feat(platform): improve chat markdown rendering and scroll behavior

[larryro]

Summary

• Improve markdown remending to strip empty formatting markers and close open formatting inside incomplete table cells
• Simplify chat scroll logic and keep chat scrolled to bottom during streaming when user is already at the bottom
• Add tests for markdown remending utility

Test plan

• Verify streaming chat messages render without stray asterisks or formatting artifacts
• Confirm chat auto-scrolls during streaming when scrolled to bottom
• Confirm chat does not auto-scroll when user has scrolled up
• Run remend-markdown tests pass

Summary by CodeRabbit

• Bug Fixes

  • Improved markdown formatting by better handling empty formatting markers in bold, italic, and strikethrough syntax.
  • Enhanced formatting preservation within table cells to ensure proper closure and well-formed table structure.

• Tests

  • Added comprehensive test coverage for markdown formatting completeness scenarios, including empty marker stripping and in-table formatting preservation.

[greptile-apps]

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[coderabbitai]

📝 Walkthrough

Walkthrough

This pull request modifies three files in the chat feature module: it removes explanatory comments from the chat interface's scroll coordination logic without changing functional behavior; adds comprehensive test cases for markdown formatting edge cases including empty formatting markers and formatting within table cells; and refactors the markdown remending logic to close formatting tokens (bold, italic, strikethrough) inside table cells rather than after the row, updating the remendTable function signature to return an object with consumed status instead of just text.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Possibly related PRs

• Support <details> elements in chat markdown #840: Modifies both chat-interface.tsx's scroll behavior and remend-markdown.ts formatting closure logic in coordinated changes.
• feat(platform): simplify chat auto-scroll and fix streaming markdown flicker #830: Coordinates changes to chat auto-scroll behavior in chat-interface.tsx with related modifications to remend-markdown.ts implementation and tests.
• feat(platform): persistent chat, scroll-intent, typewriter, and system message tags #836: Directly related as this PR removes the scroll-intent pattern implementation and comments that were introduced in PR#836.

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the two main changes: markdown rendering improvements (remending) and scroll behavior simplification, matching the file modifications across chat components and utilities.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch feat/chat-markdown-improvements

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[coderabbitai]

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

services/platform/app/features/chat/components/chat-interface.tsx (1)

224-229: ⚠️ Potential issue | 🟠 Major

Clear auto-follow intent when the user scrolls away from bottom.

scrollingToBottomBehaviorRef is only reset when isAtBottom() is true, so after handleSendMessage sets 'smooth', manual upward scrolling can still get overridden by subsequent content mutations. This violates the “no auto-scroll when user scrolled up” requirement.

Proposed fix

@@
-    const onScroll = () => {
-      if (scrollingToBottomBehaviorRef.current && isAtBottom()) {
-        scrollingToBottomBehaviorRef.current = null;
-      }
-      setShowScrollButton(!isAtBottom());
-    };
+    const onScroll = () => {
+      const atBottom = isAtBottom();
+      // Stop intentional auto-follow as soon as user is no longer at bottom.
+      if (scrollingToBottomBehaviorRef.current && !atBottom) {
+        scrollingToBottomBehaviorRef.current = null;
+      }
+      setShowScrollButton(!atBottom);
+    };

Also applies to: 315-315

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@services/platform/app/features/chat/components/chat-interface.tsx` around
lines 224 - 229, The current onScroll leaves
scrollingToBottomBehaviorRef.current set when the user manually scrolls up, so
auto-follow can still trigger; update onScroll to clear
scrollingToBottomBehaviorRef.current whenever isAtBottom() is false (i.e., user
scrolled away) and still call setShowScrollButton(!isAtBottom()); apply the same
change to the other scroll handler referenced around line 315 so any manual
scroll clears the auto-follow intent set by
handleSendMessage/scrollingToBottomBehaviorRef.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Outside diff comments:
In `@services/platform/app/features/chat/components/chat-interface.tsx`:
- Around line 224-229: The current onScroll leaves
scrollingToBottomBehaviorRef.current set when the user manually scrolls up, so
auto-follow can still trigger; update onScroll to clear
scrollingToBottomBehaviorRef.current whenever isAtBottom() is false (i.e., user
scrolled away) and still call setShowScrollButton(!isAtBottom()); apply the same
change to the other scroll handler referenced around line 315 so any manual
scroll clears the auto-follow intent set by
handleSendMessage/scrollingToBottomBehaviorRef.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

Plan: Pro

Run ID: da926113-31c7-4b28-a3cb-e7613db4d978

📥 Commits

Reviewing files that changed from the base of the PR and between 8af8457 and b60eb77.

📒 Files selected for processing (3)

• services/platform/app/features/chat/components/chat-interface.tsx
• services/platform/app/features/chat/utils/__tests__/remend-markdown.test.ts
• services/platform/app/features/chat/utils/remend-markdown.ts