diff --git a/src/ui/shared/canonical-key.ts b/src/ui/shared/canonical-key.ts
new file mode 100644
index 00000000..ca44d646
--- /dev/null
+++ b/src/ui/shared/canonical-key.ts
@@ -0,0 +1,27 @@
+function encodeNumber(value: number): string {
+    if (Number.isNaN(value)) return 'number:NaN';
+    if (value === Infinity) return 'number:Infinity';
+    if (value === -Infinity) return 'number:-Infinity';
+    if (Object.is(value, -0)) return 'number:-0';
+    return `number:${value}`;
+}
+
+export function canonicalRequestKey(value: unknown): string {
+    if (value === null) return 'null';
+    if (Array.isArray(value)) return `array:[${value.map(canonicalRequestKey).join(',')}]`;
+
+    switch (typeof value) {
+        case 'string': return `string:${JSON.stringify(value)}`;
+        case 'number': return encodeNumber(value);
+        case 'boolean': return `boolean:${value}`;
+        case 'undefined': return 'undefined';
+        case 'object': {
+            const object = value as Record<string, unknown>;
+            return `object:{${Object.keys(object).sort().map(
+                (key) => `${JSON.stringify(key)}:${canonicalRequestKey(object[key])}`
+            ).join(',')}}`;
+        }
+        default:
+            throw new TypeError(`Unsupported request-key value: ${typeof value}`);
+    }
+}
diff --git a/src/ui/shared/tool-bridge.ts b/src/ui/shared/tool-bridge.ts
index 0f43b6c9..d3d74237 100644
--- a/src/ui/shared/tool-bridge.ts
+++ b/src/ui/shared/tool-bridge.ts
@@ -1,5 +1,7 @@
 type ToolArgs = Record<string, unknown>;
 
+import { canonicalRequestKey } from './canonical-key.js';
+
 type ToolHelper = {
     callTool: (name: string, args: ToolArgs) => Promise<unknown> | unknown;
 };
@@ -100,6 +102,7 @@ export function createToolBridge(options: ToolBridgeOptions = {}) {
     const targetOrigin = normalizeTargetOrigin(options.targetOrigin ?? getDefaultTargetOrigin());
     const idPrefix = options.idPrefix ?? 'tool-bridge';
     let requestCounter = 0;
+    const inFlight = new Map<string, Promise<unknown>>();
 
     async function callViaFallback(name: string, args: ToolArgs): Promise<unknown> {
         if (!host.parent || !host.addEventListener || !host.removeEventListener) {
@@ -166,8 +169,7 @@ export function createToolBridge(options: ToolBridgeOptions = {}) {
         });
     }
 
-    async function callTool(name: string, args?: ToolArgs): Promise<unknown> {
-        const normalizedArgs = normalizeToolArgs(args);
+    async function callToolOnce(name: string, normalizedArgs: ToolArgs): Promise<unknown> {
         const helperCandidates = [host.openai, host.mcp].filter(
             (candidate): candidate is ToolHelper => Boolean(candidate?.callTool)
         );
@@ -190,6 +192,25 @@ export function createToolBridge(options: ToolBridgeOptions = {}) {
         }
     }
 
+    async function callTool(name: string, args?: ToolArgs): Promise<unknown> {
+        const normalizedArgs = normalizeToolArgs(args);
+        const key = `${name}:${canonicalRequestKey(normalizedArgs)}`;
+        const existing = inFlight.get(key);
+        if (existing) {
+            return existing;
+        }
+
+        const pending = callToolOnce(name, normalizedArgs);
+        inFlight.set(key, pending);
+        try {
+            return await pending;
+        } finally {
+            if (inFlight.get(key) === pending) {
+                inFlight.delete(key);
+            }
+        }
+    }
+
     return {
         callTool,
     };
diff --git a/src/ui/shared/ui-event-tracker.ts b/src/ui/shared/ui-event-tracker.ts
index 9ddde38b..4b5b2c26 100644
--- a/src/ui/shared/ui-event-tracker.ts
+++ b/src/ui/shared/ui-event-tracker.ts
@@ -1,5 +1,7 @@
 type UiEventParamValue = string | number | boolean | null;
 
+import { canonicalRequestKey } from './canonical-key.js';
+
 export type UiEventParams = Record<string, UiEventParamValue>;
 
 type ToolCaller = (name: string, args: Record<string, unknown>) => Promise<unknown>;
@@ -27,15 +29,36 @@ function normalizeUiEventParams(params: Record<string, unknown> | undefined): Ui
 
 export function createUiEventTracker(callTool: ToolCaller, options: UiEventTrackerOptions) {
     const baseParams = options.baseParams ?? {};
+    const recentEvents = new Map<string, number>();
+    const duplicateWindowMs = 250;
 
     return (event: string, params: Record<string, unknown> = {}): void => {
+        const normalizedParams = {
+            ...baseParams,
+            ...normalizeUiEventParams(params),
+        };
+        const key = canonicalRequestKey([event, normalizedParams]);
+        const now = Date.now();
+        const lastSeen = recentEvents.get(key);
+        if (lastSeen !== undefined && now - lastSeen < duplicateWindowMs) {
+            return;
+        }
+        recentEvents.set(key, now);
+        if (recentEvents.size > 100) {
+            for (const [candidate, timestamp] of recentEvents) {
+                if (now - timestamp >= duplicateWindowMs) recentEvents.delete(candidate);
+            }
+            while (recentEvents.size > 100) {
+                const oldest = recentEvents.keys().next().value;
+                if (oldest === undefined) break;
+                recentEvents.delete(oldest);
+            }
+        }
+
         void callTool('track_ui_event', {
             event,
             component: options.component,
-            params: {
-                ...baseParams,
-                ...normalizeUiEventParams(params),
-            },
+            params: normalizedParams,
         }).catch(() => {
             // UI analytics should never block UI interactions.
         });
diff --git a/test/test-ui-event-tracking.js b/test/test-ui-event-tracking.js
index 29b35dce..150c5d88 100644
--- a/test/test-ui-event-tracking.js
+++ b/test/test-ui-event-tracking.js
@@ -5,6 +5,8 @@ import assert from 'assert';
 
