diff --git a/code-reviews/Security/findings.md b/code-reviews/Security/findings.md
index 69ce213..f91b950 100644
--- a/code-reviews/Security/findings.md
+++ b/code-reviews/Security/findings.md
@@ -8,7 +8,7 @@
 | Last reviewed | 2026-05-17 |
 | Reviewer | claude-agent |
 | Commit reviewed | `39d737e` |
-| Open findings | 4 (1 deferred — Security-008) |
+| Open findings | 0 (1 deferred — Security-008) |
 
 ## Summary
 
@@ -483,7 +483,7 @@ LDAP-timeout coverage (Security-009) plus extra no-service-account / DN-path edg
 |--|--|
 | Severity | Medium |
 | Category | Error handling & resilience |
-| Status | Open |
+| Status | Resolved |
 | Location | `src/ScadaLink.Security/LdapAuthService.cs:78-118` |
 
 **Description**
@@ -515,7 +515,19 @@ or be surfaced.
 
 **Resolution**
 
-_Unresolved._
+Resolved 2026-05-17 (commit `pending`). Confirmed: the group/attribute `Search` was
+wrapped in a `catch (LdapException)` that logged a warning and returned
+`new LdapAuthResult(true, …, groups: [])` — a partial LDAP outage produced an
+authenticated, zero-role session — and the inner `while`-loop `catch { break; }` masked
+real mid-enumeration errors as end-of-results. `AuthenticateAsync` now tracks a
+`groupLookupSucceeded` flag (false when any `LdapException` is thrown by the search or
+`Next()`); the inner swallowing catch was removed so such errors propagate; the new
+`BuildAuthResultFromGroupLookup` helper returns a FAILED `LdapAuthResult`
+("directory temporarily unavailable, please try again") on lookup failure while still
+treating a genuine empty-groups result as a successful login. Regression tests
+`BuildAuthResultFromGroupLookup_LookupFailed_FailsTheLogin`,
+`BuildAuthResultFromGroupLookup_LookupSucceededNoGroups_IsAuthenticated`,
+`BuildAuthResultFromGroupLookup_LookupSucceededWithGroups_CarriesGroups`.
 
 ### Security-013 — `ExtractFirstRdnValue` mis-parses group DNs containing escaped commas
 
@@ -523,7 +535,7 @@ _Unresolved._
 |--|--|
 | Severity | Low |
 | Category | Correctness & logic bugs |
-| Status | Open |
+| Status | Resolved |
 | Location | `src/ScadaLink.Security/LdapAuthService.cs:258-269` |
 
 **Description**
@@ -545,7 +557,17 @@ library's DN-parsing API (`LdapDN` / RDN accessors) rather than hand-rolled `Ind
 
 **Resolution**
 
-_Unresolved._
+Resolved 2026-05-17 (commit `pending`). Confirmed: `ExtractFirstRdnValue` took the
+substring between the first `=` and the first `,`, splitting on an RFC 4514
+backslash-escaped comma so a CN like `Acme\, Inc Operators` became `Acme\`. Replaced the
+naive `IndexOf` scan with an escape-aware character scan that ignores a backslash-escaped
+`,`, unescapes single-character and `\XX` hex escape sequences, and only terminates the
+value on an unescaped comma — so a comma-containing group CN is returned intact and
+matches its configured `LdapGroupName`. Method was also made `public` for direct
+testing. Regression tests `ExtractFirstRdnValue_EscapedComma_KeepsWholeGroupName`,
+`ExtractFirstRdnValue_PlainDn_ReturnsFirstRdnValue`,
+`ExtractFirstRdnValue_SingleRdn_ReturnsValue`,
+`ExtractFirstRdnValue_EscapedSpecials_AreUnescaped`.
 
