Module add_parameter 

Add-parameter recipe: insert a new parameter into a function signature and update all call sites.

Algorithm:

1. Parse file with tree-sitter; locate the function declaration named function_name.
2. Find the parameter list node; determine insertion byte position.
3. Build the parameter text for the definition (name + optional type annotation).
4. Find all call sites via the facts index (find_callers). Falls back to text search if the index is unavailable, with a warning.
5. At each call site: find the argument list; insert default_value at position.
6. Return a RefactoringPlan with one PlannedEdit per affected file.

Language support: Rust, TypeScript/JavaScript, Python. Node kinds by language:

• Rust: function_item → parameters, args in arguments
• Python: function_definition → parameters, args in argument_list
• JS/TS: function_declaration/function/method_definition/arrow_function → formal_parameters, args in arguments

Structs

AddParameterOutcome

Outcome of a successful add-parameter plan.

Functions

plan_add_parameter

Build an add-parameter plan without touching the filesystem.