feat(protocol): apply v2 first-contact PoW on NewOrder and take actions

docs/MESSAGE_FLOW_AND_PROTOCOL.md

@@ -44,7 +44,7 @@ Used by `dm_helpers::ensure_order_dm_subscription`, startup `fetch_and_replay_st
 
 ### Proof-of-work (NIP-13)
 
-Required difficulty comes from kind **38385** tag `pow`. Mostrix uses `nostr_pow_from_instance` and `WrapOptions.pow` on the published event (GiftWrap outer on v1, signed kind-14 on v2). See **[POW_AND_OUTBOUND_EVENTS.md](POW_AND_OUTBOUND_EVENTS.md)**.
+Required difficulty comes from kind **38385** tags `pow` and optional `pow_first_contact`. Mostrix uses [`nostr_pow_for_protocol_dm`](../src/util/mostro_info.rs) in [`send_dm`](../src/util/dm_utils/mod.rs) (v2 first-contact actions: `max(pow, pow_first_contact)`). See **[POW_AND_OUTBOUND_EVENTS.md](POW_AND_OUTBOUND_EVENTS.md)**.
 
 ## Order Creation Flow
 

docs/POW_AND_OUTBOUND_EVENTS.md

@@ -8,14 +8,15 @@ This document describes how Mostrix applies **NIP-13 proof-of-work** to events i
   - **`pow`** — unsigned integer; parsed into [`MostroInstanceInfo.pow`](../src/util/mostro_info.rs) (`Option<u32>`).
   - **`protocol_version`** — `"1"` or `"2"`; drives [`transport_from_instance`](../src/util/mostro_info.rs) → [`AppState.transport`](../src/ui/app_state.rs). Missing tag → legacy GiftWrap.
 - There is **no** `pow` field in [`Settings`](../src/settings.rs) or in the generated `settings.toml` template.
-- **Effective bits** for signing: [`nostr_pow_from_instance`](../src/util/mostro_info.rs) maps `Option<&MostroInstanceInfo>` → `u8` by taking `info.pow`, clamping to `u8::MAX`, and using **0** when info is missing or `pow` is `None`.
+- Optional **`pow_first_contact`** on kind **38385** (when the daemon publishes it): parsed into [`MostroInstanceInfo.pow_first_contact`](../src/util/mostro_info.rs). When absent, effective first-contact toll = base `pow`.
+- **Effective bits** for signing: [`nostr_pow_from_instance`](../src/util/mostro_info.rs) maps base `pow`; [`nostr_pow_for_protocol_dm`](../src/util/mostro_info.rs) selects per-action bits for [`send_dm`](../src/util/dm_utils/mod.rs).
 
 ## Cached instance info at runtime
 
 - [`AppState.mostro_info`](../src/ui/app_state.rs) holds the latest fetched `MostroInstanceInfo`.
 - [`AppState.transport`](../src/ui/app_state.rs) mirrors resolved [`Transport`](../src/util/mod.rs). Updated via [`set_mostro_info`](../src/ui/app_state.rs).
 - [`EnterKeyContext`](../src/ui/key_handler/mod.rs) threads `mostro_info` into async work without re-fetching per message.
-- [`send_dm`](../src/util/dm_utils/mod.rs) takes `mostro_instance: Option<&MostroInstanceInfo>` and computes `pow = nostr_pow_from_instance(mostro_instance)` once per send.
+- [`send_dm`](../src/util/dm_utils/mod.rs) takes `mostro_instance: Option<&MostroInstanceInfo>` and computes `pow = nostr_pow_for_protocol_dm(mostro_instance, action)` once per send.
 
 At startup (and on reload/reconnect via [`dm_transport_for_mostro`](../src/ui/key_handler/async_tasks.rs)), instance info is fetched **before** the DM listener spawns when relays are reachable.
 
@@ -27,7 +28,7 @@ At startup (and on reload/reconnect via [`dm_transport_for_mostro`](../src/ui/ke
 - **v2 (`Nip44Direct`)**: PoW on the **signed kind-14** event (`WrapOptions.pow`).
 - **NIP-40 expiration**: default **now + 30 days** on v2 when the caller passes `expiration: None` (`default_dm_expiration`).
 
