capture-via-dom

name	capture-via-dom
description	Fallback capture of a ChatGPT conversation by scraping the rendered DOM with scrolling. Use only when capture-via-api fails. Lossy - no timestamps, branches, tool messages or artifact payloads.

Capture by scraping the DOM

Fallback only. Use after capture-via-api has actually failed, not instead of trying it. When you use this route, tell the user the capture is lossy and why.

Why it is lossy

The message list is virtualised. On a 34-message thread only about five messages exist in the DOM at any scroll position, and data-testid indices start wherever the viewport happens to be — conversation-turn-6, not -1. A single-pass querySelectorAll therefore returns a handful of messages and looks like a complete short conversation. That is the failure worth guarding against: it does not error, it just silently returns a fraction.

The script scrolls the container from the top and accumulates by data-message-id, which handles the virtualisation. It still cannot recover:

• per-message timestamps (created_at is null throughout)
• alternate branches from edited or regenerated turns
• hidden and tool messages
• canvas document payloads — only the rendered preview text survives
• image asset pointers and citation URLs as structured data

Steps

1. Ensure the conversation tab is open and fully loaded.
2. Read ${CLAUDE_PLUGIN_ROOT}/scripts/browser/capture-via-dom.js and pass it to javascript_tool. Scrolling takes several seconds on a long thread.
3. The download it writes is already normalized — it is emitted in the normalizer's schema. Skip normalize_conversation.py and go straight to a renderer.

Verifying the capture

Scroll capture is the kind of thing that half-works. Before rendering, sanity check:

python3 -c "import json,sys; d=json.load(open(sys.argv[1])); s=d['stats']; \
print(s['total_turns'],'turns',s['user_messages'],'user',s['assistant_messages'],'assistant')" <file>

Compare against what the user says the thread contains, and against the turn counter visible in the ChatGPT UI. If the count looks short, scroll to the top of the thread manually and re-run rather than accepting it.

stats.capture_is_lossy is true in every file this route produces, and unhandled carries a note explaining what is missing. Leave both in place — they are how a later reader knows the transcript is partial.