diff --git a/e2e/ai-provider-dropdown.spec.ts b/e2e/ai-provider-dropdown.spec.ts
index ea2c00bb2..adacbdd2c 100644
--- a/e2e/ai-provider-dropdown.spec.ts
+++ b/e2e/ai-provider-dropdown.spec.ts
@@ -339,4 +339,116 @@ test.describe("Settings → AI provider dropdown UX (B2)", () => {
         .locator('button[type="submit"]'),
     ).toBeEnabled();
   });
+
+  // #1126 — the Reasoning select on the Local and OpenAI-compatible forms
+  // saves with the form, and at phone width it sits in the same column as
+  // the model field without pushing the page sideways.
+  test("reasoning setting saves from the Local and gateway forms at 390 px", async ({
+    page,
+  }) => {
+    await page.setViewportSize({ width: 390, height: 844 });
+    const patchBodies: Array<Record<string, unknown>> = [];
+    let providerState: Record<string, unknown> = {
+      provider: "LOCAL",
+      model: null,
+      baseUrl: "http://localhost:11434/v1",
+      responseTimeoutSeconds: null,
+      hasAnthropicKey: false,
+      anthropicKeyPreview: null,
+      hasLocalKey: false,
+      hasOpenaiKey: false,
+      openaiKeyPreview: null,
+      compatBaseUrl: "https://gateway.example.org/v1",
+      compatModel: "qwen3",
+      hasCompatKey: false,
+      localReasoningEffort: null,
+      compatReasoningEffort: null,
+    };
+    await page.route("**/api/insights/settings", (route) =>
+      route.fulfill({
+        status: 200,
+        contentType: "application/json",
+        body: JSON.stringify({
+          data: {
+            codexStatus: "disconnected",
+            codexConnectedAt: null,
+            hasAdminKey: false,
+            codexOauthConfigured: true,
+            privacyMode: "aggregated",
+            lastInsightAt: null,
+          },
+          error: null,
+        }),
+      }),
+    );
+    await page.route("**/api/user/ai-provider", async (route) => {
+      if (route.request().method() === "PATCH") {
+        const body = route.request().postDataJSON() as Record<string, unknown>;
+        patchBodies.push(body);
+        providerState = { ...providerState, ...body };
+      }
+      await route.fulfill({
+        status: 200,
+        contentType: "application/json",
+        body: JSON.stringify({ data: providerState, error: null }),
+      });
+    });
+    await page.route("**/api/insights/provider-chain", (route) =>
+      route.fulfill({
+        status: 200,
+        contentType: "application/json",
+        body: JSON.stringify({
+          data: {
+            activeProvider: "local",
+            cachedActiveProvider: null,
+            configuredChain: [
+              { providerType: "local", enabled: true, available: true },
+            ],
+          },
+          error: null,
+        }),
+      }),
+    );
+
+    const providerHydrated = page.waitForResponse("**/api/user/ai-provider");
+    await page.goto("/settings/ai?provider=local", {
+      waitUntil: "domcontentloaded",
+    });
+    await providerHydrated;
+
+    const localForm = page.getByTestId("ai-provider-config-local");
+    const localReasoning = page.locator("#ai-local-reasoning");
+    await expect(localReasoning).toHaveValue("");
+    // Same column, same width as the model select above it.
