diff --git a/packages/coding-agent/CHANGELOG.md b/packages/coding-agent/CHANGELOG.md
index eb2fa5a9..0bf10123 100644
--- a/packages/coding-agent/CHANGELOG.md
+++ b/packages/coding-agent/CHANGELOG.md
@@ -8,6 +8,7 @@
 
 ### Fixed
 
+- Fixed `--model` resolution for authenticated custom model IDs whose slash prefix matches an unauthenticated built-in provider ([#5643](https://github.com/earendil-works/pi/issues/5643)).
 - Fixed `/share` and `/export` HTML exports to use the active fallback theme when the configured custom theme no longer exists ([#5596](https://github.com/earendil-works/pi/issues/5596)).
 - Fixed custom fallback model IDs with `:<thinking>` suffixes to preserve the requested thinking level when the provider template model does not advertise reasoning ([#5552](https://github.com/earendil-works/pi/issues/5552)).
 
diff --git a/packages/coding-agent/src/core/model-resolver.ts b/packages/coding-agent/src/core/model-resolver.ts
index 292ccf37..0017df00 100644
--- a/packages/coding-agent/src/core/model-resolver.ts
+++ b/packages/coding-agent/src/core/model-resolver.ts
@@ -422,6 +422,27 @@ export function resolveCliModel(options: {
 	});
 
 	if (model) {
+		// If provider inference matched an unauthenticated provider/model pair, prefer
+		// one exact raw model-id match that is authenticated. This keeps
+		// "provider/model" syntax preferred when usable, but handles models whose
+		// literal id starts with a known provider name (for example
+		// commandcode model id "xiaomi/mimo-v2.5-pro").
+		if (inferredProvider) {
+			const rawExactMatches = availableModels.filter(
+				(m) => m.id.toLowerCase() === cliModel.toLowerCase() && !modelsAreEqual(m, model),
+			);
+			if (rawExactMatches.length > 0 && !modelRegistry.hasConfiguredAuth(model)) {
+				const authenticatedRawMatches = rawExactMatches.filter((m) => modelRegistry.hasConfiguredAuth(m));
+				if (authenticatedRawMatches.length === 1) {
+					return {
+						model: authenticatedRawMatches[0],
+						thinkingLevel: undefined,
+						warning: undefined,
+						error: undefined,
+					};
+				}
+			}
+		}
 		return { model, thinkingLevel, warning, error: undefined };
 	}
 
diff --git a/packages/coding-agent/test/model-resolver.test.ts b/packages/coding-agent/test/model-resolver.test.ts
index 32861a9e..163c3ab5 100644
--- a/packages/coding-agent/test/model-resolver.test.ts
+++ b/packages/coding-agent/test/model-resolver.test.ts
@@ -344,6 +344,7 @@ describe("resolveCliModel", () => {
 		};
 		const registry = {
 			getAll: () => [...allModels, zaiModel, gatewayModel],
+			hasConfiguredAuth: () => true,
 		} as unknown as Parameters<typeof resolveCliModel>[0]["modelRegistry"];
 
 		const result = resolveCliModel({
@@ -356,6 +357,46 @@ describe("resolveCliModel", () => {
 		expect(result.model?.id).toBe("glm-5");
 	});
 
+	test("prefers an authenticated exact raw model id over an unauthenticated inferred provider", () => {
+		const commandcodeModel: Model<"anthropic-messages"> = {
+			id: "xiaomi/mimo-v2.5-pro",
+			name: "Xiaomi MiMo via Commandcode",
+			api: "anthropic-messages",
+			provider: "commandcode",
+			baseUrl: "https://example.invalid",
+			reasoning: false,
+			input: ["text"],
+			cost: { input: 1, output: 2, cacheRead: 0.1, cacheWrite: 1 },
+			contextWindow: 128000,
+			maxTokens: 8192,
+		};
+		const xiaomiModel: Model<"anthropic-messages"> = {
+			id: "mimo-v2.5-pro",
+			name: "Xiaomi MiMo",
+			api: "anthropic-messages",
+			provider: "xiaomi",
+			baseUrl: "https://api.xiaomimimo.com",
+			reasoning: false,
+			input: ["text"],
+			cost: { input: 1, output: 2, cacheRead: 0.1, cacheWrite: 1 },
+			contextWindow: 128000,
+			maxTokens: 8192,
+		};
+		const registry = {
+			getAll: () => [...allModels, commandcodeModel, xiaomiModel],
+			hasConfiguredAuth: (model: Model<"anthropic-messages">) => model.provider === "commandcode",
+		} as unknown as Parameters<typeof resolveCliModel>[0]["modelRegistry"];
+
+		const result = resolveCliModel({
+			cliModel: "xiaomi/mimo-v2.5-pro",
+			modelRegistry: registry,
+		});
+
+		expect(result.error).toBeUndefined();
+		expect(result.model?.provider).toBe("commandcode");
+		expect(result.model?.id).toBe("xiaomi/mimo-v2.5-pro");
+	});
+
 	test("resolves provider-prefixed fuzzy patterns (openrouter/qwen -> openrouter model)", () => {
 		const registry = {
 			getAll: () => allModels,