Desktop users need a direct way to pick an installed Agent from slash completion while preserving the existing command and skill namespace. Add /agent <agent> <prompt> as the single execution surface and render active agents as namespaced completion rows.
Constraint: Existing slash command names and ordering must remain authoritative.
Rejected: Register each Agent as a top-level /<agent> command | would collide with built-in commands, skills, and future custom commands.
Confidence: high
Scope-risk: moderate
Tested: bun run verify
