diff --git a/app/Tests/Settings/PreselectedProviderTests.cs b/app/Tests/Settings/PreselectedProviderTests.cs
new file mode 100644
index 00000000..9eef82eb
--- /dev/null
+++ b/app/Tests/Settings/PreselectedProviderTests.cs
@@ -0,0 +1,217 @@
+using AIStudio.Provider;
+using AIStudio.Settings;
+
+using Microsoft.Extensions.Logging.Abstractions;
+
+namespace AIStudio.Tests.Settings;
+
+/// <summary>
+/// Checks which provider an agent is handed when nobody picked one for it.
+/// </summary>
+/// <remarks>
+/// Agents such as the content cleaner or the security audit may be given a model of their own,
+/// because a small and cheap one is enough for what they do. Almost nobody does that, so what
+/// matters in practice is what happens when they have none: the model of the assistant they sit
+/// in, the app-wide default, or nothing at all. Two bugs shipped in that fallback, and both of
+/// them lived here rather than in the components -- which is why this is where they are pinned
+/// down. The component lifecycle itself is not covered; there is no bUnit in this solution.
+///
+/// Names are written out in full throughout. This assembly has an AIStudio.Tests.Tools and an
+/// AIStudio.Tests.Provider of its own, and the app has an AIStudio.Components -- all three are
+/// what a short name finds from here, and a using alias does not help, because names from the
+/// enclosing namespaces win over it.
+/// </remarks>
+[TestFixture]
+public sealed class PreselectedProviderTests
+{
+    private const string ASSISTANT_PROVIDER_ID = "11111111-1111-1111-1111-111111111111";
+    private const string AGENT_PROVIDER_ID = "22222222-2222-2222-2222-222222222222";
+    private const string APP_DEFAULT_PROVIDER_ID = "33333333-3333-3333-3333-333333333333";
+
+    [Test]
+    public void ContentCleanerFallsBackToTheAssistantProvider()
+    {
+        var settingsManager = CreateSettingsManager();
+        AddProvider(settingsManager, ASSISTANT_PROVIDER_ID, LLMProviders.OPEN_AI);
+        AddProvider(settingsManager, AGENT_PROVIDER_ID, LLMProviders.MISTRAL);
+
+        var provider = settingsManager.GetPreselectedProvider(AIStudio.Tools.Components.AGENT_TEXT_CONTENT_CLEANER, ASSISTANT_PROVIDER_ID, true);
+
+        Assert.That(provider.Id, Is.EqualTo(ASSISTANT_PROVIDER_ID), "With nothing configured for the cleaner, it has to use the model of the assistant around it.");
+    }
+
+    [Test]
+    public void ContentCleanerFallsBackToTheAppDefault()
+    {
+        var settingsManager = CreateSettingsManager();
+        AddProvider(settingsManager, ASSISTANT_PROVIDER_ID, LLMProviders.OPEN_AI);
+        AddProvider(settingsManager, APP_DEFAULT_PROVIDER_ID, LLMProviders.MISTRAL);
+        settingsManager.ConfigurationData.App.PreselectedProvider = APP_DEFAULT_PROVIDER_ID;
+
+        var provider = settingsManager.GetPreselectedProvider(AIStudio.Tools.Components.AGENT_TEXT_CONTENT_CLEANER, null, true);
+
+        Assert.That(provider.Id, Is.EqualTo(APP_DEFAULT_PROVIDER_ID), "Without an assistant model, the app-wide default is what is left before giving up.");
+    }
+
+    [Test]
+    public void ContentCleanerPrefersItsOwnProviderOverTheAssistantOne()
+    {
+        var settingsManager = CreateSettingsManager();
+        AddProvider(settingsManager, ASSISTANT_PROVIDER_ID, LLMProviders.OPEN_AI);
+        AddProvider(settingsManager, AGENT_PROVIDER_ID, LLMProviders.MISTRAL);
+        settingsManager.ConfigurationData.TextContentCleaner.PreselectAgentOptions = true;
+        settingsManager.ConfigurationData.TextContentCleaner.PreselectedAgentProvider = AGENT_PROVIDER_ID;
+
+        var provider = settingsManager.GetPreselectedProvider(AIStudio.Tools.Components.AGENT_TEXT_CONTENT_CLEANER, ASSISTANT_PROVIDER_ID, true);
+
+        Assert.That(provider.Id, Is.EqualTo(AGENT_PROVIDER_ID), "A model picked for the cleaner is the whole point of picking one, so it outranks the assistant's.");
+    }
+
+    /// <summary>
+    /// Checks that the switch above the cleaner's provider field really turns that provider off.
