initial commit

2026-06-08 22:49:50 -07:00
commit f6a6681e16
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@@ -0,0 +1,7 @@
+.venv/
+__pycache__/
+*.pyc
+.DS_Store
+frontend/node_modules/
+frontend/dist/
+uv.lock
@@ -0,0 +1 @@
+3.9
@@ -0,0 +1,90 @@
+# sfxkeeb
+
+Annotate keyboard key presses on a video timeline and preview/export mechanical switch sounds mixed with the video audio.
+
+## Requirements
+
+- [uv](https://docs.astral.sh/uv/) (Python package manager)
+- Node.js 18+ and npm
+- **ffmpeg** on your PATH (required by pydub for audio export)
+
+```bash
+# macOS
+brew install ffmpeg
+```
+
+## Setup
+
+```bash
+# Python dependencies
+uv sync
+
+# Frontend dependencies
+cd frontend && npm install
+```
+
+## Development
+
+Run both servers in separate terminals:
+
+```bash
+# Terminal 1 — FastAPI backend (audio export API)
+uv run uvicorn backend.main:app --reload
+
+# Terminal 2 — Vite dev server (proxies /api to :8000)
+cd frontend && npm run dev
+```
+
+Open http://localhost:5173
+
+## Production-like run
+
+```bash
+cd frontend && npm run build
+uv run uvicorn backend.main:app --host 127.0.0.1 --port 8000
+```
+
+Open http://127.0.0.1:8000
+
+## Usage
+
+1. **Open Video** — load an MP4 file
+2. Press keys while the playhead is at the desired time to add markers (works while playing or paused)
+3. Select markers to override keys, nudge with arrow keys, or multi-select with marquee drag
+4. Choose a mechanical switch sound from the dropdown
+5. **Save Project** / **Open Project** — JSON with version, markers, and switch setting (no video path)
+6. **Export Audio** — download a WAV file of keyboard sounds only, full video length
+
+### Keyboard shortcuts
+
+| Shortcut | Action |
+|----------|--------|
+| Ctrl+Space | Play / pause |
+| Arrow keys | Nudge selected marker(s) one frame |
+| Alt+Scroll | Zoom timeline (centers on playhead) |
+| Backspace / Delete | Delete selected marker(s) |
+| Ctrl+A | Select all markers |
+
+## Project file format
+
+```json
+{
+  "version": 1,
+  "switch": "cherry-mx-blue",
+  "markers": [
+    { "id": "m1", "time": 1.234, "key": "a" }
+  ]
+}
+```
+
+Re-open the video manually after loading a project file.
+
+## Switch samples
+
+Bundled samples are short synthetic click sounds representing Cherry MX Blue (clicky), Red (linear), and Brown (tactile) switches.
+
+## Known limitations
+
+- Frame stepping uses `video.currentTime` and may land on nearest keyframes for some MP4 encodings
+- Project files do not reference the video file path
+- Very long videos may take longer to export via pydub in-memory overlay
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+import io
+from pathlib import Path
+
+from pydub import AudioSegment
+
+from backend.models import ExportRequest, SwitchType
+
+SAMPLE_RATE = 48000
+SAMPLES_DIR = Path(__file__).resolve().parent.parent / "assets" / "samples"
+
+SWITCH_FILES: dict[SwitchType, str] = {
+    "cherry-mx-blue": "cherry-mx-blue.wav",
+    "cherry-mx-red": "cherry-mx-red.wav",
+    "cherry-mx-brown": "cherry-mx-brown.wav",
+}
+
+
+def _load_sample(switch: SwitchType) -> AudioSegment:
+    path = SAMPLES_DIR / SWITCH_FILES[switch]
+    if not path.exists():
+        raise FileNotFoundError(f"Sample not found: {path}")
+    sample = AudioSegment.from_file(path)
+    return sample.set_frame_rate(SAMPLE_RATE).set_channels(2)
+
+
+def export_keyboard_audio(request: ExportRequest) -> bytes:
+    duration_ms = int(request.duration * 1000)
+    base = AudioSegment.silent(duration=duration_ms, frame_rate=SAMPLE_RATE)
+    click = _load_sample(request.switch)
+
+    for marker in sorted(request.markers, key=lambda m: m.time):
+        position_ms = int(marker.time * 1000)
+        if position_ms < duration_ms:
+            base = base.overlay(click, position=position_ms)
+
+    buffer = io.BytesIO()
+    base.export(buffer, format="wav")
+    return buffer.getvalue()
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+from pathlib import Path
+
+import uvicorn
+from fastapi import FastAPI, HTTPException
+from fastapi.middleware.cors import CORSMiddleware
+from fastapi.responses import Response
+from fastapi.staticfiles import StaticFiles
+
+from backend.audio_export import export_keyboard_audio
+from backend.models import ExportRequest
+
+ROOT = Path(__file__).resolve().parent.parent
+DIST = ROOT / "frontend" / "dist"
+ASSETS = ROOT / "assets"
+
+app = FastAPI(title="sfxkeeb")
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["http://localhost:5173", "http://127.0.0.1:5173"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+if ASSETS.exists():
+    app.mount("/assets", StaticFiles(directory=ASSETS), name="assets")
+
+
+@app.post("/api/export/audio")
+def export_audio(request: ExportRequest) -> Response:
+    try:
+        wav_bytes = export_keyboard_audio(request)
+    except FileNotFoundError as exc:
+        raise HTTPException(status_code=500, detail=str(exc)) from exc
+    except Exception as exc:
+        raise HTTPException(status_code=500, detail=f"Export failed: {exc}") from exc
+
+    return Response(
+        content=wav_bytes,
+        media_type="audio/wav",
+        headers={"Content-Disposition": 'attachment; filename="keyboard_track.wav"'},
+    )
+
+
+@app.get("/api/health")
+def health() -> dict[str, str]:
+    return {"status": "ok"}
+
+
+if DIST.exists():
+    app.mount("/", StaticFiles(directory=DIST, html=True), name="frontend")
+
+
+def run() -> None:
+    uvicorn.run("backend.main:app", host="127.0.0.1", port=8000, reload=True)
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+from typing import Literal
+
+from pydantic import BaseModel, Field
+
+SwitchType = Literal["cherry-mx-blue", "cherry-mx-red", "cherry-mx-brown"]
+
+
+class Marker(BaseModel):
+    id: str
+    time: float = Field(ge=0)
+    key: str
+
+
+class Project(BaseModel):
+    version: int = 1
+    switch: SwitchType = "cherry-mx-blue"
+    markers: list[Marker] = Field(default_factory=list)
+
+
+class ExportRequest(BaseModel):
+    duration: float = Field(gt=0)
+    switch: SwitchType = "cherry-mx-blue"
+    markers: list[Marker] = Field(default_factory=list)
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+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+lerna-debug.log*
+
+node_modules
+dist
+dist-ssr
+*.local
+
+# Editor directories and files
+.vscode/*
+!.vscode/extensions.json
+.idea
+.DS_Store
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?
@@ -0,0 +1,3 @@
+{
+  "recommendations": ["svelte.svelte-vscode"]
+}
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+# Svelte + TS + Vite
+
+This template should help get you started developing with Svelte and TypeScript in Vite.
+
+## Recommended IDE Setup
+
+[VS Code](https://code.visualstudio.com/) + [Svelte](https://marketplace.visualstudio.com/items?itemName=svelte.svelte-vscode).
+
+## Need an official Svelte framework?
+
+Check out [SvelteKit](https://github.com/sveltejs/kit#readme), which is also powered by Vite. Deploy anywhere with its serverless-first approach and adapt to various platforms, with out of the box support for TypeScript, SCSS, and Less, and easily-added support for mdsvex, GraphQL, PostCSS, Tailwind CSS, and more.
+
+## Technical considerations
+
+**Why use this over SvelteKit?**
+
+- It brings its own routing solution which might not be preferable for some users.
+- It is first and foremost a framework that just happens to use Vite under the hood, not a Vite app.
+
+This template contains as little as possible to get started with Vite + TypeScript + Svelte, while taking into account the developer experience with regards to HMR and intellisense. It demonstrates capabilities on par with the other `create-vite` templates and is a good starting point for beginners dipping their toes into a Vite + Svelte project.
+
+Should you later need the extended capabilities and extensibility provided by SvelteKit, the template has been structured similarly to SvelteKit so that it is easy to migrate.
+
+**Why `global.d.ts` instead of `compilerOptions.types` inside `jsconfig.json` or `tsconfig.json`?**
+
+Setting `compilerOptions.types` shuts out all other types not explicitly listed in the configuration. Using triple-slash references keeps the default TypeScript setting of accepting type information from the entire workspace, while also adding `svelte` and `vite/client` type information.
+
+**Why include `.vscode/extensions.json`?**
+
+Other templates indirectly recommend extensions via the README, but this file allows VS Code to prompt the user to install the recommended extension upon opening the project.
+
+**Why enable `allowJs` in the TS template?**
+
+While `allowJs: false` would indeed prevent the use of `.js` files in the project, it does not prevent the use of JavaScript syntax in `.svelte` files. In addition, it would force `checkJs: false`, bringing the worst of both worlds: not being able to guarantee the entire codebase is TypeScript, and also having worse typechecking for the existing JavaScript. In addition, there are valid use cases in which a mixed codebase may be relevant.
+
+**Why is HMR not preserving my local component state?**
+
+HMR state preservation comes with a number of gotchas! It has been disabled by default in both `svelte-hmr` and `@sveltejs/vite-plugin-svelte` due to its often surprising behavior. You can read the details [here](https://github.com/rixo/svelte-hmr#svelte-hmr).
+
+If you have state that's important to retain within a component, consider creating an external store which would not be replaced by HMR.
+
+```ts
+// store.ts
+// An extremely simple external store
+import { writable } from 'svelte/store'
+export default writable(0)
+```
@@ -0,0 +1,13 @@
+<!doctype html>
+<html lang="en">
+  <head>
+    <meta charset="UTF-8" />
+    <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <title>sfxkeeb</title>
+  </head>
+  <body>
+    <div id="app"></div>
+    <script type="module" src="/src/main.ts"></script>
+  </body>
+</html>
@@ -0,0 +1,21 @@
+{
+  "name": "frontend",
+  "private": true,
+  "version": "0.0.0",
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "preview": "vite preview",
+    "check": "svelte-check --tsconfig ./tsconfig.app.json && tsc -p tsconfig.node.json"
+  },
+  "devDependencies": {
+    "@sveltejs/vite-plugin-svelte": "^7.1.2",
+    "@tsconfig/svelte": "^5.0.8",
+    "@types/node": "^24.12.3",
+    "svelte": "^5.55.5",
+    "svelte-check": "^4.4.8",
+    "typescript": "~6.0.2",
+    "vite": "^8.0.12"
+  }
+}
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+</svg>
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+<script lang="ts">
+  import { onDestroy, onMount } from 'svelte';
+  import { createAudioEngine } from './lib/audio/engine';
+  import {
+    isEditableTarget,
+    keyLabel,
+    shouldOverrideSelected,
+    shouldRecordMarker,
+  } from './lib/keyboard';
+  import { downloadProject, exportAudio, loadProject } from './lib/project';
+  import {
+    addMarker,
+    app,
+    deleteMarkers,
+    nudgeSelected,
+    selectAll,
+    setActiveSwitch,
+    setFps,
+    setVideoUrl,
+    snapToFrame,
+    updateMarker,
+  } from './lib/store.svelte';
+  import Timeline from './lib/timeline/Timeline.svelte';
+  import { SWITCH_OPTIONS } from './lib/types';
+  import { attachVideoPlayer, type VideoController } from './lib/video/player';
+
+  let videoEl: HTMLVideoElement | undefined = $state();
+  let videoInput: HTMLInputElement | undefined = $state();
+  let projectInput: HTMLInputElement | undefined = $state();
+  let controller: VideoController | null = null;
+  let audioEngine = createAudioEngine();
+  let statusMessage = $state('');
+  let lastScheduledTime = -1;
+
+  function rescheduleAudio() {
