feat: add conversation persistence and context management layer

- SQLAlchemy async database layer (SQLite dev, PostgreSQL prod)
- Conversation and Message models with UUID primary keys
- Token counting utilities using litellm
- Context summarization at 80% token threshold
- REST API endpoints for multi-turn conversations
- 19 conversation tests, 6 token tests (176 total passing)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

webber-api/tests/test_conversations.py

@@ -0,0 +1,299 @@
+"""
+Tests for conversations domain.
+
+Tests conversation CRUD, context building, and API endpoints.
+"""
+import pytest
+from uuid import uuid4
+
+from src.domains.conversations.models import Conversation, Message
+from src.domains.conversations.schemas import (
+    CreateConversationRequest,
+    AddMessageRequest,
+    ConversationResponse,
+    MessageResponse,
+)
+
+
+class TestConversationModels:
+    """Tests for conversation database models."""
+
+    def test_conversation_creation(self):
+        """Test Conversation model creation with explicit values."""
+        conv = Conversation(
+            user_id="test-user",
+            agent_type="explore",
+            working_dir=".",
+            total_tokens=0,
+        )
+        assert conv.user_id == "test-user"
+        assert conv.agent_type == "explore"
+        assert conv.working_dir == "."
+        assert conv.total_tokens == 0
+
+    def test_conversation_with_values(self):
+        """Test Conversation with explicit values."""
+        conv = Conversation(
+            user_id="test-user",
+            agent_type="plan",
+            working_dir="/tmp/project",
+            title="Test Conversation",
+        )
+        assert conv.agent_type == "plan"
+        assert conv.working_dir == "/tmp/project"
+        assert conv.title == "Test Conversation"
+
+    def test_message_creation(self):
+        """Test Message model creation with explicit values."""
+        msg = Message(
+            conversation_id=uuid4(),
+            role="user",
+            content="Hello",
+            token_count=0,
+            is_summary=False,
+        )
+        assert msg.role == "user"
+        assert msg.content == "Hello"
+        assert msg.token_count == 0
+        assert msg.is_summary is False
+
+    def test_message_repr(self):
+        """Test Message string representation."""
+        msg = Message(
+            conversation_id=uuid4(),
+            role="user",
+            content="This is a test message",
+        )
+        repr_str = repr(msg)
+        assert "user" in repr_str
+        assert "This is a test" in repr_str
+
+
+class TestConversationSchemas:
+    """Tests for Pydantic schemas."""
+
+    def test_create_request_defaults(self):
+        """Test CreateConversationRequest defaults."""
+        request = CreateConversationRequest()
+        assert request.agent_type == "explore"
+        assert request.working_dir == "."
+        assert request.title is None
+
+    def test_create_request_custom(self):
+        """Test CreateConversationRequest with values."""
+        request = CreateConversationRequest(
+            agent_type="task",
+            working_dir="/home/user/project",
+            title="My Task",
+        )
+        assert request.agent_type == "task"
+        assert request.working_dir == "/home/user/project"
+        assert request.title == "My Task"
+
+    def test_add_message_request_valid(self):
+        """Test AddMessageRequest validation."""
+        request = AddMessageRequest(content="Hello, world!")
+        assert request.content == "Hello, world!"
+
+    def test_add_message_request_empty_fails(self):
+        """Test that empty content fails validation."""
+        with pytest.raises(ValueError):
+            AddMessageRequest(content="")
+
+
+class TestConversationAPI:
+    """Tests for conversation API endpoints."""
+
+    @pytest.mark.anyio
+    async def test_create_conversation(self, auth_client):
+        """Test creating a conversation."""
+        response = await auth_client.post(
+            "/conversations/",
+            json={"agent_type": "explore", "working_dir": "."}
+        )
+        assert response.status_code == 201
+        data = response.json()
+        assert "id" in data
+        assert data["agent_type"] == "explore"
+        assert data["total_tokens"] == 0
+
+    @pytest.mark.anyio
+    async def test_create_conversation_with_title(self, auth_client):
+        """Test creating a conversation with title."""
+        response = await auth_client.post(
+            "/conversations/",
+            json={
+                "agent_type": "plan",
+                "working_dir": "/tmp",
+                "title": "Planning Session"
+            }
+        )
+        assert response.status_code == 201
+        data = response.json()
+        assert data["title"] == "Planning Session"
+        assert data["agent_type"] == "plan"
+
+    @pytest.mark.anyio
+    async def test_list_conversations_empty(self, auth_client):
+        """Test listing conversations when empty."""
+        response = await auth_client.get("/conversations/")
+        assert response.status_code == 200
+        data = response.json()
+        assert "conversations" in data
+        assert "total" in data
+
+    @pytest.mark.anyio
+    async def test_get_conversation_not_found(self, auth_client):
