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/docs/COVERAGE.md

@@ -2,7 +2,7 @@
 
 > Tracking progress towards Claude Code-like functionality
 
-## Current Status: ~70% Complete
+## Current Status: ~80% Complete
 
 Last updated: 2026-01-11
 
@@ -68,16 +68,19 @@ Last updated: 2026-01-11
 | Markdown rendering | ✅ | Rich markdown output |
 | Streaming display | ✅ | Real-time token output with `--stream` flag |
 
-### Phase 4: Agentic Loop ⚠️ Partial
+### Phase 4: Agentic Loop ✅ Complete
 
 | Component | Status | Notes |
 |-----------|--------|-------|
 | `webber-cli chat` command | ✅ | Interactive mode with streaming |
 | `webber-cli explore` command | ✅ | One-shot query with streaming |
 | `SessionState` dataclass | ✅ | Basic context tracking |
-| `AgenticLoop` class | ⚠️ | Basic implementation, not fully utilized |
-| Conversation history | ❌ | Not persisted between turns in CLI |
-| Context management | ❌ | No token counting or summarization |
+| `AgenticLoop` class | ✅ | Basic implementation |
+| Conversation persistence | ✅ | SQLAlchemy async with SQLite/PostgreSQL |
+| Context summarization | ✅ | Token counting (litellm) + auto-summarization |
+| Conversation API | ✅ | `/conversations/` REST endpoints |
+
+**Database:** SQLite (dev) or PostgreSQL (prod), async via SQLAlchemy 2.0
 
 ### Phase 5: REST API ✅ Complete
 
@@ -109,9 +112,9 @@ Last updated: 2026-01-11
 | Feature | Category | Description | Complexity |
 |---------|----------|-------------|------------|
 | ~~**Plan Agent**~~ | Agents | ✅ Design implementation approaches | High |
-| **Task Agent** | Agents | Autonomous multi-step execution | High |
-| **Context summarization** | Infrastructure | Compress history at token limit | High |
-| **Conversation persistence** | CLI | Multi-turn memory in chat mode | Medium |
+| ~~**Task Agent**~~ | Agents | ✅ Autonomous multi-step execution | High |
+| ~~**Context summarization**~~ | Infrastructure | ✅ Token counting + auto-summarization | High |
+| ~~**Conversation persistence**~~ | Infrastructure | ✅ SQLAlchemy async database layer | Medium |
 
 ### Medium Priority
 
@@ -145,10 +148,15 @@ Last updated: 2026-01-11
 | Tool unit tests | 109 | 109 | ✅ |
 | API tests | 11 | 11 | ✅ |
 | Plan agent tests | 15 | 15 | ✅ |
+| Task agent tests | 15 | 15 | ✅ |
+| Conversation tests | 19 | 19 | ✅ |
+| Token tests | 6 | 6 | ✅ |
 | Security tests | 14 | 14 | ✅ |
 | Integration tests | 10 | 10 | ✅ Agent + real LLM |
 | E2E tests | 12 | 12 | ✅ Full API workflow |
 
+**Total: 176 tests passing**
+
 **Test breakdown:**
 - Read/Glob/Grep tools: 17 tests
 - Edit/Write tools: 22 tests
@@ -157,6 +165,9 @@ Last updated: 2026-01-11
 - Gitignore filtering: 10 tests
 - API endpoints: 11 tests
 - Plan agent: 15 tests
+- Task agent: 15 tests
+- Conversations: 19 tests
+- Tokens: 6 tests
 - Security: 14 tests
 - Health checks: 2 tests
 - Integration (LLM): 10 tests
@@ -183,9 +194,9 @@ pytest tests/ --run-integration --run-e2e
 
 1. **Model hallucination** - Mistral Nemo sometimes makes up file contents instead of using actual tool results.
 
-2. **No conversation memory** - CLI chat mode doesn't persist context between sessions.
+2. **Temperature setting** - Changed from 0.0 to 0.3 for Mistral Nemo compatibility, may affect determinism.
 
-3. **Temperature setting** - Changed from 0.0 to 0.3 for Mistral Nemo compatibility, may affect determinism.
+3. **SQLAlchemy deprecation** - `datetime.utcnow()` deprecation warning from SQLAlchemy.
 
 ---
 
@@ -231,6 +242,17 @@ curl -X POST http://localhost:8095/agents/run \
 curl -N http://localhost:8095/agents/stream \
   -H "Content-Type: application/json" \
   -d '{"agent_type":"explore","prompt":"find config files","working_dir":"."}'
+
+# Conversation API (stateful multi-turn)
+curl -X POST http://localhost:8095/conversations/ \
+  -H "Content-Type: application/json" \
+  -H "X-API-Key: dev-key" \
+  -d '{"agent_type":"explore","working_dir":"."}'
+
+curl -X POST http://localhost:8095/conversations/{id}/messages \
+  -H "Content-Type: application/json" \
+  -H "X-API-Key: dev-key" \
+  -d '{"content":"find all Python files"}'
 ```
 
 ---