Persist MCP App success views across host remounts

pkg/github/pullrequests_test.go

@@ -2776,6 +2776,12 @@ func Test_CreatePullRequest_MCPAppsFeature_UIGate(t *testing.T) {
 		textContent := getTextResult(t, result)
 		assert.Contains(t, textContent.Text, "interactive form has been shown to the user for creating a new pull request")
 		assert.True(t, result.IsError, "form-routing stub should be marked IsError so agents don't claim success")
+
+		// github/github-mcp-server#2965: remount persistence keys off _meta.viewUUID.
+		require.NotNil(t, result.Meta, "deferral must include Meta for viewUUID")
+		viewUUID, ok := result.Meta["viewUUID"].(string)
+		require.True(t, ok, "viewUUID should be a string")
+		assert.NotEmpty(t, viewUUID)
 	})
 
 	t.Run("UI client with _ui_submitted executes directly", func(t *testing.T) {

pkg/utils/result.go

@@ -1,6 +1,12 @@
 package utils //nolint:revive //TODO: figure out a better name for this package
 
-import "github.com/modelcontextprotocol/go-sdk/mcp"
+import (
+	"crypto/rand"
+	"fmt"
+	"time"
+
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+)
 
 func NewToolResultText(message string) *mcp.CallToolResult {
 	return &mcp.CallToolResult{
@@ -69,6 +75,10 @@ func NewToolResultResourceLink(message string, link *mcp.ResourceLink) *mcp.Call
 // result. The MCP App form will submit the operation directly when the user
 // clicks submit, after which a ui/update-model-context call delivers the real
 // outcome to the agent.
+//
+// A stable Meta.viewUUID is included so MCP Apps can persist view state (e.g.
+// a completed success card) across host remounts via localStorage, per the
+// MCP Apps "Persisting view state" pattern.
 func NewToolResultAwaitingFormSubmission(message string) *mcp.CallToolResult {
 	return &mcp.CallToolResult{
 		Content: []mcp.Content{
@@ -81,5 +91,23 @@ func NewToolResultAwaitingFormSubmission(message string) *mcp.CallToolResult {
 			"reason": "An interactive form is being shown to the user. The operation has not been performed.",
 		},
 		IsError: true,
+		Meta: mcp.Meta{
+			"viewUUID": newViewUUID(),
+		},
+	}
+}
+
+// newViewUUID returns a random UUID v4 string without pulling in an extra
+// dependency. Used as the MCP Apps view persistence key.
+func newViewUUID() string {
+	var b [16]byte
+	if _, err := rand.Read(b[:]); err != nil {
+		// Extremely unlikely. Do not return a constant key (shared storage key →
+		// cross-view leakage); make it unique enough for a view persistence key.
+		return fmt.Sprintf("view-%d", time.Now().UnixNano())
 	}
+	// UUID version 4 + RFC 4122 variant bits.
+	b[6] = (b[6] & 0x0f) | 0x40
+	b[8] = (b[8] & 0x3f) | 0x80
+	return fmt.Sprintf("%x-%x-%x-%x-%x", b[0:4], b[4:6], b[6:8], b[8:10], b[10:])
 }

pkg/utils/result_test.go

@@ -0,0 +1,63 @@
+package utils
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/modelcontextprotocol/go-sdk/mcp"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestNewToolResultAwaitingFormSubmission_IncludesViewUUID(t *testing.T) {
+	t.Parallel()
+
+	result := NewToolResultAwaitingFormSubmission("showing form")
+	require.NotNil(t, result)
+	assert.True(t, result.IsError)
+	require.NotNil(t, result.Meta)
+
+	viewUUID, ok := result.Meta["viewUUID"].(string)
+	require.True(t, ok, "viewUUID should be a string")
+	assert.NotEmpty(t, viewUUID)
+	assert.Regexp(t, `^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$`, viewUUID)
+
+	status, ok := result.StructuredContent.(map[string]any)["status"]
+	require.True(t, ok)
+	assert.Equal(t, "awaiting_user_submission", status)
+}
+
+func TestNewToolResultAwaitingFormSubmission_UniqueViewUUIDs(t *testing.T) {
+	t.Parallel()
+
+	a := NewToolResultAwaitingFormSubmission("a")
+	b := NewToolResultAwaitingFormSubmission("b")
+	require.NotEqual(t, a.Meta["viewUUID"], b.Meta["viewUUID"])
+}
+
+// TestNewToolResultAwaitingFormSubmission_WireFormatMeta verifies the host-facing
+// JSON shape: MCP Apps read result._meta.viewUUID after the host re-delivers the
+// original deferral on remount (github/github-mcp-server#2965).
+func TestNewToolResultAwaitingFormSubmission_WireFormatMeta(t *testing.T) {
+	t.Parallel()
+
+	result := NewToolResultAwaitingFormSubmission("showing form")
+	raw, err := json.Marshal(result)
+	require.NoError(t, err)
+
+	var payload map[string]any
+	require.NoError(t, json.Unmarshal(raw, &payload))
+
+	meta, ok := payload["_meta"].(map[string]any)
+	require.True(t, ok, "wire JSON must include _meta; got: %s", string(raw))
+	viewUUID, ok := meta["viewUUID"].(string)
+	require.True(t, ok, "_meta.viewUUID must be a string; got: %s", string(raw))
+	assert.NotEmpty(t, viewUUID)
+	assert.Equal(t, true, payload["isError"])
+
+	// Round-trip: host re-sends the same JSON → UI must recover the same UUID.
+	var decoded mcp.CallToolResult
+	require.NoError(t, json.Unmarshal(raw, &decoded))
+	require.NotNil(t, decoded.Meta)
+	assert.Equal(t, viewUUID, decoded.Meta["viewUUID"])
+}

