feat(provider): support responses api for @ai-sdk/openai-compatible providers

[scratchmex]

What does this PR do?

it supports the responses api for providers using @ai-sdk/openai-compatible. I used your wrapper for github copilot provider which exposes the .responses api. could not do it natively because @ai-sdk does not supports it, see vercel/ai#11970

I plan to add documentation about the new parameters once the approach is approved

closes #9628

How did you verify your code works?

set breakpoint in the lines changed and verifying the override for languageModel was working

bun run --inspect=ws://localhost:6499/ --cwd packages/opencode ./src/index.ts serve --port 4096
opencode attach http://localhost:4096

then tried the model several times and worked ok

config used

{
  "provider": {
    "customprovider": {
      "npm": "@ai-sdk/openai-compatible",
      "options": {
        "baseURL": "<URL>/litellm",
        "headers": {
          "client": "opencode",
        },
        "litellmProxy": true,
      },
      "models": {
        "customprovider/gpt-5-codex": {
          "name": "OpenAI GPT 5 codex",
          "options": {
            "responsesApiSupported": true,
            "store": false,
          },
        },
      }
    }
  }
}

the store: false is needed to avoid sending item_reference messages, here

opencode/packages/opencode/src/provider/sdk/openai-compatible/src/responses/convert-to-openai-responses-input.ts

Line 173 in 2e53697

input.push({ type: "item_reference", id: part.toolCallId })

opencode/packages/opencode/src/provider/sdk/openai-compatible/src/responses/convert-to-openai-responses-input.ts

Line 199 in 2e53697

input.push({ type: "item_reference", id: reasoningId })

otherwise you will get the error Zero Data Retention Organizations are incompatible with the Responses API. see openai/openai-agents-python#605 for context

[github-actions]

Hey! Your PR title support responses api for openai-compatible providers doesn't follow conventional commit format.

Please update it to start with one of:

• feat: or feat(scope): new feature
• fix: or fix(scope): bug fix
• docs: or docs(scope): documentation changes
• chore: or chore(scope): maintenance tasks
• refactor: or refactor(scope): code refactoring
• test: or test(scope): adding or updating tests

Where scope is the package name (e.g., app, desktop, opencode).

See CONTRIBUTING.md for details.

[github-actions]

The following comment was made by an LLM, it may be inaccurate:

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