fix(providers): preserve custom model metadata on edit

packages/web/server/lib/opencode/providers.js

@@ -152,6 +152,37 @@ function validateCustomProviderConfig(providerId, config, options = {}) {
   return { ok: true, value: { providerId, config: normalized } };
 }
 
+function mergeCustomProviderConfig(existingValue, normalizedConfig) {
+  const existing = isPlainObject(existingValue) ? existingValue : {};
+  const existingOptions = isPlainObject(existing.options) ? existing.options : {};
+  const normalizedOptions = isPlainObject(normalizedConfig.options) ? normalizedConfig.options : {};
+  const mergedOptions = { ...existingOptions, ...normalizedOptions };
+  if (!Object.prototype.hasOwnProperty.call(normalizedOptions, 'headers')) {
+    delete mergedOptions.headers;
+  }
+
+  const existingModels = isPlainObject(existing.models) ? existing.models : {};
+  const normalizedModels = isPlainObject(normalizedConfig.models) ? normalizedConfig.models : {};
+  const mergedModels = Object.fromEntries(
+    Object.entries(normalizedModels).map(([modelId, normalizedModel]) => {
+      const existingModel = isPlainObject(existingModels[modelId]) ? existingModels[modelId] : {};
+      const nextModel = isPlainObject(normalizedModel) ? normalizedModel : {};
+      return [modelId, { ...existingModel, ...nextModel }];
+    }),
+  );
+
+  const merged = {
+    ...existing,
+    ...normalizedConfig,
+    options: mergedOptions,
+    models: mergedModels,
+  };
+  if (!Object.prototype.hasOwnProperty.call(normalizedConfig, 'env')) {
+    delete merged.env;
+  }
+  return merged;
+}
+
 /**
  * Persist (create or update) a custom provider block in OpenCode user/project/custom config.
  * Does not write secrets — API keys remain in auth.json via the OpenCode auth API.
@@ -183,8 +214,19 @@ function upsertProviderConfig(providerId, config, workingDirectory, scope = 'use
 
   const targetConfig = getConfigForPath(layers, targetPath);
   const providerConfig = isPlainObject(targetConfig.provider) ? { ...targetConfig.provider } : {};
-  providerConfig[validated.value.providerId] = validated.value.config;
+  const providersAlias = isPlainObject(targetConfig.providers) ? { ...targetConfig.providers } : {};
+  const existingProvider = providerConfig[validated.value.providerId] ?? providersAlias[validated.value.providerId];
+  const mergedConfig = mergeCustomProviderConfig(existingProvider, validated.value.config);
+  providerConfig[validated.value.providerId] = mergedConfig;
   targetConfig.provider = providerConfig;
+  if (Object.prototype.hasOwnProperty.call(providersAlias, validated.value.providerId)) {
+    delete providersAlias[validated.value.providerId];
+    if (Object.keys(providersAlias).length === 0) {
+      delete targetConfig.providers;
+    } else {
+      targetConfig.providers = providersAlias;
+    }
+  }
 
   if (Array.isArray(targetConfig.disabled_providers)) {
     targetConfig.disabled_providers = targetConfig.disabled_providers.filter(
@@ -198,7 +240,7 @@ function upsertProviderConfig(providerId, config, workingDirectory, scope = 'use
   return {
     providerId: validated.value.providerId,
     path: writePath,
-    config: validated.value.config,
+    config: mergedConfig,
   };
 }