Hardens .mosaicsync profile import by rejecting excessively large files before their contents are loaded into memory, with a localized error across all supported languages. Adds a final HTTP(S)-only safety check to shortcut navigation paths as defense-in-depth on top of existing profile/Sync/state validation. Removes obsolete historical migration code and a superseded Frequently Visited responsive CSS rule, and expands adversarial regression coverage for profile security, URL validation and concurrent edits. No new permissions, Sync/profile format changes, telemetry, remote code or CSP relaxation.

MosaicSync 1.26.17.3 includes the full improvements accumulated since 1.26.12: automatic favicon recovery and safety hardening, Frequently Visited improvements and cross-Space duplicate prevention, Sync self-healing improvements, independent Light/Dark wallpaper darkness, profile/export boundary clarifications, and expanded regression coverage. This revision also fixes a localized Settings layout issue where longer translations such as French could overlap the “Clear Sync copy” action. No new required permissions, telemetry, remote code, CSP relaxation, or profile/Sync format change.

Changes since the last published 1.26.12 source

Reworked Automatic site icons so new iconless shortcuts can recover favicons automatically without requiring a first visit.
Hardened Chromium native favicon fallback and improved bounded favicon/image handling.
Improved Frequently Visited with stable first-frame rendering, cross-Space duplicate filtering, drag-to-grid and device-local site-family hiding.
Fixed Light/Dark wallpaper darkness leakage. Separate Light and Dark wallpapers now keep independent darkness values, and automatic/system appearance switching changes the wallpaper and its matching darkness together. Existing users preserve the darkness of the appearance active during migration while the opposite appearance starts at 0%.
Strengthened Sync self-healing so locally delivered synchronized changes can recover after a missed change event without requiring a browser restart.
No new required permissions, remote code, telemetry or CSP relaxation. The two new darkness settings are backward-compatible additions and require no Sync/profile format-version bump.

Reworked Automatic site icons so new iconless shortcuts can recover favicons automatically without requiring a first visit. Website Access remains optional and permission requests still originate from explicit user gestures.
Consolidated favicon recovery across Firefox and Chromium, including Personal and Work Spaces, while keeping automatically learned/browser-native favicon pixels out of ordinary browser Sync.
Hardened Chromium native favicon fallback so a failed placeholder probe cannot store Chrome's generic globe as permanent site artwork.
Improved favicon compatibility and preserved bounded raster/SVG safety.
Improved Frequently Visited with stable first-frame rendering, drag-to-grid creation and device-local site-family hiding.
Frequently Visited now checks shortcuts in every MosaicSync Space, including shortcuts inside folders, so a site already saved in Personal is not suggested in Work and vice versa.
Strengthened Sync self-healing so locally delivered synchronized changes can recover after a missed change event without requiring a browser restart.
No new required permissions, Sync/profile schema changes, profile-format changes, remote code, telemetry, localization strings or CSP relaxation.

Reworked Automatic site icons so a new iconless shortcut can recover its favicon automatically without requiring the user to visit the site first. Website Access remains optional and permission requests still require a user gesture.
Consolidated favicon recovery across Firefox and Chromium, including Personal and Work Spaces, while keeping learned/browser-native favicon pixels out of ordinary browser Sync.
Hardened Chromium's browser-native favicon fallback so a transient placeholder-detection failure cannot store Chrome's generic globe as permanent site artwork. Native reads now use a fixed scale factor, avoid forced cache reuse, fail closed when the placeholder identity is unknown, and retry failed sentinel learning.
Fixed favicon recovery scheduling when Chromium can use its permission-free native favicon source, and removed quality-only recovery work when Website Access is revoked so stale upgrade jobs cannot remain pending indefinitely.
Improved favicon compatibility for inaccurate MIME labels and bounded website-declared inline data-image favicons while preserving pre-decode raster/SVG limits.
Improved Frequently Visited with stable first-frame rendering, drag-to-grid creation and device-local site-family hiding. Corrupt/unreadable hidden-site state now fails closed on the cached first frame rather than flashing possibly hidden suggestions.
Strengthened Sync self-healing so locally delivered synchronized changes can recover after a missed change event without requiring a browser restart. Partial shared-ledger delivery no longer causes immediate repair/republish writes while a usable atomic device snapshot is available.
No new required permissions, Sync/profile schema changes, profile-format changes, remote code, telemetry or CSP relaxation.

Changes since 1.26.12

Reworked Automatic site icons around the browser's live optional Website Access capability. New iconless shortcuts can request access from the originating user gesture and are targeted for recovery immediately after grant, without requiring a site visit first.
Consolidated favicon recovery policy so Chromium can use its permission-free native favicon database without host access while Firefox/network discovery remains permission-honest. Recovery covers both Personal and Work Spaces, and permission blocks do not consume website retry budget.
Prevented Chromium's generic native-favicon placeholder from being stored as site artwork and stopped quality-only recovery jobs from remaining permanently pending while Website Access is unavailable.
Improved favicon compatibility for inaccurate HTTP MIME labels and bounded website-declared inline data-image favicons.
Strengthened remote SVG pre-decode protection against decoy root tags in XML comments and bounded SVG bitmap decoding.
Improved Frequently Visited first-frame stability, drag-to-grid creation and device-local registrable-domain hiding, including filtering hidden sites before synchronous first paint.
Strengthened Sync self-healing so equal commit markers no longer suppress reconciliation when actual remote records/settings differ from local state; the periodic watchdog can repair a missed/delayed storage-sync event without requiring a browser restart.
Removed raw user-visible Website Access error text in favor of the existing localized failure path.
No new required permissions, Sync/profile schema changes, profile-format changes, remote code, telemetry or CSP relaxation.

