feat(subagents): add per-agent model overrides

crates/agent-gui/src/lib/subagents/agentTool.ts

@@ -40,12 +40,28 @@ import type { SubagentConversationStore } from "./store";
 import {
   AGENT_TOOL_NAME,
   MAX_AGENTS,
+  type SubagentModelSelection,
   type SubagentTemplate,
   type SubagentToolRegistry,
 } from "./types";
 import { createSequentialQueue, normalizeErrorMessage, runWithConcurrency } from "./utils";
 import { parseSubagentBatch, type ResolvedSubagentSpec } from "./validate";
 
+const MODEL_SELECTION_PARAMETER = Type.Object(
+  {
+    custom_provider_id: Type.String({
+      minLength: 1,
+      description: "Configured provider id from LiveAgent settings.",
+    }),
+    model: Type.String({ minLength: 1, description: "Enabled model id for that provider." }),
+  },
+  {
+    additionalProperties: false,
+    description:
+      "Optional model override for this run. Omit it to inherit the parent conversation model.",
+  },
+);
+
 const AGENT_PARAMETERS = Type.Object(
   {
     agents: Type.Array(
@@ -80,6 +96,7 @@ const AGENT_PARAMETERS = Type.Object(
                 "Enabled AGENTS template id or name. Only valid when the id is first created.",
             }),
           ),
+          model: Type.Optional(MODEL_SELECTION_PARAMETER),
           mode: Type.Optional(
             Type.Union([Type.Literal("readonly"), Type.Literal("worktree")], {
               description:
@@ -185,16 +202,28 @@ export type SubagentRuntimeConfig = {
   providerId: ProviderId;
   model: string;
   runtime: SubagentProviderRuntime;
+  resolveModel?: ResolveSubagentModel;
   sessionId?: string;
   templates: SubagentTemplate[];
   store: SubagentConversationStore;
   scheduler: SubagentScheduler;
 };
 
+export type ResolvedSubagentModel = {
+  providerId: ProviderId;
+  model: string;
+  runtime: SubagentProviderRuntime;
+};
+
+export type ResolveSubagentModel = (
+  selectedModel: SubagentModelSelection,
+) => ResolvedSubagentModel | undefined;
+
 export function createSubagentTools(params: {
   providerId: ProviderId;
   model: string;
   runtime: SubagentProviderRuntime;
+  resolveModel?: ResolveSubagentModel;
   runtimePlatform?: RuntimePlatform;
   workdir: string;
   resolveHomeDir?: () => Promise<string>;
@@ -292,6 +321,41 @@ export function createSubagentTools(params: {
     if (!parsed.ok) {
       return rejectBatch(parsed.issues);
     }
+    const modelByAgentId = new Map<string, ResolvedSubagentModel>();
+    const modelIssues: SubagentIssue[] = [];
+    for (const agent of parsed.batch.agents) {
+      const selectedModel = agent.spec.selectedModel;
+      if (!selectedModel) continue;
+
+      let resolvedModel: ResolvedSubagentModel | undefined;
+      try {
+        resolvedModel = params.resolveModel?.(selectedModel);
+      } catch (error) {
+        modelIssues.push(
+          issue(
+            "model_unavailable",
+            `Configured model ${selectedModel.customProviderId}/${selectedModel.model} could not be resolved: ${normalizeErrorMessage(error, "unknown model configuration error")}`,
+            agent.spec.id,
+          ),
+        );
+        continue;
+      }
+      if (!resolvedModel) {
+        modelIssues.push(
+          issue(
+            "model_unavailable",
+            `Configured model ${selectedModel.customProviderId}/${selectedModel.model} is missing or disabled. Select an active model or omit the override to inherit the conversation model.`,
+            agent.spec.id,
+          ),
+        );
+        continue;
+      }
+      modelByAgentId.set(agent.spec.id, resolvedModel);
+    }
+    if (modelIssues.length > 0) {
+      return rejectBatch(modelIssues);
+    }
+
     const { agents, issues: pathIssues } = await resolveOutputPaths({
       agents: parsed.batch.agents,
       workdir: params.workdir,
@@ -380,10 +444,19 @@ export function createSubagentTools(params: {
         };
 
         try {
+          const resolvedModel = modelByAgentId.get(resolved.spec.id);
+          const runEnvironment = resolvedModel
+            ? {
+                ...env,
+                providerId: resolvedModel.providerId,
+                model: resolvedModel.model,
+                runtime: resolvedModel.runtime,
+              }
+            : env;
           const report = await enqueueAgentRun(resolved.spec.id, () =>
             scheduler.runSubagent(
               () =>
-                executeSubagentRun(env, {
+                executeSubagentRun(runEnvironment, {
                   spec: resolved.spec,
                   existingIdentity: resolved.existingIdentity,
                   template: resolved.template,

