Hi Mike, Thanks for checking in! Here is a quick update on where we stand across those areas:
Milestones: As noted in the intent, we are looking to extend the experiment through Chrome 159. This aligns with the standard extension policy and gives developers sufficient time to test the updated categorical presets. Draft Spec & TAG Review: The draft specification <https://webmachinelearning.github.io/prompt-api/> and explainer <http://LanguageModelSamplingMode> have been updated to reflect the new AILanguageModelSamplingMode enum structure. TAG review is currently pending. Outreach for feedback & Signals: While official vendor signals are still pending, we've gathered helpful qualitative feedback from the community. This input surfaced the large gaps in our initial presets, which directly motivated this update. On the quantitative side, our latest developer survey data shows: - 45.8% of developers actively tune parameters (vs. 39.2% who rely on defaults). - Among those who tune parameters, 54.5% are favorable to using semantic presets, while 24.5% prefer raw parameter access. Note that this demand for tuning largely reflects broader developer habits across LLMs in general, rather than Built-in AI specifically. If we need even more signal during this extension, we plan to tap into WEC/partnerships or reach out to the EPP mailing list. WPT tests & Eval framework: Web Platform Tests currently cover the API shape and surface. However, for evaluating the actual model outputs (the effects of sampling parameters), our ultimate destination is the work in progress with other browser vendors on shared use-case benchmarks. We are using Web AI Studio as an initial stepping stone toward that broader evaluation framework. Let me know if you need any additional details! Cheers, Isaac On Thu, Aug 20, 2026 at 10:18 AM Mike Taylor <[email protected]> wrote: > Hi there, > > Can you clarify what milestones you are looking to experiment on, and any > progress on the following since the initial experiment? > > Draft spec > TAG review > Signals requests > Outreach for feedback from the spec community > WPT tests (or some kind of open eval framework) > > thanks, > Mike > On 8/19/26 12:37 p.m., 'Isaac Ahouma' via blink-dev wrote: > > *Contact emails *[email protected], [email protected] > > Explainer > https://github.com/webmachinelearning/prompt-api#sampling-parameters > > Specification https://webmachinelearning.github.io/prompt-api/ > > Summary The Prompt API Sampling Parameters allow developers to control > the output variety of the built-in AI language model. Instead of exposing > raw numerical parameters (e.g. topK and temperature) which can behave > inconsistently across different underlying model families and versions, > this feature introduces a categorical samplingMode enum. This allows the > browser to handle the heavy lifting of mapping semantic presets to optimal > raw parameters for a specific underlying model, providing developers with > the necessary granularity to tune responses while maintaining cross-browser > interoperability. enum AILanguageModelSamplingMode { "most-predictable", > // For strict consistency/factual extraction "predictable", > // For highly focused outputs "slightly-predictable", // For > moderately focused, consistent outputs "balanced", // The > default state for standard prompting "slightly-creative", // For > moderately varied, expressive outputs "creative", // For > tasks favoring variety over strict facts "most-creative" // > For maximum token diversity and brainstorming }; > > Blink component Blink>AI>Prompt > > Web Feature ID https://webstatus.dev/features/languagemodel > > TAG review status Pending > > Link to previous “Intent to Experiment” blink-dev discussion > https://groups.google.com/a/chromium.org/g/blink-dev/c/4KvH5XEBYtE > > Goals for experimentation Our primary goal during this extension is to > gather real-world usage data on the newly expanded categorical presets to > see which modes developers gravitate toward most. We will use this data and > developer feedback to conduct more concerted medium-term mode evaluations. > Specifically, we want to evaluate developer adoption of this expanded > spectrum, and validate that the new granularity effectively covers the > previously identified dead zones. > > Experimental timeline The extended experiment will continue through > Chrome 159. > > Reason this experiment is being extended We are extending this experiment > because we are actively iterating on the API surface based on developer > feedback. During this trial, we received developer feedback requesting > predictable space granularity to cover dead zones while restoring the > balanced preset to the API default parameters. We have expanded the > preset enum values to cover these dead zones, and we need the extended > timeline to give developers sufficient time to integrate and test these > specific changes. > > Interoperability and Compatibility Risks The original raw parameters were > excluded from the initial Prompt API launch due to cross-browser > interoperability concerns. By refining the categorical sampling modes to > provide better coverage of the predictable space based on developer > feedback, we maintain the cross-browser interoperability benefits of > semantic presets while offering the necessary granularity developers > requested. WebView application risks None > > Ongoing technical constraints None 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/webmachinelearning/prompt-api/issues/9. > > Will this feature be supported on all six Blink platforms (Windows, Mac, > Linux, ChromeOS, Android, and Android WebView)? No, the Prompt API > currently supports Windows, Mac, Linux, and ChromeOS. > > Is this feature fully tested by web-platform-tests? No; while the API > shape is fully tested, automated testing of sampling parameter effects on > probabilistic model response is not readily feasible; instead we conduct > rounds of evaluations on configuration updates. > > Flag name on about://flags prompt-api-sampling-mode > > Finch feature name AIPromptAPIParams > > Requires code in //chrome? True > > Tracking bug https://crbug.com/502214118 > > Launch bug https://launch.corp.google.com/launch/4463387 Link to entry on > the Chrome Platform Status: > https://chromestatus.com/feature/6325545693478912 > > > > -- > You received this message because you are subscribed to the Google Groups > "blink-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion visit > https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAFk4SLZXUY8FQTQQrtLHkzLnkxkgJ7XXFBhDEAQSvy6XiYKgaQ%40mail.gmail.com > <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAFk4SLZXUY8FQTQQrtLHkzLnkxkgJ7XXFBhDEAQSvy6XiYKgaQ%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. 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