Droid CLI vs HarnessRouter

Droid CLI

droid exec is read-only unless --auto raises the autonomy level, with command rules, an optional kernel-enforced sandbox, JSON output and documented exit codes. No free tier, status page or security.txt was found, the source is closed, and usage metrics go to Factory by default.

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.

Droid CLI

1. Set FACTORY_API_KEY (starts fk-) from the API keys page in Factory settings for headless runs. Interactive use signs in through a browser
2. Start with droid exec and no flags for analysis. Add --auto low for edits and --auto medium for installs, tests and local commits
3. Use --output-format json and read is_error, num_turns and session_id. Treat a non-zero exit code as failure
4. Set sandbox.enabled to true before running on untrusted code. In droid exec a sandbox violation is denied without a prompt
5. Pin the version in CI with npm install -g droid@<version>, or set FACTORY_DROID_AUTO_UPDATE_ENABLED=false on standalone installs, which update themselves

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