Add session-level canvasProvider field to Rust, Node, .NET, Go, and Python SDKs (#1847)

* Add session-level canvasProvider field to Rust, Node, and .NET SDKs

Hosts can now supply a stable canvas-provider identity { id, name? } on
session.create and session.resume so host-provided canvases restore
across cold resume. Serializes as canvasProvider on the wire, mirroring
the existing extensionInfo field. Implements the runtime contract from
github/copilot-agent-runtime#10519.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

* Assert canvasProvider.name key is absent, not just null

Indexing with ["name"] returns Value::Null both when the key is absent
and when it is present as null. Since the wire contract omits name when
None, assert the key is not present to catch a regression that would
serialize name: null.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

* Add canvasProvider to Go and Python SDKs

Extend the session-level canvasProvider field to the Go and Python SDKs
for parity with Rust, Node, and .NET. Hosts can now send a stable
canvas-provider identity ({ id, name? }) on session.create and
session.resume so host-provided canvases restore across cold resume.

Go: add CanvasProviderIdentity, wire it onto SessionConfig,
ResumeSessionConfig, and both request structs, and forward it in
client.go. Also fix a pre-existing gap where ExtensionInfo was declared
but never forwarded on create/resume.

Python: add CanvasProviderIdentity dataclass, export it, and forward a
canvas_provider param on create_session/resume_session.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

Author: jmoseley

dotnet/src/Canvas.cs

@@ -57,6 +57,32 @@ public sealed class ExtensionInfo
     public string Name { get; set; } = string.Empty;
 }
 
+/// <summary>
+/// Stable identity for a host/SDK connection that supplies built-in canvases.
+/// </summary>
+/// <remarks>
+/// When set on session create or resume, the runtime uses <see cref="Id"/>
+/// verbatim as the agent-facing canvas extension id, so canvases declared on a
+/// control connection survive stdio reconnect and CLI process restart instead
+/// of being re-keyed to a per-connection id. The id is opaque to the runtime; a
+/// per-window-stable value such as <c>app:builtin:&lt;windowId&gt;</c> is
+/// recommended. An id beginning with <c>connection:</c> is reserved and ignored
+/// by the runtime.
+/// </remarks>
+[Experimental(Diagnostics.Experimental)]
+public sealed class CanvasProviderIdentity
+{
+    /// <summary>
+    /// Opaque, stable provider id used verbatim as the canvas extension id.
+    /// </summary>
+    [JsonPropertyName("id")]
+    public string Id { get; set; } = string.Empty;
+
+    /// <summary>Optional display name surfaced as the canvas extension name.</summary>
+    [JsonPropertyName("name")]
+    public string? Name { get; set; }
+}
+
 /// <summary>Structured exception returned from canvas handlers.</summary>
 /// <remarks>
 /// Throw this from <see cref="ICanvasHandler"/> implementations to surface a

dotnet/src/Client.cs

@@ -1143,6 +1143,7 @@ public async Task<CopilotSession> CreateSessionAsync(SessionConfig config, Cance
                 RequestExtensions: config.RequestExtensions,
                 ExtensionSdkPath: config.ExtensionSdkPath,
                 ExtensionInfo: config.ExtensionInfo,
+                CanvasProvider: config.CanvasProvider,
                 Providers: config.Providers,
                 Models: config.Models,
                 ToolFilterPrecedence: toolFilter.ToolFilterPrecedence,
@@ -1353,6 +1354,7 @@ public async Task<CopilotSession> ResumeSessionAsync(string sessionId, ResumeSes
                 RequestExtensions: config.RequestExtensions,
                 ExtensionSdkPath: config.ExtensionSdkPath,
                 ExtensionInfo: config.ExtensionInfo,
+                CanvasProvider: config.CanvasProvider,
                 OpenCanvases: config.OpenCanvases,
                 Providers: config.Providers,
                 Models: config.Models,
@@ -2694,6 +2696,7 @@ internal record CreateSessionRequest(
         bool? RequestExtensions = null,
         string? ExtensionSdkPath = null,
         ExtensionInfo? ExtensionInfo = null,
+        CanvasProviderIdentity? CanvasProvider = null,
         IList<NamedProviderConfig>? Providers = null,
         IList<ProviderModelConfig>? Models = null,
         OptionsUpdateToolFilterPrecedence? ToolFilterPrecedence = null,
@@ -2794,6 +2797,7 @@ internal record ResumeSessionRequest(
         bool? RequestExtensions = null,
         string? ExtensionSdkPath = null,
         ExtensionInfo? ExtensionInfo = null,
+        CanvasProviderIdentity? CanvasProvider = null,
         IList<OpenCanvasInstance>? OpenCanvases = null,
         IList<NamedProviderConfig>? Providers = null,
         IList<ProviderModelConfig>? Models = null,

