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_docs/02_document/modules/ai_availability_status.md

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+# Module: ai_availability_status
+
+## Purpose
+
+Thread-safe status tracker for the AI engine lifecycle (downloading, converting, uploading, enabled, warning, error).
+
+## Public Interface
+
+### Enum: AIAvailabilityEnum
+
+| Value | Name | Meaning |
+|-------|------|---------|
+| 0 | NONE | Initial state, not yet initialized |
+| 10 | DOWNLOADING | Model download in progress |
+| 20 | CONVERTING | ONNX-to-TensorRT conversion in progress |
+| 30 | UPLOADING | Converted model upload in progress |
+| 200 | ENABLED | Engine ready for inference |
+| 300 | WARNING | Operational with warnings |
+| 500 | ERROR | Failed, not operational |
+
+### Class: AIAvailabilityStatus
+
+| Field | Type | Description |
+|-------|------|-------------|
+| `status` | AIAvailabilityEnum | Current status |
+| `error_message` | str or None | Error/warning details |
+
+| Method | Signature | Description |
+|--------|-----------|-------------|
+| `__init__` | `()` | Sets status=NONE, error_message=None |
+| `__str__` | `() -> str` | Thread-safe formatted string: `"StatusText ErrorText"` |
+| `serialize` | `() -> bytes` | Thread-safe msgpack serialization `{s: status, m: error_message}` **(legacy — not called in current codebase)** |
+| `set_status` | `(AIAvailabilityEnum status, str error_message=None) -> void` | Thread-safe status update; logs via constants_inf (error or info) |
+
+## Internal Logic
+
+All public methods acquire a `threading.Lock` before reading/writing status fields. `set_status` logs the transition: errors go to `constants_inf.logerror`, normal transitions go to `constants_inf.log`.
+
+## Dependencies
+
+- **External**: `msgpack`, `threading`
+- **Internal**: `constants_inf` (logging)
+
+## Consumers
+
+- `inference` — creates instance, calls `set_status` during engine lifecycle, exposes `ai_availability_status` for health checks
+- `main` — reads `ai_availability_status` via inference for `/health` endpoint
+
+## Data Models
+
+- `AIAvailabilityEnum` — status enum
+- `AIAvailabilityStatus` — stateful status holder
+
+## Configuration
+
+None.
+
+## External Integrations
+
+None.
+
+## Security
+
+Thread-safe via Lock — safe for concurrent access from FastAPI async + ThreadPoolExecutor.
+
+## Tests
+
+None found.