Preserve text_format through HttpStream's intermediate and final activities

[Copilot]

Summary

Ports microsoft/teams.ts#762 and its follow-up #784 to the Python SDK.

On every flush(), HttpStream rebuilds the outbound typing chunk and forwards the last emitted message's attachments, entities, suggested actions, and channel data ("last message wins" via self._final_activity) — but not text_format. So stream.emit(MessageActivityInput(text=...).with_text_format("extendedmarkdown")) was dropped from every intermediate chunk, and streamed Extended Markdown (task lists, strikethrough) rendered as plain markdown until the message closed.

The final message and timeout fallback (_send_final) already preserved text_format, since they reuse the real _final_activity object rather than rebuilding a copy (unlike TS). Only the streamed chunks needed fixing.

Changes

• Add text_format + a with_text_format() builder to _TypingBase (shared by TypingActivity / TypingActivityInput), mirroring MessageActivityInput.
• HttpStream._flush() applies the last emitted message's text_format to the combined streamed-text chunk (last-message-wins).
• Informative updates keep their own text_format. _flush() previously overwrote each informative update's format with _final_activity.text_format; it now leaves the update's own value intact (_final_activity isn't even set when informative updates are sent).
• update() gains an optional text_format. StreamerProtocol.update / HttpStream.update now accept text_format; None → Teams default (markdown), an explicit value → that format. Previously the only way to format an informative update was to hand-build a typing activity and emit() it.
• examples/stream: refresh the extended-markdown scenario and demo the new update(text, "markdown") overload.
• Unit tests for text_format on typing activities, its propagation across streamed chunks / final message / timeout fallback, informative-update format independence (red/green against the old overwrite), and the update() overload.

Testing

• ruff format --check, ruff check, pyright, pytest packages (1107 passed) — all pass.
• Verified live in Teams: streaming a message with text_format="extendedmarkdown" renders task lists and strikethrough on each intermediate chunk.

Created from a Microsoft Teams conversation.

[Kavin (singhk97)]

After fix demo:

after-fix-cs.mp4

[Copilot]

Pull request overview

This PR updates the Python streaming implementation (HttpStream) so text_format is preserved consistently across intermediate typing chunks, informative updates, and the final message—aligning behavior with the TypeScript SDK and preventing extended markdown streams from rendering incorrectly mid-stream.

Changes:

• Add text_format support (and a with_text_format() builder) to typing activities via _TypingBase.
• Propagate the last-emitted message’s text_format to combined streamed typing chunks, while ensuring informative updates keep their own text_format.
• Extend stream.update() (protocol + implementation) to accept an optional text_format, and add/refresh unit tests and the examples/stream extended-markdown scenario.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
packages/apps/tests/test_http_stream.py	Adds tests covering text_format propagation for intermediate chunks, final send, timeout fallback, and informative updates.
packages/apps/src/microsoft_teams/apps/plugins/streamer.py	Extends StreamerProtocol.update() to accept optional text_format and documents the behavior.
packages/apps/src/microsoft_teams/apps/http_stream.py	Implements text_format preservation in _flush() and adds update(text, text_format) support for informative updates.
packages/api/tests/unit/test_typing.py	Adds unit tests for typing activity text_format builder and default behavior.
packages/api/src/microsoft_teams/api/activities/typing.py	Adds text_format field + with_text_format() builder to typing activity models.
examples/stream/src/main.py	Adds an extended-markdown streaming demo showcasing per-chunk text_format.
examples/stream/README.md	Documents the new extended-markdown scenario and the update(text, \"markdown\") overload.

Suppressed comments (1)

packages/apps/src/microsoft_teams/apps/http_stream.py:346

• In _flush(), use an explicit is not None check when deciding whether to apply text_format to the combined typing chunk. This keeps the logic aligned with the Optional type and the public contract (omit vs explicit).

                to_send = TypingActivityInput(text=self._text)
                if text_format:
                    to_send.with_text_format(text_format)
                await self._send_activity(to_send)

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[Kavin (singhk97)]

I attest that I have verified