+    const [modelBox, reasoningBox] = await Promise.all([
+      page.locator("#ai-local-model").boundingBox(),
+      localReasoning.boundingBox(),
+    ]);
+    expect(reasoningBox?.x).toBe(modelBox?.x);
+    expect(reasoningBox?.width).toBe(modelBox?.width);
+    expect(
+      await page.evaluate(
+        () =>
+          document.documentElement.scrollWidth <=
+          document.documentElement.clientWidth,
+      ),
+    ).toBe(true);
+
+    await localReasoning.selectOption("none");
+    await localForm.locator('button[type="submit"]').click();
+    await expect.poll(() => patchBodies.length).toBe(1);
+    expect(patchBodies[0].localReasoningEffort).toBe("none");
+
+    await page
+      .getByTestId("ai-active-provider-select")
+      .selectOption("openai-compatible");
+    const compatForm = page.getByTestId("ai-provider-config-openai-compatible");
+    const compatReasoning = page.locator("#ai-compat-reasoning");
+    await expect(compatReasoning).toHaveValue("");
+    await compatReasoning.selectOption("high");
+    await compatForm.locator('button[type="submit"]').click();
+    await expect.poll(() => patchBodies.length).toBe(2);
+    expect(patchBodies[1].compatReasoningEffort).toBe("high");
+    expect(patchBodies[1]).not.toHaveProperty("localReasoningEffort");
+  });
 });
diff --git a/messages/de.json b/messages/de.json
index 0c7173452..5186bb8b6 100644
--- a/messages/de.json
+++ b/messages/de.json
@@ -6080,6 +6080,17 @@
         "title": "Coach-Pläne",
         "description": "Die Pläne, die du mit dem Coach vereinbart hast, zum Lesen oder Entfernen.",
         "open": "Pläne öffnen"
+      },
+      "reasoning": {
+        "label": "Nachdenken",
+        "hint": "Reasoning-Modelle wie Gemma oder Qwen denken nach, bevor sie antworten. Schaltest du es aus, bleibt das ganze Antwortbudget für die Antwort selbst.",
+        "options": {
+          "default": "Standard",
+          "none": "Aus",
+          "low": "Niedrig",
+          "medium": "Mittel",
+          "high": "Hoch"
+        }
       }
     },
     "dashboard": {
diff --git a/messages/en.json b/messages/en.json
index 3cd9aa9a4..fc41483a9 100644
--- a/messages/en.json
+++ b/messages/en.json
@@ -6080,6 +6080,17 @@
         "title": "Coach plans",
         "description": "The plans you agreed with the Coach, to read or remove.",
         "open": "Open plans"
+      },
+      "reasoning": {
+        "label": "Reasoning",
+        "hint": "Reasoning models such as Gemma or Qwen think before they answer. Off leaves the whole answer budget for the answer itself.",
+        "options": {
+          "default": "Default",
+          "none": "Off",
+          "low": "Low",
+          "medium": "Medium",
+          "high": "High"
+        }
       }
     },
     "dashboard": {
diff --git a/messages/es.json b/messages/es.json
index d40131208..90919f624 100644
--- a/messages/es.json
+++ b/messages/es.json
@@ -6080,6 +6080,17 @@
         "title": "Planes del Coach",
         "description": "Los planes que acordaste con el Coach, para leerlos o eliminarlos.",
         "open": "Abrir planes"
+      },
+      "reasoning": {
+        "label": "Razonamiento",
+        "hint": "Los modelos de razonamiento como Gemma o Qwen piensan antes de responder. Si lo desactivas, todo el presupuesto de respuesta se queda para la respuesta.",
+        "options": {
+          "default": "Predeterminado",
+          "none": "Desactivado",
+          "low": "Bajo",
+          "medium": "Medio",
+          "high": "Alto"
+        }
       }
     },
     "dashboard": {
diff --git a/messages/fr.json b/messages/fr.json
index a5d0afa08..5d0c5570d 100644
--- a/messages/fr.json
+++ b/messages/fr.json
@@ -6080,6 +6080,17 @@
         "title": "Plans du Coach",
