Add custom model storage location, harden MCP spawn-failure handling

- Settings -> Ollama Server -> Model storage location lets users pick
  where Ollama downloads/stores models (sets OLLAMA_MODELS and restarts
  the managed Ollama process; warns instead if Ollama is running
  externally, since we can't safely restart a process we didn't start).
- Stability: an MCP stdio server that fails to launch (bad command) now
  fails its initialize/tools-list request immediately instead of hanging
  for the full 30s timeout, since child_process only emits error (not
  exit) for that case.

Author: voidstackloop

README.md

@@ -48,6 +48,7 @@ Beyond chat, Modelforge includes an **agentic mode** — the model can read/writ
 - **GPU offload control** — set how many model layers Ollama offloads to GPU (`num_gpu`) per chat, per project, or as a global default; leave it blank to let Ollama decide automatically.
 - **Pull models directly from Hugging Face** — paste any GGUF model's Hugging Face URL (or `hf.co/user/repo`) into the model search box alongside the curated catalog and Ollama's own library.
 - Models with reliable tool/function-calling support are flagged with a 🔧 badge, so picking a good Agent mode model doesn't require guesswork.
+- **Custom model storage location** — Settings → Ollama Server → "Model storage location" lets you point downloaded models at any folder (e.g. a larger or faster drive) instead of Ollama's default location. If this app started Ollama, it restarts it automatically with the new location; if Ollama is running outside the app, you're told to restart it yourself.
 
 **Customization & control**
 - English and Turkish UI localization.

app/src/main.ts

@@ -1,4 +1,5 @@
 import * as path from "node:path";
+import * as fs from "node:fs";
 import { app, BrowserWindow, ipcMain, IpcMainInvokeEvent, dialog, shell } from "electron";
 import * as ollama from "./ollama-manager";
 import { logger, getLogPath, getLogTail } from "./logger";
@@ -150,6 +151,34 @@ function registerIpcHandlers(): void {
     ipcMain.handle("ollama:start", () => ollama.start());
     ipcMain.handle("ollama:stop", () => ollama.stop());
     ipcMain.handle("ollama:listModels", () => ollama.listModels());
+    ipcMain.handle("ollama:pickModelsDir", async () => {
+        const result = mainWindow
+            ? await dialog.showOpenDialog(mainWindow, { properties: ["openDirectory", "createDirectory"] })
+            : await dialog.showOpenDialog({ properties: ["openDirectory", "createDirectory"] });
+        return result.canceled || result.filePaths.length === 0 ? null : result.filePaths[0];
+    });
+
+    ipcMain.handle("ollama:setModelsDir", async (_event: IpcMainInvokeEvent, dir: string | null) => {
+        if (dir) {
+            requireString(dir, "models directory");
+            try {
+                fs.mkdirSync(dir, { recursive: true });
+                fs.accessSync(dir, fs.constants.W_OK);
+            } catch (err) {
+                return { error: `Can't use that folder: ${(err as Error).message}` };
+            }
+        }
+        settingsStore.saveSettings({ modelsDir: dir ?? undefined });
+        ollama.setModelsDir(dir);
+        try {
+            return await ollama.restartWithCurrentConfig();
+        } catch (err) {
+            const error = err as Error;
+            logger.error(`Failed to restart Ollama after changing models directory: ${error.message}`);
+            return { started: false, error: error.message };
+        }
+    });
+
     ipcMain.handle("ollama:deleteModel", (_event: IpcMainInvokeEvent, name: string) =>
         ollama.deleteModel(requireString(name, "model name"))
     );
@@ -408,6 +437,7 @@ app.whenReady().then(async () => {
     setupMenu(() => mainWindow, () => checkForUpdatesManually(() => mainWindow));
     createWindow();
     ollama.setHost(settingsStore.getSettings().ollamaHost);
+    ollama.setModelsDir(settingsStore.getSettings().modelsDir);
     await ollama.start();
     setupAutoUpdater(() => mainWindow);
     void connectEnabledMcpServers();

app/src/mcp-client.ts

@@ -105,7 +105,13 @@ async function connectStdio(config: McpServerConfig): Promise<Connection> {
         conn.pending.clear();
     });
     proc.on("error", (err) => {
+        // Fires for launch failures (e.g. command not found) — unlike a normal
+        // exit, Node doesn't also emit "exit" in that case, so without this the
+        // pending initialize/tools-list request would just sit until its 30s
+        // timeout instead of failing immediately with a useful message.
         conn.lastError = err.message;
+        for (const { reject } of conn.pending.values()) reject(err);
+        conn.pending.clear();
     });
 
