feat: add per-session model selection

src/agents/model-selection.ts

@@ -0,0 +1,75 @@
+import type { ClawdisConfig } from "../config/config.js";
+import type { ModelCatalogEntry } from "./model-catalog.js";
+
+export type ModelRef = {
+  provider: string;
+  model: string;
+};
+
+export function modelKey(provider: string, model: string) {
+  return `${provider}/${model}`;
+}
+
+export function parseModelRef(
+  raw: string,
+  defaultProvider: string,
+): ModelRef | null {
+  const trimmed = raw.trim();
+  if (!trimmed) return null;
+  const slash = trimmed.indexOf("/");
+  if (slash === -1) {
+    return { provider: defaultProvider, model: trimmed };
+  }
+  const provider = trimmed.slice(0, slash).trim();
+  const model = trimmed.slice(slash + 1).trim();
+  if (!provider || !model) return null;
+  return { provider, model };
+}
+
+export function buildAllowedModelSet(params: {
+  cfg: ClawdisConfig;
+  catalog: ModelCatalogEntry[];
+  defaultProvider: string;
+}): {
+  allowAny: boolean;
+  allowedCatalog: ModelCatalogEntry[];
+  allowedKeys: Set<string>;
+} {
+  const rawAllowlist = params.cfg.agent?.allowedModels ?? [];
+  const allowAny = rawAllowlist.length === 0;
+  const catalogKeys = new Set(
+    params.catalog.map((entry) => modelKey(entry.provider, entry.id)),
+  );
+
+  if (allowAny) {
+    return {
+      allowAny: true,
+      allowedCatalog: params.catalog,
+      allowedKeys: catalogKeys,
+    };
+  }
+
+  const allowedKeys = new Set<string>();
+  for (const raw of rawAllowlist) {
+    const parsed = parseModelRef(String(raw), params.defaultProvider);
+    if (!parsed) continue;
+    const key = modelKey(parsed.provider, parsed.model);
+    if (catalogKeys.has(key)) {
+      allowedKeys.add(key);
+    }
+  }
+
+  const allowedCatalog = params.catalog.filter((entry) =>
+    allowedKeys.has(modelKey(entry.provider, entry.id)),
+  );
+
+  if (allowedCatalog.length === 0) {
+    return {
+      allowAny: true,
+      allowedCatalog: params.catalog,
+      allowedKeys: catalogKeys,
+    };
+  }
+
+  return { allowAny: false, allowedCatalog, allowedKeys };
+}