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

import { Effect } from "effect"
import { ModelV2 } from "../../model"
import { define } from "@opencode-ai/plugin/v2/effect"
import { ProviderV2 } from "../../provider"

function shouldUseResponses(modelID: string) {
  // Copilot supports Responses for GPT-5 class models, except mini variants
  // which still need the chat-completions endpoint.
  const match = /^gpt-(\d+)/.exec(modelID)
  if (!match) return false
  return Number(match[1]) >= 5 && !modelID.startsWith("gpt-5-mini")
}

export const GithubCopilotPlugin = define({
  id: "github-copilot",
  effect: Effect.fn(function* (ctx) {
    yield* ctx.catalog.transform(
      Effect.fn(function* (evt) {
        const item = evt.provider.get(ProviderV2.ID.githubCopilot)
        if (!item || !item.models.has(ModelV2.ID.make("gpt-5-chat-latest"))) return
        evt.model.update(item.provider.id, ModelV2.ID.make("gpt-5-chat-latest"), (model) => {
          // This chat-only alias conflicts with the Copilot GPT-5 Responses route,
          // so hide it only for Copilot rather than for every provider catalog.
          model.enabled = false
        })
      }),
    )
    yield* ctx.aisdk.hook(
      "sdk",
      Effect.fn(function* (evt) {
        if (evt.package !== "@ai-sdk/github-copilot") return
        const mod = yield* Effect.promise(() => import("../../github-copilot/copilot-provider"))
        evt.sdk = mod.createOpenaiCompatible(evt.options)
      }),
    )
    yield* ctx.aisdk.hook(
      "language",
      Effect.fn(function* (evt) {
        if (evt.model.providerID !== ProviderV2.ID.githubCopilot) return
        if (evt.sdk.responses === undefined && evt.sdk.chat === undefined) {
          evt.language = evt.sdk.languageModel(evt.model.api.id)
          return
        }
        evt.language = shouldUseResponses(evt.model.api.id)
          ? evt.sdk.responses(evt.model.api.id)
          : evt.sdk.chat(evt.model.api.id)
      }),
    )
  }),
})