Trajectory: A Standard Format for Agent Experience Data

gist

Letta introduces Trajectory, an open-source format that converts sessions from Codex, Claude Code, Letta Code, and other agent harnesses into a common sequence of messages, reasoning, tool calls, and results. It is optimized for agents learning from prior work, so it removes harness bookkeeping and can truncate large outputs. That consumer-specific tradeoff makes cross-harness memory practical while using substantially fewer tokens than native logs or replay-oriented formats.

ideas

• The consumer should determine the format. Full-fidelity replay needs metrics and structured payloads, while an agent forming memory needs the smallest record that still explains what happened.
• Normalization removes incidental variation. A shared record schema lets agents process experience from different harnesses without first interpreting each vendor’s envelopes, event streams, and duplicated fields.
• Compression is a practical constraint. Letta reports roughly fivefold token reductions on sampled coding sessions, with default truncation cutting both Claude Code and Codex logs further than the untruncated format.
• Portable experience enables portable learning. Listing and normalizing sessions across harnesses supports shared indexing, memory bootstrapping, search, and background consolidation.

quotes