Incorporated the earlier proposed validation change here and preserved co-author credit in the commit.

Greptile Summary

This PR tightens gateway startup validation by making trusted-proxy mode and a shared token mutually exclusive, and removes the runtime loopback token-fallback path that created the ambiguity in the first place. The two concerns are addressed together: assertGatewayAuthConfigured now throws at server startup if both are present, and authorizeGatewayConnect no longer silently falls back to token auth for loopback requests. Test coverage is thorough — the parameterised it.each covers both the gateway.auth.token config path and the OPENCLAW_GATEWAY_TOKEN environment path, and a dedicated ordering test confirms that a missing trustedProxy config error still takes precedence over the token-conflict error.

Key changes:

• auth.ts:325–329: mutual-exclusion guard added inside the trusted-proxy branch of assertGatewayAuthConfigured
• auth.ts:460–479: ~24 lines of loopback token-fallback logic removed from authorizeGatewayConnect; all loopback requests now uniformly return trusted_proxy_loopback_source
• auth.test.ts: local-direct describe block renamed; four previously passing token-fallback assertions updated to expect rejection; new startup-validation tests added

Confidence Score: 5/5

Safe to merge — no correctness issues remain; the mutual-exclusion guard is correct and the removal of the loopback fallback is consistent with the new policy.

All P1 concerns from prior review threads have been resolved: the startup validator now correctly rejects mixed configs, the loopback fallback code has been fully removed (eliminating the false-confidence from the old token-fallback tests), and the new ordering test confirms the trustedProxy presence guard still fires before the token-conflict guard. No new logic bugs or security gaps were identified in this pass.

No files require special attention.

_{Reviews (2): Last reviewed commit: "Gateway: fail closed for loopback truste..." | Re-trigger Greptile}

@greptile review