diff --git a/apps/web/src/components/ComposerPromptEditorTiptap.tsx b/apps/web/src/components/ComposerPromptEditorTiptap.tsx
index 2a5fe2ba0588..c8866e7fc413 100644
--- a/apps/web/src/components/ComposerPromptEditorTiptap.tsx
+++ b/apps/web/src/components/ComposerPromptEditorTiptap.tsx
@@ -121,6 +121,11 @@ export interface ComposerPromptEditorProps {
   skills: ReadonlyArray<ServerProviderSkill>;
   disabled: boolean;
   placeholder: string;
+  ariaLabel?: string | undefined;
+  /** Identifies an editor with suggestions, even while its list is closed. */
+  suggestionListId?: string | undefined;
+  /** References the highlighted option only while its list is rendered. */
+  activeSuggestionId?: string | undefined;
   containerClassName?: string;
   className?: string;
   placeholderClassName?: string;
@@ -592,6 +597,9 @@ function ComposerPromptEditorTiptapInner(props: ComposerPromptEditorProps) {
     skills,
     disabled,
     placeholder,
+    ariaLabel,
+    suggestionListId,
+    activeSuggestionId,
     containerClassName,
     className,
     placeholderClassName,
@@ -752,9 +760,25 @@ function ComposerPromptEditorTiptapInner(props: ComposerPromptEditorProps) {
       ),
       "data-testid": "composer-editor",
       "data-composer-rich-text": richText ? "true" : "false",
+      role: "textbox",
+      "aria-multiline": "true",
+      ...(ariaLabel ? { "aria-label": ariaLabel } : {}),
+      ...(disabled ? { "aria-readonly": "true" } : {}),
+      ...(!disabled && suggestionListId
+        ? {
+            "aria-autocomplete": "list",
+            "aria-haspopup": "listbox",
+            ...(activeSuggestionId
+              ? {
+                  "aria-controls": suggestionListId,
+                  "aria-activedescendant": activeSuggestionId,
+                }
+              : {}),
+          }
+        : {}),
       "aria-placeholder": placeholder,
     }),
-    [className, placeholder, richText],
+    [activeSuggestionId, ariaLabel, className, disabled, placeholder, richText, suggestionListId],
   );
 
   const editor = useEditor(
diff --git a/apps/web/src/components/chat/ChatComposer.tsx b/apps/web/src/components/chat/ChatComposer.tsx
index d168c6db4e5f..f0383dbaf17b 100644
--- a/apps/web/src/components/chat/ChatComposer.tsx
+++ b/apps/web/src/components/chat/ChatComposer.tsx
@@ -58,6 +58,7 @@ import {
   type ReactNode,
   useCallback,
   useEffect,
+  useId,
   useImperativeHandle,
   useLayoutEffect,
   useMemo,
@@ -245,7 +246,11 @@ import { useEnvironmentQuery } from "~/state/query";
 import { useDebouncedValue } from "~/state/queries";
 import { ProviderModelPicker } from "./ProviderModelPicker";
 import { resolveModelPickerSelectedModel } from "./ModelPickerContent";
-import { type ComposerCommandItem, ComposerCommandMenu } from "./ComposerCommandMenu";
+import {
+  type ComposerCommandItem,
+  ComposerCommandMenu,
+  composerSuggestionOptionId,
+} from "./ComposerCommandMenu";
 import { ComposerPendingApprovalActions } from "./ComposerPendingApprovalActions";
 import { CompactComposerControlsMenu } from "./CompactComposerControlsMenu";
 import { ComposerImageThumbnail } from "./ComposerImageThumbnail";
@@ -2108,6 +2113,8 @@ export const ChatComposer = memo(function ChatComposer(props: ChatComposerProps)
     resetTrigger: resetComposerTrigger,
   } = useComposerTriggerState(() => detectComposerTrigger(prompt, prompt.length));
   const [composerHighlightedItemId, setComposerHighlightedItemId] = useState<string | null>(null);
+  const composerSuggestionId = useId();
+  const composerSuggestionListId = `${composerSuggestionId}-${encodeURIComponent(draftId ?? activeThreadId ?? "new")}-suggestions`;
   // Active ArrowUp recall. Cleared on edit and on thread switch.
   const promptHistoryPositionRef = useRef<ComposerPromptHistoryPosition | null>(null);
   const [composerHighlightedSearchKey, setComposerHighlightedSearchKey] = useState<string | null>(
@@ -2502,7 +2509,7 @@ export const ChatComposer = memo(function ChatComposer(props: ChatComposerProps)
 
   const composerMenuOpen = Boolean(composerTrigger);
   const composerMenuSearchKey = composerTrigger
-    ? `${composerTrigger.kind}:${composerTrigger.query.trim().toLowerCase()}`
+    ? `${composerSuggestionListId}:${composerTrigger.kind}:${composerTrigger.query.trim().toLowerCase()}`
     : null;
   const activeComposerMenuItem = useMemo(() => {
     const activeItemId = resolveComposerMenuActiveItemId({
@@ -2529,6 +2536,8 @@ export const ChatComposer = memo(function ChatComposer(props: ChatComposerProps)
   );
 
