Add PostHog native hosted MCP entry (TASK-243)

backend/__tests__/unit/integrations/posthogHostedMcp.test.js

@@ -0,0 +1,37 @@
+const { POSTHOG_ENTRY } = require('../../../integrations/hostedMcp/posthog');
+const { HOSTED_MCP_ENTRIES } = require('../../../integrations/hostedMcp/entries');
+const { assessEntryTools, canonicalJson } = require('../../../services/hostedMcpEntryService');
+const capture = require('../../fixtures/hostedMcp/posthog-selected-tools-2026-10-21.json');
+
+test('PostHog registers only the selected native tools from the consenting tools-mode capture', () => {
+  expect(HOSTED_MCP_ENTRIES).toContain(POSTHOG_ENTRY);
+  expect(capture.server).toBe(POSTHOG_ENTRY.resource);
+  expect(POSTHOG_ENTRY.audience).toBe('https://mcp.posthog.com/mcp');
+  expect(capture.toolCountInFullCapture).toBe(780);
+  expect(capture.requestedScope).toBeNull(); // Scope narrowing needs its own consent check.
+  expect(POSTHOG_ENTRY.tools.map((tool) => tool.upstreamName)).toEqual(capture.tools.map((tool) => tool.name));
+  expect(POSTHOG_ENTRY.tools).toHaveLength(9);
+  expect(POSTHOG_ENTRY.tools.filter((tool) => tool.class === 'read')).toHaveLength(7);
+  expect(POSTHOG_ENTRY.tools.filter((tool) => tool.class === 'write')).toHaveLength(2);
+  expect(POSTHOG_ENTRY.tools.some((tool) => tool.name === 'exec' || tool.name === 'execute-sql')).toBe(false);
+
+  for (const [index, pin] of POSTHOG_ENTRY.tools.entries()) {
+    const measured = capture.tools[index];
+    expect(canonicalJson(pin.inputSchema)).toBe(canonicalJson(measured.inputSchema));
+    expect(pin.annotations).toEqual({
+      readOnlyHint: measured.annotations.readOnlyHint,
+      destructiveHint: measured.annotations.destructiveHint,
+    });
+    expect(pin.class).toBe(measured.annotations.readOnlyHint ? 'read' : 'write');
+  }
+  expect(assessEntryTools(POSTHOG_ENTRY, capture.tools).every((result) => result.verdict === 'ok')).toBe(true);
+});
+
+test('a moved PostHog write schema or withdrawn read claim withholds that pin', () => {
+  const changed = structuredClone(capture.tools);
+  changed.find((tool) => tool.name === 'dashboard-create').inputSchema.required = ['name', 'unknown'];
+  changed.find((tool) => tool.name === 'insights-list').annotations.readOnlyHint = false;
+  const verdicts = new Map(assessEntryTools(POSTHOG_ENTRY, changed).map((item) => [item.name, item.verdict]));
+  expect(verdicts.get('dashboard-create')).toBe('tool_drift');
+  expect(verdicts.get('insights-list')).toBe('tool_drift');
+});

backend/__tests__/unit/services/hostedMcpEntry.test.js

@@ -567,7 +567,9 @@ describe('the shipped catalogue cannot land half-wired', () => {
   test('ships Linear, Google Calendar, Atlassian, then Airtable, and lookup names the requested entry', () => {
     // The catalogue is the one place that says what an instance offers before
     // any member has connected anything. Its ordering follows the build plan.
-    expect(HOSTED_MCP_ENTRIES.map((entry) => entry.id)).toEqual(['linear', 'google-calendar', 'atlassian', 'airtable']);
+    expect(HOSTED_MCP_ENTRIES.map((entry) => entry.id)).toEqual([
+      'linear', 'google-calendar', 'atlassian', 'airtable', 'posthog',
+    ]);
     const catalogue = [linear(), linear({ id: 'notion', title: 'Notion' })];
     expect(findHostedMcpEntry(catalogue, 'notion').title).toBe('Notion');
     expect(findHostedMcpEntry(catalogue, 'linear').title).toBe('Linear');

backend/__tests__/unit/services/hostedMcpToolDefinitions.test.js

@@ -11,6 +11,7 @@
  */
 const {
   HOSTED_MCP_CALL_TIMEOUT_MS,
+  HOSTED_MCP_LIST_MAX_BYTES,
   createHostedMcpRuntimeDriftCache,
   hostedToolDefinitions,
   findHostedToolDefinition,
@@ -137,6 +138,42 @@ describe('hosted-MCP tool definitions', () => {
     expect(JSON.parse(deps.fetcher.mock.calls[0][1].body).method).toBe('tools/list');
   });
 
