Maintainability Review - Pick'n'Play

A) Current focus

This document tracks only active work. Completed work is intentionally omitted and can be reviewed in git history.

Active maintainability risks (priority order):

wwwroot/js/ui.js remains the dominant hotspot and owns rendering, modal flows, admin flows, and vote logic.
Cross-feature coupling still exists via shared mutable state usage across UI/data modules (wwwroot/js/ui.js:180, wwwroot/js/ui.js:401, wwwroot/js/ui.js:622, wwwroot/js/data.js:82).
Impact: high regression surface and expensive refactors even after removing global window bridges.

Reveal is still present in Domain/Phase.cs:6 and compatibility branches remain in Endpoints/StateEndpoints.cs:102 and Endpoints/StateEndpoints.cs:111.
Impact: extra cognitive load and more branches to reason about during phase-flow changes.

Endpoint and filter unauthorized responses are standardized when app logic executes (Infrastructure/AdminOnlyFilter.cs:15, Infrastructure/PhaseRequirementFilter.cs:15, Endpoints/SuggestEndpoints.cs:18), but anonymous challenge responses remain middleware-controlled (GameList.Tests/StateTests.cs:214).
Impact: clients must tolerate both app-produced problem payloads and framework challenge responses.

CI currently gates restore/build/test only (.github/workflows/ci.yml:23-.github/workflows/ci.yml:29).
Impact: style drift and low-signal warnings can enter the codebase undetected.

[P1] Decompose frontend UI monolith by feature

Problem: Severity High, Category Architecture/Complexity. ui.js still mixes rendering, form behavior, and mutation flows.
Evidence: wwwroot/js/ui.js:180, wwwroot/js/ui.js:401, wwwroot/js/ui.js:622, wwwroot/js/ui.js:903, wwwroot/js/data.js:82.
Recommendation: split by feature (suggestions-ui, votes-ui, admin-ui, modals-ui) and keep orchestration in a thin composition layer.
Acceptance criteria (testable): UI behavior is preserved while feature modules own isolated responsibilities and no single file coordinates all vote/admin/modal/suggestion interactions.
Effort / Risk: L / Med.
Dependencies (if any): none.

[P1] Remove legacy Reveal phase compatibility branches

Problem: Severity Medium, Category Complexity. Legacy phase compatibility logic is still present in runtime paths.
Evidence: Domain/Phase.cs:6, Endpoints/StateEndpoints.cs:102, Endpoints/StateEndpoints.cs:111, wwwroot/js/data.js:30.
Recommendation: remove Reveal from enum/transition logic and update affected tests/documentation.
Acceptance criteria (testable): no runtime references to Phase.Reveal; phase transitions cover only Suggest, Vote, and Results.
Effort / Risk: S / Low.
Dependencies (if any): none.

[P1] Unify client handling of unauthenticated 401 challenge responses

Problem: Severity Medium, Category API/Contracts. Fully unauthenticated requests can still bypass application-level problem shaping.
Evidence: challenge behavior is exercised in GameList.Tests/StateTests.cs:214 while app-level unauthorized shaping is exercised in GameList.Tests/AuthTests.cs:164.
Recommendation: either customize cookie-auth challenge response to RFC7807 or explicitly codify dual-shape handling contract in API docs and frontend error layer.
Acceptance criteria (testable): single documented 401 contract path, with tests validating response shape and frontend behavior.
Effort / Risk: M / Med.
Dependencies (if any): none.

[P2] Add static analysis and JS lint/format guardrails

Problem: Severity Medium, Category Tooling. CI does not enforce analyzers or JS lint/format checks.
Evidence: .github/workflows/ci.yml:23-.github/workflows/ci.yml:29.
Recommendation: add .NET analyzer configuration and ESLint/Prettier checks, then enforce in CI.
Acceptance criteria (testable): CI fails on analyzer/lint violations; local scripts are documented in root docs.
Effort / Risk: M / Low.
Dependencies (if any): none.

[P2] Externalize i18n and FAQ content from executable JS

Problem: Severity Low, Category Complexity/Documentation. Translation and FAQ payloads are embedded in code.
Evidence: wwwroot/js/i18n.js:1-wwwroot/js/i18n.js:799.
Recommendation: move language dictionaries and FAQ markdown into versioned data assets with schema checks.
Acceptance criteria (testable): i18n.js holds behavior only; assets load and render identical user-facing text.
Effort / Risk: M / Low.
Dependencies (if any): frontend module split is helpful but optional.

Keep endpoint handlers transport-focused and move business rules into services/validators.
Keep reads side-effect free and isolate all persistence changes to explicit command paths.
Maintain one source of truth per validation rule (backend authoritative, frontend UX hints only).
Prefer typed DTOs over anonymous response shapes for non-trivial API payloads.