refactor(open-sse): registry consolidation + DRY media/oauth/adhoc cleanup

- Single-source registry: oauth clientId/tokenUrl, usage URLs, image/embed
  configs, search defaultModel, codex fixedPort, google token url derive.
- Remove 29 unused OmniRoute providers (registry 100→71); media intact.
- De-adhoc: codex literals → registry format/oauth flags; reasoningInject,
  image/embed openrouter headers + xai bodyFields config-driven.
- Add REGISTRY_TEMPLATE.js + expand PROVIDER_DEFAULTS/schema JSDoc.
- Baselines updated; PROVIDERS 62 + alias 90 byte-for-byte, golden snapshots.

Co-authored-by: Cursor <cursoragent@cursor.com>

open-sse/handlers/search/chatSearch.js

@@ -2,6 +2,10 @@
  * Wrap chat-completions endpoints (with built-in web search) into the unified
  * /v1/search response format. Supports gemini, openai, xai, kimi, minimax, perplexity.
  */
+import { PROVIDER_MEDIA } from "../../providers/index.js";
+
+// Default search model derives from registry searchViaChat (single source)
+const searchModel = (id) => PROVIDER_MEDIA[id]?.searchViaChat?.defaultModel;
 
 const REQUEST_TIMEOUT_MS = 15000;
 const DEFAULT_MAX_RESULTS = 10;
@@ -45,7 +49,6 @@ const CHAT_SEARCH_CONFIG = {
   gemini: {
     endpoint: (model) =>
       `https://generativelanguage.googleapis.com/v1beta/models/${model}:generateContent`,
-    defaultModel: "gemini-2.5-flash",
     buildBody: (query) => ({
       contents: [{ role: "user", parts: [{ text: query }] }],
       tools: [{ google_search: {} }]
@@ -71,7 +74,6 @@ const CHAT_SEARCH_CONFIG = {
 
   openai: {
     endpoint: () => "https://api.openai.com/v1/chat/completions",
-    defaultModel: "gpt-4o-mini",
     buildBody: (query, model) => {
       const body = {
         model,
@@ -106,7 +108,6 @@ const CHAT_SEARCH_CONFIG = {
 
   xai: {
     endpoint: () => "https://api.x.ai/v1/responses",
-    defaultModel: "grok-4.20-reasoning",
     buildBody: (query, model) => ({
       model,
       input: [{ role: "user", content: query }],
@@ -146,7 +147,6 @@ const CHAT_SEARCH_CONFIG = {
 
   kimi: {
     endpoint: () => "https://api.moonshot.cn/v1/chat/completions",
-    defaultModel: "kimi-k2.5",
     buildBody: (query, model) => ({
       model,
       messages: [{ role: "user", content: query }],
@@ -196,7 +196,6 @@ const CHAT_SEARCH_CONFIG = {
 
   minimax: {
     endpoint: () => "https://api.minimaxi.com/v1/text/chatcompletion_v2",
-    defaultModel: "MiniMax-M2.7",
     buildBody: (query, model) => ({
       model,
       messages: [{ role: "user", content: query }],
@@ -255,7 +254,6 @@ const CHAT_SEARCH_CONFIG = {
 
   perplexity: {
     endpoint: () => "https://api.perplexity.ai/chat/completions",
-    defaultModel: "sonar",
     buildBody: (query, model) => ({
       model,
       messages: [{ role: "user", content: query }]
@@ -324,7 +322,7 @@ export async function handleChatSearch({
     Number.isFinite(maxResults) && maxResults > 0
       ? Math.floor(maxResults)
       : DEFAULT_MAX_RESULTS;
-  const useModel = model || cfg.defaultModel;
+  const useModel = model || searchModel(provider);
   const url = cfg.endpoint(useModel);
   const body = cfg.buildBody(query, useModel);
   const headers = cfg.buildHeaders(token);