docs: add Enterprise SSO guide for SSO administrators

[sea-snake]

Internet Identity can authenticate an organization's staff against its own OpenID provider, but nothing in the docs described how to set that up. Adds a guide for the SSO administrator, and the application developer's half to the existing Internet Identity page.

New page: Single sign-on

docs/guides/authentication/single-sign-on.md, order: 2, so it sits directly after Internet Identity in the Authentication group (Verifiable credentials moves to order: 3).

Follows an existing internal one-pager, and stays at that level of detail:

• Switch on SSO for the organization (required, one time): register an OIDC client, then publish /.well-known/ii-openid-configuration on the company domain.
• Control access per application (optional, per app): a second client, the provider-side assignment that acts as the access rule, and one app_clients line.
• The complete file, with the per-app fields, hiding an app name behind a salted hash, and gate_all_apps.

Internet Identity page

Adds ### One-click SSO sign-in after the existing OpenID section (ssoDomain, mutual exclusivity with openIdProvider, and isValidSsoDomain with its abort and timing behaviour), a #### SSO-scoped attributes subsection, and a Next steps link to the new page.

Verification

The field names, the app_clients key forms, and the gate_all_apps behaviour are checked against the Internet Identity implementation. internet-identity is not among the .sources/ submodules, so the page cites the upstream path it tracks in a trailing comment.

The identity-provider-specific setting (the Entra ID note) cannot be verified from ICP sources and carries a Needs human verification comment.

npm run build passes, and both pages render.

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[Copilot]

Pull request overview

Adds administrator-facing documentation for configuring Internet Identity single sign-on (SSO) via an organization’s OpenID Connect provider, and updates the existing Internet Identity guide with the corresponding application-side integration details. Also adjusts sidebar ordering so the new guide sits next to the existing authentication docs.

Changes:

• Added a new SSO guide covering OIDC client setup, the /.well-known/ii-openid-configuration discovery file, per-app access control, and troubleshooting.
• Updated the Internet Identity guide with ssoDomain usage, isValidSsoDomain, and SSO-scoped attribute key examples.
• Moved “Verifiable credentials” down one slot in the Authentication sidebar order.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
docs/guides/authentication/verifiable-credentials.md	Updates sidebar ordering to make room for the new SSO guide.
docs/guides/authentication/single-sign-on.md	New administrator-focused SSO setup guide (OIDC client + discovery file + optional per-app access control).
docs/guides/authentication/internet-identity.mdx	Adds application-side “one-click SSO sign-in” and SSO-scoped attribute documentation, plus Next steps link.

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[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated no new comments.

Suppressed comments (4)

docs/guides/authentication/internet-identity.mdx:161

• The docs assert a precise timing guarantee ("never resolves in under 750 ms"). That kind of implementation detail is brittle and can become incorrect across SDK versions. Consider describing the behavior without hard-coding a minimum duration.

Call `controller.abort()` when the input changes. An aborted check rejects instead of returning `false`, so a superseded check is never read as an invalid domain. The check also never resolves in under 750 ms, which keeps a partially typed domain from flashing an error on every keystroke.

docs/guides/authentication/single-sign-on.md:22

• The navigation path "Create App Integration → OIDC → Web Application" is Okta-specific UI wording, but the guide is written as if it applies to any IdP. Consider making the instruction generic and optionally calling out Okta as an example so Entra/other IdPs aren’t misled.

Create App Integration → **OIDC** → **Web Application**.

docs/guides/authentication/internet-identity.mdx:134

• This sentence says nothing has to be registered on either side, but the SSO flow still requires the organization to register an OIDC client in its IdP. Reword to avoid contradicting the new SSO admin guide and to clarify that it’s the application that does not need a client registration with the org’s IdP.

To send the user to their organization's own OpenID provider instead, pass `ssoDomain` with the organization's domain. Internet Identity resolves the provider from a configuration file the organization publishes on that domain, so nothing has to be registered on either side:

docs/guides/authentication/internet-identity.mdx:148

• This snippet creates a new AuthClient, but only imports isValidSsoDomain. Readers copying the snippet will hit a missing import for AuthClient; either include it here or remove the import line entirely.

import { isValidSsoDomain } from "@icp-sdk/auth/client";

[marc0olo]

Review: Enterprise SSO

Verified against .sources/internetidentity at release-2026-08-07 (c78d1b99), the pin main picked up in #341.

Must fix

• Sidebar order collision: the new page sets order: 2, and docs/guides/authentication/verifiable-credentials.md already uses order: 2. The PR description claims VC moves to order: 3, but the diff never touches it. Bump VC to 3.

