+        let store = Store::connect(&url).await.unwrap();
+
+        assert_eq!(
+            store.external_api_settings().await.unwrap(),
+            ExternalApiSettings::default()
+        );
+        assert!(store
+            .set_external_api_settings(ExternalApiSettings {
+                enabled: true,
+                api_key: String::new(),
+            })
+            .await
+            .is_err());
+        let settings = ExternalApiSettings {
+            enabled: true,
+            api_key: "local-test-key".into(),
+        };
+        assert_eq!(
+            store
+                .set_external_api_settings(settings.clone())
+                .await
+                .unwrap(),
+            settings
+        );
+        assert_eq!(
+            Store::connect(&url)
+                .await
+                .unwrap()
+                .external_api_settings()
+                .await
+                .unwrap(),
+            settings
+        );
+    }
 }
diff --git a/server/tests/external_api.rs b/server/tests/external_api.rs
new file mode 100644
index 0000000..97b5a98
--- /dev/null
+++ b/server/tests/external_api.rs
@@ -0,0 +1,903 @@
+#[path = "support/fake_provider.rs"]
+mod fake_provider;
+#[path = "support/fixtures.rs"]
+mod fixtures;
+
+use std::{collections::HashSet, sync::Arc, time::Duration};
+
+use axum::{
+    body::{to_bytes, Body},
+    http::{header, HeaderMap, Request, StatusCode},
+    response::IntoResponse,
+    routing::post,
+    Json, Router,
+};
+use cursor_server::{
+    api::byok,
+    control,
+    model::{
+        ModelConfigInput, ModelType, ProjectedContent, Usage, OPENAI_CHAT_ENDPOINT,
+        OPENAI_RESPONSES_ENDPOINT,
+    },
+    network::NetworkClients,
+    plugin::{PluginRegistry, PluginRuntime},
+    provider::{FinishReason, ModelEvent, ProviderRouter},
+    store::ExternalApiSettings,
+};
+use serde_json::{json, Value};
+use tower::ServiceExt;
+
+fn model_input() -> ModelConfigInput {
+    ModelConfigInput {
+        sort_order: 0,
+        display_name: "Example".into(),
+        group_name: Some("work".into()),
+        model_type: ModelType::OpenAi,
+        base_url: "https://example.com/v1".into(),
+        use_full_url: false,
+        api_key: "upstream".into(),
+        tooltip_data: "test".into(),
+        model_id: "qwen/model".into(),
+        reasoning_effort: None,
+        openai_endpoint: OPENAI_CHAT_ENDPOINT.into(),
+        openai_extra_params_enabled: false,
+        openai_extra_params: json!({}),
+        custom_headers_enabled: false,
+        custom_headers: json!({}),
+        anthropic_extra_params_enabled: false,
+        anthropic_extra_params: json!({}),
+        context_window_tokens: None,
+        max_completion_tokens: None,
+        anthropic_max_tokens: None,
+        anthropic_thinking_effort: None,
+        thinking_budget_tokens: None,
+    }
+}
+
+async fn setup() -> (
+    axum::Router,
+    fake_provider::FakeProvider,
+    cursor_server::store::Store,
+    tempfile::TempDir,
+) {
+    let (directory, store) = fixtures::temp_store().await;
+    store.create_model(&model_input()).await.unwrap();
+    let runtime = PluginRuntime::managed().unwrap();
+    let plugins = PluginRegistry::managed(store.clone(), runtime.clone(), "0.1.0".into()).unwrap();
+    let provider = fake_provider::FakeProvider::default();
+    let shared_provider = Arc::new(provider.clone());
+    let control = control::ControlService::new(
+        store.clone(),
+        shared_provider.clone(),
+        runtime,
+        plugins.clone(),
+        NetworkClients::new(store.clone()),
+        "0.1.0".into(),
+    )
+    .unwrap();
+    let router = byok::router(store.clone(), plugins, shared_provider, None)
+        .merge(control::api_router(control));
+    (router, provider, store, directory)
+}
+
+#[tokio::test]
+async fn management_settings_enable_the_external_route_without_restart() {
+    let (router, _provider, _store, _directory) = setup().await;
+    let (status, body) = send(
+        router.clone(),
+        "GET",
+        "/__byok-api__/api/settings/external-api",
+        None,
+        json!({}),
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK);
+    assert_eq!(
