@@ -27,3 +27,4 @@ java/.project
 java/.settings
 java/scripts/codegen/node_modules/
 .flattened-pom.xml
+/.sdk-e2e-metrics/
@@ -204,8 +204,9 @@ client.stop().get();
 | `type` | `"openai"` \| `"azure"` \| `"anthropic"` | Provider type (default: `"openai"`) |
 | `baseUrl` / `base_url` | string | **Required.** API endpoint URL |
 | `apiKey` / `api_key` | string | API key (optional for local providers like Ollama) |
+| `apiKeyCommand` / `api_key_command` | string | Command run by the runtime before each provider request to obtain a fresh API key. Also exposed as `ApiKeyCommand` in .NET and `APIKeyCommand` in Go. Credential-command failures fail the turn before sending a model request. |
 | `bearerToken` / `bearer_token` | string | Bearer token auth (takes precedence over apiKey) |
-| `bearerTokenProvider` / `bearer_token_provider` | callback | Returns a bearer token on demand (takes precedence over `apiKey` and `bearerToken`) |
+| `bearerTokenProvider` / `bearer_token_provider` | callback | Returns a bearer token on demand (takes precedence over `apiKey`, `apiKeyCommand`, and `bearerToken`; the command does not run) |
 | `wireApi` / `wire_api` | `"completions"` \| `"responses"` | Select `"completions"` for broad model compatibility (the Chat Completions API); select `"responses"` for multi-turn state management, tool namespacing, and reasoning support (the Responses API). Anthropic models always use the Messages API regardless of this setting. |
 | `azure.apiVersion` / `azure.api_version` | string | Azure API version. When set, the runtime uses the versioned deployment route; when omitted, it uses the GA versionless `v1` route. |
 
 
@@ -33,6 +33,8 @@ flowchart LR
 
 All hooks are **optional**—register only the ones you need. Returning `null` (or the language equivalent) from any hook tells the SDK to continue with default behavior.
 
+File-based repository hooks and repository hook settings are loaded only after the workspace is trusted. User hooks remain available before workspace trust is granted.
+
 ## Repository hooks from additional directories
 
 Repository filesystem hooks are separate from the SDK callbacks described in
 
@@ -254,6 +254,8 @@ const session = await client.createSession({
 
 The `onSessionEnd` hook is called when a session ends.
 
+A standalone SDK session remains active between prompts. Completing a prompt does not end the session; disconnect or dispose the session to run its end hook.
+
 ### Hook signature
 
 <details open>
 
@@ -241,7 +241,6 @@ Create a new conversation session.
 - `InfiniteSessions` - Configure automatic context compaction (see below)
 - `WorkingDirectory` - Working directory for the session. When not set, the runtime uses its own process working directory.
 - `EnableSessionStore` - Enables the cross-session store for search and retrieval across sessions. When unset in `CopilotClientMode.CopilotCli`, the runtime default applies (enabled). In `CopilotClientMode.Empty`, defaults to disabled.
-- `EnableGitHubCacheStore` - Requests the read-only GitHub cache store (`github-cache-store` capability) on create or resume. The runtime registers the `github_sql` tool only when its `GITHUB_CACHE_STORE` feature flag is also on. Defaults to disabled in every mode.
 - `GitHubTokenProvider` - Acquires session-scoped GitHub tokens on demand. Return `GitHubTokenProviderResult.FromToken` with a positive `ExpiresIn` value (production GitHub tokens typically use `8 * 60 * 60` seconds), or `GitHubTokenProviderResult.Cancel()`. Cannot be combined with `GitHubToken`.
 - `SkillProvider` - Experimental session-scoped skill provider. See [Skill providers (experimental)](#skill-providers-experimental).
 - `OnPermissionRequest` - Optional handler called before each tool execution to approve or deny it. When omitted, permission requests are emitted as events and left pending for manual resolution. `PermissionHandler.ApproveAll` approves requests when managed settings are disabled and throws when `EnableManagedSettings` is true. Custom handlers can inspect `ManagedApprovalRequired` for human-facing confirmation logic. See [Permission Handling](#permission-handling) section.
 
@@ -1305,7 +1305,6 @@ public async Task<CopilotSession> CreateSessionAsync(SessionConfig config, Cance
                 config.EnableFileHooks,
                 config.EnableHostGitOperations,
                 config.EnableSessionStore,
-                config.EnableGitHubCacheStore,
                 config.EnableSkills,
                 config.SkillDirectories,
                 config.DisabledSkills,
@@ -1321,6 +1320,13 @@ public async Task<CopilotSession> CreateSessionAsync(SessionConfig config, Cance
                 GitHubTokenProviderRegistrationId: registrationId,
                 RemoteSession: config.RemoteSession,
                 Cloud: config.Cloud,
+                TrustWorkingDirectory: config.TrustWorkingDirectory switch
+                {
+                    WorkingDirectoryTrust.Session => "session",
+                    WorkingDirectoryTrust.User => "user",
+                    null => null,
+                    _ => throw new ArgumentOutOfRangeException(nameof(config), config.TrustWorkingDirectory, "Unsupported working-directory trust scope.")
+                },
                 RefreshCustomInstructions: config.RefreshCustomInstructions,
                 InstructionDirectories: config.InstructionDirectories,
                 AgentDirectories: config.AgentDirectories,
@@ -1572,7 +1578,6 @@ public async Task<CopilotSession> ResumeSessionAsync(string sessionId, ResumeSes
                 config.EnableFileHooks,
                 config.EnableHostGitOperations,
                 config.EnableSessionStore,
-                config.EnableGitHubCacheStore,
                 config.EnableSkills,
                 config.SuppressResumeEvent is true ? true : null,
                 config.Streaming is true ? true : null,
@@ -3276,7 +3281,6 @@ internal record CreateSessionRequest(
         bool? EnableFileHooks,
         bool? EnableHostGitOperations,
         bool? EnableSessionStore,
-        [property: JsonPropertyName("enableGitHubCacheStore")] bool? EnableGitHubCacheStore,
         bool? EnableSkills,
         IList<string>? SkillDirectories,
         IList<string>? DisabledSkills,
@@ -3292,6 +3296,7 @@ internal record CreateSessionRequest(
         [property: JsonPropertyName("gitHubTokenProviderRegistrationId")] string? GitHubTokenProviderRegistrationId = null,
         RemoteSessionMode? RemoteSession = null,
         CloudSessionOptions? Cloud = null,
+        string? TrustWorkingDirectory = null,
         bool? RefreshCustomInstructions = null,
         IList<string>? InstructionDirectories = null,
         IList<string>? AgentDirectories = null,
@@ -3332,7 +3337,8 @@ internal record ToolDefinition(
         bool? SkipPermission = null,
         CopilotToolDefer? Defer = null,
         IDictionary<string, JsonNode?>? Metadata = null,
-        bool? IsTerminal = null)
+        bool? IsTerminal = null,
+        ProtocolExternalToolNamespace? Namespace = null)
     {
         public static ToolDefinition FromAIFunction(AIFunctionDeclaration function)
         {
@@ -3341,12 +3347,16 @@ public static ToolDefinition FromAIFunction(AIFunctionDeclaration function)
             var defer = function.AdditionalProperties.TryGetValue(CopilotTool.DeferKey, out var deferVal) && deferVal is CopilotToolDefer d ? d : (CopilotToolDefer?)null;
             var metadata = function.AdditionalProperties.TryGetValue(CopilotTool.MetadataKey, out var metaVal) && metaVal is IDictionary<string, JsonNode?> m ? m : null;
             var isTerminal = function.AdditionalProperties.TryGetValue(CopilotTool.IsTerminalKey, out var terminalVal) && terminalVal is true;
+            var toolNamespace = function.AdditionalProperties.TryGetValue(CopilotTool.NamespaceKey, out var namespaceVal) && namespaceVal is ToolNamespace ns
+                ? new ProtocolExternalToolNamespace { Name = ns.Name, Description = ns.Description }
+                : null;
             return new ToolDefinition(function.Name, function.Description, function.JsonSchema,
                 overrides ? true : null,
                 skipPerm ? true : null,
                 defer,
                 metadata,
-                isTerminal ? true : null);
+                isTerminal ? true : null,
+                toolNamespace);
         }
     }
 
@@ -3393,7 +3403,6 @@ internal record ResumeSessionRequest(
         bool? EnableFileHooks,
         bool? EnableHostGitOperations,
         bool? EnableSessionStore,
-        [property: JsonPropertyName("enableGitHubCacheStore")] bool? EnableGitHubCacheStore,
         bool? EnableSkills,
         [property: JsonPropertyName("disableResume")] bool? SuppressResumeEvent,
         bool? Streaming,
 
@@ -3,6 +3,7 @@
  *--------------------------------------------------------------------------------------------*/
 
 using Microsoft.Extensions.AI;
+using System.Diagnostics.CodeAnalysis;
 using System.Text.Json.Nodes;
 
 namespace GitHub.Copilot;
@@ -27,6 +28,9 @@ public static class CopilotTool
     /// <summary>The key used in <see cref="AITool.AdditionalProperties"/> to carry the tool's opaque host-defined metadata.</summary>
     internal const string MetadataKey = "metadata";
 
+    /// <summary>The key used in <see cref="AITool.AdditionalProperties"/> to carry the tool's <see cref="ToolNamespace"/>.</summary>
+    internal const string NamespaceKey = "namespace";
+
     /// <summary>
     /// Defines a tool for use in a <see cref="CopilotSession"/>.
     /// </summary>
@@ -94,7 +98,7 @@ static void ApplyToolInvocationBinding(AIFunctionFactoryOptions factoryOptions)
 
         static void ApplyToolOptions(AIFunctionFactoryOptions factoryOptions, CopilotToolOptions? toolOptions)
         {
-            if (toolOptions is not null && (toolOptions.OverridesBuiltInTool || toolOptions.SkipPermission || toolOptions.IsTerminal || toolOptions.Defer is not null || toolOptions.Metadata is not null))
+            if (toolOptions is not null && (toolOptions.OverridesBuiltInTool || toolOptions.SkipPermission || toolOptions.IsTerminal || toolOptions.Defer is not null || toolOptions.Metadata is not null || toolOptions.Namespace is not null))
             {
                 Dictionary<string, object?> additionalProperties = new(StringComparer.Ordinal);
                 if (factoryOptions.AdditionalProperties is not null)
@@ -130,6 +134,11 @@ static void ApplyToolOptions(AIFunctionFactoryOptions factoryOptions, CopilotToo
                     additionalProperties[MetadataKey] = metadata;
                 }
 
+                if (toolOptions.Namespace is { } toolNamespace)
+                {
+                    additionalProperties[NamespaceKey] = toolNamespace;
+                }
+
                 factoryOptions.AdditionalProperties = additionalProperties;
             }
         }
@@ -183,6 +192,34 @@ public sealed class CopilotToolOptions
     /// Gets or sets opaque, host-defined metadata associated with the tool definition.
     /// </summary>
     public IDictionary<string, JsonNode?>? Metadata { get; set; }
+
+    /// <summary>
+    /// Gets or sets an optional namespace grouping this tool with related tools for model tool discovery.
+    /// </summary>
+    /// <remarks>
+    /// Where the model provider supports native tool namespaces, deferred tools sharing a namespace are presented to
+    /// the model as one group; elsewhere the tool stays flat. The tool keeps its unique name either way.
+    /// The resulting <see cref="AIFunction"/> carries the value in its <see cref="AITool.AdditionalProperties"/>.
+    /// </remarks>
+    [Experimental(Diagnostics.Experimental)]
+    public ToolNamespace? Namespace { get; set; }
+}
+
+/// <summary>
+/// Groups related tools for model tool discovery.
+/// </summary>
+[Experimental(Diagnostics.Experimental)]
+public sealed class ToolNamespace
+{
+    /// <summary>
+    /// Gets or sets the namespace name: 1-64 ASCII letters, digits, underscores, or hyphens.
+    /// </summary>
+    public string Name { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets an optional model-visible explanation of the tools in this namespace.
+    /// </summary>
+    public string? Description { get; set; }
 }
 
 /// <summary>