workers-ai-provider: modelSettings not forwarded to inputs — reasoning_effort and chat_template_kwargs silently ignored

[alexander-zuev]

Problem

modelSettings passed to the provider (2nd arg of workersAi(modelId, modelSettings)) are forwarded to getRunOptions() which becomes the 3rd argument (options) of binding.run(model, inputs, options).

However, Cloudflare Workers AI parameters like reasoning_effort and chat_template_kwargs belong on the inputs level (2nd argument of binding.run()). buildRunInputs() only constructs inputs from AI SDK-mapped args (max_tokens, temperature, top_p, response_format, tools, tool_choice) and never includes anything from modelSettings.

This means these parameters are silently dropped:

const workersAi = createWorkersAI({ binding: env.AI })

// reasoning_effort ends up in runOptions (3rd arg), not inputs (2nd arg)
const model = workersAi('@cf/zai-org/glm-4.7-flash', {
  reasoning_effort: 'low',
})

// chat_template_kwargs also silently dropped
const model = workersAi('@cf/zai-org/glm-4.7-flash', {
  chat_template_kwargs: { enable_thinking: false },
})

Affected parameters

From @cloudflare/workers-types (ChatCompletionsCommonOptions):

• reasoning_effort — "low" | "medium" | "high" | null
• chat_template_kwargs — { enable_thinking?: boolean, clear_thinking?: boolean }

Both are typed on the inputs object and accepted by binding.run(), but the provider never puts them there.

Where it breaks

In workers-ai-provider@3.1.10:

• buildRunInputs() in workersai-chat-language-model.ts — hardcoded field list, no passthrough from settings
• getRunOptions() in workersai-chat-language-model.ts — rest-spreads settings into options (wrong destination for these params)

Impact

GLM-4.7-flash, Kimi K2.5/K2.6, and any other reasoning model on Workers AI cannot have reasoning controlled via the provider. In our case, GLM-4.7-flash burned all 16,384 output tokens on an infinite reasoning loop because reasoning_effort: 'low' was silently ignored, causing AI_NoOutputGeneratedError after exhausting retries.

Expected behavior

reasoning_effort and chat_template_kwargs from modelSettings should be included in the inputs payload passed to binding.run().

Versions

• workers-ai-provider@3.1.10
• ai@6.0.159
• @cloudflare/workers-types@4.20260418.1

[Specy]

I came across this issue when trying to disable thinking in Kimi models, once fixed it would also be nice to document in the docs as it's not mentioned currently