MemoServ: add SET NOTIFY and SET LIMIT

SET NOTIFY {ON|OFF} controls whether you're told about new memos on login;
SET LIMIT <n>|NONE sets your mailbox cap (honoured on SEND, NONE = the
network default). New memo_notify/memo_limit account fields + one
MemoPrefsSet event.

src/engine/db/account.rs

@@ -20,7 +20,7 @@ impl Db {
             verified,
             ajoin: Vec::new(),
             suspension: None,
-            memos: Vec::new(), memo_ignore: Vec::new(),
+            memos: Vec::new(), memo_ignore: Vec::new(), memo_notify: true, memo_limit: None,
             greet: String::new(),
             vhost: None,
             vhost_request: None,
@@ -59,7 +59,7 @@ impl Db {
             verified: true, // the external authority vouches for it
             ajoin: Vec::new(),
             suspension: None,
-            memos: Vec::new(), memo_ignore: Vec::new(),
+            memos: Vec::new(), memo_ignore: Vec::new(), memo_notify: true, memo_limit: None,
             greet: String::new(),
             vhost: None,
             vhost_request: None,

src/engine/db/channel.rs

@@ -688,6 +688,36 @@ impl Db {
         self.accounts.get(&key(account)).is_some_and(|a| a.memo_ignore.iter().any(|t| t.eq_ignore_ascii_case(sender)))
     }
 
+    /// Set whether `account` is notified about new memos on login.
+    pub fn set_memo_notify(&mut self, account: &str, on: bool) -> bool {
+        let k = key(account);
+        let Some(a) = self.accounts.get(&k) else { return false };
+        let limit = a.memo_limit;
+        let _ = self.log.append(Event::MemoPrefsSet { account: account.to_string(), notify: on, limit });
+        self.accounts.get_mut(&k).unwrap().memo_notify = on;
+        true
+    }
+
+    /// Set `account`'s mailbox cap (None = the network default).
+    pub fn set_memo_limit(&mut self, account: &str, limit: Option<u32>) -> bool {
+        let k = key(account);
+        let Some(a) = self.accounts.get(&k) else { return false };
+        let notify = a.memo_notify;
+        let _ = self.log.append(Event::MemoPrefsSet { account: account.to_string(), notify, limit });
+        self.accounts.get_mut(&k).unwrap().memo_limit = limit;
+        true
+    }
+
+    /// Whether `account` wants new-memo notifications (default on / unknown = on).
+    pub fn memo_notify_on(&self, account: &str) -> bool {
+        self.accounts.get(&key(account)).is_none_or(|a| a.memo_notify)
+    }
+
+    /// `account`'s configured mailbox cap, if any.
+    pub fn memo_limit_of(&self, account: &str) -> Option<u32> {
+        self.accounts.get(&key(account)).and_then(|a| a.memo_limit)
+    }
+
     /// How many unread memos an account has.
     pub fn unread_memos(&self, account: &str) -> usize {
         self.accounts.get(&key(account)).map_or(0, |a| a.memos.iter().filter(|m| !m.read).count())

src/engine/db/event.rs

@@ -31,6 +31,7 @@ pub enum Event {
     MemoDeleted { account: String, index: usize },
     MemoIgnoreAdd { account: String, target: String },
     MemoIgnoreDel { account: String, target: String },
+    MemoPrefsSet { account: String, notify: bool, limit: Option<u32> },
     NickGrouped { nick: String, account: String },
     NickUngrouped { nick: String },
     ChannelRegistered { name: String, founder: String, ts: u64 },
@@ -160,6 +161,7 @@ impl Event {
             | Event::MemoDeleted { .. }
             | Event::MemoIgnoreAdd { .. }
             | Event::MemoIgnoreDel { .. }
+            | Event::MemoPrefsSet { .. }
             | Event::NickGrouped { .. }
             | Event::NickUngrouped { .. }
             | Event::AccountSeen { .. }
@@ -354,6 +356,12 @@ pub(crate) fn apply(accounts: &mut HashMap<String, Account>, channels: &mut Hash
                 a.memo_ignore.retain(|t| !t.eq_ignore_ascii_case(&target));
             }
         }
+        Event::MemoPrefsSet { account, notify, limit } => {
+            if let Some(a) = accounts.get_mut(&key(&account)) {
+                a.memo_notify = notify;
+                a.memo_limit = limit;
+            }
+        }
         Event::NickGrouped { nick, account } => {
             grouped.insert(key(&nick), account);
         }

