initial commit

packages/backend/src/agents/ranking.ts

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+import { openai } from '../agent.js';
+import type { InterpreterOutput, RetrievalOutput, RankingOutput } from '../types/agents.js';
+
+export async function runRanking(
+  interpreter: InterpreterOutput,
+  retrieval: RetrievalOutput,
+): Promise<RankingOutput> {
+  // Phase 1: Pre-filter — remove avoidance violations
+  const avoidList = interpreter.avoid.map((a) => a.toLowerCase());
+  const filtered = retrieval.candidates.filter((c) => {
+    const text = (c.title + ' ' + c.reason).toLowerCase();
+    return !avoidList.some((a) => text.includes(a));
+  });
+
+  // Phase 2: Chunked ranking — split into groups of ~15
+  const CHUNK_SIZE = 15;
+  const chunks: typeof filtered[] = [];
+  for (let i = 0; i < filtered.length; i += CHUNK_SIZE) {
+    chunks.push(filtered.slice(i, i + CHUNK_SIZE));
+  }
+
+  const allBuckets: RankingOutput = {
+    definitely_like: [],
+    might_like: [],
+    questionable: [],
+    will_not_like: [],
+  };
+
+  for (const chunk of chunks) {
+    const chunkTitles = chunk.map((c) => `- ${c.title}: ${c.reason}`).join('\n');
+
+    const response = await openai.chat.completions.create({
+      model: 'gpt-5.4',
+      temperature: 0.2,
+      service_tier: 'flex',
+      response_format: { type: 'json_object' },
+      messages: [
+        {
+          role: 'system',
+          content: `You are a TV show ranking critic. Assign each show to exactly one of four confidence buckets based on how well it matches the user's preferences.
+
+Buckets:
+- "definitely_like": Near-perfect match to all preferences
+- "might_like": Strong match to most preferences
+- "questionable": Partial alignment, some aspects don't match
+- "will_not_like": Likely mismatch, conflicts with preferences or avoidance criteria
+
+Your output MUST be valid JSON:
+{
+  "definitely_like": string[],
+  "might_like": string[],
+  "questionable": string[],
+  "will_not_like": string[]
+}
+
+Every show in the input must appear in exactly one bucket. Use the title exactly as given.`,
+        },
+        {
+          role: 'user',
+          content: `User preferences:
+Liked shows: ${JSON.stringify(interpreter.liked)}
+Themes: ${JSON.stringify(interpreter.themes)}
+Character preferences: ${JSON.stringify(interpreter.character_preferences)}
+Tone: ${JSON.stringify(interpreter.tone)}
+Avoid: ${JSON.stringify(interpreter.avoid)}
+
+Rank these shows:
+${chunkTitles}`,
+        },
+      ],
+    });
+
+    const content = response.choices[0]?.message?.content ?? '{}';
+    const chunkResult = JSON.parse(content) as Partial<RankingOutput>;
+
+    allBuckets.definitely_like.push(...(chunkResult.definitely_like ?? []));
+    allBuckets.might_like.push(...(chunkResult.might_like ?? []));
+    allBuckets.questionable.push(...(chunkResult.questionable ?? []));
+    allBuckets.will_not_like.push(...(chunkResult.will_not_like ?? []));
+  }
+
+  return allBuckets;
+}