lesson 23 LLM sentence explainer

docs/.vitepress/theme/llm.ts

@@ -0,0 +1,115 @@
+import { fetch } from "@tauri-apps/plugin-http";
+
+//@ts-ignore
+const { VITE_LLM_API_KEY } = import.meta.env;
+
+// Minimal type definitions
+type DeepSeekChunk = {
+  choices: Array<{
+    delta: {
+      content?: string;
+      reasoning_content?: string;
+    };
+  }>;
+};
+
+// Type guard - simple and effective
+function isValidChunk(data: unknown): data is DeepSeekChunk {
+  return (
+    typeof data === "object" &&
+    data !== null &&
+    "choices" in data &&
+    Array.isArray((data as any).choices) &&
+    (data as any).choices.length > 0 &&
+    "delta" in (data as any).choices[0]
+  );
+}
+
+// Helper - one-liner safe parse
+function safeParse<T>(text: string): T | null {
+  try {
+    return JSON.parse(text);
+  } catch {
+    return null;
+  }
+}
+
+export async function* LLMstream(body: {
+  model: string;
+  messages: {
+    role: "system" | "user";
+    content: string;
+  }[];
+}) {
+  if (!VITE_LLM_API_KEY) return;
+
+  let endpoint = "https://api.deepseek.com/chat/completions";
+
+  const response = await fetch(endpoint, {
+    method: "POST",
+    headers: {
+      Authorization: `Bearer ${VITE_LLM_API_KEY}`,
+      "Content-Type": "application/json",
+    },
+    body: JSON.stringify({
+      ...body,
+      stream: true,
+    }),
+  });
+
+  if (!response.ok || !response.body) {
+    throw response;
+  }
+
+  const reader = response.body.pipeThrough(new TextDecoderStream()).getReader();
+
+  let buffer = "";
+
+  while (true) {
+    const { value, done } = await reader.read();
+    if (done) break;
+
+    buffer += value;
+
+    const events = buffer.split("\n\n");
+    buffer = events.pop() || "";
+
+    for (const event of events) {
+      for (const line of event.split("\n")) {
+        const DATA_START = "data: ";
+
+        if (!line.startsWith(DATA_START)) continue;
+        const payload = line.slice(DATA_START.length);
+
+        if (payload === "[DONE]") {
+          yield { content: "", done: true };
+          return;
+        }
+
+        const chunk = safeParse<DeepSeekChunk>(payload);
+
+        if (!chunk?.choices?.[0]?.delta) continue;
+
+        const delta = chunk.choices[0].delta;
+
+        // Yield content if present
+        if (delta.content) {
+          yield {
+            content: delta.content,
+            reasoning: delta.reasoning_content,
+            done: false,
+          };
+        }
+
+        // Yield reasoning separately if present and no content
+        if (delta.reasoning_content && !delta.content) {
+          yield {
+            content: "",
+            reasoning: delta.reasoning_content,
+            done: false,
+          };
+        }
+      }
+    }
+  }
+}