fix: don't use Gateway.Domain in gateway output URLs

[lpcox]

Problem

The smoke-allowonly workflow fails with Ping failed: HTTP 000 on all MCP server connectivity checks when using gateway v0.1.12+.

Root cause: Commit 9a70098 added logic to prefer cfg.Gateway.Domain (e.g., host.docker.internal) in writeGatewayConfig output URLs. The gateway output config is consumed by the gh-aw infrastructure's connectivity check script, which runs on the host runner. host.docker.internal doesn't resolve from the host, causing curl to get no TCP connection (HTTP 000).

Evidence:

• v0.1.8 (success): gateway output URLs used http://0.0.0.0:80/mcp/* → curl treats as localhost → works
• v0.1.12 (failure): gateway output URLs used http://host.docker.internal:80/mcp/* → DNS fails from host → HTTP 000
• Health check on localhost:80 always passes — the gateway IS running
• Gateway logs show zero MCP requests in failing runs (requests never reach the gateway)

Fix

Remove the cfg.Gateway.Domain preference from writeGatewayConfig. The gateway output should always use the listen host (with wildcard addresses mapped to 127.0.0.1). The downstream converter already handles domain mapping when generating agent configs for container-side access.

Changes

• internal/cmd/root.go: Remove domain preference, keep wildcard→127.0.0.1 mapping
• internal/cmd/stdout_config_test.go: Update test expectations
• test/integration/auth_config_test.go: Update URL expectation

All tests pass (make agent-finished ✓).

[Copilot]

Pull request overview

Fixes gateway stdout “output config” URL generation to be host-runner reachable by avoiding cfg.Gateway.Domain (e.g., host.docker.internal) and instead using the listen host with wildcard binds mapped to 127.0.0.1. This aligns the gateway’s emitted config with how gh-aw host-side connectivity checks consume it.

Changes:

• Update writeGatewayConfig to always derive output URLs from the listen host (wildcard → 127.0.0.1), ignoring cfg.Gateway.Domain.
• Adjust unit test expectations for domain vs. listen-host behavior.
• Update integration test expectation for emitted routed URL host.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
internal/cmd/root.go	Stops preferring cfg.Gateway.Domain for stdout output URLs; keeps wildcard → 127.0.0.1 mapping.
internal/cmd/stdout_config_test.go	Updates test case naming/expectations to reflect domain no longer overriding listen host.
test/integration/auth_config_test.go	Updates expected routed URL host to 127.0.0.1 to match new output behavior.

Comments suppressed due to low confidence (1)

internal/cmd/root.go:454

• The debug log "Resolved gateway address" logs host, but the URLs are built using domain (which may be rewritten from wildcard hosts to 127.0.0.1). This can be misleading when troubleshooting output URL issues; consider logging domain (or both host and domain) here.

	domain := host
	if domain == "0.0.0.0" || domain == "::" || domain == "[::]" {
		domain = "127.0.0.1"
	}

	debugLog.Printf("Resolved gateway address: host=%s, port=%s", host, port)

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