fix: repair incomplete config by merging defaults instead of rejecting

When config.json has valid JSON but is missing required fields (e.g.
defaultProvider or providers), merge defaults into the raw object
instead of discarding it entirely. This preserves pool accounts,
provider configs, and other user data that would otherwise be lost
when a single field is missing.

Only truly unrecoverable configs (invalid JSON, merge still fails)
fall back to backup + default.

Author: lidge-jun

src/config.ts

@@ -93,7 +93,26 @@ export function loadConfig(): OcxConfig {
   }
   try {
     const raw = readFileSync(configPath, "utf-8");
-    return configSchema.parse(JSON.parse(raw)) as OcxConfig;
+    const parsed = JSON.parse(raw);
+    const result = configSchema.safeParse(parsed);
+    if (result.success) return result.data as OcxConfig;
+    // Schema validation failed — merge defaults into the raw object instead of
+    // discarding it entirely, so pool accounts and providers survive a missing
+    // field like defaultProvider.
+    const defaults = getDefaultConfig();
+    const merged = { ...defaults, ...parsed };
+    // Ensure providers from both sides survive
+    if (parsed.providers && defaults.providers) {
+      merged.providers = { ...defaults.providers, ...parsed.providers };
+    }
+    const retryResult = configSchema.safeParse(merged);
+    if (retryResult.success) {
+      warnConfigRepaired(configPath, result.error);
+      return retryResult.data as OcxConfig;
+    }
+    // Merge couldn't fix it — truly broken config
+    warnAndBackupInvalidConfig(configPath, result.error);
+    return getDefaultConfig();
   } catch (error) {
     warnAndBackupInvalidConfig(configPath, error);
     return getDefaultConfig();
@@ -181,6 +200,13 @@ export function removePid(): void {
   } catch { /* ignore */ }
 }
 
+function warnConfigRepaired(configPath: string, error: z.ZodError): void {
+  if (warnedConfigFallbacks.has(configPath)) return;
+  warnedConfigFallbacks.add(configPath);
+  const fields = error.issues.map(i => i.path.join(".") || "config").join(", ");
+  console.error(`opencodex config at ${configPath}: repaired missing field(s) [${fields}] with defaults. Your providers and accounts are preserved.`);
+}
+
 function warnAndBackupInvalidConfig(configPath: string, error: unknown): void {
   if (warnedConfigFallbacks.has(configPath)) return;
   warnedConfigFallbacks.add(configPath);

tests/config.test.ts

@@ -77,18 +77,21 @@ describe("opencodex config defaults", () => {
     }
   });
 
-  test("backs up structurally invalid config before falling back to defaults", () => {
+  test("repairs structurally incomplete config by merging defaults instead of rejecting", () => {
     writeConfig({ port: 10100 });
     const errorSpy = spyOn(console, "error").mockImplementation(() => {});
 
     try {
       const loaded = loadConfig();
 
-      expect(loaded).toEqual(getDefaultConfig());
+      // Merge should fill in missing providers and defaultProvider from defaults
+      expect(loaded.port).toBe(10100);
+      expect(loaded.defaultProvider).toBe("openai");
+      expect(loaded.providers).toBeDefined();
+      // No backup created — config was repaired, not rejected
       const backups = backupNames();
-      expect(backups).toHaveLength(1);
-      expect(JSON.parse(readFileSync(join(testDir, backups[0]), "utf-8"))).toEqual({ port: 10100 });
-      expect(errorSpy).toHaveBeenCalledWith(expect.stringContaining("providers"));
+      expect(backups).toHaveLength(0);
+      expect(errorSpy).toHaveBeenCalledWith(expect.stringContaining("repaired"));
     } finally {
       errorSpy.mockRestore();
     }