Let users cite text selected in rendered HTML visuals

[saibotma]

Summary

In an assistant message, you can select text and cite it into the composer, and that works in Markdown tables too. It doesn't work in rendered HTML visuals, such as the tables, charts or diagrams an agent publishes as an HTML page. Selecting text there never brings up the cite toolbar. Agents tend to put their most important structured results (comparison tables, summaries) in exactly these visuals, so those are the parts users most often want to quote back.

Steps to reproduce

1. Ask an agent for a result that it publishes as an HTML visual, for example a table comparing student counts per school over several months.
2. Select text inside a table cell in the rendered visual.
3. Expected: the cite toolbar appears, the same as for text in the assistant message.
4. Actual: no toolbar appears. The text can be selected and copied, but not cited.

For comparison, a Markdown table in the assistant message text supports citing as expected.

[areidyOTH]

Hitting this too, and I think it's more than a nice-to-have: the html_render tool result tells the agent "Shown to the reader above your reply. Don't mention or describe the page; reply with only what it doesn't already say." So once an agent publishes a render, the substantive answer (tables, chronologies, findings) lives only inside the iframe, and the citable assistant message is reduced to a one-line wrap-up. In practice Cite stops working for most of the answer, not just the visuals.

Repro: agent (Codex) calls t3-code.html_render with a page containing a records table + chronology, then replies with a two-sentence summary. Selecting any text in the inline render → no Cite button. Selecting text in the summary message → Cite works.

Cause (confirmed against source at v0.0.46-nightly.20261008.2833): same as described in #16689. The render is in HtmlRenderDocument (apps/web/src/components/files/BrowserDocumentFrame.tsx) with sandbox="allow-scripts allow-forms" and no allow-same-origin, so the selection is in the frame's document. AssistantSelectionToolbar only listens to the parent's selectionchange/getSelection(), and AssistantCitation can only reference a messageId, not a render attachmentId. Nothing on main since that build touches this path.

Environment:

• T3 Code 0.0.46-nightly.20261008.2833 (a6ec88f7a716), run via npx t3@nightly
• Linux x64 (kernel 7.0), Node v26.8.2
• Provider: Codex

Workaround meanwhile: copy and paste from the render, or ask the agent to repeat key content in markdown, which works against the tool's own instruction.

A small interim option is to soften that tool-result instruction, so agents still put quotable key findings in the reply text until render citations exist.

Triaged with Claude Code (Claude Opus 5.5) via t3 triage.

[Zovea]

I want to be able to cite and comment on text inside rendered HTML. #17023 appears to address that need. I've had agents prepare fixes for the reported readiness timeout and oversized-HTML buffering, with focused regression coverage, on a fork branch linked from #17023. Could a maintainer review the direction and scope of #17023 and say whether this implementation is wanted? I would like to be able to highlight renderings and comment on them the same way I do with regular text output.

[josephv123]

+1, this is most of what I want to quote back now. #17023 looks like it covers renders in the timeline. One related case it leaves out: HTML the agent didn't publish with html_render, such as an .html report already in the workspace opened from the file browser. That preview is a plain iframe, so text there still can't be cited. I added that to #12086, since it is really the "cite from a file" case.

[ViaxCo]

+1. The confusing part for me is that the inline render sits right next to the assistant reply, and text in both selects the same way. So I select text in the render, expect the Cite button, and nothing happens. Nothing tells me that this text works differently from the text above and below it.

#17023 looks like it fixes this. It would be great to get a maintainer review of its direction.