+    if (!videoEl) return;
+    audioEngine.reschedule(videoEl.currentTime, app.markers, !videoEl.paused);
+    lastScheduledTime = videoEl.currentTime;
+  }
+
+  function initVideo() {
+    if (!videoEl) return;
+    controller?.destroy();
+    void audioEngine.init(videoEl).then(() => rescheduleAudio());
+    controller = attachVideoPlayer(videoEl);
+  }
+
+  $effect(() => {
+    if (app.videoUrl && videoEl) initVideo();
+  });
+
+  $effect(() => {
+    if (!videoEl) return;
+    const t = app.currentTime;
+    const playing = app.isPlaying;
+    void app.markers;
+    void app.activeSwitch;
+    if (playing && Math.abs(t - lastScheduledTime) > 0.25) {
+      rescheduleAudio();
+    }
+  });
+
+  onMount(() => {
+    const onKeyDown = (event: KeyboardEvent) => {
+      if (isEditableTarget(event.target)) return;
+
+      if (event.ctrlKey && event.code === 'Space') {
+        event.preventDefault();
+        controller?.togglePlayPause();
+        rescheduleAudio();
+        return;
+      }
+
+      if ((event.ctrlKey || event.metaKey) && event.key.toLowerCase() === 'a') {
+        event.preventDefault();
+        selectAll();
+        return;
+      }
+
+      if (event.key === 'Backspace' || event.key === 'Delete') {
+        if (app.selectedIds.size > 0) {
+          event.preventDefault();
+          deleteMarkers(new Set(app.selectedIds));
+          rescheduleAudio();
+        }
+        return;
+      }
+
+      if (['ArrowLeft', 'ArrowRight'].includes(event.key) && app.selectedIds.size > 0) {
+        event.preventDefault();
+        nudgeSelected(event.key === 'ArrowLeft' ? -1 : 1);
+        rescheduleAudio();
+        return;
+      }
+
+      if (shouldOverrideSelected(event, app.selectedIds.size > 0)) {
+        const label = keyLabel(event);
+        if (!label) return;
+        event.preventDefault();
+        for (const id of app.selectedIds) updateMarker(id, { key: label });
+        return;
+      }
+
+      if (!app.videoUrl || !videoEl) return;
+
+      if (shouldRecordMarker(event)) {
+        const label = keyLabel(event);
+        if (!label) return;
+        event.preventDefault();
+        const time = snapToFrame(videoEl.currentTime);
+        addMarker(time, label);
+        rescheduleAudio();
+      }
+    };
+
+    window.addEventListener('keydown', onKeyDown);
+    return () => window.removeEventListener('keydown', onKeyDown);
+  });
+
+  onDestroy(() => {
+    controller?.destroy();
+    audioEngine.destroy();
+  });
+
+  async function handleVideoFile(event: Event) {
+    const input = event.target as HTMLInputElement;
+    const file = input.files?.[0];
+    if (!file) return;
+    setVideoUrl(URL.createObjectURL(file), file.name);
+    statusMessage = `Loaded video: ${file.name}`;
+    input.value = '';
+  }
+
+  async function handleProjectFile(event: Event) {
+    const input = event.target as HTMLInputElement;
+    const file = input.files?.[0];
+    if (!file) return;
+    try {
+      const text = await file.text();
+      loadProject(JSON.parse(text));
+      statusMessage = `Loaded project: ${file.name}`;
+      rescheduleAudio();
+    } catch (error) {
+      statusMessage = error instanceof Error ? error.message : 'Failed to load project';
+    }
+    input.value = '';
+  }
+
+  async function handleExportAudio() {
+    if (!app.duration) {
+      statusMessage = 'Load a video before exporting audio';
+      return;
+    }
+    try {
+      statusMessage = 'Exporting audio...';
+      await exportAudio(app.duration);
+      statusMessage = 'Audio export complete';
+    } catch (error) {
+      statusMessage = error instanceof Error ? error.message : 'Export failed';
+    }
+  }
+</script>
+
+<div class="app">
+  <header class="toolbar">
+    <div class="file-actions">
+      <button type="button" onclick={() => videoInput?.click()}>Open Video</button>
+      <button type="button" onclick={() => projectInput?.click()}>Open Project</button>
+      <button type="button" onclick={() => downloadProject()}>Save Project</button>
+      <button type="button" onclick={handleExportAudio}>Export Audio</button>
+    </div>
+    <div class="meta">
+      {#if app.videoName}
+        <span>{app.videoName}</span>
+      {/if}
+      {#if app.duration}
+        <label class="fps-control">
+          FPS
+          <input
+            type="number"
+            min="1"
+            max="240"
+            value={app.fps}
+            onchange={(event) => {
+              const value = Number(event.currentTarget.value);
+              if (value >= 1 && value <= 240) setFps(value);
+            }}
+          />
+        </label>
+      {/if}
+      {#if statusMessage}
+        <span class="status">{statusMessage}</span>
+      {/if}
+    </div>
+    <input bind:this={videoInput} type="file" accept="video/mp4,video/*" hidden onchange={handleVideoFile} />
+    <input bind:this={projectInput} type="file" accept="application/json,.json" hidden onchange={handleProjectFile} />
+  </header>
+
+  <section class="player-section">
+    {#if app.videoUrl}
+      <!-- svelte-ignore a11y_media_has_caption -->
+      <video
+        bind:this={videoEl}
+        src={app.videoUrl}
+        controls={false}
+        onplay={rescheduleAudio}
+        onpause={rescheduleAudio}
+        onseeked={rescheduleAudio}