+    /// </summary>
+    /// <remarks>
+    /// The provider id stays in the settings when the switch goes off, so the only thing saying it
+    /// must not be used is this one flag. A component which reads the stored id instead of asking
+    /// here would keep using a provider the user switched away from.
+    /// </remarks>
+    [Test]
+    public void ContentCleanerIgnoresItsOwnProviderWhenPreselectionIsOff()
+    {
+        var settingsManager = CreateSettingsManager();
+        AddProvider(settingsManager, ASSISTANT_PROVIDER_ID, LLMProviders.OPEN_AI);
+        AddProvider(settingsManager, AGENT_PROVIDER_ID, LLMProviders.MISTRAL);
+        settingsManager.ConfigurationData.TextContentCleaner.PreselectAgentOptions = false;
+        settingsManager.ConfigurationData.TextContentCleaner.PreselectedAgentProvider = AGENT_PROVIDER_ID;
+
+        var provider = settingsManager.GetPreselectedProvider(AIStudio.Tools.Components.AGENT_TEXT_CONTENT_CLEANER, ASSISTANT_PROVIDER_ID, true);
+
+        Assert.That(provider.Id, Is.EqualTo(ASSISTANT_PROVIDER_ID), "With its preselection switched off, the cleaner has to fall back to the assistant's model.");
+    }
+
+    /// <summary>
+    /// Checks that a model too untrusted for the cleaner is not used just because it is there.
+    /// </summary>
+    /// <remarks>
+    /// This is the case the user meets as a hint next to the cleaner switch: a model is selected in
+    /// the assistant, and the cleaner still has none. Under TRUST_ALL every provider reaches MEDIUM
+    /// and a self-hosted one reaches HIGH, so a global minimum of HIGH separates the two.
+    /// </remarks>
+    [Test]
+    public void ContentCleanerRejectsAnAssistantProviderBelowTheGlobalMinimum()
+    {
+        var settingsManager = CreateSettingsManager();
+        AddProvider(settingsManager, ASSISTANT_PROVIDER_ID, LLMProviders.OPEN_AI);
+        AddProvider(settingsManager, AGENT_PROVIDER_ID, LLMProviders.MISTRAL);
+        settingsManager.ConfigurationData.Confidence.EnforceGlobalMinimumConfidence = true;
+        settingsManager.ConfigurationData.Confidence.GlobalMinimumConfidence = ConfidenceLevel.HIGH;
+
+        var provider = settingsManager.GetPreselectedProvider(AIStudio.Tools.Components.AGENT_TEXT_CONTENT_CLEANER, ASSISTANT_PROVIDER_ID, true);
+
+        Assert.That(provider, Is.EqualTo(AIStudio.Settings.Provider.NONE), "A provider the organization ruled out must not reach the cleaner through the assistant.");
+    }
+
+    [Test]
+    public void ContentCleanerAcceptsAnAssistantProviderMeetingTheGlobalMinimum()
+    {
+        var settingsManager = CreateSettingsManager();
+        AddProvider(settingsManager, ASSISTANT_PROVIDER_ID, LLMProviders.SELF_HOSTED);
+        AddProvider(settingsManager, AGENT_PROVIDER_ID, LLMProviders.MISTRAL);
+        settingsManager.ConfigurationData.Confidence.EnforceGlobalMinimumConfidence = true;
+        settingsManager.ConfigurationData.Confidence.GlobalMinimumConfidence = ConfidenceLevel.HIGH;
+
+        var provider = settingsManager.GetPreselectedProvider(AIStudio.Tools.Components.AGENT_TEXT_CONTENT_CLEANER, ASSISTANT_PROVIDER_ID, true);
+
+        Assert.That(provider.Id, Is.EqualTo(ASSISTANT_PROVIDER_ID), "A provider which clears the bar has to be handed over, or the hint would never go away.");
+    }
+
+    /// <summary>
+    /// Checks that the audit agent's provider needs no switch to be used.
+    /// </summary>
+    /// <remarks>
+    /// Unlike the content cleaner, the audit agent has no "preselect options" flag: an organization
+    /// rolls its provider out and that is what audits run with. A test which assumed the two agents
+    /// behaved alike would pass here for the wrong reason.
