Failed to update setting: invalid {key} '{value}'. Expected

Error message

Failed to update setting: invalid {key} '{value}'. Expected a number from 10 to 100.

What it means

Thrown by parse_percent_setting for percentage-style settings. The value is trimmed, one trailing '%' is stripped, parsed as f64, then required to lie within 10.0..=100.0. Parse failures and out-of-range values bail with the identical message, so the cause is ambiguous from the text alone.

Source

Thrown at crates/tui/src/settings.rs:2599

    let parsed = value
        .trim()
        .parse::<u16>()
        .map_err(|_| anyhow::anyhow!("Invalid {key} '{value}': expected {min}-{max}"))?;
    if !(min..=max).contains(&parsed) {
        anyhow::bail!("Invalid {key} '{value}': expected {min}-{max}");
    }
    Ok(parsed)
}

fn parse_percent_setting(key: &str, value: &str) -> Result<f64> {
    let trimmed = value.trim().trim_end_matches('%').trim();
    let percent = trimmed.parse::<f64>().map_err(|_| {
        anyhow::anyhow!(
            "Failed to update setting: invalid {key} '{value}'. Expected a number from 10 to 100."
        )
    })?;
    if !(10.0..=100.0).contains(&percent) {
        anyhow::bail!(
            "Failed to update setting: invalid {key} '{value}'. Expected a number from 10 to 100."
        );
    }
    Ok(percent)
}

fn normalize_mention_menu_behavior(value: &str) -> Result<String> {
    match value.trim().to_ascii_lowercase().as_str() {
        "fuzzy" | "default" => Ok("fuzzy".to_string()),
        "browser" | "browse" | "file-browser" | "file_browser" => Ok("browser".to_string()),
        _ => {
            anyhow::bail!(
                "Failed to update setting: invalid mention_menu_behavior '{value}'. Expected: fuzzy, browser."
            )
        }
    }
}

View on GitHub (pinned to 0c42157ee5)

Solutions

Send a number between 10 and 100 inclusive; a single trailing % is optional.
Use a dot for decimals, not a comma.
If you genuinely need below 10%, that is out of contract by design; use 10 or reconsider which setting you need.
Pre-validate in the caller: trim, strip one %, parse f64, range-check 10..=100.

Example fix

# before
:set context_percent 5%

# after
:set context_percent 10%

Defensive patterns

Strategy: validation

Validate before calling

fn valid_percent(v: &str) -> bool {
    let t = v.trim().trim_end_matches('%').trim();
    matches!(t.parse::<f64>(), Ok(p) if (10.0..=100.0).contains(&p))
}

Try / catch

match parse_percent_setting(key, value) {
    Err(err) if err.to_string().contains("number from 10 to 100") => clamp_or_reprompt(),
    other => other?,
}

Prevention

Strip one trailing '%' and use a dot decimal before submitting.
Treat sub-10 percentages as out of contract rather than retrying variations.
Validate percent fields in config UIs with the same 10..=100 window.

When it happens

Trigger: ':set context_percent 5' (below 10), ':set context_percent 150' (above 100), ':set context_percent abc', or a double percent '10%%' where only one trailing % is stripped and the second breaks the f64 parse.

Common situations: Users trying to reserve tiny contexts (5%), values above 100 assuming oversubscription works, locale-style decimal commas ('12,5'), and trailing junk after the number ('50 x').

Related errors

AI-assisted analysis of Hmbown/CodeWhale@0c42157ee5 (2026-08-20). Data as JSON: /api/errors/91b756c6d7bf8720. Report an issue: GitHub.