Initial commit: StudyOS platform

server/lib/llm.js

@@ -0,0 +1,91 @@
+const Anthropic = require('@anthropic-ai/sdk');
+const OpenAI = require('openai');
+
+/**
+ * Normalize Anthropic + OpenAI-compatible streams into one AsyncIterable.
+ * Yields: { token, done, fullText } events.
+ * Handles errors gracefully — emits error event, doesn't crash.
+ *
+ * Usage:
+ *   for await (const chunk of streamCompletion(model, messages, systemPrompt)) {
+ *     // chunk = { token: string, done: boolean, fullText: string }
+ *   }
+ */
+async function* streamCompletion(model, messages, systemPrompt) {
+  if (!model || !model.provider) {
+    yield { token: '', done: true, fullText: '', error: 'Model or provider not specified' };
+    return;
+  }
+
+  try {
+    if (model.provider === 'anthropic') {
+      yield* streamAnthropic(model, messages, systemPrompt);
+    } else if (model.provider === 'openai') {
+      yield* streamOpenAI(model, messages, systemPrompt);
+    } else {
+      yield { token: '', done: true, fullText: '', error: `Unknown provider: ${model.provider}` };
+    }
+  } catch (err) {
+    console.error('[llm] streamCompletion error:', err.message);
+    yield { token: '', done: true, fullText: '', error: err.message };
+  }
+}
+
+async function* streamAnthropic(model, messages, systemPrompt) {
+  const client = new Anthropic({
+    apiKey: model.api_key || process.env.ANTHROPIC_API_KEY,
+  });
+
+  const stream = await client.messages.create({
+    model: model.name,
+    max_tokens: 4096,
+    system: systemPrompt || undefined,
+    messages: messages.map(m => ({ role: m.role, content: m.content })),
+    stream: true,
+  });
+
+  let fullText = '';
+
+  for await (const event of stream) {
+    if (event.type === 'content_block_delta' && event.delta?.type === 'text_delta') {
+      const token = event.delta.text || '';
+      fullText += token;
+      yield { token, done: false, fullText };
+    }
+  }
+
+  yield { token: '', done: true, fullText };
+}
+
+async function* streamOpenAI(model, messages, systemPrompt) {
+  const client = new OpenAI({
+    apiKey: model.api_key || process.env.OPENAI_API_KEY,
+    baseURL: model.api_base,
+  });
+
+  const openaiMessages = [];
+  if (systemPrompt) {
+    openaiMessages.push({ role: 'system', content: systemPrompt });
+  }
+  openaiMessages.push(...messages.map(m => ({ role: m.role, content: m.content })));
+
+  const stream = await client.chat.completions.create({
+    model: model.name,
+    messages: openaiMessages,
+    stream: true,
+  });
+
+  let fullText = '';
+
+  for await (const chunk of stream) {
+    const token = chunk.choices?.[0]?.delta?.content || '';
+    if (token) {
+      fullText += token;
+      yield { token, done: false, fullText };
+    }
+  }
+
+  yield { token: '', done: true, fullText };
+}
+
+module.exports = { streamCompletion };