docker context use/build proxy not work, due the "docker.example.com" hard code!

Description

spark@MacBook-Pro ~ % docker context ls
NAME DESCRIPTION DOCKER ENDPOINT ERROR
remotesrv * ssh://user1@xxxxxxx.com

spark@MacBook-Pro ~ % cat ~/.docker/config.json
{
"proxies": {
"http://docker.example.com": { <<=== only "http://docker.example.com" working!!!!
"httpProxy": "http://172.17.0.1:10800",
"httpsProxy": "http://172.17.0.1:10800",
"noProxy": "localhost,127.0.0.1"
}
},
"currentContext": "alisrv"
}

{
"proxies": {
"any others will not work!!!!!": {

long time, the bug is there!

Reproduce

docker context create / use
docker context ls
docker build .

Expected behavior

No response

docker version

Client:
 Version:           29.4.0
 API version:       1.54
 Go version:        go1.25.5
 Git commit:        9d7ad9f
 Built:             unknown-buildtime
 OS/Arch:           darwin/arm64
 Context:           alisrv

Server: Docker Engine - Community
 Engine:
  Version:          29.5.0
  API version:      1.54 (minimum version 1.40)
  Go version:       go1.26.3
  Git commit:       ff8d90a
  Built:            Thu May 14 14:40:34 2026
  OS/Arch:          linux/amd64
  Experimental:     false
 containerd:
  Version:          v2.2.3
  GitCommit:        77c84241c7cbdd9b4eca2591793e3d4f4317c590
 runc:
  Version:          1.3.5
  GitCommit:        v1.3.5-0-g488fc13e
 docker-init:
  Version:          0.19.0
  GitCommit:        de40ad0

docker info

Client:
 Version:    29.4.0
 Context:    alisrv
 Debug Mode: false
 Plugins:
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.33.0
    Path:     /Users/spark/.docker/cli-plugins/docker-buildx
  compose: Docker Compose (Docker Inc.)
    Version:  v5.1.2
    Path:     /Users/spark/.docker/cli-plugins/docker-compose

Server:
 Containers: 6
  Running: 2
  Paused: 0
  Stopped: 4
 Images: 8
 Server Version: 29.5.0
 Storage Driver: overlayfs
  driver-type: io.containerd.snapshotter.v1
 Logging Driver: json-file
 Cgroup Driver: systemd
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local splunk syslog
 CDI spec directories:
  /etc/cdi
  /var/run/cdi
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 77c84241c7cbdd9b4eca2591793e3d4f4317c590
 runc version: v1.3.5-0-g488fc13e
 init version: de40ad0
 Security Options:
  apparmor
  seccomp
   Profile: builtin
  cgroupns
 Kernel Version: 6.12.88+deb13-amd64
 Operating System: Debian GNU/Linux 13 (trixie)
 OSType: linux
 Architecture: x86_64
 CPUs: 2
 Total Memory: 1.848GiB
 Name: alisrv
 ID: 743bebd6-450a-4011-983c-f5218f627cc0
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 HTTP Proxy: http://172.17.0.1:10800
 HTTPS Proxy: http://172.17.0.1:10800
 No Proxy: localhost,127.0.0.1
 Experimental: false
 Insecure Registries:
  ::1/128
  127.0.0.0/8
 Live Restore Enabled: false
 Firewall Backend: iptables
  EnableUserlandProxy: true
  UserlandProxyPath: /usr/bin/docker-proxy

Additional Info

No response

Start by reproducing the behavior with docker context create, docker context use, docker context ls, and docker build ., using a proxy key other than http://docker.example.com. Trace the Docker CLI context and proxy handling to locate the hard-coded endpoint. Done means proxy settings apply to the active context's actual endpoint and the behavior is covered by an appropriate test.