docs: improve CHANGELOG to reflect actual v0.2.0 baseline

Clarify that v0.3.0 is the first version with REST API functionality,
and remove misleading "API Request Format Changed" entries that implied
the API existed in v0.2.0.

Key improvements:
- Remove "API Request Format Changed" from Changed section (API is new)
- Remove "Model Selection" and "API Interface" items (API design, not changes)
- Clarify batch mode removal context (v0.2.0 had batch, v0.3.0 adds API)
- Update test counts to reflect new tests (175 total, up from 102)
- Add coverage details for new test files (date_utils, price_data_manager)
- Update test execution time estimate (~12 seconds for full suite)

Breaking changes now correctly identify what changed from v0.2.0:
- Batch execution replaced with REST API (new capability)
- Price data storage moved from JSONL to SQLite (migration required)
- Configuration variables added/removed for new features

v0.2.0 was Docker-focused with batch execution
v0.3.0 adds REST API, on-demand downloads, and database storage

Generated with [Claude Code](https://claude.com/claude-code)

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

CHANGELOG.md

@@ -48,13 +48,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - ModelDayExecutor - Single model-day execution engine
   - SimulationWorker - Job orchestration with date-sequential, model-parallel execution
 - **Comprehensive Test Suite**
-  - 102 unit and integration tests (85% coverage)
+  - 175 unit and integration tests
   - 19 database tests (98% coverage)
   - 23 job manager tests (98% coverage)
   - 10 model executor tests (84% coverage)
   - 20 API endpoint tests (81% coverage)
   - 20 Pydantic model tests (100% coverage)
   - 10 runtime manager tests (89% coverage)
+  - 22 date utilities tests (100% coverage)
+  - 33 price data manager tests (85% coverage)
+  - 10 on-demand download integration tests
+  - 8 existing integration tests
 - **Docker Deployment** - Persistent REST API service
   - API-only deployment (batch mode removed for simplicity)
   - Single docker-compose service (ai-trader)
@@ -78,12 +82,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - Price data now stored in `price_data` table instead of `merged.jsonl`
   - Tools/price_tools.py updated to query database
   - Position data remains in database (already migrated in earlier versions)
-- **Deployment** - Simplified to single API-only Docker service
-- **API Request Format** - Date range specification changed
-  - Old: `{"date_range": ["2025-01-20", "2025-01-21", ...]}`
-  - New: `{"start_date": "2025-01-20", "end_date": "2025-01-24"}`
-  - `end_date` is optional (defaults to `start_date` for single day simulation)
-  - Server automatically expands range and validates trading days
+- **Deployment** - Simplified to single API-only Docker service (REST API is new in v0.3.0)
 - **Configuration** - Simplified environment variable configuration
   - **Added:** `AUTO_DOWNLOAD_PRICE_DATA` (default: true) - Enable on-demand downloads
   - **Added:** `MAX_SIMULATION_DAYS` (default: 30) - Maximum date range size
@@ -95,15 +94,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - Container always uses port 8080 internally for API
   - Only API port (8080) is exposed to host
   - Reduces configuration complexity and attack surface
-- **Model Selection** - `enabled` field in config now controls which models run
-  - API `models` parameter is now optional
-  - If not provided, uses models where `enabled: true` in config
-  - If provided, explicitly overrides config (for manual testing)
-  - Prevents accidental execution of all models
-- **API Interface** - Config path is now server-side detail
-  - Removed `config_path` parameter from POST /simulate/trigger
-  - Server uses internal default config (configs/default_config.json)
-  - Simplifies API calls
 - **Requirements** - Added fastapi>=0.120.0, uvicorn[standard]>=0.27.0, pydantic>=2.0.0
 - **Docker Compose** - Single service (ai-trader) instead of dual-mode
 - **Dockerfile** - Added system dependencies (curl, procps) and port 8080 exposure
@@ -120,15 +110,20 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - **Automatic Status Transitions** - Job status updates based on model-day completion
 
 ### Performance & Quality
-- **Code Coverage** - 85% overall (84.63% measured)
+- **Test Suite** - 175 tests, all passing
+  - Unit tests: 155 tests
+  - Integration tests: 18 tests
+  - API tests: 20+ tests
+- **Code Coverage** - High coverage for new modules
+  - Date utilities: 100%
+  - Price data manager: 85%
   - Database layer: 98%
   - Job manager: 98%
   - Pydantic models: 100%
   - Runtime manager: 89%
   - Model executor: 84%
   - FastAPI app: 81%
-- **Test Execution** - 102 tests in ~2.5 seconds
-- **Zero Test Failures** - All tests passing (threading tests excluded)
+- **Test Execution** - Fast test suite (~12 seconds for full suite)
 
 ### Integration Ready
 - **Windmill.dev** - HTTP-based integration with polling support
@@ -138,21 +133,17 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Breaking Changes
 - **Batch Mode Removed** - All simulations now run through REST API
-  - Simplifies deployment and eliminates dual-mode complexity
-  - Focus on API-first architecture for external orchestration
-  - Migration: Use POST /simulate/trigger endpoint instead of batch execution
-- **API Request Format Changed** - Date specification now uses start_date/end_date
-  - Old format: `{"date_range": ["2025-01-20", "2025-01-21"], "models": [...]}`
-  - New format: `{"start_date": "2025-01-20", "end_date": "2025-01-21"}`
-  - Models parameter is optional (uses enabled models from config)
-  - Config_path parameter removed (server-side detail)
+  - v0.2.0 used sequential batch execution via Docker entrypoint
+  - v0.3.0 introduces REST API for external orchestration
+  - Migration: Use `POST /simulate/trigger` endpoint instead of direct script execution
 - **Data Storage Format Changed** - Price data moved from JSONL to SQLite
-  - Run `python scripts/migrate_price_data.py` to migrate existing data
+  - Run `python scripts/migrate_price_data.py` to migrate existing merged.jsonl data
   - `merged.jsonl` no longer used (replaced by `price_data` table)
   - Automatic on-demand downloads eliminate need for manual data fetching
 - **Configuration Variables Changed**
-  - Added: `AUTO_DOWNLOAD_PRICE_DATA`, `MAX_SIMULATION_DAYS`
-  - Removed: `RUNTIME_ENV_PATH`, MCP port configs, `WEB_HTTP_PORT`
+  - Added: `AUTO_DOWNLOAD_PRICE_DATA`, `MAX_SIMULATION_DAYS`, `API_PORT`
+  - Removed: `RUNTIME_ENV_PATH`, MCP service ports, `WEB_HTTP_PORT`
+  - MCP services now use fixed internal ports (not exposed to host)
 
 ## [0.2.0] - 2025-10-31