dotnet/src/Types.cs

@@ -2868,6 +2868,7 @@ protected SessionConfigBase(SessionConfigBase? other)
         RequestExtensions = other.RequestExtensions;
         ExtensionSdkPath = other.ExtensionSdkPath;
         ExtensionInfo = other.ExtensionInfo;
+        CanvasProvider = other.CanvasProvider;
         CanvasHandler = other.CanvasHandler;
 #pragma warning restore GHCP001
         SkillDirectories = other.SkillDirectories is not null ? [.. other.SkillDirectories] : null;
@@ -3337,6 +3338,16 @@ protected SessionConfigBase(SessionConfigBase? other)
     [Experimental(Diagnostics.Experimental)]
     public ExtensionInfo? ExtensionInfo { get; set; }
 
+    /// <summary>
+    /// Stable identity for a host/SDK connection that supplies built-in
+    /// canvases. When set, the runtime uses <see cref="CanvasProviderIdentity.Id"/>
+    /// verbatim as the agent-facing canvas extension id, so canvases declared on
+    /// a control connection survive reconnect and CLI restart. Honored on
+    /// session create and resume.
+    /// </summary>
+    [Experimental(Diagnostics.Experimental)]
+    public CanvasProviderIdentity? CanvasProvider { get; set; }
+
     /// <summary>
     /// Provider-side canvas lifecycle handler. The SDK routes inbound
     /// <c>canvas.open</c> / <c>canvas.close</c> / <c>canvas.action.invoke</c>
@@ -4021,5 +4032,6 @@ public sealed class SystemMessageTransformRpcResponse
 [JsonSerializable(typeof(CanvasProviderOpenResult))]
 [JsonSerializable(typeof(CanvasHostContext))]
 [JsonSerializable(typeof(ExtensionInfo))]
+[JsonSerializable(typeof(CanvasProviderIdentity))]
 #pragma warning restore GHCP001
 internal partial class TypesJsonContext : JsonSerializerContext;

dotnet/test/Unit/CanvasTests.cs

@@ -313,6 +313,28 @@ public void ExtensionInfo_Serializes_SourceAndName()
         Assert.Equal("demo", doc.RootElement.GetProperty("name").GetString());
     }
 
+    [Fact]
+    public void CanvasProviderIdentity_Serializes_IdAndName()
+    {
+        var options = GetSerializerOptions();
+        var identity = new CanvasProviderIdentity { Id = "app:builtin:window-1", Name = "Built-in" };
+        var json = JsonSerializer.Serialize(identity, options);
+        using var doc = JsonDocument.Parse(json);
+        Assert.Equal("app:builtin:window-1", doc.RootElement.GetProperty("id").GetString());
+        Assert.Equal("Built-in", doc.RootElement.GetProperty("name").GetString());
+    }
+
+    [Fact]
+    public void CanvasProviderIdentity_OmitsNullName()
+    {
+        var options = GetSerializerOptions();
+        var identity = new CanvasProviderIdentity { Id = "app:builtin:window-1" };
+        var json = JsonSerializer.Serialize(identity, options);
+        using var doc = JsonDocument.Parse(json);
+        Assert.Equal("app:builtin:window-1", doc.RootElement.GetProperty("id").GetString());
+        Assert.False(doc.RootElement.TryGetProperty("name", out _));
+    }
+
     [Fact]
     public async Task CanvasHandlerBase_DefaultOnClose_Completes()
     {
@@ -348,6 +370,7 @@ public void SessionConfig_Clone_CopiesCanvasFields()
             RequestCanvasRenderer = true,
             RequestExtensions = true,
             ExtensionInfo = new ExtensionInfo { Source = "github-app", Name = "demo" },
+            CanvasProvider = new CanvasProviderIdentity { Id = "app:builtin:window-1", Name = "Built-in" },
             CanvasHandler = handler
         };
 
