Complete passkey recovery transaction

CHANGELOG.md

@@ -2,6 +2,18 @@
 
 # Changelog
 
+## v0.1.0-preview.13 — 2026-09-03
+
+- Complete the password-plus-recovery-code flow with a short-lived restricted
+  grant bound into a replacement-passkey ceremony. Completion atomically
+  consumes the grant, stores the verified passkey, replaces every recovery
+  code, revokes any intervening sessions and ceremonies, and records both
+  audits without issuing a normal session.
+- Keep failed completion retryable until grant expiry: a duplicate credential
+  or other transaction failure rolls back grant consumption and recovery-code
+  replacement, while a mismatched WebAuthn binding consumes only the affected
+  ceremony.
+
 ## v0.1.0-preview.12 — 2026-09-03
 
 - Add a root-local bootstrap transaction that creates the first passkey-only

README.md

@@ -17,7 +17,7 @@ router, handlers, HTML, authorization decisions, cache behavior, and
 deployment. Adopt one boundary at a time; Go compiles and links only the
 packages you import.
 
-> **Public preview:** `v0.1.0-preview.12`. APIs may change before a stable
+> **Public preview:** `v0.1.0-preview.13`. APIs may change before a stable
 > release. Linux is the maintained release platform.
 
 ## Why Web Foundations?
@@ -57,14 +57,14 @@ owns—and, just as importantly, what remains application policy.
 Pin the preview in an application module:
 
 ```bash
-go get gamertan.com/web@v0.1.0-preview.12
+go get gamertan.com/web@v0.1.0-preview.13
 go mod verify
 ```
 
 An application may name the first package it intends to adopt:
 
 ```bash
-go get gamertan.com/web/requestmeta@v0.1.0-preview.12
+go get gamertan.com/web/requestmeta@v0.1.0-preview.13
 ```
 
 The version belongs to the `gamertan.com/web` module. See the

authrecovery/recovery.go

@@ -17,6 +17,7 @@ import (
 	"time"
 
 	"gamertan.com/web/auth"
+	"gamertan.com/web/authwebauthn"
 )
 
 const DefaultCodeCount = 10
@@ -24,6 +25,7 @@ const DefaultCodeCount = 10
 var (
 	ErrCodeNotFound       = errors.New("authrecovery: recovery code not found")
 	ErrGrantNotFound      = errors.New("authrecovery: recovery grant not found")
+	ErrPasskeyUnavailable = errors.New("authrecovery: passkey recovery is unavailable")
 )
 
 type Grant struct {
@@ -39,6 +41,38 @@ type Repository interface {
 	TakeRecoveryGrant(context.Context, [32]byte, time.Time) (auth.User, error)
 }
 
+// PasskeyRepository adds the transactional boundary required to finish a
+// password-plus-recovery-code flow without issuing a normal session.
+type PasskeyRepository interface {
+	Repository
+	RecoveryGrant(context.Context, [32]byte, time.Time) (auth.User, error)
+	CompletePasskeyRecovery(context.Context, PasskeyCompletion) error
+}
+
+// Passkeys performs recovery-bound WebAuthn registration ceremonies.
+type Passkeys interface {
+	BeginRecoveryRegistration(context.Context, string, string, []byte) (authwebauthn.BeginResult, error)
+	FinishRecoveryRegistration(context.Context, string, []byte, []byte, authwebauthn.RegistrationCommit) (authwebauthn.Credential, error)
+}
+
+// PasskeyCompletion contains the public credential, digest-only replacement
+// codes, and secret-free audits committed after a recovery ceremony.
+type PasskeyCompletion struct {
+	GrantDigest     [32]byte
+	Credential      authwebauthn.Credential
+	RecoveryDigests [][32]byte
+	PasskeyAudit    auth.AuditEvent
+	RecoveryAudit   auth.AuditEvent
+	CompletedAt     time.Time
+}
+
+// PasskeyFinishResult returns the verified credential and the new plaintext
+// recovery codes. Applications must display the codes once and retain none.
+type PasskeyFinishResult struct {
+	Credential    authwebauthn.Credential
+	RecoveryCodes []string
+}
+
 type PasswordVerifier interface {
 	VerifyPassword(context.Context, string, string) (auth.User, error)
 }
@@ -48,6 +82,7 @@ type Options struct {
 	Now           func() time.Time
 	CodeCount     int
 	GrantLifetime time.Duration
+	Passkeys      Passkeys
 }
 
