wehub-resource-sync
80 lines
3.2 KiB
TypeScript
80 lines
3.2 KiB
TypeScript
/**
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* #1311: echo the client-requested model/alias name back in the response.
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*
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* When a request uses an alias or combo (e.g. `claude-sonnet-cx` → `cx/gpt-5.5`),
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* OmniRoute forwards the upstream model name (`gpt-5.5`) in the response `model`
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* field. Strict clients (e.g. Claude Desktop) validate that the response model
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* matches the request and reject the mismatch with a 401. This opt-in helper
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* rewrites the `model` field back to the name the client asked for.
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*
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* The behavior is gated by a global setting (`echoRequestedModelName`, default off),
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* so the default response stays byte-for-byte unchanged.
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*/
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/**
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* Rewrite the top-level `model` field of a parsed response object (Chat Completions
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* JSON or an OpenAI SSE chunk) to `echoModel`. Mutates and returns `obj`. No-op when
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* `echoModel` is falsy or `obj` has no string `model` field.
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*/
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export function echoModelInObject(obj: unknown, echoModel: string | null | undefined): unknown {
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if (!echoModel) return obj;
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if (obj && typeof obj === "object" && !Array.isArray(obj)) {
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const rec = obj as Record<string, unknown>;
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if (typeof rec.model === "string") {
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rec.model = echoModel;
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}
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}
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return obj;
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}
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/**
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* Rewrite the `model` field inside a single SSE line. Only `data: {json}` lines that
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* carry a string `model` are rewritten; `data: [DONE]`, comments, event lines, and
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* unparseable payloads pass through untouched.
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*/
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export function echoModelInSseLine(line: string, echoModel: string | null | undefined): string {
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if (!echoModel) return line;
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if (!line.startsWith("data:")) return line;
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const payload = line.slice(5).trim();
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if (!payload || payload === "[DONE]" || payload[0] !== "{") return line;
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try {
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const parsed = JSON.parse(payload) as Record<string, unknown>;
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if (typeof parsed.model !== "string") return line;
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parsed.model = echoModel;
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return `data: ${JSON.stringify(parsed)}`;
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} catch {
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return line;
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}
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}
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/**
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* A TransformStream that rewrites the `model` field in every SSE `data:` chunk of a
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* UTF-8 byte stream to `echoModel`. Buffers across chunk boundaries so a `data:` frame
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* split across two reads is still rewritten correctly. Used as the final pipe stage of
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* the streaming response when the echo setting is on.
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*/
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export function createModelEchoTransform(echoModel: string | null | undefined): TransformStream {
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const decoder = new TextDecoder();
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const encoder = new TextEncoder();
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let buffer = "";
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return new TransformStream({
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transform(chunk, controller) {
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buffer += decoder.decode(chunk, { stream: true });
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// Emit complete lines; keep the trailing partial line in the buffer.
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const lastNewline = buffer.lastIndexOf("\n");
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if (lastNewline === -1) return;
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const ready = buffer.slice(0, lastNewline + 1);
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buffer = buffer.slice(lastNewline + 1);
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const rewritten = ready
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.split("\n")
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.map((line) => echoModelInSseLine(line, echoModel))
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.join("\n");
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controller.enqueue(encoder.encode(rewritten));
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},
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flush(controller) {
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const tail = buffer + decoder.decode();
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if (tail) controller.enqueue(encoder.encode(echoModelInSseLine(tail, echoModel)));
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},
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});
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}
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