feat(tools): Add MCP Apps visualization support for search_events

Add interactive chart visualizations for aggregate query results using
the MCP Apps protocol. When search_events returns aggregate data, it now
includes structured chart data that MCP Apps-compatible clients can
render as bar, pie, line charts, tables, or single numbers.

Key changes:
- Create new mcp-apps-ui package with Chart.js-based visualization
- Extend ToolConfig with optional UI metadata for resource URIs
- Register UI resources in server for client fetching
- Enhance formatters to return chart data alongside text for aggregates
- Add chartType field to search_events agent for visualization hints

The implementation maintains backward compatibility - clients without
MCP Apps support continue to receive text responses.

Co-Authored-By: Claude <noreply@anthropic.com>

Author: dcramer

packages/mcp-apps-ui/package.json

@@ -0,0 +1,30 @@
+{
+  "name": "@sentry/mcp-apps-ui",
+  "version": "0.29.0",
+  "private": true,
+  "type": "module",
+  "license": "FSL-1.1-ALv2",
+  "description": "MCP Apps UI components for Sentry MCP - Interactive chart visualizations",
+  "files": ["./dist/*"],
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "default": "./dist/index.js"
+    }
+  },
+  "scripts": {
+    "build": "tsdown && vite build && tsx scripts/bundle-apps.ts",
+    "dev": "vite build --watch",
+    "tsc": "tsc --noEmit"
+  },
+  "devDependencies": {
+    "@sentry/mcp-server-tsconfig": "workspace:*",
+    "tsdown": "catalog:",
+    "vite": "catalog:",
+    "vite-plugin-singlefile": "^2.0.3"
+  },
+  "dependencies": {
+    "@modelcontextprotocol/ext-apps": "^0.4.0",
+    "chart.js": "^4.4.7"
+  }
+}

packages/mcp-apps-ui/scripts/bundle-apps.ts

@@ -0,0 +1,71 @@
+/**
+ * Post-build script that reads bundled HTML apps and generates
+ * TypeScript/JavaScript exports for consumption by other packages.
+ */
+
+import { readFileSync, writeFileSync, existsSync, mkdirSync } from "node:fs";
+import { join, dirname } from "node:path";
+
+const DIST_DIR = join(dirname(new URL(import.meta.url).pathname), "..", "dist");
+const APPS_DIR = join(DIST_DIR, "apps");
+
+// Map of app names to their bundled HTML file
+// Vite outputs HTML files in nested directories preserving the source structure
+const APPS = {
+  searchEventsChart: "src/apps/search-events-chart/index.html",
+};
+
+function main() {
+  // Ensure dist directory exists
+  if (!existsSync(DIST_DIR)) {
+    mkdirSync(DIST_DIR, { recursive: true });
+  }
+
+  // Read bundled HTML files and generate exports
+  const exports: Record<string, string> = {};
+
+  for (const [exportName, fileName] of Object.entries(APPS)) {
+    const htmlPath = join(APPS_DIR, fileName);
+
+    if (!existsSync(htmlPath)) {
+      console.error(`Warning: ${htmlPath} not found. Skipping.`);
+      continue;
+    }
+
+    const htmlContent = readFileSync(htmlPath, "utf-8");
+    exports[exportName] = htmlContent;
+    console.log(`Bundled ${fileName} -> ${exportName}Html`);
+  }
+
+  // Generate JavaScript module
+  const jsContent = `// Auto-generated by bundle-apps.ts - do not edit manually
+${Object.entries(exports)
+  .map(
+    ([name, content]) =>
+      `export const ${name}Html = ${JSON.stringify(content)};`,
+  )
+  .join("\n")}
+
+// Re-export shared types and utilities
+export { inferChartType } from "./shared/chart-data.js";
+`;
+
+  writeFileSync(join(DIST_DIR, "index.js"), jsContent);
+  console.log("Generated dist/index.js");
+
+  // Generate TypeScript declarations
+  const dtsContent = `// Auto-generated by bundle-apps.ts - do not edit manually
+${Object.keys(exports)
+  .map((name) => `export declare const ${name}Html: string;`)
+  .join("\n")}
+
+// Re-export shared types
+export type { ChartData, ChartType } from "./shared/chart-data.js";
+export { inferChartType } from "./shared/chart-data.js";
+`;
+
+  writeFileSync(join(DIST_DIR, "index.d.ts"), dtsContent);
+  console.log("Generated dist/index.d.ts");
+}
+
+main();

