What Firefox 158's notes actually date

What happened

Mozilla's developer notes for Firefox 158 say the version is current Beta and ships on October 13, 2026, and that JPEG XL, the image/jxl type, is enabled by default. The notes say the default image Accept header now includes image/jxl, and they cite bug 2065096. The public stable release-notes page says those notes are still being prepared. On October 12, Phoronix reported that binaries were already available and that JPEG XL, previously experimental, is on by default. This page files the split. The page is Futureweb.

What Mozilla's own pages say

The developer note is the schedule: October 13, JPEG XL on, Accept header updated, one bug number. The stable notes page is the status of the notes, which is that they are not finished. The beta notes, from late September, already described JPEG XL support. A version number that has to mean one thing to a packager and another to a headline is the standing software note, what a version number has to mean.

What the October 12 report adds

A packager who ships on the developer note waits until October 13. A reader who fetched a binary on October 12 is following Phoronix, not a finished stable notes page. Both can be reported because they are different documents. image/jxl in the default Accept header is Mozilla's sentence about what the browser will claim to accept. It is not a promise that servers will send that type. Bug 2065096 is the citation on the developer note, not a patch this page is walking through. The beta notes from late September already named JPEG XL support, so the default is not a surprise invented on October 12. What was new on October 12 was the argument about whether the stable bits were already posted. This page keeps the argument open until the stable notes page stops saying the notes are in preparation. Collapsing the two dates would make a ship day neither Mozilla's developer note nor Phoronix stated alone. The stable notes page is the only document here that can retire the split between October 12 and October 13. Phoronix says the binaries can already be fetched and that the format is no longer behind an experimental flag. That is a report about availability on October 12. It does not rewrite Mozilla's ship date. A reader can hold both: bits exist, and the developer note still says October 13. The desk is Software.

Why it matters on this desk

The dependency is a default. Once image/jxl is in the Accept header, a server can offer that type to this browser without a preference the user had to flip. The dependency is not a claim that every site will start sending JPEG XL, and it is not a claim that the stable notes are done. An open-source license, a different obligation, is what a license obligates.

What this page will not collapse

Calling October 12 the stable release would erase the developer note. Calling the format still experimental would erase Phoronix and the beta notes. This page does not pick a winner. It also does not describe how a decoder is wired, because none of the three pages is a patch guide. The networking desk, for a name rather than a browser default, is Networking.

Where the accounts overlap

Mozilla's developer note, the beta notes, and Phoronix agree that Firefox 158 turns JPEG XL on by default. They do not agree on whether October 12 is the ship day. The stable notes page agrees with nobody yet, because it says the notes are still being prepared. The overlap is the default. The disagreement is the calendar.

What to watch next

A finished stable notes page dated October 13, or a correction that moves the ship day, would replace the split. A site that starts sending image/jxl because of the Accept header would be a separate story. Another outlet repeating Phoronix would not. The developer note is the schedule this page will not outrun.

What would change the record

If Mozilla ships on a later day, the October 13 sentence becomes a missed date. If the stable notes, once published, omit JPEG XL, the default claim has to be checked against the binary, not against the beta note. If bug 2065096 is reopened, the citation stays as the note's citation and the status changes. None of those three is the document set on October 12.

What stays a date split

What stays specific is a browser version whose own developer note says October 13, 2026, whose stable notes are still marked in preparation, and whose October 12 coverage says the binaries are already available with JPEG XL on by default. The format identifier is image/jxl. The bug number on the developer note is 2065096. The Accept header change is Mozilla's sentence, not an inference from a screenshot. A reader who needs one date should use October 13 for the ship note and October 12 for the report that the bits were already posted. Collapsing those into a single day would be a new claim none of the three pages makes. The beta notes are the earlier document that already named the format. They are context, not the stable release.