-First-contact actions on strict v2 nodes may need higher PoW than instance `pow` (`pow_first_contact` on the daemon — not advertised in 38385 today).
+First-contact actions on strict v2 nodes may need higher PoW than instance `pow` (`pow_first_contact` on the daemon). Mostrix applies `max(pow, pow_first_contact)` on v2 for `NewOrder`, `TakeBuy`, and `TakeSell` via [`nostr_pow_for_protocol_dm`](../src/util/mostro_info.rs). When the kind-38385 `pow_first_contact` tag is absent, the effective toll defaults to base `pow` (same as the daemon).
 
 ## Chat vs protocol PoW
 

src/ui/tabs/mostro_info_tab.rs

@@ -123,6 +123,13 @@ fn build_info_lines(info: &MostroInstanceInfo) -> Vec<Line<'static>> {
     );
     push_opt_f64(&mut lines, "Fee (fraction)", info.fee);
     push_opt_u32(&mut lines, "Required PoW", info.pow);
+    if info.pow_first_contact.is_some() {
+        push_opt_u32(
+            &mut lines,
+            "Required PoW (first contact, v2)",
+            info.pow_first_contact,
+        );
+    }
     push_kv(
         &mut lines,
         "Anti-abuse bonds",

src/util/dm_utils/mod.rs

@@ -32,7 +32,7 @@ use crate::ui::{MessageNotification, OrderMessage};
 use crate::util::db_utils::{delete_order_by_id, save_order, update_order_status};
 use crate::util::filters::filter_protocol_dm_from_mostro;
 use crate::util::mostro_info::{
-    nostr_pow_from_instance, transport_from_instance, MostroInstanceInfo,
+    nostr_pow_for_protocol_dm, transport_from_instance, MostroInstanceInfo,
 };
 use crate::util::order_utils::{
     inferred_status_from_trade_action, map_action_to_status, should_apply_status_transition,
@@ -222,9 +222,9 @@ pub async fn send_dm(
     expiration: Option<Timestamp>,
     mostro_instance: Option<&MostroInstanceInfo>,
 ) -> Result<()> {
-    let pow = nostr_pow_from_instance(mostro_instance);
     let message = Message::from_json(&payload)
         .map_err(|e| anyhow::anyhow!("Failed to deserialize message: {e}"))?;
+    let pow = nostr_pow_for_protocol_dm(mostro_instance, &message.get_inner_message_kind().action);
     let identity_keys = identity_keys.unwrap_or(trade_keys);
     let transport = transport_from_instance(mostro_instance);
     let expiration = match (transport, expiration) {

src/util/mostro_info.rs

@@ -1,7 +1,7 @@
 use crate::settings::load_settings_from_disk;
 use crate::util::dm_utils::FETCH_EVENTS_TIMEOUT;
 use anyhow::{anyhow, Result};
-use mostro_core::prelude::Transport;
+use mostro_core::prelude::{Action, Transport};
 use nostr_sdk::prelude::*;
 use std::str::FromStr;
 
@@ -45,6 +45,9 @@ pub struct MostroInstanceInfo {
     pub max_orders_per_response: Option<u32>,
     pub fee: Option<f64>,
     pub pow: Option<u32>,
+    /// First-contact PoW toll on v2 (kind 38385 tag `pow_first_contact`). When absent, daemon
+    /// defaults to [`Self::pow`]; Mostrix mirrors that in [`effective_pow_first_contact_from_instance`].
+    pub pow_first_contact: Option<u32>,
     /// Wire transport version from kind-38385 tag `protocol_version` (`"1"` / `"2"`).
     pub protocol_version: Option<u8>,
     /// Anti-abuse bond feature flag from kind-38385 tag `bond_enabled` (`"true"` / `"false"`).
@@ -101,13 +104,48 @@ impl MostroInstanceInfo {
     }
 }
 
+fn clamp_pow_bits(bits: Option<u32>) -> u8 {
+    bits.map(|n| (n.min(u8::MAX as u32)) as u8).unwrap_or(0)
+}
+
 /// NIP-13 difficulty bits for outbound events from cached Mostro instance info (kind 38385 tag `pow`).
 /// Returns `0` when info is missing or the tag is absent. Values above `u8::MAX` clamp to 255.
 pub fn nostr_pow_from_instance(instance: Option<&MostroInstanceInfo>) -> u8 {
-    instance
-        .and_then(|i| i.pow)
-        .map(|n| (n.min(u8::MAX as u32)) as u8)
-        .unwrap_or(0)
+    clamp_pow_bits(instance.and_then(|i| i.pow))
+}
+
+/// Effective first-contact PoW bits (mirrors Mostro daemon `effective_pow_first_contact`).
+///
+/// Uses tag `pow_first_contact` when present; otherwise falls back to base `pow`.
+pub fn effective_pow_first_contact_from_instance(instance: Option<&MostroInstanceInfo>) -> u8 {
+    match instance {
+        Some(i) => clamp_pow_bits(i.pow_first_contact.or(i.pow)),
+        None => 0,
+    }
+}
+
+/// Protocol actions that introduce a new trade key to Mostro (v2 spam gate first-contact lane).
+pub fn is_v2_first_contact_protocol_action(action: &Action) -> bool {
+    matches!(
+        action,
+        Action::NewOrder | Action::TakeBuy | Action::TakeSell
+    )
+}
+
+/// NIP-13 bits for a protocol DM toward Mostro.
+///
+/// v1 GiftWrap: always base instance `pow` (daemon spam gate is v2-only).
+/// v2 NIP-44: first-contact actions use `max(pow, pow_first_contact)` so new order/take
+/// clears the daemon's stiffer toll when operators set `pow_first_contact` above `pow`.
+pub fn nostr_pow_for_protocol_dm(instance: Option<&MostroInstanceInfo>, action: &Action) -> u8 {
+    let base = nostr_pow_from_instance(instance);
+    if transport_from_instance(instance) == Transport::Nip44Direct
+        && is_v2_first_contact_protocol_action(action)
+    {
+        base.max(effective_pow_first_contact_from_instance(instance))
+    } else {
+        base
+    }
 }
 
 /// Whether the connected Mostro instance has anti-abuse bonds enabled (kind 38385 `bond_enabled`).
@@ -183,6 +221,9 @@ pub fn mostro_info_from_tags(tags: Tags) -> Result<MostroInstanceInfo> {
             "pow" => {
                 info.pow = MostroInstanceInfo::parse_u32(value);
             }
+            "pow_first_contact" => {
+                info.pow_first_contact = MostroInstanceInfo::parse_u32(value);
+            }
             "protocol_version" => {
                 info.protocol_version = MostroInstanceInfo::parse_u8(value);
             }
@@ -464,6 +505,66 @@ mod tests {
         );
     }
 
+    #[test]
+    fn parse_pow_first_contact_from_tags() {
+        let mut tags = Tags::new();
+        tags.push(Tag::parse(["pow", "8"]).unwrap());
+        tags.push(Tag::parse(["pow_first_contact", "16"]).unwrap());
+        let result = mostro_info_from_tags(tags).unwrap();
+        assert_eq!(result.pow, Some(8));
+        assert_eq!(result.pow_first_contact, Some(16));
+    }
+
+    #[test]
+    fn effective_pow_first_contact_falls_back_to_base_pow() {
+        assert_eq!(effective_pow_first_contact_from_instance(None), 0);
+        assert_eq!(
+            effective_pow_first_contact_from_instance(Some(&MostroInstanceInfo {
+                pow: Some(8),
+                ..Default::default()
+            })),
+            8
+        );
+        assert_eq!(
+            effective_pow_first_contact_from_instance(Some(&MostroInstanceInfo {
+                pow: Some(8),
+                pow_first_contact: Some(16),
+                ..Default::default()
+            })),
+            16
+        );
+    }
+
+    #[test]
+    fn nostr_pow_for_protocol_dm_v2_first_contact_uses_max_toll() {
+        let info = MostroInstanceInfo {
+            pow: Some(8),
+            pow_first_contact: Some(16),
+            protocol_version: Some(2),
+            ..Default::default()
+        };
+        assert_eq!(
+            nostr_pow_for_protocol_dm(Some(&info), &Action::NewOrder),
+            16
+        );
+        assert_eq!(nostr_pow_for_protocol_dm(Some(&info), &Action::TakeBuy), 16);
+        assert_eq!(
+            nostr_pow_for_protocol_dm(Some(&info), &Action::AddInvoice),
+            8
+        );
+    }
+
+    #[test]
+    fn nostr_pow_for_protocol_dm_v1_ignores_first_contact_toll() {
+        let info = MostroInstanceInfo {
+            pow: Some(8),
+            pow_first_contact: Some(16),
+            protocol_version: Some(1),
+            ..Default::default()
+        };
+        assert_eq!(nostr_pow_for_protocol_dm(Some(&info), &Action::NewOrder), 8);
+    }
+
     // Fetch tests would require a mock or test double for nostr_sdk::Client
     // (e.g. a trait + impl for production and a mock that returns empty events
     // or simulates timeout). Not implemented here to avoid refactoring the public API.