[roboeve]

Summary

Fixes #956. Bulleted and numbered lists typed in Slack's message composer now parse to mdast list nodes, including nested items.

The special-mentions half of #956 was fixed in #960. This PR covers the list half, which still reproduces on main: Slack flattens composer lists in event.text to lines starting with • or ◦, which are not markdown list syntax, so the issue's payload parses to a single paragraph. With this change it gives:

nodes   : ["paragraph","list","paragraph"]
markdown: "Steps:\n\n* one\n* two\n  * nested\n\n@here and @devs\n"

Approach

The list structure exists only in event.blocks, as rich_text_list elements with style, indent, and offset. When a message's blocks contain a list and every non-table block is rich_text, the new richTextBody (src/rich-text.ts) renders the blocks to the same mrkdwn dialect event.text uses, with markdown list markers. content() and resolvedContent() use that body instead of event.text on the text path, so mention resolution, the format converter, and table handling are unchanged. Every other message, including the layout-block bodies from #1062, keeps its current path.

• Nested lists arrive as sibling rich_text_list elements with a higher indent. Each item is indented to its parent's content column, so - and 10. parents both nest correctly, and ordered lists continue from offset across a nested list.
• Inline styles share markers across consecutive elements: bold make , bold italic this, bold work renders as *make _this_ work*. A style change that mrkdwn cannot express (bold starting mid-word, or a closing marker pressed against an opening one) keeps the text and drops only that formatting, instead of leaving stray * in the output.
• Styles on links, mentions, and emoji are kept, and @here inside inline code stays literal, matching how event.text parses.
• Block elements carry only IDs, so labels for <!subteam^…|@handle> and <#C…|name> are copied from event.text.
• Trailing newlines are trimmed with a loop. The /\n+$/ regex flagged by CodeQL took about 39 seconds on 200,000 newlines in the new test.
• Link labels in rich text are now entity-escaped, so a > in a label (including in table cells, which share blocktext) no longer ends the link early.

SlackMessageBlock["style"] gains bold, italic, and strike. It stays an object type, so existing reads of block.style?.code still compile; a type test guards this.

message.text follows the core toPlainText output for lists, so it now reads one\ntwo instead of • one\n• two.

Test plan

• src/rich-text.test.ts: renderer logic, checked as mrkdwn and as markdown after the adapter's format converter (nesting columns, offsets, multi-line items, style nesting and mid-word changes, punctuation, line breaks, code, links, mention labels, quotes and code blocks, gating, and linear-time trimming). The trimming and link-label tests fail against the previous implementation.
• src/rich-text.test-d.ts: the style type stays an object, and richTextBody's signature.
• src/index.test.ts: the issue's payload through parseMessage and the async parser, user mention resolution and bot-mention detection inside list items, a table next to a list, the event.text fallback, and a > in a table cell link label. The list tests fail on main.
• vitest run in packages/adapter-slack (963 tests, no type errors), tsc --noEmit, ultracite check, pnpm knip, and pnpm konsistent pass. The full packages/integration-tests suite passes (63 files, 1,425 tests).
• Smoke test against the built packages: signed event_callback requests through chat.webhooks.slack with a memory state reach onDirectMessage and onNewMention with the expected list markdown, and a message without a list keeps event.text.

The branch merged main to resolve conflicts with #1062. The first implementation is backed out in two commits before the merge and reapplied after it.

Checklist

• All commits are signed and verified
• All commits are signed off for the DCO (git commit -s)
• pnpm validate passes
• Changeset added (or N/A — see CONTRIBUTING.md)
• Documentation updated (or N/A)

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[roboeve]

CI on fdb41d9 failed on one test from this PR: trims long runs of trailing newlines in linear time took 2,046 ms against a 1,000 ms budget on Node 24 (vitest with coverage). The time went to building 400k inline runs for the quote, which is linear work, not the trim the test was written to check.

0d627ed switches the test input to a rich_text_preformatted element, which renders in one pass, so the trim over the whole body is the only work that grows with the input. Locally it now runs in 3 ms with coverage. With the old /\\n+$/ trim put back temporarily, the same test takes about 29 s and fails, so it still catches the regression. Product code is unchanged. All 22 tests in rich-text.test.ts pass and ultracite check is clean. New CI is pending.