Sign-in: Ring and Bitkit QRs side by side, profile prefill, clear quota error

[BitcoinErrorLog]

#48: new Bitkit identities on the Shop (profile save, both QRs, profile prefill)

Base: release/shop-v0.6.8 @ 5e7fc0e64 (tag shop-v0.6.25). Issue: BitcoinErrorLog/pubky-marketplace#48 (comment)

Root cause of "Could not save profile" (not a Shop or SDK defect)

The production homeserver refuses every pubky.app write for accounts created through Homegate's IP signup, which is how Bitkit creates an identity (PubkyRepo.createIdentity → POST https://homegate.pubky.app/ip_verification → signUp). Homegate gives those accounts allowed_write_paths = ["/pub/paykit/", "/pub/bitkit.to/"] and a 2 MB storage quota (pubky/pubky-stack .github/workflows/homegate-cicd.yml:110-116). The homeserver's WritePathLayer then answers 403 Write to this path is not allowed for /pub/pubky.app/* and /priv/pubky.app/*, whatever the session's capabilities.

Evidence, production, throwaway Homegate IP-signup identity 5dyqcwcn…:

• shop.pubky.app v0.6.25 in Chromium: grant sign-in succeeds (POST /auth/grant/session 200), PUT /pub/pubky.app/profile.json → 403 Write to this path is not allowed, toast "Could not save profile". Pav's failure reproduced.
• A root cookie session (/:rw) for the same account gets the same 403 on /pub/pubky.app/profile.json, /pub/pubky.app/marketplace/v1/… and /priv/pubky.app/…, while /pub/paykit/ and /pub/bitkit.to/ succeed.
• The Shop's grant session (startGrantAuthFlow(CAPABILITIES, signin, cid shop.pubky.app), SDK 0.11) for the seller test seat n3pfudgx… writes, reads back and deletes /pub/pubky.app/proofs/…. The grant session storage API and the capability path are correct; only the account allow-list differs.

The Shop cannot lift that restriction. This PR makes the Shop say what happened and fixes the two UX problems. The homeserver-side fix is an operator change in pubky/pubky-stack (see "Needs an owner decision").

Changes

1. Both QRs on /sign-in. Ring and Bitkit QRs render side by side, each labelled ("Pubky Ring" / "Bitkit", "Scan with Bitkit 2.5 or newer."); mobile shows both Authorize buttons. The Bitkit grant flow gets its own controller slot, so it no longer cancels the Ring single-approval ceremony. A completed sign-in, local-state cleanup and cross-tab sign-out cancel both. A Bitkit approval that settles after another sign-in won is signed out, not initialized. The Ring QR URL and its dual POST are unchanged. Browsers without grant delegation keep the Ring-only layout.
2. Accurate save error. isWritePathNotAllowedError matches the homeserver's allow-list 403 body; Create profile shows "Your homeserver account doesn't allow saving a Pubky profile yet. Signing in again won't change this." A capability 403 keeps "Could not save profile".
3. Prefill, no invented name. Create profile reads the account's Pubky App profile.json, then Bitkit's profile (Paykit rc55 /pub/bitkit.to/bitkit/wallet/profile.json, then the Bitkit 2.4 /pub/bitkit.to/profile.json), and prefills name, bio and safe links without overwriting typing. With no profile the name is empty. An existing Pubky App profile.json still skips onboarding (unchanged userIsSignedUp). generateRandomUsername had no other caller and is removed.