 ### Security-014 — `RefreshToken` re-issues a token without checking the idle timeout
 
@@ -553,7 +575,7 @@ _Unresolved._
 |--|--|
 | Severity | Medium |
 | Category | Security |
-| Status | Open |
+| Status | Resolved |
 | Location | `src/ScadaLink.Security/JwtTokenService.cs:156-169` |
 
 **Description**
@@ -580,7 +602,16 @@ regression test covering refresh of a 31-minute-idle token.
 
 **Resolution**
 
-_Unresolved._
+Resolved 2026-05-17 (commit `pending`). Confirmed: `RefreshToken` carried `LastActivity`
+forward and minted a fresh 15-minute token without ever calling `IsIdleTimedOut`, so the
+idle policy depended entirely on caller discipline and a background refresh could keep an
+idle-expired session alive indefinitely. `RefreshToken` now calls
+`IsIdleTimedOut(currentPrincipal)` after the missing-claims check and returns `null`
+(its existing "cannot refresh" signal) when the session is past the idle window, so the
+30-minute idle policy holds regardless of caller order; XML doc updated to state the
+invariant. Regression tests `RefreshToken_IdleExpiredPrincipal_ReturnsNull`,
+`RefreshToken_ActiveSessionWithinIdleWindow_StillRefreshes`,
+`RefreshToken_MissingLastActivityClaim_ReturnsNull`.
 
 ### Security-015 — Username is not trimmed before use in the LDAP filter, fallback DN, and JWT claims
 
@@ -588,7 +619,7 @@ _Unresolved._
 |--|--|
 | Severity | Low |
 | Category | Correctness & logic bugs |
-| Status | Open |
+| Status | Resolved |
 | Location | `src/ScadaLink.Security/LdapAuthService.cs:20-21`, `:80`, `:122`, `:169`, `:193` |
 
 **Description**
@@ -613,4 +644,13 @@ trail.
 
 **Resolution**
 
-_Unresolved._
+Resolved 2026-05-17 (commit `pending`). Confirmed: an otherwise-valid username with
+leading/trailing whitespace passed the `IsNullOrWhiteSpace` guard and flowed verbatim
+into the LDAP filter, the fallback DN, and the returned `LdapAuthResult` (and thus the
+JWT `Username` claim). Added a `NormalizeUsername` helper (trims whitespace) called once
+at the top of `AuthenticateAsync` immediately after the guard; the local `username`
+variable is reassigned to the trimmed value so the filter, fallback DN, and result all
+use the single canonical identity. Regression tests
+`NormalizeUsername_TrimsLeadingAndTrailingWhitespace`,
+`BuildFallbackUserDn_TrimmedUsername_NoLeadingTrailingSpace`,
+`AuthenticateAsync_UsernameWithSurroundingWhitespace_StillRejectedForInsecure`.
diff --git a/src/ScadaLink.Security/JwtTokenService.cs b/src/ScadaLink.Security/JwtTokenService.cs
index 17ea864..b0cd4aa 100644
--- a/src/ScadaLink.Security/JwtTokenService.cs
+++ b/src/ScadaLink.Security/JwtTokenService.cs
@@ -152,6 +152,14 @@ public class JwtTokenService
     /// otherwise the documented 30-minute idle timeout could never fire for a client
     /// that polls in the background. Call <see cref="RecordActivity"/> to advance the
     /// anchor when handling a genuine user request.
+    /// <para>
+    /// A principal that is already past the idle timeout cannot be refreshed: this
+    /// method returns <c>null</c> (the same "cannot refresh" signal it uses for missing
+    /// claims). Enforcing the idle check here — rather than relying on the caller to
+    /// invoke <see cref="IsIdleTimedOut"/> first — guarantees the documented 30-minute
+    /// idle policy holds regardless of caller discipline; otherwise an idle-expired
+    /// session could be kept alive indefinitely by background refreshes (Security-014).
+    /// </para>
     /// </summary>
     public string? RefreshToken(ClaimsPrincipal currentPrincipal, IReadOnlyList<string> currentRoles, IReadOnlyList<string>? permittedSiteIds)
     {
@@ -164,6 +172,14 @@ public class JwtTokenService
             return null;
         }
 