         "description": "Les plans convenus avec le Coach, à lire ou à supprimer.",
         "open": "Ouvrir les plans"
+      },
+      "reasoning": {
+        "label": "Raisonnement",
+        "hint": "Les modèles de raisonnement comme Gemma ou Qwen réfléchissent avant de répondre. Désactivé, tout le budget de réponse sert à la réponse elle-même.",
+        "options": {
+          "default": "Par défaut",
+          "none": "Désactivé",
+          "low": "Faible",
+          "medium": "Moyen",
+          "high": "Élevé"
+        }
       }
     },
     "dashboard": {
diff --git a/messages/it.json b/messages/it.json
index e0e489863..8654d8fea 100644
--- a/messages/it.json
+++ b/messages/it.json
@@ -6080,6 +6080,17 @@
         "title": "Piani del Coach",
         "description": "I piani concordati con il Coach, da leggere o rimuovere.",
         "open": "Apri i piani"
+      },
+      "reasoning": {
+        "label": "Ragionamento",
+        "hint": "I modelli di ragionamento come Gemma o Qwen pensano prima di rispondere. Se lo disattivi, tutto il budget della risposta resta per la risposta stessa.",
+        "options": {
+          "default": "Predefinito",
+          "none": "Disattivato",
+          "low": "Basso",
+          "medium": "Medio",
+          "high": "Alto"
+        }
       }
     },
     "dashboard": {
diff --git a/messages/ko.json b/messages/ko.json
index e51af7017..ac44f12e5 100644
--- a/messages/ko.json
+++ b/messages/ko.json
@@ -6080,6 +6080,17 @@
         "title": "코치 계획",
         "description": "코치와 합의한 계획을 읽거나 삭제할 수 있습니다.",
         "open": "계획 열기"
+      },
+      "reasoning": {
+        "label": "추론",
+        "hint": "Gemma나 Qwen 같은 추론 모델은 답하기 전에 먼저 생각합니다. 끄면 답변 예산을 모두 답변 자체에 씁니다.",
+        "options": {
+          "default": "기본값",
+          "none": "끄기",
+          "low": "낮음",
+          "medium": "보통",
+          "high": "높음"
+        }
       }
     },
     "dashboard": {
diff --git a/messages/pl.json b/messages/pl.json
index caa7f9245..17a2e68fe 100644
--- a/messages/pl.json
+++ b/messages/pl.json
@@ -6080,6 +6080,17 @@
         "title": "Plany z Coachem",
         "description": "Plany uzgodnione z Coachem, do przeczytania lub usunięcia.",
         "open": "Otwórz plany"
+      },
+      "reasoning": {
+        "label": "Rozumowanie",
+        "hint": "Modele rozumujące, takie jak Gemma czy Qwen, myślą przed odpowiedzią. Po wyłączeniu cały budżet odpowiedzi idzie na samą odpowiedź.",
+        "options": {
+          "default": "Domyślnie",
+          "none": "Wyłączone",
+          "low": "Niskie",
+          "medium": "Średnie",
+          "high": "Wysokie"
+        }
       }
     },
     "dashboard": {
diff --git a/src/components/settings/ai/__tests__/reasoning-effort-field.test.tsx b/src/components/settings/ai/__tests__/reasoning-effort-field.test.tsx
new file mode 100644
index 000000000..0f2f2efd2
--- /dev/null
+++ b/src/components/settings/ai/__tests__/reasoning-effort-field.test.tsx
@@ -0,0 +1,106 @@
+import { describe, expect, it } from "vitest";
+import { renderToStaticMarkup } from "react-dom/server";
+import { QueryClient, QueryClientProvider } from "@tanstack/react-query";
+
+import { I18nProvider } from "@/lib/i18n/context";
+import en from "../../../../../messages/en.json";
+import { CompatProviderForm } from "../compat-provider-form";
+import { LocalProviderForm } from "../local-provider-form";
+import type { UserAIProvider } from "../shared";
+
+/**
+ * #1126 — the Reasoning select on the Local and OpenAI-compatible forms. It
+ * sits right under the model field, offers exactly Default / Off / Low /
+ * Medium / High, and seeds from the value the server stored on the entry.
+ * Saving it is pinned end to end in `e2e/ai-provider-dropdown.spec.ts`.
