Hmbown/CodeWhale · error

.context_window must be greater than 0

Error message

{name}.context_window must be greater than 0

What it means

Provider config validation rejects a context_window explicitly set to 0. Context windows must be positive (or left unset to use the default); zero is meaningless and would break token budgeting. Thrown by validate_provider_context_window at config.rs:4078.

Solutions

1. Set context_window to a positive integer matching the provider's real limit (e.g. 200000).
2. Remove the key entirely to use the library default.
3. Fix the upstream source (env var or script) that produced 0.

Example fix

// before
[providers.myprovider]
context_window = 0
// after
[providers.myprovider]
context_window = 200000

if let Some(w) = provider.context_window {
    if w == 0 { return Err("context_window must be > 0"); }
}

When it happens

Trigger: A provider entry in config has `context_window = 0` (only Some(0) triggers; None and positive values pass).

Common situations: Computing the window from an env/CLI value that defaulted to 0; copy-paste of a template with a placeholder 0; a script generating config where a lookup failed and yielded 0.

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

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• .model_context_windows. must be greater than 0
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AI-assisted analysis of Hmbown/CodeWhale@73e0f67d83 (2026-09-22). Data as JSON: /api/errors/1b0fa5b9c075925e. Report an issue: GitHub.

Appendix: source

Thrown at crates/tui/src/config.rs:4078

            ("providers.meta", &self.meta),
            ("providers.xai", &self.xai),
        ];
        for (name, config) in builtins {
            validate_provider_context_window(name, config.context_window)?;
            validate_model_context_windows(name, config.model_context_windows.as_ref())?;
        }
        for (name, config) in &self.custom {
            let name = format!("providers.{name}");
            validate_provider_context_window(&name, config.context_window)?;
            validate_model_context_windows(&name, config.model_context_windows.as_ref())?;
        }
        Ok(())
    }
}

fn validate_provider_context_window(name: &str, value: Option<u32>) -> Result<()> {
    if value == Some(0) {
        anyhow::bail!("{name}.context_window must be greater than 0");
    }
    Ok(())
}

fn validate_model_context_windows(
    name: &str,
    table: Option<&std::collections::BTreeMap<String, u32>>,
) -> Result<()> {
    if let Some(table) = table {
        for (model, window) in table {
            if *window == 0 {
                anyhow::bail!("{name}.model_context_windows.{model} must be greater than 0");
            }
        }
    }
    Ok(())
}

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