diff --git a/README.md b/README.md
index 6962d553..28a3f9c8 100644
--- a/README.md
+++ b/README.md
@@ -41,7 +41,7 @@ Codex Panel supports Codex App Server workflows that fit a persistent panel in O
 - Manage thread history from the panel or slash commands: clear (`/clear`), resume (`/resume`), rename, auto-name, fork (`/fork`), roll back (`/rollback`), compact (`/compact`), and archive (`/archive`) Codex threads.
 - Compose with Codex-aware completions for slash commands, enabled skills (`$skill-name`), recent threads, models, and supported reasoning efforts; use `/help` to show available slash commands.
 - Reference another non-archived thread without switching away from the current one (`/refer`).
-- Control subsequent turns from the toolbar or slash commands: Plan mode (`/plan`), fast mode (`/fast`), approval auto-review (`/auto-review`), model (`/model`), and reasoning effort (`/effort`).
+- Control subsequent turns from the toolbar or slash commands: Plan mode (`/plan`), fast mode (`/fast`), approval auto-review (`/auto-review`), model (`/model`), and reasoning effort (`/reasoning`).
 - Follow a running turn as Codex streams assistant messages, reasoning, commands, tool calls, hooks, file changes, plan updates, and agent activity.
 - Respond to Codex questions, command approvals, file approvals, MCP requests, and permission requests; send steering messages; or interrupt when the composer is empty.
 - Inspect context usage, usage limits, connection diagnostics, MCP servers, enabled skills, effective Codex config, and discovered hooks from the toolbar, settings, or `/status`, `/doctor`, and `/mcp`.
diff --git a/src/features/chat/composer/slash-commands.ts b/src/features/chat/composer/slash-commands.ts
index 862f0534..8ac218e1 100644
--- a/src/features/chat/composer/slash-commands.ts
+++ b/src/features/chat/composer/slash-commands.ts
@@ -97,11 +97,11 @@ export const SLASH_COMMANDS = [
     detail: "Show or set the model for subsequent turns.",
   },
   {
-    command: "/effort",
-    usage: "/effort [effort|default]",
+    command: "/reasoning",
+    usage: "/reasoning [level|default]",
     argsKind: "showOrSet",
     surface: "threadSetting",
-    detail: "Show or set reasoning effort for subsequent turns.",
+    detail: "Show or set reasoning level for subsequent turns.",
   },
   {
     command: "/help",
diff --git a/src/features/chat/composer/suggestions.ts b/src/features/chat/composer/suggestions.ts
index 2029f2fb..a47aae93 100644
--- a/src/features/chat/composer/suggestions.ts
+++ b/src/features/chat/composer/suggestions.ts
@@ -318,7 +318,7 @@ export function activeReasoningEffortSuggestions(
   models: readonly Model[],
   currentModel: string | null,
 ): ComposerSuggestion[] | null {
-  const completion = activeCommandArgumentCompletionQuery(beforeCursor, /^\/effort\s+([^\n]{0,120})$/);
+  const completion = activeCommandArgumentCompletionQuery(beforeCursor, /^\/reasoning\s+([^\n]{0,120})$/);
   if (!completion) return null;
 
   const { query, start } = completion;
diff --git a/src/features/chat/slash-commands.ts b/src/features/chat/slash-commands.ts
index d7f99610..5117d98e 100644
--- a/src/features/chat/slash-commands.ts
+++ b/src/features/chat/slash-commands.ts
@@ -190,7 +190,7 @@ export async function executeSlashCommand(
     return;
   }
 
