Keep failed trace reads separate from compatibility verdicts #259

🤖 Generated by the Agentic Engineer

The reader accepts a missing or cross-namespace producer edge carrying a compatible contract verdict even though those paths never inspect the producer.

Audience: product authors and consumers using the portable browser hosts. This is a reproducible client behavior gap in the current released implementation; preserve public metadata, independent product ownership and existing access boundaries.

Reproduction: Supply a missing or rejected cross-namespace edge with compatibility marked compatible.

Acceptance: Failures that prevent producer inspection require not-evaluated compatibility; valid evaluated edges followed by traversal timeout, depth limits or explicit cycles remain supported. Preserve existing release gates and include failing-then-passing browser regressions, current-head review and release verification.

Part of #1. Rough size: S.