Skills

explain-diff-html: A Claude Code Skill That Turns PRs and Code Diffs into a One-Page HTML Explanation

Best suited when you want to turn a PR or code diff into a single self-contained HTML explanation in Claude Code. You need a POSIX shell environment (Linux/macOS or WSL/Git Bash) and git; explaining PRs also requires an authenticated gh. Generated pages are saved under code-explanations in your home directory.

Official source · explain-diff-html

Install

git clone https://github.com/malav2110/explain-diff-html.git ~/.claude/skills/explain-diff-html

Who It's For

  • Ideal for anyone who wants to quickly understand a code change in Claude Code: for example, taking over an unfamiliar repository, reviewing someone else's PR, or leaving teammates a shareable explanation of "what exactly changed and why."
  • It turns code changes into a single self-contained HTML teaching page, written outside your repository — it never touches your code.
  • When it's not a fit: you don't work in Claude Code, you need PowerShell or cmd.exe (officially unsupported — a POSIX shell is required), or you want to modify or roll back code (it only generates explanation pages). Every run requires git; explaining pull requests requires an authenticated gh (check with gh auth status); pages using Mermaid diagrams load the diagram library from a CDN and need network access. Beyond this, no undocumented dependencies or limitations are stated by the official source, and this article makes no guesses.

Your First Try in 3 Minutes

Prerequisites: Claude Code installed; environment is Linux, macOS, or WSL / Git Bash on Windows; git available locally.

Installation: clone the repository into Claude Code's global skills directory (the official primary path):

git clone https://github.com/malav2110/explain-diff-html.git \
  ~/.claude/skills/explain-diff-html

If you only want to use it in a specific project, the official instructions say to clone into <your-repo>/.claude/skills/explain-diff-html instead.

For your first task, pick a low-risk, read-only attempt: initiate it in Claude Code with a single natural-language prompt, e.g. "explain PR 1234" (pointing at a PR in a public repository you can only observe, not merge). This action requires nothing beyond gh, but first confirm gh auth status passes.

Success signal: the skill writes the explanation page to a code-explanations folder in your home directory, with a filename like YYYY-MM-DD-<KEY>-explanation.html, and reports the path back to you. Seeing that path and the generated HTML file means it's done. Note: pages that only explain code open offline; if the page contains Mermaid state or sequence diagrams, you need internet to render the graphics.

The official source only states that its commands use a POSIX shell; it does not state whether it reads or writes other files, what internal commands it runs, or which network endpoints it accesses. These behaviors are unknown.

Use Cases

Case 1: Understanding a PR. Scenario: you need to understand a change in an unfamiliar open-source repository. Say "explain PR 1234" in Claude Code. The skill follows its PR explanation flow and generates a single HTML page explaining the logic of the change. Expected result: a date-named page under $HOME/code-explanations, provided gh is authenticated. Whether the page contains Mermaid diagrams depends on the change itself; if it does, opening the page requires internet.

Case 2: Understanding a local diff. Scenario: you've just committed or pulled a change and want to explain it clearly to your team. In Claude Code, use natural language to ask it to explain the change. What's confirmed: it produces the same kind of self-contained HTML teaching page, writes it to the same code-explanations directory, and reports the path. The official source doesn't list specific command wording for local diffs, so all that's confirmable is "describe the change in one natural-language sentence"; for exact trigger phrasing, defer to the repository README.

Boundaries of Use

  • Files and network: it writes generated HTML to $HOME/code-explanations (deliberately placed outside the repository) and never writes into your repo; pages with Mermaid diagrams load the library from a CDN and require network access. Beyond this, whether it reads or writes other files or what commands it runs is not stated by the official source.
  • Points to confirm: run gh auth status before explaining a PR to confirm authentication; the generation itself creates new HTML files, so users who mind new files being created should be aware before initiating.
  • Runtime environment: Linux and macOS work out of the box; Windows requires WSL or Git Bash; PowerShell and cmd.exe are explicitly unsupported. Every run needs git; PR scenarios need an authenticated gh; validating Mermaid diagrams requires node via npx.
  • Official limitations: output is always written to the code-explanations folder in the home directory; pages are self-contained and work offline except for the Mermaid CDN.
  • Unconfirmed information: the official source does not state which text languages it supports or whether it works with other agents besides Claude Code. Check the repository's latest documentation rather than inferring from client lists.