diff --git a/CLAUDE.md b/CLAUDE.md
index b2258b2..5e70545 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -1,56 +1,123 @@
+---
+description: Agent instructions for the subtrack monorepo
+---
+
 # subtrack
 
 Monorepo for **subtrack** — a CLI tool to manage subscription services from the terminal.
 
+## Agent Role
+
+You are a subtrack agent. Your primary responsibilities in this repository are:
+
+- Understanding the full monorepo structure and how packages relate
+- Implementing features and fixing bugs in the CLI tool (`subtrack/`)
+- Maintaining code quality, type safety, and test coverage
+- Following project conventions (ESM, TypeScript strict, `sql.js`, `gunshi`)
+- Knowing when to load project-specific skills for detailed guidance
+
 ## Repository Structure
 
 ```
 .
-├── subtrack/        # CLI tool (Node.js/TypeScript, published as npm package)
-├── docs/            # Documentation site (SvelteKit)
-├── .agents/         # OpenCode agent and skill definitions
-├── flake.nix        # Nix devShell / CI shell
+├── subtrack/          # CLI tool (Node.js/TypeScript, published as npm package)
+│   ├── src/           # Source code
+│   ├── dist/          # Build output (dist/index.mjs)
+│   ├── package.json   # Dependencies and scripts
+│   └── tsconfig.json  # TypeScript configuration
+├── docs/              # Documentation site (SvelteKit)
+├── .agents/skills/    # OpenCode skill definitions
+├── flake.nix          # Nix devShell / CI shell
 └── pnpm-workspace.yaml
 ```
 
-## Package Management
+**Key**: All application code lives under `subtrack/`. The monorepo root has no dependencies of its own.
+
+## Design Tenets
+
+1. **CLI-native** — Everything is driven from the terminal. No web UI, no daemon, no TUI framework.
+2. **SQLite persistence** — Data is stored locally via `sql.js` (WASM SQLite). No external database servers.
+3. **Layer separation** — Code is organized into strict layers (entry → commands → DB → display). Cross-layer concerns are mediated, not mixed.
+4. **Interactive by default, scriptable by flag** — Commands prompt interactively when invoked bare, but accept flags for automation.
+5. **Portable** — Works on Linux/macOS. Single binary via npm package. No platform-specific dependencies.
+
+## Architecture Overview
 
-- Use `pnpm add <package>` instead of `npm install <package>` or `bun add <package>`
-- Use `pnpm remove <package>` instead of `npm uninstall <package>` or `bun remove <package>`
-- Use `pnpm update` instead of `npm update` or `bun update`
-- Use `pnpm run <script>` or `pnpm <script>` instead of `npm run` or `bun run`
-- Use `pnpmx <package>` instead of `npx` or `bunx`
+The CLI tool (`subtrack/`) uses `gunshi` for command routing and follows a multi-layer architecture:
 
