Docstoolsdiffs

Diffs

Diffs

diffs is an optional plugin tool with short built-in system guidance and a companion skill that turns change content into a read-only diff artifact for agents.

It accepts either:

  • before and after text
  • a unified patch

It can return:

  • a gateway viewer URL for canvas presentation
  • a rendered file path (PNG or PDF) for message delivery
  • both outputs in one call

When enabled, the plugin prepends concise usage guidance into system-prompt space and also exposes a detailed skill for cases where the agent needs fuller instructions.

Quick start

  1. Enable the plugin.
  2. Call diffs with mode: "view" for canvas-first flows.
  3. Call diffs with mode: "file" for chat file delivery flows.
  4. Call diffs with mode: "both" when you need both artifacts.

Enable the plugin

{
  plugins: {
    entries: {
      diffs: {
        enabled: true,
      },
    },
  },
}

Disable built-in system guidance

If you want to keep the diffs tool enabled but disable its built-in system-prompt guidance, set plugins.entries.diffs.hooks.allowPromptInjection to false:

{
  plugins: {
    entries: {
      diffs: {
        enabled: true,
        hooks: {
          allowPromptInjection: false,
        },
      },
    },
  },
}

This blocks the diffs plugin's before_prompt_build hook while keeping the plugin, tool, and companion skill available.

If you want to disable both the guidance and the tool, disable the plugin instead.

Typical agent workflow

  1. Agent calls diffs.
  2. Agent reads details fields.
  3. Agent either:
    • opens details.viewerUrl with canvas present
    • sends details.filePath with message using path or filePath
    • does both

Input examples

Before and after:

{
  "before": "# Hello\n\nOne",
  "after": "# Hello\n\nTwo",
  "path": "docs/example.md",
  "mode": "view"
}

Patch:

{
  "patch": "diff --git a/src/example.ts b/src/example.ts\n--- a/src/example.ts\n+++ b/src/example.ts\n@@ -1 +1 @@\n-const x = 1;\n+const x = 2;\n",
  "mode": "both"
}

Tool input reference

All fields are optional unless noted:

  • before (string): original text. Required with after when patch is omitted.
  • after (string): updated text. Required with before when patch is omitted.
  • patch (string): unified diff text. Mutually exclusive with before and after.
  • path (string): display filename for before and after mode.
  • lang (string): language override hint for before and after mode.
  • title (string): viewer title override.
  • mode ("view" | "file" | "both"): output mode. Defaults to plugin default defaults.mode.
  • theme ("light" | "dark"): viewer theme. Defaults to plugin default defaults.theme.
  • layout ("unified" | "split"): diff layout. Defaults to plugin default defaults.layout.
  • expandUnchanged (boolean): expand unchanged sections when full context is available. Per-call option only (not a plugin default key).
  • fileFormat ("png" | "pdf"): rendered file format. Defaults to plugin default defaults.fileFormat.
  • fileQuality ("standard" | "hq" | "print"): quality preset for PNG or PDF rendering.
  • fileScale (number): device scale override (1-4).
  • fileMaxWidth (number): max render width in CSS pixels (640-2400).
  • ttlSeconds (number): viewer artifact TTL in seconds. Default 1800, max 21600.
  • baseUrl (string): viewer URL origin override. Must be http or https, no query/hash.

Validation and limits:

  • before and after each max 512 KiB.
  • patch max 2 MiB.
  • path max 2048 bytes.
  • lang max 128 bytes.
  • title max 1024 bytes.
  • Patch complexity cap: max 128 files and 120000 total lines.
  • patch and before or after together are rejected.
  • Rendered file safety limits (apply to PNG and PDF):
    • fileQuality: "standard": max 8 MP (8,000,000 rendered pixels).
    • fileQuality: "hq": max 14 MP (14,000,000 rendered pixels).
    • fileQuality: "print": max 24 MP (24,000,000 rendered pixels).
    • PDF also has a max of 50 pages.

Output details contract

The tool returns structured metadata under details.

Shared fields for modes that create a viewer:

  • artifactId
  • viewerUrl
  • viewerPath
  • title
  • expiresAt
  • inputKind
  • fileCount
  • mode

File fields when PNG or PDF is rendered:

  • filePath
  • path (same value as filePath, for message tool compatibility)
  • fileBytes
  • fileFormat
  • fileQuality
  • fileScale
  • fileMaxWidth

Mode behavior summary:

  • mode: "view": viewer fields only.
  • mode: "file": file fields only, no viewer artifact.
  • mode: "both": viewer fields plus file fields. If file rendering fails, viewer still returns with fileError.

Collapsed unchanged sections

  • The viewer can show rows like N unmodified lines.
  • Expand controls on those rows are conditional and not guaranteed for every input kind.
  • Expand controls appear when the rendered diff has expandable context data, which is typical for before and after input.
  • For many unified patch inputs, omitted context bodies are not available in the parsed patch hunks, so the row can appear without expand controls. This is expected behavior.
  • expandUnchanged applies only when expandable context exists.