packages/mcp-apps-ui/src/apps/search-events-chart/app.ts

@@ -0,0 +1,264 @@
+import { App } from "@modelcontextprotocol/ext-apps";
+import { Chart, registerables } from "chart.js";
+import { SENTRY_COLORS, CHART_DEFAULTS } from "../../shared/sentry-theme";
+import type { ChartData, ChartType } from "../../shared/chart-data";
+import { inferChartType } from "../../shared/chart-data";
+
+// Register all Chart.js components
+Chart.register(...registerables);
+
+// Apply global chart defaults
+Chart.defaults.font.family = CHART_DEFAULTS.font.family;
+Chart.defaults.font.size = CHART_DEFAULTS.font.size;
+Chart.defaults.color = CHART_DEFAULTS.colors.text;
+
+const app = new App({ name: "Sentry Search Events Chart", version: "1.0.0" });
+
+let currentChart: Chart | null = null;
+
+/**
+ * Parse chart data from tool result content
+ */
+function parseChartData(result: {
+  content?: Array<{
+    type: string;
+    resource?: { mimeType?: string; text?: string };
+  }>;
+}): ChartData | null {
+  // Find the JSON resource containing chart data
+  const chartResource = result.content?.find(
+    (c) =>
+      c.type === "resource" &&
+      c.resource?.mimeType === "application/json;chart",
+  );
+
+  if (!chartResource?.resource?.text) {
+    return null;
+  }
+
+  try {
+    return JSON.parse(chartResource.resource.text) as ChartData;
+  } catch {
+    console.error("Failed to parse chart data");
+    return null;
+  }
+}
+
+/**
+ * Format a number for display (with thousands separators)
+ */
+function formatNumber(value: unknown): string {
+  if (typeof value === "number") {
+    return value.toLocaleString();
+  }
+  return String(value);
+}
+
+/**
+ * Render a single number display
+ */
+function renderNumberDisplay(data: ChartData): void {
+  const content = document.getElementById("content");
+  if (!content) return;
+
+  const value = data.data[0]?.[data.values[0]];
+
+  content.innerHTML = `
+    <div class="number-display">
+      <div class="number-value">${formatNumber(value)}</div>
+      <div class="number-label">${data.values[0]}</div>
+    </div>
+  `;
+}
+
+/**
+ * Render a data table
+ */
+function renderTable(data: ChartData): void {
+  const content = document.getElementById("content");
+  if (!content) return;
+
+  const allColumns = [...data.labels, ...data.values];
+
+  let tableHtml = `
+    <div class="table-container">
+      <table>
+        <thead>
+          <tr>
+            ${allColumns.map((col) => `<th>${col}</th>`).join("")}
+          </tr>
+        </thead>
+        <tbody>
+  `;
+
+  for (const row of data.data) {
+    tableHtml += "<tr>";
+    for (const col of allColumns) {
+      const value = row[col];
+      tableHtml += `<td>${formatNumber(value)}</td>`;
+    }
+    tableHtml += "</tr>";
+  }
+
+  tableHtml += `
+        </tbody>
+      </table>
+    </div>
+  `;
+
+  content.innerHTML = tableHtml;
+}
+
+/**
+ * Render a Chart.js chart
+ */
+function renderChart(data: ChartData, chartType: ChartType): void {
+  const content = document.getElementById("content");
+  if (!content) return;
+
+  // Clean up existing chart
+  if (currentChart) {
+    currentChart.destroy();
+    currentChart = null;
+  }
+
+  content.innerHTML = `
+    <div class="chart-container">
+      <canvas id="chart"></canvas>
+    </div>
+  `;
+
+  const canvas = document.getElementById("chart") as HTMLCanvasElement;
+  if (!canvas) return;
+
+  const ctx = canvas.getContext("2d");
+  if (!ctx) return;
