Proposal: explore interoperability conventions for AI coding

# Hi VS Code / GitHub Copilot team,

I recently created [opinionated-ts/ai-spec](https://github.com/opinionated-ts/ai-spec), an early community-driven effort to explore an open specification for interoperability between AI coding assistants and development environments.

The repository was created only recently, and the project is intentionally in an **early stage**. Nothing in the specification is considered final yet.

The reason for starting the project now is that AI-assisted development environments are increasingly implementing similar project-level concepts, while conventions around their structure, discovery, configuration, and behavior can differ between ecosystems.

`ai-spec` is exploring common conventions around areas such as:

* Agents
* Hooks
* Plugins
* Instructions and configuration
* Discovery and precedence
* Lifecycle behavior
* Project-level AI configuration
* Other conventions that may benefit from interoperability

The project is not intended to replace VS Code, GitHub Copilot, or any provider-specific implementation.

Instead, the goal is to provide a community-driven place to compare existing approaches and determine whether some of these conventions can be made interoperable.

The repository currently contains the initial structure, contribution guidelines, and discussion process. Contributors are explicitly encouraged to investigate existing implementations and prior art before proposing new conventions.

I would appreciate feedback from the team on:

1. Which existing VS Code/Copilot conventions should be considered prior art.
2. Which interoperability problems you believe are worth solving.
3. Which areas should remain implementation-specific.
4. Whether existing VS Code/Copilot work already addresses parts of this problem.
5. Whether the team or community would be interested in participating while `ai-spec` is still being shaped.

### Repository and discussion

Repository: https://github.com/opinionated-ts/ai-spec

Contributing: https://github.com/opinionated-ts/ai-spec/blob/main/CONTRIBUTING.md

Discussions: https://github.com/opinionated-ts/ai-spec/discussions

This is intentionally an early-stage initiative rather than a request for immediate adoption.

The goal is to involve the ecosystems and their communities before the specification becomes mature, so that real-world implementations can help shape what should and should not be standardized.