fix(api): accept null legacy event context (#1353)

Event responses can contain `context: null` for legacy extra data. MCP
rejected those responses before `get_issue_details` could return the
event's error and stacktrace.

Accept null in the shared event schema, preserve validation for records
and other fields, and keep the existing formatter behavior that omits
empty extra data. Regression tests cover the API client and
issue-details handler, including safe diagnostics for other validation
failures.

## Validation

- Both regressions fail before the fix and pass afterward; 113 focused
tests pass.
- `pnpm run tsc` and `pnpm run lint` pass.
- `pnpm run test` passes in Linux x64 with Node 24 and UTC.
- Documentation links and workspace CI selector tests pass.
- The packed stdio package installs in a clean consumer; typecheck and
runtime import pass.

The documentation update selects all workspace projects in CI,
exercising the monorepo build and package checks.

CI: all builds, MCP tests, CLI unit/E2E tests, CLI package/runtime
checks, and the clean stdio consumer pass. The CLI and CLI docs jobs
fail only their generated-file checks: the existing period-help
generator uses the current month in examples, changing ten generated
references. That date-dependent output is separate from this
event-schema fix.

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: