# claude-usage-widget

A small always-on-top Windows desktop widget that visualizes your local Claude Code usage:

- **Current 5-hour session block** — progress ring + countdown to block end.
- **Past 7 days** — daily bars + total.
- **Per-model breakdown** — Opus / Sonnet / Haiku stacked across the current block.

Reads `~/.claude/projects/**/*.jsonl` directly. No Anthropic API. No auth.

```
┌────────────── Claude Usage ───────╳ ─┐
│                                       │
│            ╭─────╮                    │
│           ╱       ╲                   │
│          │  47k    │   ← 5-hour block │
│          │  24%    │                  │
│           ╲ 3h 12m╱                   │
│            ╰─────╯                    │
│                                       │
│   Models (current block)              │
│   ▰▰▰▰▰▰▰▰▱▱▱▱▱▱▱▱                    │
│   ● Opus 32k   ● Sonnet 11k           │
│                                       │
│   7-day total      842k · 42%         │
│   ▁▃▆█▂▅▇                             │
│   Sat Sun Mon Tue Wed Thu Fri         │
└───────────────────────────────────────┘
```

## What this is *not*

It does not call the Anthropic API and cannot show server-side ground-truth caps. The "5-hour" and "weekly" numbers are derived from your local JSONL transcripts — the same data `ccusage` operates on. The cap values shown in the percentage and the warning thresholds are user-configurable in Settings.

## Architecture (one paragraph)

A Tauri 2 app with a Rust backend and a Svelte 5 + Vite + TS frontend. The Rust side enumerates `~/.claude/projects/**/*.jsonl`, tail-parses each file (resuming from a cached byte offset so we never re-parse already-seen lines), dedupes events by `requestId || uuid` (subagent transcripts overlap parents), aggregates into 5-hour blocks (ccusage-equivalent algorithm: `block_start = floor_to_hour(first_ts)`, `block_end = block_start + 5h`, new block on ≥5h gap or end-of-block), computes a rolling 7-day window in the user's local timezone, and emits a `usage-updated` event whenever anything changes. A `notify-debouncer-full` watcher fires on file changes; a 60s `tokio::time::interval` poll backstops it because `ReadDirectoryChangesW` on the WSL `\\wsl$\` 9P mount can miss events. The widget window is frameless, transparent, `alwaysOnTop`, `skipTaskbar`, and 280×360 px; drag via the custom title bar.

## Build & run

You need a **Windows** host with the Tauri 2 toolchain — see [Tauri prerequisites](https://v2.tauri.app/start/prerequisites/). Quick version:

```powershell
winget install Rustlang.Rustup OpenJS.NodeJS.LTS
rustup default stable-x86_64-pc-windows-msvc
npm i -g pnpm
# Also: MSVC C++ Build Tools + Windows SDK (Visual Studio Installer),
#       and Microsoft Edge WebView2 Runtime (preinstalled on Windows 11).
```

Then, from this directory:

```powershell
pnpm install
pnpm tauri dev          # iterate
pnpm tauri build        # NSIS installer in src-tauri\target\release\bundle\nsis\
```

If you're developing in WSL but building on Windows, the WSL filesystem is mounted at `\\wsl$\<distro>\` from Windows; clone or copy this folder onto the Windows side (or work directly via the UNC path) before running `pnpm tauri build` — Tauri itself needs the MSVC linker.

> **Icons.** Before `pnpm tauri build` succeeds, drop a 1024×1024 PNG into `src-tauri/icons/source.png` and run `pnpm tauri icon src-tauri/icons/source.png` to generate every required size.

## Configuration

`%APPDATA%\claude-widget\config.json` (auto-created on first run):

```jsonc
{
  "caps": {
    "block_tokens": 200000,    // 5h block cap — placeholder default
    "weekly_tokens": 2000000   // 7d weekly cap — placeholder default
  },
  "wsl_distro_override": null, // null = autodetect via `wsl.exe -l -q`
  "include_native": true,      // also scan %USERPROFILE%\.claude\projects
  "window_pos": null,
  "autostart": false
}
```

Everything except `window_pos` is editable in the in-app Settings panel (gear icon).

## Verification checklist

1. **Cold parse correctness** — compare `BlockRing` total to:
   ```bash
   jq -s '[.[]|select(.type=="assistant")|.message.usage|(.input_tokens+.output_tokens+.cache_creation_input_tokens+.cache_read_input_tokens)]|add' \
     ~/.claude/projects/<path>/<sessionId>.jsonl
   ```
2. **Block boundary** — `scripts\seed-fake-jsonl.ps1 -OffsetHours -6` appends a back-dated synthetic line; confirm it produces a *new* prior block instead of folding into the active one.
3. **Dedupe** — duplicate one assistant line into the matching `subagents/<id>.jsonl`; total must not double.
4. **Live tail** — start a real `claude` session in WSL; the ring should tick up within a couple of seconds (debouncer ~250 ms).
5. **Watcher fallback** — set `WIDGET_NO_WATCH=1` in the env (TODO: wire this up if needed) and append a line; the next 60s poll picks it up.
6. **Fake feed** — `scripts\seed-fake-jsonl.ps1` writes a synthetic assistant line; UI updates without restart.
7. **WSL detection** — switch `wsl_distro_override` in Settings to a distro with no `.claude/`; snapshot goes empty.
8. **Autostart** — toggle on, reboot, confirm widget appears (Task Manager → Startup tab); toggle off, reboot, confirm it doesn't.
9. **Transparency / drag** — no chrome; title-bar drag moves the window; position survives restart.
10. **Memory ceiling** — 24h soak, expect 40–80 MB RSS.

## Files of interest

| File | Purpose |
|---|---|
| `src-tauri/src/jsonl.rs`   | Streaming parse + model normalization + dedupe key |
| `src-tauri/src/usage.rs`   | 5-hour blocks, weekly window, snapshot builder (incl. unit tests) |
| `src-tauri/src/watch.rs`   | `notify` debouncer + 60s poll fallback + emit |
| `src-tauri/src/paths.rs`   | WSL detection, `\\wsl$\…` UNC path resolution |
| `src-tauri/src/commands.rs`| Tauri `#[command]` IPC surface |
| `src-tauri/tauri.conf.json`| Frameless / transparent / always-on-top window config |
| `src/components/*.svelte`  | UI |

## License

Private project. Not published.