Function build_e2b_python

catalog/code/:exec/python/backend.rs:233–263

Build the full Python script that gets sent to E2B's /execute endpoint. The function's return dict is rendered as the cell's last expression wrapped in `IPython.display.JSON(...)`. The Jupyter kernel emits it as a `result` event with the dict in its `json` field, so we never scrape stdout for it. Optional pip deps are installed via `!pip install` at the top.

(user_code: &str, deps_field: &str, input: &Value)

/// event with the dict in its `json` field, so we never scrape stdout for it.
/// Optional pip deps are installed via `!pip install` at the top.
fn build_e2b_python(user_code: &str, deps_field: &str, input: &Value) -> String {
    let (star_imports, prelude, body) = build_user_block(user_code, input);
    let pip_line = pip_install_line(deps_field);

    format!(
        r#"
import json as __weft_json__
from IPython.display import JSON as __weft_JSON__

{pip}
{star_imports}

{prelude}

def __weft_user_code__():
{body}

__weft_result__ = __weft_user_code__()
if __weft_result__ is None:
    __weft_result__ = {{}}
if not isinstance(__weft_result__, dict):
    raise ValueError("Code must return a dict with output port names as keys, got: " + str(type(__weft_result__)))

__weft_JSON__(__weft_result__)
"#,
        pip = pip_line,
        star_imports = star_imports,
        prelude = prelude,
        body = body,
    )
}

/// Build the Python script for local execution (no Jupyter, no IPython).
/// Returns a script that prints exactly one line `WEFT_RESULT_JSON=<json>` to