+      ></video>
+    {:else}
+      <div class="placeholder">Open an MP4 video to begin annotating key presses</div>
+    {/if}
+  </section>
+
+  <section class="transport">
+    <button
+      type="button"
+      class="play-btn"
+      disabled={!app.videoUrl}
+      onclick={() => {
+        controller?.togglePlayPause();
+        rescheduleAudio();
+      }}
+    >
+      {app.isPlaying ? 'Pause' : 'Play'}
+    </button>
+    <span class="shortcut-hint">Ctrl+Space</span>
+
+    <label class="switch-select">
+      Switch
+      <select
+        value={app.activeSwitch}
+        onchange={(event) => {
+          setActiveSwitch(event.currentTarget.value as typeof app.activeSwitch);
+          rescheduleAudio();
+        }}
+      >
+        {#each SWITCH_OPTIONS as option}
+          <option value={option.id}>{option.label}</option>
+        {/each}
+      </select>
+    </label>
+  </section>
+
+  <Timeline
+    onSeek={(time) => {
+      controller?.seek(time);
+      rescheduleAudio();
+    }}
+    onReschedule={rescheduleAudio}
+  />
+</div>
+
+<style>
+  :global(body) {
+    margin: 0;
+    background: #111;
+    color: #eee;
+    font-family: Inter, system-ui, sans-serif;
+  }
+
+  .app {
+    min-height: 100vh;
+    display: flex;
+    flex-direction: column;
+    gap: 0.75rem;
+    padding: 1rem;
+    box-sizing: border-box;
+  }
+
+  .toolbar {
+    display: flex;
+    flex-wrap: wrap;
+    gap: 0.75rem;
+    align-items: center;
+    justify-content: space-between;
+  }
+
+  .file-actions {
+    display: flex;
+    gap: 0.5rem;
+    flex-wrap: wrap;
+  }
+
+  button,
+  select {
+    background: #2d3748;
+    color: #edf2f7;
+    border: 1px solid #4a5568;
+    border-radius: 6px;
+    padding: 0.45rem 0.75rem;
+    cursor: pointer;
+  }
+
+  button:disabled {
+    opacity: 0.5;
+    cursor: not-allowed;
+  }
+
+  .meta {
+    display: flex;
+    gap: 1rem;
+    font-size: 0.85rem;
+    color: #a0aec0;
+  }
+
+  .status {
+    color: #68d391;
+  }
+
+  .player-section {
+    background: #000;
+    border-radius: 8px;
+    overflow: hidden;
+    min-height: 320px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+  }
+
+  video {
+    width: 100%;
+    max-height: 60vh;
+    display: block;
+    background: #000;
+  }
+
+  .placeholder {
+    color: #718096;
+    padding: 3rem;
+    text-align: center;
+  }
+
+  .transport {
+    display: flex;
+    align-items: center;
+    gap: 0.75rem;
+  }
+
+  .play-btn {
+    min-width: 5rem;
+  }
+
+  .shortcut-hint {
+    font-size: 0.8rem;
+    color: #a0aec0;
+    padding: 0.2rem 0.5rem;
+    border: 1px dashed #4a5568;
+    border-radius: 4px;
+  }
+
+  .switch-select {
+    margin-left: auto;
+    display: flex;
+    align-items: center;
+    gap: 0.5rem;
+    font-size: 0.9rem;
+  }
+
+  .fps-control {
+    display: flex;
+    align-items: center;
+    gap: 0.35rem;
+  }
+
+  .fps-control input {
+    width: 4rem;
+    background: #2d3748;
+    color: #edf2f7;
+    border: 1px solid #4a5568;
+    border-radius: 4px;
+    padding: 0.2rem 0.35rem;
+  }
+</style>
@@ -0,0 +1,14 @@
+* {
+  box-sizing: border-box;
+}
+
+body {
+  margin: 0;
+}
+
+button:focus-visible,
+input:focus-visible,
+select:focus-visible {
+  outline: 2px solid #63b3ed;
+  outline-offset: 2px;
+}
@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" aria-hidden="true" role="img" class="iconify iconify--logos" width="26.6" height="32" preserveAspectRatio="xMidYMid meet" viewBox="0 0 256 308"><path fill="#FF3E00" d="M239.682 40.707C211.113-.182 154.69-12.301 113.895 13.69L42.247 59.356a82.198 82.198 0 0 0-37.135 55.056a86.566 86.566 0 0 0 8.536 55.576a82.425 82.425 0 0 0-12.296 30.719a87.596 87.596 0 0 0 14.964 66.244c28.574 40.893 84.997 53.007 125.787 27.016l71.648-45.664a82.182 82.182 0 0 0 37.135-55.057a86.601 86.601 0 0 0-8.53-55.577a82.409 82.409 0 0 0 12.29-30.718a87.573 87.573 0 0 0-14.963-66.244"></path><path fill="#FFF" d="M106.889 270.841c-23.102 6.007-47.497-3.036-61.103-22.648a52.685 52.685 0 0 1-9.003-39.85a49.978 49.978 0 0 1 1.713-6.693l1.35-4.115l3.671 2.697a92.447 92.447 0 0 0 28.036 14.007l2.663.808l-.245 2.659a16.067 16.067 0 0 0 2.89 10.656a17.143 17.143 0 0 0 18.397 6.828a15.786 15.786 0 0 0 4.403-1.935l71.67-45.672a14.922 14.922 0 0 0 6.734-9.977a15.923 15.923 0 0 0-2.713-12.011a17.156 17.156 0 0 0-18.404-6.832a15.78 15.78 0 0 0-4.396 1.933l-27.35 17.434a52.298 52.298 0 0 1-14.553 6.391c-23.101 6.007-47.497-3.036-61.101-22.649a52.681 52.681 0 0 1-9.004-39.849a49.428 49.428 0 0 1 22.34-33.114l71.664-45.677a52.218 52.218 0 0 1 14.563-6.398c23.101-6.007 47.497 3.036 61.101 22.648a52.685 52.685 0 0 1 9.004 39.85a50.559 50.559 0 0 1-1.713 6.692l-1.35 4.116l-3.67-2.693a92.373 92.373 0 0 0-28.037-14.013l-2.664-.809l.246-2.658a16.099 16.099 0 0 0-2.89-10.656a17.143 17.143 0 0 0-18.398-6.828a15.786 15.786 0 0 0-4.402 1.935l-71.67 45.674a14.898 14.898 0 0 0-6.73 9.975a15.9 15.9 0 0 0 2.709 12.012a17.156 17.156 0 0 0 18.404 6.832a15.841 15.841 0 0 0 4.402-1.935l27.345-17.427a52.147 52.147 0 0 1 14.552-6.397c23.101-6.006 47.497 3.037 61.102 22.65a52.681 52.681 0 0 1 9.003 39.848a49.453 49.453 0 0 1-22.34 33.12l-71.664 45.673a52.218 52.218 0 0 1-14.563 6.398"></path></svg>
@@ -0,0 +1,10 @@
+<script lang="ts">
+  let count: number = $state(0)
+  const increment = () => {
