diff --git a/assets/js/autocomplete/__tests__/context.ts b/assets/js/autocomplete/__tests__/context.ts
index fabfab23..89e949eb 100644
--- a/assets/js/autocomplete/__tests__/context.ts
+++ b/assets/js/autocomplete/__tests__/context.ts
@@ -6,7 +6,7 @@ import { fireEvent } from '@testing-library/dom';
 import { assertNotNull } from '../../utils/assert';
 import { TextInputElement } from '../input';
 import store from '../../utils/store';
-import { GetTagSuggestionsResponse } from 'autocomplete/client';
+import { GetTagSuggestionsResponse, TagSuggestion } from 'autocomplete/client';
 
 /**
  * A reusable test environment for autocompletion tests. Note that it does no
@@ -44,27 +44,30 @@ export class TestContext {
       }
 
       const url = new URL(request.url);
-      if (url.searchParams.get('term')?.toLowerCase() !== 'mar') {
-        const suggestions: GetTagSuggestionsResponse = { suggestions: [] };
-        return JSON.stringify(suggestions);
-      }
+      const term = url.searchParams.get('term');
+
+      const termLower = assertNotNull(term).toLowerCase();
+
+      const fakeSuggestions: TagSuggestion[] = [
+        {
+          alias: 'marvelous',
+          canonical: 'beautiful',
+          images: 30,
+        },
+        {
+          canonical: 'mare',
+          images: 20,
+        },
+        {
+          canonical: 'market',
+          images: 10,
+        },
+      ];
 
       const suggestions: GetTagSuggestionsResponse = {
-        suggestions: [
-          {
-            alias: 'marvelous',
-            canonical: 'beautiful',
-            images: 30,
-          },
-          {
-            canonical: 'mare',
-            images: 20,
-          },
-          {
-            canonical: 'market',
-            images: 10,
-          },
-        ],
+        suggestions: fakeSuggestions.filter(suggestion =>
+          (suggestion.alias || suggestion.canonical).startsWith(termLower),
+        ),
       };
 
       return JSON.stringify(suggestions);
diff --git a/assets/js/autocomplete/__tests__/server-side-completions-aborting.spec.ts b/assets/js/autocomplete/__tests__/server-side-completions-aborting.spec.ts
deleted file mode 100644
index 4bf8617e..00000000
--- a/assets/js/autocomplete/__tests__/server-side-completions-aborting.spec.ts
+++ /dev/null
@@ -1,34 +0,0 @@
-import { init } from './context';
-
-it('ignores the autocompletion results if Escape was pressed', async () => {
-  const ctx = await init();
-
-  await Promise.all([ctx.setInput('mar'), ctx.keyDown('Escape')]);
-
-  // The input must be empty because the user typed `mar` and pressed `Escape` right after that
-  ctx.expectUi().toMatchInlineSnapshot(`
-    {
-      "input": "mar<>",
-      "suggestions": [],
-    }
-  `);
-
-  // First request for the local autocomplete index.
-  expect(fetch).toHaveBeenCalledTimes(1);
-
-  await ctx.setInput('mar');
-
-  ctx.expectUi().toMatchInlineSnapshot(`
-    {
-      "input": "mar<>",
-      "suggestions": [
-        "marvelous → beautiful  30",
-        "mare  20",
-        "market  10",
-      ],
-    }
-  `);
-
-  // Second request for the server-side suggestions.
-  expect(fetch).toHaveBeenCalledTimes(2);
-});
diff --git a/assets/js/autocomplete/__tests__/server-side-completions/debouncing.spec.ts b/assets/js/autocomplete/__tests__/server-side-completions/debouncing.spec.ts
new file mode 100644
index 00000000..f3bd94a4
--- /dev/null
+++ b/assets/js/autocomplete/__tests__/server-side-completions/debouncing.spec.ts
@@ -0,0 +1,71 @@
+import { init } from '../context';
+
+it('ignores the autocompletion results if Escape was pressed', async () => {
+  const ctx = await init();
+
+  // First request for the local autocomplete index was done
+  expect(fetch).toHaveBeenCalledTimes(1);
+
+  await Promise.all([ctx.setInput('mar'), ctx.keyDown('Escape')]);
+
+  // The input must be empty because the user typed `mar` and pressed `Escape` right after that
+  ctx.expectUi().toMatchInlineSnapshot(`
+    {
+      "input": "mar<>",
+      "suggestions": [],
+    }
+  `);
+
+  // No new requests must've been sent because the input was debounced early
+  expect(fetch).toHaveBeenCalledTimes(1);
+
+  await ctx.setInput('mar');
+
+  ctx.expectUi().toMatchInlineSnapshot(`
+    {
+      "input": "mar<>",
+      "suggestions": [
+        "marvelous → beautiful  30",
+        "mare  20",
+        "market  10",
+      ],
+    }
+  `);
+
+  // Second request for the server-side suggestions.
+  expect(fetch).toHaveBeenCalledTimes(2);
+
+  ctx.setInput('mare');
+
+  // After 300 milliseconds the debounce threshold is over, and the server-side
+  // completions request is issued.
+  vi.advanceTimersByTime(300);
+
+  await ctx.keyDown('Escape');
+
+  expect(fetch).toHaveBeenCalledTimes(3);
+
+  ctx.expectUi().toMatchInlineSnapshot(`
+    {
+      "input": "mare<>",
+      "suggestions": [],
+    }
+  `);
+
+  ctx.setInput('mare');
+
+  // Make sure that the user gets the results immediately without any debouncing (0 ms)
+  await vi.advanceTimersByTimeAsync(0);
+
+  ctx.expectUi().toMatchInlineSnapshot(`
+    {
+      "input": "mare<>",
+      "suggestions": [
+        "mare  20",
+      ],
+    }
+  `);
+
+  // The results must come from the cache, so no new fetch calls must have been made
+  expect(fetch).toHaveBeenCalledTimes(3);
+});
diff --git a/assets/js/autocomplete/__tests__/server-side-completions-smoke.spec.ts b/assets/js/autocomplete/__tests__/server-side-completions/smoke.spec.ts
similarity index 96%
rename from assets/js/autocomplete/__tests__/server-side-completions-smoke.spec.ts
rename to assets/js/autocomplete/__tests__/server-side-completions/smoke.spec.ts
index fcf53eb7..e487b281 100644
--- a/assets/js/autocomplete/__tests__/server-side-completions-smoke.spec.ts
+++ b/assets/js/autocomplete/__tests__/server-side-completions/smoke.spec.ts
@@ -1,4 +1,4 @@
-import { init } from './context';
+import { init } from '../context';
 
 it('requests server-side autocomplete if local autocomplete returns no results', async () => {
   const ctx = await init();