## ADDED Requirements

### Requirement: Training resource limits
The `POST /training/start` endpoint SHALL enforce resource limits: the training dataset file size SHALL not exceed 500MB, and the training thread SHALL have a configurable timeout (default: 30 minutes). If the timeout is exceeded, the training thread SHALL be marked as failed.

#### Scenario: Dataset too large
- **WHEN** the training dataset exceeds 500MB
- **THEN** training fails immediately with `{ "detail": "Dataset too large. Maximum 500MB." }`

#### Scenario: Training timeout
- **WHEN** a training run exceeds the 30-minute timeout
- **THEN** the training status is set to "failed" with reason "Training timed out"

### Requirement: run_id validation on training endpoints
The FastAPI training endpoints (`DELETE /training/runs/{run_id}`, `GET /training/runs/{run_id}`) SHALL validate that `run_id` matches `/^[a-zA-Z0-9_-]+$/` before any database or file operation.

#### Scenario: Valid run_id
- **WHEN** `DELETE /training/runs/run-2024-01-15_v3` is called
- **THEN** the request proceeds normally

#### Scenario: Invalid run_id
- **WHEN** `DELETE /training/runs/../../admin` is called
- **THEN** the endpoint returns HTTP 400 with `{ "detail": "Invalid run_id format" }`