+        serde_json::from_str::<Value>(&body).unwrap()["enabled"],
+        false
+    );
+    let (status, _) = send(
+        router.clone(),
+        "PUT",
+        "/__byok-api__/api/settings/external-api",
+        None,
+        json!({"enabled":true,"api_key":"changed-key"}),
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK);
+    assert_eq!(
+        send(
+            router,
+            "GET",
+            "/byok/v1/models",
+            Some("changed-key"),
+            json!({})
+        )
+        .await
+        .0,
+        StatusCode::OK
+    );
+}
+
+async fn send(
+    router: axum::Router,
+    method: &str,
+    path: &str,
+    key: Option<&str>,
+    body: Value,
+) -> (StatusCode, String) {
+    let mut request = Request::builder()
+        .method(method)
+        .uri(path)
+        .header(header::CONTENT_TYPE, "application/json");
+    if let Some(key) = key {
+        request = request.header(header::AUTHORIZATION, format!("Bearer {key}"));
+    }
+    let response = router
+        .oneshot(request.body(Body::from(body.to_string())).unwrap())
+        .await
+        .unwrap();
+    let status = response.status();
+    let bytes = to_bytes(response.into_body(), 1024 * 1024).await.unwrap();
+    (status, String::from_utf8(bytes.to_vec()).unwrap())
+}
+
+#[tokio::test]
+async fn disabled_and_unauthorized_requests_cannot_list_models() {
+    let (router, _provider, store, _directory) = setup().await;
+    assert_eq!(
+        send(
+            router.clone(),
+            "GET",
+            "/byok/v1/models",
+            Some("secret"),
+            json!({})
+        )
+        .await
+        .0,
+        StatusCode::FORBIDDEN
+    );
+    store
+        .set_external_api_settings(ExternalApiSettings {
+            enabled: true,
+            api_key: "secret".into(),
+        })
+        .await
+        .unwrap();
+    assert_eq!(
+        send(router.clone(), "GET", "/byok/v1/models", None, json!({}))
+            .await
+            .0,
+        StatusCode::UNAUTHORIZED
+    );
+    assert_eq!(
+        send(
+            router.clone(),
+            "GET",
+            "/byok/v1/models",
+            Some("wrong"),
+            json!({})
+        )
+        .await
+        .0,
+        StatusCode::UNAUTHORIZED
+    );
+    let (status, body) = send(router, "GET", "/byok/v1/models", Some("secret"), json!({})).await;
+    assert_eq!(status, StatusCode::OK);
+    assert_eq!(
+        serde_json::from_str::<Value>(&body).unwrap()["data"][0]["id"],
+        "work/qwen/model"
+    );
+}
+
+#[tokio::test]
+async fn duplicate_public_model_ids_use_the_first_configured_model() {
+    let (router, provider, store, _directory) = setup().await;
+    let first = store.models().await.unwrap().remove(0);
+    let mut duplicate = model_input();
+    duplicate.sort_order = 1;
+    duplicate.display_name = "Backup".into();
+    duplicate.base_url = "https://backup.example.com/v1".into();
+    store.create_model(&duplicate).await.unwrap();
+    let mut distinct = model_input();
+    distinct.sort_order = 2;
+    distinct.model_id = "qwen/other".into();
+    store.create_model(&distinct).await.unwrap();
+    store
+        .set_external_api_settings(ExternalApiSettings {
+            enabled: true,
+            api_key: "secret".into(),
+        })
+        .await
+        .unwrap();
+
+    let (status, body) = send(
+        router.clone(),
+        "GET",
+        "/byok/v1/models",
+        Some("secret"),
+        json!({}),
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK, "{body}");
+    let models = serde_json::from_str::<Value>(&body).unwrap();
+    let ids = models["data"]
+        .as_array()
+        .unwrap()
+        .iter()
+        .map(|model| model["id"].as_str().unwrap())
+        .collect::<Vec<_>>();
+    assert_eq!(ids, ["work/qwen/model", "work/qwen/other"]);
+
+    provider.push(vec![
+        ModelEvent::TextDelta("ok".into()),
+        ModelEvent::Done(FinishReason::Stop),
+    ]);
+    let (status, body) = send(
+        router,
+        "POST",
+        "/byok/v1/chat/completions",
+        Some("secret"),
+        json!({"model":"work/qwen/model","messages":[{"role":"user","content":"hello"}]}),
