Shell Runner: Auto-Select & Better Status Display

Ever felt that sting of a cryptic error message when your development environment just wouldn't cooperate? You're not alone! For many of us, diving into code means dealing with the intricacies of our tools, and sometimes, those tools can be a bit, well, unhelpful. One such area is the shell runner, the unsung hero that bridges your IDE with your command line. Until now, if the necessary sandbox container image was missing, you were met with a rather unceremonious:

ERROR: Sandbox container image is missing. Did you run `:init` ?

This message, while technically informative, presents a frustrating user experience. Why? Firstly, you're completely blocked; there's nothing you can do until you remember to run that specific :init command. There's no graceful way to continue working or even to understand what's going wrong. Secondly, and perhaps more importantly, there's a distinct lack of visibility into which shell runner is even being considered, let alone how it's configured. This proposal aims to change all that, bringing auto-selection and a clearer status display for your shell runner, making your development workflow smoother and more intuitive.

The Smarter Way to Run Your Shell

Imagine a world where your development environment just works, without you having to micromanage its components. That's the vision behind this enhancement. The core idea is simple yet powerful: automatically assign a suitable shell runner when a new session begins. This means if you have Podman installed and configured, it'll be the go-to choice, offering the benefits of containerized environments like isolation and reproducibility. If Podman isn't available or ready to go, it'll gracefully fall back to using your host machine's shell. But it doesn't stop there. To keep you informed, the status bar will prominently display which runner is active and its current state.

This isn't just about fixing a bug; it's about elevating the user experience. No more guesswork, no more hitting dead ends with obscure error messages. We're talking about a proactive system that anticipates your needs and provides clear feedback. The new system will be designed with two key requirements in mind. First, the auto-detection and assignment of the shell runner. The system will intelligently check if Podman is available and its sandbox image exists. If both conditions are met, it will leverage the PodmanShellRunner, giving you the power and isolation of containers. Should Podman not be ready, or if the necessary image is missing, it will automatically default to the HostShellRunner, ensuring you can always proceed with your work without interruption. This fallback mechanism is crucial for maintaining productivity.

Second, the status bar display. This is where transparency comes into play. When the PodmanShellRunner is in use, you'll see a clear indicator, perhaps something like 📦 <container-id>, showing you exactly which container is handling your shell commands. This provides immediate confirmation and context. If, however, the system falls back to the HostShellRunner, you'll be notified with a visual cue, like ⚠ host (run :init). The warning symbol and the reminder to run :init serve as a gentle nudge, letting you know you're using the host environment and how to switch to the more robust containerized option if desired. This dual approach ensures that you're always aware of your shell environment's status, empowering you to make informed decisions about your workflow.

A Step-by-Step Journey to Enhanced Shell Management

Implementing these improvements involves a well-defined plan, touching several key components of the development environment. Let's break down the implementation plan and see how we're going to achieve this smarter, more transparent shell experience. Our journey begins with foundational elements, ensuring we have the right building blocks in place.

Step 1: Introducing the HostShellRunner

First, we need to formally introduce the HostShellRunner into our toolkit. This will be added to tools.go, acting as the designated handler for when Podman isn't the chosen runner. This struct will encapsulate the configuration needed to interact with the host's shell. It will include essential methods: Run to execute commands on the host, Restart and Close which will be no-operation (no-op) functions since direct management isn't needed for the host runner, and importantly, AllowFallback which will also be a no-op. A key addition here is the RunnerType() method, which will simply return `