+        """Test getting non-existent conversation."""
+        fake_id = uuid4()
+        response = await auth_client.get(f"/conversations/{fake_id}")
+        assert response.status_code == 404
+
+    @pytest.mark.anyio
+    async def test_delete_conversation_not_found(self, auth_client):
+        """Test deleting non-existent conversation."""
+        fake_id = uuid4()
+        response = await auth_client.delete(f"/conversations/{fake_id}")
+        assert response.status_code == 404
+
+    @pytest.mark.anyio
+    async def test_add_message_not_found(self, auth_client):
+        """Test adding message to non-existent conversation."""
+        fake_id = uuid4()
+        response = await auth_client.post(
+            f"/conversations/{fake_id}/messages",
+            json={"content": "Hello"}
+        )
+        assert response.status_code == 404
+
+
+class TestConversationService:
+    """Tests for ConversationService business logic."""
+
+    @pytest.mark.anyio
+    async def test_context_prompt_no_history(self):
+        """Test building context prompt with no history."""
+        from src.domains.conversations.service import ConversationService
+        from unittest.mock import MagicMock
+
+        # Create mock session
+        mock_session = MagicMock()
+        service = ConversationService(mock_session)
+
+        prompt = service.build_context_prompt([], "What files are here?")
+
+        assert "<current_request>" in prompt
+        assert "What files are here?" in prompt
+        assert "<recent_conversation>" not in prompt
+        assert "<conversation_summary>" not in prompt
+
+    @pytest.mark.anyio
+    async def test_context_prompt_with_history(self):
+        """Test building context prompt with message history."""
+        from src.domains.conversations.service import ConversationService
+        from src.domains.conversations.models import Message
+        from unittest.mock import MagicMock
+
+        mock_session = MagicMock()
+        service = ConversationService(mock_session)
+
+        messages = [
+            Message(
+                conversation_id=uuid4(),
+                role="user",
+                content="Find Python files",
+            ),
+            Message(
+                conversation_id=uuid4(),
+                role="assistant",
+                content="Found 10 Python files.",
+            ),
+        ]
+
+        prompt = service.build_context_prompt(messages, "Show the largest")
+
+        assert "<recent_conversation>" in prompt
+        assert "USER: Find Python files" in prompt
+        assert "ASSISTANT: Found 10 Python files" in prompt
+        assert "<current_request>" in prompt
+        assert "Show the largest" in prompt
+
+    @pytest.mark.anyio
+    async def test_context_prompt_with_summary(self):
+        """Test building context prompt with summary message."""
+        from src.domains.conversations.service import ConversationService
+        from src.domains.conversations.models import Message
+        from unittest.mock import MagicMock
+
+        mock_session = MagicMock()
+        service = ConversationService(mock_session)
+
+        messages = [
+            Message(
+                conversation_id=uuid4(),
+                role="summary",
+                content="Previously discussed: project setup",
+                is_summary=True,
+            ),
+            Message(
+                conversation_id=uuid4(),
+                role="user",
+                content="Now what?",
+            ),
+        ]
+
+        prompt = service.build_context_prompt(messages, "Continue")
+
+        assert "<conversation_summary>" in prompt
+        assert "Previously discussed: project setup" in prompt
+
+
+class TestSummarization:
+    """Tests for conversation summarization."""
+
+    def test_format_messages_for_summary(self):
+        """Test formatting messages for summarization."""
+        from src.domains.conversations.summarize import format_messages_for_summary
+        from src.domains.conversations.models import Message
+
+        messages = [
+            Message(
+                conversation_id=uuid4(),
+                role="user",
+                content="Hello",
+            ),
+            Message(
+                conversation_id=uuid4(),
+                role="assistant",
+                content="Hi there!",
+            ),
+        ]
+
+        formatted = format_messages_for_summary(messages)
+
+        assert "USER: Hello" in formatted
+        assert "ASSISTANT: Hi there!" in formatted
+
+    def test_format_messages_with_summary(self):
+        """Test formatting messages that include a summary."""
+        from src.domains.conversations.summarize import format_messages_for_summary
+        from src.domains.conversations.models import Message
+
+        messages = [
+            Message(
+                conversation_id=uuid4(),
+                role="summary",
+                content="Previous context summary",
+                is_summary=True,
+            ),
+            Message(
+                conversation_id=uuid4(),
+                role="user",
+                content="Continue",
+            ),
+        ]
+
+        formatted = format_messages_for_summary(messages)
+
+        assert "[Previous Summary]" in formatted
+        assert "Previous context summary" in formatted

