Support launching the devcontainer from a git worktree

[alliepiper]

Summary

Make .devcontainer/launch.sh work when invoked from a linked git worktree.

Two reasons it currently breaks:

1. .git is unreachable inside the container. In a worktree, .git is
   a file containing gitdir: <main-repo>/.git/worktrees/<name> — an
   absolute host path. The container only mounts the worktree at
   /home/coder/cccl, so the gitdir pointer (and the main .git it
   references via commondir) is unreachable. Every git operation in
   the container fails.

2. gh auth state is missing. The devcontainer bind-mounts
   ${localWorkspaceFolder}/.config → /home/coder/.config. In a fresh
   worktree, .config/gh/ doesn't exist, so
   devcontainer-utils-init-git falls through to an interactive
   gh auth login device flow on every startup.

Changes

.devcontainer/launch.sh launch_docker() now detects the worktree
case ([[ -f .git ]]) and:

• Bind-mounts the main repo's .git directory at its absolute host path
  inside the container, so both the absolute gitdir: pointer and the
  relative commondir resolve.
• Bind-mounts the main checkout's .config/gh (when present) into
  /home/coder/.config/gh, so gh auth status passes and
  devcontainer-utils-init-git skips the device flow.
• Prints a warning that the global cccl-build and cccl-wheelhouse
  docker volumes are shared across all worktrees and the main
  checkout (preexisting issue, but worth surfacing).
• If the main checkout has no .config/gh/ to share, additionally
  warns that init-git will block on gh auth login and recommends
  launching the main checkout's devcontainer first to populate auth
  state.

No-op when .git is a directory (regular checkout).

Test plan

• Pre-commit (shellcheck, codespell, etc.) passes on .devcontainer/launch.sh.
• End-to-end: .devcontainer/launch.sh -d -- bash -c '<git probes>'
  from the worktree completes without hanging on gh auth login.
  Inside the container:
  - gh auth status → ✓ Logged in as alliepiper
  - git status → On branch devcontainer-worktree-fix (no
  "dubious ownership" error)
  - git rev-parse --git-dir →
  /home/allie/code/src/cccl/.git/worktrees/devcontainer-worktree-fix
  - git rev-parse --git-common-dir → /home/allie/code/src/cccl/.git
  - git log resolves commits correctly.

[alliepiper]

"the devcontainer"

I'm a human I swear.

[coderabbitai]

📝 Walkthrough

Summary by CodeRabbit

• Chores
  • Enhanced dev container launch script to support Git worktree configurations, enabling improved Git operations within containers
  • Added automatic detection and mounting of shared Git configuration for worktree setups
  • Improved authentication handling to prevent unnecessary interactive login flows
  • Added warnings for potential artifact conflicts when running concurrent dev containers from linked worktrees

Walkthrough

The devcontainer launch script now detects when running from a Git worktree, computes the shared Git directory, and bind-mounts it into the container. It also conditionally mounts shared auth config and emits warnings about shared Docker volumes.

Changes

Devcontainer Git Worktree Integration

Layer / File(s)	Summary
Git worktree detection and Docker mount configuration .devcontainer/launch.sh	Worktree detection checks if .git is a file, computes the shared Git common directory, and bind-mounts it. Optional .config/gh auth config is also mounted. Multi-line warnings inform users about shared Docker volumes and potential artifact collisions between concurrent worktree containers.

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[coderabbitai]

Actionable comments posted: 1

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: 418c5a4d-63cc-455e-9cb4-76401d30f28e

📥 Commits

Reviewing files that changed from the base of the PR and between e49bdfa and 78a9efa.

📒 Files selected for processing (1)

• .devcontainer/launch.sh

[github-actions]

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