fleet task ' ' metadata.coordination_contracts accepts at…

Error message

fleet task '{}' metadata.coordination_contracts accepts at most 16 entries

What it means

The `metadata.coordination_contracts` array exceeds the hard cap of 16 entries. The limit keeps the coordination surface of a fleet task small and auditable; entries beyond 16 are not silently dropped — the whole spec is rejected. Duplicate strings are deduplicated later, but the length check runs on the raw array before dedup.

Solutions

Trim the list to at most 16 entries, removing duplicates first so the cap counts unique contracts.
Consolidate fine-grained contracts into broader ones (e.g. one "ledger" instead of per-table entries).
If contracts are generated, cap the generator at 16 and log when it truncates.

Example fix

# before
[metadata]
coordination_contracts = ["a", "b", "c", ... 20 entries ...]

# after
[metadata]
coordination_contracts = ["a", "b", "c"]  # <= 16 unique entries

Defensive patterns

Strategy: validation

Validate before calling

const MAX_CONTRACTS: usize = 16;

fn contracts_within_limit(values: &[serde_json::Value]) -> bool {
    values.len() <= MAX_CONTRACTS
}

Prevention

Deduplicate contracts before counting — the runtime's cap applies to the raw array.
Model contracts as a small fixed enum/slug list, not an open-ended generated set.
Fail loudly in generators when truncation would be needed rather than silently exceeding 16.

When it happens

Trigger: A spec listing 17+ contract strings, including duplicates (dedup happens after the count check, so 20 entries with 3 duplicates still fails).

Common situations: Generators enumerating every queue/topic as a contract; accumulated contracts from merging several task templates.

Related errors

AI-assisted analysis of Hmbown/CodeWhale@0c42157ee5 (2026-08-20). Data as JSON: /api/errors/5f8affe74c15aa53. Report an issue: GitHub.

Appendix: source

Thrown at crates/tui/src/fleet/worker_runtime.rs:389

    Ok(if segments.is_empty() {
        ".".to_string()
    } else {
        segments.join("/")
    })
}

fn fleet_coordination_contracts(task_spec: &FleetTaskSpec) -> Result<Vec<String>> {
    let Some(value) = task_spec.metadata.get("coordination_contracts") else {
        return Ok(Vec::new());
    };
    let Some(values) = value.as_array() else {
        bail!(
            "fleet task '{}' metadata.coordination_contracts must be an array of strings",
            task_spec.id
        );
    };
    if values.len() > 16 {
        bail!(
            "fleet task '{}' metadata.coordination_contracts accepts at most 16 entries",
            task_spec.id
        );
    }
    let mut contracts = Vec::new();
    for value in values {
        let Some(value) = value.as_str() else {
            bail!(
                "fleet task '{}' metadata.coordination_contracts must contain only strings",
                task_spec.id
            );
        };
        let value = value.trim();
        if value.is_empty()
            || value.chars().count() > 128
            || value.chars().any(|ch| matches!(ch, '\0' | '\r' | '\n'))
        {
            bail!(

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