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK, "{body}");
+    assert_eq!(provider.requests()[0].model.model_id, first.model_hash);
+}
+
+#[tokio::test]
+async fn all_three_protocols_use_the_public_model_id() {
+    let (router, provider, store, _directory) = setup().await;
+    store
+        .set_external_api_settings(ExternalApiSettings {
+            enabled: true,
+            api_key: "secret".into(),
+        })
+        .await
+        .unwrap();
+    for (path, body) in [
+        (
+            "/byok/v1/chat/completions",
+            json!({"model":"work/qwen/model","messages":[{"role":"user","content":"hello"}]}),
+        ),
+        (
+            "/byok/v1/responses",
+            json!({"model":"work/qwen/model","input":"hello"}),
+        ),
+        (
+            "/byok/v1/messages",
+            json!({"model":"work/qwen/model","max_tokens":100,"messages":[{"role":"user","content":"hello"}]}),
+        ),
+    ] {
+        provider.push(vec![
+            ModelEvent::TextStart,
+            ModelEvent::TextDelta("world".into()),
+            ModelEvent::TextEnd,
+            ModelEvent::Done(FinishReason::Stop),
+        ]);
+        let (status, response) = send(router.clone(), "POST", path, Some("secret"), body).await;
+        assert_eq!(status, StatusCode::OK, "{path}: {response}");
+        assert!(response.contains("world"), "{path}: {response}");
+    }
+    assert_eq!(provider.requests().len(), 3);
+    assert!(provider
+        .requests()
+        .iter()
+        .all(|request| request.model.model_id != "work/qwen/model"));
+}
+
+#[tokio::test]
+async fn streaming_chat_returns_incremental_sse_and_tool_calls() {
+    let (router, provider, store, _directory) = setup().await;
+    store
+        .set_external_api_settings(ExternalApiSettings {
+            enabled: true,
+            api_key: "secret".into(),
+        })
+        .await
+        .unwrap();
+    provider.push(vec![
+        ModelEvent::TextStart,
+        ModelEvent::TextDelta("hello".into()),
+        ModelEvent::TextEnd,
+        ModelEvent::ToolCallStart {
+            index: 0,
+            call_id: "call_1".into(),
+            name: "lookup".into(),
+        },
+        ModelEvent::ToolCallArgumentsDelta {
+            index: 0,
+            delta: "{\"q\":1}".into(),
+        },
+        ModelEvent::ToolCallEnd { index: 0 },
+        ModelEvent::Done(FinishReason::ToolUse),
+    ]);
+    let (status, body) = send(router, "POST", "/byok/v1/chat/completions", Some("secret"),
+        json!({"model":"work/qwen/model","stream":true,"messages":[{"role":"user","content":"hello"}]})).await;
+    assert_eq!(status, StatusCode::OK);
+    assert!(body.contains("chat.completion.chunk"));
+    assert!(body.contains("lookup"));
+    assert!(body.contains("tool_calls"));
+    assert!(body.contains("[DONE]"));
+}
+
+#[tokio::test]
+async fn chat_tool_result_keeps_the_assistant_function_name() {
+    let (router, provider, store, _directory) = setup().await;
+    store
+        .set_external_api_settings(ExternalApiSettings {
+            enabled: true,
+            api_key: "secret".into(),
+        })
+        .await
+        .unwrap();
+    provider.push(vec![
+        ModelEvent::TextDelta("done".into()),
+        ModelEvent::Done(FinishReason::Stop),
+    ]);
+    let body = json!({"model":"work/qwen/model","messages":[
+        {"role":"user","content":"find it"},
+        {"role":"assistant","tool_calls":[{"id":"call_1","type":"function","function":{"name":"lookup","arguments":"{\"q\":1}"}}]},
+        {"role":"tool","tool_call_id":"call_1","content":"found"}
+    ]});
+    assert_eq!(
+        send(
+            router,
+            "POST",
+            "/byok/v1/chat/completions",
+            Some("secret"),
+            body
+        )
+        .await
+        .0,
+        StatusCode::OK
+    );
+    let requests = provider.requests();
+    let ProjectedContent::ToolResult(result) = &requests[0].history[2].content else {
+        panic!("expected tool result");
+    };
+    assert_eq!(result.name, "lookup");
+}
+
+#[tokio::test]
+async fn responses_and_messages_stream_with_protocol_end_events() {
+    let (router, provider, store, _directory) = setup().await;
