Overview

Architectural review identified several structural issues affecting maintainability, testability, and idiomatic Rust compliance. This epic tracks all findings as a cohesive improvement effort.

Child Issues

Positive Findings

• Crate dependency graph is acyclic with clean domain boundaries
• Native async traits (Edition 2024) used consistently in core traits
• Feature gates are additive-only and correctly structured
• Error handling: thiserror in library crates, typed error enums with good coverage

Acceptance Criteria

• Agent struct decomposed into focused sub-structs (Decompose Agent struct: extract ProviderState, SessionState, UiState, OrchestrationState #1731)
• anyhow removed from zeph-core (Remove anyhow from zeph-core library crate #1732)
• config/types.rs split into domain modules (Split config/types.rs into domain-specific config modules #1735)
• semantic.rs split into sub-modules (Split semantic.rs into recall, summarization, and cross-session sub-modules #1736)
• LoopbackEvent large variants boxed (Box large LoopbackEvent variants to reduce enum size #1737)
• async-trait removed from search_code.rs (Replace async-trait with native async traits in zeph-tools/search_code.rs #1733)
• clippy::too_many_lines suppressions reduced (Reduce clippy::too_many_lines suppressions in agent module #1734)
• All CI checks pass: cargo +nightly fmt --check, cargo clippy --workspace --features full -- -D warnings, cargo nextest run --workspace --features full --lib --bins

Notes

• Pre-v1.0.0: no backward compatibility required, clean rewrites preferred
• Each child issue should be a separate PR on its own branch (feat/mXX/arch-*)