feat: h/l focus navigation between project and session columns

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_tui.py

@@ -1983,3 +1983,35 @@ def test_policy_reflects_suboptions_when_sandbox_on():
     assert policy is not None
     assert policy.fs == "ro"
     assert policy.net is False
+
+
+# ---------------------------------------------------------------------------
+# Task 3: h/l column focus navigation
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+async def test_hl_focus_bindings_exist():
+    bindings = {b.key: b for b in HqtApp.BINDINGS}
+    assert bindings["h"].action == "focus_projects"
+    assert bindings["l"].action == "focus_sessions"
+
+
+@pytest.mark.asyncio
+async def test_h_focuses_projects_l_focuses_sessions(tmp_path):
+    app = HqtApp()
+    async with app.run_test(size=(120, 40)) as pilot:
+        d = tmp_path / "hl-proj"
+        d.mkdir()
+        app._project_service.create("hl", str(d))
+        app._load_projects()
+        await app.workers.wait_for_complete()
+        await pilot.pause()
+
+        await pilot.press("l")
+        await pilot.pause()
+        assert app.focused is app.query_one("#session-list")
+
+        await pilot.press("h")
+        await pilot.pause()
+        assert app.focused is app.query_one("#project-list")