+    store
+        .set_external_api_settings(ExternalApiSettings {
+            enabled: true,
+            api_key: "secret".into(),
+        })
+        .await
+        .unwrap();
+    for (path, request, terminal) in [
+        (
+            "/byok/v1/responses",
+            json!({"model":"work/qwen/model","input":"hello","stream":true}),
+            "response.completed",
+        ),
+        (
+            "/byok/v1/messages",
+            json!({"model":"work/qwen/model","max_tokens":100,"messages":[{"role":"user","content":"hello"}],"stream":true}),
+            "message_stop",
+        ),
+    ] {
+        provider.push(vec![
+            ModelEvent::TextDelta("world".into()),
+            ModelEvent::Done(FinishReason::Stop),
+        ]);
+        let (status, body) = send(router.clone(), "POST", path, Some("secret"), request).await;
+        assert_eq!(status, StatusCode::OK);
+        assert!(body.contains(terminal), "{path}: {body}");
+    }
+}
+
+#[tokio::test]
+async fn responses_stream_emits_complete_text_and_tool_item_lifecycles() {
+    let (router, provider, store, _directory) = setup().await;
+    store
+        .set_external_api_settings(ExternalApiSettings {
+            enabled: true,
+            api_key: "secret".into(),
+        })
+        .await
+        .unwrap();
+    provider.push(vec![
+        ModelEvent::TextStart,
+        ModelEvent::TextDelta("hello".into()),
+        ModelEvent::TextEnd,
+        ModelEvent::ToolCallStart {
+            index: 0,
+            call_id: "call_1".into(),
+            name: "lookup".into(),
+        },
+        ModelEvent::ToolCallArgumentsDelta {
+            index: 0,
+            delta: "{\"q\":1}".into(),
+        },
+        ModelEvent::ToolCallEnd { index: 0 },
+        ModelEvent::Done(FinishReason::ToolUse),
+    ]);
+    let (status, body) = send(
+        router,
+        "POST",
+        "/byok/v1/responses",
+        Some("secret"),
+        json!({"model":"work/qwen/model","input":"hello","stream":true}),
+    )
+    .await;
+    assert_eq!(status, StatusCode::OK);
+    let events = body
+        .lines()
+        .filter_map(|line| line.strip_prefix("event: "))
+        .collect::<Vec<_>>();
+    assert_eq!(
+        events,
+        [
+            "response.created",
+            "response.in_progress",
+            "response.output_item.added",
+            "response.content_part.added",
+            "response.output_text.delta",
+            "response.output_text.done",
+            "response.content_part.done",
+            "response.output_item.done",
+            "response.output_item.added",
+            "response.function_call_arguments.delta",
+            "response.function_call_arguments.done",
+            "response.output_item.done",
+            "response.completed",
+        ]
+    );
+    assert!(body.contains("\"output_index\":1"), "{body}");
+}
+
+#[tokio::test]
+async fn messages_stream_closes_each_content_block_before_stopping() {
+    let (router, provider, store, _directory) = setup().await;
+    store
+        .set_external_api_settings(ExternalApiSettings {
+            enabled: true,
+            api_key: "secret".into(),
+        })
+        .await
+        .unwrap();
+    provider.push(vec![
+        ModelEvent::TextStart,
+        ModelEvent::TextDelta("hello".into()),
+        ModelEvent::TextEnd,
+        ModelEvent::ToolCallStart {
+            index: 0,
+            call_id: "call_1".into(),
+            name: "lookup".into(),
+        },
+        ModelEvent::ToolCallArgumentsDelta {
+            index: 0,
+            delta: "{\"q\":1}".into(),
+        },
+        ModelEvent::ToolCallEnd { index: 0 },
+        ModelEvent::Done(FinishReason::ToolUse),
+    ]);
+    let (status, body) = send(router, "POST", "/byok/v1/messages", Some("secret"),
+        json!({"model":"work/qwen/model","max_tokens":100,"messages":[{"role":"user","content":"hello"}],"stream":true})).await;
+    assert_eq!(status, StatusCode::OK);
+    let events = body
+        .lines()
+        .filter_map(|line| line.strip_prefix("event: "))
+        .collect::<Vec<_>>();
+    assert_eq!(
+        events,
+        [
+            "message_start",