§6d contract table

#	Input or state	Deployed client / current behaviour	New behaviour	UI copy or state	Test name
S1	/sign-in, no grant delegation	Ring QR only	unchanged	Ring QR only	bitkit qr hidden without delegation
S2	/sign-in, grant delegation available	Ring QR; Bitkit QR behind "Signing in with Bitkit? Use Bitkit instead"	Ring and Bitkit QRs side by side, labelled; no switch link	"Authorize with Pubky Ring or Bitkit to sign in."	shows the Ring and Bitkit QRs side by side, each labelled, with no link to click
S3	Ring QR URL	pubkyauth://signin?caps&relay&secret	unchanged	unchanged	Chromium ring-with-both-qrs-proof.mjs check 2; existing R1.1 tests
S4	Bitkit flow starts while the Ring ceremony is live (and the reverse)	Bitkit start cancels the Ring ceremony (single slot)	both stay live	both QRs scannable	starting the Bitkit QR keeps the Ring ceremony live, starting the Ring QR keeps the Bitkit flow live
S5	Any sign-in completes, cleanup, cross-tab sign-out	cancels the one live flow	cancels both, bumps the flow generation	progress view	a completed sign-in cancels both QRs
S6	Bitkit approval settles after another sign-in or a sign-out	n/a (one flow)	grant session signed out, rejected as canceled; signed-in identity untouched	none	a Bitkit approval that settles after another sign-in won is signed out, not returned; positive a Bitkit approval with no competing sign-in is returned
S7	Hook releases its Bitkit handle	cancels the single slot	cancels only the Bitkit slot	Ring QR stays	releasing the Bitkit handle cancels only the Bitkit flow
S8	Mobile /sign-in	"Authorize with Pubky Ring" + text link	both Authorize buttons	"Authorize with Pubky Ring", "Authorize with Bitkit"	offers both authorize buttons on mobile
S9	Copy on the Bitkit QR	n/a	copies the Bitkit flow URL	"Authentication link copied"	copying the Bitkit QR copies the Bitkit flow URL, not the Ring one
E1	Homeserver 403 Write to this path is not allowed on profile save	"Could not save profile"	account-restriction copy	"Your homeserver account doesn't allow saving a Pubky profile yet. Signing in again won't change this."	the account allow-list 403 maps to an auth error the profile form can name, names the homeserver account restriction when the profile write is refused by path
E2	Homeserver capability 403	"Could not save profile"	unchanged	"Could not save profile"	a capability 403 is not reported as an account restriction, keeps the generic copy for other homeserver 403s
E3	401 / session expired	"Session expired. Please sign in."	unchanged	unchanged	existing useProfileForm / error tests
P1	Pubky App profile.json exists at sign-in	onboarding skipped (userIsSignedUp)	unchanged; if Create profile is reached, it prefills from it first	—	prefers an existing Pubky App profile
P2	No Pubky App profile, Bitkit rc55 profile	random name ("Dusty-Dolphin-Shield")	name, bio, safe links prefilled	prefilled form	falls back to the Bitkit profile, newest layout first, prefills name, bio and links from an existing profile; Chromium check 6
P3	Only the Bitkit 2.4 layout	random name	prefilled	prefilled form	reads the Bitkit 2.4 layout when only it exists
P4	No profile anywhere	random name	empty name, Finish disabled until typed	placeholder "Enter your name"	does not invent a name when the account has no profile; Chromium check 6 (no-profile run); VRT onboarding-profile-*
P5	Malformed or wrong-typed profile JSON, javascript: links	n/a	fields ignored, unsafe links dropped, values bounded to spec limits	—	ignores fields of the wrong type instead of failing, takes the name, bio and safe links from a Bitkit profile, bounds every field to the Pubky App limits
P6	Profile read fails	n/a	next source; never rejects; log carries path and error code only	form as P4	never rejects: a failed read moves on to the next source
P7	User types before the prefill arrives	n/a	typed value kept	—	never overwrites a name typed before the profile arrives
P8	Edit profile	n/a	no prefill read	—	edit mode never reads a prefill

Identity predicates: S6 compares nothing new; the signed-in identity is still decided by completeAuthenticatedSession → persistIdentityUnderLock (shouldAbortIdentityPersist against currentUserPubky and the persisted blob). Residual (P3 cleanup): if a Ring token was already redeemed when a Bitkit completion cancels the Ring flow, a later Ring completion for a different pubky is refused by that guard; for the same pubky it replaces the grant session and the grant record stays in IndexedDB until the next sign-out's clearAll.

The Bitkit profile fixture is authored from pubky/paykit-rs v0.1.0-rc55 PaykitProfile serde and bitkit-android PubkyProfileData; no live Bitkit-written profile has been captured yet. Parsing is tolerant (.passthrough(), every field optional).

Proof

• Pre-push gate: PREPUSH OK 22e5d08862bf345050d660cb834f5289c91e4312 403 (prettier and eslint on 21/19 changed files, typecheck, vitest related 708 files / 10,814 tests, Linux VRT 62 specs: 98 + 26 files passed).
• Real Chromium on head 22e5d088, local build of this branch against the production homeserver, relay, Nexus and marketplace service, throwaway Homegate IP-signup identity: both QRs visible without a click; Bitkit grant approval signs in; Create profile shows an empty name (no profile) or the Bitkit name and bio (after writing a Bitkit rc55 profile); save shows the account-restriction copy on the homeserver's 403.
• Real Chromium, same build, seller test seat: Ring approval with both QRs live → one POST /session 200, one marketplace POST /v1/auth/sessions 201, cookie export, no grant exchange; signed out after.
• Mutation calibration: each new controller, seed and hook gate fails on a deliberate regression; the VRT baseline fails on a one-byte change.

Needs an owner decision (outside this repo)

Bitkit-created identities stay unable to save a Shop profile, publish listings, or write the purchase-bootstrap proof document until pubky/pubky-stack adds /pub/pubky.app/ to the production ip_verification.signup_quota.allowed_write_paths and existing Homegate IP accounts get the same quota update on the homeserver.