 import { server } from '../dist/server.js';
 import { buildTrackUiEventCapturePayload } from '../dist/handlers/history-handlers.js';
+import { createToolBridge } from '../dist/ui/shared/tool-bridge.js';
+import { createUiEventTracker } from '../dist/ui/shared/ui-event-tracker.js';
 
 function getRequestHandler(method) {
   const handlers = server._requestHandlers;
@@ -54,10 +56,108 @@ async function testTrackUiEventPayloadCollisionProtection() {
   console.log('✓ track_ui_event payload collision protection works');
 }
 
+async function testConcurrentWidgetCallsAreCoalesced() {
+  console.log('\n--- Test: identical concurrent widget calls are coalesced ---');
+  let calls = 0;
+  let release;
+  const gate = new Promise((resolve) => { release = resolve; });
+  const bridge = createToolBridge({
+    host: {
+      openai: {
+        callTool: async () => {
+          calls++;
+          await gate;
+          return { content: [{ type: 'text', text: 'ok' }] };
+        },
+      },
+    },
+  });
+
+  const first = bridge.callTool('read_file', { path: 'same.txt', options: { offset: 0 } });
+  const second = bridge.callTool('read_file', { options: { offset: 0 }, path: 'same.txt' });
+  release();
+  const [a, b] = await Promise.all([first, second]);
+
+  assert.strictEqual(calls, 1, 'equivalent in-flight requests should share one host call');
+  assert.deepStrictEqual(a, b);
+  console.log('✓ identical concurrent calls share one request');
+}
+
+async function testSequentialWidgetCallsRunAgain() {
+  console.log('\n--- Test: sequential widget calls are not suppressed ---');
+  let calls = 0;
+  const bridge = createToolBridge({
+    host: { openai: { callTool: async () => ({ call: ++calls }) } },
+  });
+
+  await bridge.callTool('get_config', {});
+  await bridge.callTool('get_config', {});
+  assert.strictEqual(calls, 2, 'request should run again after the prior call settles');
+  console.log('✓ sequential calls execute normally');
+}
+
+async function testCanonicalWidgetCallKeys() {
+  console.log('\n--- Test: canonical widget keys preserve distinct values ---');
+  let calls = 0;
+  let release;
+  const gate = new Promise((resolve) => { release = resolve; });
+  const bridge = createToolBridge({
+    host: { openai: { callTool: async () => { calls++; await gate; return {}; } } },
+  });
+
+  const reorderedA = bridge.callTool('read_file', { options: { offset: 0, length: 1 } });
+  const reorderedB = bridge.callTool('read_file', { options: { length: 1, offset: 0 } });
+  const nanCall = bridge.callTool('read_file', { value: Number.NaN });
+  const nullCall = bridge.callTool('read_file', { value: null });
+  release();
+  await Promise.all([reorderedA, reorderedB, nanCall, nullCall]);
+
+  assert.strictEqual(calls, 3, 'reordered keys coalesce, while NaN and null remain distinct');
+  console.log('✓ canonical keys coalesce only equivalent requests');
+}
+
+async function testDuplicateUiEventsAreSuppressed() {
+  console.log('\n--- Test: immediate duplicate UI events are suppressed ---');
+  const calls = [];
+  const track = createUiEventTracker(
+    async (name, args) => { calls.push({ name, args }); return {}; },
+    { component: 'test-widget' },
+  );
+
+  track('click', { target: 'refresh' });
+  track('click', { target: 'refresh' });
+  track('click', { target: 'other' });
+  await new Promise((resolve) => setTimeout(resolve, 0));
+
+  assert.strictEqual(calls.length, 2, 'duplicate should collapse while distinct event remains');
+  console.log('✓ duplicate event collapsed without suppressing distinct event');
+}
+
+async function testUiEventCacheStaysBounded() {
+  console.log('\n--- Test: UI event cache stays bounded ---');
+  const calls = [];
+  const track = createUiEventTracker(
+    async (_name, args) => { calls.push(args); return {}; },
+    { component: 'test-widget' },
+  );
+
+  for (let index = 0; index < 101; index++) track('click', { index });
+  track('click', { index: 0 });
+  await new Promise((resolve) => setTimeout(resolve, 0));
+
+  assert.strictEqual(calls.length, 102, 'oldest unique event should be evicted once the cache exceeds 100');
+  console.log('✓ unique-event bursts retain at most 100 dedupe keys');
+}
+
 export default async function runTests() {
   try {
     await testTrackUiEventCall();
     await testTrackUiEventPayloadCollisionProtection();
+    await testConcurrentWidgetCallsAreCoalesced();
+    await testSequentialWidgetCallsRunAgain();
+    await testCanonicalWidgetCallKeys();
+    await testDuplicateUiEventsAreSuppressed();
+    await testUiEventCacheStaysBounded();
     console.log('\n✅ UI event tracking tests passed!');
     return true;
   } catch (error) {