Improves complete Personal + Work Sync recovery, New Tab startup performance and Firefox rendering stability. Fixes the one-time white startup pill without breaking the MosaicSync hello mascot; prevents Light mode from briefly painting Dark tiles; keeps Settings stable while Separate Light/Dark Wallpapers or first-time Frequently Visited changes persist; fixes drag/drop localization; and improves general favicon quality ranking so oversized manifest/touch assets do not automatically displace a better conventional favicon. No new permissions.

Improves whole-profile Sync recovery and New Tab startup reliability/performance. Personal + Work now recover as one verified profile with previous-generation fallback, safe fresh-device waiting/merge behavior, and Work self-repair. New Tab keeps its fast critical launcher path while eliminating the Firefox one-time white-pill trigger: first logo hover no longer loads secondary CSS, and deferred CSS is isolated from already-painted launcher controls. Also improves wallpaper preview isolation, Frequently Visited preference Sync and shortcut hover. No new permissions.

Improves whole-profile Sync recovery and New Tab startup reliability/performance. Personal + Work now recover as one verified profile with previous-generation fallback, safe fresh-device waiting/merge behavior, and Work self-repair. New Tab uses a smaller critical path, visible-first artwork hydration and on-demand secondary UI CSS; Firefox no longer receives a deliberate post-first-paint stylesheet recascade. Also improves wallpaper preview isolation, Frequently Visited preference Sync and shortcut hover. No new permissions.

1.27.8.6 is a narrow Firefox first-frame native-control hardening follow-up to 1.27.8.5. The previous CSS-ownership cleanup was correct but did not eliminate the reported transient rounded "pill" on the user's Firefox hardware. Source review then found that the custom launcher Settings button remained a native <button> with the default appearance: auto, while a deferred stylesheet introduces generic button font/color rules after first paint.

This release explicitly suppresses native widget appearance in blocking critical CSS for the fully custom-styled Settings, Bookmarks and Space launcher buttons. The change is intentionally minimal so it can test/fix the native-control hypothesis without altering the delayed secondary-style architecture or any product/Sync behavior.

Hardened Firefox New Tab launcher controls against a transient native-button flash during startup. The custom Settings, Bookmarks and Space buttons now explicitly use appearance: none in first-frame critical CSS, with new cross-browser regression coverage. No permissions, Sync/profile changes, CSP relaxation, telemetry or feature changes.

Fixed a brief Firefox New Tab startup artifact caused by the deferred secondary stylesheet re-declaring launcher-visible Settings-button styles. Launcher tile and folder-mosaic artwork rules are now critical-only as well, and new regressions enforce the critical/secondary CSS ownership contract. No new permissions, Sync/profile changes, CSP relaxation, telemetry or feature changes.

Scope

1.27.8.4 is the third focused New Tab performance/stability pass for older/slower desktop CPUs. It refines the 1.27.8.3 critical-path work by removing duplicated critical CSS from the deferred UI stylesheet, shrinking the blocking launcher stylesheet further, starting authoritative local-state I/O before the large ES-module graph evaluates, and warming hidden folder artwork in bounded idle chunks instead of one delayed bulk read.

The release also fixes the Settings blanking regression triggered by separate Light/Dark wallpaper controls, synchronizes the Frequently Visited Show/Count preference while keeping actual browser-derived sites/history and permission device-local, and makes the paint-only shortcut hover enlargement more noticeable.

There are no new permissions or host permissions, no Sync shortcut/profile/container schema change, no conflict/tombstone change, no CSP relaxation, no telemetry/remote code, and no reduction of URL/image/SVG validation or artwork quality.

Mozilla Add-ons concise changelog

Performance/stability follow-up for older/slower computers. MosaicSync now uses a smaller launcher-only critical stylesheet plus a truly secondary-only UI stylesheet, starts authoritative local-state I/O before the main module graph evaluates, and hydrates hidden folder artwork in bounded idle chunks. Fixed the Settings blank/white regression when separate Light/Dark wallpaper controls change. Frequently Visited Show/Count now follows the synchronized MosaicSync profile while actual sites/history and the browser permission remain device-local. Shortcut hover enlargement is more noticeable without layout shift. No new permissions, CSP relaxation, telemetry or image-quality reduction.

1.27.8.3 is the second focused New Tab performance pass for older/slower desktop CPUs. It targets work that still sat on the first-visible/first-interactive path after 1.27.8.2: blocking CSS, late authoritative local-storage I/O, cold-start destruction/reconstruction of an already-valid bootstrap grid, invisible closed-folder artwork, and eager construction of a future-write baseline.

It does not change Sync/profile/state schemas, synchronized conflict/tombstone semantics, permissions, host permissions, CSP strength, navigation safety, image/SVG trust-boundary validation, import handling, telemetry policy, remote-code policy or artwork quality.

Mozilla Add-ons concise changelog

New Tab performance follow-up for older/slower computers. MosaicSync now loads a much smaller critical launcher stylesheet before first paint, overlaps authoritative local-storage I/O with UI setup, safely adopts an exact-matching cold-start bootstrap grid instead of rebuilding it, hydrates only the four visible artwork cells of closed folders before perceived completion, and reuses the exact compact persisted state as its future-write concurrency baseline. Added local-only startup phase timings for profiling. The full renderer remains the fallback whenever bootstrap adoption is uncertain. No new permissions, Sync/schema changes, CSP relaxation, telemetry or image-quality reduction.

