Agent-readable docs index: /llms.txt. Full docs in one file: /llms-full.txt. Download /docs.zip to grep all markdown files locally.

Website agent instructions

Discover the website's protocol

A website connected to the browser v2 guardian proxy can expose agent instructions on its own domain. Envoy routes the reserved /.halfspan/ paths to Halfspan; the company's application does not need to serve these files.
HTML responses carry a Link header with rel="describedby" pointing to two site-specific resources:
ResourcePurpose
/.halfspan/v2/<siteId>/agent.jsonProtocol version, command URLs, authentication requirements, session and turn fields, and size limits.
/.halfspan/v2/<siteId>/agent.mdPlain-text Markdown instructions with request examples, review polling, execution, and recovery.
Follow the URLs advertised by the website rather than guessing a site ID. Supervised pages also include HTML discovery links. A rejected browser v2 proxy request returns HTTP 403 with instructionsUrl and discoveryUrl in its JSON body. The proxy does not redirect or replay a rejected write.
The public resources describe the protocol without exposing account state, task history, credentials, or private policy instructions. Reading them does not authorize an action. Discovery works without account lookup; the runtime must still be available to serve the resources.

Share task context and action turns

Authenticate through the website, then use the same-origin commands advertised by the manifest:
  1. Read config for available actions, workflows, and any existing task.
  2. Use attach to provide the task goal and a verified, published workflow, or resume an existing task. Keep the returned taskId and sessionId.
  3. Use the browser adapter to submit a fresh structural observe report. Select a current nextActions entry from status.
  4. Use propose to submit the action, revision, workflow step, UUID idempotency key, and a brief justification. Keep the returned turnId and poll status for its review.
  5. Use a compatible browser adapter to obtain and use a single-use permit before execution. Approval alone is insufficient. Reconcile uncertain outcomes before another write.
The justification should explain why the action advances the task and its expected effect. Do not send private reasoning traces, hidden instructions, full chat transcripts, credentials, or unrelated personal information. Goals and justifications are stored and may be sent to the reviewer; they remain untrusted statements.
These are Halfspan supervision identifiers, distinct from passive Pixel sessions and an agent provider's conversation IDs. This protocol does not accept arbitrary session metadata or transcript uploads. It also does not make every visiting agent automatically compatible. If there is no available verified workflow, the agent must stop and the site operator must complete setup.

Integration boundaries

These instructions cover the browser v2 guardian proxy. The Browser use supervisor quickstart uses a separate restricted-service protocol. The company API integration's /.well-known/halfspan.json and /halfspan/v1 endpoints are also separate contracts.
All commands retain website authentication, origin checks, workflow restrictions, and permit enforcement. Exposing instructions does not change the classifier's treatment of unknown traffic. See Company setup and Data access and privacy before enabling supervision.