@@ -360,6 +383,8 @@ public void SessionConfig_Clone_CopiesCanvasFields()
         Assert.True(clone.RequestExtensions);
         Assert.NotNull(clone.ExtensionInfo);
         Assert.Equal("github-app", clone.ExtensionInfo!.Source);
+        Assert.NotNull(clone.CanvasProvider);
+        Assert.Equal("app:builtin:window-1", clone.CanvasProvider!.Id);
         Assert.Same(handler, clone.CanvasHandler);
 
         // Mutating the clone's list does not affect the original.
@@ -376,6 +401,7 @@ public void ResumeSessionConfig_Clone_CopiesCanvasFields()
             Canvases = new[] { new CanvasDeclaration { Id = "c1", DisplayName = "C", Description = "d" } },
             RequestCanvasRenderer = true,
             ExtensionInfo = new ExtensionInfo { Source = "s", Name = "n" },
+            CanvasProvider = new CanvasProviderIdentity { Id = "app:builtin:window-2" },
             CanvasHandler = handler
         };
 
@@ -385,6 +411,8 @@ public void ResumeSessionConfig_Clone_CopiesCanvasFields()
         Assert.Single(clone.Canvases!);
         Assert.True(clone.RequestCanvasRenderer);
         Assert.NotNull(clone.ExtensionInfo);
+        Assert.NotNull(clone.CanvasProvider);
+        Assert.Equal("app:builtin:window-2", clone.CanvasProvider!.Id);
         Assert.Same(handler, clone.CanvasHandler);
     }
 

go/canvas.go

@@ -42,6 +42,24 @@ type ExtensionInfo struct {
 	Name string `json:"name"`
 }
 
+// CanvasProviderIdentity is the stable identity for a host/SDK connection
+// that supplies built-in canvases.
+//
+// When set on session create or resume, the runtime uses ID verbatim as the
+// agent-facing canvas extension id, so host-provided canvases survive
+// reconnect and CLI restart.
+//
+// Experimental: CanvasProviderIdentity is part of an experimental
+// wire-protocol surface and may change or be removed in future SDK or CLI
+// releases.
+type CanvasProviderIdentity struct {
+	// ID is an opaque, stable provider id used verbatim as the canvas
+	// extension id.
+	ID string `json:"id"`
+	// Name is an optional display name surfaced as the canvas extension name.
+	Name *string `json:"name,omitempty"`
+}
+
 // CanvasError is a structured error returned from canvas handlers.
 //
 // Wire envelope:

go/client.go

@@ -727,6 +727,8 @@ func (c *Client) CreateSession(ctx context.Context, config *SessionConfig) (*Ses
 	req.RemoteSession = config.RemoteSession
 	req.Cloud = config.Cloud
 	req.Canvases = config.Canvases
+	req.ExtensionInfo = config.ExtensionInfo
+	req.CanvasProvider = config.CanvasProvider
 	req.RequestCanvasRenderer = config.RequestCanvasRenderer
 	req.RequestExtensions = config.RequestExtensions
 	req.ExtensionSDKPath = config.ExtensionSDKPath
@@ -1091,6 +1093,8 @@ func (c *Client) ResumeSessionWithOptions(ctx context.Context, sessionID string,
 	req.RemoteSession = config.RemoteSession
 	req.Canvases = config.Canvases
 	req.OpenCanvases = config.OpenCanvases
+	req.ExtensionInfo = config.ExtensionInfo
+	req.CanvasProvider = config.CanvasProvider
 	req.RequestCanvasRenderer = config.RequestCanvasRenderer
 	req.RequestExtensions = config.RequestExtensions
 	req.ExtensionSDKPath = config.ExtensionSDKPath

go/client_test.go

@@ -251,6 +251,82 @@ func TestClient_ForwardsCapiOptionsToSessionRequests(t *testing.T) {
 	assertCapiEnableWebSocketResponses(t, <-resumeParams)
 }
 