+ */
+
+function provider(overrides: Partial<UserAIProvider>): UserAIProvider {
+  return {
+    provider: "LOCAL",
+    model: "llama3:8b",
+    baseUrl: "http://ollama.example.org:11434/v1",
+    hasAnthropicKey: false,
+    anthropicKeyPreview: null,
+    hasLocalKey: false,
+    hasOpenaiKey: false,
+    openaiKeyPreview: null,
+    compatBaseUrl: "https://gateway.example.org/v1",
+    compatModel: "qwen3",
+    hasCompatKey: false,
+    responseTimeoutSeconds: null,
+    ...overrides,
+  };
+}
+
+function render(node: React.ReactNode) {
+  const client = new QueryClient({
+    defaultOptions: { queries: { retry: false } },
+  });
+  return renderToStaticMarkup(
+    <QueryClientProvider client={client}>
+      <I18nProvider initialLocale="en">{node}</I18nProvider>
+    </QueryClientProvider>,
+  );
+}
+
+/** The `<select>` element with the given id, as markup. */
+function selectMarkup(html: string, id: string): string {
+  const match = new RegExp(`<select[^>]*\\bid="${id}"`).exec(html);
+  expect(match, `no select #${id}`).not.toBeNull();
+  const start = match!.index;
+  return html.slice(start, html.indexOf("</select>", start));
+}
+
+const OPTION_VALUES = ["", "none", "low", "medium", "high"];
+
+describe.each([
+  {
+    name: "Local",
+    id: "ai-local-reasoning",
+    after: "ai-local-model",
+    form: (p: UserAIProvider) => <LocalProviderForm userProvider={p} />,
+    stored: (v: UserAIProvider["localReasoningEffort"]) => ({
+      localReasoningEffort: v,
+    }),
+  },
+  {
+    name: "OpenAI-compatible",
+    id: "ai-compat-reasoning",
+    after: "ai-compat-model",
+    form: (p: UserAIProvider) => <CompatProviderForm userProvider={p} />,
+    stored: (v: UserAIProvider["compatReasoningEffort"]) => ({
+      compatReasoningEffort: v,
+      provider: "OPENAI_COMPATIBLE",
+    }),
+  },
+])("$name form", ({ id, after, form, stored }) => {
+  it("offers Default, Off, Low, Medium and High under the model field", () => {
+    const html = render(form(provider({})));
+    const select = selectMarkup(html, id);
+    expect(
+      [...select.matchAll(/<option value="([^"]*)"/g)].map((m) => m[1]),
+    ).toEqual(OPTION_VALUES);
+    const r = en.settings.ai.reasoning;
+    for (const label of Object.values(r.options)) {
+      expect(select).toContain(`>${label}</option>`);
+    }
+    expect(html).toContain(`<label`);
+    expect(html).toContain(`for="${id}"`);
+    expect(html).toContain(r.label);
+    expect(html).toContain(r.hint);
+    expect(html.indexOf(`id="${id}"`)).toBeGreaterThan(
+      html.indexOf(`id="${after}"`),
+    );
+  });
+
+  it("seeds Default when nothing is stored, or a payload predates the field", () => {
+    const select = selectMarkup(render(form(provider({}))), id);
+    expect(select).toMatch(/<option value="" selected="">/);
+  });
+
+  it("seeds the stored value", () => {
+    const select = selectMarkup(render(form(provider(stored("none")))), id);
+    expect(select).toMatch(/<option value="none" selected="">/);
+  });
+});
diff --git a/src/components/settings/ai/compat-provider-form.tsx b/src/components/settings/ai/compat-provider-form.tsx
index d584c10df..3e621cf2f 100644
--- a/src/components/settings/ai/compat-provider-form.tsx
+++ b/src/components/settings/ai/compat-provider-form.tsx
@@ -19,7 +19,12 @@ import { apiPatch } from "@/lib/api/api-fetch";
 import { useTranslations } from "@/lib/i18n/context";
 import { aiInputDependentKeys, invalidateKeys } from "@/lib/query-keys";
 
-import { uiToLegacyProviderEnum, type UserAIProvider } from "./shared";
+import { ReasoningEffortField } from "./reasoning-effort-field";
+import {
+  uiToLegacyProviderEnum,
+  type ReasoningEffort,
+  type UserAIProvider,
+} from "./shared";
 
 export function CompatProviderForm({
   userProvider,
@@ -32,6 +37,7 @@ export function CompatProviderForm({
   const [baseUrl, setBaseUrl] = useState("");
   const [apiKey, setApiKey] = useState("");
   const [model, setModel] = useState("");
+  const [reasoning, setReasoning] = useState<ReasoningEffort | null>(null);
   const [msg, setMsg] = useState<string | null>(null);
   const [ok, setOk] = useState(false);
   const submitInFlightRef = useRef(false);
@@ -40,13 +46,14 @@ export function CompatProviderForm({
   // render-time pattern the sibling forms use (no setState-in-effect).
