CLAUDE.md

@@ -123,7 +123,7 @@ Gateway gRPC clients authenticate with an API key in metadata: `authorization: B
 
 Session event streaming is **owner-scoped**: the API key that opened a session is recorded on the session, and every `StreamEvents` attach/reattach is rejected with `PermissionDenied` unless the caller's key id matches the owner. Possessing the `event` scope and knowing a session id is not sufficient — this closes the reconnect/fan-out trust boundary (detach-grace and replay retention are on by default) so an `event`-scoped key cannot attach to another key's retained session.
 
-Dashboard auth is LDAP-backed (separate from the gRPC API-key model). `/login` binds against `MxGateway:Ldap` and maps the user's LDAP groups to `Admin` or `Viewer` via `MxGateway:Dashboard:GroupToRole`, then issues an HTTP-only secure `__Host-MxGatewayDashboard` cookie. SignalR hubs at `/hubs/{snapshot,alarms,events}` accept either the cookie or a 5-minute bearer minted at `/hubs/token`. `Dashboard:AllowAnonymousLocalhost` (default `true`) grants **read-only** loopback access — it satisfies the Viewer requirement but never the Admin-only requirement, so anonymous localhost can view the dashboard but not reach API-key CRUD or session Close/Kill (`Authentication:Mode=Disabled` is scoped the same way). `Dashboard:DisableLogin` (default `false`) auto-authenticates every dashboard request — including remote browsers — as `Dashboard:AutoLoginUser` (default `multi-role`) with both Admin and Viewer roles; dev/test only, never enable in production.
+Dashboard auth is LDAP-backed (separate from the gRPC API-key model). `/login` binds against `MxGateway:Ldap` and maps the user's LDAP groups to `Admin` or `Viewer` via `MxGateway:Dashboard:GroupToRole`, then issues an HTTP-only secure cookie named `__Host-MxGatewayDashboard` when `Dashboard:RequireHttpsCookie` is true (default) and no `Dashboard:CookieName` override is set, else the plain `MxGatewayDashboard` (the `__Host-` prefix requires a Secure cookie). SignalR hubs at `/hubs/{snapshot,alarms,events}` accept either the cookie or a 5-minute bearer minted at `/hubs/token`. `Dashboard:AllowAnonymousLocalhost` (default `true`) grants **read-only** loopback access — it satisfies the Viewer requirement but never the Admin-only requirement, so anonymous localhost can view the dashboard but not reach API-key CRUD or session Close/Kill (`Authentication:Mode=Disabled` is scoped the same way). `Dashboard:DisableLogin` (default `false`) auto-authenticates every dashboard request — including remote browsers — as `Dashboard:AutoLoginUser` (default `multi-role`) with both Admin and Viewer roles; dev/test only, never enable in production.
 
