Define "present credential requests" algorithm. by marcoscaceres · Pull Request #419 · w3c-fedid/digital-credentials

marcoscaceres · 2025-12-16T10:27:37Z

Defines the "present the credential request" algorithm — the core user-facing part of the Digital Credentials flow that happens after validation passes.

What the algorithm does

Once the credential requests have been validated (by the "prepare" algorithm), this algorithm:

Constructs a request context — bundles the validated requests with the top-level and document origins, so the platform/chooser knows who is asking and from where.
Presents a digital credential chooser — a UA-provided UI that shows the user available credentials from registered holders. The user can select a credential, cancel, or the operation can be aborted via an AbortSignal.
Handles abort — if the signal fires, the algorithm returns (the abort callback was already wired up by the "prepare" steps).
Handles cancellation — rejects with AbortError.
Maps platform errors — translates platform-specific failures to web-facing errors: NotAllowedError (permission denied), TypeError (malformed request data), InvalidStateError (concurrent request), or OperationError (catch-all).
Processes the response — parses the holder's response as JSON, validates it's an object, constructs a DigitalCredential instance with data and protocol, resolves the promise, and cleans up coordinator state.

New terms introduced

Digital credential chooser — the UA-provided UI for credential selection
Request context — a struct carrying requests, top origin, and document origin into the chooser

Closes #419

The following tasks have been completed:

Modified Web platform tests (digital-credentials: test conditional mediation rejects with TypeError web-platform-tests/wpt#59087)

Implementation commitment:

WebKit
Chromium (link to issue)
Gecko (link to issue)

Documentation and checks

Preview | Diff

…if AbortSignal races with picker result rdar://163295172 https://bugs.webkit.org/show_bug.cgi?id=305363 Reviewed by Pascoe. Fix race and crash in CredentialRequestCoordinator by settling promises only after picker teardown and safely handling abort reasons. Ensure credential requests always settle after the picker UI has fully torn down. This change: - Defers promise settlement until the picker dismiss callback fires - Better handles aborts during presentation and teardown - Avoids capturing unprotected JSValues across async boundaries - Keeps coordinator state transitions more consistent (with better checks) It also more closely follows the spec: w3c-fedid/digital-credentials#420 w3c-fedid/digital-credentials#419 * LayoutTests/imported/w3c/web-platform-tests/digital-credentials/get.tentative.https-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/digital-credentials/non-fully-active.https-expected.txt: * LayoutTests/imported/w3c/web-platform-tests/digital-credentials/non-fully-active.https.html: * Source/WebCore/Modules/identity/CredentialRequestCoordinator.cpp: (WebCore::CredentialRequestCoordinator::PickerStateGuard::PickerStateGuard): (WebCore::CredentialRequestCoordinator::PickerStateGuard::~PickerStateGuard): (WebCore::CredentialRequestCoordinator::setState): (WebCore::CredentialRequestCoordinator::prepareCredentialRequest): (WebCore::CredentialRequestCoordinator::handleDigitalCredentialsPickerResult): (WebCore:: const): (WebCore::CredentialRequestCoordinator::dismissPickerAndSettle): (WebCore::CredentialRequestCoordinator::abortPicker): (WebCore::CredentialRequestCoordinator::contextDestroyed): (WebCore::CredentialRequestCoordinator::~CredentialRequestCoordinator): (): Deleted. (WebCore::CredentialRequestCoordinator::presentPicker): Deleted. (WebCore::CredentialRequestCoordinator::finalizeDigitalCredential): Deleted. * Source/WebCore/Modules/identity/CredentialRequestCoordinator.h: * Source/WebCore/Modules/identity/DigitalCredential.cpp: (WebCore::DigitalCredential::discoverFromExternalSource): * Source/WebCore/SaferCPPExpectations/UncountedCallArgsCheckerExpectations: Canonical link: https://commits.webkit.org/305868@main

mohamedamir

I like the direction in general, I have added a couple of comments

Thank you, @marcoscaceres

hlflanagan · 2026-01-22T14:43:36Z

Discussed in 21 January 2026 Series B call

hlflanagan · 2026-02-09T17:39:05Z

Discussed on 2026-02-09 call. Editors will bring this back to the group after more research for best practices and to suggest direction.

hlflanagan · 2026-04-20T16:42:32Z

Discussed at the 20 April 2026 call. Note the idea to create a list of v2 (breaking changes) items for DC API, including calling origin and top level origin. Will bring back to next week's call.

