Hi Mike,
Thank you for pointing out the OT extension limit. Similar to the Writer
API, I have updated the Chromestatus page to reflect OT extension by 3
milestones.
Please see comments on the progress below.
- Draft spec (early draft is ok, but must be spec-like and associated
with the appropriate standardization venue, or WICG)
- The shared Writing Assistance APIs draft spec
<https://webmachinelearning.github.io/writing-assistance-apis/> is
relatively comprehensive and has already supported the launch of the
Summarizer API, plus Shared Infrastructure
<https://webmachinelearning.github.io/writing-assistance-apis/#supporting>
already leveraged
<https://webmachinelearning.github.io/translation-api> for Translator
<https://chromestatus.com/feature/5172811302961152> and
LanguageDetector
<https://chromestatus.com/feature/6494349985841152> launches.
Reilly Grant has stepped up to take on Editor duties for this
spec through
its incubation in the Web Machine Learning Community Group.
- TAG review (see exceptions)
- The Writing Assistance APIs
<https://github.com/w3ctag/design-reviews/issues/991> TAG review
intentionally
timed
<https://github.com/w3ctag/design-reviews/issues/991#issuecomment-3166120120>
out
to focus review efforts on the in-progress Prompt API
<https://github.com/w3ctag/design-reviews/issues/1093> TAG review
request. Since these APIs share much infrastructure, we look forward to
receiving thoughtful and broad TAG design feedback.
- signals requests
- These APIs are being discussed within the WebML CG which has
participation from other browser vendors and Microsoft intends to follow
our lead on launching these APIs using their own models.
- Outreach for feedback from the spec community
- Chrome's
https://github.com/webmachinelearning/writing-assistance-apis/issues/33
- WPT tests
- We've explained significant progress on Writer and Rewriter WPT
coverage in the original message. While not fully covered: "The API
surface is reasonably well tested with mocked models, but
production model
downloading and non-deterministic outputs are not fully tested at the
web-platform-tests layer. The explainer discusses this in
https://github.com/WICG/writing-assistance-apis/blob/main/README.md#specifications-and-tests
."
Thanks,
Deepti
On Tue, Oct 28, 2025 at 11:25 AM Mike Taylor <[email protected]> wrote:
> Similar to the Writer API, this can only be extended for 3 months. See
> similar questions on progress below, thanks.
> On 10/28/25 11:40 a.m., Deepti Bogadi wrote:
>
> Gentle reminder to review the Intent to Extend Experimentation for the
> Rewriter API. Let me know if you have any questions.
>
> Thanks,
> Deepti
>
> On Wed, Oct 22, 2025 at 11:18 AM Deepti Bogadi <[email protected]>
> wrote:
>
>> Contact emails
>>
>> [email protected], [email protected],[email protected]
>>
>> Explainer
>>
>>
>> https://github.com/explainers-by-googlers/writing-assistance-apis/blob/main/README.md
>>
>> Specification
>>
>> https://webmachinelearning.github.io/writing-assistance-apis/#rewriter-api
>>
>> Summary
>>
>> The Rewriter API transforms and rephrases input text in requested ways,
>> backed by an on-device AI language model. Developers may use this API to
>> remove redundancies within a text in order to fit into a word limit,
>> rephrase messages to suit the intended audience or to be more constructive
>> if a message is found to use toxic language, rephrasing a post or article
>> to use simpler words and concepts and more. An enterprise policy
>> (GenAILocalFoundationalModelSettings) is available to disable the
>> underlying model downloading which will render the API unavailable.
>>
>> Blink component
>>
>> Blink > AI > Writing Assistance
>> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%20%3E%20AI%20%3E%20Writing%20Assistance%22>
>>
>> Web Feature ID
>>
>> No information provided
>>
>> TAG review
>>
>> https://github.com/w3ctag/design-reviews/issues/991
>>
>> TAG review status
>>
>> Pending
>>
>> Origin Trial Name
>>
>> Rewriter API
>>
>> Chromium Trial Name
>>
>> AIRewriterAPI
>>
>> Origin Trial documentation link
>>
>>
>> https://github.com/webmachinelearning/writing-assistance-apis/blob/main/README.md#rewriter-api
>>
>> WebFeature UseCounter name
>>
>> Rewriter_Create
>>
>> Risks
>>
>>
>> Interoperability and Compatibility
>>
>> This feature has definite interoperability and compatibility risks, due
>> to the likelihood that different implementations will use different
>> language models, prompts, and fine-tunings, and even within a single
>> implementation such as Chrome, these pieces will likely change over time.
>> Additionally, not all browsers and operating systems will have a built-in
>> language model to expose, and not all devices will be powerful enough to
>> run one effectively. We are taking a variety of steps to attempt to
>> mitigate these risks. For example, the specification is designed to allow
>> the API to be backed by a cloud-based language model. This approach could
>> extend the functionality to a wider range of devices and users. The API is
>> designed to abstract away the specifics of the underlying language model,
>> including prompts and fine-tuning. This prevents developers from relying on
>> specific outputs, ensuring they receive rewritten text rather than
>> structured data that might vary across implementations. Finally, the API
>> surface is designed with many clear points of failure, that encourage the
>> developer to probe for capabilities ahead of time and fall back to other
>> techniques if a capability is not available. Nevertheless, interoperability
>> and compatibility risk remains high for these sorts of APIs, and we'll be
>> closely monitoring it during the experiment period.
