Run Oracle as HTTP Server

Instead of using the CLI, you can run the oracle as an HTTP server that accepts observation requests via API:

felidae oracle server \
  --homedir /persistent/keys \
  --node http://localhost:26657 \
  --bind 127.0.0.1:8081

The server exposes three endpoints:

• GET /pow-challenge?domain=<domain> - Request a Proof of Work (PoW) challenge for a domain. Returns JSON: {"challenge": "<hex>", "timestamp": <unix_secs>, "difficulty": <bits>}. The client must find a nonce such that SHA256(challenge + nonce) has at least difficulty leading zero bits, then submit that in the observe request.
• POST /observe - Submit an observation request. Requires a valid PoW token (see below). JSON body: {"domain": "example.com.", "pow_token": {"challenge": "<from /pow-challenge>", "nonce": <u64>, "timestamp": <from /pow-challenge>}}.
• GET /health - Health check endpoint.

Client-side PoW flow:

1. GET /pow-challenge?domain=example.com. to receive challenge, timestamp, difficulty.
2. Find a nonce (e.g. by incrementing from 0) such that the SHA256 hash of challenge + nonce has at least difficulty leading zero bits.
3. POST /observe with {"domain": "example.com.", "pow_token": {"challenge": "...", "nonce": <found>, "timestamp": <same>}}.

Tokens are valid for 5 minutes. PoW difficulty can be tuned with the POW_DIFFICULTY environment variable (default 19, minimum 8).

Example (after computing a valid nonce for the challenge):

curl -X POST http://localhost:8081/observe \
  -H "Content-Type: application/json" \
  -d '{"domain": "example.com.", "pow_token": {"challenge": "<from /pow-challenge>", "nonce": 12345, "timestamp": 1700000000}}'