New Tab startup-performance release for older/slower computers. Matching cached tile previews now stay visible until full artwork is decoded, avoiding the preview/fallback/full-image flash. Startup reuses already-validated local-asset identities instead of repeatedly hashing the same image bytes, defers heavyweight custom-wallpaper hydration until after shortcut paint, limits closed-folder first-frame preview work to the four visible mosaic children, and requests asynchronous image decoding. No Sync/security behavior, permissions or image quality changed.

Sync hardening follow-up. Recovery-snapshot quota/size failures are now tracked consistently across Personal, Work, cross-Space, bootstrap and reconciliation paths instead of silently losing the safety warning. Added real two-computer Firefox/Chrome Sync simulations with partial/out-of-order delivery, a local edit during bootstrap, missed Sync events, watchdog recovery and final convergence. Added root-last quota fault injection proving the previous complete generation remains authoritative. No new permissions.

Sync reliability release. MosaicSync now protects Personal and Work as one complete profile safety generation, retains the previous verified generation for fallback, waits instead of finalizing a half-restored fresh profile, preserves local edits made while Sync is still arriving, and can repair a torn Work ledger from a verified complete profile. Also adds a subtle Firefox-style no-layout-shift shortcut hover. No new permissions.

Fixes a device-local favicon propagation edge case where a shortcut could already contain newly learned automatic artwork while its visible New Tab tile remained on the fallback letter. Device-local favicon/cache updates intentionally preserve synchronized workspace clocks, so New Tab no longer treats a matching clock alone as proof that a storage.local event is an ignorable write echo. The existing lightweight device-artwork path now applies those changes directly to visible shortcut and folder artwork.

The manual Choose detected favicon workflow now also exposes already-learned automatic favicon/browser artwork as an available detected candidate, while keeping uploaded and built-in artwork separate. Existing pixels are deduplicated against fresh discovery.

The picker now distinguishes a successful website scan with no icon candidates from an actual page-inspection/network failure, using a localized inspection-failure state instead of incorrectly reporting that no icons exist.

Regression coverage includes declared inline SVG and PNG favicon metadata based on a real-world page structure.

The automatic favicon resolver, ranking, winner selection, single-flight, quality-upgrade and fallback behavior remain unchanged.

No new permissions or host permissions, state/Sync/profile schema changes, CSP relaxation, telemetry or remote code.

Refines shortcut artwork proportions: contained shortcut images and bundled top-level icons now occupy approximately 70% of the tile while tile dimensions, grid density, the existing size slider and Cover-mode edge-to-edge artwork remain unchanged.

User-triggered detected-favicon discovery can now be cancelled when the shortcut editor is closed or reset. MosaicSync uses a request-ID protocol across extension messaging while the background worker owns the corresponding cancellation controller, allowing in-flight manual favicon/page/manifest requests to be aborted without sending non-cloneable AbortSignal objects between extension contexts.

The automatic favicon resolver, ranking, winner selection, quality mode and single-flight behavior remain unchanged.

Regression coverage now additionally verifies Website Access revocation against cached favicon choices, aggregate favicon-cache retention limits, request-isolated cancellation, additional Public Suffix List edge cases and more precise CSS class-reference auditing.

No new permissions or host permissions, state/Sync/profile schema changes, CSP relaxation, telemetry or remote code.

Improves shortcut artwork proportions while keeping tile dimensions and layout density unchanged. Contained shortcut artwork now occupies approximately 76% of each tile across the existing size-slider range, with bundled MosaicSync shortcut icons at 78%. Cover-style artwork remains edge-to-edge.

The user-invoked detected-favicon picker now performs a live Website Access permission refresh before consulting its short-lived in-memory cache, preventing recently revoked access from exposing stale cached candidates. Redirect-origin favicon fallback work also shares the existing bounded two-wide discovery batch for lower latency.

The existing automatic favicon resolver, ranking, winner selection, quality mode, retry behavior and single-flight logic are unchanged.

Public Suffix List runtime generation now records deterministic semantic counts/hash metadata and performs additional sanity checks for duplicates, malformed rules and unexpected rule-set collapse. Functional tests compare source and compact runtime behavior for exact, private, wildcard, exception and IDN cases.

Package-size regression monitoring now covers missing/new categories and significant individual-file growth in addition to overall/category growth. Compact localization receives additional special-character and ordering-equivalence coverage.

No new permissions or host permissions, state/Sync/profile schema changes, CSP relaxation, telemetry or remote code.

Reduces runtime package size substantially without removing features or source readability. MosaicSync's deterministic build now generates a rules-only Public Suffix List runtime artifact from the complete reviewed upstream source and compact runtime locale modules from the existing 32 readable translation catalogs. Exhaustive regressions verify exact PSL-rule equivalence and exact localization key/value equivalence.

