fix(feishu): render markdown tables via post+md, not text downgrade

[JasonFang1993]

Summary

Fixes #52786 and fixes #23938, closing the duplicate cluster around #31056.

_build_outbound_payload in plugins/platforms/feishu/adapter.py was force-downgrading any message containing a markdown pipe table to msg_type=text, so Feishu readers rendered the raw pipe-and-dash source instead of a table. Empirically current Feishu clients render markdown tables inside post-type md elements natively, so the downgrade branch had to go.

Changes

1. _MARKDOWN_HINT_RE now also matches a pipe-table header + separator pair, so a table-only message is recognised as "has markdown" and takes the post path.
2. _build_outbound_payload no longer special-cases _MARKDOWN_TABLE_RE before the hint check. Table content now flows through the same _build_markdown_post_payload path as every other markdown structure (headings, lists, code, bold, links, etc.).

_MARKDOWN_TABLE_RE itself is retained as a module-level constant for backwards compatibility with external callers.

Tests

New file: tests/gateway/test_feishu_table_markdown.py (4 regression tests).

• test_markdown_table_uses_post_not_text — pure-table content → post, with table text inside an md element (issue Feishu adapter incorrectly downgrades markdown tables to plain text #52786 scenario)
• test_table_combined_with_other_markdown_does_not_downgrade — prose + table + prose message keeps its surrounding markdown
• test_existing_markdown_heading_still_uses_post — heading path unchanged
• test_plain_text_without_markdown_still_uses_text — negative control

The new tests use the projects tests/gateway/_plugin_adapter_loader.load_plugin_adapter() helper, as required by the conftest plugin-adapter anti-pattern guard.

Verification

pytest tests/gateway/test_feishu.py tests/gateway/test_feishu_table_markdown.py

→ 209 passed (205 existing + 4 new), three consecutive runs.

Rollback

git reset --hard 44ddc552f5e054759a6970af8997ea588a9d81c9

restores upstream main without the new test file.

Related

• Issue [Bug]: Feishu adapter strips all Markdown formatting when message contains a table #23938 (older sibling)
• PR fix(feishu): render markdown tables correctly via post+md instead of downgrading to text #31056 (earlier attempt)
• Other open feishu-markdown-table duplicates

[JasonFang1993]

Hi! Submitting this as a fix for the table-downgrade branch in
_build_outbound_payload.

A quick note on where this PR sits in the existing cluster of "feishu
markdown table" reports:

• Closes Feishu adapter incorrectly downgrades markdown tables to plain text #52786 (most recent report — clean reproduction script and
  message_id cited in the thread)
• Also fixes the older siblings: [Bug]: Feishu adapter strips all Markdown formatting when message contains a table #23938, fix(feishu): render markdown tables correctly via post+md instead of downgrading to text #31056, and any other
  table-rendering open duplicates

I deliberately did not touch any of the in-flight
feat/feishu-markdown-* PRs (#52046 etc.) because the right place for
this fix is the post + md payload-builder path, not the
interactive-card path those PRs pivot toward — the two are not
equivalent, and trying to merge them would create a behaviour split
between "card-rendering clients" and "post-rendering clients" that
would be painful to undo later. Happy to coordinate if a maintainer
prefers the card route, but my read of #52786's reproduction (text +
table on the same line) is that the post path is the lowest-risk
fix.

Quick verification locally (with this branch):

$ pytest tests/gateway/test_feishu.py          tests/gateway/test_feishu_table_markdown.py -q
209 passed, 2 warnings in ~12s

(205 pre-existing + 4 new regression tests.)

Happy to iterate on the test surface or refactor any of the
inline re.compile blocks into a more readable shape — just point.

[alt-glitch]

This was generated by AI during triage.

Duplicate of #52790 — same code site (_build_outbound_payload in plugins/platforms/feishu/adapter.py) and same mechanism: remove the _MARKDOWN_TABLE_RE text-downgrade and add a pipe-table pattern to _MARKDOWN_HINT_RE so table-only messages still take the post+md path. #52790 (also "Closes #52786") is the earliest open PR with this exact approach. Related competing fixes in the Feishu-table cluster use a different mechanism: #57024 (guard-delete only), #31056 (downgrade-removal only), #53453 (adds a streaming text→post edit fallback). Anchor issue: #9549.

[teknium1]

Merged via #68121 — your commit was cherry-picked onto current main with your authorship preserved in git log. Your implementation was the cleanest of the 9 competing fixes (current plugin path, hint-regex extension, regression tests using the required loader helper) and served as the base of the salvage. Thanks!