Add SupportsPlugins() capability detection and validation for agentic engines by Copilot · Pull Request #14516 · github/gh-aw

Copilot · 2026-02-08T12:56:39Z

Plugin installation is engine-specific and not universally supported. Currently only Copilot CLI supports the plugin install command.

Changes

Interface extension: Added SupportsPlugins() bool to CapabilityProvider interface
Base implementation: Added supportsPlugins field to BaseEngine with getter method
Engine configuration: Set supportsPlugins: true for Copilot engine only (Claude, Codex, Custom default to false)
Test coverage: Added tests verifying capability detection across all engines
Validation: Added validatePluginSupport() function that prevents compilation when plugins are specified with engines that don't support them
Error handling: Shows clear, actionable error messages when users try to use plugins with unsupported engines

Usage

engine := workflow.NewCopilotEngine()
if engine.SupportsPlugins() {
    // Generate plugin installation steps
    steps := workflow.GeneratePluginInstallationSteps(plugins, engine.GetID(), token)
}

Validation Example

When plugins are specified with an unsupported engine, compilation fails with:

✗ engine 'claude' does not support plugins. The following plugins cannot be installed: org/test-plugin

Only the 'copilot' engine currently supports plugin installation.

To fix this, either:
1. Remove the 'plugins' field from your workflow
2. Change to an engine that supports plugins (e.g., engine: copilot)

The implementation follows the existing Interface Segregation Principle pattern used for other capabilities (SupportsFirewall, SupportsHTTPTransport, etc.).

Original prompt

Look at #14377 and reimplement the agentic engine function to determine if an engine supports plugins. Only copilot supports it now.

Ignore the other changes

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- Added SupportsPlugins() to CapabilityProvider interface - Added supportsPlugins field to BaseEngine struct - Implemented SupportsPlugins() method in BaseEngine - Updated CopilotEngine to set supportsPlugins: true - Other engines (Claude, Codex, Custom) default to false - Added tests to verify only Copilot supports plugins Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

pelikhan · 2026-02-08T13:16:34Z

@copilot if the engine does not support a plugin, show error when trying to use plugin

- Added validatePluginSupport() function in engine_validation.go - Validates plugins are only used with engines that support them - Currently only copilot engine supports plugins - Shows clear error message with actionable fixes when unsupported - Added comprehensive test coverage for validation - Integrated validation in compiler_orchestrator_tools.go Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

Copilot · 2026-02-08T13:25:24Z

@copilot if the engine does not support a plugin, show error when trying to use plugin

Added validation in commit 1b58416. When plugins are specified with an engine that doesn't support them (currently only copilot supports plugins), the compiler now shows a clear error message:

✗ engine 'claude' does not support plugins. The following plugins cannot be installed: org/test-plugin

Only the 'copilot' engine currently supports plugin installation.

To fix this, either:
1. Remove the 'plugins' field from your workflow
2. Change to an engine that supports plugins (e.g., engine: copilot)

The validation prevents compilation and lists all plugins that cannot be installed, making it clear to users what needs to be fixed.

Copilot

Pull request overview

Adds an explicit engine capability flag for plugin installation and enforces it during workflow compilation so plugins can’t be used with engines that don’t support installing them.

Changes:

Extended engine capability detection with SupportsPlugins() and added a default implementation on BaseEngine.
Added compile-time validation to reject workflows that specify plugins with engines that report SupportsPlugins() == false.
Added unit tests for plugin-support validation and engine capability detection; updated docs table entry.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
pkg/workflow/engine_validation_test.go	Adds tests covering plugin-support validation behavior and error message content.
pkg/workflow/engine_validation.go	Introduces `validatePluginSupport()` to fail compilation when plugins are used with unsupported engines.
pkg/workflow/copilot_engine_test.go	Adds assertions that Copilot supports plugins and other engines do not.
pkg/workflow/copilot_engine.go	Marks Copilot engine as `supportsPlugins: true`.
pkg/workflow/compiler_orchestrator_tools.go	Runs plugin-support validation during tools/markdown processing.
pkg/workflow/agentic_engine.go	Extends `CapabilityProvider` + `BaseEngine` with `SupportsPlugins()` capability plumbing.
docs/src/content/docs/agent-factory-status.mdx	Adds “Dependabot Burner” to the agent-factory status table.

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Copilot · 2026-02-08T13:44:06Z

pkg/workflow/engine_validation.go

+		// Build error message listing the plugins that were specified
+		pluginsList := strings.Join(pluginInfo.Plugins, ", ")
+
+		return fmt.Errorf("engine '%s' does not support plugins. The following plugins cannot be installed: %s\n\nOnly the 'copilot' engine currently supports plugin installation.\n\nTo fix this, either:\n1. Remove the 'plugins' field from your workflow\n2. Change to an engine that supports plugins (e.g., engine: copilot)\n\nSee: %s",


validatePluginSupport currently hard-codes that only the 'copilot' engine supports plugin installation and returns an error for any other engine with plugins. This conflicts with the existing behavior where Claude and Codex engines still generate plugin installation steps (e.g., in their GetInstallationSteps implementations), and there are tests/workflows that compile plugins with those engines. Please align the codebase in one direction: either (a) mark Claude/Codex as SupportsPlugins=true and update the error message to list supported engines dynamically, or (b) remove/disable plugin-install step generation (and related tests/docs) for Claude/Codex so validation matches actual support.