+func TestClient_ForwardsCanvasProviderToSessionRequests(t *testing.T) {
+	rpcClient, server, _ := newRuntimeShutdownRpcPair(t)
+	t.Cleanup(server.Stop)
+	client := &Client{
+		client:   rpcClient,
+		RPC:      rpc.NewServerRPC(rpcClient),
+		sessions: make(map[string]*Session),
+	}
+
+	createParams := make(chan json.RawMessage, 1)
+	server.SetRequestHandler("session.create", func(params json.RawMessage) (json.RawMessage, *jsonrpc2.Error) {
+		createParams <- append(json.RawMessage(nil), params...)
+		sessionID := sessionIDFromParams(t, params)
+		return []byte(`{"sessionId":"` + sessionID + `","workspacePath":"/workspace"}`), nil
+	})
+
+	_, err := client.CreateSession(t.Context(), &SessionConfig{
+		ExtensionInfo:  &ExtensionInfo{Source: "github-app", Name: "counter-provider"},
+		CanvasProvider: &CanvasProviderIdentity{ID: "app:builtin:window-1", Name: String("Built-in")},
+	})
+	if err != nil {
+		t.Fatalf("CreateSession failed: %v", err)
+	}
+	assertCanvasProviderForwarded(t, <-createParams, "app:builtin:window-1", "Built-in", "counter-provider")
+
+	resumeParams := make(chan json.RawMessage, 1)
+	server.SetRequestHandler("session.resume", func(params json.RawMessage) (json.RawMessage, *jsonrpc2.Error) {
+		resumeParams <- append(json.RawMessage(nil), params...)
+		return []byte(`{"sessionId":"resumed-canvas","workspacePath":"/workspace"}`), nil
+	})
+
+	_, err = client.ResumeSessionWithOptions(t.Context(), "resumed-canvas", &ResumeSessionConfig{
+		CanvasProvider: &CanvasProviderIdentity{ID: "app:builtin:window-1"},
+	})
+	if err != nil {
+		t.Fatalf("ResumeSessionWithOptions failed: %v", err)
+	}
+	assertCanvasProviderForwarded(t, <-resumeParams, "app:builtin:window-1", "", "")
+}
+
+// assertCanvasProviderForwarded checks the outbound params carry canvasProvider
+// with the expected id. A non-empty wantName asserts the name is present; an
+// empty wantName asserts the name key is omitted from the wire. A non-empty
+// wantExtensionName asserts extensionInfo.name is forwarded alongside it.
+func assertCanvasProviderForwarded(t *testing.T, params json.RawMessage, wantID, wantName, wantExtensionName string) {
+	t.Helper()
+
+	var decoded map[string]any
+	if err := json.Unmarshal(params, &decoded); err != nil {
+		t.Fatalf("failed to unmarshal request params: %v", err)
+	}
+	provider, ok := decoded["canvasProvider"].(map[string]any)
+	if !ok {
+		t.Fatalf("expected canvasProvider object in request params, got %T", decoded["canvasProvider"])
+	}
+	if provider["id"] != wantID {
+		t.Fatalf("expected canvasProvider.id=%q, got %v", wantID, provider["id"])
+	}
+	if wantName == "" {
+		if _, present := provider["name"]; present {
+			t.Fatalf("expected canvasProvider.name to be omitted, got %v", provider["name"])
+		}
+	} else if provider["name"] != wantName {
+		t.Fatalf("expected canvasProvider.name=%q, got %v", wantName, provider["name"])
+	}
+	if wantExtensionName != "" {
+		info, ok := decoded["extensionInfo"].(map[string]any)
+		if !ok {
+			t.Fatalf("expected extensionInfo object in request params, got %T", decoded["extensionInfo"])
+		}
+		if info["name"] != wantExtensionName {
+			t.Fatalf("expected extensionInfo.name=%q, got %v", wantExtensionName, info["name"])
+		}
+	}
+}
+
 func TestClient_ForwardsNewSessionOptionsToSessionRequests(t *testing.T) {
 	rpcClient, server, _ := newRuntimeShutdownRpcPair(t)
 	t.Cleanup(server.Stop)