+
+  // Extract labels (x-axis values)
+  const labelField = data.labels[0] || "label";
+  const labels = data.data.map((d) => String(d[labelField] || "Unknown"));
+
+  // Extract values (y-axis datasets)
+  const datasets = data.values.map((valueField, index) => ({
+    label: valueField,
+    data: data.data.map((d) => {
+      const val = d[valueField];
+      return typeof val === "number" ? val : 0;
+    }),
+    backgroundColor:
+      chartType === "pie"
+        ? data.data.map(
+            (_, i) => SENTRY_COLORS.series[i % SENTRY_COLORS.series.length],
+          )
+        : SENTRY_COLORS.series[index % SENTRY_COLORS.series.length],
+    borderColor:
+      chartType === "line"
+        ? SENTRY_COLORS.series[index % SENTRY_COLORS.series.length]
+        : undefined,
+    borderWidth: chartType === "line" ? 2 : 0,
+    fill: chartType === "line" ? false : undefined,
+    tension: chartType === "line" ? 0.3 : undefined,
+  }));
+
+  // Map our chart types to Chart.js types (number/table are handled separately)
+  const chartJsTypeMap: Record<string, "bar" | "pie" | "line"> = {
+    pie: "pie",
+    line: "line",
+  };
+  const chartJsType = chartJsTypeMap[chartType] ?? "bar";
+
+  currentChart = new Chart(ctx, {
+    type: chartJsType,
+    data: {
+      labels,
+      datasets,
+    },
+    options: {
+      responsive: true,
+      maintainAspectRatio: false,
+      plugins: {
+        legend: {
+          display: datasets.length > 1 || chartType === "pie",
+          position: chartType === "pie" ? "right" : "top",
+        },
+        title: {
+          display: false,
+        },
+      },
+      scales:
+        chartType === "pie"
+          ? {}
+          : {
+              x: {
+                grid: {
+                  color: CHART_DEFAULTS.colors.gridLines,
+                },
+              },
+              y: {
+                beginAtZero: true,
+                grid: {
+                  color: CHART_DEFAULTS.colors.gridLines,
+                },
+              },
+            },
+    },
+  });
+}
+
+/**
+ * Main render function
+ */
+function render(data: ChartData): void {
+  const title = document.getElementById("title");
+  const subtitle = document.getElementById("subtitle");
+
+  if (title) {
+    title.textContent = data.query;
+  }
+
+  if (subtitle) {
+    subtitle.textContent = `${data.data.length} result${data.data.length === 1 ? "" : "s"}`;
+  }
+
+  // Determine chart type (use provided or infer)
+  const chartType: ChartType =
+    data.chartType || inferChartType(data.data, data.labels, data.values);
+
+  switch (chartType) {
+    case "number":
+      renderNumberDisplay(data);
+      break;
+    case "table":
+      renderTable(data);
+      break;
+    default:
+      renderChart(data, chartType);
+  }
+}
+
+/**
+ * Show error message
+ */
+function showError(message: string): void {
+  const content = document.getElementById("content");
+  if (content) {
+    content.innerHTML = `<div class="error">${message}</div>`;
+  }
+}
+
+// Handle tool results from the server
+app.ontoolresult = (result) => {
+  const chartData = parseChartData(result);
+
+  if (chartData) {
+    render(chartData);
+  } else {
+    showError("No chart data available in the tool response.");
+  }
+};
+
+// Connect to the host
+app.connect().catch((error) => {
+  console.error("Failed to connect to MCP host:", error);
+  showError("Failed to connect to visualization host.");
+});