fix: derive workspace from devcontainer config, support subfolder opening

[michidk]

Summary

When --config points to a devcontainer.json, derive the workspace root from the config location instead of requiring the path argument to be the project root. If the path argument is a subdirectory of the derived workspace root, the relative path is appended to the container workspace folder in the VS Code URI.

Example — open a monorepo subfolder in a devcontainer:

# Project structure:
# /home/me/monorepo/.devcontainer/devcontainer.json
# /home/me/monorepo/frontend/
# /home/me/monorepo/backend/

vscli open --config /home/me/monorepo/.devcontainer/devcontainer.json /home/me/monorepo/backend
# Opens VS Code at /workspaces/monorepo/backend inside the container

Changes

• main.rs: workspace_root_from_config() walks up from config path to find the .devcontainer parent, then uses its parent as workspace root. Extracts subfolder if path arg is a subdirectory of the root.
• launch.rs: launch() accepts optional subfolder: Option<&Path> parameter, passed through to workspace.open().
• workspace.rs: open() appends subfolder (with backslash normalization) to the container workspace path in the URI.
• container.rs: Updated open() call site to pass None for subfolder.

Handles

• Configs in .devcontainer/ folders (walks up to find it)
• Nested configs like .devcontainer/python/devcontainer.json
• Host path subfolders (extracted as relative path)
• Normal usage without --config (no behavior change)
• Windows backslash normalization in subfolder paths

Supersedes #185. Fixes #82.

---

Summary by cubic

Derives the workspace root from the devcontainer.json location when using --config and allows opening a subfolder inside the container if the given path is within that root. Fixes #82.

• Bug Fixes
  • Walks up from the config to find the .devcontainer folder and uses its parent as the workspace root; supports nested configs.
  • If the provided path is a subdirectory, appends its relative path to the container workspace in the VS Code URI; normalizes Windows backslashes.
  • No behavior change when not using --config.

^{Written for commit 71f68cc. Summary will update on new commits.}

[cubic-dev-ai]

1 issue found across 4 files

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="src/main.rs">

<violation number="1" location="src/main.rs:104">
P2: When `--config` resolves to an external config, this now derives the workspace root from the config store path and ignores the user’s project path, so `vscli open --config rust-dev ~/projects/my-app` opens the config directory instead of the project. Preserve the path argument when it isn’t under the config-derived root.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

P2: When --config resolves to an external config, this now derives the workspace root from the config store path and ignores the user’s project path, so vscli open --config rust-dev ~/projects/my-app opens the config directory instead of the project. Preserve the path argument when it isn’t under the config-derived root.

Prompt for AI agents

Check if this issue is valid — if so, understand the root cause and fix it. At src/main.rs, line 104:

<comment>When `--config` resolves to an external config, this now derives the workspace root from the config store path and ignores the user’s project path, so `vscli open --config rust-dev ~/projects/my-app` opens the config directory instead of the project. Preserve the path argument when it isn’t under the config-derived root.</comment>

<file context>
@@ -70,28 +95,34 @@ fn main() -> Result<()> {
                 .as_ref()
                 .and_then(|p| config_store::config_name_from_path(p, &config_store));
 
+            let (workspace_path, subfolder) = if let Some(ref config) = resolved_config {
+                workspace_root_from_config(config, &path)?
+            } else {
</file context>

Suggested change

	let (workspace_path, subfolder) = if let Some(ref config) = resolved_config {
	workspace_root_from_config(config, &path)?
	} else {
	(path.clone(), None)
	};
	let (workspace_path, subfolder) = if let Some(ref config) = resolved_config {
	let (root, sub) = workspace_root_from_config(config, &path)?;
	let path_abs = path.canonicalize().unwrap_or_else(|_| path.clone());
	if path_abs.starts_with(&root) {
	(root, sub)
	} else {
	(path.clone(), None)
	}
	} else {
	(path.clone(), None)
	};