Problem

Multiple opportunities exist to leverage Rust's type system more aggressively:

• Unnecessary dyn Trait usage where static dispatch suffices
• Runtime type checks (type_name) duplicated across 3 LLM providers
• No compile-time enforcement of Agent state boundaries
• Boolean flag state machines instead of proper enums
• Duplicated BoxFuture type aliases

Goal

Improve type safety, reduce dynamic dispatch overhead, and make invalid states unrepresentable.

Audit Reference

.local/audit/002-type-safety-opportunities.md

Key Issues

• TYPE-01: Replace unnecessary dyn Trait with static dispatch (3 locations)
• TYPE-02: Consolidate BoxFuture type alias (3 definitions)
• TYPE-03: Extract shared type_name schema helper for LLM providers
• TYPE-04: Agent state accessor boundaries (long-term)
• TYPE-05: Type-state pattern for Agent lifecycle (evaluation)
• TYPE-06: Compaction enum state machine (replace boolean flags)
• TYPE-07..09: GAT evaluation for VectorStore and ToolExecutor

Acceptance Criteria

• No unnecessary Box in hot paths
• Single BoxFuture definition shared across zeph-memory
• Shared schema_prompt helper in zeph-llm
• CompactionState enum replaces 4 boolean flags
• All tests pass