Compaction summary response was unusable: only whitespace or

Error message

Compaction summary response was unusable: only whitespace or punctuation was returned.

What it means

After trimming every non-alphanumeric edge character, nothing remains: the payload was whitespace, punctuation, or emoji only (crates/tui/src/compaction.rs:1137). is_alphanumeric keeps the check language-neutral for CJK; visually non-empty punctuation or emoji-only payloads are not usable checkpoints.

Source

Thrown at crates/tui/src/compaction.rs:1137

    prompt
}

fn validate_compaction_summary(summary: &str) -> Result<()> {
    let trimmed = summary.trim();
    if trimmed.is_empty() {
        anyhow::bail!("Compaction summary response was unusable: no text was returned.");
    }

    // Strip every non-word edge, not just ASCII punctuation. Providers can
    // return visually non-empty Unicode punctuation or emoji-only payloads;
    // neither is a usable continuation checkpoint. `is_alphanumeric` keeps
    // this language-neutral for CJK and other scripts without imposing a
    // prose-length heuristic.
    let normalized = trimmed
        .trim_matches(|ch: char| !ch.is_alphanumeric())
        .to_ascii_lowercase();
    if normalized.is_empty() {
        anyhow::bail!(
            "Compaction summary response was unusable: only whitespace or punctuation was returned."
        );
    }
    if matches!(
        normalized.as_str(),
        "no summary available"
            | "summary unavailable"
            | "no summary"
            | "n/a"
            | "na"
            | "not available"
            | "i cannot provide a summary"
            | "i can't provide a summary"
            | "unable to provide a summary"
    ) {
        anyhow::bail!("Compaction summary response was unusable: a placeholder was returned.");
    }
    Ok(())

View on GitHub (pinned to 8880682c63)

Solutions

Retry - punctuation-only outputs are usually one-off sampling artifacts
Lower or normalize the compaction sampling temperature
Switch the compaction model
Shorten the history being summarized so the model is not reduced to filler

Defensive patterns

Strategy: try-catch

Validate before calling

// Pre-check any summary text you produce yourself
fn has_word_chars(s: &str) -> bool {
    s.trim_matches(|c: char| !c.is_alphanumeric()).chars().any(|c| c.is_alphanumeric())
}

Type guard

fn is_punctuation_only_summary(msg: &str) -> bool {
    msg.contains("only whitespace or punctuation was returned")
}

Try / catch

match compact().await {
    Err(e) if is_punctuation_only_summary(&e.to_string()) => {
        lower_temperature();
        compact().await
    }
    r => r,
}

Prevention

Normalize sampling temperature for compaction requests
Detect degenerate filler early in pipelines by checking alphanumeric presence

When it happens

Trigger: The model answers with '...', a divider line of dashes, markdown asterisks, or emoji-only content; Unicode punctuation-only replies from CJK models.

Common situations: Models hedging with decorative output instead of summarizing; degenerate sampling settings (temperature extremes); prompt templates that elicit formatting-only responses.

Related errors

AI-assisted analysis of Hmbown/CodeWhale@8880682c63 (2026-08-16). Data as JSON: /api/errors/2ce809bc7dec50a2. Report an issue: GitHub.