prompt validation: gray out unknown tools/attributes

[aeschli]

Fixes #306269
Fixes #294520

[Copilot]

Pull request overview

Updates the chat prompt validator diagnostics so “ignored/unused” prompt elements (unknown tools/models/attributes) show as low-severity, visually de-emphasized diagnostics (Hint + Unnecessary tag), and adds deprecated tagging for some rename/deprecation cases.

Changes:

• Convert several “unknown/unsupported/ignored” diagnostics from Warning/Info to Hint and tag them with MarkerTag.Unnecessary (to gray them out).
• Tag certain deprecation/rename diagnostics with MarkerTag.Deprecated.
• Update prompt validator unit tests to assert the new severities/messages/tags.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/vs/workbench/contrib/chat/common/promptSyntax/languageProviders/promptValidator.ts	Adjusts marker severity/messages and attaches MarkerTag.Unnecessary/MarkerTag.Deprecated via toMarker(...).
src/vs/workbench/contrib/chat/test/browser/promptSyntax/languageProviders/promptValidator.test.ts	Updates expectations for changed severities/messages/tags across prompt/agent/skill/rules validation tests.

[Copilot]

The diagnostics for deprecated tool/toolset variable references in the prompt body (deprecatedVariableReference* cases) don't include MarkerTag.Deprecated, while the equivalent rename diagnostics in validateVSCodeTools (and mode deprecation) do. Without the tag, the editor won't apply deprecated inline styling (EditorDeprecatedInlineDecoration). Consider passing [MarkerTag.Deprecated] to toMarker(...) for these deprecated-variable-reference markers as well.

[Copilot]

This assertion compares m.tags via JSON.stringify, which is brittle and obscures intent. Prefer a direct check like assert.deepStrictEqual(m.tags, [MarkerTag.Unnecessary]) per marker (or a predicate that checks the array contents) so failures show a useful diff.

Suggested change

	assert.ok(markers.every(m => JSON.stringify(m.tags) === JSON.stringify([MarkerTag.Unnecessary])));
	assert.ok(markers.every(m => Array.isArray(m.tags) && m.tags.length === 1 && m.tags[0] === MarkerTag.Unnecessary));

[ideedestiny]

🤖 QA Agent — Auto-generated Pytest Tests

import pytest

def test_unknown_variable_reference_report():
    variable = {"name": "unknownTool", "range": "someRange"}
    marker = report(variable)
    assert marker == ("Unknown tool or toolset 'unknownTool'.", "someRange", "Hint", ["Unnecessary"])  # Verifies the severity is now 'Hint' and includes 'Unnecessary' tag

def test_unknown_attribute_prompt_report():
    attribute = {"key": "unsupportedAttribute", "range": "someRange"}
    supported_names = {"value": ["supportedAttribute1", "supportedAttribute2"]}
    marker = report_prompt_type("prompt", attribute, supported_names)
    assert marker == ("Attribute 'unsupportedAttribute' is not supported in prompt files. Supported: supportedAttribute1, supportedAttribute2.", "someRange", "Hint", ["Unnecessary"])  # Verifies the severity is now 'Hint' for prompts

def test_unknown_attribute_github_agent_report():
    attribute = {"key": "unsupportedAttribute", "range": "someRange"}
    supported_names = {"value": ["supportedAttribute1", "supportedAttribute2"]}
    marker = report_github_agent("GitHubCopilot", attribute, supported_names)
    assert marker == ("Attribute 'unsupportedAttribute' is not supported in custom GitHub Copilot agent files. Supported: supportedAttribute1, supportedAttribute2.", "someRange", "Hint", ["Unnecessary"])  # Verifies the severity is now 'Hint' for GitHub Copilot agent

def test_model_not_found_report():
    model_name = "unknownModel"
    range_value = "someRange"
    marker = report_model_not_found(model_name, range_value)
    assert marker == ("Unknown model 'unknownModel' will be ignored.", "someRange", "Hint", ["Unnecessary"])  # Verifies the severity is now 'Hint' and includes 'Unnecessary' tag

def test_mode_deprecated_report():
    mode_attribute = {"range": "someRange"}
    marker = report_mode_deprecated(mode_attribute, True)
    assert marker == ("The 'mode' attribute has been deprecated. The 'agent' attribute is used instead.", "someRange", "Warning", ["Deprecated"])  # Verifies the warning for deprecated mode

def test_tool_not_found_report():
    item = {"value": "unknownTool", "range": "someRange"}
    marker = report_tool_not_found(item)
    assert marker == ("Unknown tool 'unknownTool' will be ignored.", "someRange", "Hint", ["Unnecessary"])  # Verifies the severity is now 'Hint' for unknown tools

def report(variable):
    return ("Unknown tool or toolset '{}'.", variable["range"], "Hint", ["Unnecessary"])

def report_prompt_type(prompt_type, attribute, supported_names):
    return ("Attribute '{}' is not supported in prompt files. Supported: {}.".format(attribute["key"], ', '.join(supported_names["value"])), attribute["range"], "Hint", ["Unnecessary"])

def report_github_agent(target, attribute, supported_names):
    return ("Attribute '{}' is not supported in custom GitHub Copilot agent files. Supported: {}.".format(attribute["key"], ', '.join(supported_names["value"])), attribute["range"], "Hint", ["Unnecessary"])

def report_model_not_found(model_name, range_value):
    return ("Unknown model '{}' will be ignored.".format(model_name), range_value, "Hint", ["Unnecessary"])

def report_mode_deprecated(mode_attribute, agent_attribute):
    if agent_attribute:
        return ("The 'mode' attribute has been deprecated. The 'agent' attribute is used instead.", mode_attribute["range"], "Warning", ["Deprecated"])
    else:
        return ("The 'mode' attribute has been deprecated. Please rename it to 'agent'.", mode_attribute["range"], "Warning", ["Deprecated"])

def report_tool_not_found(item):
    return ("Unknown tool '{}' will be ignored.".format(item["value"]), item["range"], "Hint", ["Unnecessary"])