+    count += 1
+  }
+</script>
+
+<button type="button" class="counter" onclick={increment}>
+  Count is {count}
+</button>
@@ -0,0 +1,99 @@
+import type { Marker, SwitchType } from '../types';
+import { app } from '../store.svelte';
+
+const SAMPLE_PATHS: Record<SwitchType, string> = {
+  'cherry-mx-blue': '/assets/samples/cherry-mx-blue.wav',
+  'cherry-mx-red': '/assets/samples/cherry-mx-red.wav',
+  'cherry-mx-brown': '/assets/samples/cherry-mx-brown.wav',
+};
+
+export type AudioEngine = {
+  init: (video: HTMLVideoElement) => Promise<void>;
+  reschedule: (currentTime: number, markers: Marker[], isPlaying: boolean) => void;
+  destroy: () => void;
+};
+
+export function createAudioEngine(): AudioEngine {
+  let ctx: AudioContext | null = null;
+  let videoSource: MediaElementAudioSourceNode | null = null;
+  let videoGain: GainNode | null = null;
+  const buffers = new Map<SwitchType, AudioBuffer>();
+  const scheduledSources: AudioBufferSourceNode[] = [];
+
+  async function ensureContext() {
+    if (!ctx) ctx = new AudioContext();
+    if (ctx.state === 'suspended') await ctx.resume();
+    return ctx;
+  }
+
+  async function loadBuffer(switchType: SwitchType): Promise<AudioBuffer> {
+    const cached = buffers.get(switchType);
+    if (cached) return cached;
+    const audioCtx = await ensureContext();
+    const response = await fetch(SAMPLE_PATHS[switchType]);
+    const arrayBuffer = await response.arrayBuffer();
+    const audioBuffer = await audioCtx.decodeAudioData(arrayBuffer);
+    buffers.set(switchType, audioBuffer);
+    return audioBuffer;
+  }
+
+  function clearScheduled() {
+    for (const source of scheduledSources) {
+      try {
+        source.stop();
+      } catch {
+        // already stopped
+      }
+    }
+    scheduledSources.length = 0;
+  }
+
+  return {
+    async init(video: HTMLVideoElement) {
+      const audioCtx = await ensureContext();
+      if (!videoSource) {
+        videoSource = audioCtx.createMediaElementSource(video);
+        videoGain = audioCtx.createGain();
+        videoSource.connect(videoGain);
+        videoGain.connect(audioCtx.destination);
+      }
+      await Promise.all(
+        (Object.keys(SAMPLE_PATHS) as SwitchType[]).map((id) => loadBuffer(id)),
+      );
+    },
+
+    reschedule(time: number, markers: Marker[], playing: boolean) {
+      if (!ctx || !playing) {
+        clearScheduled();
+        return;
+      }
+
+      clearScheduled();
+      const audioCtx = ctx;
+      const startAt = audioCtx.currentTime + 0.02;
+      const buffer = buffers.get(app.activeSwitch);
+      if (!buffer) return;
+
+      for (const marker of markers) {
+        if (marker.time < time - 0.05) continue;
+        const delay = marker.time - time;
+        const source = audioCtx.createBufferSource();
+        source.buffer = buffer;
+        source.connect(audioCtx.destination);
+        source.start(startAt + Math.max(0, delay));
+        scheduledSources.push(source);
+      }
+    },
+
+    destroy() {
+      clearScheduled();
+      videoSource?.disconnect();
+      videoGain?.disconnect();
+      void ctx?.close();
+      ctx = null;
+      videoSource = null;
+      videoGain = null;
+      buffers.clear();
+    },
+  };
+}
@@ -0,0 +1,47 @@
+const MODIFIER_KEYS = new Set([
+  'Control',
+  'Shift',
+  'Alt',
+  'Meta',
+  'CapsLock',
+  'Tab',
+  'Escape',
+]);
+
+const IGNORED_KEYS = new Set([
+  ...MODIFIER_KEYS,
+  'ArrowUp',
+  'ArrowDown',
+  'ArrowLeft',
+  'ArrowRight',
+  'Backspace',
+  'Delete',
+  'Enter',
+  ' ',
+]);
+
+export function isEditableTarget(target: EventTarget | null): boolean {
+  if (!(target instanceof HTMLElement)) return false;
+  const tag = target.tagName;
+  return tag === 'INPUT' || tag === 'SELECT' || tag === 'TEXTAREA' || target.isContentEditable;
+}
+
+export function keyLabel(event: KeyboardEvent): string | null {
+  if (event.ctrlKey && event.code === 'Space') return null;
+  if (IGNORED_KEYS.has(event.key)) return null;
+  if (event.key.length === 1) return event.key;
+  if (event.key === ' ') return 'Space';
+  return event.key;
+}
+
+export function shouldOverrideSelected(event: KeyboardEvent, hasSelection: boolean): boolean {
+  if (!hasSelection) return false;
+  if (event.ctrlKey || event.metaKey || event.altKey) return false;
+  if (['ArrowLeft', 'ArrowRight', 'ArrowUp', 'ArrowDown'].includes(event.key)) return false;
+  return keyLabel(event) !== null;
+}
+
+export function shouldRecordMarker(event: KeyboardEvent): boolean {
+  if (event.ctrlKey || event.metaKey || event.altKey) return false;
+  return keyLabel(event) !== null;
+}
@@ -0,0 +1,56 @@
+import type { Project } from './types';
+import { app, setActiveSwitch, setMarkers, setSelectedIds } from './store.svelte';
+
+export function buildProject(): Project {
+  return {
+    version: 1,
+    switch: app.activeSwitch,
+    markers: app.markers.map((m) => ({ ...m })),
+  };
+}
+
+export function downloadProject(filename = 'project.json') {
+  const project = buildProject();
+  const blob = new Blob([JSON.stringify(project, null, 2)], { type: 'application/json' });
+  const url = URL.createObjectURL(blob);
+  const anchor = document.createElement('a');
+  anchor.href = url;
+  anchor.download = filename;
+  anchor.click();
