[tool_extensibility] Prototype: Out-of-Process Isolate Extensions Architecture #190755

Overview

The goal of this prototype is to evaluate allowing custom, third-party, and out-of-tree platforms to extend Flutter CLI commands (doctor, config, create, devices, build, assemble, and run) through dedicated worker isolates without embedding platform-specific logic into the host tool codebase.

Architecture Highlights

• Pub Workspace Architecture: Encapsulates core DTOs, extension protocol contracts, and platform prototypes in dedicated sub-packages (flutter_tools_core, flutter_tools_extension, flutter_tools_extension_linux_prototype).
• Isolated Execution: Extension entrypoints run in dedicated worker isolates over a JSON-RPC protocol.
• Dynamic CLI Rebuilding: Commands mix in ExtensionArgParserMixin to dynamically re-parse flags and register subcommands based on loaded extensions.
• Pure Dependency Injection: Eliminates reliance on ambient AppContext / globals for extension managers.

Prototype Phases

• [tool_extensibility] Prototype Phase 1: Pub Workspace setup and sub-package structure #190745 - [tool_extensibility] Prototype Phase 1: Pub Workspace setup and sub-package structure
• [tool_extensibility] Prototype Phase 2: Generic RPC protocol base and isolate runner infrastructure #190746 - [tool_extensibility] Prototype Phase 2: Generic RPC protocol base and isolate runner infrastructure
• [tool_extensibility] Prototype Phase 3: DiagnosticsExtension and flutter doctor integration #190747 - [tool_extensibility] Prototype Phase 3: DiagnosticsExtension and flutter doctor integration
• [tool_extensibility] Prototype Phase 4: ConfigurationExtension and flutter config dynamic options #190748 - [tool_extensibility] Prototype Phase 4: ConfigurationExtension and flutter config dynamic options
• [tool_extensibility] Prototype Phase 5: TemplateService and dynamic ArgParser integration for flutter create #190749 - [tool_extensibility] Prototype Phase 5: TemplateService and dynamic ArgParser integration for flutter create
• [tool_extensibility] Prototype Phase 6: DeviceService and dynamic ExtensionBackedDevice discovery #190750 - [tool_extensibility] Prototype Phase 6: DeviceService and dynamic ExtensionBackedDevice discovery
• [tool_extensibility] Prototype Phase 7: BuildService, dynamic target registration, and flutter build integration #190752 - [tool_extensibility] Prototype Phase 7: BuildService, dynamic target registration, and flutter build integration
• [tool_extensibility] Prototype Phase 8: App lifecycle management, run, VM Service connection, and hot reload #190753 - [tool_extensibility] Prototype Phase 8: App lifecycle management, run, VM Service connection, and hot reload
• [tool_extensibility] Prototype Phase 9: Dynamic plugin resolution and native registrant generation #190754 - [tool_extensibility] Prototype Phase 9: Dynamic plugin resolution and native registrant generation