Artifacts

An artifact is a session-bound file. Agents publish artifacts as the durable, reviewable output of their work — Markdown reports, JSON results, CSVs, images.

Publish an artifact

await session.artifact('report.md', markdown, { contentType: 'text/markdown' });

The content can be a string or an in-memory buffer:

await session.artifact('summary.json', JSON.stringify({ ok: true }), {
  contentType: 'application/json',
});

Agents that generate a file in the sandbox first can read it back and publish the bytes:

const bytes = await session.fs.readBytes('/workspace/report.md');
await session.artifact('report.md', bytes, { contentType: 'text/markdown' });

Read from the CLI

fh artifacts <session-id>
fh artifact get <session-id> report.md --out ./reports/report.md

What gets persisted

The session store records artifact metadata (id, name, content type, byte size, created time) alongside the session entry that produced it. The bytes are stored separately:

• File store (default): files under .fabricharness/sessions/<id>/artifacts/.
• SQLite store: BLOB column.
• Postgres store: BYTEA column or external blob URL.
• Cloud stores (designed): Azure Blob / ADLS, S3, R2.

Patterns

• Reports. A triage agent publishes triage-report.md for reviewers.
• Generated code. A migration agent publishes the proposed diff as an artifact and asks for approval before applying it.
• Datasets. A data agent publishes profiled CSVs alongside the prompt that produced them.

See also: fh artifacts, fh artifact get.