 type Service struct {
@@ -57,6 +92,7 @@ type Service struct {
 	now        func() time.Time
 	count      int
 	grantTTL   time.Duration
+	passkeys   Passkeys
 }
 
 func New(repository Repository, passwords PasswordVerifier, options Options) (*Service, error) {
@@ -78,7 +114,7 @@ func New(repository Repository, passwords PasswordVerifier, options Options) (*S
 	if options.CodeCount < 5 || options.CodeCount > 20 || options.GrantLifetime < 2*time.Minute || options.GrantLifetime > 30*time.Minute {
 		return nil, errors.New("authrecovery: invalid recovery policy")
 	}
-	return &Service{repository: repository, passwords: passwords, random: options.Random, now: options.Now, count: options.CodeCount, grantTTL: options.GrantLifetime}, nil
+	return &Service{repository: repository, passwords: passwords, random: options.Random, now: options.Now, count: options.CodeCount, grantTTL: options.GrantLifetime, passkeys: options.Passkeys}, nil
 }
 
 // ReplaceCodes creates a complete new recovery-code set. Codes are returned
@@ -133,10 +169,74 @@ func (service *Service) Begin(ctx context.Context, identifier, password, code st
 }
 
 func (service *Service) TakeGrant(ctx context.Context, raw string) (auth.User, error) {
-	if len(raw) < 32 || len(raw) > 128 {
+	digest, err := grantDigest(raw)
-		return auth.User{}, ErrGrantNotFound
+	if err != nil {
+		return auth.User{}, err
 	}
-	return service.repository.TakeRecoveryGrant(ctx, sha256.Sum256([]byte(raw)), service.now().UTC())
+	return service.repository.TakeRecoveryGrant(ctx, digest, service.now().UTC())
+}
+
+// BeginPasskey starts a ceremony only for a live restricted recovery grant.
+// The raw grant remains application-held so a failed or interrupted ceremony
+// can be restarted until the grant expires.
+func (service *Service) BeginPasskey(ctx context.Context, rawGrant, label string) (authwebauthn.BeginResult, error) {
+	repository, ok := service.repository.(PasskeyRepository)
+	if !ok || service.passkeys == nil {
+		return authwebauthn.BeginResult{}, ErrPasskeyUnavailable
+	}
+	digest, err := grantDigest(rawGrant)
+	if err != nil {
+		return authwebauthn.BeginResult{}, err
+	}
+	user, err := repository.RecoveryGrant(ctx, digest, service.now().UTC())
+	if err != nil {
+		return authwebauthn.BeginResult{}, err
+	}
+	return service.passkeys.BeginRecoveryRegistration(ctx, user.ID, label, []byte(rawGrant))
+}
+
+// FinishPasskey consumes the grant only inside the transaction that stores the
+// verified passkey and a fresh recovery-code set. It never issues a session.
+func (service *Service) FinishPasskey(ctx context.Context, rawGrant, ceremonyToken string, response []byte) (PasskeyFinishResult, error) {
+	repository, ok := service.repository.(PasskeyRepository)
+	if !ok || service.passkeys == nil {
+		return PasskeyFinishResult{}, ErrPasskeyUnavailable
+	}
+	digest, err := grantDigest(rawGrant)
+	if err != nil {
+		return PasskeyFinishResult{}, err
+	}
+	user, err := repository.RecoveryGrant(ctx, digest, service.now().UTC())
+	if err != nil {
+		return PasskeyFinishResult{}, err
+	}
+	codes, digests, err := GenerateCodeSet(service.random, service.count)
+	if err != nil {
+		return PasskeyFinishResult{}, err
+	}
+	credential, err := service.passkeys.FinishRecoveryRegistration(ctx, ceremonyToken, []byte(rawGrant), response, func(commitContext context.Context, verified authwebauthn.Credential, passkeyAudit auth.AuditEvent) error {
+		if verified.UserID != user.ID {
+			return errors.New("authrecovery: recovery identity mismatch")
+		}
+		completedAt := service.now().UTC()
+		auditID, auditErr := token(service.random, 18)
+		if auditErr != nil {
+			return auditErr
+		}
+		recoveryAudit := auth.AuditEvent{ID: auditID, ActorUserID: user.ID, Action: "auth.recovery.complete", ResourceType: "user", ResourceID: user.ID, Summary: "Account recovery enrolled a replacement passkey and replaced the recovery-code set.", CreatedAt: completedAt}
+		return repository.CompletePasskeyRecovery(commitContext, PasskeyCompletion{
+			GrantDigest:     digest,
+			Credential:      verified,
+			RecoveryDigests: digests,
+			PasskeyAudit:    passkeyAudit,
+			RecoveryAudit:   recoveryAudit,
+			CompletedAt:     completedAt,
+		})
+	})
+	if err != nil {
+		return PasskeyFinishResult{}, err
+	}
+	return PasskeyFinishResult{Credential: credential, RecoveryCodes: codes}, nil
 }
 