+        // An idle-expired session must not be renewed — the user must re-login.
+        if (IsIdleTimedOut(currentPrincipal))
+        {
+            _logger.LogInformation(
+                "Cannot refresh token for {Username}: session is past the idle timeout", username);
+            return null;
+        }
+
         return GenerateToken(displayName, username, currentRoles, permittedSiteIds,
             ReadLastActivity(currentPrincipal));
     }
diff --git a/src/ScadaLink.Security/LdapAuthService.cs b/src/ScadaLink.Security/LdapAuthService.cs
index 9ad6ecc..1b8b161 100644
--- a/src/ScadaLink.Security/LdapAuthService.cs
+++ b/src/ScadaLink.Security/LdapAuthService.cs
@@ -23,6 +23,14 @@ public class LdapAuthService
         if (string.IsNullOrWhiteSpace(password))
             return new LdapAuthResult(false, null, null, null, "Password is required.");
 
+        // Trim once, up front: a username with leading/trailing whitespace (copy-paste
+        // artefacts, mobile keyboards) is otherwise passed verbatim into the LDAP filter,
+        // the fallback bind DN, and — most consequentially — the JWT Username claim and
+        // audit trail, producing two distinct identities for the same person
+        // (Security-015). The IsNullOrWhiteSpace guard above already rejects an
+        // all-whitespace value, so the trimmed result here is always non-empty.
+        username = NormalizeUsername(username);
+
         // Enforce TLS unless explicitly allowed for dev/test
         if (_options.LdapTransport == LdapTransport.None && !_options.AllowInsecureLdap)
         {
@@ -74,6 +82,7 @@ public class LdapAuthService
             // Query for user attributes and group memberships
             var displayName = username;
             var groups = new List<string>();
+            var groupLookupSucceeded = true;
 
             try
             {
@@ -86,40 +95,45 @@ public class LdapAuthService
                         new[] { _options.LdapDisplayNameAttribute, _options.LdapGroupAttribute },
                         false), ct);
 
+                // `HasMore()` is the loop guard for end-of-results; it returns false
+                // when the enumeration is exhausted. An LdapException thrown by
+                // `Next()` inside a HasMore()-guarded loop is therefore NOT a benign
+                // "no more results" sentinel — it is a genuine error (referral failure,
+                // server-side limit, transport drop mid-enumeration). The previous
+                // `catch (LdapException) { break; }` silently truncated the group list
+                // and masked a partial outage (Security-012); such an exception now
+                // propagates to the outer catch and fails the login.
                 while (searchResults.HasMore())
                 {
-                    try
-                    {
-                        var entry = searchResults.Next();
-                        var dnAttr = entry.GetAttribute(_options.LdapDisplayNameAttribute);
-                        if (dnAttr != null)
-                            displayName = dnAttr.StringValue;
+                    var entry = searchResults.Next();
 
-                        var groupAttr = entry.GetAttribute(_options.LdapGroupAttribute);
-                        if (groupAttr != null)
-                        {
-                            foreach (var groupDn in groupAttr.StringValueArray)
-                            {
-                                groups.Add(ExtractFirstRdnValue(groupDn));
-                            }
-                        }
-                    }
-                    catch (LdapException)
+                    var dnAttr = entry.GetAttribute(_options.LdapDisplayNameAttribute);
+                    if (dnAttr != null)
+                        displayName = dnAttr.StringValue;
+
+                    var groupAttr = entry.GetAttribute(_options.LdapGroupAttribute);
+                    if (groupAttr != null)
                     {
-                        // No more results
-                        break;
+                        foreach (var groupDn in groupAttr.StringValueArray)
+                        {
+                            groups.Add(ExtractFirstRdnValue(groupDn));
+                        }
                     }
                 }
             }
             catch (LdapException ex)
             {
-                _logger.LogWarning(ex, "Failed to query LDAP attributes for user {Username}; authentication succeeded but group lookup failed", username);
-                // Auth succeeded even if attribute lookup failed
+                // A failed group/attribute lookup on initial login means the directory
+                // is partially unavailable. The design's LDAP-failure rule requires new
+                // logins to FAIL when LDAP is unavailable — admitting the user here
+                // would yield an authenticated session with zero roles (Security-012).
+                _logger.LogWarning(ex, "LDAP group/attribute lookup failed for user {Username}; failing the login per the LDAP-failure rule", username);
+                groupLookupSucceeded = false;
             }
 
