spec: add ohlc-bar specification (#3296)

## New Specification: `ohlc-bar`

Related to #3293

---

### specification.md

# ohlc-bar: OHLC Bar Chart

## Description

An OHLC (Open-High-Low-Close) bar chart displays financial price data
using vertical bars with horizontal tick marks. Each bar shows the price
range from high to low as a thin vertical line, with a left tick
indicating the opening price and a right tick indicating the closing
price. Unlike candlestick charts that use colored bodies, OHLC bars
provide a cleaner, less cluttered view favored by technical analysts who
prefer to focus on price levels rather than visual patterns.

## Applications

- Analyzing daily stock price movements with focus on precise price
levels
- Comparing price action across multiple securities on the same chart
without color distraction
- Technical analysis where traders prefer bar charts over candlesticks
for pattern recognition

## Data

- `date` (datetime) - The time period for each bar (e.g., day, hour,
minute)
- `open` (numeric) - Opening price at the start of the period
- `high` (numeric) - Highest price during the period
- `low` (numeric) - Lowest price during the period
- `close` (numeric) - Closing price at the end of the period
- Size: 20-100 periods for clear visualization
- Example: Daily OHLC prices for a stock over 30-60 trading days

## Notes

- Use thin vertical lines for the high-low range
- Horizontal ticks should extend to the left for open and right for
close
- Consider using different colors for up bars (close > open) vs down
bars (close < open) for easier reading
- Time axis should have appropriate date formatting based on data
frequency
- Grid lines help read exact price levels

---

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---
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plots/ohlc-bar/specification.md

@@ -0,0 +1,29 @@
+# ohlc-bar: OHLC Bar Chart
+
+## Description
+
+An OHLC (Open-High-Low-Close) bar chart displays financial price data using vertical bars with horizontal tick marks. Each bar shows the price range from high to low as a thin vertical line, with a left tick indicating the opening price and a right tick indicating the closing price. Unlike candlestick charts that use colored bodies, OHLC bars provide a cleaner, less cluttered view favored by technical analysts who prefer to focus on price levels rather than visual patterns.
+
+## Applications
+
+- Analyzing daily stock price movements with focus on precise price levels
+- Comparing price action across multiple securities on the same chart without color distraction
+- Technical analysis where traders prefer bar charts over candlesticks for pattern recognition
+
+## Data
+
+- `date` (datetime) - The time period for each bar (e.g., day, hour, minute)
+- `open` (numeric) - Opening price at the start of the period
+- `high` (numeric) - Highest price during the period
+- `low` (numeric) - Lowest price during the period
+- `close` (numeric) - Closing price at the end of the period
+- Size: 20-100 periods for clear visualization
+- Example: Daily OHLC prices for a stock over 30-60 trading days
+
+## Notes
+
+- Use thin vertical lines for the high-low range
+- Horizontal ticks should extend to the left for open and right for close
+- Consider using different colors for up bars (close > open) vs down bars (close < open) for easier reading
+- Time axis should have appropriate date formatting based on data frequency
+- Grid lines help read exact price levels

plots/ohlc-bar/specification.yaml

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+# Specification-level metadata for ohlc-bar
+# Auto-synced to PostgreSQL on push to main
+
+spec_id: ohlc-bar
+title: OHLC Bar Chart
+
+# Specification tracking
+created: 2026-01-08T15:54:27Z
+updated: null
+issue: 3293
+suggested: MarkusNeusinger
+
+# Classification tags (applies to all library implementations)
+# See docs/reference/tagging-system.md for detailed guidelines
+tags:
+  plot_type:
+    - ohlc
+    - bar
+  data_type:
+    - timeseries
+    - numeric
+  domain:
+    - finance
+  features:
+    - basic
+    - temporal