   const seededKey =
     userProvider != null
-      ? `${userProvider.compatBaseUrl ?? ""}|${userProvider.compatModel ?? ""}`
+      ? `${userProvider.compatBaseUrl ?? ""}|${userProvider.compatModel ?? ""}|${userProvider.compatReasoningEffort ?? ""}`
       : null;
   const [previousSeed, setPreviousSeed] = useState<string | null>(null);
   if (seededKey && seededKey !== previousSeed) {
     setPreviousSeed(seededKey);
     setBaseUrl(userProvider?.compatBaseUrl ?? "");
     setModel(userProvider?.compatModel ?? "");
+    setReasoning(userProvider?.compatReasoningEffort ?? null);
   }
 
   const saveMutation = useMutation({
@@ -55,6 +62,7 @@ export function CompatProviderForm({
         provider: uiToLegacyProviderEnum("openai-compatible"),
         compatBaseUrl: baseUrl.trim() || null,
         compatModel: model.trim() || null,
+        compatReasoningEffort: reasoning,
       };
       if (apiKey.trim()) body.compatKey = apiKey.trim();
       await apiPatch("/api/user/ai-provider", body);
@@ -130,6 +138,11 @@ export function CompatProviderForm({
           {t("settings.ai.compat.modelHint")}
         </p>
       </div>
+      <ReasoningEffortField
+        id="ai-compat-reasoning"
+        value={reasoning}
+        onChange={setReasoning}
+      />
 
       <div>
         <Button
diff --git a/src/components/settings/ai/local-provider-form.tsx b/src/components/settings/ai/local-provider-form.tsx
index 63c1c5c68..58d255a2e 100644
--- a/src/components/settings/ai/local-provider-form.tsx
+++ b/src/components/settings/ai/local-provider-form.tsx
@@ -17,10 +17,12 @@ import { apiPatch } from "@/lib/api/api-fetch";
 import { useTranslations } from "@/lib/i18n/context";
 import { aiInputDependentKeys, invalidateKeys } from "@/lib/query-keys";
 
+import { ReasoningEffortField } from "./reasoning-effort-field";
 import {
   CUSTOM_MODEL_SENTINEL,
   LOCAL_MODEL_PRESETS,
   uiToLegacyProviderEnum,
+  type ReasoningEffort,
   type UserAIProvider,
 } from "./shared";
 
@@ -36,17 +38,20 @@ export function LocalProviderForm({
   const [apiKey, setApiKey] = useState("");
   const [modelChoice, setModelChoice] = useState<string>("");
   const [customModel, setCustomModel] = useState("");
+  const [reasoning, setReasoning] = useState<ReasoningEffort | null>(null);
   const [msg, setMsg] = useState<string | null>(null);
   const [ok, setOk] = useState(false);
   const submitInFlightRef = useRef(false);
 
   const seededKey =
     userProvider != null
-      ? `${userProvider.provider ?? ""}|${userProvider.model ?? ""}|${userProvider.baseUrl ?? ""}`
+      ? `${userProvider.provider ?? ""}|${userProvider.model ?? ""}|${userProvider.baseUrl ?? ""}|${userProvider.localReasoningEffort ?? ""}`
       : null;
   const [previousSeed, setPreviousSeed] = useState<string | null>(null);
   if (seededKey && seededKey !== previousSeed) {
     setPreviousSeed(seededKey);
+    // Stored on the chain entry, so it seeds whichever provider is selected.
