feat(antigravity): add model specs and update mapping logic

src/lib/antigravity/ModelSpecs.ts

@@ -0,0 +1,40 @@
+import modelSpecsJson from './model-specs';
+
+type ModelSpec = {
+  max_output_tokens?: number;
+  thinking_budget?: number;
+  is_thinking?: boolean;
+};
+
+type SpecsConfig = {
+  models: Record<string, ModelSpec>;
+  aliases: Record<string, string>;
+};
+
+const DEFAULT_MAX_OUTPUT_TOKENS = 65535;
+const DEFAULT_THINKING_BUDGET = 24576;
+
+const SPECS = modelSpecsJson as SpecsConfig;
+
+export function resolveModelAlias(modelId: string): string {
+  const normalized = modelId.trim();
+  return SPECS.aliases[normalized] ?? normalized;
+}
+
+export function getMaxOutputTokens(modelId: string): number {
+  const resolved = resolveModelAlias(modelId);
+  const fromSpec = SPECS.models[resolved]?.max_output_tokens;
+  if (typeof fromSpec === 'number' && Number.isFinite(fromSpec) && fromSpec > 0) {
+    return Math.floor(fromSpec);
+  }
+  return DEFAULT_MAX_OUTPUT_TOKENS;
+}
+
+export function getThinkingBudget(modelId: string): number {
+  const resolved = resolveModelAlias(modelId);
+  const fromSpec = SPECS.models[resolved]?.thinking_budget;
+  if (typeof fromSpec === 'number' && Number.isFinite(fromSpec) && fromSpec >= 0) {
+    return Math.floor(fromSpec);
+  }
+  return DEFAULT_THINKING_BUDGET;
+}