go/types.go

@@ -1235,6 +1235,9 @@ type SessionConfig struct {
 	CanvasHandler CanvasHandler `json:"-"`
 	// ExtensionInfo identifies the stable extension providing this session's canvases.
 	ExtensionInfo *ExtensionInfo
+	// CanvasProvider is the stable identity for a host/SDK connection that
+	// supplies built-in canvases, so they survive reconnect and CLI restart.
+	CanvasProvider *CanvasProviderIdentity
 	// ExpAssignments injects ExP assignment ("flight") data for this session,
 	// in the same JSON shape the Copilot CLI fetches from the experimentation
 	// service (CopilotExpAssignmentResponse). When supplied, the runtime feeds
@@ -1666,6 +1669,9 @@ type ResumeSessionConfig struct {
 	CanvasHandler CanvasHandler `json:"-"`
 	// ExtensionInfo identifies the stable extension providing this session's canvases.
 	ExtensionInfo *ExtensionInfo
+	// CanvasProvider is the stable identity for a host/SDK connection that
+	// supplies built-in canvases. See SessionConfig.CanvasProvider.
+	CanvasProvider *CanvasProviderIdentity
 	// ExpAssignments injects ExP assignment ("flight") data on resume. See
 	// SessionConfig.ExpAssignments. Re-supply on resume so the runtime
 	// re-applies the assignments after a CLI process restart.
@@ -2131,6 +2137,7 @@ type createSessionRequest struct {
 	RequestExtensions                  *bool                                  `json:"requestExtensions,omitempty"`
 	ExtensionSDKPath                   *string                                `json:"extensionSdkPath,omitempty"`
 	ExtensionInfo                      *ExtensionInfo                         `json:"extensionInfo,omitempty"`
+	CanvasProvider                     *CanvasProviderIdentity                `json:"canvasProvider,omitempty"`
 	ExpAssignments                     any                                    `json:"expAssignments,omitempty"`
 	EnableManagedSettings              *bool                                  `json:"enableManagedSettings,omitempty"`
 	Traceparent                        string                                 `json:"traceparent,omitempty"`
@@ -2221,6 +2228,7 @@ type resumeSessionRequest struct {
 	RequestExtensions                  *bool                                  `json:"requestExtensions,omitempty"`
 	ExtensionSDKPath                   *string                                `json:"extensionSdkPath,omitempty"`
 	ExtensionInfo                      *ExtensionInfo                         `json:"extensionInfo,omitempty"`
+	CanvasProvider                     *CanvasProviderIdentity                `json:"canvasProvider,omitempty"`
 	ExpAssignments                     any                                    `json:"expAssignments,omitempty"`
 	EnableManagedSettings              *bool                                  `json:"enableManagedSettings,omitempty"`
 	Traceparent                        string                                 `json:"traceparent,omitempty"`

nodejs/src/client.ts

@@ -1415,6 +1415,7 @@ export class CopilotClient {
                 requestExtensions: config.requestExtensions,
                 extensionSdkPath: config.extensionSdkPath,
                 extensionInfo: config.extensionInfo,
+                canvasProvider: config.canvasProvider,
                 commands: config.commands?.map((cmd) => ({
                     name: cmd.name,
                     description: cmd.description,
@@ -1632,6 +1633,7 @@ export class CopilotClient {
                 requestExtensions: config.requestExtensions,
                 extensionSdkPath: config.extensionSdkPath,
                 extensionInfo: config.extensionInfo,
+                canvasProvider: config.canvasProvider,
                 commands: config.commands?.map((cmd) => ({
                     name: cmd.name,
                     description: cmd.description,

nodejs/src/index.ts

@@ -51,6 +51,7 @@ export type {
     CommandContext,
     CommandDefinition,
     CommandHandler,
+    CanvasProviderIdentity,
     CloudSessionOptions,
     CloudSessionRepository,
     AutoModeSwitchHandler,