             connection.Disconnect();
 
-            return new LdapAuthResult(true, displayName, username, groups, null);
+            return BuildAuthResultFromGroupLookup(username, displayName, groups, groupLookupSucceeded);
         }
         catch (LdapException ex)
         {
@@ -255,16 +269,92 @@ public class LdapAuthService
             .Replace("\0", "\\00");
     }
 
-    private static string ExtractFirstRdnValue(string dn)
+    /// <summary>
+    /// Normalises a username by trimming leading and trailing whitespace. Applied once
+    /// at the top of <see cref="AuthenticateAsync"/> so the same canonical value flows
+    /// into the LDAP filter, the fallback bind DN, and the JWT <c>Username</c> claim —
+    /// avoiding two distinct identities for the same person (Security-015).
+    /// </summary>
+    public static string NormalizeUsername(string username)
+        => username?.Trim() ?? string.Empty;
+
+    /// <summary>
+    /// Builds the final <see cref="LdapAuthResult"/> for a login attempt once the user
+    /// bind has succeeded. When the group/attribute lookup failed
+    /// (<paramref name="groupLookupSucceeded"/> is false) the directory is partially
+    /// unavailable, so the login is FAILED per the design's LDAP-failure rule rather
+    /// than returning an authenticated session with zero roles (Security-012). When the
+    /// lookup succeeded, an empty <paramref name="groups"/> list is a genuine
+    /// "no mapped groups" outcome and the login succeeds.
+    /// </summary>
+    public static LdapAuthResult BuildAuthResultFromGroupLookup(
+        string username,
+        string displayName,
+        IReadOnlyList<string> groups,
+        bool groupLookupSucceeded)
     {
-        // Extract the value of the first RDN from a DN.
-        // Handles cn=, ou=, or any attribute: "ou=SCADA-Admins,ou=groups,dc=..." → "SCADA-Admins"
+        if (!groupLookupSucceeded)
+        {
+            return new LdapAuthResult(false, null, username, null,
+                "The directory is temporarily unavailable. Please try again.");
+        }
+
+        return new LdapAuthResult(true, displayName, username, groups, null);
+    }
+
+    /// <summary>
+    /// Extracts the value of the first RDN from a DN, e.g.
+    /// <c>ou=SCADA-Admins,ou=groups,dc=...</c> → <c>SCADA-Admins</c>. The scan is
+    /// RFC 4514 escape-aware: a backslash-escaped <c>,</c> inside the RDN value does
+    /// not terminate it, and recognised escape sequences are unescaped, so a group CN
+    /// that legitimately contains a comma is returned intact (Security-013).
+    /// </summary>
+    public static string ExtractFirstRdnValue(string dn)
+    {
+        if (string.IsNullOrEmpty(dn))
+            return dn;
+
         var equalsIndex = dn.IndexOf('=');
         if (equalsIndex < 0)
             return dn;
 
         var valueStart = equalsIndex + 1;
-        var commaIndex = dn.IndexOf(',', valueStart);
-        return commaIndex > valueStart ? dn[valueStart..commaIndex] : dn[valueStart..];
+        var sb = new System.Text.StringBuilder(dn.Length - valueStart);
+
+        for (var i = valueStart; i < dn.Length; i++)
+        {
+            var c = dn[i];
+            if (c == '\\' && i + 1 < dn.Length)
+            {
+                var next = dn[i + 1];
+                // RFC 4514 hex escape: \XX (two hex digits).
+                if (i + 2 < dn.Length && IsHexDigit(next) && IsHexDigit(dn[i + 2]))
+                {
+                    sb.Append((char)Convert.ToInt32(dn.Substring(i + 1, 2), 16));
+                    i += 2;
+                }
+                else
+                {
+                    // Single-character escape (e.g. \, \+ \\ \" \; etc.) — emit the
+                    // escaped character literally and skip the backslash.
+                    sb.Append(next);
+                    i += 1;
+                }
+                continue;
+            }
+
+            if (c == ',')
+            {
+                // Unescaped comma terminates the first RDN.
+                break;
+            }
+
+            sb.Append(c);
+        }
+
+        return sb.ToString();
     }
+
+    private static bool IsHexDigit(char c)
+        => (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F');
 }
diff --git a/tests/ScadaLink.Security.Tests/SecurityTests.cs b/tests/ScadaLink.Security.Tests/SecurityTests.cs
index 9632719..4abc7af 100644
--- a/tests/ScadaLink.Security.Tests/SecurityTests.cs
+++ b/tests/ScadaLink.Security.Tests/SecurityTests.cs
@@ -804,6 +804,236 @@ public class SecurityReviewRegressionTests3
 
 #endregion
 
+#region Code Review Regression Tests — Security-012/013/014/015
+
+/// <summary>
+/// Regression tests for Security-012 (a partial LDAP outage during login — bind OK but
+/// group search failing — silently yields a roleless authenticated session),
+/// Security-013 (<c>ExtractFirstRdnValue</c> mis-parses group DNs containing an escaped
+/// comma), Security-014 (<c>RefreshToken</c> re-issues a token without checking the idle
+/// timeout, so an idle-expired session can be renewed indefinitely), and Security-015
+/// (a username with leading/trailing whitespace is not trimmed before use).
+/// </summary>
+public class SecurityReviewRegressionTests4
+{
+    private static SecurityOptions JwtOptions() => new()
+    {
+        JwtSigningKey = "this-is-a-test-signing-key-for-hmac-sha256-must-be-long-enough",
+        JwtExpiryMinutes = 15,
+        IdleTimeoutMinutes = 30,
+        JwtRefreshThresholdMinutes = 5
+    };
+
+    private static JwtTokenService CreateJwtService(SecurityOptions? options = null) =>
+        new(Options.Create(options ?? JwtOptions()), NullLogger<JwtTokenService>.Instance);
+
+    // --- Security-014: RefreshToken must reject an idle-expired principal ---
+
+    [Fact]
+    public void RefreshToken_IdleExpiredPrincipal_ReturnsNull()
+    {
+        // A user idle for 31 minutes (past the 30-minute idle window). Even though the
+        // DisplayName/Username claims are present, the refresh must be refused so an
+        // idle-expired session cannot be renewed by a background request.
+        var service = CreateJwtService();
+        var idleActivity = DateTimeOffset.UtcNow.AddMinutes(-31);
+        var principal = new ClaimsPrincipal(new ClaimsIdentity(new[]
+        {
+            new Claim(JwtTokenService.DisplayNameClaimType, "User"),
+            new Claim(JwtTokenService.UsernameClaimType, "user"),
+            new Claim(JwtTokenService.LastActivityClaimType, idleActivity.ToString("o"))
+        }, "test"));
+
+        var refreshed = service.RefreshToken(principal, new[] { "Admin" }, null);
+
+        Assert.Null(refreshed);
+    }
+
+    [Fact]
+    public void RefreshToken_ActiveSessionWithinIdleWindow_StillRefreshes()
+    {
+        // A user idle for 10 minutes (well inside the 30-minute window): refresh must
+        // still succeed — the idle-timeout guard must not break the normal sliding path.
+        var service = CreateJwtService();
+        var recentActivity = DateTimeOffset.UtcNow.AddMinutes(-10);
+        var principal = new ClaimsPrincipal(new ClaimsIdentity(new[]
+        {
+            new Claim(JwtTokenService.DisplayNameClaimType, "User"),
+            new Claim(JwtTokenService.UsernameClaimType, "user"),
+            new Claim(JwtTokenService.LastActivityClaimType, recentActivity.ToString("o"))
+        }, "test"));
+
+        var refreshed = service.RefreshToken(principal, new[] { "Admin" }, null);
+
+        Assert.NotNull(refreshed);
+    }
+
+    [Fact]
+    public void RefreshToken_MissingLastActivityClaim_ReturnsNull()
+    {
+        // No LastActivity claim — IsIdleTimedOut treats this as timed out, so the
+        // refresh must be refused rather than minting a fresh session out of nothing.
+        var service = CreateJwtService();
+        var principal = new ClaimsPrincipal(new ClaimsIdentity(new[]
+        {
+            new Claim(JwtTokenService.DisplayNameClaimType, "User"),
+            new Claim(JwtTokenService.UsernameClaimType, "user")
+        }, "test"));
+
+        var refreshed = service.RefreshToken(principal, new[] { "Admin" }, null);
+
+        Assert.Null(refreshed);
+    }
+
+    // --- Security-013: ExtractFirstRdnValue must honour RFC 4514 escaped commas ---
+
+    [Fact]
+    public void ExtractFirstRdnValue_EscapedComma_KeepsWholeGroupName()
+    {
+        // A CN that legitimately contains a comma is RFC 4514 backslash-escaped in the
+        // memberOf DN. The extracted group name must be the full unescaped CN value,
+        // not the fragment before the escaped comma.
+        var name = LdapAuthService.ExtractFirstRdnValue(
+            @"cn=Acme\, Inc Operators,ou=groups,dc=example,dc=com");
+        Assert.Equal("Acme, Inc Operators", name);
+    }
+
+    [Fact]
+    public void ExtractFirstRdnValue_PlainDn_ReturnsFirstRdnValue()
+    {
+        var name = LdapAuthService.ExtractFirstRdnValue("ou=SCADA-Admins,ou=groups,dc=example,dc=com");
+        Assert.Equal("SCADA-Admins", name);
+    }
+
+    [Fact]
+    public void ExtractFirstRdnValue_SingleRdn_ReturnsValue()
+    {
+        var name = LdapAuthService.ExtractFirstRdnValue("cn=Operators");
+        Assert.Equal("Operators", name);
+    }
+
+    [Fact]
+    public void ExtractFirstRdnValue_EscapedSpecials_AreUnescaped()
+    {
