gemini-cli - 💡(How to fix) Fix Code generation inserts new parameters in the middle of existing function signatures, breaking all callers

What happened?

Title: Code generation inserts new parameters in the middle of existing function signatures, breaking all callers

Description: When asked to add a new parameter to an existing function, Gemini CLI inserts it between existing positional arguments instead of appending it to the end. Since all existing callers use positional arguments, every subsequent parameter shifts by one position.

Example: Original signature:

def send_message(agentToolNames, middlewareNames, skillNames, modelName, subagentModelName, thinkEnabled)

Requested: Add pdfFormToolNames as a new parameter.

Gemini output:

def send_message(agentToolNames, pdfFormToolNames, middlewareNames, skillNames, modelName, subagentModelName, thinkEnabled)

Result — all existing callers now pass wrong values:

middlewareNames ← receives skillNames
skillNames      ← receives modelName
modelName       ← receives subagentModelName
subagentModel   ← receives thinkEnabled (false)

This caused Pydantic validation errors across the entire chat system (false is not a string, 128000 is not a boolean).

Expected behavior: New optional parameters are appended to the end of the signature to preserve backward compatibility with all existing callers.

Project context: FastAPI + LangChain + React, ~40,000 lines. The instruction explicitly stated to append the parameter to the end.

Impact: Critical — entire frontend non-functional until manually corrected.

I am no longer using Gemini CLI for production work. These issues are documented here for the benefit of other developers and the Gemini engineering team.

What did you expect to happen?

Nothing

Client information

Run gemini to enter the interactive CLI, then run the /about command.

> /about
# paste output here

Login information

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Anything else we need to know?

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