fix(opencode): discover Copilot API endpoint

packages/opencode/src/plugin/github-copilot/copilot.ts

@@ -8,6 +8,7 @@ import { MessageV2 } from "@/session/message-v2"
 
 const CLIENT_ID = "Ov23li8tweQw6odWQebz"
 const API_VERSION = "2026-06-01"
+const USER_API_VERSION = "2025-04-01"
 const UTILITY_MODELS = ["gpt-5.4-nano", "gpt-4.1", "gpt-4o", "gpt-4o-mini"]
 // Add a small safety buffer when polling to avoid hitting the server
 // slightly too early due to clock skew / timer drift.
@@ -66,9 +67,28 @@ export async function CopilotAuthPlugin(input: PluginInput): Promise<Hooks> {
         }
 
         const auth = ctx.auth
+        const fallback = base(auth.enterpriseUrl)
+        const url = await fetch(
+          `${auth.enterpriseUrl ? `https://api.${normalizeDomain(auth.enterpriseUrl)}` : "https://api.github.com"}/copilot_internal/user`,
+          {
+            headers: {
+              Accept: "application/json",
+              Authorization: `Bearer ${auth.refresh}`,
+              "X-GitHub-Api-Version": USER_API_VERSION,
+            },
+            signal: AbortSignal.timeout(5_000),
+          },
+        )
+          .then(async (response) => {
+            if (!response.ok) return fallback
+            const result = (await response.json()) as { endpoints?: { api?: unknown } }
+            const endpoint = result.endpoints?.api
+            return typeof endpoint === "string" && endpoint ? endpoint.replace(/\/+$/, "") : fallback
+          })
+          .catch(() => fallback)
 
         return CopilotModels.get(
-          base(auth.enterpriseUrl),
+          url,
           {
             ...(provider.options?.headers as Record<string, string> | undefined),
             Authorization: `Bearer ${auth.refresh}`,
@@ -85,9 +105,7 @@ export async function CopilotAuthPlugin(input: PluginInput): Promise<Hooks> {
           })
           .catch((error) => {
             models = {}
-            return Object.fromEntries(
-              Object.entries(provider.models).map(([id, model]) => [id, fix(model, base(auth.enterpriseUrl))]),
-            )
+            return Object.fromEntries(Object.entries(provider.models).map(([id, model]) => [id, fix(model, url)]))
           })
       },
     },
@@ -187,17 +205,17 @@ export async function CopilotAuthPlugin(input: PluginInput): Promise<Hooks> {
             {
               type: "select",
               key: "deploymentType",
-              message: "Select GitHub deployment type",
+              message: "Select where your GitHub account is hosted",
               options: [
                 {
                   label: "GitHub.com",
                   value: "github.com",
-                  hint: "Public",
+                  hint: "Including Copilot Business or Enterprise",
                 },
                 {
-                  label: "GitHub Enterprise",
+                  label: "GitHub Enterprise host",
                   value: "enterprise",
-                  hint: "Data residency or self-hosted",
+                  hint: "GHE.com or self-hosted",
                 },
               ],
             },

packages/opencode/test/plugin/github-copilot-models.test.ts

@@ -422,3 +422,60 @@ test("remaps fallback oauth model urls to the enterprise host", async () => {
   expect(models.claude.api.url).toBe("https://copilot-api.ghe.example.com")
   expect(models.claude.api.npm).toBe("@ai-sdk/github-copilot")
 })
+
+test("uses the account-specific Copilot API endpoint", async () => {
+  const requests: string[] = []
+  globalThis.fetch = mock((input: RequestInfo | URL) => {
+    const url = input instanceof URL ? input.href : typeof input === "string" ? input : input.url
+    requests.push(url)
+    if (url === "https://api.github.com/copilot_internal/user") {
+      return Promise.resolve(
+        new Response(JSON.stringify({ endpoints: { api: "https://api.business.githubcopilot.com/" } })),
+      )
+    }
+    return Promise.reject(new Error("timeout"))
+  }) as unknown as typeof fetch
+
+  const hooks = await CopilotAuthPlugin({
+    client: {} as never,
+    project: {} as never,
+    directory: "",
+    worktree: "",
+    experimental_workspace: {
+      register() {},
+    },
+    serverUrl: new URL("https://example.com"),
+    $: {} as never,
+  })
+
+  const models = await hooks.provider!.models!(
+    {
+      id: "github-copilot",
+      models: {
+        claude: {
+          id: "claude",
+          providerID: "github-copilot",
+          api: {
+            id: "claude-sonnet-4.5",
+            url: "https://api.githubcopilot.com/v1",
+            npm: "@ai-sdk/anthropic",
+          },
+        },
+      },
+    } as never,
+    {
+      auth: {
+        type: "oauth",
+        refresh: "token",
+        access: "token",
+        expires: Date.now() + 60_000,
+      } as never,
+    },
+  )
+
+  expect(requests).toEqual([
+    "https://api.github.com/copilot_internal/user",
+    "https://api.business.githubcopilot.com/models",
+  ])
+  expect(models.claude.api.url).toBe("https://api.business.githubcopilot.com")
+})