• Config changes are not immediate, and the page never says so: discovery entries cache for one hour (FRESH_FOR_SECONDS, sso.rs:72), with another hour of stale-if-error fallback (STALE_FOR_SECONDS, sso.rs:75). On a page whose central promise is gating access app by app, an admin will assume that removing an app_clients entry revokes access at once. It can take up to an hour, or two if a refetch fails. This belongs in step 3.

• A gated app cannot be a user's first sign-in: resolve_gated_ii_client_sub returns None (surfacing as NoSuchAnchor) unless an identity was already established through the org's II client on that domain. sso_gating.rs:163 says it outright: "sign in normally first." A new employee sent straight to a gated app fails, with no explanation in this guide.

• Out-of-bounds values reject the whole file, not just the field: more than 100 app_clients entries (MAX_APP_CLIENTS, sso.rs:48, rejected rather than truncated, deliberately), a session_max_age_seconds of 0 or above 2592000, or a file over 64 KiB (DISCOVERY_MAX_RESPONSE_BYTES, sso.rs:94) all make validate_ii_config fail, which takes SSO down for the entire domain. The guide presents the 30-day figure as a ceiling, which reads as "it clamps." It does not. One sentence per limit, plus the 100-entry cap, which is not mentioned at all.

• PR description does not match the PR: it names the file single-sign-on.md (it is enterprise-sso.md), claims a Verifiable credentials reorder that is absent, and states that internet-identity is not among the .sources/ submodules when .sources/internetidentity exists and is pinned. It also carries an AI attribution line, which the repo rules ban.

Suggestions

• Say what a domain may look like: validate_discovery_domain (sso.rs:378) requires a bare authority that round-trips exactly through the URL parser (is_bare_authority, sso.rs:400), so https://acme.com, acme.com/, and Acme.com are all rejected. The guide says "enter acme.com" without signalling that this is a constraint rather than a formatting choice.

• app_clients keys are exact origins: matching is byte-equality against the app's origin, so a trailing slash, a path, or a scheme mismatch silently falls through to the org-wide client. The failure is invisible, so it deserves a line.

• Explain why the CORS header is needed: Access-Control-Allow-Origin: * matters only for the client-side pre-check. The canister fetches the file via HTTPS outcalls and is unaffected. As written, an admin may believe SSO breaks without it.

• Caution on changing stable_identifier_claim later: it changes how identities key onto anchors, so flipping it on a live domain is a migration, not a config tweak. Worth confirming the intended behaviour before wording it.

• Anchor the cross-link: Next steps points at internet-identity.md bare. internet-identity.md#one-click-sso-sign-in lands on the half that answers "how do applications send users into this flow."

• Numbering vs the intro: "Setup is two steps" followed by headings 1., 2., 3. reads slightly against itself. "Two required steps, plus an optional third" would remove the stumble.

Verified

• Neither file is on a sync path. sync-ii-spec.yml writes only docs/references/internet-identity-spec.md, docs/references/verifiable-credentials-spec.md, and public/references/internet-identity.did.
• Field names, defaults, and semantics against sso.rs and sso_gating.rs: client_id, openid_configuration, name (falls back to the domain), app_clients, gate_all_apps, stable_identifier_claim (default sub), session_max_age_seconds (default 8h via DEFAULT_SESSION_MAX_AGE_NS, ceiling delegation::MAX_EXPIRATION_PERIOD_NS = 30 days).
• The salted-hash recipe: sha256(origin || salt) with the salt hashed as its hex string, keyed as <hex>:<hex>, cleartext and hashed keys mixable in one file. The shell snippet produces exactly what AppClientKey::parse accepts.
• OIDC client settings: response_type=code id_token with response_mode=form_post, no access token, redirect https://id.ai/callback, default scopes openid/profile/email.
• sso:<domain>:<key> attribute keys, and that verified_email is deliberately unavailable under sso: (attributes.rs:468), matching the page's reasoning.
• session_max_age_seconds is live on mainnet: proposal 143403 executed 2026-08-10, module f6c0abac... = release-2026-08-07.
• Style rules: no em-dashes, no dfx, no mo:base, no absolute internal links, .md extensions, complete frontmatter, ## Next steps present. All three links resolve.

One release-state note

The internet-identity.mdx additions (ssoDomain, isValidSsoDomain, scopedKeys({ ssoDomain })) come from dfinity/icp-js-auth#141, which is still open. The latest published @icp-sdk/auth is 8.0.3 and exposes none of them: scopedKeys accepts only openIdProvider. The canister half of this PR is fully live, so that section is the only part gated on an external release.