# EdgeFEM Project Review — Sprint Health Check

## Overview
This review cross-references the committed implementation against the project plan to highlight accomplished scope, gaps, and recommended next steps.

## What is Working Today
- **Scalar & vector formulations**: The repository ships scalar and Maxwell solvers with lumped port support, frequency sweeps, and demos that generate Touchstone files and plots, matching Sprint 0/1 milestones. Assembly covers curl–curl, mass matrices, PEC handling, and optional ABC/PML stubs.【F:project_plan.md†L33-L118】【F:src/assemble_maxwell.cpp†L1-L103】【F:src/waveguide_demo.cpp†L1-L48】【F:examples/plot_waveguide_sparams.py†L1-L37】
- **Port infrastructure (partial)**: A 2D generalized eigen solve exists for port cross-sections and validates WR-90 cutoff frequencies via tests, covering part of Sprint 2.【F:project_plan.md†L120-L156】【F:src/ports/port_eigensolve.cpp†L1-L118】【F:tests/test_ports.cpp†L1-L39】
- **Tooling & docs**: The README documents build steps, demos, and macOS guidance per Sprint 0 deliverables, and test targets exist for PML, sweeps, and near-to-far conversions.【F:project_plan.md†L52-L98】【F:README.md†L1-L73】【F:tests/CMakeLists.txt†L1-L47】

## Gaps Against the Plan
- **Sprint 2 completion**: Modal normalization and coupling into the 3D assembly remain unimplemented; the generalized eigen solver only returns cutoff frequencies without field profiles or power normalization. Touchstone generation depends on lumped-edge ports rather than surface excitations.【F:project_plan.md†L132-L156】【F:src/ports/port_eigensolve.cpp†L1-L118】
- **Radiation & PML maturity**: PML handling is currently a uniform stretch scalar with manual region tags and lacks diagnostics or stability checks outlined for Sprint 3. No ABC fallback controls beyond a simple diagonal damping term.【F:project_plan.md†L158-L188】【F:src/assemble_maxwell.cpp†L14-L90】
- **Sweeps/MOR & adaptive backlog**: Frequency sweep logic is direct looping without reuse or vector fitting, and there is no adaptive mesh refinement infrastructure. MOR, HPC, Python SDK, and GUI sprints are untouched, which is expected but important for roadmap sequencing.【F:project_plan.md†L190-L286】【F:src/sweep.cpp†L1-L119】

## Recommended Next Steps
1. **Finish Sprint 2 deliverables**
   - Extend `solve_port_eigens` to return field vectors and modal impedances using area integrals; build power normalization utilities and integrate them into `assemble_maxwell` so that wave ports replace lumped-edge excitations.【F:project_plan.md†L132-L152】【F:src/ports/port_eigensolve.cpp†L65-L118】
   - Implement regression tests that drive `calculate_sparams` with modal ports against analytic WR-90 S-parameters to unlock the remaining acceptance criteria.【F:project_plan.md†L148-L156】
2. **Stabilize open-boundary treatments (Sprint 3)**
   - Introduce per-direction PML stretch tensors, enforce sigma grading heuristics, and surface diagnostics (reflection estimates) before enabling by default. Add ABC unit tests using manufactured plane-wave absorption.【F:project_plan.md†L158-L186】【F:src/assemble_maxwell.cpp†L18-L90】
3. **Lay groundwork for sweeps and adaptive roadmap (Sprints 4–6)**
   - Refactor sweep execution into a reusable driver that captures Krylov seeds and logs runtime, paving the way for MOR hooks. Begin designing data structures for per-element error indicators to avoid rework when adaptive refinement starts.【F:project_plan.md†L190-L242】【F:src/sweep.cpp†L1-L119】
4. **Documentation & release hygiene**
   - Mirror plan progress in README/CHANGELOG, and script CI smoke tests (waveguide demo + port eigen test) to maintain visibility as new features land.【F:project_plan.md†L41-L98】【F:README.md†L1-L73】【F:tests/test_ports.cpp†L1-L39】

## Risks & Watchouts
- Port coupling accuracy will bottleneck validation; prioritize numerical conditioning (mass matrix scaling) to avoid noisy S-parameters.【F:src/ports/port_eigensolve.cpp†L65-L118】
- PML instability could degrade solver convergence—monitor residual histories once graded stretches are introduced.【F:src/assemble_maxwell.cpp†L18-L90】

