## ADDED Requirements

### Requirement: Active tool mode
The system SHALL maintain an "active tool" state that determines what happens when the user clicks on the chart. Available tool modes are: "select" (default, no action on click), "break_up" (label Break Up), "break_down" (label Break Down), "line" (draw trend line), "rectangle" (draw rectangle annotation), and "delete" (remove annotation). Only one tool SHALL be active at a time.

#### Scenario: Tool activation
- **WHEN** user clicks a tool button in the sidebar
- **THEN** that tool becomes the active tool and the button appears visually selected

#### Scenario: Tool deactivation
- **WHEN** user clicks the already-active tool button
- **THEN** the tool deactivates and the mode returns to "select"

### Requirement: Break Up labeling
When the "break_up" tool is active and the user clicks on the chart, the system SHALL identify the nearest candle to the click coordinates using `chart.timeScale().coordinateToTime()`. The system SHALL save an annotation with `label_type: "break_up"` and the candle's timestamp to the database. A green upward arrow marker SHALL appear on the chart immediately.

#### Scenario: Place Break Up label
- **WHEN** "break_up" tool is active and user clicks on a candle
- **THEN** system saves a "break_up" annotation for that candle's timestamp and displays a green arrow marker above the bar

#### Scenario: Click between candles
- **WHEN** "break_up" tool is active and user clicks between two candles
- **THEN** system snaps to the nearest candle timestamp and places the annotation there

### Requirement: Break Down labeling
When the "break_down" tool is active and the user clicks on the chart, the system SHALL behave identically to Break Up labeling but save `label_type: "break_down"` and display a red downward arrow below the bar.

#### Scenario: Place Break Down label
- **WHEN** "break_down" tool is active and user clicks on a candle
- **THEN** system saves a "break_down" annotation for that candle's timestamp and displays a red arrow marker below the bar

### Requirement: Two-click line drawing
When the "line" tool is active, the system SHALL implement a two-click drawing interaction using `chart.subscribeClick()` for click detection and `chart.subscribeCrosshairMove()` for preview updates. The first click sets the start point (time, price). The second click sets the end point (time, price). After the second click, the system SHALL save an annotation with `label_type: "line"` and `geometry` containing JSON: `{"startTime": <unix>, "startPrice": <float>, "endTime": <unix>, "endPrice": <float>}`. The line SHALL render immediately as a TrendLine primitive attached to the candlestick series.

#### Scenario: Draw a trend line
- **WHEN** "line" tool is active and user clicks two points on the chart
- **THEN** system saves a line annotation with start/end coordinates and renders the line as a TrendLine primitive

#### Scenario: Visual feedback during line drawing
- **WHEN** "line" tool is active and user has clicked the first point but not the second
- **THEN** system displays a preview TrendLine primitive (dashed or semi-transparent) from the first point to the current crosshair position, updating via `subscribeCrosshairMove()`

#### Scenario: Cancel line drawing
- **WHEN** user presses Escape during a two-click line drawing (after first click)
- **THEN** system cancels the line drawing, detaches the preview primitive, and clears the drawing state without saving

### Requirement: Line rendering via TrendLine plugin
The system SHALL render saved line annotations using the `TrendLine` class (implementing `ISeriesPrimitive<Time>`) instead of SVG `<line>` elements. Each line annotation SHALL have one `TrendLine` primitive instance attached to the candlestick series via `series.attachPrimitive()`. The `SvgOverlay` component SHALL be removed.

#### Scenario: Saved lines render as canvas primitives
- **WHEN** line annotations exist for the active chart
- **THEN** each line renders via a TrendLine primitive on the chart canvas (not SVG overlay)

#### Scenario: Lines participate in autoscaling
- **WHEN** a line annotation's price range extends beyond visible candle data
- **THEN** the chart autoscale includes the line's price range via `autoscaleInfo()`

#### Scenario: Lines update on zoom/pan
- **WHEN** user zooms or pans the chart
- **THEN** line primitives automatically reposition via the ISeriesPrimitive lifecycle

### Requirement: Line hit testing
The `TrendLine` class SHALL implement `hitTest(x, y)` to detect clicks near the line. Hit testing SHALL calculate the perpendicular distance from the click point to the line segment and return a hit if within 10 CSS pixels (scaled by device pixel ratio).

#### Scenario: Click near line detected
- **WHEN** user clicks within 10 CSS pixels of a line segment
- **THEN** `hitTest()` returns a `PrimitiveHoveredItem` with the annotation ID as `externalId`

#### Scenario: Click far from line not detected
- **WHEN** user clicks more than 10 CSS pixels from any line segment
- **THEN** `hitTest()` returns null

### Requirement: Line selection handles via plugin
When a line is selected, the `TrendLine` renderer SHALL draw circular endpoint handles (radius 6px) at both endpoints of the line. The handles SHALL be rendered as part of the canvas draw call, not as separate SVG elements.

#### Scenario: Handles appear on selection
- **WHEN** a line is selected (via click with line tool active)
- **THEN** circular handles render at both endpoints of the line on the canvas

#### Scenario: Handles disappear on deselection
- **WHEN** the selected line is deselected (Escape key or clicking elsewhere)
- **THEN** the endpoint handles no longer render

### Requirement: Delete annotation
When the "delete" tool is active and the user clicks on or near an existing annotation (marker, line, or rectangle), the system SHALL remove that annotation from the database and update the chart display immediately. Line and rectangle hit detection SHALL use the primitive's `hitTest()` method instead of SVG proximity calculation.

#### Scenario: Delete a marker annotation
- **WHEN** "delete" tool is active and user clicks on a candle that has a marker annotation
- **THEN** system removes the annotation from the database and the marker disappears from the chart

#### Scenario: Delete a line annotation
- **WHEN** "delete" tool is active and user clicks near an existing line
- **THEN** system detects the hit via `TrendLine.hitTest()`, sends DELETE /api/annotations/{id}, detaches the primitive from the series, and updates the annotation list

#### Scenario: Delete a rectangle annotation
- **WHEN** "delete" tool is active and user clicks within a rectangle
- **THEN** system detects the hit via `RectangleDrawingPrimitive.hitTest()`, sends DELETE /api/annotations/{id}, detaches the primitive, and updates the annotation list

### Requirement: Coordinate mapping
The system SHALL convert mouse click pixel coordinates to chart data coordinates (time and price) using the lightweight-charts API: `chart.timeScale().coordinateToTime(x)` for time and `series.coordinateToPrice(y)` for price. For point annotations, the time SHALL be snapped to the nearest candle timestamp.

#### Scenario: Pixel to data coordinate conversion
- **WHEN** user clicks at pixel position (x, y) on the chart
- **THEN** system correctly converts to the corresponding time and price values using the chart API

### Requirement: Annotations database table
The system SHALL store annotations in an `annotations` table with columns: `id` (integer primary key, auto-increment), `timestamp` (integer, Unix timestamp referencing a candle time), `label_type` (text: "break_up", "break_down", or "line"), `geometry` (text, nullable, JSON string for line coordinates), `created_at` (integer, Unix timestamp of creation).

#### Scenario: Schema structure
- **WHEN** the database is initialized
- **THEN** the `annotations` table exists with all required columns
