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style(anthropic-proxy): update comment formatting and add SSE utility functions

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Standardize comment separators and arrow usage in documentation headers.
Additionally, introduce `accumulateSSEText` and `extractTextFromSSE` to
provide robust parsing for various SSE stream formats, including
Claude Code and OpenAI-compatible deltas.
This commit is contained in:
MythEclipse
2026-06-11 01:43:23 +07:00
parent 261f84a96e
commit db065f788d
1 changed files with 123 additions and 34 deletions
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src/lib/anthropic-proxy.ts
+123 -34
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@@ -5,15 +5,15 @@
* and routes them to the same backend AI providers as the OpenAI proxy.
*
* Translations:
* - Anthropic request → backend format (OpenAI-compatible)
* - Backend response → Anthropic Messages format
* - Backend SSE stream → Anthropic SSE events
* - Anthropic request -> backend format (OpenAI-compatible)
* - Backend response -> Anthropic Messages format
* - Backend SSE stream -> Anthropic SSE events
*/
import type { ProxyPool } from "./proxy-pool";
import { MODEL_ROUTES, type BackendConfig } from "./ai-proxy";
// ─── Types ───────────────────────────────────────────────────────────────────────
// --- Types -------------------------------------------------------------------
export interface AnthropicRequest {
model: string;
@@ -40,7 +40,7 @@ interface AnthropicResponse {
usage: { input_tokens: number; output_tokens: number };
}
// ─── Model resolution ─────────────────────────────────────────────────────────
// --- Model resolution ---------------------------------------------------------
/** Resolve a model name to a backend config (uses MODEL_ROUTES directly). */
function resolveAnthropicModel(
@@ -56,7 +56,7 @@ export function listAnthropicModels(): string[] {
return Object.keys(MODEL_ROUTES);
}
// ─── Translation: Anthropic → Backend (OpenAI-format) ───────────────────────
// --- Translation: Anthropic -> Backend (OpenAI-format) -------------------------
interface BackendBody {
model: string;
@@ -123,7 +123,7 @@ function anthropicToBackend(
return base;
}
// ─── Translation: Backend → Anthropic ──────────────────────────────────────
// --- Translation: Backend -> Anthropic ----------------------------------------
/**
* Convert a backend JSON response body into Anthropic Messages format.
@@ -150,7 +150,64 @@ function backendToAnthropicResponse(
};
}
// ─── Streaming: Backend SSE → Anthropic SSE ───────────────────────────────
// --- Streaming: Backend SSE -> Anthropic SSE ---------------------------------
/**
* Accumulate text from an SSE response body (data: lines) into a single string.
* Handles Claude Code SSE format: {"type":"text-delta","delta":"..."}
*/
function accumulateSSEText(sseBody: string): string {
let accumulated = "";
for (const rawLine of sseBody.split("\n")) {
const trimmed = rawLine.trim();
if (!trimmed.startsWith("data: ")) continue;
const raw = trimmed.slice(6);
if (raw === "[DONE]") continue;
try {
const parsed = JSON.parse(raw);
if (parsed.type === "text-delta" && parsed.delta) {
accumulated += parsed.delta;
}
} catch {
// skip unparseable lines
}
}
return accumulated;
}
/**
* Extract text content from a parsed SSE data object regardless of format.
*
* Handles multiple SSE formats:
* - Claude Code format: { "type": "text-delta", "delta": "..." }
* - OpenAI format: { "choices": [{ "delta": { "content": "..." } }] }
* - Generic JSON: { "content": "..." } or { "text": "..." }
*/
function extractTextFromSSE(parsed: any): string | null {
if (parsed == null) return null;
// Claude Code / Anthropic SSE: type-based events
if (typeof parsed === "object") {
switch (parsed.type) {
case "text-delta":
return parsed.delta ?? null;
case "content_block_delta":
return parsed.delta?.text ?? parsed.delta?.delta ?? null;
}
}
// OpenAI format: choices[0].delta.content
const openai = parsed.choices?.[0]?.delta?.content ??
parsed.choices?.[0]?.text;
if (openai) return openai;
// Generic fallbacks
if (typeof parsed.content === "string") return parsed.content;
if (typeof parsed.text === "string") return parsed.text;
if (typeof parsed.delta === "string") return parsed.delta;
return null;
}
/**
* Transform a backend SSE line into Anthropic SSE content_block_delta events.
