chore: remainder — backend test infra, agent config, docker, i18n, frontend ui

- Backend: alembic env, config manager/models, dependencies, translate plugin
- Backend tests: async_sync_regression, integration tests, git services, test_agent
- Docker: docker-compose.yml updates
- Agent: qa-tester.md update, semantics-testing SKILL.md update
- Frontend: TopNavbar, sidebarNavigation, FeaturesSettings, FeatureGate
- i18n: assistant.json en/ru locale updates
- New: frontend/src/lib/components/agent/ directory

backend/tests/test_agent/test_model_fixtures.py

@@ -0,0 +1,130 @@
+# #region TestAgentChat.ModelFixtures [C:2] [TYPE Module] [SEMANTICS test,agent,fixtures,model]
+# @BRIEF Materialize model fixtures from JSON — verify fixture structure matches expected.
+# @RELATION BINDS_TO -> [AgentChat.Model]
+import json
+from pathlib import Path
+
+import pytest
+
+FIXTURES_DIR = Path(__file__).resolve().parent.parent.parent.parent / "specs" / "033-gradio-agent-chat" / "fixtures" / "model"
+
+
+# #region TestAgentChat.ModelFixtures.SendMessageValid [C:2] [TYPE Function] [SEMANTICS test,fixture,send]
+# @BRIEF FX_AgentChat.Model.SendMessage.Valid — verify fixture structure.
+def test_fixture_send_message_valid():
+    """Load send_message_valid fixture and verify structural integrity."""
+    fixture_path = FIXTURES_DIR / "send_message_valid.json"
+    assert fixture_path.exists(), f"Fixture not found: {fixture_path}"
+
+    with open(fixture_path) as f:
+        fixture = json.load(f)
+
+    assert fixture["fixture_id"] == "FX_AgentChat.Model.SendMessage.Valid"
+    assert fixture["verifies"] == "AgentChat.Model"
+    assert fixture["invariant"] == "StreamingStateGatesInput"
+    assert fixture["input"]["action"] == "sendMessage"
+    assert fixture["input"]["state_before"]["streamingState"] == "idle"
+    assert fixture["expected"]["state_after"]["streamingState"] == "streaming"
+    assert fixture["expected"]["state_after"]["isInputLocked"] is True
+    assert fixture["expected"]["state_after"]["error"] is None
+# #endregion TestAgentChat.ModelFixtures.SendMessageValid
+
+
+# #region TestAgentChat.ModelFixtures.CancelGeneration [C:2] [TYPE Function] [SEMANTICS test,fixture,cancel]
+# @BRIEF FX_AgentChat.Model.CancelGeneration — verify cancel fixture structure.
+def test_fixture_cancel_generation():
+    """Load cancel_generation fixture and verify structural integrity."""
+    fixture_path = FIXTURES_DIR / "cancel_generation.json"
+    assert fixture_path.exists(), f"Fixture not found: {fixture_path}"
+
+    with open(fixture_path) as f:
+        fixture = json.load(f)
+
+    assert fixture["fixture_id"] == "FX_AgentChat.Model.CancelGeneration"
+    assert fixture["edge"] == "cancel_during_streaming"
+    assert fixture["input"]["action"] == "cancelGeneration"
+    expected = fixture["expected"]["state_after"]
+    assert expected["streamingState"] == "idle"
+    assert expected["isInputLocked"] is False
+    assert "partialText" in expected
+# #endregion TestAgentChat.ModelFixtures.CancelGeneration
+
+
+# #region TestAgentChat.ModelFixtures.ResumeConfirm [C:2] [TYPE Function] [SEMANTICS test,fixture,confirm]
+# @BRIEF FX_AgentChat.Model.ResumeConfirm — verify resume confirm fixture.
+def test_fixture_resume_confirm():
+    """Load resume_confirm fixture and verify structural integrity."""
+    fixture_path = FIXTURES_DIR / "resume_confirm.json"
+    assert fixture_path.exists(), f"Fixture not found: {fixture_path}"
+
+    with open(fixture_path) as f:
+        fixture = json.load(f)
+
+    assert fixture["fixture_id"] == "FX_AgentChat.Model.ResumeConfirm"
+    assert fixture["edge"] == "confirm_from_awaiting"
+    assert fixture["input"]["action"] == "resumeConfirm"
+    assert fixture["input"]["args"] == ["confirm"]
+    expected = fixture["expected"]["state_after"]
+    assert expected["streamingState"] == "streaming"
+    assert expected["pendingThreadId"] is None
+# #endregion TestAgentChat.ModelFixtures.ResumeConfirm
+
+
+# #region TestAgentChat.ModelFixtures.ResumeDeny [C:2] [TYPE Function] [SEMANTICS test,fixture,deny]
+# @BRIEF FX_AgentChat.Model.ResumeDeny — verify resume deny fixture.
+def test_fixture_resume_deny():
+    """Load resume_deny fixture and verify structural integrity."""
+    fixture_path = FIXTURES_DIR / "resume_deny.json"
+    assert fixture_path.exists(), f"Fixture not found: {fixture_path}"
+
+    with open(fixture_path) as f:
+        fixture = json.load(f)
+
+    assert fixture["fixture_id"] == "FX_AgentChat.Model.ResumeDeny"
+    assert fixture["edge"] == "deny_from_awaiting"
+    assert fixture["input"]["action"] == "resumeConfirm"
+    assert fixture["input"]["args"] == ["deny"]
+    expected = fixture["expected"]["state_after"]
+    assert expected["streamingState"] == "idle"
+    assert expected["pendingThreadId"] is None
+# #endregion TestAgentChat.ModelFixtures.ResumeDeny
+
+
+# #region TestAgentChat.ModelFixtures.RejectedWebSocket [C:2] [TYPE Function] [SEMANTICS test,fixture,rejected]
+# @BRIEF FX_AgentChat.Model.RejectedPath — verify no WebSocket resurrection.
+def test_fixture_rejected_websocket():
+    """Verify no WebSocket resurrection in AgentChatModel."""
+    fixture_path = FIXTURES_DIR / "rejected_websocket.json"
+    assert fixture_path.exists(), f"Fixture not found: {fixture_path}"
+
+    with open(fixture_path) as f:
+        fixture = json.load(f)
+
+    assert fixture["fixture_id"] == "FX_AgentChat.Model.RejectedPath"
+    assert fixture["invariant"] == "NoWebSocketImports"
+    assert fixture["edge"] == "rejected_path"
+    assert "No 'WebSocket'" in fixture["expected"]["assertions"][0]
+
+    # Read the actual model source
+    model_path = Path(__file__).resolve().parent.parent.parent.parent / "frontend" / "src" / "lib" / "models" / "AgentChatModel.svelte.ts"
+    source = model_path.read_text()
+
+    # Verify no WebSocket imports (not just the word — it's in comments as @REJECTED)
+    assertions = fixture["expected"]["assertions"]
+    for assertion in assertions:
+        if "WebSocket" in assertion:
+            # Check for actual WebSocket import (import WebSocket, from ... import ... WebSocket)
+            for line in source.split("\n"):
+                stripped = line.strip()
+                if stripped.startswith("import") and "WebSocket" in stripped:
+                    pytest.fail(f"FAIL: {assertion} — found WebSocket import: {stripped}")
+                if stripped.startswith("from") and "WebSocket" in stripped:
+                    pytest.fail(f"FAIL: {assertion} — found WebSocket import: {stripped}")
+        if "tabRole" in assertion:
+            assert "tabRole" not in source, f"FAIL: {assertion}"
+        if "follower_notify" in assertion:
+            assert "follower_notify" not in source, f"FAIL: {assertion}"
+        if "takeoverSession" in assertion:
+            assert "takeoverSession" not in source, f"FAIL: {assertion}"
+# #endregion TestAgentChat.ModelFixtures.RejectedWebSocket
+# #endregion TestAgentChat.ModelFixtures