candle-annotator/openspec/specs/chart-canvas/spec.md

ADDED Requirements

Requirement: Candlestick chart rendering

The system SHALL render candle data as a candlestick chart using the lightweight-charts library (v4). The chart MUST display OHLC data with candlestick visuals using a black and white color scheme. Bullish candles SHALL have a white interior with black outline and black wicks. Bearish candles SHALL be completely black (black fill and black wicks). The chart SHALL be a client-side React component. The chart SHALL fetch and display candles scoped to the active chart by passing chartId to the GET /api/candles endpoint.

Scenario: Chart renders candle data for active chart

• WHEN an active chart is selected and candle data exists for that chart
• THEN the chart fetches candles via GET /api/candles?chartId=<activeChartId> and renders only that chart's candles

Scenario: Empty state

• WHEN no charts exist or the active chart has no candle data
• THEN the chart area displays an empty chart with a prompt to upload CSV data

Scenario: Bullish candle appearance

• WHEN a candle's close price is higher than its open price (bullish)
• THEN the candle displays with white interior, black border, and black wick

Scenario: Bearish candle appearance

• WHEN a candle's close price is lower than its open price (bearish)
• THEN the candle displays as completely black (black fill and black wick)

Scenario: Chart switches when active chart changes

• WHEN user selects a different chart from the chart selector
• THEN the chart clears existing data, fetches candles for the newly selected chart, and renders the new dataset

Requirement: Chart interactivity

The chart SHALL support zooming (mouse wheel), panning (click and drag on time axis), and crosshair display (showing price/time on hover). These are built-in lightweight-charts behaviors that MUST be enabled.

Scenario: Zoom and pan

• WHEN user scrolls the mouse wheel over the chart
• THEN the chart zooms in or out on the time axis

Scenario: Crosshair display

• WHEN user hovers the mouse over the chart
• THEN a crosshair displays with the current price and time at the cursor position

Requirement: Responsive chart layout

The chart MUST fill the available width of the main content area (excluding the sidebar). The chart height SHALL be responsive, using the full viewport height minus header/toolbar areas. The chart MUST resize when the browser window is resized.

Scenario: Window resize

• WHEN user resizes the browser window
• THEN the chart resizes to fill the available space without requiring a page reload

Requirement: Dark theme chart

The chart SHALL use a dark color scheme consistent with the application's Slate-900 dark theme. Background MUST be dark, grid lines subtle, and text/crosshair in light colors.

Scenario: Dark theme applied

• WHEN the chart renders
• THEN the chart background, grid, text, and crosshair colors match the dark theme (dark background, light text)

Requirement: Annotation markers on chart

The chart SHALL display visual markers for existing annotations using the series.setMarkers() API. Break Up annotations MUST appear as green upward arrows above the bar. Break Down annotations MUST appear as red downward arrows below the bar. Markers MUST update when annotations are added or deleted. Markers SHALL be scoped to the active chart by fetching annotations via GET /api/annotations?chartId=<activeChartId>.

Scenario: Break Up marker display

• WHEN a Break Up annotation exists for a candle timestamp in the active chart
• THEN a green upward arrow marker appears above that candle on the chart

Scenario: Break Down marker display

• WHEN a Break Down annotation exists for a candle timestamp in the active chart
• THEN a red downward arrow marker appears below that candle on the chart

Scenario: Marker updates on annotation change

• WHEN user adds or deletes an annotation on the active chart
• THEN chart markers update immediately without requiring a page reload

Scenario: Markers refresh on chart switch

• WHEN user switches to a different chart
• THEN markers from the previous chart are cleared and markers for the new chart's annotations are loaded

Requirement: Refs for event handler closure values

The CandleChart component SHALL use useRef for state values that are read inside event handlers (drawingState, selectedLineId, dragState, annotations). The ref SHALL be updated alongside every setState call. Event handlers SHALL read from the ref instead of the closure variable.

Scenario: Click handler reads current state

• WHEN the user clicks on the chart after state has changed
• THEN the click handler reads the current value from the ref (not a stale closure value)

Scenario: Reduced re-subscription frequency

• WHEN refs are used for mutable state in event handlers
• THEN the useEffect dependency array for chart event subscriptions is smaller, reducing re-subscription frequency

Requirement: Theme change without chart re-creation

The CandleChart component SHALL apply theme changes using chart.applyOptions() instead of destroying and re-creating the entire chart instance. This preserves scroll position, zoom level, and attached primitives.

Scenario: Theme toggle preserves state

• WHEN the user toggles between light and dark theme
• THEN the chart colors update without losing scroll position, zoom level, or annotation primitives

Requirement: Dynamic candle interval detection

The CandleChart component SHALL determine the actual candle interval from the data (by examining the time difference between consecutive candles) instead of hardcoding 60 seconds. The detected interval SHALL be used for span annotation iteration loops.

Scenario: 1-minute candles

• WHEN candle data has 60-second intervals
• THEN the span iteration step is 60 seconds

Scenario: 1-hour candles

• WHEN candle data has 3600-second intervals
• THEN the span iteration step is 3600 seconds (not 60)

Scenario: No performance degradation on high timeframes

• WHEN iterating over a span on daily candles
• THEN the loop iterates over actual candle count (not 1440x more iterations)

Requirement: Named constants for magic numbers

The CandleChart component SHALL extract hardcoded magic numbers (8px padding, 60s interval, color values) into named constants at the module level.

Scenario: Constants used instead of magic numbers

• WHEN the CandleChart source is inspected
• THEN magic numbers like 8, 60, hardcoded colors are replaced with descriptive constant names

Requirement: Module-level empty Set default

The new Set<string>() default prop value SHALL be defined as a module-level constant instead of being recreated on every render.

Scenario: Stable default reference

• WHEN CandleChart renders without hiddenLabels prop
• THEN it uses a module-level EMPTY_SET constant (same reference across renders)