     try {

app/src/ollama-manager.test.ts

@@ -0,0 +1,36 @@
+import { describe, it, expect } from "vitest";
+import { setHost, getHost, setModelsDir, getModelsDir } from "./ollama-manager";
+
+describe("ollama-manager config", () => {
+    it("defaults to the local Ollama host", () => {
+        setHost(undefined);
+        expect(getHost()).toBe("http://127.0.0.1:11434");
+    });
+
+    it("trims a custom host and strips trailing slashes", () => {
+        setHost("  http://example.com:11434/  ");
+        expect(getHost()).toBe("http://example.com:11434");
+        setHost(undefined); // reset for other tests
+    });
+
+    it("falls back to the default host for an empty string", () => {
+        setHost("");
+        expect(getHost()).toBe("http://127.0.0.1:11434");
+    });
+
+    it("has no models directory override by default", () => {
+        setModelsDir(undefined);
+        expect(getModelsDir()).toBeUndefined();
+    });
+
+    it("stores a trimmed models directory", () => {
+        setModelsDir("  /data/models  ");
+        expect(getModelsDir()).toBe("/data/models");
+        setModelsDir(undefined); // reset for other tests
+    });
+
+    it("clears the models directory override for an empty string", () => {
+        setModelsDir("");
+        expect(getModelsDir()).toBeUndefined();
+    });
+});

app/src/ollama-manager.ts

@@ -5,6 +5,7 @@ import type { ChatMessage, ChatChunk, ChatOptions, ToolDefinition } from "./prov
 
 const DEFAULT_HOST = "http://127.0.0.1:11434";
 let HOST = DEFAULT_HOST;
+let MODELS_DIR: string | undefined;
 let child: ChildProcess | null = null;
 let weStartedIt = false;
 
@@ -16,6 +17,17 @@ export function getHost(): string {
     return HOST;
 }
 
+// Ollama reads its models directory from the OLLAMA_MODELS env var at
+// process launch — there's no way to change it for an already-running
+// server, so this only takes effect the next time we spawn `ollama serve`.
+export function setModelsDir(dir: string | null | undefined): void {
+    MODELS_DIR = dir && dir.trim() ? dir.trim() : undefined;
+}
+
+export function getModelsDir(): string | undefined {
+    return MODELS_DIR;
+}
+
 function isLocalHost(): boolean {
     try {
         const { hostname } = new URL(HOST);
@@ -71,7 +83,10 @@ export async function start(): Promise<OllamaStartResult> {
     }
 
     try {
-        child = spawn("ollama", ["serve"], { stdio: "ignore" });
+        child = spawn("ollama", ["serve"], {
+            stdio: "ignore",
+            env: MODELS_DIR ? { ...process.env, OLLAMA_MODELS: MODELS_DIR } : process.env,
+        });
         weStartedIt = true;
 
         child.on("exit", () => {
@@ -104,6 +119,29 @@ export function stop(): void {
     }
 }
 
+export interface RestartResult extends OllamaStartResult {
+    // true when Ollama is running but wasn't launched by this app (started
+    // externally, or from before the models directory was changed this
+    // session) — we can't safely kill a process we didn't start, so the new
+    // location won't take effect until the user restarts Ollama themselves.
+    external?: boolean;
+}
+
+export async function restartWithCurrentConfig(): Promise<RestartResult> {
+    if (child && weStartedIt) {
+        stop();
+        for (let i = 0; i < 10; i++) {
+            await sleep(300);
+            if (!(await isRunning())) break;
+        }
+        return start();
+    }
+    if (await isRunning()) {
+        return { started: false, external: true };
+    }
+    return start();
+}
+
 // Ollama error responses are JSON like {"error": "..."} — surface that text
 // instead of just the HTTP status so users see something actionable
 // ("model 'foo' not found" beats "Failed to list models: 404").

