PR #2958: fix model-resolver :variant sort order

pr-2958.patch

diff --git a/packages/coding-agent/src/core/model-resolver.ts b/packages/coding-agent/src/core/model-resolver.ts
index 1825274a..8b9a5cbf 100644
--- a/packages/coding-agent/src/core/model-resolver.ts
+++ b/packages/coding-agent/src/core/model-resolver.ts
@@ -131,12 +131,24 @@ function tryMatchModel(modelPattern: string, availableModels: Model<Api>[]): Mod
 	const datedVersions = matches.filter((m) => !isAlias(m.id));
 
 	if (aliases.length > 0) {
-		// Prefer alias - if multiple aliases, pick the one that sorts highest
-		aliases.sort((a, b) => b.id.localeCompare(a.id));
+		// Prefer aliases without a colon-variant suffix (e.g. "model" over "model:free").
+		// A longer string beats its own prefix in localeCompare, so without this
+		// "qwen/qwen3.6-plus:free" would silently win over "qwen/qwen3.6-plus".
+		aliases.sort((a, b) => {
+			const aHasSuffix = a.id.includes(":");
+			const bHasSuffix = b.id.includes(":");
+			if (aHasSuffix !== bHasSuffix) return aHasSuffix ? 1 : -1;
+			return b.id.localeCompare(a.id);
+		});
 		return aliases[0];
 	} else {
-		// No alias found, pick latest dated version
-		datedVersions.sort((a, b) => b.id.localeCompare(a.id));
+		// No alias found, pick latest dated version without a colon-variant suffix first.
+		datedVersions.sort((a, b) => {
+			const aHasSuffix = a.id.includes(":");
+			const bHasSuffix = b.id.includes(":");
+			if (aHasSuffix !== bHasSuffix) return aHasSuffix ? 1 : -1;
+			return b.id.localeCompare(a.id);
+		});
 		return datedVersions[0];
 	}
 }
diff --git a/packages/coding-agent/test/model-resolver.test.ts b/packages/coding-agent/test/model-resolver.test.ts
index 511e5408..256ed618 100644
--- a/packages/coding-agent/test/model-resolver.test.ts
+++ b/packages/coding-agent/test/model-resolver.test.ts
@@ -37,6 +37,30 @@ const mockModels: Model<"anthropic-messages">[] = [
 
 // Mock OpenRouter models with colons in IDs
 const mockOpenRouterModels: Model<"anthropic-messages">[] = [
+	{
+		id: "qwen/qwen3.6-plus",
+		name: "Qwen3.6 Plus",
+		api: "anthropic-messages",
+		provider: "openrouter",
+		baseUrl: "https://openrouter.ai/api/v1",
+		reasoning: true,
+		input: ["text", "image"],
+		cost: { input: 0.325, output: 1.95, cacheRead: 0, cacheWrite: 0 },
+		contextWindow: 1000000,
+		maxTokens: 65536,
+	},
+	{
+		id: "qwen/qwen3.6-plus:free",
+		name: "Qwen3.6 Plus (free)",
+		api: "anthropic-messages",
+		provider: "openrouter",
+		baseUrl: "https://openrouter.ai/api/v1",
+		reasoning: true,
+		input: ["text", "image"],
+		cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+		contextWindow: 1000000,
+		maxTokens: 65536,
+	},
 	{
 		id: "qwen/qwen3-coder:exacto",
 		name: "Qwen3 Coder Exacto",
@@ -131,6 +155,34 @@ describe("parseModelPattern", () => {
 		});
 	});
 
+	describe("colon-variant sort order", () => {
+		test("base model wins over :free when both exist", () => {
+			// "qwen3.6-plus" partial-matches both "qwen/qwen3.6-plus" and "qwen/qwen3.6-plus:free".
+			// The base model must win — not the :free variant.
+			const result = parseModelPattern("qwen3.6-plus", allModels);
+			expect(result.model?.id).toBe("qwen/qwen3.6-plus");
+			expect(result.thinkingLevel).toBeUndefined();
+		});
+
+		test("base model wins over :free with thinking level", () => {
+			const result = parseModelPattern("qwen3.6-plus:high", allModels);
+			expect(result.model?.id).toBe("qwen/qwen3.6-plus");
+			expect(result.thinkingLevel).toBe("high");
+		});
+
+		test("explicit :free suffix selects the free variant", () => {
+			const result = parseModelPattern("qwen/qwen3.6-plus:free", allModels);
+			expect(result.model?.id).toBe("qwen/qwen3.6-plus:free");
+			expect(result.thinkingLevel).toBeUndefined();
+		});
+
+		test("only :free exists — still matches it when no base model is available", () => {
+			const freeOnly = allModels.filter((m) => m.id !== "qwen/qwen3.6-plus");
+			const result = parseModelPattern("qwen3.6-plus", freeOnly);
+			expect(result.model?.id).toBe("qwen/qwen3.6-plus:free");
+		});
+	});
+
 	describe("OpenRouter models with colons in IDs", () => {
 		test("qwen3-coder:exacto matches the model with undefined thinking level", () => {
 			const result = parseModelPattern("qwen/qwen3-coder:exacto", allModels);
@@ -362,7 +414,7 @@ describe("resolveCliModel", () => {
 		} as unknown as Parameters<typeof resolveCliModel>[0]["modelRegistry"];
 
 		const result = resolveCliModel({
-			cliModel: "openrouter/qwen",
+			cliModel: "openrouter/qwen3-coder",
 			modelRegistry: registry,
 		});