+    setReasoning(userProvider?.localReasoningEffort ?? null);
     if (userProvider?.provider === "LOCAL") {
       setBaseUrl(userProvider.baseUrl ?? "");
       const saved = userProvider.model ?? "";
@@ -71,6 +76,7 @@ export function LocalProviderForm({
         provider: uiToLegacyProviderEnum("local"),
         baseUrl: baseUrl.trim() || null,
         model: effectiveModel || null,
+        localReasoningEffort: reasoning,
       };
       if (apiKey.trim()) body.localKey = apiKey.trim();
       await apiPatch("/api/user/ai-provider", body);
@@ -168,6 +174,11 @@ export function LocalProviderForm({
           />
         </div>
       )}
+      <ReasoningEffortField
+        id="ai-local-reasoning"
+        value={reasoning}
+        onChange={setReasoning}
+      />
 
       <div>
         <Button
diff --git a/src/components/settings/ai/reasoning-effort-field.tsx b/src/components/settings/ai/reasoning-effort-field.tsx
new file mode 100644
index 000000000..b9bae533f
--- /dev/null
+++ b/src/components/settings/ai/reasoning-effort-field.tsx
@@ -0,0 +1,52 @@
+"use client";
+
+/* ────────────────────────────────────────────────────────────────
+ * Reasoning select (#1126) for the Local and OpenAI-compatible forms.
+ * Same Label + NativeSelect + hint layout as the model field above it.
+ * The empty value is Default: nothing is sent and the model decides.
+ * ──────────────────────────────────────────────────────────────── */
+
+import { Label } from "@/components/ui/label";
+import { NativeSelect } from "@/components/ui/native-select";
+import { useTranslations } from "@/lib/i18n/context";
+
+import type { ReasoningEffort } from "./shared";
+
+export function ReasoningEffortField({
+  id,
+  value,
+  onChange,
+}: {
+  id: string;
+  value: ReasoningEffort | null;
+  onChange: (next: ReasoningEffort | null) => void;
+}) {
+  const { t } = useTranslations();
+  return (
+    <div>
+      <Label htmlFor={id}>{t("settings.ai.reasoning.label")}</Label>
+      <NativeSelect
+        id={id}
+        value={value ?? ""}
+        onChange={(e) =>
+          onChange(
+            e.target.value === "" ? null : (e.target.value as ReasoningEffort),
+          )
+        }
+        className="mt-1"
+        aria-describedby={`${id}-hint`}
+      >
+        <option value="">{t("settings.ai.reasoning.options.default")}</option>
+        <option value="none">{t("settings.ai.reasoning.options.none")}</option>
+        <option value="low">{t("settings.ai.reasoning.options.low")}</option>
+        <option value="medium">
+          {t("settings.ai.reasoning.options.medium")}
+        </option>
+        <option value="high">{t("settings.ai.reasoning.options.high")}</option>
+      </NativeSelect>
+      <p id={`${id}-hint`} className="text-muted-foreground mt-1 text-xs">
+        {t("settings.ai.reasoning.hint")}
+      </p>
+    </div>
+  );
+}
diff --git a/src/components/settings/ai/shared.ts b/src/components/settings/ai/shared.ts
index 2b33eea1f..4c77c27a5 100644
--- a/src/components/settings/ai/shared.ts
+++ b/src/components/settings/ai/shared.ts
@@ -5,6 +5,8 @@
  * this module under `src/components/settings/ai/`.
  */
 
+import type { ReasoningEffort } from "@/lib/ai/reasoning-effort";
+
 export interface InsightsSettings {
   codexStatus: string;
   codexConnectedAt: string | null;
@@ -40,8 +42,15 @@ export interface UserAIProvider {
   hasCompatKey: boolean;
   // v1.22 (#89) — per-user response timeout, in seconds (null = default).
   responseTimeoutSeconds: number | null;
+  // #1126 — reasoning setting of the Local and gateway entries (null =
+  // Default). Absent on a payload from a server older than the field.
+  localReasoningEffort?: ReasoningEffort | null;
+  compatReasoningEffort?: ReasoningEffort | null;
 }
 
+/** #1126 — the `reasoning_effort` values; "Off" is `none`. */
+export type { ReasoningEffort };
+
 /**
  * v1.4.16 phase B2 — provider tags exposed to the UI. Mirrors
  * `PROVIDER_CHAIN_TYPES` server-side; kept as a const-array here to