Phase 7: Directory restructuring (messaging/ and tests/)

- Create messaging/platforms/ (base, discord, telegram, factory)
- Create messaging/rendering/ (discord_markdown, telegram_markdown)
- Create messaging/trees/ (data, repository, processor, queue_manager)
- Organize tests/ into api/, providers/, messaging/, cli/, config/
- Add backward-compatible re-exports at old locations
- Update handler.py and test_messaging_factory.py imports
- Fix Telegram type hints for TELEGRAM_AVAILABLE=False case
- Fix Python 3 except syntax in discord_markdown

Co-authored-by: Ali Khokhar <alishahryar2@gmail.com>

tests/cli/test_process_registry.py

@@ -0,0 +1,78 @@
+import os
+from unittest.mock import patch
+
+
+def test_process_registry_register_pid_zero_noop():
+    """register_pid(0) is a no-op (early return)."""
+    from cli import process_registry as pr
+
+    before = len(pr._pids)
+    pr.register_pid(0)
+    assert len(pr._pids) == before
+
+
+def test_process_registry_unregister_pid_zero_noop():
+    """unregister_pid(0) is a no-op."""
+    from cli import process_registry as pr
+
+    pr.register_pid(99999)
+    pr.unregister_pid(0)
+    assert 99999 in pr._pids
+    pr.unregister_pid(99999)
+
+
+def test_process_registry_ensure_atexit_idempotent():
+    """Second call to ensure_atexit_registered is idempotent."""
+    from cli import process_registry as pr
+
+    pr.ensure_atexit_registered()
+    pr.ensure_atexit_registered()
+    # Should not raise; atexit handler registered once
+
+
+def test_process_registry_kill_all_exception_logged_no_raise(monkeypatch):
+    """Exception in os.kill/taskkill is logged but does not raise."""
+    from cli import process_registry as pr
+
+    monkeypatch.setattr(pr, "_pids", {99999})
+    monkeypatch.setattr(os, "name", "posix", raising=False)
+
+    def _kill_raises(pid, sig):
+        raise ProcessLookupError("no such process")
+
+    with patch("os.kill", _kill_raises):
+        pr.kill_all_best_effort()
+    # Should not raise
+
+
+def test_process_registry_register_unregister_does_not_crash():
+    from cli import process_registry as pr
+
+    pr.register_pid(12345)
+    pr.unregister_pid(12345)
+
+
+def test_process_registry_kill_all_best_effort_empty_is_noop():
+    from cli import process_registry as pr
+
+    # Ensure no exception on empty set
+    pr.kill_all_best_effort()
+
+
+def test_process_registry_kill_all_best_effort_windows_noop_when_taskkill_missing(
+    monkeypatch,
+):
+    from cli import process_registry as pr
+
+    # Simulate windows path in a stable way.
+    monkeypatch.setattr(pr, "_pids", {12345})
+    monkeypatch.setattr(os, "name", "nt", raising=False)
+
+    # If taskkill isn't callable, we still should not crash.
+    import subprocess
+
+    def _boom(*args, **kwargs):
+        raise FileNotFoundError("taskkill missing")
+
+    monkeypatch.setattr(subprocess, "run", _boom)
+    pr.kill_all_best_effort()