Initial implementation of slider

Single-file markdown slideshow for the terminal. Parses slides split by
`---`, renders each with glow, and navigates with n/p/q or arrow keys.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

README.md

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+# slider
+
+Terminal markdown slideshow. Write slides in a single `.md` file, split them with `---`, and navigate with keyboard shortcuts.
+
+## Requirements
+
+- [glow](https://github.com/charmbracelet/glow) v2+
+
+## Usage
+
+```bash
+./bin/slider presentation.md
+```
+
+## Controls
+
+| Key | Action |
+|-----|--------|
+| `n` / right arrow | Next slide |
+| `p` / left arrow | Previous slide |
+| `q` | Quit |
+
+## Writing slides
+
+Separate slides with a `---` on its own line:
+
+```markdown
+# Slide one
+
+Some content here.
+
+---
+
+# Slide two
+
+More content.
+```
+
+See `examples/presentation.md` for a full example.

SPEC.md

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+# Terminal Slide Presentation Tool (slider)
+
+## 🎯 Purpose
+
+Create a standalone terminal-based slide presentation tool using `glow` as the markdown renderer. This tool will allow users to navigate slides via keyboard shortcuts (`n`, `p`, `q`)
+and showcase `glow`'s features like syntax highlighting, tables, and code blocks.
+
+## ✅ Features
+
+- Slide navigation (`n`, `p`, `q`)
+- Markdown rendering using `glow`
+- Support for `glow`-friendly features (code blocks, tables, syntax highlighting)
+- Modular structure for future expansion
+
+## 📁 Project Structure
+
+- `/SPEC.md`: Project specification and roadmap
+- `/examples/`: Test files showcasing `glow` features
+
+## 🚀 Next Steps
+
+1. Implement the navigation script
+2. Add support for slide timing or auto-advance
+3. Integrate with a markdown editor for live preview
+4. Add slide transitions or visual effects
+
+## 📌 Notes
+
+- This project is a lightweight tool for terminal use. For advanced features, consider using `reveal.js` or `remark` in a browser.

bin/slider

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+#!/usr/bin/env bash
+set -euo pipefail
+
+# slider — terminal markdown slideshow
+# Usage: slider <file.md>
+
+usage() {
+    echo "Usage: slider <file.md>" >&2
+    exit 1
+}
+
+[[ $# -ne 1 ]] && usage
+file="$1"
+[[ ! -f "$file" || ! -r "$file" ]] && { echo "Error: cannot read '$file'" >&2; exit 1; }
+
+# Parse slides split on "---"
+slides=()
+current=""
+while IFS= read -r line || [[ -n "$line" ]]; do
+    if [[ "$line" == "---" ]]; then
+        [[ -n "${current// }" ]] && slides+=("$current")
+        current=""
+    else
+        current+="$line"$'\n'
+    fi
+done < "$file"
+[[ -n "${current// }" ]] && slides+=("$current")
+
+total=${#slides[@]}
+[[ $total -eq 0 ]] && { echo "No slides found in '$file'" >&2; exit 1; }
+
+# Temp file for glow rendering; cleaned up on exit
+tmpfile=$(mktemp /tmp/slider.XXXXXX.md)
+trap 'rm -f "$tmpfile"' EXIT
+
+idx=0
+
+show_slide() {
+    tput clear
+    printf "  Slide %d/%d   [n] next  [p] prev  [q] quit\n\n" $((idx + 1)) "$total"
+    printf '%s' "${slides[$idx]}" > "$tmpfile"
+    glow - < "$tmpfile"
+}
+
+show_slide
+
+while true; do
+    read -rsn1 key < /dev/tty
+    case "$key" in
+        n)
+            if (( idx < total - 1 )); then
+                idx=$(( idx + 1 ))
+                show_slide
+            else
+                tput clear
+                printf "  Slide %d/%d   [n] next  [p] prev  [q] quit\n\n" $((idx + 1)) "$total"
+                printf '%s' "${slides[$idx]}" > "$tmpfile"
+                glow - < "$tmpfile"
+                printf "\n  End of presentation — press q to quit\n"
+            fi
+            ;;
+        p)
+            if (( idx > 0 )); then
+                idx=$(( idx - 1 ))
+                show_slide
+            fi
+            ;;
+        $'\x1b')
+            read -rsn2 -t 0.1 rest < /dev/tty || true
+            if [[ "$rest" == "[C" ]]; then  # right arrow → next
+                if (( idx < total - 1 )); then
+                    idx=$(( idx + 1 ))
+                    show_slide
+                else
+                    tput clear
+                    printf "  Slide %d/%d   [n] next  [p] prev  [q] quit\n\n" $((idx + 1)) "$total"
+                    printf '%s' "${slides[$idx]}" > "$tmpfile"
+                    glow - < "$tmpfile"
+                    printf "\n  End of presentation — press q to quit\n"
+                fi
+            elif [[ "$rest" == "[D" ]]; then  # left arrow → prev
+                if (( idx > 0 )); then
+                    idx=$(( idx - 1 ))
+                    show_slide
+                fi
+            fi
+            ;;
+        q)
+            tput clear
+            break
+            ;;
+    esac
+done

examples/presentation.md

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+# Welcome to the Presentation
+
+## Slide 1: Introduction
+
+This is a simple slide to demonstrate `glow`'s capabilities.
+
+### Features Showcase
+
+- **Code Blocks**:
+
+  ```python
+  def greet(name):
+      print(f"Hello, {name}!")
+  ```
+
+- **Tables**:
+
+  | Feature        | Description         |
+  |----------------|---------------------|
+  | Syntax Highlighting | Supports Python, JavaScript, etc. |
+  | Tables          | Easy to read and format |
+  | Markdown        | Full markdown support |
+
+- **Inline Code**:
+  `glow` supports inline code like `print("Hello")`.
+
+---
+
+# Slide 2: Advanced Features
+
+## Code Blocks with Line Numbers
+
+```bash
+#!/bin/bash
+echo "This is a bash script."
+```
+
+## Tables with Markdown
+
+| Column 1 | Column 2 |
+|----------|----------|
+| Data 1   | Data 2   |
+| Data 3   | Data 4   |
+
+## Emoji and Formatting
+
+:smile: This is a smiley!
+**Bold text** and *italic text* are supported.
+
+---
+
+# Slide 3: Conclusion
+
+## Thank You
+
+This is the final slide. Press `q` to exit.