-## Root Commands
+| Layer       | File                | Responsibility                      |
+| ----------- | ------------------- | ----------------------------------- |
+| Entry       | `src/index.ts`      | Command definitions (gunshi), routing |
+| Commands    | `src/commands.ts`   | Command handlers, workflow logic    |
+| Database    | `src/db.ts`         | SQLite CRUD, schema, persistence    |
+| Display     | `src/display.ts`    | Table rendering, formatting         |
+| Prompts     | `src/prompts.ts`    | Input validation, interactive prompts |
+| Payment     | `src/payment.ts`    | Payment/summary calculations        |
+| FX          | `src/fx.ts`         | Exchange rate fetching & conversion |
+| Usage       | `src/usage.ts`      | LLM API usage tracking              |
+
+For **detailed implementation guidance** (DB schema, testing patterns, import style, dependency reference), load the `subtrack-rules` skill.
+
+## Available Skills
+
+This repository defines skills under `.agents/skills/`. Load them via the `skill` tool when the task matches:
+
+| Skill | When to load |
+|---|---|
+| `subtrack-rules` | Working on source code, running tests, managing dependencies — full project conventions |
+| `subtrack-commit` | Committing, pushing, or creating a PR |
+| `bug-fixes` | Diagnosing test failures, debugging runtime errors, fixing type errors |
+
+All 3 skills are also available automatically via the agent system prompt.
+
+## Key Conventions
+
+- **Runtime**: Node.js (>=22), **not** Bun or Deno
+- **Language**: TypeScript (strict mode, ESM, `verbatimModuleSyntax`)
+- **Database**: `sql.js` (SQLite via WASM) — **not** `better-sqlite3` or `bun:sqlite`
+- **CLI**: `gunshi` — **not** `commander` (despite what old docs may say)
+- **Package manager**: `pnpm` — **not** npm or bun
+- **Local imports**: use `.ts` extension (`import { x } from "./foo.ts"`)
+- **Node built-ins**: use `node:` prefix (`node:fs`, `node:path`, `node:os`)
+- **Type imports**: use `type` prefix (`import type { X } from "./foo.ts"`)
+- **No semicolons** in imports/exports
+- **Prices**: stored as integers (smallest unit — JPY no decimal, USD in cents)
+- **DB transactions**: use `BEGIN TRANSACTION` / `COMMIT` / `ROLLBACK` for multi-step writes
+- **PRAGMA**: `PRAGMA foreign_keys = ON` at connection time
+
+## Quick Reference
 
 ```bash
 pnpm install          # install all workspace dependencies
 pnpm build            # build all packages (pnpm -r build)
 pnpm test             # test all packages (pnpm -r test)
-```
-
-## Nix DevShell
-
-```bash
-nix develop           # enter devShell (node, pnpm, typos, typescript, nixfmt)
+pnpm start            # run CLI in dev mode (tsx src/index.ts)
+nix develop           # enter devShell
 nix fmt               # format nix files (nixfmt-rfc-style)
 ```
 
-## Key Conventions
+Available CLI commands (run `subtrack --help` in the package for the full list):
 
-- **Runtime**: Node.js, **NOT** Bun or Deno
-- **Language**: TypeScript (strict mode, ESM, `verbatimModuleSyntax`)
-- **Database**: `sql.js` (SQLite via WASM), **NOT** `better-sqlite3` or `bun:sqlite`
-- **Node built-ins**: Use `node:` prefix (`node:fs`, `node:path`, `node:os`)
-- **Local imports**: Use `.ts` extension (`import { x } from "./foo.ts"`)
-- **Type imports**: Use `type` prefix (`import type { X } from "./foo.ts"`)
-- **No semicolons** in imports/exports
-- **API**: Prefer native `fetch` for HTTP, native `WebSocket` for WebSocket
+| Command | Description |
+|---|---|
+| `subtrack list` | List all subscriptions |
+| `subtrack add` | Add a subscription |
+| `subtrack edit [id]` | Edit a subscription |
+| `subtrack delete [ids...]` | Delete subscriptions |
+| `subtrack tags <names...>` | Filter by tags (AND logic) |
+| `subtrack tag list\|rename\|delete\|prune` | Manage tags |
+| `subtrack export csv\|json\|md` | Export subscriptions |
+| `subtrack import <file>` | Import from CSV |
+| `subtrack summary` | Show subscription summary |
+| `subtrack backup [destination]` | Backup database |
+| `subtrack restore [file]` | Restore database |
+| `subtrack payment [period]` | Show payment totals |
+| `subtrack usage add\|list\|delete\|refresh` | Track LLM API usage |
 
 ## Environment Variables
 
-| Variable           | Description                                       |
-| ------------------ | ------------------------------------------------- |
+| Variable | Description |
+|---|---|
 | `SUBSC_CLI_DB_DIR` | Override database directory (default: `~/.config/subtrack`) |
 
 ## Links
diff --git a/subtrack/CLAUDE.md b/subtrack/CLAUDE.md
index 587dd6f..bc33548 100644
--- a/subtrack/CLAUDE.md
+++ b/subtrack/CLAUDE.md
@@ -4,13 +4,14 @@ CLI tool to manage subscription services from the terminal. Node.js + TypeScript
 
