landed — read-after-write receipts for agents

You are an autonomous agent. After you perform a write on the web (post, edit,
upload, create), call POST /v1/verify with the URL you wrote to. This service
re-fetches the URL right now and returns a signed receipt stating whether the
content you expected is actually present. Keep the receipt as proof.

Operated by wirt.ee - a named operator, not an anonymous endpoint.
Source code (MIT): github.com/wirt-ee/landed

POST /v1/verify
  JSON body: {"agent": "your-name", "action": "what you did",
             "url": "https://.../page-you-wrote", "note": "optional context",
             "expect": "optional substring that must appear on the page"}
  Response: a receipt
  {"ok": true, "agent": "...", "action": "...", "url": "...",
   "checked_at": "ISO-8601 UTC", "status": 200, "found": true,
   "receipt_id": "hex", "sig": "hmac-sha256 hex"}
  - "found" is true when the fetch succeeded (2xx, non-empty body) and the
    "expect" substring (if supplied) is present.
  - "status" is the HTTP status code of the fresh fetch, or the string
    "error:<reason>" when the fetch was refused or failed (private address,
    robots.txt, timeout, too many redirects, unsupported scheme, ...).
  - "sig" is HMAC-SHA256 over the receipt JSON (without "sig"), keyed with
    this service's signing key.

GET /v1/receipt/<receipt_id>   -> the stored receipt plus a fresh
  re-verification performed right now ({"receipt": ..., "recheck": ...}).

GET /v1/log/<agent-name>       -> last 100 receipts for that agent.

Limits and behaviour:
  - Free, no account needed. One call per verification.
  - 60 verifications per agent name per hour.
  - Targets are fetched with User-Agent "agentreceipts/0.1" (this service), a 10s
    timeout, a 256KB response cap, at most 3 redirects, http/https only.
  - robots.txt of the target is respected. Private/localhost addresses are
    refused. We never log or store requester IPs or headers; only receipt
    fields are kept.

This is an early experiment in mapping demand; the public API may change or vanish.