# Handoff Report: Character Stat Aggregator & Server Engine Integration

- **Agent**: `worker_core_1` (teamwork_preview_worker / Lead Backend & Systems Engineer)
- **Role**: implementer, qa, specialist
- **Task**: Character Stat Aggregator, SQLite Formula Persistence, and Server Engine Loop Integration
- **Date**: 2026-10-04
- **Working Directory**: `c:\Projects\FreeExile\.agents\teamwork\worker_core_1`

---

## 1. Observation

### 1.1 Codebase State Prior to Changes
- `server/world/server_engine_loop.py` lines 105-113: Player registration hardcoded `CombatActor(base_attack=50.0, max_hp=1000.0, crit_chance=0.05, crit_multiplier=1.5, move_speed=6.0)`, ignoring all equipment affixes and Meridian passives.
- No unified stat aggregator existed combining base character attributes, equipment affixes (`inventory_service.py`), and passive constellations (`meridian_service.py`).
- No database table or service existed for serializing calculation ASTs for zero-trust auditing.

### 1.2 Implemented Changes & Line Limits Compliance
All files adhere to the exclusive write boundaries and strict line caps:
1. `server/stats/stat_types.py` (187 lines, cap < 200 lines):
   - `ModifierType` enum (`FLAT`, `INCREASED`, `REDUCED`, `MORE`, `LESS`).
   - `StatModifier` dataclass (`stat_key`, `mod_type`, `value`, `tags`, `condition`, `source`).
   - `ASTNode` hierarchy (`ConstantNode`, `SumNode`, `ScaleFactorNode`, `ProductNode`, `ModifierContributionNode`) with `.to_dict()`.
   - `EvaluationContext` dataclass (`active_tags`, `conditions`, `current_hp_ratio`).
   - `AggregatedCharacterStats` dataclass (`attack_damage`, `max_hp`, `crit_chance`, `crit_multiplier`, `move_speed`, `resistances`, `all_stats`) with `.base_attack` and `.movement_speed` aliases.
2. `server/stats/formula_persistence.py` (163 lines, cap < 250 lines):
   - `FormulaPersistenceService` managing SQLite table `character_stat_calculations` in `data/character_stat_formulas.db` (supports `:memory:`).
   - WAL mode, `PRAGMA synchronous = NORMAL`, `foreign_keys = ON`, `row_factory = sqlite3.Row`.
   - Methods: `save_calculation`, `get_calculation`, `get_player_calculations`, `close`.
3. `server/stats/stat_aggregator.py` (329 lines, cap < 350 lines):
   - `CharacterStatAggregator` combining base attributes (50 STR/DEX/INT), item affixes (both `Affix` and `AffixMod`, 2H +50% More damage, DW +10% APS & +15% block), and Meridian passives (`compute_total_stats`).
   - Pure Path of Exile formula:
     $$\text{FinalStat} = (\text{Base} + \sum \text{Flat}) \times (1.0 + \frac{\sum \text{Inc} - \sum \text{Red}}{100.0}) \times \prod (1.0 + \text{More}) \times \prod (1.0 - \text{Less})$$
   - Tag-based filtering and conditional modifiers (`on_low_health` when HP <= 35%).
   - Generates AST tree and persists to SQLite.
4. `server/stats/__init__.py` (35 lines):
   - Package exports for all types, persistence, and aggregator classes.
5. `server/world/server_engine_loop.py` (292 lines, cap < 350 lines):
   - Pre-flight unlocked via `python tools/analysis/blast_radius.py --target server/world/server_engine_loop.py --ack`.
   - `ServerEngineLoop.__init__` accepts `stat_aggregator: Optional[Any] = None`.
   - `register_player` accepts `aggregated_stats`, `player_id`, `account_id`, `character_id`, `context_tags`, `conditions`, `context`.
   - When provided, initializes `CombatActor` with `base_attack`, `max_hp`, `crit_chance`, `crit_multiplier`, `resistances` (mapped to `FiveElements`), `is_player=True`, and synchronizes `PlayerCharacter.move_speed`.
   - When omitted, falls back to default `50.0 / 1000.0 / 6.0` values, guaranteeing 100% backward compatibility.
6. `tests/unit/test_character_stat_aggregator.py` (221 lines, cap < 350 lines):
   - 12 comprehensive unit tests covering math, tags, conditions, mock player, 2H/DW grips, AST serialization, SQLite persistence, and engine loop integration.