   const isComposerApprovalState = activePendingApproval !== null;
+  const composerSuggestionsVisible = composerMenuOpen && !isComposerApprovalState;
+  const composerSuggestionListVisible = composerSuggestionsVisible && composerMenuItems.length > 0;
   const activePendingUserInput = pendingUserInputs[0] ?? null;
   const isChoiceOnlyPendingQuestion =
     activePendingProgress?.activeQuestion?.allowCustomAnswer === false;
@@ -3176,6 +3185,7 @@ export const ChatComposer = memo(function ChatComposer(props: ChatComposerProps)
   // ------------------------------------------------------------------
   useEffect(() => {
     setComposerHighlightedItemId(null);
+    setComposerHighlightedSearchKey(null);
     setComposerSubmissionError(null);
     setProviderInputSubmissionError(null);
     setComposerCursor(collapseExpandedComposerCursor(promptRef.current, promptRef.current.length));
@@ -6454,9 +6464,19 @@ export const ChatComposer = memo(function ChatComposer(props: ChatComposerProps)
                 </ComposerCommandMenuLayer>
               )}
 
-              {composerMenuOpen && !isComposerApprovalState && (
+              <div role="status" aria-atomic="true" className="sr-only">
+                {composerSuggestionsVisible && composerMenuItems.length === 0
+                  ? isComposerMenuLoading
+                    ? composerTriggerKind === "pull-request"
+                      ? "Finding pull request..."
+                      : "Searching workspace files..."
+                    : composerMenuEmptyState
+                  : ""}
+              </div>
+              {composerSuggestionsVisible && (
                 <ComposerCommandMenuLayer anchor={composerMenuAnchor}>
                   <ComposerCommandMenu
+                    listId={composerSuggestionListId}
                     items={composerMenuItems}
                     resolvedTheme={resolvedTheme}
                     isLoading={isComposerMenuLoading}
@@ -6845,6 +6865,16 @@ export const ChatComposer = memo(function ChatComposer(props: ChatComposerProps)
                 ) : null}
                 <ComposerContextActionsContext value={composerContextActions}>
                   <ComposerPromptEditor
+                    ariaLabel="Message"
+                    suggestionListId={composerSuggestionListId}
+                    activeSuggestionId={
+                      composerSuggestionListVisible && activeComposerMenuItem
+                        ? composerSuggestionOptionId(
+                            composerSuggestionListId,
+                            activeComposerMenuItem.id,
+                          )
+                        : undefined
+                    }
                     editorRef={composerEditorRef}
                     richTextEnabled={settings.composerRichTextEnabled}
                     value={
diff --git a/apps/web/src/components/chat/ComposerCommandMenu.test.tsx b/apps/web/src/components/chat/ComposerCommandMenu.test.tsx
index 7a59d9054631..d26510ce0aef 100644
--- a/apps/web/src/components/chat/ComposerCommandMenu.test.tsx
+++ b/apps/web/src/components/chat/ComposerCommandMenu.test.tsx
@@ -2,12 +2,37 @@ import { renderToStaticMarkup } from "react-dom/server";
 import { ProviderDriverKind } from "@t3tools/contracts";
 import { describe, expect, it } from "vite-plus/test";
 
-import { ComposerCommandMenu } from "./ComposerCommandMenu";
+import { ComposerCommandMenu, composerSuggestionOptionId } from "./ComposerCommandMenu";
+
+describe("composerSuggestionOptionId", () => {
+  it("keeps whitespace, escape-like paths, and malformed UTF-16 distinct", () => {
+    const paths = [
+      "docs/my file.md",
+      "docs/my_file.md",
+      "docs/my%20file.md",
+      "docs/my\tfile.md",
+      "docs/\ud800.md",
+      "docs/\ud801.md",
+      "docs/\udc00.md",
+      "docs/\ufffd.md",
+      "docs/\\ud800.md",
+      "docs/\ud83d\ude80.md",
+    ];
+    const ids = paths.map((path) => composerSuggestionOptionId("suggestions", `path:file:${path}`));
+
+    expect(new Set(ids).size).toBe(paths.length);
+    for (const id of ids) expect(id).not.toMatch(/\s|[\ud800-\udfff]/u);
+    expect(composerSuggestionOptionId("other-composer", paths[0]!)).not.toBe(
+      composerSuggestionOptionId("suggestions", paths[0]!),
+    );
+  });
+});
 
