[macOS][Onboard] Colima onboarding fails to start the gateway: Socket not found /var/run/docker.sock #12367

Investigation Summary

• Preflight passes, then the gateway fails to start with Socket not found: /var/run/docker.sock.
• Colima exposes Docker through the colima context and does not create /var/run/docker.sock. The gateway reads only DOCKER_HOST.
• detectDockerHost keeps the reachable CLI default, so DOCKER_HOST is never set. This regressed after fix(cli): preserve healthy Docker authority #8823; fix(platform): detect Colima docker.sock at top-level path (#3503) #3505 had fixed it for [macOS][Onboard] nemoclaw onboard fails on Colima — openshell-gateway hardcodes /var/run/docker.sock, ignores DOCKER_HOST #3503.
• Workaround: export DOCKER_HOST=unix://$HOME/.colima/default/docker.sock.

Description

nemoclaw onboard fails at [2/8] Starting OpenShell gateway on macOS with Colima and DOCKER_HOST unset.

Expected: the gateway uses the Docker daemon that preflight found.

Reproduction Steps

1. brew install colima docker && colima start --cpu 4 --memory 8
2. Confirm DOCKER_HOST is unset, docker context show prints colima, and /var/run/docker.sock does not exist.
3. Run nemoclaw onboard.

Environment

• OS: macOS 26.6.2 (Apple M4)
• Container runtime: Colima 0.10.3, Docker 29.5.2
• Node.js: v22.23.3
• OpenShell: 0.0.116
• NemoClaw: main at 586438d93

Debug Output

  [1/8] Preflight checks
  ✓ Docker daemon: server 29.5.2
  ✓ Container runtime: colima

  [2/8] Starting OpenShell gateway
  Docker-driver gateway failed to start.
    Error:   × execution error: failed to create compute runtime: execution error: failed
      │ to create Docker client: Socket not found: /var/run/docker.sock
  Docker daemon is not running — cannot start the gateway.