Reworked Automatic site icons so the enabled state now reflects the browser's real optional Website Access capability. Enabling it, or saving a new iconless shortcut while it is enabled, requests that permission from the user gesture; declining leaves the automatic feature off.
New iconless shortcuts now trigger an immediate, targeted favicon-recovery pass after Website Access is granted, without requiring the site to be visited first.
Fixed stale permission/prompt state that could leave automatic favicon recovery silently unavailable, and added permission-added/removed self-healing.
Removed the recovery queue's incorrect global Website Access gate. Chromium can use its local browser favicon cache before remote access is considered; Firefox remote discovery remains explicitly permission-gated.
Permission-blocked favicon jobs no longer consume website retry/backoff budget, and recovery discovery now covers both Personal and Work Spaces.
Includes the unpublished candidate work for improved Frequently Visited behavior, MIME-byte favicon detection, bounded inline favicons and strengthened SVG/remote-image safety.

Changes since 1.26.12:

Frequently Visited now appears in the initial New Tab layout without pushing the shortcut grid down after loading.
Frequently Visited sites can be dragged directly onto an empty grid slot to create a shortcut.
Added Hide this site, which hides the entire site domain and its subdomains on that device.
Added a one-time Website Access reminder for users who have automatic favicon learning enabled but have not granted website permission.
Fixed Firefox Frequently Visited not loading correctly through the native Top Sites adapter.
Strengthened SVG and remote-image dimension validation before browser decoding.
Added Firefox/Chrome regression coverage for these changes.

No new required permissions, Sync schema changes, or profile-format changes.

Hardened automatic favicon handling by rejecting images with unsafe dimensions before browser decoding, including raster and SVG favicons.
Strengthened local image integrity by verifying existing stored assets before reuse and safely repairing missing or corrupted image data.
Added new Firefox/Chrome regression tests for image-resource safety and local asset persistence.
No new permissions, UI changes, Sync/profile-format changes, or external services.

Changes since 1.25.16.1:

• Added separate Light and Dark wallpapers with live appearance switching.
• Improved Settings stability around theme and wallpaper changes, including Firefox-specific repaint protection.
• Added live wallpaper previewing while Settings is open without disrupting the Settings panel.
• Added the ability to drag shortcuts back out of folders onto the main grid.
• Improved bookmark folder colors and visual contrast.
• Added GitHub project links to Settings and Welcome.
• Improved Frequently Visited controls; dependent options now appear only when the feature is enabled.
• Strengthened profile import, SVG/image handling, Sync/state concurrency, cache bounds and general input validation.
• Improved favicon recovery, retry handling and background processing.
• Added additional cross-browser regression coverage for Firefox and Chrome.
• Numerous UI, accessibility, performance and reliability refinements.

Added regression tests covering both localization imports and visible version consistency.

Maintenance and compatibility update.

Improved localization loading to remove a Mozilla AMO validator warning.
Preserved lazy loading for all supported languages.
No user data model, Sync behavior or permissions were changed.
Added regression coverage to prevent the warning from returning.

This release contains no functional regressions or changes to MosaicSync’s privacy model.

Major update to MosaicSync with substantial reliability, security and usability improvements.

Added full profile backup and transfer using portable .mosaicsync files.

Improved Sync reliability, conflict handling and recovery across multiple devices and Spaces.

Improved favicon discovery, caching and recovery.

Expanded localization to 32 languages, covering all 24 official EU languages.

Added numerous UI, accessibility and performance refinements.

Further hardened profile import, image handling, storage, CSP/XSS protections and concurrent-write handling.

MosaicSync remains privacy-first, open source and uses Firefox Sync rather than a MosaicSync-operated synchronization server.

MosaicSync 1.23.1

Major update from 1.20.14.2.

Added Multiple Spaces with renameable Personal/Work layouts.
Shortcuts can now be moved between Spaces by drag-and-drop or from the editor.
MosaicSync now opens in both new tabs and new Firefox windows.
Major Firefox Sync reliability improvements, including safer cross-Space moves, interruption recovery and stronger deletion/conflict handling.
Improved first-run migration and Firefox shortcut importing.
Added the new Aether Flow wallpaper and improved the wallpaper gallery.
Improved Settings, dialog alignment, empty-space onboarding and bookmark behavior.
Improved Automatic light/dark appearance detection.
Updated localization across all supported languages, including a major Neapolitan revision.
Added a localized Made in the EU mark.