 describe("ComposerCommandMenu", () => {
   it("renders slash commands with their descriptions", () => {
     const markup = renderToStaticMarkup(
       <ComposerCommandMenu
+        listId="test-suggestions"
         items={[
           {
             id: "slash:model",
@@ -33,6 +58,7 @@ describe("ComposerCommandMenu", () => {
   it("shows the app source for an app skill", () => {
     const markup = renderToStaticMarkup(
       <ComposerCommandMenu
+        listId="test-suggestions"
         items={[
           {
             id: "skill:codex:browser",
@@ -67,6 +93,7 @@ describe("ComposerCommandMenu", () => {
   it("shows the repo source for a slash skill", () => {
     const markup = renderToStaticMarkup(
       <ComposerCommandMenu
+        listId="test-suggestions"
         items={[
           {
             id: "skill:codex:ask-matt",
diff --git a/apps/web/src/components/chat/ComposerCommandMenu.tsx b/apps/web/src/components/chat/ComposerCommandMenu.tsx
index 4f0cabf8b4b4..86e40534a9e2 100644
--- a/apps/web/src/components/chat/ComposerCommandMenu.tsx
+++ b/apps/web/src/components/chat/ComposerCommandMenu.tsx
@@ -69,6 +69,7 @@ export type ComposerCommandItem =
     };
 
 export const ComposerCommandMenu = memo(function ComposerCommandMenu(props: {
+  listId: string;
   items: ComposerCommandItem[];
   resolvedTheme: "light" | "dark";
   isLoading: boolean;
@@ -104,11 +105,16 @@ export const ComposerCommandMenu = memo(function ComposerCommandMenu(props: {
         data-composer-command-drawer="true"
       >
         {props.items.length > 0 ? (
-          <CommandList className="max-h-72 min-h-0 scroll-pb-6">
+          <CommandList
+            id={props.listId}
+            aria-label={props.triggerKind ? LISTBOX_LABEL_BY_TRIGGER[props.triggerKind] : undefined}
+            className="max-h-72 min-h-0 scroll-pb-6"
+          >
             <CommandGroup>
               {props.items.map((item) => (
                 <ComposerCommandMenuItem
                   key={item.id}
+                  optionId={composerSuggestionOptionId(props.listId, item.id)}
                   item={item}
                   triggerKind={props.triggerKind}
                   resolvedTheme={props.resolvedTheme}
@@ -143,6 +149,7 @@ export const ComposerCommandMenu = memo(function ComposerCommandMenu(props: {
 });
 
 const ComposerCommandMenuItem = memo(function ComposerCommandMenuItem(props: {
+  optionId: string;
   item: ComposerCommandItem;
   triggerKind: ComposerTriggerKind | null;
   resolvedTheme: "light" | "dark";
@@ -159,6 +166,8 @@ const ComposerCommandMenuItem = memo(function ComposerCommandMenuItem(props: {
 
   return (
     <CommandItem
+      render={<div id={props.optionId} />}
+      aria-selected={props.isActive}
       value={props.item.id}
       data-composer-item-id={props.item.id}
       active={props.isActive}
@@ -211,6 +220,18 @@ const ComposerCommandMenuItem = memo(function ComposerCommandMenuItem(props: {
   );
 });
 
+export function composerSuggestionOptionId(listId: string, itemId: string): string {
+  // JSON escapes lone UTF-16 surrogates before URI encoding without losing identity.
+  return `${listId}-${encodeURIComponent(JSON.stringify(itemId))}`;
+}
+
+const LISTBOX_LABEL_BY_TRIGGER: Record<ComposerTriggerKind, string> = {
+  path: "Files and folders",
+  "pull-request": "Pull requests",
+  "slash-command": "Commands",
+  skill: "Skills",
+};
+
 const SKILL_SOURCE_ICON_BY_KIND: Record<ProviderSkillSourceKind, LucideIcon> = {
   app: BlocksIcon,
   repo: FolderIcon,
diff --git a/apps/web/src/components/chat/composerMenuHighlight.test.ts b/apps/web/src/components/chat/composerMenuHighlight.test.ts
index 549ad6bb09e8..74768d906878 100644
--- a/apps/web/src/components/chat/composerMenuHighlight.test.ts
+++ b/apps/web/src/components/chat/composerMenuHighlight.test.ts
@@ -48,4 +48,21 @@ describe("resolveComposerMenuActiveItemId", () => {
       }),
     ).toBe("top");
   });
+
+  it("clears the active result while async results are empty and resolves against restored results", () => {
+    const search = {
+      highlightedItemId: "second",
+      currentSearchKey: "path:src",
+      highlightedSearchKey: "path:src",
+    };
+    const cleared = resolveComposerMenuActiveItemId({ ...search, items: [] });
+    expect(cleared).toBeNull();
+    expect(
+      resolveComposerMenuActiveItemId({
+        ...search,
+        highlightedItemId: cleared,
+        items: [{ id: "new-result" }, { id: "second" }],
+      }),
+    ).toBe("new-result");
+  });
 });
diff --git a/apps/web/src/components/settings/SettingsFontPreviews.tsx b/apps/web/src/components/settings/SettingsFontPreviews.tsx
index 6f392598b9e7..4715583e4005 100644
--- a/apps/web/src/components/settings/SettingsFontPreviews.tsx
+++ b/apps/web/src/components/settings/SettingsFontPreviews.tsx
@@ -39,6 +39,7 @@ export function PromptFontPreview() {
   return (
     <div className="mt-1 mb-2 rounded-lg border border-border bg-background px-3 py-2">
       <ComposerPromptEditor
+        ariaLabel="Prompt font preview"
         editorRef={editorRef}
         value={prompt}
         cursor={cursor}