 func GenerateCodeSet(random io.Reader, count int) ([]string, [][32]byte, error) {
@@ -173,6 +273,16 @@ func DigestCode(code string) ([32]byte, error) {
 	return sha256.Sum256(append([]byte("gamertan-web-recovery-code-v1\x00"), decoded...)), nil
 }
 
+func grantDigest(raw string) ([32]byte, error) {
+	if len(raw) < 32 || len(raw) > 128 {
+		return [32]byte{}, ErrGrantNotFound
+	}
+	if _, err := base64.RawURLEncoding.DecodeString(raw); err != nil {
+		return [32]byte{}, ErrGrantNotFound
+	}
+	return sha256.Sum256([]byte(raw)), nil
+}
+
 func token(random io.Reader, size int) (string, error) {
 	value := make([]byte, size)
 	if _, err := io.ReadFull(random, value); err != nil {

authrecovery/recovery_test.go

@@ -3,6 +3,10 @@
 package authrecovery_test
 
 import (
+	"bytes"
+	"context"
+	"encoding/base64"
+	"encoding/json"
 	"errors"
 	"path/filepath"
 	"strings"
@@ -12,6 +16,8 @@ import (
 	"gamertan.com/web/auth"
 	"gamertan.com/web/authrecovery"
 	"gamertan.com/web/authsqlite"
+	"gamertan.com/web/authwebauthn"
+	wa "gamertan.com/web/internal/webauthnvendored/webauthn"
 )
 
 func TestRecoveryCodeIsSingleUseAndRevokesSessions(t *testing.T) {
@@ -61,6 +67,112 @@ func TestRecoveryCodeIsSingleUseAndRevokesSessions(t *testing.T) {
 	}
 }
 
