ThunderClaw

OpenClaw-powered writing and reading assistance for Thunderbird.
Your inbox, your decisions, your control.

Features · Safety · Installation · Development · Contributing

Important

ThunderClaw v0.1.0 is available now. Install the extension from Thunderbird Add-ons and its matching OpenClaw plugin from ClawHub.

Note

OpenClaw requirement: ThunderClaw requires OpenClaw 2026.7.2-beta.7 or newer. See the compatibility policy for details.

AI assistance without handing over your inbox

ThunderClaw brings useful writing and reading tools into desktop Thunderbird while keeping Thunderbird—and you—in charge. A model can propose an edit, summary, or translation. It cannot send mail, silently rewrite a message, or change recipients, attachments, or headers.

Every compose change follows the same deliberate flow:

Generate → Preview → Apply → Undo

The current Thunderbird content remains authoritative throughout. Results are validated on both sides of the connection, and stale results fail closed.

See it in action

Preview a writing improvement before choosing whether to apply it to the draft:

Reading tools keep generated results separate from the original message and make them easy to dismiss or reverse.

Summarize a message	Translate in place

What it can do

In the composer	In a received message
Improve, proofread, shorten, or change tone	Create a separate plain-text summary card
Translate or summarize selected draft text	Reversibly translate visible message text
Follow a custom writing instruction	Preserve the message's original HTML structure
Preview before applying and undo afterward	Leave the original message untouched

Thunderbird 128 and newer support plain selected-text transformations. Qualified Thunderbird 153 and newer selections can also preserve or produce narrowly typed rich content: paragraphs, flat lists, and bold, italic, or underlined spans. Unsupported shapes are rejected rather than guessed at.

See the product contract for exact capability and eligibility rules.

Data sent to OpenClaw

ThunderClaw sends email content only after you invoke a writing, translation, or summary action:

• Compose actions send the selected target, the entire visible authored draft body, extracted quoted message history, subject, and To/Cc/Bcc recipients.
• Message actions send the entire visible rendered message body—including visible quoted history and signatures—plus its subject and author.

ThunderClaw does not send attachment contents, hidden message content, or message headers other than those listed above through its transformation routes. The content passes through the OpenClaw Gateway you configure to the selected agent and configured model provider. Configured fallback providers and hooks installed in that Gateway may also process it. ThunderClaw's developer operates no service that receives this content.

Read the full privacy policy before use.

How it stays safe

Email is untrusted input, so ThunderClaw is intentionally narrow by design.

• Thunderbird owns every mutation. Models return strictly validated data, never HTML to insert into a message.
• Sending stays ordinary and manual. ThunderClaw cannot invoke Send or alter recipients, attachments, or headers.
• Model runs are isolated. The selected compatible OpenClaw agent runs with in-memory sessions, model-callable tools disabled, and trajectory disabled.
• Results are bound to their context. Request identity, generation, target hashes, context hashes, output limits, and segment IDs prevent stale or misplaced changes.
• Credentials stay scoped. Thunderbird stores only its narrow paired ThunderClaw credential—never provider keys or a broad Gateway token.
• The boundary is reviewable. The extension and plugin communicate only over fixed HTTP(S) routes, with independent validators on each side.

Read the full security and privacy model and architecture.

Architecture

ThunderClaw has exactly two independently packaged components:

flowchart LR
    U["You in Thunderbird"] -->|"Generate / Preview / Apply / Undo"| T["Thunderbird MailExtension"]
    T -->|"Fixed HTTP(S) routes<br>strict JSON contracts"| P["ThunderClaw OpenClaw plugin"]
    P -->|"Restricted, isolated run"| A["Your configured compatible agent"]
    T -.->|"Only Thunderbird mutates<br>message and compose DOM"| M["Mail content"]

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There is no native helper, Native Messaging host, alternate transport, or OpenClaw core patch. Provider, model, agent, and provider-key configuration remain in OpenClaw.

Installation and pairing

ThunderClaw requires OpenClaw 2026.7.2-beta.7 or newer. See the compatibility policy before installing.

Install both matching v0.1.0 components:

1. Install ThunderClaw from its Thunderbird Add-ons listing.

2. Install and enable the @thunderclaw/openclaw-plugin package on ClawHub on the OpenClaw host:

   openclaw plugins install clawhub:@thunderclaw/openclaw-plugin
   openclaw plugins enable thunderclaw
   openclaw gateway restart

Thunderbird initiates pairing and displays a short approval code. An authenticated OpenClaw operator approves the matching request with:

openclaw thunderclaw

The user then explicitly claims that approval in Thunderbird. Approval and claim are separate decisions; neither happens automatically. See installation and pairing for the complete flow and development for running from source today.

Development

ThunderClaw uses Node.js through mise:

mise exec -- npm ci
mise exec -- npm test
mise exec -- npm run typecheck
mise exec -- npm run build

The monorepo keeps both sides of the boundary reviewable together while packaging them independently:

packages/openclaw-plugin/         OpenClaw plugin and package metadata
packages/thunderbird-extension/   Thunderbird extension source and icons
test/                             Unit, contract, lifecycle, and boundary tests
e2e/                              Real Thunderbird and qualification tooling
fixtures/                         Cross-boundary conformance fixtures
scripts/                          Build and qualification entry points
docs/                             Product, protocol, security, and release docs

Shared fixtures test conformance, but each component independently validates the runtime contract across the HTTP boundary. Start with the development guide, testing guide, and contribution guide.

Project status

ThunderClaw v0.1.0 is the first public release and is available from Thunderbird Add-ons and ClawHub. The roadmap is the authoritative list of unfinished work and post-release hardening.

Bug reports, documentation improvements, tests, and focused code changes are welcome. For substantial behavior, protocol, dependency, or UI changes, please open an issue before investing in an implementation.

Documentation

• Architecture — component ownership and data flow
• Product contract — supported behavior and review boundaries
• Compatibility — supported runtimes and upgrade policy
• Security and privacy — trust, credentials, disclosure, and residual risks
• Privacy policy — ATN-ready data practices and listing disclosure collateral
• Installation and pairing — installation and operator/user pairing
• Development — development environment and plugin updates
• Testing — test layers and qualification matrices
• Release process — artifact acceptance and publication policy
• Protocol reference — normative boundary contracts
• Brand — assets, specification, licensing, and provenance

Community and license

Please read CONTRIBUTING.md before opening a pull request and use SECURITY.md for private vulnerability reports. Community participation is governed by the Code of Conduct.

Code, documentation, and project-owned assets are licensed under the Apache License 2.0. The ThunderClaw name, logo, and character are also covered by the trademark policy.

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