## MODIFIED Requirements

### Requirement: CSV file upload
The system SHALL provide a file upload component that accepts CSV files containing OHLC candle data. The CSV format MUST have columns: `time`, `open`, `high`, `low`, `close`. The `time` column SHALL accept both `YYYY-MM-DD` date strings and Unix timestamps (integer seconds). Uploading a CSV SHALL create a new chart (named from the filename without extension) and insert all candle rows associated with that chart, rather than replacing existing data.

#### Scenario: Valid CSV upload
- **WHEN** user uploads a CSV file with valid headers (time, open, high, low, close) and valid data rows
- **THEN** system creates a new chart named from the filename (without .csv extension), parses all rows, and stores them in the `candles` table with the new chart's `chart_id`

#### Scenario: CSV with Unix timestamps
- **WHEN** user uploads a CSV where the `time` column contains Unix timestamps (e.g., 1700000000)
- **THEN** system stores the timestamps as integers in the database with the correct `chart_id` and renders candles correctly on the chart

#### Scenario: CSV with date strings
- **WHEN** user uploads a CSV where the `time` column contains date strings (e.g., "2024-01-15")
- **THEN** system converts dates to Unix timestamps and stores them in the database with the correct `chart_id`

#### Scenario: Invalid CSV format
- **WHEN** user uploads a CSV missing required headers or containing malformed data
- **THEN** system displays an error message describing the issue, does not create a chart, and does not store any partial data

#### Scenario: Duplicate filename upload
- **WHEN** user uploads a CSV whose filename (without extension) matches an existing chart name
- **THEN** system appends a numeric suffix to the chart name (e.g., "btc-daily-2") and creates a new chart with the suffixed name

### Requirement: Candles database table
The system SHALL store candle data in a `candles` table with columns: `id` (integer primary key, auto-increment), `chart_id` (integer, foreign key to `charts.id`, NOT NULL), `time` (integer, Unix timestamp), `open` (real), `high` (real), `low` (real), `close` (real). The table MUST have a composite unique constraint on `(chart_id, time)`.

#### Scenario: Schema structure
- **WHEN** the database is initialized
- **THEN** the `candles` table exists with all required columns including `chart_id` and the composite unique constraint on `(chart_id, time)`

#### Scenario: Same timestamp across different charts
- **WHEN** two different charts have candles with the same Unix timestamp
- **THEN** both records are stored successfully because the unique constraint is per-chart