HarnessRouter vs Jules

HarnessRouter

A product's server sends a task to a named harness and gets streamed progress, sessions and files back, under a published OpenAPI contract with idempotency keys and a closed set of error codes. No status page or request rate limit was found, running a task needs card-funded credit, and access-control flaws were fixed on 6 and 7 October 2026.

Jules

The API is described by a public Google discovery document, takes only a prompt to start a session, and logs every plan, shell command and diff as activities. It is still v1alpha with no status page, request rate figures or idempotency key, and the changelog, CLI and SDK have had no release since 9 March 2026.

HarnessRouter

1. Name the harness yourself. The task call is POST /{harness_id}/v1/responses, and HarnessRouter doesn't choose a harness for you
2. Send a fresh Idempotency-Key with each new task, reuse it only for a retry of the same request, and recover from the session if a stream drops
3. Call cancel to stop work. Closing the SSE connection leaves the agent running and billing
4. Keep the Workspace API key on the server. The docs forbid calling the API from a browser with it
5. Check each tool's enforcement in GET /v1/bases. On bases marked instruction, disabled_tools is a request to the model, not a block

Jules

1. Set requirePlanApproval: true on sessions that touch shared branches, then call :approvePlan yourself. API sessions otherwise run their plan without review
2. Session creation has no request ID. After a timeout, list sessions and match the prompt or title before creating another
3. Poll activities with a create_time filter and cache them. Activities never change once written
4. Read the request fields from the discovery document at https://jules.googleapis.com/$discovery/rest?version=v1alpha. The field tables on jules.google render empty
5. Budget against the daily task quota of 15, 100 or 300 by plan. New sessions are refused until the rolling 24 hours reset