 ## Process / Platform Notes
 

docs/GatewayConfiguration.md

@@ -178,7 +178,7 @@ events (a "gap") and must re-snapshot; whatever is still retained is replayed.
 | `MxGateway:Dashboard:Enabled` | `true` | Enables Blazor Server dashboard route mapping. The dashboard mounts at the host root (`/`); there is no separate path-base prefix. |
 | `MxGateway:Dashboard:AllowAnonymousLocalhost` | `true` | Allows loopback dashboard requests to bypass the dashboard cookie requirement for local development. Remote requests still require dashboard authentication. |
 | `MxGateway:Dashboard:RequireHttpsCookie` | `true` | Sets the dashboard auth cookie's secure policy. `true` keeps `CookieSecurePolicy.Always` — the cookie is only sent over HTTPS, which matches a production HTTPS deployment. Set to `false` for plain-HTTP dev deployments to use `CookieSecurePolicy.SameAsRequest`; the cookie is still flagged Secure on HTTPS requests, but it can round-trip over HTTP. Browsers drop Secure cookies set over HTTP from non-localhost hosts, so leaving this `true` while serving the dashboard over plain HTTP will break login from any remote browser. |
-| `MxGateway:Dashboard:CookieName` | `MxGatewayDashboard` | Dashboard auth cookie name. Leave unset (null/blank) to use the default. Override it to give a distinct name to a gateway that shares a hostname with another gateway instance: browser cookies are scoped by host+path but **not** by port, so two instances on the same host would otherwise clobber each other's dashboard session under a shared cookie name. Changing it signs out existing dashboard sessions on next deploy. |
+| `MxGateway:Dashboard:CookieName` | _(unset)_ | Dashboard auth cookie name. Leave unset (null/blank) to use the resolved default: `__Host-MxGatewayDashboard` when `RequireHttpsCookie` is `true` (Secure cookie, so the `__Host-` prefix's Secure/no-Domain/`Path=/` guarantees apply), else the plain `MxGatewayDashboard` (a `__Host-` cookie without Secure is silently dropped by browsers). Override it to give a distinct name to a gateway that shares a hostname with another gateway instance: browser cookies are scoped by host+path but **not** by port, so two instances on the same host would otherwise clobber each other's dashboard session under a shared cookie name. An explicit override always wins over the `__Host-` default. Changing it signs out existing dashboard sessions on next deploy. |
 | `MxGateway:Dashboard:SnapshotIntervalMilliseconds` | `1000` | Dashboard snapshot refresh interval used by the snapshot SignalR hub and the pages that subscribe to it. |
 | `MxGateway:Dashboard:RecentFaultLimit` | `100` | Maximum number of fault summaries projected into each dashboard snapshot. |
 | `MxGateway:Dashboard:RecentSessionLimit` | `200` | Maximum number of session summaries projected into each dashboard snapshot. |

docs/GatewayDashboardDesign.md

@@ -435,7 +435,11 @@ Implemented behavior:
   `ClaimTypes.Role` claims, alongside the per-group `mxgateway:ldap_group`
   claims;
 - a successful login signs in the `MxGateway.Dashboard` cookie scheme
-  (`__Host-MxGatewayDashboard`, HttpOnly, SameSite=Strict, Secure);
+  (HttpOnly, SameSite=Strict, Secure); the cookie is named
+  `__Host-MxGatewayDashboard` when `MxGateway:Dashboard:RequireHttpsCookie` is
+  true (default) and no `MxGateway:Dashboard:CookieName` override is set,
+  otherwise the plain `MxGatewayDashboard` name is used (the `__Host-` prefix is
+  only honoured on a Secure cookie);
 - a user with no matching group cannot sign in — the login screen returns the
   generic credential-rejected message;
 - antiforgery tokens guard the login and logout POSTs.

docs/GatewayProcessDesign.md

@@ -699,8 +699,11 @@ password in a form post, calls `DashboardAuthenticator` to bind against
 `MxGateway:Ldap`, resolves the user's LDAP groups through
 `MxGateway:Dashboard:GroupToRole` to one of `Admin` / `Viewer`, and signs in
 with the `MxGateway.Dashboard` cookie scheme. The cookie is HTTP-only,
-secure, strict SameSite, and named `__Host-MxGatewayDashboard`. Logout
+secure, and strict SameSite. It is named `__Host-MxGatewayDashboard` when
-clears it. Login and logout posts validate antiforgery tokens. SignalR
+`MxGateway:Dashboard:RequireHttpsCookie` is true (default) and no
+`MxGateway:Dashboard:CookieName` override is set; otherwise it falls back to the
+plain `MxGatewayDashboard` name (the `__Host-` prefix requires a Secure cookie).
+Logout clears it. Login and logout posts validate antiforgery tokens. SignalR
 connections additionally accept a 30-minute data-protected bearer minted at
 `/hubs/token`. `Dashboard:AllowAnonymousLocalhost` permits loopback requests
 to bypass the cookie requirement and defaults to `true`.

