dsh-image-preview

Inline image previews for the built-in DeepSeek Harness read_image tool.

The plugin uses DSH's public, session-scoped tool.call.toolview slot. Because the official tool tree dispatches nested subcalls through the same slot, one renderer covers both:

• direct read_image calls; and
• tools.read_image(...) calls nested inside run_code Code Mode.

Every loaded preview includes Copy image with visible success or failure feedback. PNG bytes are copied directly when supported; other accepted formats are converted to PNG in-browser when necessary.

Security and lifecycle

• Bytes are fetched only through ctx.sessions.binding(sessionId).session.readAttachment(attachmentId).
• The model-supplied file path is display/navigation metadata only and is never reread by the browser plugin.
• Only authenticated PNG, JPEG, WebP, and GIF attachment responses are rendered.
• Blob URLs are revoked on replacement, retry, unmount, and HMR disposal.
• Clipboard copies use the same authenticated attachment blob; bounded in-browser conversion never rereads the model-supplied path or adds a network fallback.
• Malformed/legacy results and attachment RPC failures degrade to a bounded inline error with no filesystem or network fallback.

Settings

The plugin contributes an Image previews card under DSH Settings → Plugins with two live, persisted options:

• Enable inline previews — disabling it removes the custom renderer and restores DSH's generic tool row.
• Open previews automatically — when disabled, each image starts collapsed and loads only after Show preview is clicked.

Development

pnpm install
pnpm check

The package follows the official Harness plugin guide: it exports a function-form host plugin, declares a dsh.bundle patch, exposes a Web client entry, declares its injected public packages, and owns explicit cleanup through lifecycle effects.

Install into a profile

A tarball avoids git-build permissions and is robust when the checkout path contains spaces:

pnpm pack --pack-destination "$HOME/.dsh/packages"
dsh plugin --profile web add "$HOME/.dsh/packages/dsh-image-preview-0.3.0.tgz"
dsh --profile web --dump-config

The install command adds the package dependency and appends dsh-image-preview to the profile's ordered bundle list. Refresh the page after the running Web profile has loaded the new bundle; a first-time host mount requires an operator-approved Web restart.