refactor(open-sse): translator DRY + schema enums, bug fixes, dead code cleanup

- Bug B1-B7: media UI m.kind||m.type, serviceKinds, gemini mediaPriority, schema kind, models/info lookup by kind
- Dead code D1-D6: safeParseJSON, drop PROVIDER_ENDPOINTS, orphan fetcher, GITHUB_CONFIG derive, getProviderConfig internal, legacy kiro file
- Translator concerns: toOpenAIUsage, toOpenAIFinish (gemini/kiro/ollama + fix kiro tool finish), thinking effort maps
- Reorg helpers/ → concerns/ (logic) + formats/ (per-format) + schema/ (pure enums: roles/blocks/finishReasons/defaults)
- Wire ~280 hardcoded role/block/finish/default literals to schema enums across 20+ files
- collapseTextParts + extractTextContent dedup
- Normalize translator fn names to openaiToXRequest / xToOpenAIResponse
- Golden tests lock behavior; 0 regression (byte-for-byte providers/alias, 26=26 known fails)

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

open-sse/translator/request/gemini-to-openai.js

@@ -1,7 +1,9 @@
 import { register } from "../index.js";
 import { FORMATS } from "../formats.js";
-import { adjustMaxTokens } from "../helpers/maxTokensHelper.js";
-import { encodeDataUri } from "../helpers/imageHelper.js";
+import { adjustMaxTokens } from "../formats/maxTokens.js";
+import { encodeDataUri } from "../concerns/image.js";
+import { collapseTextParts } from "../concerns/message.js";
+import { ROLE, GEMINI_ROLE, OPENAI_BLOCK } from "../schema/index.js";
 
 // Convert Gemini request to OpenAI format
 export function geminiToOpenAIRequest(model, body, stream) {
@@ -31,7 +33,7 @@ export function geminiToOpenAIRequest(model, body, stream) {
     const systemText = extractGeminiText(body.systemInstruction);
     if (systemText) {
       result.messages.push({
-        role: "system",
+        role: ROLE.SYSTEM,
         content: systemText
       });
     }
@@ -54,7 +56,7 @@ export function geminiToOpenAIRequest(model, body, stream) {
       if (tool.functionDeclarations) {
         for (const func of tool.functionDeclarations) {
           result.tools.push({
-            type: "function",
+            type: OPENAI_BLOCK.FUNCTION,
             function: {
               name: func.name,
               description: func.description || "",
@@ -71,7 +73,7 @@ export function geminiToOpenAIRequest(model, body, stream) {
 
 // Convert Gemini content to OpenAI message
 function convertGeminiContent(content) {
-  const role = content.role === "user" ? "user" : "assistant";
+  const role = content.role === GEMINI_ROLE.USER ? ROLE.USER : ROLE.ASSISTANT;
   
   if (!content.parts || !Array.isArray(content.parts)) {
     return null;
@@ -82,12 +84,12 @@ function convertGeminiContent(content) {
 
   for (const part of content.parts) {
     if (part.text !== undefined) {
-      parts.push({ type: "text", text: part.text });
+      parts.push({ type: OPENAI_BLOCK.TEXT, text: part.text });
     }
 
     if (part.inlineData) {
       parts.push({
-        type: "image_url",
+        type: OPENAI_BLOCK.IMAGE_URL,
         image_url: {
           url: encodeDataUri(part.inlineData.mimeType, part.inlineData.data)
         }
@@ -97,7 +99,7 @@ function convertGeminiContent(content) {
     if (part.functionCall) {
       toolCalls.push({
         id: `call_${Date.now()}_${Math.random().toString(36).slice(2, 8)}`,
-        type: "function",
+        type: OPENAI_BLOCK.FUNCTION,
         function: {
           name: part.functionCall.name,
           arguments: JSON.stringify(part.functionCall.args || {})
@@ -107,7 +109,7 @@ function convertGeminiContent(content) {
 
     if (part.functionResponse) {
       return {
-        role: "tool",
+        role: ROLE.TOOL,
         tool_call_id: part.functionResponse.id || part.functionResponse.name,
         content: JSON.stringify(part.functionResponse.response?.result || part.functionResponse.response || {})
       };
@@ -115,7 +117,7 @@ function convertGeminiContent(content) {
   }
 
   if (toolCalls.length > 0) {
-    const result = { role: "assistant" };
+    const result = { role: ROLE.ASSISTANT };
     if (parts.length > 0) {
       result.content = parts.length === 1 ? parts[0].text : parts;
     }
@@ -126,7 +128,7 @@ function convertGeminiContent(content) {
   if (parts.length > 0) {
     return {
       role,
-      content: parts.length === 1 && parts[0].type === "text" ? parts[0].text : parts
+      content: collapseTextParts(parts)
     };
   }