-  if (command === "effort") {
+  if (command === "reasoning") {
     const requested = parseReasoningEffortOverride(args);
     if (requested !== undefined) {
       const applied = await context.setRequestedReasoningEffort(requested);
@@ -199,7 +199,7 @@ export async function executeSlashCommand(
       return;
     }
     if (args) {
-      context.addSystemMessage(`Unsupported effort: ${args}. Usage: ${slashCommandDefinition(command).usage}`);
+      context.addSystemMessage(`Unsupported reasoning level: ${args}. Usage: ${slashCommandDefinition(command).usage}`);
       return;
     }
     context.addStructuredSystemMessage("Reasoning effort", detailsFromLines(context.effortStatusLines()));
diff --git a/src/runtime/settings.ts b/src/runtime/settings.ts
index c703f01d..d92c322f 100644
--- a/src/runtime/settings.ts
+++ b/src/runtime/settings.ts
@@ -22,7 +22,9 @@ export function modelOverrideMessage(model: string | null): string {
 }
 
 export function reasoningEffortOverrideMessage(effort: ReasoningEffort | null): string {
-  return effort === null ? "Effort reset to default for subsequent turns." : `Effort set to ${effort} for subsequent turns.`;
+  return effort === null
+    ? "Reasoning effort reset to default for subsequent turns."
+    : `Reasoning effort set to ${effort} for subsequent turns.`;
 }
 
 export function compactModelLabel(model: string | null): string {
diff --git a/tests/features/chat/composer/composer-suggestions.test.ts b/tests/features/chat/composer/composer-suggestions.test.ts
index b145c135..242a2c5d 100644
--- a/tests/features/chat/composer/composer-suggestions.test.ts
+++ b/tests/features/chat/composer/composer-suggestions.test.ts
@@ -140,7 +140,7 @@ describe("composer suggestions", () => {
     expect(parseSlashCommand("/plan")).toEqual({ command: "plan", args: "" });
     expect(parseSlashCommand("/plan OK、実装してください")).toEqual({ command: "plan", args: "OK、実装してください" });
     expect(parseSlashCommand("/model gpt-5.5")).toEqual({ command: "model", args: "gpt-5.5" });
-    expect(parseSlashCommand("/effort high")).toEqual({ command: "effort", args: "high" });
+    expect(parseSlashCommand("/reasoning high")).toEqual({ command: "reasoning", args: "high" });
     expect(parseSlashCommand("/new")).toBeNull();
     expect(parseSlashCommand("/unknown")).toBeNull();
   });
@@ -223,7 +223,7 @@ describe("composer suggestions", () => {
   it("uses one active suggestion family at a time", () => {
     expect(activeComposerSuggestions("[[bet", notes, [])[0]?.replacement).toBe("[[Beta Note]]");
     expect(activeComposerSuggestions("/pla", notes, [])[0]?.replacement).toBe("/plan");
-    expect(activeComposerSuggestions("/eff", notes, [])[0]?.replacement).toBe("/effort");
+    expect(activeComposerSuggestions("/rea", notes, [])[0]?.replacement).toBe("/reasoning");
     expect(activeComposerSuggestions("/sta", notes, [])[0]?.replacement).toBe("/status");
     expect(activeComposerSuggestions("/doc", notes, [])[0]?.replacement).toBe("/doctor");
     expect(activeComposerSuggestions("/status", notes, [])).toEqual([]);
@@ -237,7 +237,7 @@ describe("composer suggestions", () => {
     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([]);
+    expect(activeComposerSuggestions("please\n/reasoning h", notes, [], [], models, "gpt-5.5")).toEqual([]);
   });
 
   it("suggests recent threads for /resume, /refer, and /archive arguments", () => {
@@ -314,21 +314,21 @@ describe("composer suggestions", () => {
     expect(activeComposerSuggestions("/model gpt-5.5 ", notes, [], [], models)).toEqual([]);
   });
 
-  it("suggests reasoning effort arguments for /effort", () => {
+  it("suggests reasoning effort arguments for /reasoning", () => {
     const models = [model("gpt-5.5", ["low", "medium", "high"]), model("gpt-5.4-mini", ["minimal", "low", "medium"])];
 
