Agentic UI: add a native text context menu

[shaunandrews]

Related issues

• Related to Agentic UI: fix copy button space in chat #4334 (the copy button work this grew out of)

How AI was used in this PR

AI wrote the implementation and tests from a scope I set interactively. I reviewed the approach, iterated on the menu behavior from review feedback, and tested it in the app.

Proposed Changes

Right-click previously did nothing in Studio’s Agentic UI because Electron does not provide Chromium’s browser context menu automatically. This adds a native operating-system menu while keeping browser builds on their existing browser-provided menu.

Action	When it appears
Look Up “…”	macOS, when text is selected
Copy	When text is selected, including selected composer text
Copy code	When right-clicking a rendered code block
Copy All	When right-clicking a user or assistant message
Paste	In an editable text field when the clipboard contains text
Quote in composer	When read-only text is selected

Copy All is message-level: assistant replies split by tool calls still copy all assistant text blocks. Tool details and tool output are not included. Code blocks retain their existing copy button, and the native menu’s Copy code action copies only the code block.

Quote in composer formats each selected line as a Markdown blockquote and leaves a blank line after it, with the composer focused and ready for the user to continue typing.

Every item is conditional on whether it can do something. Non-text inputs, read-only fields without a selection, unrelated controls, and empty canvas do not open an irrelevant menu. Undo, redo, cut, and delete remain deliberately outside this focused first pass.

Testing Instructions

This includes main-process code, so fully restart the app before testing.

1. Send a message that includes normal text and a fenced code block.
2. Select text in an assistant reply and right-click.
   • macOS: Look Up, Copy, Copy All, and Quote in composer.
   • Windows/Linux: Copy, Copy All, and Quote in composer.
3. Choose Quote in composer. Confirm the selected text is inserted as a Markdown quote followed by a blank line, with the caret ready for typing.
4. Right-click a code block. Confirm Copy code copies only the code while Copy All copies the full assistant message.
5. Right-click earlier and later paragraphs of a reply split by a tool call. Confirm Copy All produces the same complete assistant message from either paragraph.
6. Select text in the composer and right-click. Confirm Copy appears; with text on the clipboard, Paste also appears.
7. Right-click a message with no selection. Confirm only the applicable message/code actions appear.
8. Right-click unrelated UI, a checkbox, or empty canvas. Confirm no text menu opens.
9. On macOS, choose Look Up and confirm the system Dictionary panel opens.
10. Select a long passage and confirm the Look Up label collapses whitespace and truncates with an ellipsis.

Pre-merge Checklist

• Have you checked for TypeScript, React or other console errors?

Notes for reviewers:

• ESLint passes for all touched TypeScript files.
• npm run typecheck passes across all workspaces.
• npm run cli:build:ui completes successfully.
• The native-menu test plus the full apps/ui suite pass: 71 files, 508 tests.

[wpmobilebot]

📊 Performance Test Results

Comparing 6432fd3 vs trunk

app-size

Metric	trunk	6432fd3	Diff	Change
App Size (Mac)	1402.94 MB	1402.95 MB	+0.01 MB	⚪ 0.0%

site-editor

Metric	trunk	6432fd3	Diff	Change
load	1072 ms	1052 ms	20 ms	⚪ 0.0%

site-startup

Metric	trunk	6432fd3	Diff	Change
siteCreation	7548 ms	7539 ms	9 ms	⚪ 0.0%
siteStartup	2878 ms	2865 ms	13 ms	⚪ 0.0%

---

Results are median values from multiple test runs.

Legend: 🟢 Improvement (faster) | 🔴 Regression (slower) | ⚪ No change (<50ms diff)

[bcotrim]

Looks good!

Some comments:

1. On the composer only "Paste" is available, should we also offer "Copy"?

2. "Copy All" is a translated string. Should the other options also be translated?
   menu.ts:364-366 already does { label: __( 'Copy' ), role: 'copy' } — macOS
   localizes roles natively, so this would only show on Windows/Linux.

3. conversation/index.tsx:473 uses copyText ?? text, but copyText is only set on
   the last text block (line 281). On a reply split by tool calls, right-clicking an
   earlier paragraph makes "Copy All" copy just that fragment — the comment on line 262 says it should yield the whole message.

Suggestion: what do you think about an option to quote the selected text into the
composer? Could be useful for referencing part of the agent's reply. Could be done in a follow-up PR if you think it's a good idea

[katinthehatsite]

Nice work! I saw that the changes Bernardo mentioned were already implemented ❤️

I left some minor suggestions and a couple of questions but nothing that is blocking

[shaunandrews]

@bcotrim thanks for the review.

1. Added! Now you can copy text in the composer.
2. I added __() calls for all the options, so they should get translated.
3. Fixed!

I also added your suggestion to let users quote text into their composer.

@katinthehatsite I implemented your suggestions as well!

Let me know whatcha thinK!

[bcotrim]

Thanks for making the changes 🙇
Quote in composer is showing up everywhere now, could we limit it just to the composer?

[katinthehatsite]

I am also seeing the same behavior as @bcotrim , I think it would make sense to clean that up as it does not seem to be necessary to have it on the buttons and other controls

[shaunandrews]

Good catch; should be fixed now.

[bcotrim]

LGTM 👍