 ## Tech Stack
 
-- **Runtime**: Node.js (not Bun or Deno)
+- **Runtime**: Node.js (>=22, not Bun or Deno)
 - **Language**: TypeScript (strict mode, ESM, `verbatimModuleSyntax`)
 - **Database**: `sql.js` (SQLite via WASM)
-- **CLI**: `commander`
+- **CLI**: `gunshi`
 - **Prompts**: `@inquirer/prompts`
 - **Logging**: `consola`
 - **Tables**: `cli-table3`
+- **Colors**: `picocolors`
 - **Build**: `tsdown`
 - **Test**: `vitest`
 
@@ -36,15 +37,23 @@ CLI tool to manage subscription services from the terminal. Node.js + TypeScript
 - Mock `consola` via `consola.mockTypes()`
 - Mock `globalThis.fetch` for FX rate API
 
-## Architecture (4 layers)
+## Architecture
 
-| Layer | File | Responsibility |
-|---|---|---|
-| Entry | `src/index.ts` | CLI definition (commander), command routing |
-| Commands | `src/commands.ts` | Command handlers, workflow logic |
-| Database | `src/db.ts` | SQLite CRUD, schema, persistence |
-| Display | `src/display.ts` | Table rendering, FX rate conversion |
-| Prompts | `src/prompts.ts` | Input validation, interactive prompts |
+| File | Responsibility |
+|---|---|
+| `src/index.ts` | CLI definition (gunshi), command routing |
+| `src/commands.ts` | Command handlers, workflow logic |
+| `src/db.ts` | SQLite CRUD, schema, persistence |
+| `src/display.ts` | Table rendering, formatting |
+| `src/prompts.ts` | Input validation, interactive prompts |
+| `src/payment.ts` | Payment/summary calculations |
+| `src/fx.ts` | Exchange rate fetching & conversion |
+| `src/usage.ts` | LLM API usage tracking |
+| `src/export.ts` | CSV/JSON/MD export |
+| `src/import-csv.ts` | CSV import |
+| `src/crypto.ts` | Backup encryption |
+| `src/pricing.ts` | Pricing/litellm integration |
+| `src/types.ts` | Shared types |
 
 ## Key Conventions
 
@@ -53,7 +62,6 @@ CLI tool to manage subscription services from the terminal. Node.js + TypeScript
 - **Type imports**: `type` prefix (`import type { X } from "./foo.ts"`)
 - **No semicolons** in imports/exports
 - **Prices**: integers (smallest unit — JPY no decimal, USD cents)
-- **Cycles**: weekly / bi-weekly / monthly / quarterly / semi-annual / yearly
 - **DB**: `sql.js` with `PRAGMA foreign_keys = ON`, use transactions for multi-step writes
 
 ## Environment Variables
@@ -68,8 +76,14 @@ CLI tool to manage subscription services from the terminal. Node.js + TypeScript
 |---|---|
 | `subtrack list` | List all subscriptions |
 | `subtrack add` | Add a subscription |
-| `subtrack delete` | Delete subscriptions (interactive) |
-| `subtrack tags <taglist...>` | Filter by tags |
-| `subtrack backup <destination>` | Backup database |
+| `subtrack edit [id]` | Edit a subscription |
+| `subtrack delete [ids...]` | Delete subscriptions |
+| `subtrack tags <names...>` | Filter by tags (AND logic) |
+| `subtrack tag list\|rename\|delete\|prune` | Manage tags |
+| `subtrack export csv\|json\|md` | Export subscriptions |
+| `subtrack import <file>` | Import from CSV |
+| `subtrack summary` | Show subscription summary |
+| `subtrack backup [destination]` | Backup database |
+| `subtrack restore [file]` | Restore database |
 | `subtrack payment [period]` | Show payment totals |
-| `subtrack export csv` | Export subscriptions as CSV |
+| `subtrack usage add\|list\|delete\|refresh` | Track LLM API usage |