@@ -171,18 +228,18 @@ function backendLineToAnthropicSSE(
if (adapted === "data: [DONE]") {
return null; // let the stream transformer handle DONE
}
// Parse the OpenAI-format chunk and convert to Anthropic
// Parse the adapted line
try {
const parsed = JSON.parse(adapted.replace(/^data: /, ""));
const text = parsed.choices?.[0]?.delta?.content ?? "";
if (!text) return null;
return formatContentBlockDelta(text);
const text = extractTextFromSSE(parsed);
if (text) return formatContentBlockDelta(text);
return null;
} catch {
return null;
}
}
// OpenAI-compatible SSE (opencode.ai)
// All data: lines -- try to parse as JSON in any format
if (line.startsWith("data: ")) {
const raw = line.slice(6);
if (raw === "[DONE]") {
@@ -190,15 +247,21 @@ function backendLineToAnthropicSSE(
}
try {
const parsed = JSON.parse(raw);
const text = parsed.choices?.[0]?.delta?.content ?? "";
if (!text) return null;
return formatContentBlockDelta(text);
} catch {
// Skip lifecycle/non-content events
if (parsed.type === "start" || parsed.type === "start-step" ||
parsed.type === "data-thinking-step" || parsed.type === "text-start" ||
parsed.type === "ping") {
return null;
}
const text = extractTextFromSSE(parsed);
if (text) return formatContentBlockDelta(text);
return null;
} catch {
// Not JSON -- treat as plain text
}
}
// Plain text chunks
// Plain text chunks (or non-data lines)
if (line.length > 0) {
return formatContentBlockDelta(line);
}
@@ -215,7 +278,7 @@ function formatContentBlockDelta(text: string): string {
})}`;
}
// ─── Stream transformer ────────────────────────────────────────────────────
// --- Stream transformer -------------------------------------------------------
function transformAnthropicStream(
body: ReadableStream,
@@ -229,12 +292,11 @@ function transformAnthropicStream(
// State machine for Anthropic SSE protocol
let phase: "init" | "block" | "done" = "init";
let messageId = `msg_${Date.now()}`;
let _hasContent = false;
return new ReadableStream({
async pull(controller) {
try {
// ── Phase: emit message_start + content_block_start ──────
// --- Phase: emit message_start + content_block_start ------------
if (phase === "init") {
phase = "block";
messageId = `msg_${Date.now()}`;
@@ -255,7 +317,7 @@ function transformAnthropicStream(
})}`;
controller.enqueue(encoder.encode(startEvent + "\n\n"));
// content_block_start — must precede any deltas
// content_block_start -- must precede any deltas
const blockStart = `event: content_block_start\ndata: ${JSON.stringify({
type: "content_block_start",
index: 0,
@@ -264,7 +326,7 @@ function transformAnthropicStream(
controller.enqueue(encoder.encode(blockStart + "\n\n"));
}
// ── Phase: read stream and emit content_block_delta events ─
// --- Phase: read stream and emit content_block_delta events -----
while (phase === "block") {
const { done, value } = await reader.read();
if (done) {
@@ -278,16 +340,15 @@ function transformAnthropicStream(
for (const line of lines) {
const adapted = backendLineToAnthropicSSE(line, model, config);
if (adapted) {
hasContent = true;
controller.enqueue(encoder.encode(adapted + "\n\n"));
}
}
// Yield control so we don't block — let next pull() continue
// Yield control so we don't block -- let next pull() continue
return;
}
// ── Phase: emit closing events (content_block_stop, message_delta, message_stop) ─
// --- Phase: emit closing events (content_block_stop, message_delta, message_stop) -
if (phase === "done") {
phase = "done"; // prevent re-entry
@@ -298,7 +359,7 @@ function transformAnthropicStream(
),
);
// message_delta — required before message_stop
// message_delta -- required before message_stop
controller.enqueue(
encoder.encode(
`event: message_delta\ndata: ${JSON.stringify({
@@ -330,7 +391,7 @@ function transformAnthropicStream(
});
}
// ─── Main handler ─────────────────────────────────────────────────────────
// --- Main handler -------------------------------------------------------------
/**
* Handle an Anthropic-compatible messages request.
@@ -396,7 +457,7 @@ export async function handleAnthropicMessages(
const url = config.url;
// ── Execute (direct → proxy fallback) ─────────────────────────
// ---- Execute (direct -> proxy fallback) --------------------------------
let response: Response | undefined;
for (let attempt = 0; attempt < 3; attempt++) {
@@ -415,18 +476,18 @@ export async function handleAnthropicMessages(
try {
response = await fetch(url, init);
if (response.ok) {
// Success — reset proxy failure if we used one
// Success -- reset proxy failure if we used one
if (proxyPool && proxyPool.size > 0 && init.proxy && attempt > 0) {
proxyPool.markSuccess();
}
break;
}
// Non-2xx — mark proxy as failed so next attempt rotates
// Non-2xx -- mark proxy as failed so next attempt rotates
if (proxyPool && proxyPool.size > 0 && init.proxy) {
proxyPool.markFailed();
}
} catch {
// Network error — mark proxy as failed, retry
// Network error -- mark proxy as failed, retry
if (proxyPool && proxyPool.size > 0 && init.proxy) {
proxyPool.markFailed();
}
@@ -460,7 +521,7 @@ export async function handleAnthropicMessages(
);
}
// ── Handle streaming ─────────────────────────────────────────
// ---- Handle streaming -------------------------------------------------
if (wantsStream) {
const transformed = transformAnthropicStream(
response.body!,
@@ -479,8 +540,36 @@ export async function handleAnthropicMessages(
});
}
// ── Handle non-streaming ─────────────────────────────────────
// ---- Handle non-streaming ---------------------------------------------
const text = await response.text();
// Backend may return SSE (data: lines) even for non-streaming requests.
// Accumulate all text-delta events to reconstruct the response body.
if (text.trimStart().startsWith("data: ")) {
const accumulated = accumulateSSEText(text);
if (accumulated) {
return new Response(
JSON.stringify({
id: `msg_${Date.now()}`,
type: "message",
role: "assistant",
content: [{ type: "text", text: accumulated }],
model: req.model,
stop_reason: "end_turn",
stop_sequence: null,
usage: { input_tokens: 0, output_tokens: 0 },
}),
{
status: 200,
headers: {
"Content-Type": "application/json",
"Access-Control-Allow-Origin": "*",
},
},
);
}
}
let parsed: any;
try {
parsed = JSON.parse(text);