fix: resolve writable storage dir for logs/stats on Spaces

src/app/api/chat/route.ts

@@ -68,19 +68,50 @@ async function executeWebSearch(query: string): Promise<string> {
     }
 }
 
-function getWritableBaseDir() {
-    const envDir = process.env.DATA_DIR;
-    if (envDir) return envDir;
+const storageDirPromise = (async () => {
+    const candidates: Array<string | undefined> = [
+        process.env.DATA_DIR,
+        process.env.HF_HOME,
+        process.env.HOME,
+        "/tmp",
+        os.tmpdir(),
+        process.cwd(),
+    ];
+
+    const seen = new Set<string>();
+    const unique = candidates.filter((c): c is string => {
+        if (!c) return false;
+        if (seen.has(c)) return false;
+        seen.add(c);
+        return true;
+    });
 
-    // Hugging Face Spaces provides a writable /data volume; /app is typically read-only.
-    if (process.env.NODE_ENV === "production") return "/data";
+    for (const dir of unique) {
+        try {
+            await fs.mkdir(dir, { recursive: true });
+            const probe = path.join(dir, ".write-probe");
+            await fs.writeFile(probe, "ok", "utf8");
+            await fs.unlink(probe);
+            return dir;
+        } catch {
+            // try next
+        }
+    }
+
+    return os.tmpdir();
+})();
 
-    return process.cwd();
+async function getLogFilePath() {
+    if (process.env.CHAT_LOG_PATH) return process.env.CHAT_LOG_PATH;
+    const baseDir = await storageDirPromise;
+    return path.join(baseDir, "chat-logs.jsonl");
 }
 
-const BASE_DIR = getWritableBaseDir();
-const LOG_FILE = process.env.CHAT_LOG_PATH || path.join(BASE_DIR, "chat-logs.jsonl");
-const USAGE_FILE = process.env.USAGE_STATS_PATH || path.join(BASE_DIR, "usage-stats.json");
+async function getUsageFilePath() {
+    if (process.env.USAGE_STATS_PATH) return process.env.USAGE_STATS_PATH;
+    const baseDir = await storageDirPromise;
+    return path.join(baseDir, "usage-stats.json");
+}
 
 type UsageStats = {
     totalRequests: number;
@@ -90,7 +121,8 @@ type UsageStats = {
 
 async function readUsageStats(): Promise<UsageStats> {
     try {
-        const raw = await fs.readFile(USAGE_FILE, "utf8");
+        const usageFile = await getUsageFilePath();
+        const raw = await fs.readFile(usageFile, "utf8");
         const parsed = JSON.parse(raw) as Partial<UsageStats>;
         return {
             totalRequests: typeof parsed.totalRequests === "number" ? parsed.totalRequests : 0,
@@ -113,8 +145,9 @@ async function writeUsageStats(stats: UsageStats) {
         lastUpdated: stats.lastUpdated,
     };
     try {
-        await fs.mkdir(path.dirname(USAGE_FILE), { recursive: true });
-        await fs.writeFile(USAGE_FILE, JSON.stringify(payload, null, 2), "utf8");
+        const usageFile = await getUsageFilePath();
+        await fs.mkdir(path.dirname(usageFile), { recursive: true });
+        await fs.writeFile(usageFile, JSON.stringify(payload, null, 2), "utf8");
     } catch (error) {
         // Don't fail chat if stats persistence isn't writable
         console.error("Failed to write usage stats:", error);
@@ -137,9 +170,10 @@ async function incrementUsageStats() {
 
 async function appendChatLog(entry: unknown) {
     try {
+        const logFile = await getLogFilePath();
         const line = JSON.stringify(entry) + "\n";
-        await fs.mkdir(path.dirname(LOG_FILE), { recursive: true });
-        await fs.appendFile(LOG_FILE, line, "utf8");
+        await fs.mkdir(path.dirname(logFile), { recursive: true });
+        await fs.appendFile(logFile, line, "utf8");
     } catch (error) {
         // Don't fail chat if logging isn't writable
         console.error("Failed to write chat log:", error);

src/app/api/logs/route.ts

@@ -1,18 +1,35 @@
 import { NextRequest } from "next/server";
 import { promises as fs } from "fs";
+import os from "os";
 import path from "path";
 
 export const runtime = "nodejs";
 