+  it('refuses an oversized JSON tools/list body before parsing or calling a tool', async () => {
+    const reply = JSON.stringify({ jsonrpc: '2.0', id: 'list-1', result: { tools: [{
+      name: 'list_issues', inputSchema: ENTRY.tools[0].inputSchema,
+    }] } });
+    const body = new TextEncoder().encode(reply + ' '.repeat(HOSTED_MCP_LIST_MAX_BYTES));
+    const deps = makeDeps({
+      fetcher: jest.fn(async () => new Response(body, {
+        headers: { 'content-type': 'application/json' },
+      })),
+    });
+    deps.driftCache = createHostedMcpRuntimeDriftCache(deps, [ENTRY]);
+    await expect(definitionFor('linear.list_issues', deps).call({}, CONNECTION))
+      .rejects.toMatchObject({ code: 'provider_error', message: expect.stringContaining('could not be verified') });
+    expect(deps.fetcher).toHaveBeenCalledTimes(1);
+  });
+
+  it('shares the byte budget across SSE tools/list pages', async () => {
+    const first = `data: ${JSON.stringify({
+      jsonrpc: '2.0', id: 'list-1', result: { tools: [], nextCursor: 'page-2' },
+    })}\n${' '.repeat(Math.floor(HOSTED_MCP_LIST_MAX_BYTES / 2))}`;
+    const second = `data: ${JSON.stringify({
+      jsonrpc: '2.0', id: 'list-2', result: { tools: [{
+        name: 'list_issues', inputSchema: ENTRY.tools[0].inputSchema,
+      }] },
+    })}\n${' '.repeat(Math.floor(HOSTED_MCP_LIST_MAX_BYTES / 2))}`;
+    const deps = makeDeps({
+      fetcher: jest.fn(async (_url, init) => sseResponse([
+        JSON.parse(init.body).params.cursor ? second : first,
+      ])),
+    });
+    deps.driftCache = createHostedMcpRuntimeDriftCache(deps, [ENTRY]);
+    await expect(definitionFor('linear.list_issues', deps).call({}, CONNECTION))
+      .rejects.toMatchObject({ code: 'provider_error', message: expect.stringContaining('could not be verified') });
+    expect(deps.fetcher).toHaveBeenCalledTimes(2);
+  });
+
   it('offers nothing when the catalogue is empty, and one definition per pinned tool otherwise', () => {
     expect(hostedToolDefinitions([], makeDeps())).toHaveLength(0);
     const definitions = hostedToolDefinitions([ENTRY], makeDeps());

backend/integrations/hostedMcp/entries.ts

@@ -16,8 +16,11 @@ import { AIRTABLE_ENTRY } from './airtable';
 import { ATLASSIAN_ENTRY } from './atlassian';
 import { GOOGLE_CALENDAR_ENTRY } from './googleCalendar';
 import { LINEAR_ENTRY } from './linear';
+import { POSTHOG_ENTRY } from './posthog';
 
-export const HOSTED_MCP_ENTRIES: HostedMcpEntry[] = [LINEAR_ENTRY, GOOGLE_CALENDAR_ENTRY, ATLASSIAN_ENTRY, AIRTABLE_ENTRY];
+export const HOSTED_MCP_ENTRIES: HostedMcpEntry[] = [
+  LINEAR_ENTRY, GOOGLE_CALENDAR_ENTRY, ATLASSIAN_ENTRY, AIRTABLE_ENTRY, POSTHOG_ENTRY,
+];
 
 /**
  * Seven entry-local defects that would otherwise be silent, checked at module