+        // RFC 4514 escape sequences (escaped '+', '"', '\\') must be unescaped in the
+        // returned value so it matches the configured LdapGroupName verbatim.
+        var name = LdapAuthService.ExtractFirstRdnValue(
+            @"cn=A\+B\\C,ou=groups,dc=example,dc=com");
+        Assert.Equal(@"A+B\C", name);
+    }
+
+    // --- Security-015: username must be trimmed before use ---
+
+    [Fact]
+    public void BuildFallbackUserDn_TrimmedUsername_NoLeadingTrailingSpace()
+    {
+        // The whitespace-edge escaping in EscapeLdapDn only fires when whitespace is NOT
+        // trimmed. AuthenticateAsync trims first; this asserts the trimmed value yields
+        // a clean DN with no escaped edge spaces.
+        var dn = LdapAuthService.BuildFallbackUserDn("alice".Trim(), "dc=example,dc=com", "uid");
+        Assert.Equal("uid=alice,dc=example,dc=com", dn);
+    }
+
+    [Fact]
+    public async Task AuthenticateAsync_UsernameWithSurroundingWhitespace_StillRejectedForInsecure()
+    {
+        // Sanity guard: a padded but otherwise-valid username is not rejected by the
+        // IsNullOrWhiteSpace guard — it passes through to the (here, insecure-LDAP) path.
+        var options = new SecurityOptions
+        {
+            LdapServer = "ldap.example.com",
+            LdapPort = 389,
+            LdapTransport = LdapTransport.None,
+            AllowInsecureLdap = false
+        };
+        var service = new LdapAuthService(Options.Create(options), NullLogger<LdapAuthService>.Instance);
+
+        var result = await service.AuthenticateAsync("  alice  ", "password");
+
+        // Reaches the insecure-LDAP guard (not the empty-username guard) — proves the
+        // padded username is treated as a real, non-empty username.
+        Assert.False(result.Success);
+        Assert.Contains("Insecure LDAP", result.ErrorMessage);
+    }
+
+    [Fact]
+    public void NormalizeUsername_TrimsLeadingAndTrailingWhitespace()
+    {
+        Assert.Equal("alice", LdapAuthService.NormalizeUsername("  alice  "));
+        Assert.Equal("alice", LdapAuthService.NormalizeUsername("alice"));
+        Assert.Equal("alice", LdapAuthService.NormalizeUsername("\talice\n"));
+    }
+}
+
+#endregion
+
+#region Code Review Regression Tests — Security-012 (partial LDAP outage)
+
+/// <summary>
+/// Regression tests for Security-012: a partial LDAP outage during login (the user bind
+/// succeeds but the subsequent group/attribute search fails) must fail the login per the
+/// design's LDAP-failure rule, rather than returning an authenticated session with zero
+/// roles. These exercise the seam through a stubbed group-lookup so the bind itself can
+/// be treated as successful.
+/// </summary>
+public class Security012GroupLookupFailureTests
+{
+    private static SecurityOptions Options() => new()
+    {
+        LdapServer = "ldap.example.com",
+        LdapPort = 636,
+        LdapTransport = LdapTransport.Ldaps,
+        LdapSearchBase = "dc=example,dc=com"
+    };
+
+    [Fact]
+    public void BuildAuthResultFromGroupLookup_LookupFailed_FailsTheLogin()
+    {
+        // When the group lookup failed (directory partially unavailable mid-login) the
+        // result must be a FAILED login — not a success with an empty group list.
+        var result = LdapAuthService.BuildAuthResultFromGroupLookup(
+            username: "alice",
+            displayName: "Alice",
+            groups: new List<string>(),
+            groupLookupSucceeded: false);
+
+        Assert.False(result.Success);
+        Assert.Null(result.Groups);
+        Assert.False(string.IsNullOrEmpty(result.ErrorMessage));
+    }
+
+    [Fact]
+    public void BuildAuthResultFromGroupLookup_LookupSucceededNoGroups_IsAuthenticated()
+    {
+        // A genuine "user belongs to no mapped groups" outcome must remain a successful
+        // login — it must be distinguishable from a failed lookup.
+        var result = LdapAuthService.BuildAuthResultFromGroupLookup(
+            username: "alice",
+            displayName: "Alice",
+            groups: new List<string>(),
+            groupLookupSucceeded: true);
+
+        Assert.True(result.Success);
+        Assert.NotNull(result.Groups);
+        Assert.Empty(result.Groups!);
+    }
+
+    [Fact]
+    public void BuildAuthResultFromGroupLookup_LookupSucceededWithGroups_CarriesGroups()
+    {
+        var result = LdapAuthService.BuildAuthResultFromGroupLookup(
+            username: "alice",
+            displayName: "Alice",
+            groups: new List<string> { "SCADA-Admins" },
+            groupLookupSucceeded: true);
+
+        Assert.True(result.Success);
+        Assert.Equal(new[] { "SCADA-Admins" }, result.Groups);
+    }
+}
+
+#endregion
+
 #region WP-9: Authorization Policy Tests
 
 public class AuthorizationPolicyTests