Teams card_to_adaptive_card divider renders zero-height (empty Container with separator: True)

[patrick-chinchill]

Summary

card_to_adaptive_card converts a divider child into an empty Container with separator: True. Microsoft Teams renders this container at zero height because it has no items, so the separator line is effectively invisible and does not span the card width.

Location

src/chat_sdk/adapters/teams/cards.py, _convert_child_to_adaptive (~L119):

if child_type == "divider":
    return {
        "elements": [{"type": "Container", "separator": True, "items": []}],
        "actions": [],
    }

Expected

The divider should render as a full-width separator line. One option is to hoist separator: True onto the next sibling element instead of emitting an empty container — e.g. during post-processing of the body array, pop any empty-container divider and set separator: True on the following element.

Repro

from chat_sdk.cards import Card, Divider, TextBlock
from chat_sdk.adapters.teams.cards import card_to_adaptive_card

card = Card(children=[TextBlock("above"), Divider(), TextBlock("below")])
payload = card_to_adaptive_card(card)
# Send payload to Teams: no visible divider between "above" and "below".

Workaround (in consuming code)

Wrap card_to_adaptive_card and post-process its output to hoist separators onto the next non-divider element in body, then drop the empty container.

---

Upstream TS parity

Vercel TS (vercel/chat) has the same bug in packages/adapter-teams/src/cards.ts:

function convertDividerToElement(_element: DividerElement): Container {
  return new Container().withSeparator(true);
}

Per UPSTREAM_SYNC.md ("upstream behavior is input not source of truth"), this is a valid divergence: fix in the Python port now rather than waiting for upstream. Document the divergence in UPSTREAM_SYNC.md under Teams-adapter divergences, and add a regression test. A courtesy issue can be filed on vercel/chat suggesting the same fix, but it should not block this.

[patrick-chinchill]

Closing — this was shipped in v0.4.26.1. See CHANGELOG entry referencing issue #45. Issue was left open by oversight.