+func TestPasskeyRecoveryAtomicallyReplacesCodesWithoutIssuingSession(t *testing.T) {
+	now := time.Date(2026, 9, 3, 13, 0, 0, 0, time.UTC)
+	store, err := authsqlite.Open(filepath.Join(t.TempDir(), "accounts.db"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer store.Close()
+	random := &counterReader{}
+	authService, err := auth.New(store, auth.Options{Random: random, Now: func() time.Time { return now }})
+	if err != nil {
+		t.Fatal(err)
+	}
+	user, err := authService.CreateUser(t.Context(), auth.CreateUser{Username: "recover.passkey", Email: "recover-passkey@example.test", DisplayName: "Recover Passkey", Password: "correct horse battery staple"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	existingID := bytes.Repeat([]byte{7}, 32)
+	existingJSON, err := json.Marshal(wa.Credential{ID: existingID, PublicKey: []byte{1, 2, 3}})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err = store.SaveCredential(t.Context(), authwebauthn.Credential{ID: existingID, UserID: user.ID, Label: "Existing passkey", Data: existingJSON, CreatedAt: now}, auth.AuditEvent{ID: "existing-passkey-audit", ActorUserID: user.ID, Action: "auth.passkey.add", ResourceType: "passkey", ResourceID: base64.RawURLEncoding.EncodeToString(existingID), Summary: "Existing passkey fixture.", CreatedAt: now}); err != nil {
+		t.Fatal(err)
+	}
+	passkeys := &passkeyRecoveryStub{now: now, credentialID: existingID}
+	recovery, err := authrecovery.New(store, authService, authrecovery.Options{Random: random, Now: func() time.Time { return now }, Passkeys: passkeys})
+	if err != nil {
+		t.Fatal(err)
+	}
+	oldCodes, err := recovery.ReplaceCodes(t.Context(), user.ID, user.ID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, grant, err := recovery.Begin(t.Context(), user.Email, "correct horse battery staple", oldCodes[0])
+	if err != nil {
+		t.Fatal(err)
+	}
+	begin, err := recovery.BeginPasskey(t.Context(), grant, "Replacement passkey")
+	if err != nil || begin.CeremonyToken == "" || passkeys.userID != user.ID || passkeys.beginBinding != grant {
+		t.Fatalf("begin=%+v passkeys=%+v err=%v", begin, passkeys, err)
+	}
+	if _, err = recovery.FinishPasskey(t.Context(), grant, begin.CeremonyToken, []byte(`{"fixture":true}`)); err == nil {
+		t.Fatal("duplicate credential unexpectedly committed")
+	}
+	if _, err = recovery.BeginPasskey(t.Context(), grant, "Retry replacement"); err != nil {
+		t.Fatalf("failed completion consumed recovery grant: %v", err)
+	}
+	lateSession, _, err := authService.IssueSession(t.Context(), user.ID, time.Hour)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	passkeys.credentialID = bytes.Repeat([]byte{8}, 32)
+	result, err := recovery.FinishPasskey(t.Context(), grant, "retry-ceremony-token", []byte(`{"fixture":true}`))
+	if err != nil || len(result.RecoveryCodes) != authrecovery.DefaultCodeCount || !bytes.Equal(result.Credential.ID, passkeys.credentialID) {
+		t.Fatalf("result=%+v err=%v", result, err)
+	}
+	if passkeys.finishBinding != grant {
+		t.Fatal("finish ceremony was not bound to the restricted recovery grant")
+	}
+	if _, err = recovery.TakeGrant(t.Context(), grant); !errors.Is(err, authrecovery.ErrGrantNotFound) {
+		t.Fatalf("completed grant replay err=%v", err)
+	}
+	if _, err = authService.Session(t.Context(), lateSession); !errors.Is(err, auth.ErrSessionNotFound) {
+		t.Fatalf("session created during recovery survived completion: %v", err)
+	}
+	if _, _, err = recovery.Begin(t.Context(), user.Email, "correct horse battery staple", oldCodes[1]); !errors.Is(err, auth.ErrInvalidCredentials) {
+		t.Fatalf("old recovery-code set survived completion: %v", err)
+	}
+	if _, newGrant, beginErr := recovery.Begin(t.Context(), user.Email, "correct horse battery staple", result.RecoveryCodes[0]); beginErr != nil || newGrant == "" {
+		t.Fatalf("new recovery code unavailable: grant=%q err=%v", newGrant, beginErr)
+	}
+	credentials, err := store.CredentialsByUserID(t.Context(), user.ID)
+	if err != nil || len(credentials) != 2 {
+		t.Fatalf("credentials=%+v err=%v", credentials, err)
+	}
+}
+
+type passkeyRecoveryStub struct {
+	now           time.Time
+	userID        string
+	credentialID  []byte
+	beginBinding  string
+	finishBinding string
+}
+
+func (stub *passkeyRecoveryStub) BeginRecoveryRegistration(_ context.Context, userID, _ string, binding []byte) (authwebauthn.BeginResult, error) {
+	stub.userID = userID
+	stub.beginBinding = string(binding)
+	return authwebauthn.BeginResult{CeremonyToken: "recovery-ceremony-token", PublicKey: json.RawMessage(`{"challenge":"fixture"}`), ExpiresAt: stub.now.Add(5 * time.Minute)}, nil
+}
+
+func (stub *passkeyRecoveryStub) FinishRecoveryRegistration(ctx context.Context, _ string, binding, _ []byte, commit authwebauthn.RegistrationCommit) (authwebauthn.Credential, error) {
+	stub.finishBinding = string(binding)
+	encoded, err := json.Marshal(wa.Credential{ID: stub.credentialID, PublicKey: []byte{1, 2, 3}})
+	if err != nil {
+		return authwebauthn.Credential{}, err
+	}
+	credential := authwebauthn.Credential{ID: append([]byte(nil), stub.credentialID...), UserID: stub.userID, Label: "Replacement passkey", Data: encoded, CreatedAt: stub.now}
+	audit := auth.AuditEvent{ID: "recovery-passkey-audit", ActorUserID: stub.userID, Action: "auth.recovery.passkey", ResourceType: "passkey", ResourceID: base64.RawURLEncoding.EncodeToString(stub.credentialID), Summary: "A replacement passkey was enrolled during account recovery.", CreatedAt: stub.now}
+	if err = commit(ctx, credential, audit); err != nil {
+		return authwebauthn.Credential{}, err
+	}
+	return credential, nil
+}
+
 type counterReader struct{ value byte }
 
