feat(apollo-react): add the Wind chat composer

[BenGSchulz]

Summary

Fifth and last PR of the Wind chat renderer stack (MST-16566). The Wind composer placeholder from R-1 is replaced by apollo-wind's ChatComposer, wired to the service as Material's input is.

• Draft: the composer follows the service prompt (getPrompt at mount, SetPrompt after) and writes edits back with setPrompt; an empty draft clears it, as in Material. SetInputFocused focuses the field.
• Send:
  • Enter sends and Shift+Enter starts a new line; the primitive leaves IME composition alone.
  • Sending goes through the service Request intercept with the prompt text and the attachments, then clears the draft and the attachments.
  • Focus returns to the field after a send from the button.
  • Sending is held back during the initial skeleton load and while an attachment is still loading.
  • A parity test checks that the Request payload from Wind matches Material's.
• Stop: while a reply is awaited or streams, the send button stops it, unless disabledFeatures.stopResponse is set, in which case it stays a disabled send button and Enter does not send. Same as Material. The button stays filled in both states (variant="default"), as Material's does; the primitive's ghost stop button faded its fill out on every send and read as a flicker.
• Attachments (chips sized as Material's: 30px tall, at most half the message, 8px apart, name truncated with the full name as a tooltip only when cut off, on messages and in the composer; a sent message's attachment row is capped to the message so it scrolls inside the panel):
  • They come in through the attach button, a panel-wide DropzoneOverlay drop, and paste anywhere on the panel, checked against allowedAttachments: MIME types and their extensions, max size, and the max count minus what is already attached (maxCount: 0 means no limit, as in Material).
  • Paste is handled by Wind with apollo-wind's validateFiles: it takes over the paste only when a file passes, so text pasted alongside a refused file still lands, and the refused file is named in the error.
  • While the panel cannot take files (attachments disabled, no composer, chat closing), a file dropped on it is still caught so the browser does not open it in the tab.
  • Removing a chip while the host uploads it publishes SetAttachments with it in removed and drops it from the draft; finishing the upload never brings it back, so the remove button stays available while uploading.
  • Chips use the file type icons from the message list, show as uploading while the service marks them loading, and can be removed.
  • The attach button lists the limits in a tooltip and to screen readers, as Material's does.
  • Hidden, and drops ignored, when disabledFeatures.attachments is set.
  • Chip sizing: on messages the cap is calc(50cqw - 4px) against the message content (an @container), not a percentage of the row. A user message's row is end-aligned and sizes itself to its chips, so a percentage of it squeezed a lone chip to half its own width. With Material's 8px gap, two capped chips fill the message exactly; the composer row uses the same 8px gap (overriding the primitive's 12px).
  • Alignment: a user message's row sits at the message's trailing edge while its chips fit (justify-end-safe) and starts from the leading edge once it overflows, so the whole row stays reachable by scrolling. Reply rows stay start-aligned.
• Errors and footer:
  • The service error (error or warn) shows above the field as ChatComposerError (role="alert"), rendered as markdown like Material's, and dismissing it clears the error and keeps focus in the field.
  • The footer disclaimer comes from the shared useChatLabels at 10px, as in Material, hidden with disabledFeatures.footer.
• Compact and read-only:
  • spacing.compactMode sets the composer's compact density, and spacing.promptBox sets the textarea rows.
  • Read-only hides the composer, as R-1 already did and as Material does.

Hoisted into src/chat/headless

Helper	What it carries	Material change
hooks/use-attachment-intake.ts: useAttachmentIntake, getAcceptedFileTypes	Material's dropzone rules and messages: one file at a time when multiple is off, the whole batch refused when over maxCount, oversized and wrongly typed files named, the rest parsed and attached, the error cleared when nothing was refused. Takes neutral rejection reasons, so both react-dropzone and apollo-wind's checks feed it	dropzone.tsx maps react-dropzone codes onto it (its own handling removed)
hooks/use-composer-send.ts: useComposerSend	In-flight state, whether stop is allowed, send (ending dictation first) and stop	chat-input.tsx submit uses it
hooks/use-attachment-intake.ts: checkAttachmentFiles	Picked files checked as the drop targets check them: type by MIME or extension, size, then the count left	chat-input-actions.tsx attach button now validates types, size and count through it and the intake hook, like the dropzone (its size message is now the dropzone's)
hooks/use-attachment-limits.ts: useAttachmentLimits	The attach limits text (max files, max size, allowed types)	chat-input-actions.tsx tooltip and screen-reader description

Storybook

pnpm storybook:design, then Apollo React / Chat / Playground, Compare renderers:

• Attachments (chips sized as Material's: 30px tall, at most half the message, 8px apart, name truncated with the full name as a tooltip only when cut off, on messages and in the composer; a sent message's attachment row is capped to the message so it scrolls inside the panel): a user turn with files, then a draft with an attachment placed in both composers through setPrompt. Attach more with the button, by dropping files on the panel, or by pasting.
• Error and Warning: the alert above the composer, with markdown and a dismiss button.
• autoReply echo or stream: send from either composer. The message mirrors to the other chat and both reply. Stop while streaming, or turn on disableStopResponse to see a disabled send button instead.
• compactMode: the compact composer.
• disableAttachments, disableFooter, inputPlaceholder and footerDisclaimer.