The manual Choose detected favicon workflow is also refined: candidate image work is bounded to two concurrent fetch/decode jobs, immediate repeated requests for the exact URL can reuse a small 30-second in-memory cache, closing the shortcut editor invalidates in-flight discovery and releases candidate data, and detected choices expose localized browser/site source and image dimensions through tooltip/accessibility metadata.

Site-declared inline favicon candidates remain supported through the existing bounded image/SVG validation pipeline.

The automatic favicon resolver, ranking, winner selection, retry/single-flight behavior and favicon quality are unchanged from 1.27.3.

A deterministic package-size report/baseline is now included for detecting accidental future runtime growth.

No new permissions or host permissions, state/Sync/profile schema changes, CSP relaxation, telemetry or remote code.

Adds a user-invoked Choose detected favicon option to the shortcut editor. When requested, MosaicSync can present up to eight deduplicated, validated site-icon candidates discovered using the existing bounded favicon/image/SVG safety primitives, allowing the user to choose the exact artwork they prefer. The selected pixels become explicit user artwork and are protected from later automatic favicon replacement; the existing Sync this image option remains opt-in.

The existing automatic favicon resolver and winner-selection algorithm are unchanged from 1.27.2.

Open folder popovers now remain attached to their originating folder while the MosaicSync page scrolls as well as during window resizing, using animation-frame-coalesced repositioning.

Recent-mode drag/drop containment is further hardened, and ordinary same-tab shortcut navigation no longer schedules an unnecessary Recent-grid render immediately before leaving the New Tab page while still recording the local usage timestamp.

Regression coverage has been expanded for manual favicon discovery, automatic-resolver identity, Recent drag containment, folder scroll positioning, cross-device artwork conflict semantics and localization.

Keeps the device-local Recently opened order strictly presentation-only by preventing top-level grid drops from using temporary Recent visual slots as synchronized Manual positions. Frequently Visited drag-to-grid and folder-child extraction-to-grid are unavailable while Recent mode is active, while normal Add shortcut continues to choose a canonical free Manual position. Manual-mode drag/drop is unchanged.

The Edit shortcut dialog is modestly tightened so normal desktop viewports no longer show an internal right-side scrollbar; the existing overflow fallback remains for genuinely short screens.

This release also adds defense-in-depth validation for built-in icon/color metadata in the disposable render manifest and normalizes malformed built-in artwork-source metadata without a valid icon back to ordinary icon recovery. Regression coverage now executes Recent/Manual drop paths, full folder-popover positioning geometry, and first-paint versus authoritative Recent-order equivalence.

No new permissions or host permissions, persisted schema changes, favicon resolver changes, CSP relaxation, telemetry or remote code.

Adds a compact Open all in background action to folders, brings folder popovers significantly closer to their originating tile, and introduces synchronized shortcut color accents plus 13 bundled MosaicSync shortcut icons. A new optional Recently opened view orders shortcuts using bounded device-local usage timestamps without modifying or synchronizing the canonical manual layout.

Built-in icon and color metadata are additively supported by the state/Sync model and by both synchronous and session-based startup render paths. The lightweight session snapshot validates these presentation fields and authoritative reconciliation detects incomplete/older projections to prevent first-frame visual inconsistencies.

Improves recovery when the optional browser permission used by Frequently Visited is unavailable. The user's enabled preference is now retained independently from the live Top Sites permission, and Settings provides a localized direct permission-recovery action instead of requiring the feature to be toggled off and on again. MosaicSync also refreshes Frequently Visited when browser permissions change and performs a delayed startup reconciliation so an already-granted permission that becomes available shortly after extension startup can restore suggestions automatically.

Profile import now preserves the Frequently Visited preference independently from installation-local permission state.

Regression coverage was also extended to exercise the real per-shortcut stale-result protection behind 1.26.17.6's exact-URL favicon single-flight optimization.

No new permissions, host permissions, Sync/profile formats, persisted schemas, CSP behavior, favicon resolver behavior, telemetry or remote code were introduced.

Improves runtime efficiency by coalescing automatic favicon-recovery jobs that target the exact same normalized URL and quality mode, while preserving independent discovery for different pages and all existing stale-result, retry and safety protections. Frequently Visited now reuses its explicit-shortcut host index while shortcut state is unchanged, avoiding redundant cross-Space/folder scans, and production performance diagnostics are gated behind the existing local development flag.

The release also strengthens regression coverage by behaviorally executing the synchronous first-paint renderer against hostile URLs and by extending prototype-pollution checks throughout the normalized profile tree.

No permissions, host permissions, Sync/profile formats, persisted schemas, CSP, telemetry or remote-code behavior changed.

Centralizes HTTP(S)-only shortcut URL validation into one shared fail-closed safety primitive used by state normalization, session rendering, first-paint rendering and the authoritative New Tab UI. The synchronous first-frame renderer now independently validates shortcut and Frequently Visited href targets as an additional defense-in-depth layer. Profile-import adversarial coverage was also expanded to test checksum-valid proto, constructor and prototype keys across all relevant package/state boundaries. No permissions, Sync/profile formats, persisted schemas, telemetry, remote code or CSP behavior changed.

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.