 func (reader *counterReader) Read(target []byte) (int, error) {

authsqlite/recovery.go

@@ -3,8 +3,10 @@
 package authsqlite
 
 import (
+	"bytes"
 	"context"
 	"database/sql"
+	"encoding/base64"
 	"errors"
 	"time"
 
@@ -38,6 +40,100 @@ func (store *Store) ReplaceRecoveryCodes(ctx context.Context, userID string, dig
 	return tx.Commit()
 }
 
+func (store *Store) RecoveryGrant(ctx context.Context, digest [32]byte, now time.Time) (auth.User, error) {
+	if zeroDigest(digest) || now.IsZero() {
+		return auth.User{}, authrecovery.ErrGrantNotFound
+	}
+	user, err := scanPasskeyUser(store.db.QueryRowContext(ctx, `SELECT u.id,u.username,u.email,u.display_name,u.status,u.password_change_required,u.registration_pending,u.created_at,u.updated_at FROM gwf_recovery_grants g JOIN gwf_users u ON u.id=g.user_id WHERE g.token_hash=? AND g.expires_at>?`, digest[:], now.Unix()))
+	if errors.Is(err, auth.ErrUserNotFound) {
+		return auth.User{}, authrecovery.ErrGrantNotFound
+	}
+	return user, err
+}
+
+func (store *Store) CompletePasskeyRecovery(ctx context.Context, completion authrecovery.PasskeyCompletion) error {
+	credential := completion.Credential
+	credentialResource := base64.RawURLEncoding.EncodeToString(credential.ID)
+	if zeroDigest(completion.GrantDigest) || !validCredential(credential, true) || len(completion.RecoveryDigests) < 5 || len(completion.RecoveryDigests) > 20 || completion.CompletedAt.IsZero() || !validAuditEvent(completion.PasskeyAudit) || !validAuditEvent(completion.RecoveryAudit) || completion.PasskeyAudit.ActorUserID != credential.UserID || completion.PasskeyAudit.Action != "auth.recovery.passkey" || completion.PasskeyAudit.ResourceType != "passkey" || completion.PasskeyAudit.ResourceID != credentialResource || completion.RecoveryAudit.ActorUserID != credential.UserID || completion.RecoveryAudit.Action != "auth.recovery.complete" || completion.RecoveryAudit.ResourceType != "user" || completion.RecoveryAudit.ResourceID != credential.UserID {
+		return errors.New("authsqlite: invalid passkey recovery completion")
+	}
+	seen := make(map[[32]byte]struct{}, len(completion.RecoveryDigests))
+	for _, digest := range completion.RecoveryDigests {
+		if zeroDigest(digest) {
+			return errors.New("authsqlite: invalid recovery-code digest")
+		}
+		if _, exists := seen[digest]; exists {
+			return errors.New("authsqlite: duplicate recovery-code digest")
+		}
+		seen[digest] = struct{}{}
+	}
+	tx, err := store.db.BeginTx(ctx, nil)
+	if err != nil {
+		return err
+	}
+	defer tx.Rollback()
+	var userID string
+	err = tx.QueryRowContext(ctx, `DELETE FROM gwf_recovery_grants WHERE token_hash=? AND expires_at>? RETURNING user_id`, completion.GrantDigest[:], completion.CompletedAt.Unix()).Scan(&userID)
+	if errors.Is(err, sql.ErrNoRows) {
+		return authrecovery.ErrGrantNotFound
+	}
