claude-code-transcripts

Typed parser for Claude Code transcript JSONL files.

Claude Code writes one JSON object per line into ~/.claude/projects/<slug>/<session>.jsonl. This crate exposes strongly-typed Entry variants covering every line kind the current client emits (user, assistant, system, summary, attachments, progress, tool uses, tool results, usage blocks, cache tokens, etc.), plus a round-trip validator useful for catching schema drift when Claude Code ships new fields.

Install

cargo add claude-code-transcripts

Usage

use claude_code_transcripts::types::Entry;

let text = std::fs::read_to_string("session.jsonl")?;
for line in text.lines().filter(|l| !l.is_empty()) {
    let entry: Entry = serde_json::from_str(line)?;
    // match on entry variants …
}
# Ok::<(), Box<dyn std::error::Error>>(())

Round-trip validator

Parse every line of a transcript and diff the re-serialized JSON against the original to detect unknown fields:

let result = claude_code_transcripts::check_transcript(std::path::Path::new("session.jsonl"));
result.print_report();

Two examples ship in-tree:

cargo run --example check_one -- path/to/session.jsonl
cargo run --example check_all                             # scans ~/.claude/projects

License

Dual-licensed under MIT OR Apache-2.0.