Payloads

Program text, call arguments, results and error bodies are off by default. They’re AI-written code and customer data, so you opt in rather than out.

codeMode({
  capabilities,
  capture: { values: true },
});

Captured

The program’s hash is always written, capture on or off. That’s how you tell two runs of the same program apart, and it’s what’s left when you withhold the text itself.

Size caps

Big values get cut:

capture: {
  values: true,
  cap: 8192,          // bytes written per value
  programCap: 32768,  // bytes written for the program
  measure: 1048576,   // bytes read to work out the real size and hash
}

When something gets cut, a note records what happened:

code_mode.capture  {"gen_ai.tool.call.result":{"truncated":true,"bytes":62240,"hash":"sha256:…"}}

So you still know the real size and can match it against the full value elsewhere. OpenTelemetry has no way to say “this value was shortened”, which is why the note exists.

Set your cap below whatever limits your SDK, collector and backend have. Better to cut it yourself and say so than to have something downstream cut it silently.

Unserializable

A value with a cycle in it, a getter that throws, a toJSON that blows up: these all get recorded as redacted rather than crashing anything.

code_mode.capture  {"gen_ai.tool.call.result":{"redacted":true}}

That matters more here than in most libraries, because the values come from AI-written code. Whatever the program returns, capturing it can cost you the value and never the call.

Two more things land here. A NaN or an infinity anywhere in a value redacts the whole value, since JSON has no way to write either and putting null there would turn a reading into a reading of nothing. And a single value far past your cap is refused rather than read, because serializing something enormous is work a program can ask for without limit.

A redacted note carries no bytes and no hash. Both describe an original the host never managed to serialize, so there is no honest number to report.

Redacted

Absent means you never captured that thing. It says nothing.

Redacted means you had it and removed it on purpose. That’s a real signal, so they’re different on the wire.

To keep a program’s hash without its text, the shape is: no code_mode.program.text, a present code_mode.program.hash, and a capture note saying redacted.

Privacy

Everything here is program-determined, so it all carries a P provenance label. If you’re sending traces somewhere you don’t fully control, values: false gives you the whole structure of a run, durations, outcomes, ordering, failures, with none of the content.