[Bug]: usage cost no longer included in response?

[jaimeiniesta]

Bug Description

In 1.0.0-rc.4 I could do this to get the usage cost for a Google Gemini request:

defp parse_response(response) do
  text = ReqLLM.Response.text(response)
  usage = ReqLLM.Response.usage(response)

  {:ok,
     %{
       text: text,
       total_tokens: usage.total_tokens,
       total_cost: usage.total_cost,
       model: response.model
     }}
end

but in 1.0.0-rc.5 I get this error:

** (KeyError) key :total_cost not found in: %{
       output_tokens: 1,
       input_tokens: 17,
       reasoning_tokens: 0,
       cached_tokens: 0,
       total_tokens: 18
     }. Did you mean:

           * :total_tokens

I don't see any reference in the changelog for this, has this been removed?

Steps to Reproduce

1. Get the usage from ReqLLM.Response.usage(response)
2. Try to get total_cost from it.

Expected Behavior

Return the total cost.

Actual Behavior

It doesn't include any costs.

Environment

• Package version: 1.0.0-rc.5
• Elixir 1.18.4
• Erlang/OTP 28

Additional Context

Previously (RC4) this worked without needing to run mix req_llm.model_sync. But this fails in RC5 even if I run that mix task.

I'm not sure then why is that mix task doing...

[mikehostetler]

@jaimeiniesta Thanks - this is a bug - I'll investigate and fix today

[mikehostetler]

Issue fixed in current version (1.0.0-rc.7). The total_cost field is now present in response.usage for Google Gemini models.

Verified with test script: https://github.com/agentjido/req_llm/blob/main/verify_issue_81.exs

Test output shows total_cost is calculated correctly:

usage = %{
  total_cost: 2.0e-6,
  input_tokens: 7,
  output_tokens: 2,
  input_cost: 1.0e-6,
  output_cost: 1.0e-6
}

The cost calculation was added in RC4 (line 137 of CHANGELOG.md) and continues to work in RC7. The issue reported in RC5 appears to have been resolved.

[jaimeiniesta]

@mikehostetler this issue is back on RC7, requests using model gemini-2.5-flash-lite don't return the total_cost.

[mikehostetler]

Thanks - I found and fixed this in #124

[jaimeiniesta]

Hi, this bug is back in v1.0.0 - gemini-2.5-flash-lite doesn't return the total cost.

[mikehostetler]

@jaimeiniesta Opened the issue again so we don't lose it

[kasvith]

Hi @mikehostetler i also noticed this issue when using models like gemini-2.5-flash-lite

[kasvith]

im taking a look at this

[ellie]

Noticed this missing for opus 4.5, happy to help if needed

[mikehostetler]

Thanks @ellie - this has been an annoying and persistent issue. Would love help if you can offer it!