unicity-aos/aos-ce · warning

capability check failed for

Error message

capability check failed for {uuid}: {e}, denying

What it means

capsule-prompt-builder checks, per source_id, whether the source has the 'allow_prompt_injection' capability via capabilities::check. If the check itself errors (as opposed to returning false), the result is denied (fail-closed), cached as false, and this warning is logged by fire_before_prompt_build during assemble.

Solutions

1. Read the {e} detail and fix the capability backend availability or registration for that uuid.
2. Register the source capsule/uuid and grant 'allow_prompt_injection' explicitly if it should be allowed.
3. Clear the cached false entry (cache lives per assemble run) after fixing the backend and retry.
4. Confirm fail-closed is intended; if the source doesn't need injection, the warning can be ignored.

Example fix

// before
capabilities::check(uuid, "allow_prompt_injection")
    .inspect_err(|e| {
        runtime_log::warn(format!("capability check failed for {uuid}: {e}, denying"));
    })
    .unwrap_or(false)
// after
// register uuid in the capability store, then:
capabilities::check(uuid, "allow_prompt_injection")
    .inspect_err(|e| {
        runtime_log::warn(format!("capability check failed for {uuid}: {e}, denying"));
    })
    .unwrap_or(false) // now returns Ok(true) for granted sources

// check capability registration before assemble
const registered = await capabilities.exists(uuid);
if (!registered) throw new Error('source not registered: ' + uuid);

capabilities::check(uuid, "allow_prompt_injection")
    .inspect_err(|e| runtime_log::warn("capability check failed for {uuid}: {e}, denying"))
    .unwrap_or(false)

When it happens

Trigger: capabilities::check(uuid, "allow_prompt_injection") returns Err while building the per-uuid cache in fire_before_prompt_build — capability service unavailable, unknown uuid, or backend error resolving the source's capabilities.

Common situations: Capability store/registry outage; source uuid not yet registered; stale source_id from a removed capsule; permission configuration not yet propagated.

Understand the failure class

Background: Permission denied / not authorized / 403 Forbidden: access-control rejections when the caller lacks the required role, grant, or ownership — this error's family across 18 libraries.

Related errors

• ingress pending read error for source_id
• grant pending read error for capsule_id

AI-assisted analysis of unicity-aos/aos-ce@f6f22024fb (2026-09-13). Data as JSON: /api/errors/0657bc74cd22521e. Report an issue: GitHub.

Appendix: source

Thrown at capsules/capsule-prompt-builder/src/lib.rs:435

    // sub drops here, releasing the kernel-side subscription.

    runtime_log::info(format!(
        "Collected {} hook responses for request {}",
        sourced_responses.len(),
        request.request_id
    ));

    // Cache capability results per-UUID to avoid redundant host function calls.
    // Multiple hook responses can come from the same capsule.
    let mut cache = std::collections::HashMap::<String, bool>::new();
    filter_by_permission(sourced_responses, |source_id| {
        let Some(uuid) = source_id else {
            return false;
        };
        *cache.entry(uuid.to_owned()).or_insert_with(|| {
            capabilities::check(uuid, "allow_prompt_injection")
                .inspect_err(|e| {
                    runtime_log::warn(format!("capability check failed for {uuid}: {e}, denying"));
                })
                .unwrap_or(false)
        })
    })
}

/// Parse a single IPC message and extract hook responses with source capsule IDs.
fn parse_hook_message(msg: &ipc::Message) -> Option<Vec<SourcedHookResponse>> {
    let payload: serde_json::Value = match serde_json::from_str(&msg.payload) {
        Ok(v) => v,
        Err(e) => {
            runtime_log::warn(format!("failed to deserialize hook response payload: {e}"));
            return None;
        }
    };

    let source_id = if msg.source_id.is_empty() {
        None

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