diff --git a/src/main/ai/LocalOllamaProvider.ts b/src/main/ai/LocalOllamaProvider.ts
index 44ce522..b276b23 100644
--- a/src/main/ai/LocalOllamaProvider.ts
+++ b/src/main/ai/LocalOllamaProvider.ts
@@ -2,6 +2,7 @@ import { request } from 'undici';
 import { parseAiResponse, type AiResponse } from './schema.js';
 import { buildPrompt } from './prompt.js';
 import type { GenerateInput, HealthResult, InferenceProvider } from './InferenceProvider.js';
+import { DEFAULT_OLLAMA_ENDPOINT, DEFAULT_OLLAMA_MODEL } from '../../shared/constants.js';
 
 export interface LocalOllamaOptions {
   endpoint?: string;
@@ -21,8 +22,8 @@ export class LocalOllamaProvider implements InferenceProvider {
   private abortController: AbortController | null = null;
 
   constructor(opts: LocalOllamaOptions = {}) {
-    this.endpoint = opts.endpoint ?? 'http://localhost:11434';
-    this.model = opts.model ?? 'gemma4:e4b';
+    this.endpoint = opts.endpoint ?? DEFAULT_OLLAMA_ENDPOINT;
+    this.model = opts.model ?? DEFAULT_OLLAMA_MODEL;
     this.timeoutMs = opts.timeoutMs ?? 120_000;
     this.temperature = opts.temperature ?? 0.2;
     this.numPredict = opts.numPredict ?? 512;
diff --git a/src/main/index.ts b/src/main/index.ts
index 14a16c1..f4f3932 100644
--- a/src/main/index.ts
+++ b/src/main/index.ts
@@ -31,6 +31,7 @@ import { ImportService } from './services/ImportService.js';
 import { SyncService } from './services/SyncService.js';
 import { TelemetryService } from './services/TelemetryService.js';
 import { SettingsService } from './services/SettingsService.js';
+import { DEFAULT_OLLAMA_ENDPOINT, DEFAULT_OLLAMA_MODEL } from '../shared/constants.js';
 
 const HIDDEN_ARG = '--hidden';
 const startedHidden = process.argv.includes(HIDDEN_ARG);
@@ -70,8 +71,8 @@ app.whenReady().then(async () => {
 
   const resolvedEndpoint = settings.ollama?.endpoint
                          ?? process.env.INKLING_OLLAMA_ENDPOINT
-                         ?? 'http://localhost:11434';
-  const resolvedModel = settings.ollama?.model ?? 'gemma4:e4b';
+                         ?? DEFAULT_OLLAMA_ENDPOINT;
+  const resolvedModel = settings.ollama?.model ?? DEFAULT_OLLAMA_MODEL;
 
   logger.info('ai.endpoint', {
     endpoint: resolvedEndpoint,
diff --git a/src/main/ipc/inboxApi.ts b/src/main/ipc/inboxApi.ts
index 644317e..97a9819 100644
--- a/src/main/ipc/inboxApi.ts
+++ b/src/main/ipc/inboxApi.ts
@@ -158,7 +158,11 @@ export function registerInboxApi(deps: InboxIpcDeps): void {
     const trial = new LocalOllamaProvider({ endpoint: value.endpoint, model: value.model });
     const r = await trial.healthCheck();
     if (!r.ok) return { ok: false, reason: r.reason ?? 'unknown' };
-    await deps.settings.setOllama(value);
+    try {
+      await deps.settings.setOllama(value);
+    } catch (e) {
+      return { ok: false, reason: `persist failed: ${(e as Error).message}` };
+    }
     deps.providerHolder.get().abort?.();
     deps.providerHolder.replace(trial);
     // 즉시 health 재확인 → onUpdate callback 통해 OllamaBanner 자동 갱신
diff --git a/src/renderer/inbox/components/OllamaSettingsModal.tsx b/src/renderer/inbox/components/OllamaSettingsModal.tsx
index ac39122..5eadc22 100644
--- a/src/renderer/inbox/components/OllamaSettingsModal.tsx
+++ b/src/renderer/inbox/components/OllamaSettingsModal.tsx
@@ -1,5 +1,6 @@
 import React, { useEffect, useState } from 'react';
 import { inboxApi } from '../api.js';
+import { DEFAULT_OLLAMA_ENDPOINT, DEFAULT_OLLAMA_MODEL } from '../../../shared/constants.js';
 
 interface Props {
   open: boolean;
@@ -7,8 +8,8 @@ interface Props {
 }
 
 export function OllamaSettingsModal({ open, onClose }: Props): React.ReactElement | null {
-  const [endpoint, setEndpoint] = useState('http://localhost:11434');
-  const [model, setModel] = useState('gemma4:e4b');
+  const [endpoint, setEndpoint] = useState(DEFAULT_OLLAMA_ENDPOINT);
+  const [model, setModel] = useState(DEFAULT_OLLAMA_MODEL);
   const [error, setError] = useState<string | null>(null);
   const [saving, setSaving] = useState(false);
 
@@ -27,6 +28,7 @@ export function OllamaSettingsModal({ open, onClose }: Props): React.ReactElemen
   if (!open) return null;
 
   async function handleSave() {
+    if (saving) return;  // m4 fix: synchronous double-click 가드
     setSaving(true);
     setError(null);
     try {
@@ -44,10 +46,17 @@ export function OllamaSettingsModal({ open, onClose }: Props): React.ReactElemen
   }
 
   return (
-    <div style={{
-      position: 'fixed', inset: 0, background: 'rgba(0,0,0,0.4)',
-      display: 'flex', alignItems: 'center', justifyContent: 'center', zIndex: 1000
-    }}>
+    <div
+      onKeyDown={(e) => {
+        if (e.key === 'Escape' && !saving) onClose();
+        if (e.key === 'Enter' && !saving) void handleSave();
+      }}
+      tabIndex={-1}
+      style={{
+        position: 'fixed', inset: 0, background: 'rgba(0,0,0,0.4)',
+        display: 'flex', alignItems: 'center', justifyContent: 'center', zIndex: 1000
+      }}
+    >
       <div style={{
         background: '#fff', borderRadius: 8, padding: 20, minWidth: 400, maxWidth: 500,
         boxShadow: '0 4px 16px rgba(0,0,0,0.2)'
@@ -62,6 +71,7 @@ export function OllamaSettingsModal({ open, onClose }: Props): React.ReactElemen
             value={endpoint}
             onChange={(e) => setEndpoint(e.target.value)}
             placeholder="http://localhost:11434"
+            autoFocus
             style={{ width: '100%', padding: '6px 8px', fontSize: 13, border: '1px solid #ccc', borderRadius: 4 }}
             disabled={saving}
           />
diff --git a/src/shared/constants.ts b/src/shared/constants.ts
new file mode 100644
index 0000000..a258531
--- /dev/null
+++ b/src/shared/constants.ts
@@ -0,0 +1,2 @@
+export const DEFAULT_OLLAMA_MODEL = 'gemma4:e4b';
+export const DEFAULT_OLLAMA_ENDPOINT = 'http://localhost:11434';