Add MCP Gateway build steps to language-support-tester workflow

[Copilot]

The Language Support Tester workflow failed because it referenced the registry image ghcr.io/github/gh-aw-mcpg without building it locally first, causing Docker daemon connectivity issues and missing Serena MCP tools.

Changes

Added local container build steps following the smoke-copilot.md pattern:

• Docker Buildx setup - Added docker/setup-buildx-action@v3 step
• Local MCP Gateway build - Builds local-awmg:v0.1.4 with embedded awmg binary
• Container reference - Updated sandbox.mcp.container from ghcr.io/github/gh-aw-mcpg to local-awmg

steps:
  - name: Set up Docker Buildx
    uses: docker/setup-buildx-action@v3
  - name: Build local MCP Gateway container
    run: |
      VERSION="dev-$(git rev-parse --short HEAD)"
      docker build -t local-awmg:v0.1.4 --build-arg VERSION=${VERSION} .

sandbox:
  mcp:
    container: "local-awmg"  # Changed from registry reference

This ensures the MCP Gateway is available without external registry dependencies, enabling Serena tools (activate_project, find_symbols, etc.) for Go, TypeScript/JavaScript, and Python language testing.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• https://api.github.com/repos/docker/setup-buildx-action/git/ref/tags/v3
  • Triggering command: /usr/bin/gh gh api /repos/docker/setup-buildx-action/git/ref/tags/v3 --jq .object.sha (http block)
• https://api.github.com/repos/github/gh-aw/git/ref/tags/v0.46.1
  • Triggering command: /usr/bin/gh gh api /repos/github/gh-aw/git/ref/tags/v0.46.1 --jq .object.sha (http block)
• https://api.github.com/user
  • Triggering command: /usr/bin/gh gh api user --jq .login -main/dist/indexuser.name (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

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This section details on the original issue you should resolve

<issue_title>[language-support] Serena MCP server tools unavailable — language support tests could not run</issue_title>
<issue_description>## Summary

The Language Support Tester workflow (run #34, run ID 22164360544) could not complete language support testing for Go, TypeScript/JavaScript, and Python because the Serena MCP server tools were not available in the sandbox environment.

Failure Details

Root Cause

The Docker daemon is not accessible from within the sandbox container:

Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

Because Docker is unavailable, the Serena MCP server container (ghcr.io/github/serena-mcp-server:latest) cannot be started. As a result, none of the language server tools (activate_project, find_symbols, get_definition, etc.) were present in the agent's available tool list.

Diagnostic evidence

• /tmp/gh-aw/mcp-logs/ — empty (no MCP server logs, no tools.json)
• /tmp/gh-aw/mcp-config/ — contains only jq-error.log, no MCP configuration JSON files
• docker images / docker ps — command fails: daemon not reachable
• awmg binary — not found in PATH
• Serena tools (activate_project, find_symbols, etc.) — absent from agent function-call interface

Languages affected

Language	Status
Go	❌ Not tested — Serena unavailable
TypeScript/JavaScript	❌ Not tested — Serena unavailable
Python	❌ Not tested — Serena unavailable

Steps to Reproduce

1. Trigger the Language Support Tester workflow
2. Observe that no Serena MCP tools appear in the agent's available tools
3. docker ps inside the sandbox returns a daemon connection error

Expected Behavior

• Serena MCP server starts successfully
• activate_project, find_symbols, get_definition tools are available
• Language support is verified for Go, TypeScript/JavaScript, and Python

Suggested Investigation

• Verify that the sandbox container has access to the Docker daemon (Docker-in-Docker or DooD)
• Confirm the workflow's tools: serena: configuration is correctly translating into MCP server setup
• Check whether the pre-pull step (docker pull ghcr.io/github/serena-mcp-server:latest) is succeeding before the agent starts

Generated by Language Support Tester

• expires on Feb 26, 2026, 1:14 AM UTC

Comments on the Issue (you are @copilot in this section)

• Fixes [language-support] Serena MCP server tools unavailable — language support tests could not run #1088

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[Copilot]

Pull request overview

Updates the Language Support Tester agentic workflow to build the MCP Gateway container locally and run the sandbox against that local image, avoiding reliance on the GHCR gh-aw-mcpg image and improving workflow reliability for Serena-based language support testing.

Changes:

• Added Docker Buildx setup and a local docker build step producing local-awmg:v0.1.4.
• Switched sandbox.mcp.container from ghcr.io/github/gh-aw-mcpg to local-awmg.
• Updated the compiled lock workflow to preload and run local-awmg:v0.1.4 (including the gateway run command).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
.github/workflows/language-support-tester.md	Adds local MCP Gateway image build steps and points the sandbox container to local-awmg.
.github/workflows/language-support-tester.lock.yml	Recompiled workflow reflecting the new build steps and switching the gateway image to local-awmg:v0.1.4.

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