Fix IMAP UID SEARCH crash and RFC 3501 flag parentheses

Agent-Logs-Url: https://github.com/christianlouis/InboxConverge/sessions/a44d5455-25ea-49b9-8310-4efd6d467e84

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>

CHANGELOG.md

@@ -7,6 +7,22 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 <!-- version list -->
 
+## [Unreleased]
+
+### Fixed
+
+- **IMAP: fix T-Online BYE "Too many invalid IMAP commands"** — `UID STORE` flag
+  arguments now use RFC 3501–required parentheses: `+FLAGS (\Seen)` and
+  `+FLAGS (\Deleted)`.  Strict servers such as T-Online reject the bare
+  `+FLAGS \Seen` syntax as a `BAD` command and forcefully drop the connection.
+- **IMAP: fix `aioimaplib` crash on `UID SEARCH`** — `aioimaplib`'s `.uid()`
+  wrapper explicitly blocks `"search"`, raising
+  `command UID only possible with COPY, FETCH, EXPUNGE (w/UIDPLUS) or STORE`.
+  The initial UNSEEN discovery now uses a plain `SEARCH UNSEEN` to obtain
+  sequence numbers, followed by a lightweight `FETCH (UID)` to resolve them
+  to stable UIDs; all subsequent operations (`FETCH`, `STORE`) continue to
+  use the UID form.
+
 ## v0.4.2 (2026-03-28)
 
 ### Bug Fixes