docs/ImplementationPlanGateway.md

@@ -451,7 +451,9 @@ Deliverables:
 - LDAP bind against `MxGateway:Ldap`,
 - LDAP-group → role mapping (`Admin` / `Viewer`) via
   `MxGateway:Dashboard:GroupToRole`,
-- HTTP-only secure cookie (`__Host-MxGatewayDashboard`),
+- HTTP-only secure cookie (`__Host-MxGatewayDashboard` when
+  `RequireHttpsCookie` is true and no `CookieName` override; else
+  `MxGatewayDashboard`),
 - `/hubs/token` bearer mint for SignalR connections,
 - `/logout`,
 - antiforgery protection,

gateway.md

@@ -219,7 +219,12 @@ Dashboard authentication is LDAP-backed (distinct from the API-key model on
 the gRPC API). `/login` accepts username and password in a form body, binds
 against `MxGateway:Ldap`, maps the user's LDAP groups to `Admin` or `Viewer`
 via `MxGateway:Dashboard:GroupToRole`, and issues an HTTP-only secure
-`__Host-MxGatewayDashboard` cookie. `/logout` clears it. Login and logout
+cookie. The cookie is named `__Host-MxGatewayDashboard` when
+`MxGateway:Dashboard:RequireHttpsCookie` is true (the default, forcing Secure)
+and no `MxGateway:Dashboard:CookieName` override is set; otherwise it is named
+`MxGatewayDashboard` (the `__Host-` prefix is only valid on a Secure cookie, so
+it is dropped for HTTP-dev or custom-name deployments). `/logout` clears it.
+Login and logout
 posts validate antiforgery tokens. SignalR hub connections accept either the
 cookie or a 30-minute data-protected bearer minted at `/hubs/token`.
 `MxGateway:Dashboard:AllowAnonymousLocalhost` permits loopback to bypass the

src/ZB.MOM.WW.MxGateway.Server/Dashboard/DashboardAuthenticationDefaults.cs

@@ -35,5 +35,23 @@ public static class DashboardAuthenticationDefaults
 
     public const string LdapGroupClaimType = "mxgateway:ldap_group";
     public const string KeyPrefixClaimType = "mxgateway:key_prefix";
+
+    /// <summary>
+    /// Dashboard auth cookie name used when the cookie is not guaranteed to be Secure
+    /// (<c>RequireHttpsCookie=false</c> → <see cref="Microsoft.AspNetCore.Authentication.Cookies.CookieSecurePolicy.SameAsRequest"/>)
+    /// or when an explicit <c>MxGateway:Dashboard:CookieName</c> override is absent but the
+    /// secure default cannot be applied. This plain name carries no browser-enforced guarantees.
+    /// </summary>
     public const string CookieName = "MxGatewayDashboard";
+
+    /// <summary>
+    /// Dashboard auth cookie name applied when the cookie is guaranteed Secure
+    /// (<c>RequireHttpsCookie=true</c> → <see cref="Microsoft.AspNetCore.Authentication.Cookies.CookieSecurePolicy.Always"/>)
+    /// and no explicit <c>MxGateway:Dashboard:CookieName</c> override is set. The <c>__Host-</c>
+    /// prefix instructs browsers to enforce Secure, no <c>Domain</c>, and <c>Path=/</c>; those
+    /// guarantees only hold for a Secure cookie, so this name must never be applied unless
+    /// <see cref="Microsoft.AspNetCore.Authentication.Cookies.CookieSecurePolicy.Always"/> is in
+    /// effect — a <c>__Host-</c> cookie without Secure is silently dropped by browsers.
+    /// </summary>
+    public const string SecureCookieName = "__Host-MxGatewayDashboard";
 }

src/ZB.MOM.WW.MxGateway.Server/Dashboard/DashboardServiceCollectionExtensions.cs

@@ -123,13 +123,22 @@ public static class DashboardServiceCollectionExtensions
                     ? CookieSecurePolicy.Always
                     : CookieSecurePolicy.SameAsRequest;
 
-                // Config-driven cookie name (MxGateway:Dashboard:CookieName). Null/blank keeps
+                // Config-driven cookie name (MxGateway:Dashboard:CookieName). An explicit override
-                // the canonical default set above, so a misconfiguration cannot unname the cookie.
+                // always wins. With no override, restore the __Host- prefix when the cookie is
+                // guaranteed Secure (RequireHttpsCookie true → SecurePolicy Always): the __Host-
+                // browser guarantees (Secure required, no Domain, Path=/) hold only for a Secure
+                // cookie, and a __Host- cookie without Secure is silently dropped — so the prefix
+                // is never applied unless SecurePolicy is Always. Otherwise keep the plain
+                // canonical default set by AddCookie above, so a misconfiguration cannot unname it.
                 var cookieName = gatewayOptions.Value.Dashboard.CookieName;
                 if (!string.IsNullOrWhiteSpace(cookieName))
                 {
                     cookieOptions.Cookie.Name = cookieName;
                 }
+                else if (cookieOptions.Cookie.SecurePolicy == CookieSecurePolicy.Always)
+                {
+                    cookieOptions.Cookie.Name = DashboardAuthenticationDefaults.SecureCookieName;
+                }
             });
 
