feat(coding-agent/task): added support for comma-separated model lists

- Model field now accepts string arrays for fallback model prioritization.
- Extracted model list parsing into dedicated parseModelList helper function.
- Extended default model alias detection to validate all entries in comma-separated lists.

packages/coding-agent/CHANGELOG.md

@@ -6,6 +6,7 @@
 - Added extension API to set working/loading messages during streaming
 - Added task worker propagation of context files, skills, and prompt templates
 - Added subagent option to skip Python preflight checks when Python tooling is unused
+- Model field now accepts string arrays for fallback model prioritization
 
 ### Changed
 - Merged patch application warnings into edit tool diagnostics output
@@ -15,7 +16,7 @@
 ### Fixed
 - Rewrote empty or corrupted session files to restore valid headers
 - Improved patch applicator ambiguity errors with match previews and overlap detection
-
+- Fixed Task tool agent model resolution to honor comma-separated model lists
 ## [8.3.0] - 2026-01-25
 
 ### Changed

packages/coding-agent/src/discovery/helpers.ts

@@ -156,13 +156,23 @@ export function parseArrayOrCSV(value: unknown): string[] | undefined {
 	return undefined;
 }
 
+/**
+ * Parse model field into a prioritized list.
+ */
+export function parseModelList(value: unknown): string[] | undefined {
+	const parsed = parseArrayOrCSV(value);
+	if (!parsed) return undefined;
+	const normalized = parsed.map(entry => entry.trim()).filter(Boolean);
+	return normalized.length > 0 ? normalized : undefined;
+}
+
 /** Parsed agent fields from frontmatter (excludes source/filePath/systemPrompt) */
 export interface ParsedAgentFields {
 	name: string;
 	description: string;
 	tools?: string[];
 	spawns?: string[] | "*";
-	model?: string;
+	model?: string[];
 	output?: unknown;
 	thinkingLevel?: ThinkingLevel;
 }
@@ -202,7 +212,7 @@ export function parseAgentFields(frontmatter: Record<string, unknown>): ParsedAg
 	}
 
 	const output = frontmatter.output !== undefined ? frontmatter.output : undefined;
-	const model = typeof frontmatter.model === "string" ? frontmatter.model : undefined;
+	const model = parseModelList(frontmatter.model);
 	const thinkingLevel = parseThinkingLevel(frontmatter);
 
 	return { name, description, tools, spawns, model, output, thinkingLevel };

packages/coding-agent/src/task/agents.ts

@@ -18,7 +18,7 @@ interface AgentFrontmatter {
 	name: string;
 	description: string;
 	spawns?: string;
-	model?: string;
+	model?: string | string[];
 	thinkingLevel?: string;
 }
 

packages/coding-agent/src/task/executor.ts

@@ -40,6 +40,19 @@ import type {
 	SubagentWorkerResponse,
 } from "./worker-protocol";
 
+const DEFAULT_MODEL_ALIASES = new Set(["default", "pi/default", "omp/default"]);
+
+function normalizeModelPatterns(value: string | string[] | undefined): string[] {
+	if (!value) return [];
+	if (Array.isArray(value)) {
+		return value.map(entry => entry.trim()).filter(Boolean);
+	}
+	return value
+		.split(",")
+		.map(entry => entry.trim())
+		.filter(Boolean);
+}
+
 /** Options for worker execution */
 export interface ExecutorOptions {
 	cwd: string;
@@ -50,7 +63,7 @@ export interface ExecutorOptions {
 	index: number;
 	id: string;
 	context?: string;
-	modelOverride?: string;
+	modelOverride?: string | string[];
 	thinkingLevel?: ThinkingLevel;
 	outputSchema?: unknown;
 	enableLsp?: boolean;
@@ -283,23 +296,30 @@ export async function runSubprocess(options: ExecutorOptions): Promise<SingleRes
 	const serializedSettings = options.settingsManager?.serialize();
 	const availableModels = options.modelRegistry?.getAvailable() ?? [];
 
