feat: local delete with seen marking for reader-side removal

core/src/store.rs

@@ -571,6 +571,23 @@ impl Store {
             .is_some())
     }
 
+    /// Removes one message from the local store — the reader's delete, which
+    /// the server-side DELETE (sec 6.1) knows nothing about. The id is marked
+    /// seen (sec 10), so a copy still sitting on the server is fetched again
+    /// without being re-stored: deleting locally must not resurrect the
+    /// message on the next fetch.
+    pub fn delete_local(&self, folder: &str, id: &[u8; ID_LEN]) -> Result<(), Error> {
+        let table = match folder {
+            "sent" => "sent",
+            _ => "inbox",
+        };
+        self.db()
+            .execute(&format!("DELETE FROM {table} WHERE id = ?1"), params![id])?;
+        self.db()
+            .execute("INSERT OR IGNORE INTO seen (id, at) VALUES (?1, ?2)", params![id, now()])?;
+        Ok(())
+    }
+
     /// One folder, ordered by arrival or sending time. `folder` is "inbox",
     /// "requests", "sent" or "all".
     pub fn mail(&self, folder: &str) -> Result<Vec<Stored>, Error> {
@@ -887,6 +904,24 @@ mod tests {
         assert!(store.history("b@example.org").unwrap().is_empty());
     }
 
+    #[test]
+    fn local_delete_marks_seen_so_a_refetch_does_not_restore() {
+        let store = temp_store("delete-local");
+        let id = [3u8; 32];
+        store.store_inbox(&id, b"envelope", 100, false, true).unwrap();
+        store.delete_local("inbox", &id).unwrap();
+        assert!(store.mail("all").unwrap().is_empty());
+        // Sec 10: the id is seen, so the fetch pipeline will not re-store
+        // the still-kept server copy. (The dedupe is the pipeline's seen
+        // check, not store_inbox's — a direct insert is a caller override.)
+        assert!(store.seen(&id).unwrap());
+        // Sent copies delete locally too, with the same protection.
+        let sent_id = [4u8; 32];
+        store.store_sent(&sent_id, "bob@example.org", b"sent", 50).unwrap();
+        store.delete_local("sent", &sent_id).unwrap();
+        assert!(store.mail("sent").unwrap().is_empty());
+    }
+
     #[test]
     fn in_memory_store_round_trips() {
         let store = Store::open_in_memory().expect("memory store opens");