refactor(agents): centralize model fallback resolution

src/agents/agent-scope.ts

@@ -7,6 +7,7 @@ import {
   DEFAULT_AGENT_ID,
   normalizeAgentId,
   parseAgentSessionKey,
+  resolveAgentIdFromSessionKey,
 } from "../routing/session-key.js";
 import { resolveUserPath } from "../utils.js";
 import { normalizeSkillFilter } from "./skills/filter.js";
@@ -19,7 +20,7 @@ function stripNullBytes(s: string): string {
   return s.replace(/\0/g, "");
 }
 
-export { resolveAgentIdFromSessionKey } from "../routing/session-key.js";
+export { resolveAgentIdFromSessionKey };
 
 type AgentEntry = NonNullable<NonNullable<OpenClawConfig["agents"]>["list"]>[number];
 
@@ -203,6 +204,41 @@ export function resolveAgentModelFallbacksOverride(
   return Array.isArray(raw.fallbacks) ? raw.fallbacks : undefined;
 }
 
+export function resolveFallbackAgentId(params: {
+  agentId?: string | null;
+  sessionKey?: string | null;
+}): string {
+  const explicitAgentId = typeof params.agentId === "string" ? params.agentId.trim() : "";
+  if (explicitAgentId) {
+    return normalizeAgentId(explicitAgentId);
+  }
+  return resolveAgentIdFromSessionKey(params.sessionKey);
+}
+
+export function resolveRunModelFallbacksOverride(params: {
+  cfg: OpenClawConfig | undefined;
+  agentId?: string | null;
+  sessionKey?: string | null;
+}): string[] | undefined {
+  if (!params.cfg) {
+    return undefined;
+  }
+  return resolveAgentModelFallbacksOverride(
+    params.cfg,
+    resolveFallbackAgentId({ agentId: params.agentId, sessionKey: params.sessionKey }),
+  );
+}
+
+export function hasConfiguredModelFallbacks(params: {
+  cfg: OpenClawConfig | undefined;
+  agentId?: string | null;
+  sessionKey?: string | null;
+}): boolean {
+  const fallbacksOverride = resolveRunModelFallbacksOverride(params);
+  const defaultFallbacks = resolveAgentModelFallbackValues(params.cfg?.agents?.defaults?.model);
+  return (fallbacksOverride ?? defaultFallbacks).length > 0;
+}
+
 export function resolveEffectiveModelFallbacks(params: {
   cfg: OpenClawConfig;
   agentId: string;