>>
>> Gecko: Negative (
>> https://github.com/mozilla/standards-positions/issues/1067)
>>
>> WebKit: No signal (
>> https://github.com/WebKit/standards-positions/issues/393)
>>
>> Web developers: Mixed signals (
>> https://github.com/WICG/proposals/issues/163) Prototyping with partners
>> behind a flag revealed enthusiasm and many prototypes built, from which we
>> drew the discussion of potential use cases [1]. Feedback on the WICG thread
>> was more mixed. Some themes we saw include: asking for more capabilities
>> (e.g. full prompting of a language model instead of higher-level APIs (our
>> response at [2]); multi-modal support); desire to make sure the API
>> actually works robustly in many real-world use cases; removal of any
>> safety/ethical safeguards; and confusion about client-side vs. cloud APIs.
>> [1]:
>> https://github.com/WICG/writing-assistance-apis/blob/main/README.md#summarizer-api
>> [2]:
>> https://github.com/WICG/writing-assistance-apis/blob/main/README.md#directly-exposing-a-prompt-api
>>
>> Other signals:
>>
>> Activation
>>
>> This feature would definitely benefit from having polyfills, backed by
>> any of: cloud services, lazily-loaded client-side models using WebGPU, or
>> the web developer's own server. We anticipate seeing an ecosystem of such
>> polyfills grow as more developers experiment with this API.
>>
>> WebView application risks
>>
>> Does this intent deprecate or change behavior of existing APIs, such that
>> it has potentially high risk for Android WebView-based applications?
>>
>> No information provided
>>
>>
>> Goals for experimentation
>>
>> Although developers have prototyped using the behind-a-flag
>> implementation and given good feedback, several partners are interested in
>> testing out the API with real users. We're looking forward to getting
>> feedback from such testing, especially with regards to output quality,
>> multilingual support, and what types of input data are handled well vs.
>> poorly. We also want to understand whether we've found the right set of
>> options to offer to control the output, and whether the resulting output
>> reflects those controls to the extent that developers expect.
>>
>> Reason this experiment is being extended
>>
>> Rewriter API suffers from perceived quality issues and a critical
>> language support disconnect. These APIs are currently not production-ready
>> for many use cases, particularly those outside of English. In addition, we
>> are also seeing low adoption in the OT phase for this API. Hence, we are
>> requesting the extension of the trial to give us time to collect more
>> feedback from our partners and make the API more robust and resilient.
>>
> Can you please comment on progress in these areas, per
> https://www.chromium.org/blink/launching-features/#origin-trials?
>
> Draft spec (early draft is ok, but must be spec-like and associated with
> the appropriate standardization venue, or WICG)
> TAG review (see exceptions)
> signals requests
> Outreach for feedback from the spec community
> WPT tests
>
>
>> Ongoing technical constraints
>>
>> As discussed above, not all devices are capable of running the language
>> models required to implement this API. The availability() function allows
>> developers to feature-detect whether the current device can support the API.
>>
>> Debuggability
>>
>> It is possible that giving DevTools more insight into the
>> nondeterministic states of the model, e.g. random seeds, could help with
>> debugging. See related discussion at
>> https://github.com/explainers-by-googlers/prompt-api/issues/9.
>>
>> Will this feature be supported on all six Blink platforms (Windows, Mac,
>> Linux, ChromeOS, Android, and Android WebView)?
>>
>> No
>>
>> Not all platforms will come with a language model. In particular, in the
>> initial stages we are focusing on Windows, Mac, and Linux.
>>
>> Is this feature fully tested by web-platform-tests
>> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>
>> ?
>>
>> No
>>
>> The API surface is reasonably well tested with mocked models, but
>> production model downloading and non-deterministic outputs are not fully
>> tested at the web-platform-tests layer. The explainer discusses this in
>> https://github.com/WICG/writing-assistance-apis/blob/main/README.md#specifications-and-tests
>> .
>>
>> DevTrial instructions
>>
>>
>> https://docs.google.com/document/d/1v6-fOC13zS3S-bOLuqIRbzgmia_aPGJl-wzOx4ItSVE/edit?usp=sharing
>>
>> Flag name on about://flags
>>
>> rewriter-api-for-gemini-nano
>>
>> Finch feature name
>>
>> AIRewriterAPI
>>
>> Requires code in //chrome?
>>
>> True
>>
>> Tracking bug
>>
>> https://issues.chromium.org/issues/358214322
>>
>> Launch bug
>>
>> https://launch.corp.google.com/launch/4396842
>>
>> Non-OSS dependencies
>>
>> Does the feature depend on any code or APIs outside the Chromium open
>> source repository and its open-source dependencies to function?
>>
>> Yes: this feature depends on a language model, which is bridged to the
>> open-source parts of the implementation via the interfaces in
>> //services/on_device_model.
>>
>> Estimated milestones
>>
>> Origin trial desktop first
>>
>> 137
>>
>> Origin trial desktop last
>>
>> 142
>>
>> Origin trial extension 1 end milestone
>>
>> 148
>>
>> DevTrial on desktop
>>
>> 129
>>
>> Anticipated spec changes
>>
>> Open questions about a feature may be a source of future web compat or
>> interop issues. Please list open issues (e.g. links to known github issues
>> in the project for the feature specification) whose resolution may
>> introduce web compat/interop risk (e.g., changing to naming or structure of
>> the API in a non-backward-compatible way).
>>
>> At this point all known proposed changes have been incorporated into the
>> specification and implementation.
>>
>> Link to entry on the Chrome Platform Status
>>
>> https://chromestatus.com/feature/5112320150470656?gate=5133588907556864
>>
>> Links to previous Intent discussions
>>
>> Intent to Prototype:
>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra9Jhe7o59mX5tJPD%3DcZQb2oL3mNi-T57wA86fPXn55OPw%40mail.gmail.com
>>
>> Intent to Experiment:
>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAM0wra8dnNHXKM26MvQxZ6LBE16PUbvH6-GH5B3Z2WDv4uH0WQ%40mail.gmail.com
>>
>> This intent message was generated by Chrome Platform Status
>> <https://chromestatus.com/>.
>>
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