src/engine/db/mod.rs

@@ -82,6 +82,12 @@ pub struct Account {
     // Accounts this user won't receive memos from (MemoServ IGNORE).
     #[serde(default)]
     pub memo_ignore: Vec<String>,
+    // MemoServ SET NOTIFY: be told about new memos on login (default on).
+    #[serde(default = "verified_default")]
+    pub memo_notify: bool,
+    // MemoServ SET LIMIT: mailbox cap (None = the network default).
+    #[serde(default)]
+    pub memo_limit: Option<u32>,
     // Personal greet a bot shows when this account joins a greet-enabled channel.
     #[serde(default)]
     pub greet: String,

src/engine/db/store.rs

@@ -468,6 +468,18 @@ impl Store for Db {
     fn memo_is_ignored(&self, account: &str, sender: &str) -> bool {
         Db::memo_is_ignored(self, account, sender)
     }
+    fn set_memo_notify(&mut self, account: &str, on: bool) -> bool {
+        Db::set_memo_notify(self, account, on)
+    }
+    fn set_memo_limit(&mut self, account: &str, limit: Option<u32>) -> bool {
+        Db::set_memo_limit(self, account, limit)
+    }
+    fn memo_notify_on(&self, account: &str) -> bool {
+        Db::memo_notify_on(self, account)
+    }
+    fn memo_limit_of(&self, account: &str) -> Option<u32> {
+        Db::memo_limit_of(self, account)
+    }
     fn memo_check(&self, account: &str, sender: &str) -> Option<(bool, u64)> {
         Db::memo_check(self, account, sender)
     }

src/engine/db/tests.rs

@@ -32,7 +32,7 @@
         // which of the two competing registrations we're looking at.
         let alice = |tag: &str, ts: u64, home: &str| Account {
             name: "alice".into(), email: Some(tag.into()),
-            ts, home: home.into(), scram256: None, scram512: None, certfps: vec![], verified: true, ajoin: vec![], suspension: None, memos: vec![], memo_ignore: vec![], greet: String::new(), vhost: None, vhost_request: None, last_seen: ts, noexpire: false, expiry_warned: false, oper_note: None,
+            ts, home: home.into(), scram256: None, scram512: None, certfps: vec![], verified: true, ajoin: vec![], suspension: None, memos: vec![], memo_ignore: vec![], memo_notify: true, memo_limit: None, greet: String::new(), vhost: None, vhost_request: None, last_seen: ts, noexpire: false, expiry_warned: false, oper_note: None,
         };
         let converge = |first: &Account, second: &Account| {
             let (mut acc, mut ch, mut gr, mut bo, mut hc, mut nd) = (HashMap::new(), HashMap::new(), HashMap::new(), HashMap::new(), HostConfig::default(), NetData::default());
@@ -329,7 +329,7 @@
         db.register("alice", "pw", None).unwrap();
         let bob = Account {
             name: "bob".into(), email: None,
-            ts: 0, home: "peer".into(), scram256: None, scram512: None, certfps: vec![], verified: true, ajoin: vec![], suspension: None, memos: vec![], memo_ignore: vec![], greet: String::new(), vhost: None, vhost_request: None, last_seen: 0, noexpire: false, expiry_warned: false, oper_note: None,
+            ts: 0, home: "peer".into(), scram256: None, scram512: None, certfps: vec![], verified: true, ajoin: vec![], suspension: None, memos: vec![], memo_ignore: vec![], memo_notify: true, memo_limit: None, greet: String::new(), vhost: None, vhost_request: None, last_seen: 0, noexpire: false, expiry_warned: false, oper_note: None,
         };
         let entry = LogEntry { origin: "peer".into(), seq: 0, lamport: 1, event: Event::AccountRegistered(Box::new(bob)) };
         db.ingest(entry).unwrap();