# Diffs

> Use the diffs tool to produce real, shareable diffs (viewer URL, file artifact, or both) instead of manual edit summaries.

- Skill: `grtninja/diffs` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add grtninja/diffs`
- Raw SKILL.md: https://api.skillmd.com/api/skills/grtninja/diffs/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: grtninja (https://skillmd.com/u/grtninja)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/grtninja/diffs

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When you need to show edits as a real diff, prefer the `diffs` tool instead of writing a manual summary.

The `diffs` tool accepts either `before` + `after` text, or a unified `patch` string.

Use `mode=view` when you want an interactive gateway-hosted viewer. After the tool returns, use `details.viewerUrl` with the canvas tool via `canvas present` or `canvas navigate`.

Use `mode=file` when you need a rendered file artifact. Set `fileFormat=png` (default) or `fileFormat=pdf`. The tool result includes `details.filePath`.

For large or high-fidelity files, use `fileQuality` (`standard`|`hq`|`print`) and optionally override `fileScale`/`fileMaxWidth`.

When you need to deliver the rendered file to a user or channel, do not rely on the raw tool-result renderer. Instead, call the `message` tool and pass `details.filePath` through `path` or `filePath`.

Use `mode=both` when you want both the gateway viewer URL and the rendered artifact.

If the user has configured diffs plugin defaults, prefer omitting `mode`, `theme`, `layout`, and related presentation options unless you need to override them for this specific diff.

Include `path` for before/after text when you know the file name.

## Guardrails

- Use local or trusted tools only; avoid untrusted install pipelines.
- Do not paste secrets/tokens into chat output.
- Keep outputs in deterministic local paths for reproducible review.