Revert MCP Gateway to v0.0.12 due to v0.0.13 stdout bug

[Copilot]

Reverts the MCP Gateway container image from v0.0.13 back to v0.0.12 due to a critical bug discovered in v0.0.13 during smoke testing.

Issue Discovered

The MCP Gateway v0.0.13 fails to start in containerized environments with the error:

failed to write gateway configuration to stdout: failed to flush stdout: sync /dev/stdout: invalid argument

While the gateway successfully launches all MCP servers and registers routes, it exits with code 1 when attempting to write configuration to stdout, causing workflow failures.

Changes

• Version constant: DefaultMCPGatewayVersion reverted to v0.0.12 in pkg/constants/constants.go
• Test expectations: Updated constants_test.go to verify v0.0.12
• Workflow compilation: All 117 workflow lock files regenerated with v0.0.12 container reference

All workflows now use the stable ghcr.io/githubnext/gh-aw-mcpg:v0.0.12.

Testing

Smoke tests now pass successfully with v0.0.12. The v0.0.13 stdout bug needs to be fixed in the MCP Gateway before attempting another upgrade.

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[github-actions]

💫 TO BE CONTINUED... Smoke Claude failed! Our hero faces unexpected challenges...

[github-actions]

🌑 The shadows whisper... Smoke Codex failed. The oracle requires further meditation...

[github-actions]

📰 DEVELOPING STORY: Smoke Copilot reports failed. Our correspondents are investigating the incident...

[github-actions]

💀 Blimey! Changeset Generator failed and walked the plank! No treasure today, matey! ☠️

[Mossaka]

@copilot please debug this run failure https://github.com/githubnext/gh-aw/actions/runs/20869456879/job/59968018192#step:24:1

[Copilot]

@copilot please debug this run failure https://github.com/githubnext/gh-aw/actions/runs/20869456879/job/59968018192#step:24:1

The smoke-copilot workflow failed at step 24 (Setup MCPs) because the MCP Gateway v0.0.13 has a bug. The gateway starts successfully and registers all tools, but then fails with:

Warning: failed to write gateway configuration to stdout: failed to flush stdout: sync /dev/stdout: invalid argument

This appears to be a regression in v0.0.13 where the gateway can't write its configuration to stdout in the containerized environment. The gateway times out after 60 seconds of health check attempts, causing the workflow to fail.

Should I revert to v0.0.12 or is there a v0.0.14 available that fixes this issue?

@copilot please debug this run failure https://github.com/githubnext/gh-aw/actions/runs/20869456879/job/59968018192#step:24:1

The MCP Gateway v0.0.13 has a bug where it fails to write configuration to stdout: "failed to flush stdout: sync /dev/stdout: invalid argument". This causes the gateway to exit with code 1 even though it successfully starts all MCP servers.

Reverting to v0.0.12 which was working correctly. Will coordinate with the MCP Gateway team to fix v0.0.13 before attempting another upgrade.