openchamber/packages/web/server/lib/markdown-image-grants/DOCUMENTATION.md

Markdown Image Grants

Purpose

This module lets the Markdown image gallery display images that an assistant explicitly referenced from OpenCode's temporary directory when the UI is on a different machine.

Contract

• Chat Markdown rendering is independent: assistant image syntax renders as an icon and filename, while the gallery only reads finalized Markdown to collect image candidates.
• POST /api/openchamber/sessions/:sessionId/markdown-image-grants prepares up to 12 local images in one message-level request. The server fetches the assistant message once and verifies every exact image source before reading files.
• Relative and workspace-contained absolute paths resolve against the active directory. Other absolute paths are accepted only inside os.tmpdir()/opencode after realpath resolution.
• PNG, JPEG, GIF, and WebP files are signature-checked and limited to 10 MiB.
• Prepare requests inspect only file metadata and signatures. Workspace images reuse the existing authenticated /api/fs/raw asset route directly. Images under os.tmpdir()/opencode receive the existing path-bound raw outsideFileGrant; this module does not add another asset lifetime, copy, or storage layer. Missing files return per-source results so the gallery can remove only those items.

The routes are OpenChamber-owned and must be registered before the generic OpenCode proxy. Web, Electron, hosted mobile, and Capacitor use the shared server implementation. VS Code returns an explicit unsupported response.