Co-authored-by: Mohamed Amir Yosef <mohamed.amir@gmail.com> Co-authored-by: Ted Thibodeau Jr <tthibodeau@openlinksw.com>

- Replace selectedRequest with platform-returned protocol identifier, since neither WebKit nor Chromium know which request was selected - Rename parsedDataOrError to parsedResponseDataOrError for clarity - Move JSON parsing, validation, and credential construction inside the queued global task so they execute in the correct realm - Unify success/error ordering: cleanup abort, settle promise, null active promise, set idle (eliminates double-task-hop for errors) - Remove document origin from request context (CTAP only supports one origin, Chromium does not send it); tracked in #504 - Derive top-level origin from environment settings object - Rename "top origin" to "top-level origin" for clarity - Wrap chooser and response handling in [=In parallel=] - Fix "wait for the user to do" framing to "wait for outcomes" - Fix grammar in abort note and protocol note

marcoscaceres · 2026-04-29T11:41:22Z

@mohamedamir all suggestions applied.

@hlflanagan, @mohamedamir filed a bug about the iframe's origin #504 to fix in the future.

I think we are done 🥳

Confirmed that apart from a few error codes this matches 1:1 both WebKit and Chrome.

timcappalli

LGTM with the name change (initiate)

…redential request" Agent-Logs-Url: https://github.com/w3c-fedid/digital-credentials/sessions/727fd1f7-e1e3-48d7-a636-a4c14b7590a1 Co-authored-by: marcoscaceres <870154+marcoscaceres@users.noreply.github.com>

mohamedamir

LGTM after replacing all mentions of "present" with "initiate"

Co-authored-by: Mohamed Amir Yosef <mamir@chromium.org>

wseltzer · 2026-04-29T23:14:13Z

29 April minutes

SHA: 0bbd3e3 Reason: push, by marcoscaceres Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

marcoscaceres force-pushed the present branch 2 times, most recently from 26f5b15 to a98d215 Compare January 13, 2026 00:53

marcoscaceres marked this pull request as ready for review January 13, 2026 12:51

marcoscaceres requested a review from a team as a code owner January 13, 2026 12:51

marcoscaceres changed the title ~~Define "Present credential requests" algorithm.~~ Define "present credential requests" algorithm. Jan 13, 2026

marcoscaceres mentioned this pull request Jan 13, 2026

Digital Credential: CredentialRequestCoordinator can remain non-Idle if AbortSignal races with picker result WebKit/WebKit#56489

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WIP Fix Screen Wake Lock in Site Isolation WebKit/WebKit#57011

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Apply suggestions from code review

c3ff7f9

Co-authored-by: Mohamed Amir Yosef <mohamed.amir@gmail.com> Co-authored-by: Ted Thibodeau Jr <tthibodeau@openlinksw.com>

marcoscaceres mentioned this pull request Apr 29, 2026

Include the requesting document's origin in the request context #504

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marcoscaceres requested a review from mohamedamir April 29, 2026 11:38

Merge branch 'main' into present

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Add UI process gesture verification step #506

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editorial: rename "present the credential request" to "initiate the c…

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…redential request" Agent-Logs-Url: https://github.com/w3c-fedid/digital-credentials/sessions/727fd1f7-e1e3-48d7-a636-a4c14b7590a1 Co-authored-by: marcoscaceres <870154+marcoscaceres@users.noreply.github.com>

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Co-authored-by: Mohamed Amir Yosef <mamir@chromium.org>

marcoscaceres merged commit 0bbd3e3 into main Apr 30, 2026
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github-actions Bot added a commit that referenced this pull request Apr 30, 2026

Define "present credential requests" algorithm. (#419)

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SHA: 0bbd3e3 Reason: push, by marcoscaceres Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

marcoscaceres mentioned this pull request Apr 30, 2026

Manage abort signal's lifecycle #460

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marcoscaceres commented Dec 16, 2025 • edited by pr-preview Bot Loading Uh oh! There was an error while loading. Please reload this page.

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What the algorithm does

New terms introduced

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hlflanagan commented Jan 22, 2026

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