+            "content_block_start",
+            "content_block_delta",
+            "content_block_stop",
+            "content_block_start",
+            "content_block_delta",
+            "content_block_stop",
+            "message_delta",
+            "message_stop",
+        ]
+    );
+    assert!(body.contains("\"index\":1"), "{body}");
+}
+
+#[tokio::test]
+async fn all_protocols_preserve_cached_usage_in_streaming_and_complete_responses() {
+    let (router, provider, store, _directory) = setup().await;
+    store
+        .set_external_api_settings(ExternalApiSettings {
+            enabled: true,
+            api_key: "secret".into(),
+        })
+        .await
+        .unwrap();
+    let usage = Usage {
+        input_tokens: Some(1_000),
+        context_input_tokens: Some(1_000),
+        output_tokens: Some(50),
+        total_tokens: Some(1_050),
+        cache_read_tokens: Some(800),
+        cache_write_tokens: Some(20),
+        reasoning_tokens: Some(10),
+    };
+    for (path, request, usage_pointer, cached_pointer, expected_input) in [
+        (
+            "/byok/v1/chat/completions",
+            json!({"model":"work/qwen/model","messages":[{"role":"user","content":"hello"}]}),
+            "/usage",
+            "/prompt_tokens_details/cached_tokens",
+            1_000,
+        ),
+        (
+            "/byok/v1/responses",
+            json!({"model":"work/qwen/model","input":"hello"}),
+            "/response/usage",
+            "/input_tokens_details/cached_tokens",
+            1_000,
+        ),
+        (
+            "/byok/v1/messages",
+            json!({"model":"work/qwen/model","max_tokens":100,"messages":[{"role":"user","content":"hello"}]}),
+            "/usage",
+            "/cache_read_input_tokens",
+            180,
+        ),
+    ] {
+        for stream in [false, true] {
+            provider.push(vec![
+                ModelEvent::TextDelta("world".into()),
+                ModelEvent::Usage(usage),
+                ModelEvent::Done(FinishReason::Stop),
+            ]);
+            let mut request = request.clone();
+            request["stream"] = json!(stream);
+            let (status, body) = send(router.clone(), "POST", path, Some("secret"), request).await;
+            assert_eq!(status, StatusCode::OK, "{path}: {body}");
+            let response = if stream {
+                body.lines()
+                    .filter_map(|line| line.strip_prefix("data: "))
+                    .filter_map(|line| serde_json::from_str::<Value>(line).ok())
+                    .find(|event| match path {
+                        "/byok/v1/chat/completions" => event.get("usage").is_some(),
+                        "/byok/v1/responses" => event["type"] == "response.completed",
+                        _ => event["type"] == "message_delta",
+                    })
+                    .unwrap_or_else(|| panic!("missing usage event in {path}: {body}"))
+            } else {
+                serde_json::from_str::<Value>(&body).unwrap()
+            };
+            let usage = response
+                .pointer(if stream { usage_pointer } else { "/usage" })
+                .unwrap();
+            assert_eq!(
+                usage.pointer(cached_pointer),
+                Some(&json!(800)),
+                "{path} stream={stream}: {body}"
+            );
+            let input_field = if path == "/byok/v1/chat/completions" {
+                "prompt_tokens"
+            } else {
+                "input_tokens"
+            };
+            assert_eq!(
+                usage[input_field], expected_input,
+                "{path} stream={stream}: {body}"
+            );
+            if path == "/byok/v1/messages" {
+                assert_eq!(usage["cache_creation_input_tokens"], 20, "{body}");
+            }
+            if stream && path == "/byok/v1/chat/completions" {
+                let finished = body.find("\"finish_reason\":\"stop\"").unwrap();
+                let usage_position = body.find("\"cached_tokens\":800").unwrap();
+                let done = body.find("[DONE]").unwrap();
+                assert!(finished < usage_position && usage_position < done, "{body}");
+            }