webber-api/tests/test_tokens.py

@@ -0,0 +1,90 @@
+"""
+Tests for token counting utilities.
+"""
+import pytest
+
+from src.shared.tokens import count_tokens, count_message_tokens, estimate_tokens
+
+
+class TestTokenCounting:
+    """Tests for token counting functions."""
+
+    def test_estimate_tokens_basic(self):
+        """Test basic token estimation."""
+        text = "Hello world"
+        tokens = estimate_tokens(text)
+        # ~4 chars per token
+        assert tokens == len(text) // 4
+
+    def test_estimate_tokens_empty(self):
+        """Test estimation with empty string."""
+        assert estimate_tokens("") == 0
+
+    def test_estimate_tokens_long_text(self):
+        """Test estimation with longer text."""
+        text = "a" * 400
+        tokens = estimate_tokens(text)
+        assert tokens == 100
+
+    def test_count_tokens_basic(self):
+        """Test actual token counting."""
+        text = "Hello, how are you today?"
+        tokens = count_tokens(text)
+        # Should return reasonable token count
+        assert tokens > 0
+        assert tokens < len(text)  # Should be fewer tokens than characters
+
+    def test_count_tokens_empty(self):
+        """Test counting empty string."""
+        tokens = count_tokens("")
+        assert tokens == 0
+
+    def test_count_message_tokens_single(self):
+        """Test counting tokens in single message."""
+        messages = [{"role": "user", "content": "Hello"}]
+        tokens = count_message_tokens(messages)
+        assert tokens > 0
+
+    def test_count_message_tokens_multiple(self):
+        """Test counting tokens in multiple messages."""
+        messages = [
+            {"role": "user", "content": "Hello, how are you?"},
+            {"role": "assistant", "content": "I'm doing well, thank you!"},
+        ]
+        tokens = count_message_tokens(messages)
+        # Should be more than single message
+        single_tokens = count_message_tokens([messages[0]])
+        assert tokens > single_tokens
+
+    def test_count_message_tokens_empty_list(self):
+        """Test counting empty message list."""
+        tokens = count_message_tokens([])
+        # litellm may return small overhead even for empty list
+        assert tokens < 10
+
+
+class TestTokenCountingAccuracy:
+    """Tests for token counting accuracy."""
+
+    def test_code_tokens_reasonable(self):
+        """Test that code is tokenized reasonably."""
+        code = """
+def hello_world():
+    print("Hello, World!")
+    return True
+"""
+        tokens = count_tokens(code)
+        # Code should have reasonable token count
+        assert 10 < tokens < 100
+
+    def test_special_characters(self):
+        """Test tokenization of special characters."""
+        text = "Hello! @#$%^&*() World?"
+        tokens = count_tokens(text)
+        assert tokens > 0
+
+    def test_unicode_text(self):
+        """Test tokenization of unicode text."""
+        text = "Hello 世界 🌍"
+        tokens = count_tokens(text)
+        assert tokens > 0