NickServ: add SET KILL to toggle nick protection

Nick protection was unconditional. SET KILL OFF lets an account opt out —
an unidentified user keeping one of its nicks is no longer prompted or
renamed to a guest. Stored inverted (no_protect) so protection stays the
default. Accepts Anope's ON/QUICK/IMMED/OFF; grace is a fixed interval
here, so the finer variants simply enable protection like ON.

src/engine/db/account.rs

@@ -21,7 +21,7 @@ impl Db {
             ajoin: Vec::new(),
             suspension: None,
             memos: Vec::new(), memo_ignore: Vec::new(), memo_notify: true, memo_limit: None,
-            greet: String::new(), no_autoop: false,
+            greet: String::new(), no_autoop: false, no_protect: false,
             vhost: None,
             vhost_request: None,
             last_seen: now(),
@@ -60,7 +60,7 @@ impl Db {
             ajoin: Vec::new(),
             suspension: None,
             memos: Vec::new(), memo_ignore: Vec::new(), memo_notify: true, memo_limit: None,
-            greet: String::new(), no_autoop: false,
+            greet: String::new(), no_autoop: false, no_protect: false,
             vhost: None,
             vhost_request: None,
             last_seen: now(),
@@ -434,6 +434,22 @@ impl Db {
         self.accounts.get(&key(account)).is_none_or(|a| !a.no_autoop)
     }
 
+    /// Set whether `account`'s nicks are protected by the enforcer (SET KILL).
+    pub fn set_account_kill(&mut self, account: &str, on: bool) -> Result<(), RegError> {
+        let k = key(account);
+        if !self.accounts.contains_key(&k) {
+            return Err(RegError::Internal);
+        }
+        self.log.append(Event::AccountKillSet { account: account.to_string(), on }).map_err(|_| RegError::Internal)?;
+        self.accounts.get_mut(&k).unwrap().no_protect = !on;
+        Ok(())
+    }
+
+    /// Whether `account`'s nicks are protected by the enforcer (default true).
+    pub fn account_wants_protect(&self, account: &str) -> bool {
+        self.accounts.get(&key(account)).is_none_or(|a| !a.no_protect)
+    }
+
     /// Replace `account`'s password with freshly derived credentials.
     pub fn set_credentials(&mut self, account: &str, creds: Credentials) -> Result<(), RegError> {
         let k = key(account);

src/engine/db/event.rs

@@ -16,6 +16,7 @@ pub enum Event {
     AccountEmailSet { account: String, email: Option<String> },
     AccountGreetSet { account: String, greet: String },
     AccountAutoOpSet { account: String, on: bool },
+    AccountKillSet { account: String, on: bool },
     AccountPasswordSet { account: String, scram256: String, scram512: String },
     AccountDropped { account: String },
     AccountVerified { account: String },
@@ -149,6 +150,7 @@ impl Event {
             | Event::AccountEmailSet { .. }
             | Event::AccountGreetSet { .. }
             | Event::AccountAutoOpSet { .. }
+            | Event::AccountKillSet { .. }
             | Event::AccountPasswordSet { .. }
             | Event::AccountDropped { .. }
             | Event::AccountVerified { .. }
@@ -280,6 +282,11 @@ pub(crate) fn apply(accounts: &mut HashMap<String, Account>, channels: &mut Hash
                 a.no_autoop = !on;
             }
         }
+        Event::AccountKillSet { account, on } => {
+            if let Some(a) = accounts.get_mut(&key(&account)) {
+                a.no_protect = !on;
+            }
+        }
         Event::AccountPasswordSet { account, scram256, scram512 } => {
             if let Some(a) = accounts.get_mut(&key(&account)) {
                 a.scram256 = Some(scram256);

src/engine/db/mod.rs

@@ -96,6 +96,11 @@ pub struct Account {
     // (auto-op enabled) is the zero value.
     #[serde(default)]
     pub no_autoop: bool,
+    // NickServ SET KILL: when off, this account's nicks are not protected — an
+    // unidentified user keeping the nick is never renamed to a guest. Stored
+    // inverted so the default (protection enabled) is the zero value.
+    #[serde(default)]
+    pub no_protect: bool,
     // Assigned vhost (HostServ), applied to the displayed host on identify.
     #[serde(default)]
     pub vhost: Option<Vhost>,

src/engine/db/store.rs

@@ -88,6 +88,12 @@ impl Store for Db {
     fn account_wants_autoop(&self, account: &str) -> bool {
         Db::account_wants_autoop(self, account)
     }
+    fn set_account_kill(&mut self, account: &str, on: bool) -> Result<(), RegError> {
+        Db::set_account_kill(self, account, on)
+    }
+    fn account_wants_protect(&self, account: &str) -> bool {
+        Db::account_wants_protect(self, account)
+    }
     fn set_vhost(&mut self, account: &str, host: &str, setter: &str, ttl: Option<u64>) -> Result<(), RegError> {
         Db::set_vhost(self, account, host, setter, ttl)
     }

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![], memo_notify: true, memo_limit: None, greet: String::new(), no_autoop: false, 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(), no_autoop: false, no_protect: false, 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![], memo_notify: true, memo_limit: None, greet: String::new(), no_autoop: false, 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(), no_autoop: false, no_protect: false, 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();