fix: 4 small surgical bugs

Salvages #23302 by @Bartok9. Four independent one-area fixes:

1. kanban boards delete alias now hard-deletes (not archives) — the
   alias didn't carry --delete, so getattr(args, 'delete', False)
   returned False. Detect boards_action=='delete' explicitly.
2. Gateway auto-title failures no longer leak as user-visible
   warnings — debug-log only since they're not actionable.
3. Background process completion notification snaps truncation to
   the next newline boundary, prepends a marker when content is
   dropped.
4. _cprint() schedules the run_in_terminal coroutine via
   asyncio.ensure_future so output isn't silently dropped from
   background threads (fixes #23185 Bug A). Skips the
   double-print fallback that would fire for mock paths.

gateway/run.py

@@ -13956,7 +13956,19 @@ class GatewayRunner:
                 from tools.process_registry import process_registry as _pr_check
                 if agent_notify and not _pr_check.is_completion_consumed(session_id):
                     from tools.ansi_strip import strip_ansi
-                    _out = strip_ansi(session.output_buffer[-2000:]) if session.output_buffer else ""
+                    _raw = strip_ansi(session.output_buffer) if session.output_buffer else ""
+                    # Truncate at line boundaries so notifications never start
+                    # mid-line (fixes #23284). Keep the last ~2000 chars but
+                    # snap to the nearest preceding newline, then prepend a
+                    # truncation marker when output was cut.
+                    _LIMIT = 2000
+                    if len(_raw) > _LIMIT:
+                        _tail = _raw[-_LIMIT:]
+                        _nl = _tail.find("\n")
+                        _tail = _tail[_nl + 1:] if _nl != -1 else _tail
+                        _out = f"[… output truncated — showing last {len(_tail)} chars]\n{_tail}"
+                    else:
+                        _out = _raw
                     synth_text = (
                         f"[IMPORTANT: Background process {session_id} completed "
                         f"(exit code {session.exit_code}).\n"
@@ -16156,13 +16168,16 @@ class GatewayRunner:
                 try:
                     from agent.title_generator import maybe_auto_title
                     all_msgs = result_holder[0].get("messages", []) if result_holder[0] else []
-                    # Route title-generation failures through the agent's
-                    # user-visible warning channel so a depleted auxiliary
-                    # provider doesn't silently leave sessions untitled
-                    # (issue #15775).
-                    _title_failure_cb = getattr(
-                        agent, "_emit_auxiliary_failure", None
-                    )
+                    # In Gateway mode, auto-title failures must NOT be
+                    # surfaced as user-visible messages (fixes #23246).
+                    # Log them at debug level only — they are not actionable
+                    # to the end user. CLI mode keeps the existing behaviour
+                    # via the agent's _emit_auxiliary_failure path.
+                    def _title_failure_cb(task: str, exc: BaseException) -> None:
+                        logger.debug(
+                            "Gateway auto-title failure suppressed (not user-visible): %s: %s",
+                            task, exc,
+                        )
                     maybe_auto_title_kwargs = {
                         "failure_callback": _title_failure_cb,
                         "main_runtime": {