feat(ai): settings storage with a browser-safe projection

src/lib/ai/settings.ts

@@ -0,0 +1,114 @@
+import "server-only";
+
+import { getAdminPb } from "@/lib/pb/admin";
+import type { ProviderName } from "@/lib/ai/types";
+
+/**
+ * Reads and writes the single `settings` record created in Phase 1.
+ *
+ * Superuser-only, always. `ai_api_key` is a live credential and every rule on
+ * that collection is null for exactly that reason — no browser, the owner's
+ * included, may fetch it. Nothing here may be called from a client component.
+ */
+
+export interface AiSettings {
+  provider: ProviderName;
+  apiKey: string;
+  model: string;
+  systemPromptExtra: string;
+}
+
+/** Safe to send to a browser: presence of a key, never its value. */
+export interface AiSettingsView {
+  provider: ProviderName;
+  hasApiKey: boolean;
+  model: string;
+  systemPromptExtra: string;
+}
+
+export const DEFAULT_MODELS: Record<ProviderName, string> = {
+  // Verified against the bundled claude-api skill, not recalled. The whole
+  // 779-commit backfill costs well under a dollar on this model, so there is no
+  // cost argument for a weaker default.
+  anthropic: "claude-opus-5",
+  minimax: "MiniMax-M2",
+  openai: "gpt-4o-mini",
+};
+
+async function settingsRecord() {
+  const pb = await getAdminPb();
+  const existing = await pb
+    .collection("settings")
+    .getFirstListItem("id != ''")
+    .catch(() => null);
+  return { pb, existing };
+}
+
+export async function loadAiSettings(): Promise<AiSettings | null> {
+  const { existing } = await settingsRecord();
+  if (!existing) return null;
+
+  const provider = (existing.ai_provider || "anthropic") as ProviderName;
+
+  return {
+    provider,
+    apiKey: existing.ai_api_key || "",
+    model: existing.ai_model || DEFAULT_MODELS[provider],
+    systemPromptExtra: existing.ai_system_prompt_extra || "",
+  };
+}
+
+/** The browser-safe projection. Never returns the key itself. */
+export async function loadAiSettingsView(): Promise<AiSettingsView> {
+  const settings = await loadAiSettings();
+  if (!settings) {
+    return {
+      provider: "anthropic",
+      hasApiKey: false,
+      model: DEFAULT_MODELS.anthropic,
+      systemPromptExtra: "",
+    };
+  }
+
+  return {
+    provider: settings.provider,
+    hasApiKey: Boolean(settings.apiKey),
+    model: settings.model,
+    systemPromptExtra: settings.systemPromptExtra,
+  };
+}
+
+/**
+ * Write settings, creating the record on first save.
+ *
+ * `apiKey` is only written when a non-empty value is supplied. The settings
+ * form submits an empty key field when the owner is editing something else, and
+ * treating that as "clear the key" would silently disable the whole feature.
+ */
+export async function saveAiSettings(patch: {
+  provider?: ProviderName;
+  apiKey?: string;
+  model?: string;
+  systemPromptExtra?: string;
+}): Promise<void> {
+  const { pb, existing } = await settingsRecord();
+
+  const data: Record<string, unknown> = {};
+  if (patch.provider !== undefined) data.ai_provider = patch.provider;
+  if (patch.model !== undefined) data.ai_model = patch.model.trim();
+  if (patch.systemPromptExtra !== undefined) {
+    data.ai_system_prompt_extra = patch.systemPromptExtra;
+  }
+  if (patch.apiKey) data.ai_api_key = patch.apiKey.trim();
+
+  if (existing) {
+    await pb.collection("settings").update(existing.id, data);
+  } else {
+    await pb.collection("settings").create(data);
+  }
+}
+
+export async function aiConfigured(): Promise<boolean> {
+  const settings = await loadAiSettings();
+  return Boolean(settings?.apiKey);
+}