fix(api): accept null legacy event context

Allow event responses with explicitly null extra data to load issue details while retaining validation of arrays, scalars, and other event fields.

Co-Authored-By: Codex (GPT-6) <noreply@openai.com>

Author: betegon

docs/contributing/tool-responses.md

@@ -125,6 +125,10 @@ omits the section. Commit lookup is optional: failures do not prevent issue
 details from loading, but unexpected server or response-validation failures
 are reported to Sentry.
 
+The event API's legacy `context` field (extra data) can be `null`. Issue details
+must still load; omit the `Extra Data` section for null or empty values while
+preserving the event's error, stacktrace, and structured `contexts` data.
+
 ## Structured Content
 
 MCP tools may expose `structuredContent` alongside generated text `content`.

packages/mcp-core/src/api-client/client-event.test.ts

@@ -33,12 +33,12 @@ describe("getEventForIssue context validation", () => {
   });
 
   it.each([
-    { context: null, contextType: "null" },
     { context: ["private-extra-value"], contextType: "array" },
     { context: "private-extra-value", contextType: "string" },
     { context: 12345, contextType: "number" },
     { context: false, contextType: "boolean" },
     // Valid context can accompany a failure in another field.
+    { context: null, contextType: "null", title: null },
     { context: undefined, contextType: "undefined", title: null },
     {
       context: { "private-extra-key": "private-extra-value" },
@@ -68,6 +68,7 @@ describe("getEventForIssue context validation", () => {
 
   it.each([
     undefined,
+    null,
     {},
     { array: [1, "two"], nested: { value: false }, nullable: null },
   ])("preserves valid context: %j", async (context) => {

packages/mcp-core/src/api-client/schema.ts

@@ -1133,7 +1133,8 @@ const BaseEventSchema = z.object({
     .optional(),
   // "context" (singular) is the legacy "extra" field for arbitrary user-defined data
   // This is different from "contexts" (plural) which are structured contexts
-  context: z.record(z.string(), z.unknown()).optional(),
+  // Sentry preserves null when the event's extra data is explicitly null.
+  context: z.record(z.string(), z.unknown()).nullable().optional(),
   sdk: z
     .object({
       name: z.string().nullable().optional(),

packages/mcp-core/src/tools/catalog/get-issue-details.test.ts

@@ -8,6 +8,7 @@ import {
   createRegressedIssue,
   createUnknownEvent,
   createUnsupportedIssue,
+  eventFixture,
   issueNullCulpritFixture,
   mswServer,
 } from "@sentry/mcp-server-mocks";
@@ -2055,6 +2056,37 @@ describe("get_issue_details", () => {
     expect(result).toContain("### Additional Context");
   });
 
+  it("returns event details when legacy context is null", async () => {
+    mswServer.use(
+      http.get(
+        "https://sentry.io/api/0/organizations/sentry-mcp-evals/issues/6507376925/events/latest/",
+        () => HttpResponse.json({ ...eventFixture, context: null }),
+        { once: true },
+      ),
+    );
+
+    const result = await getIssueDetails.handler(
+      {
+        organizationSlug: "sentry-mcp-evals",
+        issueId: "CLOUDFLARE-MCP-41",
+        eventId: undefined,
+        issueUrl: undefined,
+        regionUrl: null,
+      },
+      baseContext,
+    );
+
+    expect(result).toContain("## Event Details");
+    expect(result).toContain(`**Event ID**: ${eventFixture.id}`);
+    expect(result).toContain(
+      "Error: Tool list_organizations is already registered",
+    );
+    expect(result).toContain("index.js:19631:28 (Object.fetch)");
+    expect(result).toContain("### Additional Context");
+    expect(result).toContain('name: "cloudflare"');
+    expect(result).not.toContain("### Extra Data");
+  });
+
   it("handles regressed performance issues (generic type with empty entries)", async () => {
     // This tests the actual structure from issue #633
     // Regressed performance issues have: