unicity-aos/aos-ce · warning

meta-harness: malformed hook request

Error message

meta-harness: malformed hook request: {error}

What it means

The meta-harness capsule's on_message_received interceptor expects a JSON payload deserializable into HookRequest. If serde_json::from_value fails, the hook request is malformed; the capsule logs this warning and returns Ok(()) (swallowing the error) so the host turn proceeds without reflection context.

Solutions

1. Log/inspect the raw payload and compare it to the HookRequest struct fields; fix the producer to emit the expected shape.
2. Update the HookRequest struct (serde attributes, Option fields) to match the current host payload schema.
3. Ensure capsule and host versions are aligned so the interceptor contract matches.
4. If the payload is user-supplied, validate it before registering the interceptor.

Example fix

// before
pub fn on_message_received(&self, payload: serde_json::Value) -> Result<(), SysError> {
    let request: HookRequest = serde_json::from_value(payload)?; // mismatch on shape
// after
pub fn on_message_received(&self, payload: serde_json::Value) -> Result<(), SysError> {
    // align payload with HookRequest: { "correlation_id": "...", "payload": "..." }
    let request: HookRequest = serde_json::from_value(payload)?;

function isValidHookRequest(payload) {
  return typeof payload === 'object' && payload !== null &&
    typeof payload.correlation_id === 'string' &&
    typeof payload.payload === 'string';
}

fn is_hook_request(v: &serde_json::Value) -> bool {
    v.get("correlation_id").map_or(false, |c| c.is_string())
        && v.get("payload").map_or(false, |p| p.is_string())
}

let request: HookRequest = match serde_json::from_value(payload) {
    Ok(r) => r,
    Err(e) => { log::warn("malformed hook request: {e}"); return Ok(()); }
};

When it happens

Trigger: on_message_received is invoked with a payload that is not valid JSON for HookRequest — missing required fields, wrong types (e.g., correlation_id not a string), or a completely different payload shape from the interceptor dispatcher.

Common situations: Host version emitting a changed interceptor payload schema; another interceptor or plugin forwarding the wrong payload; hand-crafted test payloads missing fields.

Understand the failure class

Background: "failed to unmarshal" / json.Unmarshal errors: why parsing a response into a Go struct fails and how to fix it — this error's family across 23 libraries.

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• meta-harness: malformed canonical payload
• Failed to parse from prompt builder
• failed to deserialize IPC message payload
• failed to deserialize compaction response payload
• canonical document exceeds bound

AI-assisted analysis of unicity-aos/aos-ce@f6f22024fb (2026-09-13). Data as JSON: /api/errors/865f78ce75a353d4. Report an issue: GitHub.

Appendix: source

Thrown at capsules/capsule-meta-harness/src/lib.rs:65

        "off" => Ok(None),
        other => {
            log::warn(format!(
                "meta-harness: unknown activation mode '{other}', using adaptive"
            ));
            Ok(Some(ADAPTIVE_CONTEXT))
        }
    }
}

#[capsule]
impl MetaHarness {
    /// Add private same-turn reflection context to an exact host prompt turn.
    #[astrid::interceptor("on_message_received")]
    pub fn on_message_received(&self, payload: serde_json::Value) -> Result<(), SysError> {
        let request: HookRequest = match serde_json::from_value(payload) {
            Ok(request) => request,
            Err(error) => {
                log::warn(format!("meta-harness: malformed hook request: {error}"));
                return Ok(());
            }
        };
        let Some(correlation_id) = request.correlation_id else {
            return Ok(());
        };
        if !is_correlation(&correlation_id) {
            log::warn("meta-harness: ignored unroutable hook correlation");
            return Ok(());
        }
        let canonical: CanonicalHostPayload = match serde_json::from_str(&request.payload) {
            Ok(canonical) => canonical,
            Err(error) => {
                log::warn(format!(
                    "meta-harness: malformed canonical payload: {error}"
                ));
                return Ok(());
            }

View on GitHub (pinned to f6f22024fb)