Problem observed

Toolset selection logic supports both default and explicit toolset names, but overlap scenarios need a hard contract for deterministic resolution and ordering. Without explicit regression coverage, subtle future changes could alter enabled toolset ordering or emitted tool order, causing behavior churn for clients that depend on stable capability composition.

Why it matters operationally

Deterministic toolset resolution is critical for predictable capability exposure and auditability. Order instability can produce noisy diffs, inconsistent host behavior, and harder policy verification when tool availability changes unexpectedly between equivalent configurations. A focused test strengthens confidence without changing runtime code paths.

Minimal repro