feat(core): port GitHub Copilot OAuth (#36336)

Co-authored-by: Dax Raad <d@ironbay.co>

packages/core/test/github-copilot/models.test.ts

@@ -0,0 +1,76 @@
+import { expect, test } from "bun:test"
+import { CopilotModels } from "@opencode-ai/core/github-copilot/models"
+import { ModelV2 } from "@opencode-ai/core/model"
+import { ProviderV2 } from "@opencode-ai/core/provider"
+
+test("defensively syncs advertised Copilot models", async () => {
+  const server = Bun.serve({
+    port: 0,
+    fetch: () =>
+      Response.json({
+        data: [
+          {
+            model_picker_enabled: true,
+            id: "gpt-5",
+            name: "GPT-5 remote",
+            version: "gpt-5-2026-06-01",
+            supported_endpoints: ["/responses"],
+            billing: {
+              token_prices: {
+                batch_size: 0,
+                default: { input_price: 10, output_price: 20, cache_price: 5 },
+              },
+            },
+            capabilities: {
+              family: "gpt",
+              limits: {
+                max_context_window_tokens: 200000,
+                max_output_tokens: 16384,
+                max_prompt_tokens: 180000,
+              },
+              supports: { tool_calls: true, reasoning_effort: ["low", "high"] },
+            },
+          },
+          {
+            model_picker_enabled: false,
+            id: "utility",
+            name: "Utility",
+            version: "utility-2026-06-01",
+            capabilities: {
+              family: "utility",
+              limits: { max_output_tokens: 1000, max_prompt_tokens: 8000 },
+              supports: { tool_calls: false },
+            },
+          },
+          { model_picker_enabled: true, id: "incomplete" },
+        ],
+      }),
+  })
+
+  try {
+    const existing = ModelV2.Info.make({
+      ...ModelV2.Info.empty(ProviderV2.ID.githubCopilot, ModelV2.ID.make("gpt-5")),
+      modelID: ModelV2.ID.make("gpt-5"),
+      name: "GPT-5 local",
+    })
+    const stale = ModelV2.Info.make({
+      ...ModelV2.Info.empty(ProviderV2.ID.githubCopilot, ModelV2.ID.make("stale")),
+      modelID: ModelV2.ID.make("stale"),
+    })
+    const models = await CopilotModels.get(server.url.origin, {}, [existing, stale])
+    const model = models.get(ModelV2.ID.make("gpt-5"))
+
+    expect(model?.name).toBe("GPT-5 local")
+    expect(model?.settings).toMatchObject({ baseURL: server.url.origin, endpoint: "responses" })
+    expect(model?.cost[0]).toMatchObject({ input: 0, output: 0, cache: { read: 0, write: 0 } })
+    expect(model?.variants.map((variant) => variant.id)).toEqual([
+      ModelV2.VariantID.make("low"),
+      ModelV2.VariantID.make("high"),
+    ])
+    expect(models.get(ModelV2.ID.make("utility"))?.enabled).toBe(false)
+    expect(models.has(ModelV2.ID.make("stale"))).toBe(false)
+    expect(models.has(ModelV2.ID.make("incomplete"))).toBe(false)
+  } finally {
+    await server.stop(true)
+  }
+})