ui/package.json

@@ -11,6 +11,7 @@
     "build": "node scripts/build.mjs",
     "dev": "npm run build",
     "typecheck": "tsc --noEmit",
+    "test": "node --experimental-strip-types --test src/lib/viewState.test.ts",
     "clean": "rm -rf dist"
   },
   "dependencies": {

ui/src/apps/issue-write/App.tsx

@@ -25,6 +25,7 @@ import {
 import { AppProvider } from "../../components/AppProvider";
 import { useMcpApp } from "../../hooks/useMcpApp";
 import { completedToolResult } from "../../lib/toolResult";
+import { getViewUUID, loadViewState, saveViewState } from "../../lib/viewState";
 import { MarkdownEditor } from "../../components/MarkdownEditor";
 
 interface IssueResult {
@@ -449,7 +450,17 @@ function CreateIssueApp() {
   // null here, keeping the form for the normal deferred flow.
   // See github/copilot-mcp-core#1864.
   const resultIssue = useMemo(() => completedToolResult<IssueResult>(toolResult), [toolResult]);
-  const shownIssue = successIssue ?? resultIssue;
+  // Restore synchronously during render so a remount never paints the
+  // create/update form for a completed invocation (github/github-mcp-server#2965).
+  const persistedIssue = useMemo(() => {
+    if (successIssue || resultIssue) return null;
+    const viewUUID = getViewUUID(toolResult);
+    if (!viewUUID) return null;
+    return loadViewState<IssueResult, { submittedLabels?: LabelItem[] }>(viewUUID);
+  }, [successIssue, resultIssue, toolResult]);
+  const shownIssue = successIssue ?? resultIssue ?? persistedIssue?.result ?? null;
+  const shownSubmittedTitle = persistedIssue?.submittedTitle || title;
+  const shownSubmittedLabels = persistedIssue?.extras?.submittedLabels || selectedLabels;
 
   // Get method and issue_number from toolInput
   const method = (toolInput?.method as string) || "create";
@@ -1083,6 +1094,15 @@ function CreateIssueApp() {
           try {
             const issueData = JSON.parse(textContent.text as string);
             setSuccessIssue(issueData);
+            const viewUUID = getViewUUID(toolResult);
+            if (viewUUID) {
+              saveViewState(viewUUID, {
+                status: "completed",
+                result: issueData,
+                submittedTitle: title.trim(),
+                extras: { submittedLabels: selectedLabels },
+              });
+            }
             // Per the MCP Apps 2026-01-26 spec, push the created/updated issue
             // into the model's context so subsequent agent turns have it.
             void setModelContext({
@@ -1097,7 +1117,17 @@ function CreateIssueApp() {
               ],
             });
           } catch {
-            setSuccessIssue({ title, body });
+            const fallback = { title, body };
+            setSuccessIssue(fallback);
+            const viewUUID = getViewUUID(toolResult);
+            if (viewUUID) {
+              saveViewState(viewUUID, {
+                status: "completed",
+                result: fallback,
+                submittedTitle: title.trim(),
+                extras: { submittedLabels: selectedLabels },
+              });
+            }
           }
         }
       }
@@ -1123,6 +1153,7 @@ function CreateIssueApp() {
     fieldValues,
     issueFieldsByName,
     toolInput,
+    toolResult,
     callTool,
     setModelContext,
   ]);
@@ -1228,8 +1259,8 @@ function CreateIssueApp() {
         issue={shownIssue}
         owner={owner}
         repo={repo}
-        submittedTitle={title}
-        submittedLabels={selectedLabels}
+        submittedTitle={shownSubmittedTitle}
+        submittedLabels={shownSubmittedLabels}
         isUpdate={isUpdateMode}
         openLink={openLink}
       />

ui/src/apps/pr-edit/App.tsx

@@ -26,6 +26,7 @@ import {
 import { AppProvider } from "../../components/AppProvider";
 import { useMcpApp } from "../../hooks/useMcpApp";
 import { completedToolResult } from "../../lib/toolResult";
+import { getViewUUID, loadViewState, saveViewState } from "../../lib/viewState";
 import { MarkdownEditor } from "../../components/MarkdownEditor";
 