+	if err != nil {
+		return err
+	}
+	if userID != credential.UserID {
+		return errors.New("authsqlite: passkey recovery identity mismatch")
+	}
+	var active, pending int
+	if err = tx.QueryRowContext(ctx, `SELECT status='active',registration_pending FROM gwf_users WHERE id=?`, userID).Scan(&active, &pending); err != nil || active != 1 || pending != 0 {
+		if err != nil && !errors.Is(err, sql.ErrNoRows) {
+			return err
+		}
+		return auth.ErrInactiveUser
+	}
+	existing, err := tx.QueryContext(ctx, `SELECT credential_id FROM gwf_passkey_credentials WHERE user_id=?`, userID)
+	if err != nil {
+		return err
+	}
+	for existing.Next() {
+		var id []byte
+		if err = existing.Scan(&id); err != nil {
+			existing.Close()
+			return err
+		}
+		if bytes.Equal(id, credential.ID) {
+			existing.Close()
+			return errors.New("authsqlite: passkey credential already exists")
+		}
+	}
+	if err = existing.Close(); err != nil {
+		return err
+	}
+	if _, err = tx.ExecContext(ctx, `INSERT INTO gwf_passkey_credentials(credential_id,user_id,label,credential_json,created_at,last_used_at) VALUES(?,?,?,?,?,NULL)`, credential.ID, userID, credential.Label, []byte(credential.Data), credential.CreatedAt.Unix()); err != nil {
+		return err
+	}
+	if _, err = tx.ExecContext(ctx, `DELETE FROM gwf_recovery_codes WHERE user_id=?`, userID); err != nil {
+		return err
+	}
+	for _, digest := range completion.RecoveryDigests {
+		if _, err = tx.ExecContext(ctx, `INSERT INTO gwf_recovery_codes(user_id,code_hash,created_at,used_at) VALUES(?,?,?,NULL)`, userID, digest[:], completion.CompletedAt.Unix()); err != nil {
+			return err
+		}
+	}
+	if _, err = tx.ExecContext(ctx, `DELETE FROM gwf_auth_sessions WHERE user_id=?`, userID); err != nil {
+		return err
+	}
+	if _, err = tx.ExecContext(ctx, `DELETE FROM gwf_passkey_ceremonies WHERE user_id=?`, userID); err != nil {
+		return err
+	}
+	if err = appendAudit(ctx, tx, completion.PasskeyAudit); err != nil {
+		return err
+	}
+	if err = appendAudit(ctx, tx, completion.RecoveryAudit); err != nil {
+		return err
+	}
+	return tx.Commit()
+}
+
 func (store *Store) ConsumeRecoveryCodeAndCreateGrant(ctx context.Context, userID string, codeDigest [32]byte, grant authrecovery.Grant, audit auth.AuditEvent) error {
 	if !opaqueID(userID) || zeroDigest(codeDigest) || grant.UserID != userID || zeroDigest(grant.Digest) || grant.CreatedAt.IsZero() || !grant.ExpiresAt.After(grant.CreatedAt) || grant.ExpiresAt.Sub(grant.CreatedAt) > 30*time.Minute || !validAuditEvent(audit) || audit.ResourceID != userID {
 		return errors.New("authsqlite: invalid recovery attempt")

authwebauthn/service.go

@@ -218,6 +218,23 @@ func (service *Service) BeginAccountRegistration(ctx context.Context, userID, la
 	return service.beginRegistration(ctx, user, label, CeremonyRegistration, BindingDigest(binding), true)
 }
 
