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/schema/blocks.js

@@ -0,0 +1,41 @@
+// Content-block "type" discriminators — fixed per format. Pure data (no logic).
+
+// OpenAI chat content blocks + tool_call wrapper.
+export const OPENAI_BLOCK = {
+  TEXT: "text",
+  IMAGE_URL: "image_url",
+  IMAGE: "image",
+  INPUT_AUDIO: "input_audio",
+  AUDIO_URL: "audio_url",
+  FUNCTION: "function",
+};
+
+// Claude content blocks.
+export const CLAUDE_BLOCK = {
+  TEXT: "text",
+  IMAGE: "image",
+  TOOL_USE: "tool_use",
+  TOOL_RESULT: "tool_result",
+  THINKING: "thinking",
+  REDACTED_THINKING: "redacted_thinking",
+};
+
+// OpenAI Responses API item types.
+export const RESPONSES_ITEM = {
+  MESSAGE: "message",
+  FUNCTION_CALL: "function_call",
+  FUNCTION_CALL_OUTPUT: "function_call_output",
+  REASONING: "reasoning",
+  OUTPUT_TEXT: "output_text",
+  INPUT_TEXT: "input_text",
+  INPUT_IMAGE: "input_image",
+  SUMMARY_TEXT: "summary_text",
+};
+
+// Valid OpenAI block types (used by filterToOpenAIFormat).
+export const VALID_OPENAI_CONTENT_TYPES = [
+  OPENAI_BLOCK.TEXT, OPENAI_BLOCK.IMAGE_URL, OPENAI_BLOCK.IMAGE, OPENAI_BLOCK.INPUT_AUDIO, OPENAI_BLOCK.AUDIO_URL,
+];
+export const VALID_OPENAI_MESSAGE_TYPES = [
+  OPENAI_BLOCK.TEXT, OPENAI_BLOCK.IMAGE_URL, OPENAI_BLOCK.IMAGE, "tool_calls", CLAUDE_BLOCK.TOOL_RESULT,
+];

open-sse/translator/schema/defaults.js

@@ -0,0 +1,7 @@
+// Shared translator default values (magic strings used across multiple translators).
+
+// Fallback model id when upstream chunk omits one.
+export const MODEL_FALLBACK = "unknown";
+
+// Default image mime when source omits it (base64 blobs without a declared type).
+export const DEFAULT_IMAGE_MIME = "image/png";

open-sse/translator/schema/finishReasons.js

@@ -0,0 +1,27 @@
+// Finish/stop reason enums. Pure data — mapping LOGIC lives in concerns/finishReason.js.
+
+// OpenAI finish_reason values (the hub format; shared across all response translators).
+export const OPENAI_FINISH = {
+  STOP: "stop",
+  LENGTH: "length",
+  TOOL_CALLS: "tool_calls",
+  CONTENT_FILTER: "content_filter",
+};
+
+// Claude stop_reason values.
+export const CLAUDE_STOP = {
+  END_TURN: "end_turn",
+  MAX_TOKENS: "max_tokens",
+  TOOL_USE: "tool_use",
+  STOP_SEQUENCE: "stop_sequence",
+};
+
+// Gemini finishReason values.
+export const GEMINI_FINISH = {
+  STOP: "STOP",
+  MAX_TOKENS: "MAX_TOKENS",
+  SAFETY: "SAFETY",
+  RECITATION: "RECITATION",
+  BLOCKLIST: "BLOCKLIST",
+  PROHIBITED_CONTENT: "PROHIBITED_CONTENT",
+};

open-sse/translator/schema/index.js

@@ -0,0 +1,8 @@
+// Translator schema barrel — pure data enums (roles, blocks). No logic here.
+export { ROLE, GEMINI_ROLE } from "./roles.js";
+export {
+  OPENAI_BLOCK, CLAUDE_BLOCK, RESPONSES_ITEM,
+  VALID_OPENAI_CONTENT_TYPES, VALID_OPENAI_MESSAGE_TYPES,
+} from "./blocks.js";
+export { OPENAI_FINISH, CLAUDE_STOP, GEMINI_FINISH } from "./finishReasons.js";
+export { MODEL_FALLBACK, DEFAULT_IMAGE_MIME } from "./defaults.js";

open-sse/translator/schema/roles.js

@@ -0,0 +1,16 @@
+// Role enums — fixed per format. Pure data (no logic).
+// OpenAI chat / Claude share these; mapping between them stays in translators.
+
+export const ROLE = {
+  USER: "user",
+  ASSISTANT: "assistant",
+  TOOL: "tool",
+  SYSTEM: "system",
+  DEVELOPER: "developer",
+};
+
+// Gemini / Antigravity use "model" instead of "assistant".
+export const GEMINI_ROLE = {
+  USER: "user",
+  MODEL: "model",
+};