feat(FN-4080): complete Step 1 — add thinking persistence resolver

Fusion-Task-Id: FN-4080
Fusion-Task-Lineage: 086863ba-7100-41ab-9cfc-197301fbcab0

packages/core/src/settings-schema.ts

@@ -87,6 +87,8 @@ export const DEFAULT_GLOBAL_SETTINGS = {
   vitestKillThresholdPct: 90,
   // Agent log persistence controls
   persistAgentToolOutput: true,
+  persistAgentThinkingLogPermanent: false,
+  persistAgentThinkingLogEphemeral: false,
   persistAgentThinkingLog: false,
   researchGlobalDefaults: {
     searchProvider: undefined,
@@ -363,3 +365,16 @@ export function isProjectSettingsKey(key: string): key is keyof ProjectSettings
 export function isGlobalOnlySettingsKey(key: string): key is keyof GlobalSettings {
   return isGlobalSettingsKey(key) && !isProjectSettingsKey(key);
 }
+
+export function resolvePersistAgentThinkingLog(
+  settings: Partial<GlobalSettings> | undefined,
+  opts: { ephemeral: boolean },
+): boolean {
+  const granular = opts.ephemeral
+    ? settings?.persistAgentThinkingLogEphemeral
+    : settings?.persistAgentThinkingLogPermanent;
+
+  if (typeof granular === "boolean") return granular;
+  if (typeof settings?.persistAgentThinkingLog === "boolean") return settings.persistAgentThinkingLog;
+  return false;
+}