Suggested change

return fmt.Errorf("engine '%s' does not support plugins. The following plugins cannot be installed: %s\n\nOnly the 'copilot' engine currently supports plugin installation.\n\nTo fix this, either:\n1. Remove the 'plugins' field from your workflow\n2. Change to an engine that supports plugins (e.g., engine: copilot)\n\nSee: %s",

return fmt.Errorf("engine '%s' does not support plugins. The following plugins cannot be installed: %s\n\nTo fix this, either:\n1. Remove the 'plugins' field from your workflow\n2. Change to an engine that supports plugins (see the documentation for supported engines)\n\nSee: %s",

Copilot · 2026-02-08T13:44:07Z

pkg/workflow/copilot_engine_test.go

+func TestOtherEnginesNoPluginSupport(t *testing.T) {
+	// Test that only Copilot engine supports plugins
+	engines := []CodingAgentEngine{
+		NewClaudeEngine(),
+		NewCodexEngine(),
+		NewCustomEngine(),
+	}
+
+	for _, engine := range engines {
+		if engine.SupportsPlugins() {
+			t.Errorf("Expected engine '%s' to not support plugins, but it does", engine.GetID())
+		}
+	}


This new test codifies that Claude/Codex/Custom engines do not support plugins, but other parts of the workflow package currently generate plugin installation steps for Claude and Codex. If plugins are truly Copilot-only, those engine implementations (and any tests expecting plugin installs for them) should be updated/removed; otherwise this test should be updated to reflect actual supported engines.

Copilot · 2026-02-08T13:44:07Z

pkg/workflow/engine_validation_test.go

+		{
+			name: "plugins with claude engine (not supported)",
+			pluginInfo: &PluginInfo{
+				Plugins: []string{"org/plugin1"},
+			},
+			engineID:    "claude",
+			expectError: true,
+			errorMsg:    "does not support plugins",
+		},
+		{
+			name: "plugins with codex engine (not supported)",
+			pluginInfo: &PluginInfo{
+				Plugins: []string{"org/plugin1", "org/plugin2"},
+			},
+			engineID:    "codex",
+			expectError: true,
+			errorMsg:    "does not support plugins",
+		},
+		{
+			name: "plugins with custom engine (not supported)",
+			pluginInfo: &PluginInfo{
+				Plugins: []string{"org/plugin1"},
+			},
+			engineID:    "custom",
+			expectError: true,
+			errorMsg:    "does not support plugins",
+		},


These tests assume plugins are only supported for the 'copilot' engine. That assumption currently conflicts with existing plugin compilation/import tests and engine installation logic that include 'claude plugin install' / 'codex plugin install' steps. Please reconcile: either update SupportsPlugins defaults for those engines and adjust validation/tests, or remove non-copilot plugin installation support everywhere so this validation behavior is consistent.

Copilot · 2026-02-08T13:44:07Z

pkg/workflow/agentic_engine.go

 	// SupportsFirewall returns true if this engine supports network firewalling/sandboxing
 	// When true, the engine can enforce network restrictions defined in the workflow
 	SupportsFirewall() bool
+
+	// SupportsPlugins returns true if this engine supports plugin installation
+	// When true, plugins can be installed using the engine's plugin install command
+	SupportsPlugins() bool


The interface hierarchy comment block above lists CapabilityProvider methods but doesn't mention SupportsPlugins, even though it is now part of the interface. Please update that documentation list to keep the file-level architecture docs accurate.

Initial plan

428352a

Copilot AI assigned Copilot and pelikhan Feb 8, 2026

Copilot started work on behalf of pelikhan February 8, 2026 12:56 View session

Copilot AI and others added 2 commits February 8, 2026 13:05

Verified implementation with tests and builds

1f04871

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

Copilot AI changed the title ~~[WIP] Reimplement agentic engine function for plugin support~~ Add SupportsPlugins() capability detection for agentic engines Feb 8, 2026

Copilot AI requested a review from pelikhan February 8, 2026 13:12

Copilot finished work on behalf of pelikhan February 8, 2026 13:12

github-actions bot mentioned this pull request Feb 8, 2026

Smoke Test: Copilot - 21798668139 #14518

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Copilot started work on behalf of pelikhan February 8, 2026 13:17 View session

Copilot AI changed the title ~~Add SupportsPlugins() capability detection for agentic engines~~ Add SupportsPlugins() capability detection and validation for agentic engines Feb 8, 2026

Copilot finished work on behalf of pelikhan February 8, 2026 13:26

pelikhan approved these changes Feb 8, 2026

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pelikhan marked this pull request as ready for review February 8, 2026 13:40

Copilot AI review requested due to automatic review settings February 8, 2026 13:40

pelikhan merged commit ee7394a into main Feb 8, 2026
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pelikhan deleted the copilot/reimplement-agentic-engine-function branch February 8, 2026 13:40

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Add SupportsPlugins() capability detection and validation for agentic engines#14516

Add SupportsPlugins() capability detection and validation for agentic engines#14516
pelikhan merged 4 commits intomainfrom
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	return fmt.Errorf("engine '%s' does not support plugins. The following plugins cannot be installed: %s\n\nOnly the 'copilot' engine currently supports plugin installation.\n\nTo fix this, either:\n1. Remove the 'plugins' field from your workflow\n2. Change to an engine that supports plugins (e.g., engine: copilot)\n\nSee: %s",
	return fmt.Errorf("engine '%s' does not support plugins. The following plugins cannot be installed: %s\n\nTo fix this, either:\n1. Remove the 'plugins' field from your workflow\n2. Change to an engine that supports plugins (see the documentation for supported engines)\n\nSee: %s",

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