app/src/preload.ts

@@ -1,5 +1,5 @@
 import { contextBridge, ipcRenderer } from "electron";
-import type { PullProgress } from "./ollama-manager";
+import type { PullProgress, RestartResult } from "./ollama-manager";
 import type { AttachedFile, MediaAttachment } from "./file-reader";
 import type { ChatMessage, ChatChunk, ChatOptions, ProviderId } from "./providers/types";
 import type { McpServerConfig, McpServerStatus } from "./mcp-client";
@@ -26,6 +26,8 @@ contextBridge.exposeInMainWorld("api", {
         stop: () => ipcRenderer.invoke("ollama:stop"),
         listModels: () => ipcRenderer.invoke("ollama:listModels"),
         deleteModel: (name: string) => ipcRenderer.invoke("ollama:deleteModel", name),
+        pickModelsDir: (): Promise<string | null> => ipcRenderer.invoke("ollama:pickModelsDir"),
+        setModelsDir: (dir: string | null): Promise<RestartResult> => ipcRenderer.invoke("ollama:setModelsDir", dir),
 
         pullModel: (name: string, onProgress: (chunk: PullProgress) => void) => {
             const requestId = randomId();

app/src/settings-store.ts

@@ -23,6 +23,9 @@ export interface PromptPreset {
 export interface AppSettings {
     defaultModel: string | null;
     ollamaHost: string;
+    // undefined = Ollama's own default location. Only takes effect the next
+    // time this app (re)starts a local `ollama serve` process.
+    modelsDir?: string;
     temperature: number;
     topP: number;
     maxTokens: number;

frontend/src/lib/translations.ts

@@ -114,6 +114,13 @@ export interface Dictionary {
     runLint: string;
     runFormat: string;
     newFile: string;
+    modelsDir: string;
+    modelsDirHint: string;
+    modelsDirDefault: string;
+    chooseFolder: string;
+    modelsDirApplied: string;
+    modelsDirFailed: string;
+    modelsDirExternalWarning: string;
     resetToDefault: string;
     usingCustomPrompt: string;
     dataManagement: string;
@@ -266,6 +273,13 @@ export const en: Dictionary = {
     runLint: "Lint",
     runFormat: "Format",
     newFile: "New file",
+    modelsDir: "Model storage location",
+    modelsDirHint: "Where Ollama downloads and stores model files. Changing this restarts Ollama (only if this app started it) — running downloads will be interrupted.",
+    modelsDirDefault: "Default (Ollama's own location)",
+    chooseFolder: "Choose folder...",
+    modelsDirApplied: "Applied — Ollama restarted with the new location.",
+    modelsDirFailed: "Couldn't restart Ollama with the new location. Try starting it manually.",
+    modelsDirExternalWarning: "Saved, but Ollama is running outside this app — restart it manually (with OLLAMA_MODELS set to this folder) for the change to take effect.",
     resetToDefault: "Reset to default",
     usingCustomPrompt: "Custom prompt for this chat",
     dataManagement: "Data management",
@@ -426,6 +440,13 @@ export const tr: Dictionary = {
     runLint: "Lint",
     runFormat: "Biçimlendir",
     newFile: "Yeni dosya",
+    modelsDir: "Model depolama konumu",
+    modelsDirHint: "Ollama'nın model dosyalarını indirdiği ve sakladığı yer. Bunu değiştirmek Ollama'yı yeniden başlatır (yalnızca bu uygulama başlattıysa) — devam eden indirmeler kesintiye uğrar.",
+    modelsDirDefault: "Varsayılan (Ollama'nın kendi konumu)",
+    chooseFolder: "Klasör seç...",
+    modelsDirApplied: "Uygulandı — Ollama yeni konumla yeniden başlatıldı.",
+    modelsDirFailed: "Ollama yeni konumla yeniden başlatılamadı. Elle başlatmayı deneyin.",
+    modelsDirExternalWarning: "Kaydedildi, ancak Ollama bu uygulamanın dışında çalışıyor — değişikliğin etkili olması için Ollama'yı bu klasör OLLAMA_MODELS olarak ayarlanmış şekilde elle yeniden başlatın.",
     resetToDefault: "Varsayılana dön",
     usingCustomPrompt: "Bu sohbet için özel istem",
     dataManagement: "Veri yönetimi",

frontend/src/pages/Settings.tsx

@@ -110,6 +110,8 @@ export default function Settings() {
     const [userDataPath, setUserDataPath] = useState<string | null>(null);
     const [importMessage, setImportMessage] = useState<string | null>(null);
     const [ollamaHostInput, setOllamaHostInput] = useState("");
+    const [modelsDirStatus, setModelsDirStatus] = useState<string | null>(null);
+    const [changingModelsDir, setChangingModelsDir] = useState(false);
     const [newPresetName, setNewPresetName] = useState("");
     const [editingPresetId, setEditingPresetId] = useState<string | null>(null);
     const [editDraftName, setEditDraftName] = useState("");
@@ -210,6 +212,40 @@ export default function Settings() {
         refreshInstalled();
     }
 
