affaan-m/ECC · error

at least one explicit seed is required

Error message

at least one explicit seed is required

What it means

evaluate_paired runs the evaluator on a candidate and baseline over an explicit list of seeds for paired comparison. This error is thrown when the seeds slice is empty, since a paired statistical comparison requires at least one explicit seed to sample. The library refuses to invent default seeds.

Solutions

1. Pass a non-empty seed list, e.g. &[1, 2, 3, ...], with at least one u64 seed.
2. If seeds come from config, provide a default seed set when the config value is missing or empty.
3. Validate seeds before calling: bail early in your own code if seeds.is_empty().
4. Check the code path that builds the seeds vector to see why it produced zero entries.

Example fix

// before
let seeds: Vec<u64> = config.seeds.clone(); // empty if unset
let samples = evaluate_paired(&mut eval, "cand", "base", &seeds)?; // bails

// after
let seeds: Vec<u64> = if config.seeds.is_empty() { vec![1, 2, 3, 4, 5] } else { config.seeds.clone() };
assert!(!seeds.is_empty());
let samples = evaluate_paired(&mut eval, "cand", "base", &seeds)?;

if seeds.is_empty() {
    return Err("at least one explicit seed is required");
}
if seeds.len() > 10_000 {
    return Err("seed count exceeds 10000");
}

When it happens

Trigger: Calling evaluate_paired(evaluator, candidate_id, baseline_id, &[]) with an empty seeds array, typically because the seed list was built from an empty config collection or a failed parse.

Common situations: Seeds loaded from a config/env var that is unset or empty; a filter accidentally removing all seeds; CLI flag for seeds not provided so the vec stays empty; refactoring that dropped the default seed list.

Understand the failure class

Background: "must not be empty", "cannot be empty" — required-field validation errors across open-source libraries — this error's family across 41 libraries.

Related errors

• At least one guided harness must be selected
• at least one non-empty
• at least one placement is required
• At least one video is required
• commit message cannot be empty

AI-assisted analysis of affaan-m/ECC@8321021c54 (2026-09-16). Data as JSON: /api/errors/7f859db42a4dfb3c. Report an issue: GitHub.

Appendix: source

Thrown at ecc2/src/harness_eval.rs:467

        Ok(self.health_ok)
    }
}

#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub struct PairedSample {
    pub seed: u64,
    pub candidate_score: f64,
    pub baseline_score: f64,
}

pub fn evaluate_paired(
    evaluator: &mut dyn Evaluator,
    candidate_id: &str,
    baseline_id: &str,
    seeds: &[u64],
) -> Result<Vec<PairedSample>> {
    if seeds.is_empty() {
        bail!("at least one explicit seed is required");
    }
    if seeds.len() > 10_000 {
        bail!("seed count exceeds 10000");
    }
    if seeds.iter().copied().collect::<BTreeSet<_>>().len() != seeds.len() {
        bail!("seeds must be unique");
    }
    seeds
        .iter()
        .map(|seed| {
            Ok(PairedSample {
                seed: *seed,
                candidate_score: evaluator.evaluate(candidate_id, *seed)?,
                baseline_score: evaluator.evaluate(baseline_id, *seed)?,
            })
        })
        .collect()
}

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