diff --git a/src/features/chat/composer/suggestions.ts b/src/features/chat/composer/suggestions.ts
index dd2d04a2..71cfb0a9 100644
--- a/src/features/chat/composer/suggestions.ts
+++ b/src/features/chat/composer/suggestions.ts
@@ -158,7 +158,7 @@ function compareWikiLinkSuggestionTiebreakers(a: NoteCandidateMatch, b: NoteCand
 }
 
 export function activeSlashCommandSuggestions(beforeCursor: string): ComposerSuggestion[] | null {
-  const match = /(?:^|\n)(\/[A-Za-z-]*)$/.exec(beforeCursor);
+  const match = /^(\/[A-Za-z-]*)$/.exec(beforeCursor);
   if (match?.index === undefined) return null;
 
   const rawQuery = match[1];
@@ -178,7 +178,7 @@ export function activeSlashCommandSuggestions(beforeCursor: string): ComposerSug
 }
 
 export function activeThreadCommandSuggestions(beforeCursor: string, threads: readonly Thread[]): ComposerSuggestion[] | null {
-  const match = /(?:^|\n)\/(?:resume|refer|archive)\s+([^\s\n]{0,120})$/.exec(beforeCursor);
+  const match = /^\/(?:resume|refer|archive)\s+([^\s\n]{0,120})$/.exec(beforeCursor);
   if (match?.index === undefined) return null;
 
   const rawQuery = match[1];
@@ -208,7 +208,7 @@ export function activeThreadCommandSuggestions(beforeCursor: string, threads: re
 }
 
 export function activeModelOverrideSuggestions(beforeCursor: string, models: readonly Model[]): ComposerSuggestion[] | null {
-  const match = /(?:^|\n)\/model\s+([^\n]{0,120})$/.exec(beforeCursor);
+  const match = /^\/model\s+([^\n]{0,120})$/.exec(beforeCursor);
   if (match?.index === undefined) return null;
 
   const rawQuery = match[1];
@@ -255,7 +255,7 @@ export function activeReasoningEffortSuggestions(
   models: readonly Model[],
   currentModel: string | null,
 ): ComposerSuggestion[] | null {
-  const match = /(?:^|\n)\/effort\s+([^\n]{0,120})$/.exec(beforeCursor);
+  const match = /^\/effort\s+([^\n]{0,120})$/.exec(beforeCursor);
   if (match?.index === undefined) return null;
 
   const rawQuery = match[1];
diff --git a/tests/features/chat/composer/composer-suggestions.test.ts b/tests/features/chat/composer/composer-suggestions.test.ts
index 681b5719..5e6bfe72 100644
--- a/tests/features/chat/composer/composer-suggestions.test.ts
+++ b/tests/features/chat/composer/composer-suggestions.test.ts
@@ -175,6 +175,16 @@ describe("composer suggestions", () => {
     expect(activeComposerSuggestions("/help", notes, [])).toEqual([]);
   });
 
+  it("limits slash command suggestions to the start of the composer", () => {
+    const threads = [thread({ id: "019abcde-0000-7000-8000-000000000001", name: "Codex Panel実装" })];
+    const models = [model("gpt-5.5", ["low", "medium", "high"])];
+
+    expect(activeComposerSuggestions("please\n/sta", notes, [])).toEqual([]);
+    expect(activeComposerSuggestions("please\n/resume codex", notes, [], threads)).toEqual([]);
+    expect(activeComposerSuggestions("please\n/model gpt", notes, [], [], models)).toEqual([]);
+    expect(activeComposerSuggestions("please\n/effort h", notes, [], [], models, "gpt-5.5")).toEqual([]);
+  });
+
   it("suggests recent threads for /resume, /refer, and /archive arguments", () => {
     const threads = [
       thread({ id: "019abcde-0000-7000-8000-000000000001", name: "Codex Panel実装" }),