The 'excludeAgent' attribute must be an array.

[CatsMiaow]

Does this issue occur when all extensions are disabled?: Yes

• VS Code Version:

Version: 1.106.0 (user setup)
Commit: ac4cbdf48759c7d8c3eb91ffe6bb04316e263c57
Date: 2025-11-11T16:02:25.943Z
Electron: 37.7.0
ElectronBuildId: 12597478
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Windows_NT x64 10.0.26100

• OS Version: Window 11, MacOS

Steps to Reproduce:

• https://github.blog/changelog/2025-11-12-copilot-code-review-and-coding-agent-now-support-agent-specific-instructions/
• https://docs.github.com/ko/copilot/how-tos/configure-custom-instructions/add-repository-instructions#creating-path-specific-custom-instructions

According to the GitHub blog guide above, the excludeAgent property in the instructions file should be provided as a string.

vscode/src/vs/workbench/contrib/chat/common/promptSyntax/languageProviders/promptValidator.ts

Lines 390 to 399 in 858b6b7

	private validateExcludeAgent(attributes: IHeaderAttribute[], report: (markers: IMarkerData) => void): undefined {
	const attribute = attributes.find(attr => attr.key === PromptHeaderAttributes.excludeAgent);
	if (!attribute) {
	return;
	}
	if (attribute.value.type !== 'array') {
	report(toMarker(localize('promptValidator.excludeAgentMustBeArray', "The 'excludeAgent' attribute must be an array."), attribute.value.range, MarkerSeverity.Error));
	return;
	}
	}

In the actual code logic, it throws an error if the value isn’t an array.
Providing the value as an array doesn’t cause a syntax error.
However, since the only valid values are code-review or coding-agent the input should be a string.
Otherwise, the guide should be updated to specify an array instead of a string.

[CatsMiaow]

In addition, if exclaudeAgent is set to coding-agent in the instructions, should probably exclude references to the instructions in VS Code Copilot Agent Chat as well.

[ThomSMG]

Right. if excludeAgent is set to coding-agent it should not be picked up by Copilot in an IDE context. But it is (Version: 1.108.0 (Universal) - Mac OS).

My clumsy workaround:

---
applyTo: "**"
excludeAgent: "coding-agent"
---

# Code Review Instructions
ONLY CONTINUE READING THIS FILE when performing a code review on a PR on github.com. OTHERWISE, DO NOT PROCEED.

When reviewing code changes in a pull request (PR) apply the checks in the `/CODING_GUIDELINES.md` file.

Hi @aeschli ! Do you think this could be given some priority?

[aeschli]

fix for main: #291924
fix for release: #291925

[OrenMe]

@aeschli does it exclude it from vscode code agent if it's set to coding agent?