-function getWritableBaseDir() {
-    const envDir = process.env.DATA_DIR;
-    if (envDir) return envDir;
-    if (process.env.NODE_ENV === "production") return "/data";
-    return process.cwd();
-}
+async function resolveLogFilePath() {
+    if (process.env.CHAT_LOG_PATH) return process.env.CHAT_LOG_PATH;
+
+    const candidates = [
+        process.env.DATA_DIR,
+        process.env.HF_HOME,
+        process.env.HOME,
+        "/tmp",
+        os.tmpdir(),
+        process.cwd(),
+    ].filter(Boolean) as string[];
+
+    for (const dir of candidates) {
+        const candidate = path.join(dir, "chat-logs.jsonl");
+        try {
+            await fs.access(candidate);
+            return candidate;
+        } catch {
+            // try next
+        }
+    }
 
-const BASE_DIR = getWritableBaseDir();
-const LOG_FILE = process.env.CHAT_LOG_PATH || path.join(BASE_DIR, "chat-logs.jsonl");
+    // Default location if not present yet
+    return path.join(os.tmpdir(), "chat-logs.jsonl");
+}
 const ADMIN_TOKEN = process.env.ADMIN_TOKEN || "";
 
 function isAuthorized(req: NextRequest) {
@@ -45,7 +62,8 @@ export async function GET(req: NextRequest) {
     const raw = rawParam === "1" || rawParam === "true";
 
     try {
-        const file = await fs.readFile(LOG_FILE, "utf8");
+        const logFile = await resolveLogFilePath();
+        const file = await fs.readFile(logFile, "utf8");
         const lines = file.split(/\r?\n/).filter(Boolean);
         const sliced = lines.slice(Math.max(0, lines.length - tail));
 
@@ -69,12 +87,11 @@ export async function GET(req: NextRequest) {
             headers: { "Content-Type": "application/json" },
         });
     } catch (error) {
-        return new Response(
-            JSON.stringify({
-                error: "Failed to read logs",
-                message: error instanceof Error ? error.message : String(error),
-            }),
-            { status: 500, headers: { "Content-Type": "application/json" } }
-        );
+        const message = error instanceof Error ? error.message : String(error);
+        const status = message.includes("ENOENT") ? 404 : 500;
+        return new Response(JSON.stringify({ error: "Failed to read logs", message }), {
+            status,
+            headers: { "Content-Type": "application/json" },
+        });
     }
 }

src/app/api/stats/route.ts

@@ -1,18 +1,35 @@
 import { NextRequest } from "next/server";
 import { promises as fs } from "fs";
+import os from "os";
 import path from "path";
 
 export const runtime = "nodejs";
 
-function getWritableBaseDir() {
-    const envDir = process.env.DATA_DIR;
-    if (envDir) return envDir;
-    if (process.env.NODE_ENV === "production") return "/data";
-    return process.cwd();
-}
+async function resolveUsageFilePath() {
+    if (process.env.USAGE_STATS_PATH) return process.env.USAGE_STATS_PATH;
+
+    const candidates = [
+        process.env.DATA_DIR,
+        process.env.HF_HOME,
+        process.env.HOME,
+        "/tmp",
+        os.tmpdir(),
+        process.cwd(),
+    ].filter(Boolean) as string[];
 
-const BASE_DIR = getWritableBaseDir();
-const USAGE_FILE = process.env.USAGE_STATS_PATH || path.join(BASE_DIR, "usage-stats.json");
+    for (const dir of candidates) {
+        const candidate = path.join(dir, "usage-stats.json");
+        try {
+            await fs.access(candidate);
+            return candidate;
+        } catch {
+            // try next
+        }
+    }
+
+    // Default location if not present yet
+    return path.join(os.tmpdir(), "usage-stats.json");
+}
 const ADMIN_TOKEN = process.env.ADMIN_TOKEN || "";
 
 type UsageStats = {
@@ -34,7 +51,8 @@ function isAuthorized(req: NextRequest) {
 
 async function readUsageStats(): Promise<UsageStats> {
     try {
-        const raw = await fs.readFile(USAGE_FILE, "utf8");
+        const usageFile = await resolveUsageFilePath();
+        const raw = await fs.readFile(usageFile, "utf8");
         const parsed = JSON.parse(raw) as Partial<UsageStats>;
         return {
             totalRequests: typeof parsed.totalRequests === "number" ? parsed.totalRequests : 0,