diff --git a/hermes_cli/cli_commands_mixin.py b/hermes_cli/cli_commands_mixin.py
index be5fb8e92..70f82f2ea 100644
--- a/hermes_cli/cli_commands_mixin.py
+++ b/hermes_cli/cli_commands_mixin.py
@@ -712,6 +712,14 @@ class CLICommandsMixin:
             return
 
         old_session_id = self.session_id
+        # Flush un-persisted messages before ending the old session (#47202).
+        if self.agent:
+            try:
+                self.agent._flush_messages_to_session_db(
+                    self.conversation_history
+                )
+            except Exception:
+                pass
         # End current session
         try:
             self._session_db.end_session(self.session_id, "resumed_other")
@@ -851,6 +859,15 @@ class CLICommandsMixin:
         # Save the current session's state before branching
         parent_session_id = self.session_id
 
+        # Flush un-persisted messages before ending the old session (#47202).
+        if self.agent:
+            try:
+                self.agent._flush_messages_to_session_db(
+                    self.conversation_history
+                )
+            except Exception:
+                pass
+
         # End the old session
         try:
             self._session_db.end_session(self.session_id, "branched")
diff --git a/tests/cli/test_branch_command.py b/tests/cli/test_branch_command.py
index 8f8a70749..9c14243cf 100644
--- a/tests/cli/test_branch_command.py
+++ b/tests/cli/test_branch_command.py
@@ -240,3 +240,21 @@ class TestBranchCommandDef:
         from hermes_cli.commands import COMMAND_REGISTRY
         branch = next(c for c in COMMAND_REGISTRY if c.name == "branch")
         assert branch.category == "Session"
+
+
+class TestBranchFlushesBeforeEndSession:
+    """Regression for #47202: /branch must flush un-persisted messages to
+    the session DB before ending the old session, just like /new and
+    compress_context() already do."""
+
+    def test_branch_flushes_when_agent_present(self, cli_instance, session_db):
+        from cli import HermesCLI
+
+        agent = MagicMock()
+        cli_instance.agent = agent
+
+        HermesCLI._handle_branch_command(cli_instance, "/branch")
+
+        agent._flush_messages_to_session_db.assert_called_once_with(
+            cli_instance.conversation_history
+        )
diff --git a/tests/cli/test_cli_resume_command.py b/tests/cli/test_cli_resume_command.py
index b062f9326..299d5fad2 100644
--- a/tests/cli/test_cli_resume_command.py
+++ b/tests/cli/test_cli_resume_command.py
@@ -321,3 +321,33 @@ class TestRestoreSessionCwdMarkup:
             assert "Working directory" in printed or "working" in printed.lower()
         finally:
             os.chdir(original_cwd)
+
+
+class TestResumeFlushesBeforeEndSession:
+    """Regression for #47202: /resume must flush un-persisted messages to
+    the session DB before ending the old session, just like /new and
+    compress_context() already do."""
+
+    def test_resume_flushes_when_agent_present(self):
+        cli_obj = _make_cli()
+        cli_obj.conversation_history = [
+            {"role": "user", "content": "hello"},
+            {"role": "assistant", "content": "hi"},
+        ]
+        agent = MagicMock()
+        cli_obj.agent = agent
+
+        cli_obj._session_db.get_session.return_value = {"id": "target", "title": "T"}
+        cli_obj._session_db.get_messages_as_conversation.return_value = []
+        cli_obj._session_db.resolve_resume_session_id.return_value = "target"
+
+        with (
+            patch("hermes_cli.main._resolve_session_by_name_or_id", return_value="target"),
+            patch("cli._cprint"),
+        ):
+            cli_obj._handle_resume_command("/resume target")
+
+        agent._flush_messages_to_session_db.assert_called_once_with(
+            [{"role": "user", "content": "hello"}, {"role": "assistant", "content": "hi"}]
+        )
+        cli_obj._session_db.end_session.assert_called_once()