+// BeginRecoveryRegistration starts a replacement-passkey ceremony bound to a
+// short-lived recovery grant selected by the application. The grant itself is
+// never persisted in ceremony state; only its digest is retained.
+func (service *Service) BeginRecoveryRegistration(ctx context.Context, userID, label string, binding []byte) (BeginResult, error) {
+	if len(binding) < 16 || len(binding) > 4096 {
+		return BeginResult{}, ErrOperationBinding
+	}
+	user, err := service.repository.UserByID(ctx, strings.TrimSpace(userID))
+	if err != nil {
+		return BeginResult{}, err
+	}
+	if user.RegistrationPending || user.Status != "active" {
+		return BeginResult{}, auth.ErrInactiveUser
+	}
+	return service.beginRegistration(ctx, user, label, CeremonyRegistration, BindingDigest(binding), false)
+}
+
 // BeginPasswordMigration starts registration for an already authenticated
 // password-backed user. Completion atomically retires the password and revokes
 // all sessions, including the session that authorized this ceremony.
@@ -289,6 +306,20 @@ func (service *Service) FinishAccountRegistration(ctx context.Context, ceremonyT
 	return service.finishRegistration(ctx, ceremonyToken, CeremonyRegistration, "", BindingDigest(binding), response, false, true, commit)
 }
 
+// FinishRecoveryRegistration verifies a replacement passkey and delegates its
+// persistence to commit so recovery-grant consumption, credential storage, and
+// recovery-code replacement can share one transaction.
+func (service *Service) FinishRecoveryRegistration(ctx context.Context, ceremonyToken string, binding, response []byte, commit RegistrationCommit) (Credential, error) {
+	if len(binding) < 16 || len(binding) > 4096 || commit == nil {
+		return Credential{}, ErrOperationBinding
+	}
+	return service.finishRegistration(ctx, ceremonyToken, CeremonyRegistration, "", BindingDigest(binding), response, false, false, func(commitContext context.Context, credential Credential, audit auth.AuditEvent) error {
+		audit.Action = "auth.recovery.passkey"
+		audit.Summary = "A replacement passkey was enrolled during account recovery."
+		return commit(commitContext, credential, audit)
+	})
+}
+
 // FinishPasswordMigration verifies the new passkey and persists it together
 // with password retirement and session revocation in one storage transaction.
 func (service *Service) FinishPasswordMigration(ctx context.Context, ceremonyToken string, response []byte) (Credential, error) {

authwebauthn/service_test.go

@@ -4,6 +4,7 @@ package authwebauthn_test
 
 import (
 	"bytes"
+	"context"
 	"crypto/sha256"
 	"encoding/json"
 	"errors"
@@ -147,6 +148,30 @@ func TestRecoveryRevokesSessionsAndIssuesSingleUseEnrollment(t *testing.T) {
 	}
 }
 
+func TestRecoveryRegistrationIsBoundAndConsumesMismatchedCeremony(t *testing.T) {
+	now := time.Date(2026, 9, 3, 13, 0, 0, 0, time.UTC)
+	store, authService, service := newService(t, &now, &counterReader{})
+	defer store.Close()
+	user, err := authService.CreateUser(t.Context(), auth.CreateUser{Username: "recover.bound", Email: "recover-bound@example.test", DisplayName: "Recover Bound", Password: "correct horse battery staple"})
+	if err != nil {
+		t.Fatal(err)
+	}
+	binding := bytes.Repeat([]byte("restricted recovery grant "), 2)
+	begin, err := service.BeginRecoveryRegistration(t.Context(), user.ID, "Replacement passkey", binding)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err = service.FinishRecoveryRegistration(t.Context(), begin.CeremonyToken, append([]byte(nil), binding[:len(binding)-1]...), []byte(`{}`), func(context.Context, authwebauthn.Credential, auth.AuditEvent) error { return nil }); !errors.Is(err, authwebauthn.ErrOperationBinding) {
+		t.Fatalf("tampered recovery binding err=%v", err)
+	}
+	if _, err = service.FinishRecoveryRegistration(t.Context(), begin.CeremonyToken, binding, []byte(`{}`), func(context.Context, authwebauthn.Credential, auth.AuditEvent) error { return nil }); !errors.Is(err, authwebauthn.ErrCeremonyNotFound) {
+		t.Fatalf("mismatched completion did not consume recovery ceremony: %v", err)
+	}
+	if _, err = service.BeginRecoveryRegistration(t.Context(), user.ID, "Replacement passkey", []byte("short")); !errors.Is(err, authwebauthn.ErrOperationBinding) {
+		t.Fatalf("short recovery binding err=%v", err)
+	}
+}
+
 func TestPasswordMigrationCeremonyIsBoundAndUnavailableAfterRetirement(t *testing.T) {
 	now := time.Date(2026, 8, 27, 12, 0, 0, 0, time.UTC)
 	store, err := authsqlite.Open(t.TempDir() + "/auth.db")

