---
title: Supermail Video Summaries (Loom & Vimeo)
---
# Supermail Video Summaries (Loom & Vimeo)

## What it is

**Video summaries** are an optional AI helper in Supermail. When an **incoming** message
contains a **Loom** or **Vimeo** video link, it reads the video for you and shows a short,
AI-written summary card inside the message — so you can tell what a video is about before
deciding whether to watch it.

It is **in development and off by default** — hidden until you turn it on in
Settings → Features (the `supermailVideoSummariesEnabled` Lab toggle). When off, nothing
runs and no card appears. It is the video-reading sibling of Supermail's other AI helpers,
[AI Summary](supermail-ai-summary.md) (summarizes a thread) and
[AI Filtering](supermail-ai-filtering.md) (triages new mail).

## Where to find it

In development and off by default — reveal it from **Settings → Features**. The summary card then appears inside the message that carries the link.

## How it behaves

### How it works

Shaped by Supermail's architecture (the mailbox UI lives in the vendored plugin; the AI
keys + spend live only in the main process):

- **The paid AI runs in the main process.** The renderer sends only `{threadId, host,
  videoId}` — it never sends the message body or the video URL. Main orchestrates the whole
  pipeline: fetch the video's **captions** → if none, download the audio and
  **auto-transcribe** it → summarize the resulting text with the LLM → return the summary.
  The LLM key and the transcription key never reach the renderer.
- **Captions first, transcription as the fallback.** Loom and Vimeo both expose captions
  for most videos; when they exist, they are used (the card notes "Captions"). When a video
  has no usable captions, the audio is transcribed instead via the same Groq Whisper engine
  the app's voice features use (the card notes "Audio transcription"). If transcription isn't
  available either (no key, download failed, audio too big), the card shows an honest note —
  it never hangs and never silently shows nothing.
- **Joined by a desktop-only bridge/IPC channel** (`SUPERMAIL_VIDEO_SUMMARY`), blocked over
  the mobile web bridge: it spends AI credit and works off the desktop app's keys.
- The summary renders as a **dismissible card** at the top of the message reading area, with
  a "Watch video" link to the source.

Code: `src/main/services/supermail/supermail-video-summary-*.ts` (main) and
`src/plugins/supermail/ui/src/features/conversation/` (`use-video-summary.ts` +
`video-summary-card.tsx` + `detect-video-links.ts`).

### When it runs — automatic, incoming only

- The card appears **automatically** when you open a message that contains a Loom or Vimeo
  link and the feature is on. There is no button to press.
- It only runs for **incoming** messages (sent *to* you) — outgoing and draft messages never
  trigger a paid call.
- It summarizes **one video per message** (the first Loom/Vimeo link); other links are left
  untouched.
- To avoid re-billing, the result is cached **in memory** per (message, video) for the app
  session — re-opening the same message reuses the summary instead of re-running.

### Cost + safety

- **Cost-capped.** Every summary call is cost-tracked (`source: supermail-video-summary`)
  and refused with a friendly "daily limit reached" state once a **main-side daily cap** (a
  constant, not renderer-tunable) is hit.
- **Video content is untrusted and fenced.** Captions/transcripts are third-party content,
  not instructions: they are wrapped in sentinel fences (forged fence markers neutralized),
  scrubbed of contact details (email / phone / SSN patterns), truncated to a bounded window,
  and the model is told to output only a summary. A prompt-injection attempt inside a video
  can at most alter the summary's prose — it executes nothing.
- **It fetches only the video id, from the fixed host.** The fetcher never follows the raw
  message URL. It extracts the video id (Loom 32-char hex / Vimeo numeric) and pulls the
  transcript only from Loom's GraphQL transcript endpoint or Vimeo's player config — with a
  bounded timeout and one retry.
- **Where your video's text goes.** The caption/transcript text is sent to the app's AI
  providers (LLM + transcription) to produce the summary. This only happens on a message you
  open, with the feature on.
- **Fails honest.** Feature off / no key / fetch failed / too big → a clear "unavailable"
  state, never a silent blank.

## Related

The other Supermail AI helpers each have their own page — AI Filtering, Catch me up, Assistants and the AI Digest.