Add delete email with optimistic UI update

Press 'd' to delete the selected email. Removes it from the list
immediately and performs the server-side delete in the background
for a snappy user experience.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/inbox.rs

@@ -170,6 +170,29 @@ pub(crate) fn fetch_body(
     extract_plain_text(&raw)
 }
 
+/// Delete an email by sequence number (flag as \Deleted + expunge).
+pub(crate) fn delete_email(
+    session: &mut Option<ImapSession>,
+    seq: u32,
+    config: &Config,
+) -> Result<(), String> {
+    let s = ensure_session(session, config)?;
+    let range = seq.to_string();
+    match s {
+        ImapSession::Plain(s) => {
+            s.select("INBOX").map_err(|e| e.to_string())?;
+            s.store(&range, "+FLAGS (\\Deleted)").map_err(|e| e.to_string())?;
+            s.expunge().map_err(|e| e.to_string())?;
+        }
+        ImapSession::Tls(s) => {
+            s.select("INBOX").map_err(|e| e.to_string())?;
+            s.store(&range, "+FLAGS (\\Deleted)").map_err(|e| e.to_string())?;
+            s.expunge().map_err(|e| e.to_string())?;
+        }
+    }
+    Ok(())
+}
+
 fn extract_raw_body(fetches: &[imap::types::Fetch]) -> Option<Vec<u8>> {
     fetches.first().and_then(|f| {
         f.body().map(|b| b.to_vec())

src/lib.rs

@@ -34,6 +34,7 @@ enum WorkerCmd {
     Refresh,
     FetchMore { oldest_seq: u32 },
     FetchBody { seq: u32 },
+    Delete { seq: u32 },
     Quit,
 }
 
@@ -41,6 +42,7 @@ enum WorkerResult {
     Refreshed(Result<inbox::Inbox, String>),
     FetchedMore(Result<(Vec<Email>, u32), String>),
     Body { seq: u32, result: Result<String, String> },
+    Deleted(Result<(), String>),
 }
 
 fn worker_loop(
@@ -64,6 +66,10 @@ fn worker_loop(
                 let result = inbox::fetch_body(&mut session, seq, &config);
                 let _ = result_tx.send(WorkerResult::Body { seq, result });
             }
+            WorkerCmd::Delete { seq } => {
+                let result = inbox::delete_email(&mut session, seq, &config);
+                let _ = result_tx.send(WorkerResult::Deleted(result));
+            }
             WorkerCmd::Quit => break,
         }
     }
@@ -155,6 +161,11 @@ pub fn main(config: &Config, terminal: &mut Terminal<CrosstermBackend<Stdout>>)
                         }
                     }
                 }
+                WorkerResult::Deleted(result) => {
+                    if let Err(e) = result {
+                        error = Some(format!("Delete failed: {}", e));
+                    }
+                }
             }
         }
 
@@ -248,7 +259,7 @@ pub fn main(config: &Config, terminal: &mut Terminal<CrosstermBackend<Stdout>>)
                 .scroll((preview_scroll, 0));
             frame.render_widget(preview, layout[1]);
 
-            let status = Paragraph::new(" 'q' quit | 'r' refresh | ↑/↓ navigate | Tab switch pane")
+            let status = Paragraph::new(" 'q' quit | 'r' refresh | 'd' delete | ↑/↓ navigate | Tab switch pane")
                 .style(Style::default().fg(Color::DarkGray));
             frame.render_widget(status, layout[2]);
         })?;
@@ -317,6 +328,33 @@ pub fn main(config: &Config, terminal: &mut Terminal<CrosstermBackend<Stdout>>)
                             preview_scroll = preview_scroll.saturating_sub(1);
                         }
                     }
+                    KeyCode::Char('d') if focus == Focus::Inbox => {
+                        if let Some(idx) = list_state.selected() {
+                            if idx < emails.len() {
+                                let seq = emails[idx].seq;
+                                // Remove from UI immediately
+                                emails.remove(idx);
+                                if emails.is_empty() {
+                                    list_state.select(None);
+                                    preview_seq = None;
+                                    preview_body.clear();
+                                } else {
+                                    let new_idx = idx.min(emails.len().saturating_sub(1));
+                                    list_state.select(Some(new_idx));
+                                    let new_seq = emails[new_idx].seq;
+                                    if preview_seq != Some(new_seq) {
+                                        preview_seq = Some(new_seq);
+                                        preview_body.clear();
+                                        preview_scroll = 0;
+                                        body_loading = true;
+                                        let _ = cmd_tx.send(WorkerCmd::FetchBody { seq: new_seq });
+                                    }
+                                }
+                                // Delete on server in background
+                                let _ = cmd_tx.send(WorkerCmd::Delete { seq });
+                            }
+                        }
+                    }
                     _ => {}
                 }
             }