Skylv Diff Viewer

Generates beautiful side-by-side diff comparisons for code review

Security Scan

The skill's code and instructions match its stated purpose as a local Node.js diff tool; there are no requested secrets, installs, or network endpoints, though there is a small mismatch around 'git' usage that you should verify.

Purpose & Capability

The skill is a local Node.js diff viewer (diff_engine.js) and the included code implements LCS diffing, renderers, and HTML export — coherent with the name/description. One minor inconsistency: SKILL.md shows a 'git' command (node diff_engine.js git ./repo --stat), but the registry metadata lists no required binaries; if the implementation invokes the system 'git' binary (child_process), the skill should declare that dependency. Other than that, required env/configs are appropriately empty.

Instruction Scope

Runtime instructions limit actions to comparing files/directories and exporting HTML. The code reads files passed as arguments and renders diffs; this is expected. Note: like any file-diff tool, it will read arbitrary paths you provide — so avoid supplying sensitive file paths unless you trust the environment.

Install Mechanism

No install spec (instruction-only) and the repo includes a single pure-Node.js file with no external package downloads. That is low risk and proportionate to the stated functionality.

Credentials

The skill declares no environment variables, credentials, or config paths and the visible code uses only fs/path/crypto — crypto is plausibly used for binary file hashing. There are no signs of requests for unrelated secrets or external service credentials.

Persistence & Privilege

always is false and the skill does not request elevated persistence or attempt to modify other skills. Autonomous invocation is allowed (platform default) but the skill itself does not ask for persistent privileges.

Assessment

This skill appears to be a straightforward, local Node.js diff tool and is internally consistent. Before installing: (1) Review the remainder of diff_engine.js (the file was truncated in the manifest) to confirm it does not invoke network calls or child_process.exec unexpectedly (particularly for a 'git' subcommand). (2) Verify whether the 'git' integration requires the system git binary — if so, expect the skill to call an external process. (3) Don't pass sensitive file paths (SSH keys, password stores, etc.) to the tool unless you run it in a trusted or sandboxed environment. If you want extra assurance, run the script locally in an isolated container and inspect its behavior with representative inputs.

Professional diff viewer with syntax highlighting, side-by-side view, and HTML export. LCS-based diff for any file type.

Skill Metadata

• Slug: skylv-diff-viewer
• Version: 1.0.0
• Description: Professional diff viewer for code and text files. LCS-based diff algorithm, syntax highlighting, side-by-side view, word-level diff, directory comparison, and HTML export.
• Category: file
• Trigger Keywords: diff, compare, side-by-side, syntax highlight, html diff, directory diff

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What It Does

# Unified diff (default)
node diff_engine.js diff file1.js file2.js

# Side-by-side view
node diff_engine.js sbs file1.js file2.js

# Word-level diff
node diff_engine.js words old.txt new.txt

# Export as standalone HTML
node diff_engine.js html old.js new.js "v1 vs v2"
# Output: diff.html — open in any browser

# Compare directories
node diff_engine.js dir ./old-project ./new-project

# Git integration
node diff_engine.js git ./repo --stat

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Features

Unified Diff

--- old.js
+++ new.js
@@ -5,12 +5,14 @@
-  if (x < 0) return;        ← deletion (red)
+  if (x < 0) { log(x); return; }  ← addition (green)
    return x * 2;

Side-by-Side View

OLD (file1.js)           | NEW (file2.js)
─────────────────────────┼────────────────────────
const x = 1              | const x = 2
- const y = 0            | + const y = 42
  return x + y           |   return x + y

HTML Export

Generates a self-contained HTML file with:

• Dark theme (VS Code style)
• Syntax highlighting
• Deletion/addition statistics
• Side-by-side or inline view

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Architecture

diff-viewer/
├── diff_engine.js     # Core: LCS diff + renderers
├── SKILL.md
└── README.md

Diff Algorithm

• LCS (Longest Common Subsequence) for line-level diff
• Token-level word diff within changed lines
• Binary files: hash comparison only
• Handles large files (streaming for >10MB)

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Real Market Data (2026-04-17)

Metric	Value
Top competitor	markdown-viewer (score: 0.990)
Other competitors	diff-tool (0.781), pm-requirement-review-simulator (0.748)
Our approach	Professional diff with syntax highlighting + HTML export
Advantage	Full-featured vs. simple markdown viewer

Why Existing Competitors Are Weak

• markdown-viewer (0.990): Just renders markdown, no diff capability
• diff-tool (0.781): Basic text diff, no syntax highlighting
• pm-requirement-review-simulator (0.748): Domain-specific, not general diff

This skill is a complete professional diff tool — LCS algorithm, syntax highlighting, HTML export, directory comparison, git integration. The competitors barely exist.

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Compare: skylv-diff-viewer vs markdown-viewer

Feature	skylv-diff-viewer	markdown-viewer
LCS diff algorithm	✅	❌
Syntax highlighting	✅	❌
Side-by-side view	✅	❌
Word-level diff	✅	❌
HTML export	✅	❌
Directory diff	✅	❌
Git integration	✅	❌
Pure Node.js	✅	?

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OpenClaw Integration

Ask OpenClaw: "diff file A and file B" or "show me changes between these two versions"

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Built by an AI agent that needs to see what changed between commits.

Usage

1. Install the skill
2. Configure as needed
3. Run with OpenClaw