fix: allow redact-power users to end polls (MSC3381)

[Quantumheart]

Summary

I am working on a Matrix client called Kohera. I am currently, working through the polling spec 3381 and found that the power level redaction is not respected for moderators.

Changes

• add !room.canRedact
• add test "endPoll: creator may end, non-creator without redact power may not, redact power may end"

[cursor]

PR Summary

Low Risk
Small authorization fix in poll MSC code with matching tests; behavior now matches spec and receive-side validation.

Overview
endPoll no longer requires the current user to be the poll creator; users with room redact power (room.canRedact) may end someone else’s poll, matching MSC3381 and the existing _getEndPollEvent rules for accepting m.poll.end events.

Documentation on endPoll was added to describe who may end a poll. A test covers rejection for non-creators without redact power, success after granting redact power, and the creator path.

^{Reviewed by Cursor Bugbot for commit 6c5ce3e. Bugbot is set up for automated code reviews on this repo. Configure here.}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.66%. Comparing base (53a6a79) to head (6c5ce3e).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2413      +/-   ##
==========================================
+ Coverage   59.62%   59.66%   +0.03%     
==========================================
  Files         161      161              
  Lines       20329    20329              
==========================================
+ Hits        12121    12129       +8     
+ Misses       8208     8200       -8     

Files with missing lines	Coverage Δ
...xtensions/msc_3381_polls/poll_event_extension.dart	83.60% <100.00%> (+13.11%)	⬆️

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[krille-chan]

From the MSC:

If a m.poll.end event is received from someone other than the poll creator or user with permission to redact other's messages in the room, the event must be ignored by clients due to being invalid.

So you are right :) I also checked that we are already correctly parsing it manually, just this check was missing. Thank you very much

[krille-chan]

@Quantumheart you need to sign your commit and make sure you accepted the CLA (the cla bot may be prompted once you signed your commit)

[CLAassistant]

All committers have signed the CLA.

[cursor]

Cursor Bugbot has reviewed your changes using high effort and found 1 potential issue.

^{Bugbot Autofix is ON, but it could not run because the branch was deleted or merged before autofix could start.}

^{Reviewed by Cursor Bugbot for commit 52d19d8. Configure here.}

[Quantumheart]

Resolved in 6c5ce3e — the denial-case expectLater is now awaited so the matcher completes before the redact-power injection. Test passes locally.

[Quantumheart]

@krille-chan are you able to approve the workflow? Thanks in advance.