Fast Jev Compaction

# MISSION: Scaffold "Fast Jev Compaction" Production Architecture
You are an expert Senior Staff Software Architect and Full-Stack Engineer. Your mission is to scaffold and implement a production-grade, highly reliable, and modular codebase following the proven architecture of **Fast Jev Compaction**.
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## 1. PROJECT SPECIFICATIONS & BENCHMARK
- **Reference Architecture**: Fast Jev Compaction
- **What It Does**: Fast Jev Compaction is a Claude Code plugin and npm library that compacts long agent sessions by asking TypeSafe's Jev which tool calls and results to keep, drop or truncate, instead of summarizing them with an LLM.
- **Domain & Category**: Claude Code Plugin
- **Production Scale**: Solo
- **Development Mode**: CLASSIC
- **Architectural Rationale**: Two Jev Noul questions per tool call, gated by a threshold in code, prune a transcript without rewriting it, and a thin hook adapter falls back to Claude Code's built-in summary whenever Jev fails or saves too little.
- **Live Website Reference**: https://github.com/tamaratran/fast-jev-compaction
- **Source Repository**: https://github.com/tamaratran/fast-jev-compaction
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## 2. PRODUCTION TECH STACK
- **Full Stack Array**: TypeScript, Node.js, Jev, Claude Code, Vitest
- **Primary Language(s)**: TypeScript
- **License of the reference repo**: MIT
- **Backend & APIs**: TypeScript — npm library in src/ (ESM, Node 18+) with no runtime dependencies; compiled with tsc.; Native fetch — Calls the System One endpoint directly through an injectable fetch, with request building and response validation in src/request.ts.
- **Infrastructure & deploy**: Vitest — Unit tests for the library and the hook adapter.
- **Tooling, testing & ops**: Jev — Answers two Noul questions per tool call: keep the call, and keep the result verbatim.; Claude Code — Function-hook plugin (hooks/fast-jev.ts) that replaces the built-in compaction summary, falling back to it on errors.
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## 3. KEY ARCHITECTURAL DECISIONS (audited from https://github.com/tamaratran/fast-jev-compaction @ e3f262a)
1. **Delete instead of summarize**: The README explains that LLM summaries are lossy, so the library never rewrites anything: it only removes tool calls and tool results that Jev judges no longer needed, and user and assistant text stays verbatim and in order.
2. **Two Noul questions per tool call**: For every non-pinned call, Jev answers whether the call itself still matters and whether its result must stay verbatim. Against keepThreshold (0.5 by default) code keeps both, keeps the call with a truncated result, or removes the pair, so the decision logic is ordinary code around two probabilities.
3. **Fit the state in code, in stages**: State is the whole conversation with tool results replaced by short notes. It is fitted under maxStateTokens (25k by default) by successively truncating tool inputs, abridging long texts and collapsing old messages, and questions are batched so each request stays under maxRequestTokens (30k), below Jev's 32k limit.
4. **Library first, plugin as a thin adapter**: src/ is an npm package with a pluggable JevAsker transport and exported building blocks (collectToolCalls, fitState, batchCalls, decideCall, applyDecisions); hooks/fast-jev.ts is a thin Claude Code function hook that uses it and falls back to the built-in summary when reduction is too small or Jev fails.
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## 4. NON-NEGOTIABLE ARCHITECTURAL GUARDRAILS
1. **Monorepo & Modular Separation**:
   - Structure as a Turborepo monorepo with strict package boundaries:
     - `apps/web`: Application UI, routing, layouts, and server endpoints.
     - `packages/ui`: Shared design tokens, CSS variables, and Radix UI primitive components.
     - `packages/db`: Database schemas, client singleton, declarative migrations, and seed scripts.
     - `packages/config`: Shared TypeScript, ESLint, and build configurations.
2. **Strict Type Safety & Zero `any` Policy**:
   - Enable `strict: true`, `noImplicitAny: true`, and `strictNullChecks: true`.
   - Validate ALL external inputs, API request bodies, and query parameters with **Zod** schemas before execution.
3. **Frontend & Rendering Guidelines**:
   - Utilize Vite 6 with TanStack Router for fully type-safe routing. Manage server state and caching via TanStack Query v5 with optimistic UI updates.
4. **Design System & Aesthetics**:
   - Keep every color, radius, shadow and font in a single token file (CSS variables) and consume tokens everywhere; never hardcode hex values in components.
   - Prefer crisp 1px borders and one subtle shadow scale over blurry default shadows. Pair one sans-serif for body/headings with one monospace for tags, badges, metrics, and code.
5. **Data Layer & Reliability**:
   - Write declarative schema definitions with foreign keys, composite indexes on queried filters, and automated timestamp triggers.
   - Use connection pooling and prepared statements for serverless database execution.
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## 5. STEP-BY-STEP SCAFFOLDING ROADMAP
- **Phase 1: Workspace & Root Config**: Initialize package manager, monorepo configuration (`turbo.json`, `tsconfig.base.json`, `package.json`).
- **Phase 2: Database Schema & Client**: Set up the data layer: client, connection pool, models, and migration scripts.
- **Phase 3: Design Tokens & UI Primitives**: Build accessible `Button`, `Input`, `Card`, `Badge`, and layout wrappers inside `packages/ui`.
- **Phase 4: Core Application Routes & Handlers**: Implement primary authentication, user session handling, and application routes.
- **Phase 5: Quality Assurance & Build Verification**: Run `tsc --noEmit`, ESLint, Prettier, and smoke test suites to ensure zero compilation or runtime errors.
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## 6. EXECUTION INSTRUCTIONS
1. Review all specifications, architectural guardrails, and stack choices above.
2. Present the full monorepo directory tree structure.
3. Systematically generate the complete, production-ready codebase according to the 5-phase roadmap above — starting with the root workspace setup, followed by the database schema, UI design system package, and full-stack application routes until the repository is fully scaffolded and ready to run.