         services.AddAuthorization(authorization =>

src/ZB.MOM.WW.MxGateway.Tests/Gateway/Dashboard/DashboardCookieOptionsTests.cs

@@ -10,7 +10,12 @@ namespace ZB.MOM.WW.MxGateway.Tests.Gateway.Dashboard;
 
 public sealed class DashboardCookieOptionsTests
 {
-    /// <summary>Verifies that the application configures secure dashboard authentication cookies.</summary>
+    /// <summary>
+    /// Verifies that the application configures secure dashboard authentication cookies.
+    /// With <c>RequireHttpsCookie</c> defaulting to <see langword="true"/> and no explicit
+    /// <c>CookieName</c> override, the cookie is named with the <c>__Host-</c> prefix so
+    /// browsers enforce the Secure/no-Domain/Path=/ guarantees the prefix promises.
+    /// </summary>
     /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Build_ConfiguresSecureDashboardCookie()
@@ -22,7 +27,7 @@ public sealed class DashboardCookieOptionsTests
         CookieAuthenticationOptions options = optionsMonitor.Get(
             DashboardAuthenticationDefaults.AuthenticationScheme);
 
-        Assert.Equal(DashboardAuthenticationDefaults.CookieName, options.Cookie.Name);
+        Assert.Equal(DashboardAuthenticationDefaults.SecureCookieName, options.Cookie.Name);
         Assert.True(options.Cookie.HttpOnly);
         Assert.Equal(CookieSecurePolicy.Always, options.Cookie.SecurePolicy);
         Assert.Equal(SameSiteMode.Strict, options.Cookie.SameSite);
@@ -35,11 +40,14 @@ public sealed class DashboardCookieOptionsTests
     /// <summary>
     /// Verifies that setting <c>MxGateway:Dashboard:RequireHttpsCookie=false</c>
     /// relaxes the cookie to <see cref="CookieSecurePolicy.SameAsRequest"/> so
-    /// the dashboard can be reached over plain HTTP in dev.
+    /// the dashboard can be reached over plain HTTP in dev, and that the plain
+    /// <see cref="DashboardAuthenticationDefaults.CookieName"/> is used rather than the
+    /// <c>__Host-</c> name — a <c>__Host-</c> cookie without a guaranteed Secure flag is
+    /// silently dropped by browsers.
     /// </summary>
     /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
-    public async Task Build_WithRequireHttpsCookieFalse_UsesSameAsRequest()
+    public async Task Build_WithRequireHttpsCookieFalse_UsesSameAsRequestAndPlainName()
     {
         await using WebApplication app = GatewayApplication.Build(
             ["--MxGateway:Dashboard:RequireHttpsCookie=false"]);
@@ -50,12 +58,14 @@ public sealed class DashboardCookieOptionsTests
             DashboardAuthenticationDefaults.AuthenticationScheme);
 
         Assert.Equal(CookieSecurePolicy.SameAsRequest, options.Cookie.SecurePolicy);
+        Assert.Equal(DashboardAuthenticationDefaults.CookieName, options.Cookie.Name);
     }
 
     /// <summary>
-    /// Verifies that <c>MxGateway:Dashboard:CookieName</c> overrides the dashboard auth
+    /// Verifies that an explicit <c>MxGateway:Dashboard:CookieName</c> override wins over the
-    /// cookie name, so a gateway instance sharing a hostname with another can be given a
+    /// secure <c>__Host-</c> default (this build leaves <c>RequireHttpsCookie</c> at its
-    /// distinct name (browser cookies are scoped by host+path, not port).
+    /// <see langword="true"/> default), so a gateway instance sharing a hostname with another
+    /// can be given a distinct name (browser cookies are scoped by host+path, not port).
     /// </summary>
     /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]