fix: resolve the three open CodeQL alerts

CHANGELOG.md

@@ -47,6 +47,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- **Three CodeQL alerts introduced by this cycle's changes**, all in code added since 1.1.0.
+  `AtomicFile.WriteTempAsync` held its `FileStream` in a local before an `await using` block,
+  which the analyser could not prove disposed on every path (`cs/local-not-disposed`, the only
+  warning of the three) — it is now an `await using` declaration.
+  `LibsecretCredentialManager.ResolveStoredProviderName` used a filter-then-project loop where
+  LINQ says it plainly (`cs/linq/missed-select`), and a test paired `ContainsKey` with the
+  indexer instead of `TryGetValue` (`cs/inefficient-containskey`).
+
 - **The Keychain backend could see another CLI's credentials** (#55). App scoping was a
   dot-prefix match on the service string, and since the service is `{app}.{provider}` and
   provider names may contain dots, app `com.acme.cli` could not distinguish its own

src/NextIteration.SpectreConsole.Auth/Persistence/AtomicFile.cs

@@ -68,11 +68,8 @@ private static async Task WriteTempAsync(string tempPath, byte[] bytes, UnixFile
                 options.UnixCreateMode = unixMode.Value;
             }
 
-            var stream = new FileStream(tempPath, options);
-            await using (stream.ConfigureAwait(false))
-            {
-                await stream.WriteAsync(bytes, cancellationToken).ConfigureAwait(false);
-            }
+            await using var stream = new FileStream(tempPath, options);
+            await stream.WriteAsync(bytes, cancellationToken).ConfigureAwait(false);
         }
 
         /// <summary>

src/NextIteration.SpectreConsole.Auth/Persistence/Libsecret/LibsecretCredentialManager.cs

@@ -511,17 +511,12 @@ private string ResolveStoredProviderName(string providerName, CancellationToken
                 },
                 loadSecrets: false, cancellationToken);
 
-            foreach (var item in items)
-            {
-                var stored = item.Attributes.GetValueOrDefault(AttrProvider);
-                if (!string.IsNullOrEmpty(stored) &&
+            return items
+                .Select(i => i.Attributes.GetValueOrDefault(AttrProvider))
+                .FirstOrDefault(stored =>
+                    !string.IsNullOrEmpty(stored) &&
                     stored.Equals(providerName, StringComparison.OrdinalIgnoreCase))
-                {
-                    return stored;
-                }
-            }
-
-            return providerName;
+                ?? providerName;
         }
 
         /// <summary>

tests/NextIteration.SpectreConsole.Auth.Tests/Persistence/FileCredentialManagerTests.cs

@@ -314,8 +314,8 @@ public async Task DeleteCredentialAsync_ClearsSelection_IfItWasSelected()
             Assert.False(selections.ContainsKey("Adobe"));
 
             // And the delete must not disturb an unrelated provider's selection.
-            Assert.True(selections.ContainsKey("Airtable"));
-            Assert.Equal(unrelated, selections["Airtable"]);
+            Assert.True(selections.TryGetValue("Airtable", out var untouched));
+            Assert.Equal(unrelated, untouched);
 
             Assert.Null(await manager.GetSelectedCredentialAsync("Adobe"));
         }