fix(llc): keep reaction group while its count stays positive

[xsahil03x]

Summary

Message dropped an entire ReactionGroup in two places when a group's summed scores were non-positive, even though its count was still positive — so count-based reaction UIs lost other users' reactions:

1. deleteMyReaction (optimistic delete) kept a group only when count > 0 && sumScores > 0. During an optimistic delete, a group whose scores net to zero/negative vanished until the next server event re-hydrated it.
2. _reactionGroupsReadValue (legacy-payload parse fallback that synthesizes groups from the old reaction_counts/reaction_scores maps) discarded a group when sumScores == 0, dropping a still-populated group at parse time. (Flagged in review by @renefloor.)

Root cause / backend alignment

The backend derives reaction groups from the reactions table via count(type) / sum(score) grouped by (message_id, type). A group exists iff at least one reaction row remains (count >= 1); sum(score) is an independent aggregate that may legitimately be 0 or negative and never gates whether the group exists.

Both call sites now gate purely on the count.

Changes

• deleteMyReaction: retain the group while updatedCount > 0.
• _reactionGroupsReadValue: retain the group while count > 0 (guard count <= 0 so a malformed negative count can't build an invalid group).
• Regression tests: realistic delete-path fixture (own score: 1, other score: -1 → net zero, then negative after delete) and a legacy-payload test covering zero and negative score totals.
• stream_chat CHANGELOG entries.

Testing

flutter test test/src/core/models/message_test.dart test/src/core/models/message_reaction_helper_test.dart — all pass.

Fixes FLU-663

🤖 Generated with Claude Code

[coderabbitai]

📝 Walkthrough

Walkthrough

Message now retains reaction groups when their count is positive, even when the aggregate score is zero or negative. This applies to legacy payload parsing and deleteMyReaction. Regression tests and a changelog entry document the behavior.

Changes

Reaction group retention

Layer / File(s)	Summary
Retain legacy reaction groups packages/stream_chat/lib/src/core/models/message.dart, packages/stream_chat/test/src/core/models/message_test.dart	Legacy reaction parsing now skips groups only when their count is nonpositive. The regression test covers positive counts with zero and negative summed scores.
Update reaction deletion retention packages/stream_chat/lib/src/core/models/message.dart, packages/stream_chat/test/src/core/models/message_reaction_helper_test.dart, packages/stream_chat/CHANGELOG.md	deleteMyReaction retains groups with a positive remaining count regardless of aggregate score. The regression test and changelog document the fix.

Estimated code review effort: 2 (Simple) | ~10 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: preserving a reaction group while its count remains positive.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch sahil/flu-663-fix-reaction-group-delete

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 72.86%. Comparing base (401ab01) to head (e0d821c).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #2858   +/-   ##
=======================================
  Coverage   72.86%   72.86%           
=======================================
  Files         429      429           
  Lines       27698    27698           
=======================================
  Hits        20183    20183           
  Misses       7515     7515           

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@packages/stream_chat/lib/src/core/models/message.dart`:
- Around line 175-176: Update the count guard in the reaction-group construction
logic to skip all non-positive legacy counts by changing the zero-only check to
a less-than-or-equal check. Retain groups only when count is positive, while
preserving the existing handling of score values.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro Plus

Run ID: 3e01010c-fcbd-44f3-8a28-f6759592791c

📥 Commits

Reviewing files that changed from the base of the PR and between 29f7508 and 668ed31.

📒 Files selected for processing (3)

• packages/stream_chat/CHANGELOG.md
• packages/stream_chat/lib/src/core/models/message.dart
• packages/stream_chat/test/src/core/models/message_test.dart