### 1.3 Verbatim Command Execution Outputs
- **Unit Test Execution**:
  ```
  pytest tests/unit/test_character_stat_aggregator.py
  ...
  ============================= 12 passed in 0.33s ==============================
  ```
- **Regression & Dependents Test Execution**:
  ```
  pytest tests/unit/test_character_stat_aggregator.py tests/unit/test_isometric_engine_loop.py tests/unit/test_combat_engine.py tests/unit/test_inventory_service.py tests/unit/test_meridian_server_service.py tests/unit/test_agent_decision_core.py tests/unit/test_agent_orb_service.py tests/unit/test_agent_orb_hmac.py
  ...
  ======================= 45 passed, 2 warnings in 1.56s ========================
  ```
- **Hygiene Audit**:
  ```
  python tools/lint/check_code_and_doc_hygiene.py --strict
  ...
  ================================================================================
  ✅ KẾT QUẢ: TOÀN BỘ MÃ NGUỒN VÀ TÀI LIỆU TUÂN THỦ HARD CAP HYGIENE!
  ================================================================================
  ```

---

## 2. Logic Chain

1. **Requirement Mapping**:
   - The user requested a `CharacterStatAggregator` combining equipped items, Meridian passives, and base attributes under PoE math (Flat, Inc/Red, More/Less, tags, conditions), with AST persistence to SQLite and engine loop integration.
   - Observation 1.1 showed that `ServerEngineLoop.register_player` was using hardcoded 50.0 attack damage and 1000.0 HP.
2. **Architecture & Decoupling**:
   - To adhere to `PROJECT.md` and line limits, the solution was partitioned into `stat_types.py` (models & AST), `formula_persistence.py` (SQLite layer), and `stat_aggregator.py` (mathematical business logic).
   - This kept each file under its designated line cap (187, 163, and 329 lines respectively).
3. **Safety & Blast Radius Compliance**:
   - `server/world/server_engine_loop.py` was marked as CRITICAL risk with 7 dependents.
   - We executed `python tools/analysis/blast_radius.py --target server/world/server_engine_loop.py --ack` prior to editing.
   - In `register_player`, optional parameters and fallbacks were designed such that calls omitting `aggregated_stats` behave identically to legacy behavior.
4. **Verification Evidence**:
   - Testing `test_character_stat_aggregator.py` confirms that 2H weapons yield +50% More damage, dual wielding yields +10% More APS and +15% block, tag filtering filters out non-matching elements, conditional triggers activate at low life, AST serializes to valid JSON, and SQLite records persist.
   - Testing existing test suites (`test_isometric_engine_loop.py`, `test_combat_engine.py`, `test_inventory_service.py`, `test_meridian_server_service.py`, `test_agent_decision_core.py`, etc.) proves zero regressions across all 45 test cases.

---

## 3. Caveats

- The scope of this task is strictly server-authoritative calculation, persistence, and engine loop initialization. Client-side UI display of character sheet panels is handled by separate client modules.
- In `FormulaPersistenceService`, table schema uses WAL mode when operating on disk. For unit tests, `:memory:` database maintains an active connection throughout the test lifecycle.

---

## 4. Conclusion

The Character Stat Aggregator system is fully implemented, verified, and integrated into FreeExile. All acceptance criteria from `ORIGINAL_REQUEST.md` (Header `## 2026-10-04T09:01:16Z`), `DISPATCH.md`, and `PROJECT.md` have been met with 100% test pass rate and zero hygiene violations.

---

## 5. Verification Method

To independently verify the implementation, execute the following commands from the repository root (`c:\Projects\FreeExile`):

1. **Run Aggregator Unit Tests**:
   ```bash
   pytest tests/unit/test_character_stat_aggregator.py -v
   ```
   *Expected Output*: 12 passed.

2. **Run Combined Engine & Dependents Suite**:
   ```bash
   pytest tests/unit/test_character_stat_aggregator.py tests/unit/test_isometric_engine_loop.py tests/unit/test_combat_engine.py tests/unit/test_inventory_service.py tests/unit/test_meridian_server_service.py
   ```
   *Expected Output*: 33 passed.

3. **Run Hygiene & Line Limits Audit**:
   ```bash
   python tools/lint/check_code_and_doc_hygiene.py --strict
   ```
   *Expected Output*: Exit code 0, 100% Hard Cap compliance.

4. **Inspect Formula AST in SQLite**:
   ```bash
   python -c "from server.stats.formula_persistence import FormulaPersistenceService; s = FormulaPersistenceService(':memory:'); s.save_calculation('test_p', 'calc_1', {'atk': {'val': 150.0}}, {'attack_damage': 150.0}); print(s.get_calculation('calc_1')['final_stats'])"
   ```
   *Expected Output*: `{'attack_damage': 150.0}`

*Invalidation Conditions*: Any failure in the above test commands, or any line count exceeding the soft/hard limits.