+        }
+    }
+}
+
+#[tokio::test]
+async fn all_entry_and_upstream_protocol_pairs_preserve_cache_usage() {
+    let (_directory, store) = fixtures::temp_store().await;
+    store.create_model(&model_input()).await.unwrap();
+    store
+        .set_external_api_settings(ExternalApiSettings {
+            enabled: true,
+            api_key: "secret".into(),
+        })
+        .await
+        .unwrap();
+    let runtime = PluginRuntime::managed().unwrap();
+    let plugins = PluginRegistry::managed(store.clone(), runtime, "0.1.0".into()).unwrap();
+    let fake = fake_provider::FakeProvider::default();
+    let inner = byok::router(store.clone(), plugins.clone(), Arc::new(fake.clone()), None);
+    let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let port = listener.local_addr().unwrap().port();
+    let server = tokio::spawn(async move { axum::serve(listener, inner).await.unwrap() });
+
+    for (order, group, model_type, endpoint) in [
+        (1, "bridge-chat", ModelType::OpenAi, OPENAI_CHAT_ENDPOINT),
+        (
+            2,
+            "bridge-responses",
+            ModelType::OpenAi,
+            OPENAI_RESPONSES_ENDPOINT,
+        ),
+        (3, "bridge-messages", ModelType::Anthropic, ""),
+    ] {
+        let mut model = model_input();
+        model.sort_order = order;
+        model.display_name = format!("Bridge {group}");
+        model.group_name = Some(group.into());
+        model.model_type = model_type;
+        model.openai_endpoint = endpoint.into();
+        model.base_url = format!("http://127.0.0.1:{port}/byok/v1");
+        model.model_id = "work/qwen/model".into();
+        model.api_key = "secret".into();
+        store.create_model(&model).await.unwrap();
+    }
+    let provider = ProviderRouter::new(
+        store.clone(),
+        plugins.clone(),
+        NetworkClients::new(store.clone()),
+        Duration::from_secs(10),
+        Duration::from_secs(10),
+    );
+    let outer = byok::router(
+        store.clone(),
+        plugins,
+        Arc::new(provider),
+        Some(byok::NativeForwarder::new(
+            store.clone(),
+            NetworkClients::new(store.clone()),
+            Duration::from_secs(10),
+            Duration::from_secs(10),
+        )),
+    );
+    for (path, request) in [
+        (
+            "/byok/v1/chat/completions",
+            json!({"messages":[{"role":"user","content":"hello"}],
+                "tools":[{"type":"function","function":{"name":"lookup","description":"Look up a value","parameters":{"type":"object","properties":{"q":{"type":"string"}}}}}]}),
+        ),
+        (
+            "/byok/v1/responses",
+            json!({"input":"hello",
+            "tools":[{"type":"function","name":"lookup","description":"Look up a value","parameters":{"type":"object","properties":{"q":{"type":"string"}}}}]}),
+        ),
+        (
+            "/byok/v1/messages",
+            json!({"max_tokens":100,"messages":[{"role":"user","content":"hello"}],
+                "tools":[{"name":"lookup","description":"Look up a value","input_schema":{"type":"object","properties":{"q":{"type":"string"}}}}]}),
+        ),
+    ] {
+        for group in ["bridge-chat", "bridge-responses", "bridge-messages"] {
+            for stream in [false, true] {
+                let prior_calls: HashSet<_> = store
+                    .llm_calls(100)
+                    .await
+                    .unwrap()
+                    .into_iter()
+                    .map(|call| call.call_id)
+                    .collect();
+                fake.push(vec![
+                    ModelEvent::TextStart,
+                    ModelEvent::TextDelta("world".into()),
+                    ModelEvent::TextEnd,
+                    ModelEvent::ToolCallStart {
+                        index: 0,
+                        call_id: "call_1".into(),
+                        name: "lookup".into(),
+                    },
+                    ModelEvent::ToolCallArgumentsDelta {
+                        index: 0,
+                        delta: "{\"q\":\"x\"}".into(),
+                    },
+                    ModelEvent::ToolCallEnd { index: 0 },
+                    ModelEvent::Usage(Usage {