+    /// </remarks>
+    [Test]
+    public void AuditAgentUsesItsOwnProviderWithoutAPreselectionSwitch()
+    {
+        var settingsManager = CreateSettingsManager();
+        AddProvider(settingsManager, AGENT_PROVIDER_ID, LLMProviders.MISTRAL);
+        AddProvider(settingsManager, APP_DEFAULT_PROVIDER_ID, LLMProviders.OPEN_AI);
+        settingsManager.ConfigurationData.App.PreselectedProvider = APP_DEFAULT_PROVIDER_ID;
+        settingsManager.ConfigurationData.AssistantPluginAudit.PreselectedAgentProvider = AGENT_PROVIDER_ID;
+
+        var provider = settingsManager.GetPreselectedProvider(AIStudio.Tools.Components.AGENT_ASSISTANT_PLUGIN_AUDIT, null, true);
+
+        Assert.That(provider.Id, Is.EqualTo(AGENT_PROVIDER_ID), "A provider rolled out for audits outranks the app-wide default.");
+    }
+
+    [Test]
+    public void AuditAgentFallsBackToTheAppDefault()
+    {
+        var settingsManager = CreateSettingsManager();
+        AddProvider(settingsManager, ASSISTANT_PROVIDER_ID, LLMProviders.OPEN_AI);
+        AddProvider(settingsManager, APP_DEFAULT_PROVIDER_ID, LLMProviders.MISTRAL);
+        settingsManager.ConfigurationData.App.PreselectedProvider = APP_DEFAULT_PROVIDER_ID;
+
+        var provider = settingsManager.GetPreselectedProvider(AIStudio.Tools.Components.AGENT_ASSISTANT_PLUGIN_AUDIT, null, true);
+
+        Assert.That(provider.Id, Is.EqualTo(APP_DEFAULT_PROVIDER_ID), "Without a dedicated audit provider, the app-wide default is what audits run with.");
+    }
+
+    /// <summary>
+    /// Checks the state the audit dialog was useless in before it offered a provider itself.
+    /// </summary>
+    [Test]
+    public void AuditAgentEndsUpWithNothingWhenNeitherIsConfigured()
+    {
+        var settingsManager = CreateSettingsManager();
+        AddProvider(settingsManager, ASSISTANT_PROVIDER_ID, LLMProviders.OPEN_AI);
+        AddProvider(settingsManager, AGENT_PROVIDER_ID, LLMProviders.MISTRAL);
+
+        var provider = settingsManager.GetPreselectedProvider(AIStudio.Tools.Components.AGENT_ASSISTANT_PLUGIN_AUDIT, null, true);
+
+        Assert.That(provider, Is.EqualTo(AIStudio.Settings.Provider.NONE), "Two configured providers are not a choice: without one being named for audits, the agent has none.");
+    }
+
+    [Test]
+    public void AuditAgentRejectsAnAppDefaultBelowTheGlobalMinimum()
+    {
+        var settingsManager = CreateSettingsManager();
+        AddProvider(settingsManager, ASSISTANT_PROVIDER_ID, LLMProviders.SELF_HOSTED);
+        AddProvider(settingsManager, APP_DEFAULT_PROVIDER_ID, LLMProviders.OPEN_AI);
+        settingsManager.ConfigurationData.App.PreselectedProvider = APP_DEFAULT_PROVIDER_ID;
+        settingsManager.ConfigurationData.Confidence.EnforceGlobalMinimumConfidence = true;
+        settingsManager.ConfigurationData.Confidence.GlobalMinimumConfidence = ConfidenceLevel.HIGH;
+
+        var provider = settingsManager.GetPreselectedProvider(AIStudio.Tools.Components.AGENT_ASSISTANT_PLUGIN_AUDIT, null, true);
+
+        Assert.That(provider, Is.EqualTo(AIStudio.Settings.Provider.NONE), "The app-wide default is not exempt from what the organization enforces.");
+    }
+
+    /// <summary>
+    /// Builds a settings manager the way these tests need it.
+    /// </summary>
+    /// <remarks>
+    /// The rust service is handed in as null on purpose: resolving a provider never asks it
+    /// anything. It reads the configured providers, the confidence scheme and the preselections,
+    /// all of which are plain settings. Should that change, the test says so by failing loudly
+    /// rather than by quietly measuring something else.
+    /// </remarks>
+    private static SettingsManager CreateSettingsManager() => new(NullLogger<SettingsManager>.Instance, null!);
+
+    /// <summary>
+    /// Adds a provider to the settings.
+    /// </summary>
+    /// <remarks>
+    /// Every test here configures at least two of them, and not for variety: with exactly one
+    /// configured provider, resolving takes a shortcut and returns it without looking at any
+    /// preselection. A single-provider test would pass no matter what the fallback does.
+    /// </remarks>
+    private static void AddProvider(SettingsManager settingsManager, string id, LLMProviders llmProvider)
+    {
+        var providers = settingsManager.ConfigurationData.Providers;
+        providers.Add(new((uint)providers.Count + 1, id, $"Instance {providers.Count + 1}", llmProvider, new("test-model", null)));
+    }
+}
\ No newline at end of file