sigoden/aichat · error · anyhow::Error

Invalid chunk_size

Error message

Invalid chunk_size

What it means

In the interactive RAG setup wizard, set_chunk_size prompts the user for a chunk size and parses it as usize. Any non-numeric (or unparsable) input fails validation at parse time with this generic error.

Solutions

1. Re-run the setup and enter a plain positive integer, e.g. 2000
2. Use the interactive prompt's validator feedback — input must be an integer
3. Edit the generated RAG config file directly to set chunk_size numerically

Example fix

// at the prompt
// before: chunk size: 2k
// after:  chunk size: 2000

fn valid_chunk_size(s: &str) -> bool { s.trim().parse::<usize>().is_ok() }

let cs: usize = prompt_and_parse("chunk size").map_err(|_| {
    eprintln!("Enter a plain positive integer, e.g. 2000"); retry()
})?;

When it happens

Trigger: Entering a value that doesn't parse as usize at the 'chunk size' prompt during rag create_config (e.g. '1k', '10.5', '', 'abc').

Common situations: Typing suffixed numbers like '512b' or '1k'; pasting values with whitespace/units; accidental non-digit input.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• Invalid chunk_overlay
• Unknown RAG
• No RAG
• No models
• Unknown client

AI-assisted analysis of sigoden/aichat@82976d349a (2026-09-09). Data as JSON: /api/errors/42de5e557cf7d747. Report an issue: GitHub.

Appendix: source

Thrown at src/rag/mod.rs:903

    let default_value = model.default_chunk_size().to_string();
    let help_message = model
        .max_tokens_per_chunk()
        .map(|v| format!("The model's max_tokens is {v}"));

    let mut text = Text::new("Set chunk size:")
        .with_default(&default_value)
        .with_validator(move |text: &str| {
            let out = match text.parse::<usize>() {
                Ok(_) => Validation::Valid,
                Err(_) => Validation::Invalid("Must be a integer".into()),
            };
            Ok(out)
        });
    if let Some(help_message) = &help_message {
        text = text.with_help_message(help_message);
    }
    let value = text.prompt()?;
    value.parse().map_err(|_| anyhow!("Invalid chunk_size"))
}

fn set_chunk_overlay(default_value: usize) -> Result<usize> {
    let value = Text::new("Set chunk overlay:")
        .with_default(&default_value.to_string())
        .with_validator(move |text: &str| {
            let out = match text.parse::<usize>() {
                Ok(_) => Validation::Valid,
                Err(_) => Validation::Invalid("Must be a integer".into()),
            };
            Ok(out)
        })
        .prompt()?;
    value.parse().map_err(|_| anyhow!("Invalid chunk_overlay"))
}

fn add_documents() -> Result<Vec<String>> {
    let text = Text::new("Add documents:")

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