fix(cli): synchronize HERMES_SESSION_ID across environment and contextvar during session switches

tests/cli/test_branch_command.py

@@ -168,6 +168,25 @@ class TestBranchCommandCLI:
 
         assert cli_instance._resumed is True
 
+    def test_branch_rotates_hermes_session_id_env_and_context(self, cli_instance, session_db):
+        """Branching must update process-local session-id readers too."""
+        from cli import HermesCLI
+        from gateway.session_context import _UNSET, _VAR_MAP, get_session_env
+
+        old_session_id = cli_instance.session_id
+        os.environ["HERMES_SESSION_ID"] = old_session_id
+        _VAR_MAP["HERMES_SESSION_ID"].set(old_session_id)
+
+        try:
+            HermesCLI._handle_branch_command(cli_instance, "/branch")
+
+            assert cli_instance.session_id != old_session_id
+            assert os.environ["HERMES_SESSION_ID"] == cli_instance.session_id
+            assert get_session_env("HERMES_SESSION_ID") == cli_instance.session_id
+        finally:
+            os.environ.pop("HERMES_SESSION_ID", None)
+            _VAR_MAP["HERMES_SESSION_ID"].set(_UNSET)
+
     def test_branch_fires_on_session_switch_hook(self, cli_instance, session_db):
         """The /branch command must notify memory providers of the rotation.
 

tests/cli/test_cli_init.py

@@ -333,6 +333,33 @@ class TestHistoryDisplay:
         assert "Checking Running Hermes Agent" in output
         assert "Use /resume <session id or title> to continue" in output
 
+    def test_resume_updates_hermes_session_id_env_and_context(self, tmp_path):
+        from gateway.session_context import _UNSET, _VAR_MAP, get_session_env
+        from hermes_state import SessionDB
+
+        cli = _make_cli()
+        cli.session_id = "current_session"
+        cli.conversation_history = []
+        cli.agent = None
+        cli._session_db = SessionDB(db_path=tmp_path / "state.db")
+        cli._session_db.create_session("current_session", "cli")
+        cli._session_db.create_session("target_session", "cli")
+        cli._session_db.append_message("target_session", "user", "hello from resumed session")
+
+        os.environ["HERMES_SESSION_ID"] = "current_session"
+        _VAR_MAP["HERMES_SESSION_ID"].set("current_session")
+
+        try:
+            cli._handle_resume_command("/resume target_session")
+
+            assert cli.session_id == "target_session"
+            assert os.environ["HERMES_SESSION_ID"] == "target_session"
+            assert get_session_env("HERMES_SESSION_ID") == "target_session"
+        finally:
+            cli._session_db.close()
+            os.environ.pop("HERMES_SESSION_ID", None)
+            _VAR_MAP["HERMES_SESSION_ID"].set(_UNSET)
+
     def test_sessions_command_no_args_lists_recent_sessions(self, capsys):
         """/sessions with no args prints the recent-sessions table (TUI parity).
 

tests/cli/test_cli_new_session.py

@@ -8,6 +8,8 @@ import sys
 from datetime import datetime, timedelta
 from unittest.mock import MagicMock, patch
 
+import pytest
+
 from hermes_state import SessionDB
 from tools.todo_tool import TodoStore
 
@@ -138,6 +140,15 @@ def _prepare_cli_with_active_session(tmp_path):
     return cli
 
 
+@pytest.fixture(autouse=True)
+def _reset_session_id_context():
+    from gateway.session_context import _UNSET, _VAR_MAP
+
+    yield
+    os.environ.pop("HERMES_SESSION_ID", None)
+    _VAR_MAP["HERMES_SESSION_ID"].set(_UNSET)
+
+
 def test_new_command_creates_real_fresh_session_and_resets_agent_state(tmp_path):
     cli = _prepare_cli_with_active_session(tmp_path)
     old_session_id = cli.session_id
@@ -164,6 +175,21 @@ def test_new_command_creates_real_fresh_session_and_resets_agent_state(tmp_path)
     cli.agent._invalidate_system_prompt.assert_called_once()
 
 
+def test_new_command_rotates_hermes_session_id_env_and_context(tmp_path):
+    from gateway.session_context import _VAR_MAP, get_session_env
+
+    cli = _prepare_cli_with_active_session(tmp_path)
+    old_session_id = cli.session_id
+    os.environ["HERMES_SESSION_ID"] = old_session_id
+    _VAR_MAP["HERMES_SESSION_ID"].set(old_session_id)
+
+    cli.process_command("/new")
+
+    assert cli.session_id != old_session_id
+    assert os.environ["HERMES_SESSION_ID"] == cli.session_id
+    assert get_session_env("HERMES_SESSION_ID") == cli.session_id
+
+
 def test_reset_command_is_alias_for_new_session(tmp_path):
     cli = _prepare_cli_with_active_session(tmp_path)
     old_session_id = cli.session_id