Migrate proposals into the WASI monorepo

.gitignore

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-*.wasm
+*.wasm
+tmp/

proposals/cli/LICENSE.md

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+Copyright © 2019-2024 the Contributors to the WASI Specification, published
+by the [WebAssembly Community Group][cg] under the
+[W3C Community Contributor License Agreement (CLA)][cla]. A human-readable
+[summary][summary] is available.
+
+[cg]: https://www.w3.org/community/webassembly/
+[cla]: https://www.w3.org/community/about/agreements/cla/
+[summary]: https://www.w3.org/community/about/agreements/cla-deed/

proposals/cli/README.md

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+# WASI CLI World
+
+A proposed [WebAssembly System Interface](https://github.com/WebAssembly/WASI) API.
+
+### Current Phase
+
+wasi-cli is currently in [Phase 3].
+
+[Phase 3]:  https://github.com/WebAssembly/WASI/blob/main/Proposals.md#phase-3---implementation-phase-cg--wg
+
+### Champions
+
+- Dan Gohman
+
+### Portability Criteria
+
+WASI CLI must have host implementations which can pass the testsuite
+on at least Windows, macOS, and Linux.
+
+WASI CLI must have at least two complete independent implementations.
+
+## Table of Contents
+
+- [Introduction](#introduction)
+- [Goals [or Motivating Use Cases, or Scenarios]](#goals-or-motivating-use-cases-or-scenarios)
+- [Non-goals](#non-goals)
+- [API walk-through](#api-walk-through)
+  - [Use case 1](#use-case-1)
+  - [Use case 2](#use-case-2)
+- [Detailed design discussion](#detailed-design-discussion)
+  - [Should stdout be an `output-stream`?](#should-stdout-be-an-output-stream)
+  - [Should stderr be an `output-stream`?](#should-stderr-be-an-output-stream)
+  - [Should environment variables be arguments to `command`?](#should-environment-variables-be-arguments-to-command)
+- [Stakeholder Interest & Feedback](#stakeholder-interest--feedback)
+- [References & acknowledgements](#references--acknowledgements)
+
+### Introduction
+
+Wasi-cli a [World] proposal for a Command-Line Interface (CLI) environment. It provides APIs commonly available in such environments, such as filesystems and sockets, and also provides command-line facilities such as command-line arguments, environment variables, and stdio.
+
+[World]: https://github.com/WebAssembly/component-model/blob/main/design/mvp/WIT.md#wit-worlds
+
+### Goals
+
+Wasi-cli aims to be useful for:
+
+ - Interactive command-line argument programs.
+
+ - Servers that use filesystems, sockets, and related APIs and expect to be started with
+   a CLI-style command-line.
+
+ - Stream filters that read from standard input and write to standard output.
+
+### Non-goals
+
+Wasi-cli is not aiming to significantly re-imagine the concept of command-line interface programs. While WASI as a whole is exploring ideas such as [Typed Main], wasi-cli sticks to the traditional list-of-strings style command-line arguments.
+
+[Typed Main]: https://sunfishcode.github.io/typed-main-wasi-presentation/
+
+### API walk-through
+
+The full API documentation can be found [here](command.md).
+
+TODO [Walk through of how someone would use this API.]
+
+#### [Use case 1]
+
+[Provide example code snippets and diagrams explaining how the API would be used to solve the given problem]
+
+#### [Use case 2]
+
+[etc.]
+
+### Detailed design discussion
+
+#### Should stdout be an `output-stream`?
+
+For server use cases, standard output (stdout) is typically used as a log,
+where it's typically not meaningfully blocking, async, or fallible. It's just
+a place for the program to send messages to and forget about them. One option
+would be to give such use cases a dedicated API, which would have a single
+function to allow printing strings that doesn't return a `result`, meaning it
+never fails.
+
+However, it'd only be a minor simplification in practice, and dedicated cloud
+or edge use cases should ideally migrate to more specialized worlds than the
+wasi-cli world anyway, as they can result in much greater simplifications, so
+this doesn't seem worthwhile.
+
+#### Should stderr be an `output-stream`?
+
+This is similar to the question for stdout, but for standard error (stderr),
+it's a little more tempting to do something like this because stderr is used
+in this logging style by many kinds of applications.
+
+However, it seems better overall to keep stderr consistent with stdout, and
+focus our desires for simplification toward other worlds, which can achieve
+even greater simplifications.
+
+#### Should environment variables be arguments to `command`?
+
+Environment variables are useful in some non-cli use cases, so leaving them
+as separate imports means they can be used from worlds that don't have a
+`command` entrypoint.
+
+### Stakeholder Interest & Feedback
+
+TODO before entering Phase 3.
+
+[This should include a list of implementers who have expressed interest in implementing the proposal]
+
+### References & acknowledgements
+
+The concept of wasi-cli has been in development for over a year since the proposal is
+posted here, and many people have contributed ideas that have influenced.  Many thanks
+for valuable feedback and advice in particular from:
+
+- Luke Wagner
+- Pat Hickey