-    expect(activeComposerSuggestions("/effort h", notes, [], [], models, "gpt-5.5")[0]).toMatchObject({
+    expect(activeComposerSuggestions("/reasoning h", notes, [], [], models, "gpt-5.5")[0]).toMatchObject({
       display: "high",
       detail: "Supported by gpt-5.5",
       replacement: "high",
       appendSpaceOnInsert: true,
     });
     expect(
-      activeComposerSuggestions("/effort ", notes, [], [], models, "gpt-5.4-mini").map((suggestion) => suggestion.replacement),
+      activeComposerSuggestions("/reasoning ", notes, [], [], models, "gpt-5.4-mini").map((suggestion) => suggestion.replacement),
     ).toEqual(["default", "minimal", "low", "medium"]);
-    expect(activeComposerSuggestions("/effort x", notes, [], [], models, "gpt-5.4-mini")).toEqual([]);
-    expect(activeComposerSuggestions("/effort high", notes, [], [], models, "gpt-5.5")).toEqual([]);
-    expect(activeComposerSuggestions("/effort high ", notes, [], [], models, "gpt-5.5")).toEqual([]);
+    expect(activeComposerSuggestions("/reasoning x", notes, [], [], models, "gpt-5.4-mini")).toEqual([]);
+    expect(activeComposerSuggestions("/reasoning high", notes, [], [], models, "gpt-5.5")).toEqual([]);
+    expect(activeComposerSuggestions("/reasoning high ", notes, [], [], models, "gpt-5.5")).toEqual([]);
   });
 
   it("adds a trailing space for slash command and skill insertions only", () => {
diff --git a/tests/features/chat/composer/slash-commands.test.ts b/tests/features/chat/composer/slash-commands.test.ts
index ee7f39d5..73fd8bad 100644
--- a/tests/features/chat/composer/slash-commands.test.ts
+++ b/tests/features/chat/composer/slash-commands.test.ts
@@ -426,10 +426,10 @@ describe("slash commands", () => {
   it("rejects unsupported reasoning effort with usage", async () => {
     const ctx = context();
 
-    await executeSlashCommand("effort", "extreme", ctx);
+    await executeSlashCommand("reasoning", "extreme", ctx);
 
     expect(ctx.setRequestedReasoningEffort).not.toHaveBeenCalled();
-    expect(ctx.addSystemMessage).toHaveBeenCalledWith("Unsupported effort: extreme. Usage: /effort [effort|default]");
+    expect(ctx.addSystemMessage).toHaveBeenCalledWith("Unsupported reasoning level: extreme. Usage: /reasoning [level|default]");
   });
 
   it("does not announce model or effort changes when applying them fails", async () => {
@@ -439,7 +439,7 @@ describe("slash commands", () => {
     });
 
     await executeSlashCommand("model", "gpt-5.5", ctx);
-    await executeSlashCommand("effort", "high", ctx);
+    await executeSlashCommand("reasoning", "high", ctx);
 
     expect(ctx.setRequestedModel).toHaveBeenCalledWith("gpt-5.5");
     expect(ctx.setRequestedReasoningEffort).toHaveBeenCalledWith("high");
diff --git a/tests/runtime/runtime-settings.test.ts b/tests/runtime/runtime-settings.test.ts
index bd03b8a9..7f249f41 100644
--- a/tests/runtime/runtime-settings.test.ts
+++ b/tests/runtime/runtime-settings.test.ts
@@ -88,8 +88,8 @@ describe("runtime settings", () => {
   it("formats runtime override messages", () => {
     expect(modelOverrideMessage("gpt-5.5")).toBe("Model set to gpt-5.5 for subsequent turns.");
     expect(modelOverrideMessage(null)).toBe("Model reset to default for subsequent turns.");
-    expect(reasoningEffortOverrideMessage("low")).toBe("Effort set to low for subsequent turns.");
-    expect(reasoningEffortOverrideMessage(null)).toBe("Effort reset to default for subsequent turns.");
+    expect(reasoningEffortOverrideMessage("low")).toBe("Reasoning effort set to low for subsequent turns.");
+    expect(reasoningEffortOverrideMessage(null)).toBe("Reasoning effort reset to default for subsequent turns.");
   });
 
   it("formats compact runtime labels", () => {