chore: Use primary agent's model as fallback for subagents (#304)

src/agent/model.ts

@@ -68,3 +68,29 @@ export function getModelUpdateArgs(
   const modelInfo = getModelInfo(modelIdentifier);
   return modelInfo?.updateArgs;
 }
+
+/**
+ * Resolve a model ID from the llm_config.model value
+ * The llm_config.model is the model portion without the provider prefix
+ * (e.g., "z-ai/glm-4.6:exacto" for handle "openrouter/z-ai/glm-4.6:exacto")
+ *
+ * Note: This may not distinguish between variants like gpt-5.2-medium vs gpt-5.2-high
+ * since they share the same handle. For provider fallback, this is acceptable.
+ *
+ * @param llmConfigModel - The model value from agent.llm_config.model
+ * @returns The model ID if found, null otherwise
+ */
+export function resolveModelByLlmConfig(llmConfigModel: string): string | null {
+  // Try to find a model whose handle ends with the llm_config model value
+  const match = models.find((m) => m.handle.endsWith(`/${llmConfigModel}`));
+  if (match) return match.id;
+
+  // Also try exact match on the model portion (for simple cases like "gpt-5.2")
+  const exactMatch = models.find((m) => {
+    const parts = m.handle.split("/");
+    return parts.slice(1).join("/") === llmConfigModel;
+  });
+  if (exactMatch) return exactMatch.id;
+
+  return null;
+}

src/agent/subagents/manager.ts

@@ -18,6 +18,9 @@ import { permissionMode } from "../../permissions/mode";
 import { sessionPermissions } from "../../permissions/session";
 import { settingsManager } from "../../settings-manager";
 import { getErrorMessage } from "../../utils/error";
+import { getClient } from "../client";
+import { getCurrentAgentId } from "../context";
+import { resolveModelByLlmConfig } from "../model";
 import { getAllSubagentConfigs, type SubagentConfig } from ".";
 
 // ============================================================================
@@ -50,6 +53,36 @@ interface ExecutionState {
 // Helper Functions
 // ============================================================================
 
+/**
+ * Get the primary agent's model ID
+ * Fetches from API and resolves to a known model ID
+ */
+async function getPrimaryAgentModel(): Promise<string | null> {
+  try {
+    const agentId = getCurrentAgentId();
+    const client = await getClient();
+    const agent = await client.agents.retrieve(agentId);
+    const model = agent.llm_config?.model;
+    if (model) {
+      return resolveModelByLlmConfig(model);
+    }
+    return null;
+  } catch {
+    return null;
+  }
+}
+
+/**
+ * Check if an error message indicates an unsupported provider
+ */
+function isProviderNotSupportedError(errorOutput: string): boolean {
+  return (
+    errorOutput.includes("Provider") &&
+    errorOutput.includes("is not supported") &&
+    errorOutput.includes("supported providers:")
+  );
+}
+
 /**
  * Record a tool call to the state store
  */
@@ -328,7 +361,11 @@ async function executeSubagent(
   userPrompt: string,
   baseURL: string,
   subagentId: string,
+  isRetry = false,
 ): Promise<SubagentResult> {
+  // Update the state with the model being used (may differ on retry/fallback)
+  updateSubagent(subagentId, { model });
+
   try {
     const cliArgs = buildSubagentArgs(type, config, model, userPrompt);
 
@@ -376,6 +413,23 @@ async function executeSubagent(
 
     // Handle non-zero exit code
     if (exitCode !== 0) {
+      // Check if this is a provider-not-supported error and we haven't retried yet
+      if (!isRetry && isProviderNotSupportedError(stderr)) {
+        const primaryModel = await getPrimaryAgentModel();
+        if (primaryModel) {
+          // Retry with the primary agent's model
+          return executeSubagent(
+            type,
+            config,
+            primaryModel,
+            userPrompt,
+            baseURL,
+            subagentId,
+            true, // Mark as retry to prevent infinite loops
+          );
+        }
+      }
+
       return {
         agentId: state.agentId || "",
         report: "",

src/cli/components/SubagentGroupDisplay.tsx

@@ -88,13 +88,14 @@ const AgentRow = memo(({ agent, isLast, expanded }: AgentRowProps) => {
 
   return (
     <Box flexDirection="column">
-      {/* Main row: tree char + description + type + stats */}
+      {/* Main row: tree char + description + type + model + stats */}
       <Box flexDirection="row">
         <Text color={colors.subagent.treeChar}>{treeChar} </Text>
         {getDotElement()}
         <Text> {agent.description}</Text>
         <Text dimColor> · {agent.type.toLowerCase()}</Text>
-        <Text color={colors.subagent.stats}> · {stats}</Text>
+        {agent.model && <Text dimColor> · {agent.model}</Text>}
+        <Text dimColor> · {stats}</Text>
       </Box>
 
       {/* Subagent URL */}

src/cli/components/SubagentGroupStatic.tsx

@@ -31,6 +31,7 @@ export interface StaticSubagent {
   totalTokens: number;
   agentURL: string | null;
   error?: string;
+  model?: string;
 }
 
 interface SubagentGroupStaticProps {
@@ -58,13 +59,14 @@ const AgentRow = memo(({ agent, isLast }: AgentRowProps) => {
 
   return (
     <Box flexDirection="column">
-      {/* Main row: tree char + description + type + stats */}
+      {/* Main row: tree char + description + type + model + stats */}
       <Box flexDirection="row">
         <Text color={colors.subagent.treeChar}>{treeChar} </Text>
         <Text color={dotColor}>●</Text>
         <Text> {agent.description}</Text>
         <Text dimColor> · {agent.type.toLowerCase()}</Text>
-        <Text color={colors.subagent.stats}> · {stats}</Text>
+        {agent.model && <Text dimColor> · {agent.model}</Text>}
+        <Text dimColor> · {stats}</Text>
       </Box>
 
       {/* Subagent URL */}

src/cli/components/colors.ts

@@ -120,7 +120,6 @@ export const colors = {
     completed: brandColors.statusSuccess,
     error: brandColors.statusError,
     treeChar: brandColors.textDisabled,
-    stats: brandColors.textSecondary,
     hint: brandColors.textDisabled,
   },
 

src/cli/helpers/subagentAggregation.ts

@@ -108,6 +108,7 @@ export function createSubagentGroupItem(
         totalTokens: subagent.totalTokens,
         agentURL: subagent.agentURL,
         error: subagent.error,
+        model: subagent.model,
       });
     }
   }

src/cli/helpers/subagentState.ts

@@ -26,6 +26,7 @@ export interface SubagentState {
   totalTokens: number;
   durationMs: number;
   error?: string;
+  model?: string;
   startTime: number;
   toolCallId?: string; // Links this subagent to its parent Task tool call
 }