[BUG] Build fails when two services share a build context with a Chinese directory path

[ANTIQUE91]

Description

When two or more services in a docker-compose file share the same build.context pointing to a directory whose path contains non-ASCII characters (e.g., Chinese characters), docker compose up -d fails with a gRPC internal error during the build phase.
The error does not occur when:

• Only one service uses that build context
• Two services share a build context with an ASCII-only path
  This suggests a bug in BuildKit's gRPC session key serialization when multiple concurrent builds reference the same non-ASCII path.

Steps To Reproduce

Use this ZIP to reproduce the bug --> test.zip <--

Compose Version

Docker Compose version v5.1.4

Docker Environment

PS E:\Users\ANTIK\Downloads\test(1)> docker info
Client:
 Version:    29.5.3
 Context:    desktop-linux
 Debug Mode: false
 Plugins:
  agent: Docker AI Agent Runner (Docker Inc.)
    Version:  v1.79.0
    Path:     C:\Program Files\Docker\cli-plugins\docker-agent.exe
  ai: Docker AI Agent - Ask Gordon (Docker Inc.)
    Version:  v1.25.0
    Path:     C:\Program Files\Docker\cli-plugins\docker-ai.exe
  buildx: Docker Buildx (Docker Inc.)
    Version:  v0.34.1-desktop.1
    Path:     C:\Program Files\Docker\cli-plugins\docker-buildx.exe
  compose: Docker Compose (Docker Inc.)
    Version:  v5.1.4
    Path:     C:\Program Files\Docker\cli-plugins\docker-compose.exe
  debug: Get a shell into any image or container (Docker Inc.)
    Version:  0.0.47
    Path:     C:\Program Files\Docker\cli-plugins\docker-debug.exe
  desktop: Docker Desktop commands (Docker Inc.)
    Version:  v0.4.1
    Path:     C:\Program Files\Docker\cli-plugins\docker-desktop.exe
  dhi: CLI for managing Docker Hardened Images (Docker Inc.)
    Version:  v0.0.4
    Path:     C:\Program Files\Docker\cli-plugins\docker-dhi.exe
  extension: Manages Docker extensions (Docker Inc.)
    Version:  v0.2.31
    Path:     C:\Program Files\Docker\cli-plugins\docker-extension.exe
  init: Creates Docker-related starter files for your project (Docker Inc.)
    Version:  v1.4.0
    Path:     C:\Program Files\Docker\cli-plugins\docker-init.exe
  mcp: Docker MCP Plugin (Docker Inc.)
    Version:  v0.42.2
    Path:     C:\Program Files\Docker\cli-plugins\docker-mcp.exe
  model: Docker Model Runner (Docker Inc.)
    Version:  v1.2.1
    Path:     C:\Program Files\Docker\cli-plugins\docker-model.exe
  offload: Docker Offload (Docker Inc.)
    Version:  v0.6.4
    Path:     C:\Program Files\Docker\cli-plugins\docker-offload.exe
  pass: Docker Pass Secrets Manager Plugin (beta) (Docker Inc.)
    Version:  v0.1.5
    Path:     C:\Program Files\Docker\cli-plugins\docker-pass.exe
  sandbox: Docker Sandbox (Docker Inc.)
    Version:  v0.12.0
    Path:     C:\Program Files\Docker\cli-plugins\docker-sandbox.exe
  scout: Docker Scout (Docker Inc.)
    Version:  v1.21.0
    Path:     C:\Program Files\Docker\cli-plugins\docker-scout.exe

Server:
 Containers: 3
  Running: 2
  Paused: 0
  Stopped: 1
 Images: 12
 Server Version: 29.5.3
 Storage Driver: overlayfs
  driver-type: io.containerd.snapshotter.v1
 Logging Driver: json-file
 Cgroup Driver: cgroupfs
 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
 Discovered Devices:
  cdi: docker.com/gpu=webgpu
 Swarm: inactive
 Runtimes: nvidia runc io.containerd.runc.v2
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: e53c7c1516c3b2bff98eb76f1f4117477e6f4e66
 runc version: v1.3.6-0-g491b69ba
 init version: de40ad0
 Security Options:
  seccomp
   Profile: builtin
  cgroupns
 Kernel Version: 6.18.33.1-microsoft-standard-WSL2
 Operating System: Docker Desktop
 OSType: linux
 Architecture: x86_64
 CPUs: 24
 Total Memory: 7.752GiB
 Name: docker-desktop
 ID: 652a6346-c7e0-4f11-93b4-e604bd7c0e5f
 Docker Root Dir: /var/lib/docker
 Debug Mode: false
 HTTP Proxy: http.docker.internal:3128
 HTTPS Proxy: http.docker.internal:3128
 No Proxy: hubproxy.docker.internal
 Labels:
  com.docker.desktop.address=npipe://\\.\pipe\docker_cli
 Experimental: false
 Insecure Registries:
  hubproxy.docker.internal:5555
  127.0.0.0/8
  ::1/128
 Registry Mirrors:
  https://docker.m.daocloud.io/
  https://docker.1panel.live/
  https://hub.rat.dev/
  https://docker.xuanyuan.me/
  https://docker.lms.run/
  https://dockerproxy.net/
  https://hub.uuuadc.top/
 Live Restore Enabled: false
 Firewall Backend: iptables

Anything else?

test.zip

[maxproske]

Thanks for your report! This is an upstream buildkit issue I was able to reproduce. PR incoming.