+                        input_tokens: Some(1_000),
+                        context_input_tokens: Some(1_000),
+                        output_tokens: Some(50),
+                        total_tokens: Some(1_050),
+                        cache_read_tokens: Some(800),
+                        ..Usage::default()
+                    }),
+                    ModelEvent::Done(FinishReason::ToolUse),
+                ]);
+                let mut request = request.clone();
+                request["model"] = json!(format!("{group}/work/qwen/model"));
+                request["stream"] = json!(stream);
+                let (status, body) =
+                    send(outer.clone(), "POST", path, Some("secret"), request).await;
+                assert_eq!(
+                    status,
+                    StatusCode::OK,
+                    "{path} -> {group} stream={stream}: {body}"
+                );
+                assert!(
+                    body.contains("world"),
+                    "{path} -> {group} stream={stream}: {body}"
+                );
+                assert!(
+                    body.contains("lookup") && body.contains("call_1"),
+                    "{path} -> {group} stream={stream}: {body}"
+                );
+                let requests = fake.requests();
+                let forwarded = requests.last().unwrap();
+                assert_eq!(
+                    forwarded.prompt.tools.len(),
+                    1,
+                    "{path} -> {group} stream={stream}"
+                );
+                assert_eq!(
+                    forwarded.prompt.tools[0].name, "lookup",
+                    "{path} -> {group} stream={stream}"
+                );
+                let calls = store.llm_calls(100).await.unwrap();
+                let call = calls
+                    .iter()
+                    .find(|call| {
+                        call.display_name == format!("Bridge {group}")
+                            && !prior_calls.contains(&call.call_id)
+                    })
+                    .unwrap();
+                assert_eq!(
+                    call.cache_read_tokens,
+                    Some(800),
+                    "{path} -> {group} stream={stream}"
+                );
+            }
+        }
+    }
+    assert_eq!(fake.requests().len(), 18);
+    server.abort();
+}
+
+#[tokio::test]
+async fn matching_http_protocols_forward_native_requests_and_responses() {
+    let (directory, store) = fixtures::temp_store().await;
+    store
+        .set_external_api_settings(ExternalApiSettings {
+            enabled: true,
+            api_key: "secret".into(),
+        })
+        .await
+        .unwrap();
+    let runtime = PluginRuntime::managed().unwrap();
+    let plugins = PluginRegistry::managed(store.clone(), runtime, "0.1.0".into()).unwrap();
+    let (sender, mut receiver) = tokio::sync::mpsc::unbounded_channel::<(HeaderMap, Value)>();
+    let upstream = Router::new().route(
+        "/{*path}",
+        post(move |headers: HeaderMap, Json(body): Json<Value>| {
+            let sender = sender.clone();
+            async move {
+                sender.send((headers, body.clone())).unwrap();
+                if body["native_error"] == true {
+                    return (
+                        StatusCode::TOO_MANY_REQUESTS,
+                        Json(json!({"error":"native-rate-limit"})),
+                    )
+                        .into_response();
+                }
+                if body["stream"] == true {
+                    (
+                        [(header::CONTENT_TYPE, "text/event-stream")],
+                        "data: {\"native_marker\":\"untouched-stream\"}\n\n",
+                    )
+                        .into_response()
+                } else {
+                    Json(json!({"native_marker":"untouched-complete","echo":body})).into_response()
+                }
+            }
+        }),
+    );
+    let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
+    let port = listener.local_addr().unwrap().port();
+    let server = tokio::spawn(async move { axum::serve(listener, upstream).await.unwrap() });
+    for (order, group, model_type, endpoint, path, request) in [
