Understand Hermes Trajectory JSONL

Read, validate, and handle Hermes ShareGPT-compatible trajectory files for debugging, evaluation, and training-data workflows. This guide focuses on the public implementation contract; the official Hermes documentation remains the source of truth as interfaces evolve.

How the interface works

Hermes can save completed conversations to trajectory_samples.jsonl and failed or interrupted work to failed_trajectories.jsonl. Batch runs use custom output files with additional metadata.

Each JSONL line is a self-contained object. Conversation roles are normalized to ShareGPT names, reasoning is represented in think blocks, and tool calls and responses use consistent XML-wrapped JSON.

Batch entries add prompt indexes, metadata, completion state, API-call counts, toolsets, normalized tool statistics, and error counts. Consistent zero-filled tool keys help dataset loaders avoid schema drift.

Trajectory files may contain prompts, tool arguments, outputs, and reasoning. Treat them as potentially sensitive operational data; redact or exclude private material before sharing or publishing.

Practical checklist

Enable trajectory saving only for a defined debugging or data purpose.
Keep completed and failed samples distinguishable.
Validate every nonblank line as JSON before loading a dataset.
Filter on completion and partial state according to the evaluation contract.
Run a privacy review before moving files outside the local project boundary.

Common pitfalls

Committing raw trajectories that contain secrets, private paths, or customer data.
Parsing JSONL as one giant JSON document.
Mixing completed and failed runs without checking status fields.
Assuming normalized formatting means the underlying content is safe or high quality.

Verification steps

Load every line independently and assert required top-level fields.
Check conversation roles and tool-response pairing.
Compare declared tool statistics with sampled conversation events.
Open a small dataset slice in the target loader and confirm stable columns before a large import.

Official reference

https://hermes-agent.nousresearch.com/docs/developer-guide/trajectory-format