feat(ai): single-shot note polishing for logged work entries

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/lib/ai/polish.ts

@@ -0,0 +1,39 @@
+import "server-only";
+
+import { getProvider, getSystemPrompt, AiError } from "@/lib/ai";
+
+/** Longer than this and the model has ignored the "one or two sentences" instruction. */
+const MAX_POLISHED_LENGTH = 600;
+
+/**
+ * Rewrite a single owner-typed note in the same voice as a commit summary.
+ *
+ * Unlike summarise.ts's summariseProject, this is not batch- or DB-coupled —
+ * it is one piece of text being composed interactively in a form, so it is
+ * one direct provider call rather than the pending-rows pipeline built for
+ * re-summarizing hundreds of ingested commits at once.
+ */
+export async function polishNote(text: string): Promise<string> {
+  const provider = await getProvider();
+  const system = await getSystemPrompt();
+
+  const result = await provider.complete({
+    system,
+    user: `Rewrite the note below as one or two plain-English sentences for the client, in the same voice you use for commit summaries. Stay grounded in exactly what is written — do not invent detail, dates, or claims of completion beyond what the note itself says. Reply with only the rewritten text, nothing else.
+
+Note:
+${text.trim()}`,
+    // 16k, not a number that looks sufficient for two sentences — see the
+    // note in summarise.ts about MiniMax's inline reasoning being billed
+    // against max_tokens. A too-low cap here would silently return an
+    // empty string with no error, exactly as it did for commit summaries.
+    maxTokens: 16384,
+  });
+
+  const polished = result.text.trim();
+  if (!polished) {
+    throw new AiError("The assistant returned nothing usable", true);
+  }
+
+  return polished.slice(0, MAX_POLISHED_LENGTH);
+}