cli: default exec cwd to container workspace folder

[bilby91]

Summary

devcontainer exec used to leave WorkingDir empty when --working-dir wasn't passed, which made the runtime fall back to the image's WORKDIR. For stock devcontainer base images those happen to coincide with the spec's containerWorkspaceFolder, but a custom Dockerfile with a different WORKDIR would land the exec'd command outside the project — surprising for users running devcontainer exec ls.

Default to cfg.ContainerWorkspaceFolder when --working-dir is empty. The flag still overrides.

Test plan

• `devcontainer exec --no-tty -- pwd` → `/workspaces/`
• `devcontainer exec --no-tty --working-dir /tmp -- pwd` → `/tmp` (override still works)
• `go vet`, `golangci-lint run`, linux cross-build clean

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • The exec command now defaults to the container workspace folder as the working directory when --working-dir is not specified, providing more intuitive behavior for common use cases.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 61059bf9-5af5-4796-85db-ea5b5f810c2b

📥 Commits

Reviewing files that changed from the base of the PR and between 47b6958 and 421773b.

📒 Files selected for processing (1)

• cmd/devcontainer/exec.go

---

📝 Walkthrough

Walkthrough

The exec command in cmd/devcontainer/exec.go now defaults the container execution working directory to the resolved container workspace folder (cfg.ContainerWorkspaceFolder) when the --working-dir flag is not provided, rather than leaving it empty. This computed default is wired into the ExecOptions structure.

Changes

Exec Working Directory Default

Layer / File(s)	Summary
Working directory defaulting logic cmd/devcontainer/exec.go	A computed wd variable defaults WorkingDir to cfg.ContainerWorkspaceFolder when --working-dir is omitted, and this value is passed to ExecOptions.WorkingDir.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Poem

🐰 A rabbit hops through working paths,
No flag means home—a sensible default.
The workspace blooms where execution lands,
No empty strings to break our hopeful stance.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'cli: default exec cwd to container workspace folder' accurately and concisely describes the main change: making the exec command default its working directory to the container workspace folder.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch cli/exec-default-cwd

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}