R2 accounts are safe: email by password and code, recovery only to it, sessions that end

Completion program R2 (docs/ROADMAP.md, 2026-10-17).

- An email address is set only with the password and a 6-digit code sent to it: /clientapi/user/email, /email/verify,
  /email/remove and GET /clientapi/user/account (EmailVerification: an hour, five tries, the code's hash only;
  EmailVerificationJob through the new IMailer). The request answers one sentence whether or not the address is free,
  and nothing goes to an address another login verified. The old POST /clientapi/user/update, which changed the
  address with neither and said when one was taken, answers 422.
- Recovery writes only to a verified address; migration _019 keeps the addresses given before verification existed.
- A changed password ends every session and every persona token, and answers a new JWT for the device that changed it.
- Sessions: every JWT carries its session's id ("si", kept by sniff/again). GET /clientapi/user/logout, which did
  nothing, ends that session alone (RootUser.EndedSessions, until its tokens would expire); POST
  /clientapi/user/logout/everywhere ends them all.
- AppConfiguration:HashingOptions was never bound, so passwords were hashed at the default 9789 iterations: it is
  bound now, at 210,000, and a hash made at other iterations is made again at the next sign-in (matched on the old
  hash, so two sign-ins never undo each other).
- Recovery and verification codes expire through TTL indexes; EmailVerification is never in a backup.
- AppConfigurationService reads appsettings as they are now, not the copy older builds saved in Mongo on first boot.
- ViewUserSettings and RootUserSettings carry SavedAt, so a client signing in keeps its own theme until one saved.
- Pasture: peers/mailpit.sh (Mailpit 1.31.4 as mailpit.test) receives PrivaPub's mail; recovery links open
  https://decepub.test. scenarios/accounts.sh, in sweep batch A, checks all of the above (28 checks).

Verified: dotnet build PrivaPub.sln -c Release; the pasture with gts and mailpit: accounts 28/28 and gts, 91 passed,
0 failed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WpVCoDeM1qUTRp4fXQdfof

PrivaPub/StaticServices/AuthTokenManager.cs

@@ -14,6 +14,9 @@ namespace PrivaPub.StaticServices
 	{
 		public const string SessionStamp = "ss";
 		const string SessionStampClaim = SessionStamp;//the root's RootUser.SessionStamp when issued; JwtEvents refuses a stale one
+		// one sign-in on one device: its tokens, renewals included, carry the same id, so signing out ends that device alone
+		// (RootUser.EndedSessions). Not "sid", which JwtBearer maps to another claim type on the way in.
+		public const string SessionId = "si";
 
 		readonly IConfiguration Configuration;
 
@@ -22,9 +25,12 @@ namespace PrivaPub.StaticServices
 			Configuration = configuration;
 		}
 
-		public JwtUser GenerateToken(RootUser user, ViewUserSettings userSettings)
+		public TimeSpan Lifetime => TimeSpan.FromHours(int.Parse(Configuration["AppConfiguration:Jwt:HoursTimeout"]));
+
+		/// <summary>A token for the root; a renewal passes the session it renews, a new sign-in gets a new one.</summary>
+		public JwtUser GenerateToken(RootUser user, ViewUserSettings userSettings, string sessionId = default)
 		{
-			var expiration = DateTime.UtcNow.AddHours(int.Parse(Configuration["AppConfiguration:Jwt:HoursTimeout"]));
+			var expiration = DateTime.UtcNow + Lifetime;
 			var securityKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(Configuration["AppConfiguration:Jwt:Key"]));
 			var jwtUser = new JwtUser
 			{
@@ -39,7 +45,8 @@ namespace PrivaPub.StaticServices
 			{
 				new(ClaimTypes.UserData, user.ID),
 				new(ClaimTypes.Name, user.UserName),
-				new(SessionStampClaim, user.SessionStamp ?? string.Empty)
+				new(SessionStampClaim, user.SessionStamp ?? string.Empty),
+				new(SessionId, string.IsNullOrEmpty(sessionId) ? Guid.NewGuid().ToString("N") : sessionId)
 			};
 
 			claims.Add(new(Policies.IsUser, $"{user.Policies.Contains(Policies.IsUser)}".ToLower()));
@@ -57,4 +64,4 @@ namespace PrivaPub.StaticServices
 			return jwtUser;
 		}
 	}
-}
+}