-	// Resolve model pattern to provider/modelId string
-	const modelPattern = modelOverride ?? agent.model;
+	// Resolve model pattern list to provider/modelId string
+	const modelPatterns = normalizeModelPatterns(modelOverride ?? agent.model);
 	let resolvedModel: string | undefined;
-	if (modelPattern) {
-		// Handle omp/<role> or pi/<role> aliases (e.g., "omp/slow", "pi/fast")
-		let effectivePattern = modelPattern;
-		const lower = modelPattern.toLowerCase();
-		if (lower.startsWith("omp/") || lower.startsWith("pi/")) {
-			const role = lower.startsWith("omp/") ? modelPattern.slice(4) : modelPattern.slice(3);
-			const roles = serializedSettings?.modelRoles as Record<string, string> | undefined;
-			const configured = roles?.[role] ?? roles?.[role.toLowerCase()];
-			if (configured) {
-				effectivePattern = configured;
+	if (modelPatterns.length > 0) {
+		const roles = serializedSettings?.modelRoles as Record<string, string> | undefined;
+		for (const pattern of modelPatterns) {
+			const normalized = pattern.trim().toLowerCase();
+			if (!normalized || DEFAULT_MODEL_ALIASES.has(normalized)) {
+				continue;
+			}
+			let effectivePattern = pattern;
+			if (normalized.startsWith("omp/") || normalized.startsWith("pi/")) {
+				const role = normalized.startsWith("omp/") ? pattern.slice(4) : pattern.slice(3);
+				const configured = roles?.[role] ?? roles?.[role.toLowerCase()];
+				if (configured) {
+					effectivePattern = configured;
+				}
+			}
+			const { model } = parseModelPattern(effectivePattern, availableModels);
+			if (model) {
+				resolvedModel = formatModelString(model);
+				break;
 			}
 		}
-		const { model } = parseModelPattern(effectivePattern, availableModels);
-		resolvedModel = model ? formatModelString(model) : undefined;
 	}
 	const sessionFile = subtaskSessionFile ?? null;
 	const spawnsEnv = agent.spawns === undefined ? "" : agent.spawns === "*" ? "*" : agent.spawns.join(",");

packages/coding-agent/src/task/index.ts

@@ -163,10 +163,14 @@ export class TaskTool implements AgentTool<typeof taskSchema, TaskToolDetails, T
 		const { agent: agentName, context, output: outputSchema, isolated } = params;
 		const isIsolated = isolated === true;
 
-		const isDefaultModelAlias = (value: string | undefined): boolean => {
+		const isDefaultModelAlias = (value: string | string[] | undefined): boolean => {
 			if (!value) return true;
-			const normalized = value.trim().toLowerCase();
-			return normalized === "default" || normalized === "pi/default" || normalized === "omp/default";
+			const values = Array.isArray(value) ? value : [value];
+			if (values.length === 0) return true;
+			return values.every(entry => {
+				const normalized = entry.trim().toLowerCase();
+				return normalized === "default" || normalized === "pi/default" || normalized === "omp/default";
+			});
 		};
 
 		// Validate agent exists

packages/coding-agent/src/task/types.ts

@@ -97,7 +97,7 @@ export interface AgentDefinition {
 	systemPrompt: string;
 	tools?: string[];
 	spawns?: string[] | "*";
-	model?: string;
+	model?: string[];
 	thinkingLevel?: ThinkingLevel;
 	output?: unknown;
 	source: AgentSource;
@@ -122,7 +122,7 @@ export interface AgentProgress {
 	toolCount: number;
 	tokens: number;
 	durationMs: number;
-	modelOverride?: string;
+	modelOverride?: string | string[];
 	/** Data extracted by registered subprocess tool handlers (keyed by tool name) */
 	extractedToolData?: Record<string, unknown[]>;
 }
@@ -142,7 +142,7 @@ export interface SingleResult {
 	truncated: boolean;
 	durationMs: number;
 	tokens: number;
-	modelOverride?: string;
+	modelOverride?: string | string[];
 	error?: string;
 	aborted?: boolean;
 	/** Aggregated usage from the subprocess, accumulated incrementally from message_end events. */