+  URL.revokeObjectURL(url);
+}
+
+export function loadProject(data: Project) {
+  if (data.version !== 1) {
+    throw new Error(`Unsupported project version: ${data.version}`);
+  }
+  setMarkers(data.markers.map((m) => ({ ...m })));
+  setActiveSwitch(data.switch);
+  setSelectedIds(new Set());
+}
+
+export async function exportAudio(duration: number) {
+  const project = buildProject();
+  const response = await fetch('/api/export/audio', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({
+      duration,
+      switch: project.switch,
+      markers: project.markers,
+    }),
+  });
+
+  if (!response.ok) {
+    const detail = await response.text();
+    throw new Error(detail || 'Audio export failed');
+  }
+
+  const blob = await response.blob();
+  const url = URL.createObjectURL(blob);
+  const anchor = document.createElement('a');
+  anchor.href = url;
+  anchor.download = 'keyboard_track.wav';
+  anchor.click();
+  URL.revokeObjectURL(url);
+}
@@ -0,0 +1,132 @@
+import type { Marker, SwitchType } from './types';
+import { ZOOM_DEFAULT } from './types';
+
+export const app = $state({
+  markers: [] as Marker[],
+  selectedIds: new Set<string>(),
+  isPlaying: false,
+  currentTime: 0,
+  duration: 0,
+  fps: 30,
+  pixelsPerSecond: ZOOM_DEFAULT,
+  scrollLeft: 0,
+  activeSwitch: 'cherry-mx-blue' as SwitchType,
+  videoUrl: null as string | null,
+  videoName: null as string | null,
+  timelineWidth: 800,
+});
+
+let markerCounter = 0;
+
+export function createMarkerId(): string {
+  markerCounter += 1;
+  return `m${markerCounter}`;
+}
+
+export function setMarkers(value: Marker[]) {
+  app.markers = value;
+  const maxId = value.reduce((max, m) => {
+    const num = parseInt(m.id.replace(/\D/g, ''), 10);
+    return Number.isFinite(num) ? Math.max(max, num) : max;
+  }, 0);
+  markerCounter = maxId;
+}
+
+export function setSelectedIds(ids: Set<string>) {
+  app.selectedIds = ids;
+}
+
+export function setCurrentTime(value: number) {
+  app.currentTime = value;
+}
+
+export function setDuration(value: number) {
+  app.duration = value;
+}
+
+export function setIsPlaying(value: boolean) {
+  app.isPlaying = value;
+}
+
+export function setFps(value: number) {
+  app.fps = value;
+}
+
+export function setPixelsPerSecond(value: number) {
+  app.pixelsPerSecond = value;
+}
+
+export function setScrollLeft(value: number) {
+  app.scrollLeft = value;
+}
+
+export function setActiveSwitch(value: SwitchType) {
+  app.activeSwitch = value;
+}
+
+export function setTimelineWidth(value: number) {
+  app.timelineWidth = value;
+}
+
+export function addMarker(time: number, key: string): Marker {
+  const marker: Marker = { id: createMarkerId(), time, key };
+  app.markers = [...app.markers, marker].sort((a, b) => a.time - b.time);
+  return marker;
+}
+
+export function updateMarker(id: string, patch: Partial<Pick<Marker, 'time' | 'key'>>) {
+  app.markers = app.markers
+    .map((m) => (m.id === id ? { ...m, ...patch } : m))
+    .sort((a, b) => a.time - b.time);
+}
+
+export function setMarkerTimes(updates: Map<string, number>) {
+  app.markers = app.markers
+    .map((m) => {
+      const time = updates.get(m.id);
+      return time === undefined ? m : { ...m, time };
+    })
+    .sort((a, b) => a.time - b.time);
+}
+
+export function deleteMarkers(ids: Set<string>) {
+  app.markers = app.markers.filter((m) => !ids.has(m.id));
+  const next = new Set(app.selectedIds);
+  for (const id of ids) next.delete(id);
+  app.selectedIds = next;
+}
+
+export function selectAll() {
+  app.selectedIds = new Set(app.markers.map((m) => m.id));
+}
+
+export function toggleSelection(id: string, additive: boolean) {
+  const next = additive ? new Set(app.selectedIds) : new Set<string>();
+  if (next.has(id)) next.delete(id);
+  else next.add(id);
+  app.selectedIds = next;
+}
+
+export function setVideoUrl(url: string | null, name: string | null = null) {
+  if (app.videoUrl) URL.revokeObjectURL(app.videoUrl);
+  app.videoUrl = url;
+  app.videoName = name;
+}
+
+export function snapToFrame(time: number): number {
+  const frameDuration = 1 / app.fps;
+  return Math.round(time / frameDuration) * frameDuration;
+}
+
+export function nudgeSelected(deltaFrames: number) {
+  if (app.selectedIds.size === 0) return;
+  const frameDuration = 1 / app.fps;
+  const delta = deltaFrames * frameDuration;
+  app.markers = app.markers
+    .map((m) => {
+      if (!app.selectedIds.has(m.id)) return m;
+      const next = Math.max(0, Math.min(app.duration || Infinity, m.time + delta));
+      return { ...m, time: snapToFrame(next) };
+    })
+    .sort((a, b) => a.time - b.time);
+}
@@ -0,0 +1,353 @@
+<script lang="ts">
+  import {
+    app,
+    setMarkerTimes,
+    setPixelsPerSecond,
+    setScrollLeft,
+    setSelectedIds,
+    setTimelineWidth,
+    snapToFrame,
+    toggleSelection,
+  } from '../store.svelte';
+  import { ZOOM_MAX, ZOOM_MIN } from '../types';
+  import {
+    centerScrollOnPlayhead,
+    formatTime,
+    pxToTime,
+    tickInterval,
+    timeToPx,
+  } from './math';
+
+  interface Props {
+    onSeek?: (time: number) => void;
+    onReschedule?: () => void;
+  }
+
+  let { onSeek, onReschedule }: Props = $props();
+
+  let viewportEl: HTMLDivElement | undefined = $state();