crates/agent-gui/src/lib/subagents/errors.ts

@@ -13,6 +13,7 @@ export type SubagentIssueCode =
   | "unknown_agent_id"
   | "unknown_template"
   | "identity_conflict"
+  | "model_unavailable"
   | "worktree_unavailable"
   | "output_path_outside_workspace"
   | "unknown_recipient"

crates/agent-gui/src/lib/subagents/index.ts

@@ -1,4 +1,9 @@
-export { createSubagentTools, type SubagentRuntimeConfig } from "./agentTool";
+export {
+  createSubagentTools,
+  type ResolvedSubagentModel,
+  type ResolveSubagentModel,
+  type SubagentRuntimeConfig,
+} from "./agentTool";
 export { renderMessageBusSnapshot } from "./bus";
 export { isSubagentCardToolCall } from "./card";
 export type { SubagentStoreIpc } from "./ipc/store";
@@ -33,6 +38,7 @@ export {
   SUBAGENT_BROADCAST_RECIPIENT,
   SUBAGENT_PARENT_ID,
   type SubagentIdentity,
+  type SubagentModelSelection,
   type SubagentRunSummary,
   type SubagentTemplate,
   type SubagentToolRegistry,

crates/agent-gui/src/lib/subagents/policy.ts

@@ -236,7 +236,7 @@ export function decideWorktreeCleanup(params: {
   return { shouldCleanup: false, reason: "unapplied_changes" };
 }
 
-/** Readonly children: read-only builtin tools + MCP business tools. */
+/** Readonly children: only tools whose metadata explicitly declares read-only behavior. */
 export function selectReadOnlyTools(params: {
   tools: Tool[];
   metadataByName: Map<string, ToolMetadataLike>;
@@ -245,9 +245,7 @@ export function selectReadOnlyTools(params: {
     if (tool.name === AGENT_TOOL_NAME) return false;
     if (tool.name === SEND_MESSAGE_TOOL_NAME) return true;
     const metadata = params.metadataByName.get(tool.name);
-    return (
-      metadata?.isReadOnly === true || (metadata?.groupId === "mcp" && metadata.kind === "mcp")
-    );
+    return metadata?.isReadOnly === true;
   });
 }
 

crates/agent-gui/src/lib/subagents/types.ts

@@ -24,6 +24,11 @@ export type SubagentApplyPolicy = "none" | "explicit" | "auto";
 export type SubagentRunStatus = "running" | "completed" | "failed" | "cancelled";
 export type SubagentMessageChannel = "direct" | "shared" | "decision" | "question";
 
+export type SubagentModelSelection = {
+  customProviderId: string;
+  model: string;
+};
+
 /** One fully validated agent request inside an Agent tool call. */
 export type SubagentSpec = {
   id: string;
@@ -32,6 +37,7 @@ export type SubagentSpec = {
   role?: string;
   identity?: string;
   templateId?: string;
+  selectedModel?: SubagentModelSelection;
   mode: SubagentMode;
   applyPolicy: SubagentApplyPolicy;
   allowedOutputPaths: string[];

crates/agent-gui/src/lib/subagents/validate.ts

@@ -8,6 +8,7 @@ import {
   type SubagentApplyPolicy,
   type SubagentIdentity,
   type SubagentMode,
+  type SubagentModelSelection,
   type SubagentSpec,
   type SubagentTemplate,
 } from "./types";
@@ -48,6 +49,7 @@ const KNOWN_AGENT_KEYS = new Set([
   "role",
   "identity",
   "template",
+  "model",
   "mode",
   "apply_policy",
   "allowed_output_paths",
@@ -58,6 +60,51 @@ const KNOWN_AGENT_KEYS = new Set([
 const MODES = new Set<SubagentMode>(["readonly", "worktree"]);
 const APPLY_POLICIES = new Set<SubagentApplyPolicy>(["none", "explicit", "auto"]);
 
+function parseModelSelection(
+  value: unknown,
+  agentId: string | undefined,
+  issues: SubagentIssue[],
+): SubagentModelSelection | undefined {
+  if (typeof value === "undefined") return undefined;
+  if (!value || typeof value !== "object" || Array.isArray(value)) {
+    issues.push(
+      issue(
+        "invalid_arguments",
+        "model must be an object with custom_provider_id and model strings.",
+        agentId,
+      ),
+    );
+    return undefined;
+  }
+
+  const obj = asObject(value);
+  for (const key of Object.keys(obj)) {
+    if (key !== "custom_provider_id" && key !== "model") {
+      issues.push(
+        issue(
+          "invalid_arguments",
+          `Unknown model field "${key}". Allowed fields: custom_provider_id, model.`,
+          agentId,
+        ),
+      );
+    }
+  }
+
+  const customProviderId = optionalString(obj.custom_provider_id);
+  const model = optionalString(obj.model);
+  if (!customProviderId || !model) {
+    issues.push(
+      issue(
+        "invalid_arguments",
+        "model.custom_provider_id and model.model must both be non-empty strings.",
+        agentId,
+      ),
+    );
+    return undefined;
+  }
+  return { customProviderId, model };
+}
+
 function parseOptionalBoolean(
   value: unknown,
   field: string,
@@ -233,6 +280,7 @@ export function parseSubagentBatch(
     const role = optionalString(entry.role);
     const identityText = optionalString(entry.identity);
     const templateRef = optionalString(entry.template);
+    const selectedModel = parseModelSelection(entry.model, agentRef, issues);
 