+        (
+            1,
+            "chat",
+            ModelType::OpenAi,
+            OPENAI_CHAT_ENDPOINT,
+            "/byok/v1/chat/completions",
+            json!({"messages":[{"role":"user","content":"hi"}],"native_extension":{"keep":1}}),
+        ),
+        (
+            2,
+            "responses",
+            ModelType::OpenAi,
+            OPENAI_RESPONSES_ENDPOINT,
+            "/byok/v1/responses",
+            json!({"input":[{"type":"native_unsupported","value":1}],"native_extension":{"keep":2}}),
+        ),
+        (
+            3,
+            "messages",
+            ModelType::Anthropic,
+            "",
+            "/byok/v1/messages",
+            json!({"max_tokens":100,"messages":[{"role":"user","content":[{"type":"document","source":{"type":"url","url":"https://example.com"}}]}],"native_extension":{"keep":3}}),
+        ),
+    ] {
+        let mut model = model_input();
+        model.sort_order = order;
+        model.group_name = Some(group.into());
+        model.model_type = model_type;
+        model.openai_endpoint = endpoint.into();
+        model.base_url = format!("http://127.0.0.1:{port}/byok/v1");
+        model.model_id = "native-model".into();
+        store.create_model(&model).await.unwrap();
+        for stream in [false, true] {
+            let mut request = request.clone();
+            request["model"] = json!(format!("{group}/native-model"));
+            request["stream"] = json!(stream);
+            let (status, body) = send(
+                byok::router(
+                    store.clone(),
+                    plugins.clone(),
+                    Arc::new(fake_provider::FakeProvider::default()),
+                    Some(byok::NativeForwarder::new(
+                        store.clone(),
+                        NetworkClients::new(store.clone()),
+                        Duration::from_secs(10),
+                        Duration::from_secs(10),
+                    )),
+                ),
+                "POST",
+                path,
+                Some("secret"),
+                request.clone(),
+            )
+            .await;
+            assert_eq!(status, StatusCode::OK, "{path} stream={stream}: {body}");
+            if stream {
+                assert_eq!(body, "data: {\"native_marker\":\"untouched-stream\"}\n\n");
+            } else {
+                assert_eq!(
+                    serde_json::from_str::<Value>(&body).unwrap()["native_marker"],
+                    "untouched-complete"
+                );
+            }
+            let (upstream_headers, forwarded) = receiver.recv().await.unwrap();
+            request["model"] = json!("native-model");
+            assert_eq!(forwarded, request);
+            if model_type == ModelType::Anthropic {
+                assert_eq!(upstream_headers["x-api-key"], "upstream");
+                assert_eq!(upstream_headers["anthropic-version"], "2023-06-01");
+                assert!(!upstream_headers.contains_key(header::AUTHORIZATION));
+            } else {
+                assert_eq!(upstream_headers[header::AUTHORIZATION], "Bearer upstream");
+                assert!(!upstream_headers.contains_key("x-api-key"));
+            }
+        }
+    }
+    let mut error_request = json!({"model":"chat/native-model","messages":[],"native_error":true});
+    let (status, body) = send(
+        byok::router(
+            store.clone(),
+            plugins,
+            Arc::new(fake_provider::FakeProvider::default()),
+            Some(byok::NativeForwarder::new(
+                store.clone(),
+                NetworkClients::new(store.clone()),
+                Duration::from_secs(10),
+                Duration::from_secs(10),
+            )),
+        ),
+        "POST",
+        "/byok/v1/chat/completions",
+        Some("secret"),
+        error_request.clone(),
+    )
+    .await;
+    assert_eq!(status, StatusCode::TOO_MANY_REQUESTS);
+    assert_eq!(
+        serde_json::from_str::<Value>(&body).unwrap()["error"],
+        "native-rate-limit"
+    );
+    error_request["model"] = json!("native-model");
+    assert_eq!(receiver.recv().await.unwrap().1, error_request);
+    server.abort();
+    drop(directory);
+}