docs/DOGFOOD.md

@@ -43,3 +43,9 @@ application concern belongs in the shared module.
   non-personal organization, membership, direct owner binding, and audits
   together. Applications must seed their owner role first and must write the
   returned raw token only to a newly created private file.
+- Recovery-code consumption alone is not a complete recovery path. The
+  restricted grant must survive an interrupted authenticator prompt yet be
+  consumed in the same transaction that stores the verified replacement
+  passkey and replacement code digests. `authrecovery.BeginPasskey` and
+  `FinishPasskey` now provide that boundary without creating an authenticated
+  session; Gamertan keeps the raw grant only in a short-lived HttpOnly cookie.

docs/GETTING_STARTED.md

@@ -26,7 +26,7 @@ The packages are ordinary Go imports. Pin the current preview and verify its
 module checksum:
 
 ```bash
-go get gamertan.com/web/requestmeta@v0.1.0-preview.12
+go get gamertan.com/web/requestmeta@v0.1.0-preview.13
 go mod verify
 ```
 

docs/MODULES.md

@@ -18,7 +18,7 @@ import "gamertan.com/web/requestmeta"
 and request the containing module at an exact version:
 
 ```bash
-go get gamertan.com/web/requestmeta@v0.1.0-preview.12
+go get gamertan.com/web/requestmeta@v0.1.0-preview.13
 ```
 
 Only imported packages are compiled and linked. The packages nevertheless

docs/PASSKEYS.md

@@ -56,13 +56,29 @@ JavaScript, or set sessions automatically.
 
 ## Recovery and credential lifecycle
 
-Recovery is deliberately host-local and should never be reachable through an
+Administrator-assisted `authwebauthn.Recover` is deliberately host-local and
-HTTP handler. It revokes all user sessions and pending ceremonies, replaces
+must never be reachable through an HTTP handler. It revokes all user sessions
-prior enrollment tokens, appends a secret-free audit event, and returns one
+and pending ceremonies, replaces prior enrollment tokens, appends a
-15-minute token. It does not delete existing passkeys. After enrolling a
+secret-free audit event, and returns one 15-minute token. It does not delete
-replacement, the operator reviews credential labels and removes lost keys with
+existing passkeys. After enrolling a replacement, the operator reviews
-a fresh passkey-bound removal ceremony. The final passkey cannot be removed
+credential labels and removes lost keys with a fresh passkey-bound removal
-remotely.
+ceremony. The final passkey cannot be removed remotely.
+
+An account may separately expose self-service password-plus-recovery-code
+recovery through `authrecovery`. `Begin` verifies the password, consumes one
+printable code, revokes sessions, and returns a short-lived grant—not a normal
+session. Keep that grant in a narrowly scoped, Secure, HttpOnly, SameSite cookie
+and never place it in a URL. `BeginPasskey` binds its digest into the WebAuthn
+ceremony. `FinishPasskey` atomically consumes the grant, stores the verified
+replacement passkey, replaces the entire recovery-code set, revokes any
+sessions or ceremonies created during recovery, and returns the new plaintext
+codes exactly once. It does not issue a session; return the user to normal
+login after displaying and saving the new codes.
+
+A failed storage commit leaves the restricted grant available for a fresh
+ceremony until expiry. A binding mismatch consumes the mismatched ceremony.
+Applications must use generic failure responses and the same credential-attempt
+rate limiting as login.
 
 Before enabling production mutations, applications should require at least two
 independent passkeys and complete a local recovery drill.