+  let dragMode = $state<'none' | 'marker' | 'marquee' | 'move'>('none');
+  let dragMarkerId = $state<string | null>(null);
+  let dragStartX = 0;
+  let marqueeStart = 0;
+  let marqueeEnd = 0;
+  let moveStartTimes = new Map<string, number>();
+
+  function updateScrollCenter() {
+    setScrollLeft(
+      centerScrollOnPlayhead(app.currentTime, app.pixelsPerSecond, app.timelineWidth),
+    );
+  }
+
+  $effect(() => {
+    void app.currentTime;
+    void app.pixelsPerSecond;
+    if (app.duration > 0 && viewportEl) updateScrollCenter();
+  });
+
+  $effect(() => {
+    if (!viewportEl) return;
+    const observer = new ResizeObserver(() => {
+      setTimelineWidth(viewportEl!.clientWidth);
+    });
+    observer.observe(viewportEl);
+    setTimelineWidth(viewportEl.clientWidth);
+    return () => observer.disconnect();
+  });
+
+  function clampZoom(value: number) {
+    return Math.max(ZOOM_MIN, Math.min(ZOOM_MAX, value));
+  }
+
+  function handleWheel(event: WheelEvent) {
+    if (!event.altKey) return;
+    event.preventDefault();
+    const factor = event.deltaY < 0 ? 1.15 : 1 / 1.15;
+    setPixelsPerSecond(clampZoom(app.pixelsPerSecond * factor));
+    updateScrollCenter();
+  }
+
+  function localX(event: PointerEvent): number {
+    if (!viewportEl) return 0;
+    const rect = viewportEl.getBoundingClientRect();
+    return event.clientX - rect.left + app.scrollLeft;
+  }
+
+  function handlePointerDown(event: PointerEvent) {
+    if (!viewportEl) return;
+    const x = localX(event);
+    const time = pxToTime(x, app.pixelsPerSecond);
+    const target = event.target as HTMLElement;
+    const markerEl = target.closest('[data-marker-id]') as HTMLElement | null;
+
+    if (markerEl?.dataset.markerId) {
+      const id = markerEl.dataset.markerId;
+      toggleSelection(id, event.shiftKey);
+      dragMode = app.selectedIds.has(id) ? 'move' : 'marker';
+      dragMarkerId = id;
+      dragStartX = x;
+      moveStartTimes = new Map(
+        app.markers.filter((m) => app.selectedIds.has(m.id)).map((m) => [m.id, m.time]),
+      );
+      viewportEl.setPointerCapture(event.pointerId);
+      return;
+    }
+
+    if (!event.shiftKey) setSelectedIds(new Set());
+    dragMode = 'marquee';
+    marqueeStart = time;
+    marqueeEnd = time;
+    viewportEl.setPointerCapture(event.pointerId);
+  }
+
+  function handlePointerMove(event: PointerEvent) {
+    if (dragMode === 'none' || !viewportEl) return;
+    const x = localX(event);
+
+    if (dragMode === 'marquee') {
+      marqueeEnd = pxToTime(x, app.pixelsPerSecond);
+      return;
+    }
+
+    if (dragMode === 'move' && moveStartTimes.size > 0) {
+      const deltaTime = pxToTime(x - dragStartX, app.pixelsPerSecond);
+      const updates = new Map<string, number>();
+      for (const [id, start] of moveStartTimes) {
+        const next = Math.max(0, Math.min(app.duration || Infinity, start + deltaTime));
+        updates.set(id, snapToFrame(next));
+      }
+      setMarkerTimes(updates);
+      return;
+    }
+
+    if (dragMode === 'marker' && dragMarkerId) {
+      const time = snapToFrame(
+        Math.max(0, Math.min(app.duration || Infinity, pxToTime(x, app.pixelsPerSecond))),
+      );
+      setMarkerTimes(new Map([[dragMarkerId, time]]));
+    }
+  }
+
+  function handlePointerUp(event: PointerEvent) {
+    if (dragMode === 'marquee') {
+      const minT = Math.min(marqueeStart, marqueeEnd);
+      const maxT = Math.max(marqueeStart, marqueeEnd);
+      const hits = app.markers.filter((m) => m.time >= minT && m.time <= maxT).map((m) => m.id);
+      setSelectedIds(new Set(hits));
+    }
+
+    if (dragMode === 'move' || dragMode === 'marker') {
+      onReschedule?.();
+    }
+
+    dragMode = 'none';
+    dragMarkerId = null;
+    moveStartTimes.clear();
+    viewportEl?.releasePointerCapture(event.pointerId);
+  }
+
+  function handleRulerClick(event: MouseEvent) {
+    if (dragMode !== 'none') return;
+    const x = localX(event as unknown as PointerEvent);
+    const time = snapToFrame(
+      Math.max(0, Math.min(app.duration || Infinity, pxToTime(x, app.pixelsPerSecond))),
+    );
+    onSeek?.(time);
+  }
+
+  function handleZoomInput(event: Event) {
+    const value = Number((event.currentTarget as HTMLInputElement).value);
+    setPixelsPerSecond(value);
+    updateScrollCenter();
+  }
+
+  const contentWidth = $derived(
+    Math.max(app.timelineWidth, timeToPx(app.duration || 1, app.pixelsPerSecond) + 40),
+  );
+  const ticks = $derived.by(() => {
+    const interval = tickInterval(app.pixelsPerSecond);
+    const count = Math.ceil((app.duration || 1) / interval);
+    return Array.from({ length: count + 1 }, (_, i) => i * interval);
+  });
+  const playheadX = $derived(timeToPx(app.currentTime, app.pixelsPerSecond));
+  const marqueeVisible = $derived(dragMode === 'marquee');
+  const marqueeLeft = $derived(timeToPx(Math.min(marqueeStart, marqueeEnd), app.pixelsPerSecond));
+  const marqueeWidth = $derived(
+    Math.abs(
+      timeToPx(marqueeEnd, app.pixelsPerSecond) - timeToPx(marqueeStart, app.pixelsPerSecond),
+    ),
+  );
+</script>
+
+<div class="timeline-panel">
+  <div class="zoom-row">
+    <label for="zoom-slider">Zoom</label>
+    <input
+      id="zoom-slider"
+      type="range"
+      min={ZOOM_MIN}
+      max={ZOOM_MAX}
