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Arc 0.51.85 — Review before replying
Published October 25, 2026 · Windows x64 development release.
This release includes changes 0.51.84 and 0.51.85 since public 0.51.83.
Take another look before answering
Choose High or Ultra and open the thinking-level menu. Review before replying is enabled by default and can be switched off there.
- High: one review of the final draft against your request and the available evidence.
- Ultra: up to two reviews, including a second look after a correction when needed.
- One bounded correction: checks look for missing requirements, contradictions, calculation mistakes and unsupported claims. A good draft can remain unchanged.
- Visible progress: brief review/check/correction counters explain the result without presenting a model review as verified correctness.
- The same selected model: reviews run serially, with no extra reviewer model and no executable tools. They cannot repeat posts, send emails, modify files or expand permissions.
- Existing checks stay in charge: file, source, screenshot and completion checks still determine whether the requested task was completed. A short outcome checklist also guides eligible work calls.
Instant, Medium and voice retain their existing response paths. Extra review calls consume time and tokens; they do not increase the context window or guarantee a correct answer. Reviews have bounded deadlines and preserve the usable draft when a review fails or cannot fit. Large files and incomplete tasks still need their own real checks.
Music has moved out of Arc
As requested, 0.51.84 removes Arc's standalone YouTube Music player, saved-playlist panel and voice/text music playback commands, along with their music-only resolver and playback services. Existing playlist metadata is left untouched but is no longer read by Arc.
YouTube search, captions, transcripts, video research and screen/audio context remain available. TwinYou Music is a separate app and is unchanged. Earlier music release notes remain in the version history as historical records.
Validation and limits
For this publication, all 23 focused answer-review and signed-update tests passed, and packaged-runtime checks confirmed version 0.51.85, matching implementation files, a two-check correction and preference persistence. The installer matches the original successful October 21 build and packaging record.
The earlier Arc Focus run passed five neutral fixtures covering arithmetic, requested formatting, unsupported test-success claims, an already-correct answer and an actual agent conversation. This is not a broad accuracy or speed benchmark.
The earlier full suite recorded 3,851 passes, nine failures and ten skips. All nine original failing cases subsequently passed focused reruns, but the complete suite was not rerun to a clean result; a larger retry also hit the test runner's heap limit. These scopes overlap and must not be added together. No fresh GPU/model benchmark or installation over the user's personal profile was performed for this publication.
Download and verification
- Windows installer — 334,602,221 bytes (about 319 MiB).
- Website download · Version history · Review setup and limits.
- SHA-256:
097fae952d87f028ee5151174cad75dd22447d0c6f52f87af62062913aab45d5.
The installer is not Windows Authenticode-signed. Signed Arc updater metadata and SHA-512 download verification are separate integrity checks. No VirusTotal result is claimed for this exact installer. Model weights remain separate downloads; normal updates preserve models, conversations and settings.