Dev Containers: reconnecting to existing subfolder config container fails with "devcontainer.json not found"

VS Code version: 1.116.0
Dev Containers extension: 0.454.0
Connection type: Containers
Host OS: macOS darwin/arm64
Remote OS: linux/arm64 (Docker Desktop 4.67.0 / Docker Engine 29.3.1)

Description

When a dev container was originally created from a subfolder config, reconnecting
to the container — whether it is running or stopped — fails with:

Error: Dev container config (.devcontainer/devcontainer.json) not found.

Reproduced with all extensions disabled.

Reproducible steps

1. Create a workspace folder with the following structure — no root-level devcontainer.json:

   .devcontainer/
     node/
       devcontainer.json
       Dockerfile
     python/
       devcontainer.json
       Dockerfile
   

2. Run "Dev Containers: Open Folder in Container...", select either the node
   or python config when prompted — container builds and connects successfully.
3. Disconnect (close window, hibernate, or set "shutdownAction": "stopContainer").
4. Attempt to reconnect via "Reopen in Container" or by reopening the folder in VS Code.

Expected behaviour

The extension reconnects to (or restarts) the existing container using the same
config it was originally built from.

Actual behaviour

The CLI is invoked without --config, so it falls back to looking for
.devcontainer/devcontainer.json at the root, which does not exist. Exit code 1.

Root cause (identified)

The stopped container already has the correct config path recorded in its label:

"devcontainer.config_file": "/path/to/.devcontainer/python/devcontainer.json"

The extension reads this label to locate the container (via
docker ps --filter label=devcontainer.local_folder=...) but does not subsequently
pass --config <devcontainer.config_file> when invoking the CLI up command.

CLI invocation (actual):

devContainersSpecCLI.js up \
  --workspace-folder /path/to/repo \
  --id-label devcontainer.local_folder=/path/to/repo \
  --skip-post-create ...

CLI invocation (expected):

devContainersSpecCLI.js up \
  --workspace-folder /path/to/repo \
  --config /path/to/repo/.devcontainer/python/devcontainer.json \
  --id-label devcontainer.local_folder=/path/to/repo \
  --skip-post-create ...

Workaround

Use "Dev Containers: Open Folder in Container..." and re-select the config each
time. This command correctly passes --config to the CLI and does not trigger
a rebuild — it finds the existing stopped container by its labels, starts it, and attaches.