+    async function chooseModelsDir() {
+        const dir = await window.api.ollama.pickModelsDir();
+        if (!dir) return;
+        setChangingModelsDir(true);
+        setModelsDirStatus(null);
+        const result = await window.api.ollama.setModelsDir(dir);
+        if (result.error) {
+            setModelsDirStatus(result.error);
+        } else {
+            const updated = await window.api.settings.get();
+            setSettings(updated);
+            setModelsDirStatus(
+                result.external ? t.modelsDirExternalWarning : result.started || result.alreadyRunning ? t.modelsDirApplied : t.modelsDirFailed
+            );
+            window.api.ollama.status().then(setRunning);
+            refreshInstalled();
+        }
+        setChangingModelsDir(false);
+    }
+
+    async function resetModelsDir() {
+        setChangingModelsDir(true);
+        setModelsDirStatus(null);
+        const result = await window.api.ollama.setModelsDir(null);
+        setModelsDirStatus(
+            result.external ? t.modelsDirExternalWarning : result.started || result.alreadyRunning ? t.modelsDirApplied : t.modelsDirFailed
+        );
+        const updated = await window.api.settings.get();
+        setSettings(updated);
+        window.api.ollama.status().then(setRunning);
+        refreshInstalled();
+        setChangingModelsDir(false);
+    }
+
     async function toggleServer() {
         if (running) {
             await window.api.ollama.stop();
@@ -454,6 +490,39 @@ export default function Settings() {
                                     </Button>
                                 </div>
                             </SettingsRow>
+                            <SettingsRow label={t.modelsDir} description={t.modelsDirHint} stacked>
+                                <div className="flex flex-wrap items-center gap-2">
+                                    <span className="truncate rounded border border-border bg-muted px-2 py-1 font-mono text-xs">
+                                        {settings?.modelsDir ?? t.modelsDirDefault}
+                                    </span>
+                                    <Button
+                                        size="sm"
+                                        variant="outline"
+                                        disabled={changingModelsDir}
+                                        onClick={chooseModelsDir}
+                                        className="gap-1.5"
+                                    >
+                                        {changingModelsDir ? (
+                                            <Loader2 className="size-3.5 animate-spin" />
+                                        ) : (
+                                            <FolderOpen className="size-3.5" />
+                                        )}
+                                        {t.chooseFolder}
+                                    </Button>
+                                    {settings?.modelsDir && (
+                                        <Button
+                                            size="sm"
+                                            variant="ghost"
+                                            disabled={changingModelsDir}
+                                            onClick={resetModelsDir}
+                                            className="text-xs text-muted-foreground"
+                                        >
+                                            {t.resetToDefault}
+                                        </Button>
+                                    )}
+                                </div>
+                                {modelsDirStatus && <p className="text-xs text-muted-foreground">{modelsDirStatus}</p>}
+                            </SettingsRow>
                         </SettingsSection>
 
                         <SettingsSection title={t.appearance}>

frontend/src/types/electron.d.ts

@@ -145,6 +145,7 @@ export interface AppSettings {
   ttsVoiceURI?: string;
   ttsAutoRead?: boolean;
   mcpServers?: McpServerConfig[];
+  modelsDir?: string;
 }
 
 export interface ChatOptions {
@@ -167,6 +168,10 @@ export interface OllamaStartResult {
   error?: string;
 }
 
+export interface RestartResult extends OllamaStartResult {
+  external?: boolean;
+}
+
 export interface ChatSession {
   id: string;
   title: string;
@@ -244,6 +249,8 @@ export interface ElectronApi {
     stop: () => Promise<void>;
     listModels: () => Promise<OllamaModel[]>;
     deleteModel: (name: string) => Promise<{ deleted: boolean }>;
+    pickModelsDir: () => Promise<string | null>;
+    setModelsDir: (dir: string | null) => Promise<RestartResult>;
     pullModel: (name: string, onProgress: (chunk: PullProgress) => void) => Promise<{ done: boolean; error?: string }>;
   };
   chat: {