Crate trace_diff 

trace-diff

Diff two agent traces semantically.

A “step” is { type, key, payload }. The diff walks both traces in order; aligned positions are compared by (type, key). The result lists steps that are Added, Removed, or Changed. Timestamps and noisy ids are not compared.

Use this in agent regression suites: capture a baseline trace once, re-run the agent, diff the new trace against the baseline. Any Changed step is something worth looking at.

Example

use trace_diff::{diff, Step, Change};
use serde_json::json;

let base = vec![
    Step { kind: "tool_call".into(), key: "read".into(), payload: json!({"path": "a.txt"}) },
    Step { kind: "tool_call".into(), key: "write".into(), payload: json!({"path": "out.txt"}) },
];
let new = vec![
    Step { kind: "tool_call".into(), key: "read".into(), payload: json!({"path": "a.txt"}) },
    Step { kind: "tool_call".into(), key: "write".into(), payload: json!({"path": "out.NEW.txt"}) },
];
let changes = diff(&base, &new);
assert!(matches!(changes[0], Change::Changed { .. }));

Structs

Step

One step in a trace.

Enums

Change

A single change.

Functions

diff

Diff base against new. Returns one entry per detected change.