Tests

• vitest --run src/chat src/material/components/ap-chat src/material/components/ap-tool-call: 49 files, 280 tests pass. New tests cover:
  • the intake rules: accepted plus named rejections, the whole batch refused when over the count, one file at a time, the accept list;
  • the composer:
    • Enter and Shift+Enter;
    • focus after send;
    • following the service prompt;
    • stop, and stop disabled;
    • the error alert as markdown, with warn and dismiss;
    • picked files sent with the prompt;
    • an oversized file named;
    • drop and paste on the panel;
    • attachments disabled;
    • compact and the footer;
    • chips capped against the message width with an 8px gap, in messages and the composer;
    • a user message's row end-aligned, a reply's not;
  • the Request payload parity test against Material.
• tsc --noEmit: clean.
• Known gap (W-10): apollo-wind's DropzoneOverlay takes a single hint string, so Wind's drop overlay cannot list the max count, size and types as Material's does. Composer chips also take no title or tooltip from the primitive, so the truncation tooltip is a native title.
• biome check on touched files: clean.
• New strings, in en.json only: input.label ("Message", the field's accessible name) and input.error.dismiss ("Dismiss"). Everything else reuses Material's ids with Material's source messages.

Stack

1. R-1 Wind shell: feat(apollo-react): add the Wind chat renderer shell #1371
2. R-2 message list: feat(apollo-react): add the Wind chat message list #1372
3. R-3 markdown renderer: feat(apollo-react): add the Wind chat markdown renderer #1375
4. R-4 tool-call and tree renderers: feat(apollo-react): add the Wind chat tool-call and tree renderers #1376
5. R-5 composer: this PR
6. R-6 first run, suggestions and thinking state: feat(apollo-react): add the Wind chat first run, suggestions and thinking state #1396
7. R-7 history and settings: feat(apollo-react): add the Wind chat history and settings panels #1397
8. R-8 CSS delivery and docs: feat(apollo-react): document the Wind chat setup and its delivery #1399

Jira: MST-16566

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Dependency License Review

• ✅ 1947 package(s) scanned
• ✅ No license issues found
• ⚠️ 2 package(s) excluded (see details below)

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License	Packages
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BSD-2-Clause	23
BlueOak-1.0.0	8
MPL-2.0	4
MIT-0	3
CC0-1.0	3
MIT OR Apache-2.0	2
(MIT OR Apache-2.0)	2
Unlicense	2
LGPL-3.0-or-later	1
Python-2.0	1
CC-BY-4.0	1
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khroma	2.1.0	Unknown	MIT per GitHub repo, missing license field in package.json

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📊 Coverage + size by package

Per-package coverage and bundle size on this PR. New-line coverage = of the source lines this PR adds or changes, the % hit by tests.

Package	Coverage	New-line coverage	Packed (gzip)	Unpacked	vs main
@uipath/apollo-core	—	—	42.02 MB	50.17 MB	±0
@uipath/apollo-react	56.1%	93.2% (179/192)	8.02 MB	31.61 MB	+35.1 KB
@uipath/apollo-ui-icons	—	—	2.86 MB	6.97 MB	±0
@uipath/apollo-vertex	—	—	—	—	—
@uipath/apollo-wind	—	—	785.2 KB	4.55 MB	+18 B
@uipath/ap-chat	85.8%	—	40.37 MB	45.58 MB	+2.0 KB

_{"Coverage" is each package's own coverage.include scope (e.g. apollo-core instruments only scripts/). "Packed"/"Unpacked" come from npm pack --dry-run and only cover built packages — "—" means not measured this run (package not affected / not built). "vs main" is the packed (gzipped) delta against the last successful main build (the package-sizes artifact from the Release workflow); "—" there means no main baseline was available this run. The baseline is main's latest build, not this PR's exact merge-base, so it includes any drift since the branch diverged. Packages with no vitest config are omitted.}

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[CalinaCristian]

One functionality discrepancy in the storybook for composer vs material:

Screen.Recording.2026-10-20.at.3.40.23.AM.mov

Screen.Recording.2026-10-20.at.3.41.03.AM.mov

In material, we don't allow same attachment twice.
Also, when in compact mode I see no difference for the wind component in the attachments section.

[BenGSchulz]

One functionality discrepancy in the storybook for composer vs material:

In material, we don't allow same attachment twice. Also, when in compact mode I see no difference for the wind component in the attachments section.

Thanks for catching that. The gaps in compact mode are known and will be addressed via #1403. I will make sure to cover the duplicate attachments in the follow-up to those.