 interface PRResult {
@@ -283,7 +284,16 @@ function EditPRApp() {
   // (awaiting_user_submission) returns null here, keeping the form for the
   // normal deferred flow. See github/copilot-mcp-core#1864.
   const resultPR = useMemo(() => completedToolResult<PRResult>(toolResult), [toolResult]);
-  const shownPR = successPR ?? resultPR;
+  // Restore synchronously during render so a remount never paints the edit form
+  // for a completed invocation (github/github-mcp-server#2965).
+  const persistedPR = useMemo(() => {
+    if (successPR || resultPR) return null;
+    const viewUUID = getViewUUID(toolResult);
+    if (!viewUUID) return null;
+    return loadViewState<PRResult>(viewUUID);
+  }, [successPR, resultPR, toolResult]);
+  const shownPR = successPR ?? resultPR ?? persistedPR?.result ?? null;
+  const shownSubmittedTitle = submittedTitle || persistedPR?.submittedTitle || "";
 
   useEffect(() => {
     setTitle("");
@@ -487,6 +497,14 @@ function EditPRApp() {
         if (textContent && textContent.type === "text" && textContent.text) {
           const prData = JSON.parse(textContent.text);
           setSuccessPR(prData);
+          const viewUUID = getViewUUID(toolResult);
+          if (viewUUID) {
+            saveViewState(viewUUID, {
+              status: "completed",
+              result: prData,
+              submittedTitle: title.trim(),
+            });
+          }
           void setModelContext({
             structuredContent: prData,
             content: [
@@ -503,12 +521,12 @@ function EditPRApp() {
     } finally {
       setIsSubmitting(false);
     }
-  }, [title, body, owner, repo, pullNumber, baseBranch, initialValues, selectedReviewers, prState, isDraft, maintainerCanModify, callTool, setModelContext]);
+  }, [title, body, owner, repo, pullNumber, baseBranch, initialValues, selectedReviewers, prState, isDraft, maintainerCanModify, toolResult, callTool, setModelContext]);
 
   if (shownPR) {
     return (
       <AppProvider hostContext={hostContext}>
-        <SuccessView pr={shownPR} owner={owner} repo={repo} submittedTitle={submittedTitle} openLink={openLink} />
+        <SuccessView pr={shownPR} owner={owner} repo={repo} submittedTitle={shownSubmittedTitle} openLink={openLink} />
       </AppProvider>
     );
   }

ui/src/apps/pr-write/App.tsx

@@ -28,6 +28,7 @@ import {
 import { AppProvider } from "../../components/AppProvider";
 import { useMcpApp } from "../../hooks/useMcpApp";
 import { completedToolResult } from "../../lib/toolResult";
+import { getViewUUID, loadViewState, saveViewState } from "../../lib/viewState";
 import { MarkdownEditor } from "../../components/MarkdownEditor";
 
 interface PRResult {
@@ -206,7 +207,17 @@ function CreatePRApp() {
   // (awaiting_user_submission) returns null here, keeping the form for the
   // normal deferred flow. See github/copilot-mcp-core#1864.
   const resultPR = useMemo(() => completedToolResult<PRResult>(toolResult), [toolResult]);
-  const shownPR = successPR ?? resultPR;
+  // Restore synchronously during render so a remount never paints the create
+  // form for a completed invocation (github/github-mcp-server#2965). React
+  // success state and up-front (non-deferred) results take precedence.
+  const persistedPR = useMemo(() => {
+    if (successPR || resultPR) return null;
+    const viewUUID = getViewUUID(toolResult);
+    if (!viewUUID) return null;
+    return loadViewState<PRResult>(viewUUID);
+  }, [successPR, resultPR, toolResult]);
+  const shownPR = successPR ?? resultPR ?? persistedPR?.result ?? null;
+  const shownSubmittedTitle = submittedTitle || persistedPR?.submittedTitle || "";
 
   // Reset all transient form/result state when toolInput changes (new invocation).
   // Without this, the SuccessView from a previous submit stays visible and stale
@@ -431,6 +442,14 @@ function CreatePRApp() {
         if (textContent && textContent.type === "text" && textContent.text) {
           const prData = JSON.parse(textContent.text);
           setSuccessPR(prData);
+          const viewUUID = getViewUUID(toolResult);
+          if (viewUUID) {
+            saveViewState(viewUUID, {
+              status: "completed",
+              result: prData,
+              submittedTitle: title.trim(),
+            });
+          }
           // Push the new PR into the model context so subsequent agent
           // turns can reference it (MCP Apps 2026-01-26 ui/update-model-context).
           void setModelContext({
@@ -449,12 +468,12 @@ function CreatePRApp() {
     } finally {
       setIsSubmitting(false);
     }
-  }, [title, body, owner, repo, baseBranch, headBranch, isDraft, maintainerCanModify, selectedReviewers, toolInput, callTool, setModelContext]);
+  }, [title, body, owner, repo, baseBranch, headBranch, isDraft, maintainerCanModify, selectedReviewers, toolInput, toolResult, callTool, setModelContext]);
 
   if (shownPR) {
     return (
       <AppProvider hostContext={hostContext}>
-        <SuccessView pr={shownPR} owner={owner} repo={repo} submittedTitle={submittedTitle} openLink={openLink} />
+        <SuccessView pr={shownPR} owner={owner} repo={repo} submittedTitle={shownSubmittedTitle} openLink={openLink} />
       </AppProvider>
     );
   }