Fix exchange rates other event

Author: grunch

src/other_events.md

@@ -224,15 +224,9 @@ The operator of a Mostro instance decides which relays the events from that inst
 
 The `r` label indicates the relays through which the Mostro instance is publishing its events.
 
-## Exchange Rates (NIP-33 Kind 30078)
+## Exchange Rates
 
-Each Mostro instance can optionally publish Bitcoin/fiat exchange rates to Nostr relays as [NIP-33](https://github.com/nostr-protocol/nips/blob/master/33.md) addressable events (kind 30078). This enables:
-
-- **Censorship resistance**: Mobile clients in censored regions (Venezuela, Cuba, etc.) can fetch rates via Nostr relays
-- **Zero scaling cost**: Relays distribute events; no per-request infrastructure needed for the rate provider
-- **Backward compatibility**: HTTP API remains available as fallback for clients
-
-The daemon fetches rates from a price API (e.g., Yadio) at a configurable interval and publishes the complete payload to Nostr. This is a **replaceable event** (NIP-33), meaning relays keep only the latest version identified by the `d` tag.
+Each Mostro instance publish Bitcoin/fiat exchange rates to Nostr relays as addressable events (kind 30078):
 
 ### Event Structure
 
@@ -259,10 +253,10 @@ The daemon fetches rates from a price API (e.g., Yadio) at a configurable interv
 
 ### Tags
 
-- **d**: `"mostro-rates"` — NIP-33 identifier that makes this event replaceable. Each new rate update replaces the previous one.
+- **d**: `"mostro-rates"` — NIP-01 identifier that makes this event replaceable. Each new rate update replaces the previous one.
 - **published_at**: Unix timestamp when the daemon published the event (daemon time, not source timestamp).
 - **source**: Rate source identifier (e.g., `"yadio"`).
-- **expiration**: Unix timestamp for event expiration ([NIP-40](https://github.com/nostr-protocol/nips/blob/master/40.md)). Prevents stale rates from being served. Calculated as `min(update_interval × 2, 3600)` to allow for delays while capping at 1 hour.
+- **expiration**: Unix timestamp for event expiration ([NIP-40](https://github.com/nostr-protocol/nips/blob/master/40.md)). Prevents stale rates from being served.
 
 ### Content Format
 
@@ -284,51 +278,6 @@ The `content` field contains the full rate response in JSON format matching the
 
 **Rate semantics**: Each value under `"BTC"` represents the price of 1 BTC in that currency.
 
-**Example**: `"USD": 50000.0` means 1 BTC = 50,000 USD.
-
-### Configuration
-
-Exchange rate publishing is configured in `settings.toml`:
-
-```toml
-[mostro]
-# Enable Nostr exchange rate publishing (default: true)
-publish_exchange_rates_to_nostr = true
-
-# Update interval in seconds (default: 300, minimum: 60)
-exchange_rates_update_interval_seconds = 300
-```
-
-If `publish_exchange_rates_to_nostr` is `false`, no exchange rate events are published.
-
-### Client Usage
-
-Clients should:
-
-1. **Subscribe** to events with filter: `{"kinds": [30078], "#d": ["mostro-rates"], "authors": [<mostro_pubkey>]}`
-2. **Verify** the event signature and that `event.pubkey` matches the expected Mostro instance pubkey (prevents price manipulation)
-3. **Parse** the `content` field as JSON
-4. **Check** the `expiration` tag to ensure rates are not stale
-5. **Fall back** to HTTP API if Nostr fails or rates are expired
-
-### Security Considerations
-
-**⚠️ CRITICAL**: Clients MUST verify `event.pubkey == expected_mostro_pubkey` before using the rates. Without this check, a malicious actor could publish fake rates to manipulate prices.
-
-**Signature verification**: Use standard Nostr signature verification (NIP-01) to ensure the event was signed by the Mostro instance's private key.
-
-**Expiration**: Clients should reject events where `current_time > expiration` to avoid using stale rates.
-
-### Why Nostr?
-
-In countries with government censorship (Venezuela, Cuba, Iran, etc.), HTTP access to exchange rate APIs is often blocked. Nostr's decentralized relay network makes censorship impractical:
-
-- **Geographic distribution**: Relays are hosted worldwide
-- **No single point of failure**: Blocking one relay doesn't affect others
-- **Standard Nostr infrastructure**: No special infrastructure needed; uses existing Nostr relay network
-
-This aligns with Mostro's mission to provide censorship-resistant peer-to-peer Bitcoin trading.
-
 # Development Fee
 
 The development fee mechanism provides sustainable funding for Mostro development by automatically sending a configurable percentage of the Mostro fee to a lightning address on each successful order, this a regular event with kind 8383 which is expected to be stored by relays.