Plugin defaults

Set plugin-wide defaults in ~/.openclaw/openclaw.json:

{
  plugins: {
    entries: {
      diffs: {
        enabled: true,
        config: {
          defaults: {
            fontFamily: "Fira Code",
            fontSize: 15,
            lineSpacing: 1.6,
            layout: "unified",
            showLineNumbers: true,
            diffIndicators: "bars",
            wordWrap: true,
            background: true,
            theme: "dark",
            fileFormat: "png",
            fileQuality: "standard",
            fileScale: 2,
            fileMaxWidth: 960,
            mode: "both",
          },
        },
      },
    },
  },
}

Supported defaults:

  • fontFamily
  • fontSize
  • lineSpacing
  • layout
  • showLineNumbers
  • diffIndicators
  • wordWrap
  • background
  • theme
  • fileFormat
  • fileQuality
  • fileScale
  • fileMaxWidth
  • mode

Explicit tool parameters override these defaults.

Security config

  • security.allowRemoteViewer (boolean, default false)
    • false: non-loopback requests to viewer routes are denied.
    • true: remote viewers are allowed if tokenized path is valid.

Example:

{
  plugins: {
    entries: {
      diffs: {
        enabled: true,
        config: {
          security: {
            allowRemoteViewer: false,
          },
        },
      },
    },
  },
}

Artifact lifecycle and storage

  • Artifacts are stored under the temp subfolder: $TMPDIR/openclaw-diffs.
  • Viewer artifact metadata contains:
    • random artifact ID (20 hex chars)
    • random token (48 hex chars)
    • createdAt and expiresAt
    • stored viewer.html path
  • Default viewer TTL is 30 minutes when not specified.
  • Maximum accepted viewer TTL is 6 hours.
  • Cleanup runs opportunistically after artifact creation.
  • Expired artifacts are deleted.
  • Fallback cleanup removes stale folders older than 24 hours when metadata is missing.

Viewer URL and network behavior

Viewer route:

  • /plugins/diffs/view/{artifactId}/{token}

Viewer assets:

  • /plugins/diffs/assets/viewer.js
  • /plugins/diffs/assets/viewer-runtime.js

URL construction behavior:

  • If baseUrl is provided, it is used after strict validation.
  • Without baseUrl, viewer URL defaults to loopback 127.0.0.1.
  • If gateway bind mode is custom and gateway.customBindHost is set, that host is used.

baseUrl rules:

  • Must be http:// or https://.
  • Query and hash are rejected.
  • Origin plus optional base path is allowed.

Security model

Viewer hardening:

  • Loopback-only by default.
  • Tokenized viewer paths with strict ID and token validation.
  • Viewer response CSP:
    • default-src 'none'
    • scripts and assets only from self
    • no outbound connect-src
  • Remote miss throttling when remote access is enabled:
    • 40 failures per 60 seconds
    • 60 second lockout (429 Too Many Requests)

File rendering hardening:

  • Screenshot browser request routing is deny-by-default.
  • Only local viewer assets from http://127.0.0.1/plugins/diffs/assets/* are allowed.
  • External network requests are blocked.

Browser requirements for file mode

mode: "file" and mode: "both" need a Chromium-compatible browser.

Resolution order:

  1. browser.executablePath in OpenClaw config.
  2. Environment variables:
    • OPENCLAW_BROWSER_EXECUTABLE_PATH
    • BROWSER_EXECUTABLE_PATH
    • PLAYWRIGHT_CHROMIUM_EXECUTABLE_PATH
  3. Platform command/path discovery fallback.

Common failure text:

  • Diff PNG/PDF rendering requires a Chromium-compatible browser...

Fix by installing Chrome, Chromium, Edge, or Brave, or setting one of the executable path options above.

Troubleshooting

Input validation errors:

  • Provide patch or both before and after text.
    • Include both before and after, or provide patch.
  • Provide either patch or before/after input, not both.
    • Do not mix input modes.
  • Invalid baseUrl: ...
    • Use http(s) origin with optional path, no query/hash.
  • {field} exceeds maximum size (...)
    • Reduce payload size.
  • Large patch rejection
    • Reduce patch file count or total lines.

Viewer accessibility issues:

  • Viewer URL resolves to 127.0.0.1 by default.
  • For remote access scenarios, either:
    • pass baseUrl per tool call, or
    • use gateway.bind=custom and gateway.customBindHost
  • Enable security.allowRemoteViewer only when you intend external viewer access.

Unmodified-lines row has no expand button:

  • This can happen for patch input when the patch does not carry expandable context.
  • This is expected and does not indicate a viewer failure.

Artifact not found:

  • Artifact expired due TTL.
  • Token or path changed.
  • Cleanup removed stale data.

Operational guidance

  • Prefer mode: "view" for local interactive reviews in canvas.
  • Prefer mode: "file" for outbound chat channels that need an attachment.
  • Keep allowRemoteViewer disabled unless your deployment requires remote viewer URLs.
  • Set explicit short ttlSeconds for sensitive diffs.
  • Avoid sending secrets in diff input when not required.
  • If your channel compresses images aggressively (for example Telegram or WhatsApp), prefer PDF output (fileFormat: "pdf").

Diff rendering engine:

文档内容基于 OpenClaw 官方文档（MIT License）