## MODIFIED Requirements

### Requirement: Upload endpoint
The system SHALL provide a `POST /api/upload` endpoint that accepts a CSV file via multipart form data. The endpoint SHALL create a new chart (named from the uploaded filename without extension), parse the CSV using papaparse, validate the format, and insert all candle records into the `candles` table with the new chart's `chart_id` within a single database transaction. On success, the endpoint SHALL return a JSON response with the chart `id`, chart `name`, and the count of inserted records. On failure, it SHALL return an appropriate error status and message without creating a chart.

#### Scenario: Successful upload
- **WHEN** a valid CSV file named "BTC-1H.csv" is sent to POST /api/upload
- **THEN** endpoint creates a chart named "BTC-1H", inserts candles with that chart_id, and returns `{ "success": true, "count": <number>, "chart": { "id": <number>, "name": "BTC-1H" } }` with HTTP 200

#### Scenario: Invalid CSV upload
- **WHEN** a CSV with missing or invalid headers is sent to POST /api/upload
- **THEN** endpoint returns `{ "error": "<description>" }` with HTTP 400 and does not create a chart

#### Scenario: No file provided
- **WHEN** POST /api/upload is called without a file
- **THEN** endpoint returns `{ "error": "No file provided" }` with HTTP 400

#### Scenario: Duplicate filename
- **WHEN** a CSV named "BTC-1H.csv" is uploaded and a chart named "BTC-1H" already exists
- **THEN** endpoint creates a chart named "BTC-1H-2" (or next available suffix) and inserts candles under that chart

### Requirement: Get annotations endpoint
The system SHALL provide a `GET /api/annotations` endpoint that accepts an optional `chartId` query parameter. When `chartId` is provided, the endpoint SHALL return only annotations belonging to that chart. When `chartId` is omitted, the endpoint SHALL return annotations for the most recently created chart. Each annotation object SHALL include: `id`, `chart_id`, `timestamp`, `label_type`, `geometry` (parsed from JSON string or null), and `created_at`.

#### Scenario: Fetch annotations for specific chart
- **WHEN** GET /api/annotations?chartId=3 is called
- **THEN** endpoint returns a JSON array of annotations where chart_id equals 3, with HTTP 200

#### Scenario: Fetch annotations without chartId
- **WHEN** GET /api/annotations is called without a chartId parameter
- **THEN** endpoint returns annotations for the most recently created chart with HTTP 200

#### Scenario: No annotations exist for chart
- **WHEN** GET /api/annotations?chartId=3 is called and no annotations exist for chart 3
- **THEN** endpoint returns an empty JSON array `[]` with HTTP 200

### Requirement: Create annotation endpoint
The system SHALL provide a `POST /api/annotations` endpoint that accepts a JSON body with fields: `timestamp` (required, integer), `label_type` (required, string), `chart_id` (required, integer), and `geometry` (optional, object). The endpoint SHALL validate the input, verify the chart exists, serialize geometry to JSON string if present, and insert the record into the `annotations` table. On success, it SHALL return the created annotation object with its assigned `id`.

#### Scenario: Create a marker annotation
- **WHEN** POST /api/annotations is called with `{ "timestamp": 1700000000, "label_type": "break_up", "chart_id": 3 }`
- **THEN** endpoint saves the annotation with chart_id 3 and returns the created object with `id` and HTTP 201

#### Scenario: Create a line annotation
- **WHEN** POST /api/annotations is called with `{ "timestamp": 1700000000, "label_type": "line", "chart_id": 3, "geometry": { "startTime": 1700000000, "startPrice": 1.05, "endTime": 1700100000, "endPrice": 1.06 } }`
- **THEN** endpoint saves the annotation with chart_id 3 and serialized geometry JSON, returns the created object with HTTP 201

#### Scenario: Invalid annotation data
- **WHEN** POST /api/annotations is called with missing required fields (timestamp, label_type, or chart_id)
- **THEN** endpoint returns `{ "error": "<description>" }` with HTTP 400

#### Scenario: Annotation for non-existent chart
- **WHEN** POST /api/annotations is called with a chart_id that does not exist
- **THEN** endpoint returns `{ "error": "Chart not found" }` with HTTP 404

### Requirement: Get candles endpoint
The system SHALL provide a `GET /api/candles` endpoint that accepts an optional `chartId` query parameter. When `chartId` is provided, the endpoint SHALL return only candles belonging to that chart. When `chartId` is omitted, the endpoint SHALL return candles for the most recently created chart. Results SHALL be ordered by time ascending. Each object SHALL include: `time`, `open`, `high`, `low`, `close`.

#### Scenario: Fetch candles for specific chart
- **WHEN** GET /api/candles?chartId=3 is called
- **THEN** endpoint returns a JSON array of candle objects where chart_id equals 3, ordered by time ascending with HTTP 200

#### Scenario: Fetch candles without chartId
- **WHEN** GET /api/candles is called without a chartId parameter
- **THEN** endpoint returns candles for the most recently created chart with HTTP 200

#### Scenario: No candles exist for chart
- **WHEN** GET /api/candles?chartId=3 is called and no candles exist for chart 3
- **THEN** endpoint returns an empty JSON array `[]` with HTTP 200

### Requirement: Export annotations endpoint
The system SHALL provide a `GET /api/export` endpoint that accepts an optional `chartId` query parameter. When `chartId` is provided, the endpoint SHALL export only annotations for that chart. When `chartId` is omitted, the endpoint SHALL export annotations for the most recently created chart. The CSV SHALL have columns: `timestamp`, `label_type`, `price`. The response SHALL set `Content-Type: text/csv` and `Content-Disposition: attachment; filename="annotations.csv"` headers.

#### Scenario: Export for specific chart
- **WHEN** GET /api/export?chartId=3 is called and annotations exist for chart 3
- **THEN** endpoint returns a CSV file download with only annotations belonging to chart 3

#### Scenario: Export without chartId
- **WHEN** GET /api/export is called without a chartId parameter
- **THEN** endpoint exports annotations for the most recently created chart
