diff --git a/apps/web/src/components/chat/CompactComposerControlsMenu.browser.tsx b/apps/web/src/components/chat/CompactComposerControlsMenu.browser.tsx
index aa3550e007..eee6f885e9 100644
--- a/apps/web/src/components/chat/CompactComposerControlsMenu.browser.tsx
+++ b/apps/web/src/components/chat/CompactComposerControlsMenu.browser.tsx
@@ -220,7 +220,7 @@ describe("CompactComposerControlsMenu", () => {
     });
   });
 
-  it("shows prompt-controlled Ultrathink messaging with disabled effort controls", async () => {
+  it("shows prompt-controlled Ultrathink state with selectable effort controls", async () => {
     await using _ = await mountMenu({
       modelSelection: {
         provider: "claudeAgent",
@@ -235,8 +235,27 @@ describe("CompactComposerControlsMenu", () => {
     await vi.waitFor(() => {
       const text = document.body.textContent ?? "";
       expect(text).toContain("Effort");
-      expect(text).toContain("Remove Ultrathink from the prompt to change effort.");
-      expect(text).not.toContain("Fallback Effort");
+      expect(text).not.toContain("ultrathink");
+    });
+  });
+
+  it("warns when ultrathink appears in prompt body text", async () => {
+    await using _ = await mountMenu({
+      modelSelection: {
+        provider: "claudeAgent",
+        model: "claude-opus-4-6",
+        options: { effort: "high" },
+      },
+      prompt: "Ultrathink:\nplease ultrathink about this problem",
+    });
+
+    await page.getByLabelText("More composer controls").click();
+
+    await vi.waitFor(() => {
+      const text = document.body.textContent ?? "";
+      expect(text).toContain(
+        'Your prompt contains "ultrathink" in the text. Remove it to change effort.',
+      );
     });
   });
 });
diff --git a/apps/web/src/components/chat/TraitsPicker.browser.tsx b/apps/web/src/components/chat/TraitsPicker.browser.tsx
index 99d09fd634..9dea3651ea 100644
--- a/apps/web/src/components/chat/TraitsPicker.browser.tsx
+++ b/apps/web/src/components/chat/TraitsPicker.browser.tsx
@@ -296,7 +296,7 @@ describe("TraitsPicker (Claude)", () => {
     });
   });
 
-  it("shows prompt-controlled Ultrathink state with disabled effort controls", async () => {
+  it("shows prompt-controlled Ultrathink state with selectable effort controls", async () => {
     await using _ = await mountClaudePicker({
       model: "claude-opus-4-6",
       options: { effort: "high" },
@@ -312,8 +312,24 @@ describe("TraitsPicker (Claude)", () => {
     await vi.waitFor(() => {
       const text = document.body.textContent ?? "";
       expect(text).toContain("Effort");
-      expect(text).toContain("Remove Ultrathink from the prompt to change effort.");
-      expect(text).not.toContain("Fallback Effort");
+      expect(text).not.toContain("ultrathink");
+    });
+  });
+
+  it("warns when ultrathink appears in prompt body text", async () => {
+    await using _ = await mountClaudePicker({
+      model: "claude-opus-4-6",
+      options: { effort: "high" },
+      prompt: "Ultrathink:\nplease ultrathink about this problem",
+    });
+
+    await page.getByRole("button").click();
+
+    await vi.waitFor(() => {
+      const text = document.body.textContent ?? "";
+      expect(text).toContain(
+        'Your prompt contains "ultrathink" in the text. Remove it to change effort.',
+      );
     });
   });
 
diff --git a/apps/web/src/components/chat/TraitsPicker.tsx b/apps/web/src/components/chat/TraitsPicker.tsx
index a3b6cbb48f..061594ad53 100644
--- a/apps/web/src/components/chat/TraitsPicker.tsx
+++ b/apps/web/src/components/chat/TraitsPicker.tsx
@@ -120,6 +120,10 @@ function getSelectedTraits(
     caps.promptInjectedEffortLevels.length > 0 &&
     isClaudeUltrathinkPrompt(prompt);
 
+  // Check if "ultrathink" appears in the body text (not just our prefix)
+  const ultrathinkInBodyText =
+    ultrathinkPromptControlled && isClaudeUltrathinkPrompt(prompt.replace(/^Ultrathink:\s*/i, ""));
+
   return {
     caps,
     effort,
@@ -130,6 +134,7 @@ function getSelectedTraits(
     contextWindow,
     defaultContextWindow,
     ultrathinkPromptControlled,
+    ultrathinkInBodyText,
   };
 }
 
@@ -176,12 +181,12 @@ export const TraitsMenuContent = memo(function TraitsMenuContentImpl({
     contextWindow,
     defaultContextWindow,
     ultrathinkPromptControlled,
+    ultrathinkInBodyText,
   } = getSelectedTraits(provider, models, model, prompt, modelOptions, allowPromptInjectedEffort);
   const defaultEffort = getDefaultEffort(caps);
 
   const handleEffortChange = useCallback(
     (value: string) => {
-      if (ultrathinkPromptControlled) return;
       if (!value) return;
       const nextOption = effortLevels.find((option) => option.value === value);
       if (!nextOption) return;
@@ -193,6 +198,11 @@ export const TraitsMenuContent = memo(function TraitsMenuContentImpl({
         onPromptChange(nextPrompt);
         return;
       }
+      if (ultrathinkInBodyText) return;
+      if (ultrathinkPromptControlled) {
+        const stripped = prompt.replace(/^Ultrathink:\s*/i, "");
+        onPromptChange(stripped);
+      }
       const effortKey = provider === "codex" ? "reasoningEffort" : "effort";
       updateModelOptions(
         buildNextOptions(provider, modelOptions, { [effortKey]: nextOption.value }),
@@ -200,6 +210,7 @@ export const TraitsMenuContent = memo(function TraitsMenuContentImpl({
     },
     [
       ultrathinkPromptControlled,
+      ultrathinkInBodyText,
       modelOptions,
       onPromptChange,
       updateModelOptions,
@@ -220,17 +231,20 @@ export const TraitsMenuContent = memo(function TraitsMenuContentImpl({
         <>
           <MenuGroup>
             <div className="px-2 pt-1.5 pb-1 font-medium text-muted-foreground text-xs">Effort</div>
-            {ultrathinkPromptControlled ? (
+            {ultrathinkInBodyText ? (
               <div className="px-2 pb-1.5 text-muted-foreground/80 text-xs">
-                Remove Ultrathink from the prompt to change effort.
+                Your prompt contains &quot;ultrathink&quot; in the text. Remove it to change effort.
               </div>
             ) : null}
-            <MenuRadioGroup value={effort} onValueChange={handleEffortChange}>
+            <MenuRadioGroup
+              value={ultrathinkPromptControlled ? "ultrathink" : effort}
+              onValueChange={handleEffortChange}
+            >
               {effortLevels.map((option) => (
                 <MenuRadioItem
                   key={option.value}
                   value={option.value}
-                  disabled={ultrathinkPromptControlled}
+                  disabled={ultrathinkInBodyText}
                 >
                   {option.label}
                   {option.value === defaultEffort ? " (default)" : ""}