BoundaryML/baml · error

value metadata omitted codec

Error message

value metadata omitted codec

What it means

ValueMetadataV1.protobuf carried codec == Unspecified, meaning the writer never set which codec encoded the value (required: BamlOutboundValue). The TryFrom<crate::value::pb::ValueMetadataV1> conversion for the internal record rejects any metadata lacking an explicit codec because the decoder cannot know how to interpret the payload. It is a strict validation error (io::ErrorKind::InvalidData).

Source

Thrown at baml_language/crates/bex_events/src/value/record.rs:155

    pub timestamp_ms: u64,
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub enum ValueFileRecord {
    LogEvent(LogRecord),
    CaptureLoss(CaptureLossRecord),
    RunStarted(RunStartedRecord),
    RunCompleted(RunCompletedRecord),
}

impl TryFrom<crate::value::pb::ValueMetadataV1> for ValueRef {
    type Error = io::Error;

    fn try_from(metadata: crate::value::pb::ValueMetadataV1) -> Result<Self, Self::Error> {
        let codec = match metadata.codec() {
            crate::value::pb::ValueCodec::BamlOutboundValue => ValueCodec::BamlOutboundValue,
            crate::value::pb::ValueCodec::Unspecified => {
                return Err(io::Error::new(
                    io::ErrorKind::InvalidData,
                    "value metadata omitted codec",
                ));
            }
        };
        let availability = match metadata.availability() {
            crate::value::pb::ValueAvailability::Pending => ValueAvailability::Pending,
            crate::value::pb::ValueAvailability::Available => ValueAvailability::Available,
            crate::value::pb::ValueAvailability::Missing => ValueAvailability::Missing,
            crate::value::pb::ValueAvailability::Omitted => ValueAvailability::Omitted,
            crate::value::pb::ValueAvailability::Lost => ValueAvailability::Lost,
            crate::value::pb::ValueAvailability::Unspecified => {
                return Err(io::Error::new(
                    io::ErrorKind::InvalidData,
                    "value metadata omitted availability",
                ));
            }
        };

View on GitHub (pinned to bd85ce9dee)

Solutions

1. Upgrade or align the producer so it always sets codec = BamlOutboundValue before writing
2. If constructing the proto manually, call the codec setter (value.codec = ValueCodec::BamlOutboundValue as i32)
3. Reject/repair affected records at ingest time with a default codec if you know all data is BamlOutboundValue
4. Check writer version in the stream header and route old streams through a migration path

Example fix

// before
let mut md = pb::ValueMetadataV1::default();
md.availability = ...
// after
let mut md = pb::ValueMetadataV1::default();
md.codec = pb::ValueCodec::BamlOutboundValue.into();
md.availability = ...

if md.codec() == pb::ValueCodec::Unspecified { return Err("codec unset"); }

fn has_codec(md: &pb::ValueMetadataV1) -> bool { md.codec() != pb::ValueCodec::Unspecified }

match ValueRecord::try_from(md) { Ok(r) => Some(r), Err(e) if e.to_string().contains("omitted codec") => default_codec_record(md), Err(e) => return Err(e) }

When it happens

Trigger: Decoding a ValueMetadataV1 message whose codec field was left at the proto3 default (Unspecified) — e.g. produced by old writer code before the codec field existed, or a message constructed by hand in tests without setting codec.

Common situations: Mixing writer/reader versions across a schema migration, manually constructing pb::ValueMetadataV1 in tests or tools and forgetting .set_codec(), or a proxy/transform layer that rebuilds the proto and drops the field.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• value metadata omitted availability
• capture loss omitted kind
• capture loss omitted reason
• body record omitted log metadata
• original size does not fit usize

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/3f4c8d40c75ca68a. Report an issue: GitHub.