Dead Code Heatmap — Visualize code freshness using Git history

[NK2552003]

Static dead code detectors only flag unused exports. They don't show how recently code was touched or whether it's actively maintained. A visual freshness heatmap helps devs prioritize refactoring and cleanup.

Objective

Create line-level editor decorations that color-code code based on last modification date via git blame/git log.

Scope & Implementation Details

1. Git Integration

• Execute: git log --format="%H %ai" -- <file>
• Parse timestamps per line using git blame --line-porcelain or diff-based mapping
• Cache results per file path + HEAD commit hash

2. Heat Mapping Logic

• Calculate age per line: now - lastModified
• Color thresholds:
  • $(green) < 7 days → #4caf50
  • $(yellow) 7–30 days → #ff9800
  • $(red) > 30 days → #f44336
• Gracefully fallback to gray for untracked files

3. Editor Decorations

• Use vscode.window.createTextEditorDecorationType
• Apply line ranges via setDecorations
• Tooltip on hover: "Last modified: 42 days ago by @user"

4. Performance Safeguards

• Skip files > 10,000 lines or outside workspace
• Debounce decoration updates on save/scroll
• Cache git output in workspaceState or memory map

Acceptance Criteria

• Fetches accurate last-modified dates per line
• Applies correct color thresholds
• Hover tooltips show age + author (if available)
• No editor lag on files ≤5k lines
• Disables cleanly in non-git repositories

Technical Notes

• Use child_process.exec with maxBuffer: 10 * 1024 * 1024
• Run git commands off the main thread or via execAsync
• Invalidate cache on workspace.onDidChangeTextDocument + save
• Consider git log -L for range-specific history if blame is slow

(use codicons not emojis)

[NK2552003]

Enhances that are going to be implemented are :-

• Animated heat pulse - Lines that were very recently modified (< 1 hour) pulse/fade animation
• Commit heat density visualization - A minimap-style sidebar showing the "heat distribution" of the entire file
• Author blame rings - Color-code by author as well as age, with configurable author colors
• Refactoring opportunity scores - Combine staleness + code complexity to suggest refactoring targets
• Heat Timeline Panel - A webview showing the evolution of code freshness over time
• Predictive stale detection - ML-like heuristic: if a function hasn't been touched but its dependencies have changed, flag it
• Co-author correlation - Show when multiple authors touched the same area recently (conflict risk)
• File-level freshness score - A composite score shown in status bar and explorer
• Freshness diff - Show what changed between "now" and "30 days ago" as a heat annotation
• Git log timeline gutter - Show a sparkline of commit frequency per line in the gutter
• Decay animation - Lines smoothly transition from green → yellow → red as time passes (computed client-side)
• "Churn" heatmap mode - Instead of age, show how many times a line was changed (high churn = unstable)
• Explorer tree decorations - Show freshness badges on files/folders in the explorer
• Freshness report webview - A beautiful dashboard showing stalest files, hottest areas, etc.