     let template: SubagentTemplate | undefined;
     if (templateRef) {
@@ -343,6 +391,7 @@ export function parseSubagentBatch(
         role,
         identity: identityText,
         templateId: template?.id ?? existingIdentity?.templateId,
+        selectedModel,
         mode,
         applyPolicy,
         allowedOutputPaths,

crates/agent-gui/src/lib/tools/builtinRegistry.ts

@@ -290,6 +290,7 @@ export async function buildBuiltinToolRegistry(
       providerId: subagentRuntime.providerId,
       model: subagentRuntime.model,
       runtime: subagentRuntime.runtime,
+      resolveModel: subagentRuntime.resolveModel,
       runtimePlatform: params.runtimePlatform,
       workdir: params.workdir,
       resolveHomeDir,

crates/agent-gui/src/pages/ChatPage.tsx

@@ -173,6 +173,7 @@ import {
   collectRetainedSubagentParentToolCallIds,
   createSubagentStoreManager,
   pruneSubagentRunsForConversation,
+  type ResolveSubagentModel,
 } from "../lib/subagents";
 import {
   applyTerminalEventToSessions,
@@ -572,6 +573,23 @@ function buildProviderRuntimeConfig(
   };
 }
 
+function createSubagentModelResolver(
+  settings: AppSettings,
+  runtimeControls: ChatRuntimeControls,
+): ResolveSubagentModel {
+  return (selectedModel) => {
+    const provider = settings.customProviders.find(
+      (item) => item.id === selectedModel.customProviderId,
+    );
+    if (!provider?.activeModels.includes(selectedModel.model)) return undefined;
+    return {
+      providerId: provider.type,
+      model: selectedModel.model,
+      runtime: buildProviderRuntimeConfig(provider, selectedModel.model, runtimeControls),
+    };
+  };
+}
+
 function selectedModelsMatch(left: SelectedModel | undefined, right: SelectedModel | undefined) {
   return (
     Boolean(left) &&
@@ -3780,6 +3798,7 @@ export function ChatPage(props: ChatPageProps) {
       overrides?.runtimeControlsOverride ??
       settings.chatRuntimeControls;
     const providerConfig = buildProviderRuntimeConfig(provider, model, runtimeControls);
+    const resolveSubagentModel = createSubagentModelResolver(settings, runtimeControls);
     const memorySummaryModelSelection = resolveMemorySummaryModelSelection(settings);
     const memoryExtractionModel = memorySummaryModelSelection
       ? {
@@ -4508,6 +4527,7 @@ export function ChatPage(props: ChatPageProps) {
             },
             runtimeModel,
             selectedModel,
+            resolveSubagentModel,
             memoryExtractionModel,
             onMemoryExtractionModelFailure: handleMemoryExtractionModelFailure,
             memoryExtractionStatusText,

crates/agent-gui/src/pages/chat/turns/runAgentConversationTurn.ts

@@ -58,6 +58,7 @@ import {
   buildRosterReminder,
   createSubagentScheduler,
   isSubagentCardToolCall,
+  type ResolveSubagentModel,
   renderMessageBusSnapshot,
   SUBAGENT_PARENT_ID,
   type SubagentConversationStore,
@@ -206,6 +207,7 @@ export type RunAgentConversationTurnParams = {
     customProviderId: string;
     model: string;
   };
+  resolveSubagentModel: ResolveSubagentModel;
   effectiveWorkdir: string;
   effectiveSkillsEnabled: boolean;
   showSilentMemoryExtraction: boolean;
@@ -275,6 +277,7 @@ export async function runAgentConversationTurn(params: RunAgentConversationTurnP
     runtime,
     runtimeModel,
     selectedModel,
+    resolveSubagentModel,
     effectiveWorkdir,
     effectiveSkillsEnabled,
     showSilentMemoryExtraction,
@@ -422,6 +425,7 @@ export async function runAgentConversationTurn(params: RunAgentConversationTurnP
           providerId,
           model,
           runtime,
+          resolveModel: resolveSubagentModel,
           sessionId,
           templates: enabledSubagentTemplates(agentTemplates),
           store: subagentStore,