fix(provider): remove LiteLLM workarounds ported upstream, requires LiteLLM v1.85.0-rc.2+

[Sameerlite]

Summary

Removes OpenCode-side LiteLLM workarounds now handled in LiteLLM.

Fixes #21346

Changes

• transform.ts: Set reasoningSummary: "auto" for non–gpt-5-pro GPT‑5 models for all SDK packages, including @ai-sdk/openai-compatible
• llm.ts: Inject the _noop compat tool only for GitHub Copilot. LiteLLM detection and the litellmProxy provider option are removed.

Upstream

• fix(openai): route reasoningSummary for gpt-5.4+ chat without tools to Responses API BerriAI/litellm#27618 — OpenAI / reasoningSummary routing for GPT‑5.4+ chat without tools
• fix(anthropic): inject dummy tool without modify_params BerriAI/litellm#27620 — Anthropic dummy tool without modify_params

Verification

bun test test/provider/transform.test.ts test/session/llm.test.ts (from packages/opencode)

Both these issue fixes from Litellm side have made it to v1.85.0-rc.2.

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[rekram1-node]

lgtm so far, whenever it's ready ill merge it

Thanks!

[Sameerlite]

@rekram1-node let me know if this good to be merged. Only concern is that for this to work, user needs to use litellm with v1.85.0-rc.2+. If you can let me know any docs i need to update or if this can be mentioned in the release notes

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[KnutZuidema]

@rekram1-node this indeed breaks my usage, since I'm using a LiteLLM proxy which I do not directly control with a lower version.

Is there any reason to remove the handling for LiteLLM? I understand wanting to keep workarounds and tech debt to a minimum, but removing this workaround means OpenCode is broken when used with a LiteLLM provider version less than v1.85.0-rc.2+.

IMO, this change should be reverted.

[denisrosca]

same issue as @KnutZuidema
It's a bit premature to remove workarounds until most of the LiteLLM proxy had time to upgrade.

[rekram1-node]

Thats fair, im not as familiar with litellm so I was generally trusting the makers of it here, but given there have been a few issues ill add back this functionality in the interim but as a pure plugin which should be possible (will be enabled out of the box and should work exact same as this previously did)