+      value={app.pixelsPerSecond}
+      oninput={handleZoomInput}
+    />
+    <span class="hint">Alt + scroll to zoom</span>
+  </div>
+
+  <div class="timeline-viewport" bind:this={viewportEl} onwheel={handleWheel}>
+    <div
+      class="timeline-content"
+      style="width: {contentWidth}px; transform: translateX({-app.scrollLeft}px);"
+    >
+      <!-- svelte-ignore a11y_click_events_have_key_events -->
+      <!-- svelte-ignore a11y_no_static_element_interactions -->
+      <div
+        class="ruler"
+        onclick={handleRulerClick}
+        onpointerdown={handlePointerDown}
+        onpointermove={handlePointerMove}
+        onpointerup={handlePointerUp}
+      >
+        {#each ticks as tick}
+          <div class="tick" style="left: {timeToPx(tick, app.pixelsPerSecond)}px">
+            <span>{formatTime(tick)}</span>
+          </div>
+        {/each}
+      </div>
+
+      <!-- svelte-ignore a11y_no_static_element_interactions -->
+      <div
+        class="track"
+        onpointerdown={handlePointerDown}
+        onpointermove={handlePointerMove}
+        onpointerup={handlePointerUp}
+      >
+        {#each app.markers as marker (marker.id)}
+          <button
+            type="button"
+            class="marker"
+            class:selected={app.selectedIds.has(marker.id)}
+            data-marker-id={marker.id}
+            style="left: {timeToPx(marker.time, app.pixelsPerSecond)}px"
+            title="{marker.key} @ {formatTime(marker.time)}"
+          >
+            {marker.key}
+          </button>
+        {/each}
+
+        {#if marqueeVisible}
+          <div class="marquee" style="left: {marqueeLeft}px; width: {marqueeWidth}px"></div>
+        {/if}
+
+        <div class="playhead" style="left: {playheadX}px"></div>
+      </div>
+    </div>
+  </div>
+</div>
+
+<style>
+  .timeline-panel {
+    display: flex;
+    flex-direction: column;
+    gap: 0.5rem;
+    border-top: 1px solid #333;
+    padding-top: 0.75rem;
+  }
+
+  .zoom-row {
+    display: flex;
+    align-items: center;
+    gap: 0.75rem;
+    font-size: 0.85rem;
+    color: #aaa;
+  }
+
+  .zoom-row input[type='range'] {
+    flex: 1;
+    max-width: 240px;
+  }
+
+  .hint {
+    margin-left: auto;
+  }
+
+  .timeline-viewport {
+    position: relative;
+    overflow: hidden;
+    height: 120px;
+    background: #1a1a1a;
+    border: 1px solid #333;
+    border-radius: 6px;
+    user-select: none;
+    touch-action: none;
+  }
+
+  .timeline-content {
+    position: relative;
+    height: 100%;
+    will-change: transform;
+  }
+
+  .ruler {
+    position: relative;
+    height: 28px;
+    border-bottom: 1px solid #333;
+    background: #222;
+    cursor: pointer;
+  }
+
+  .tick {
+    position: absolute;
+    top: 0;
+    height: 100%;
+    border-left: 1px solid #444;
+    padding-left: 4px;
+    font-size: 0.65rem;
+    color: #888;
+    pointer-events: none;
+  }
+
+  .track {
+    position: relative;
+    height: calc(100% - 28px);
+    cursor: crosshair;
+  }
+
+  .marker {
+    position: absolute;
+    top: 18px;
+    transform: translateX(-50%);
+    padding: 0.2rem 0.45rem;
+    border: 1px solid #555;
+    border-radius: 4px;
+    background: #2d3748;
+    color: #e2e8f0;
+    font-size: 0.75rem;
+    cursor: grab;
+    white-space: nowrap;
+  }
+
+  .marker.selected {
+    background: #3182ce;
+    border-color: #63b3ed;
+    box-shadow: 0 0 0 1px #63b3ed;
+  }
+
+  .marquee {
+    position: absolute;
+    top: 8px;
+    height: 72px;
+    background: rgba(99, 179, 237, 0.2);
+    border: 1px solid #63b3ed;
+    pointer-events: none;
+  }
+
+  .playhead {
+    position: absolute;
+    top: 0;
+    bottom: 0;
+    width: 2px;
+    background: #f56565;
+    pointer-events: none;
+    z-index: 2;
+  }
+</style>
@@ -0,0 +1,30 @@
+export function timeToPx(time: number, pixelsPerSecond: number): number {
+  return time * pixelsPerSecond;
+}
+
+export function pxToTime(px: number, pixelsPerSecond: number): number {
+  return px / pixelsPerSecond;
+}
+
+export function centerScrollOnPlayhead(
+  playheadTime: number,
+  pixelsPerSecond: number,
+  viewportWidth: number,
+): number {
+  const playheadPx = timeToPx(playheadTime, pixelsPerSecond);
+  return Math.max(0, playheadPx - viewportWidth / 2);
+}
+
+export function formatTime(seconds: number): string {
+  const mins = Math.floor(seconds / 60);
+  const secs = seconds % 60;
+  return `${mins}:${secs.toFixed(2).padStart(5, '0')}`;
+}
+
+export function tickInterval(pixelsPerSecond: number): number {
+  if (pixelsPerSecond >= 200) return 0.1;
+  if (pixelsPerSecond >= 100) return 0.5;
+  if (pixelsPerSecond >= 50) return 1;
+  if (pixelsPerSecond >= 25) return 2;
+  return 5;
+}
@@ -0,0 +1,23 @@
+export type SwitchType = 'cherry-mx-blue' | 'cherry-mx-red' | 'cherry-mx-brown';
+
+export interface Marker {
+  id: string;
+  time: number;
+  key: string;
+}
+
+export interface Project {
+  version: number;
+  switch: SwitchType;
+  markers: Marker[];
+}
+
+export const SWITCH_OPTIONS: { id: SwitchType; label: string }[] = [
+  { id: 'cherry-mx-blue', label: 'Cherry MX Blue (clicky)' },
+  { id: 'cherry-mx-red', label: 'Cherry MX Red (linear)' },
+  { id: 'cherry-mx-brown', label: 'Cherry MX Brown (tactile)' },
+];
+
+export const ZOOM_MIN = 20;
+export const ZOOM_MAX = 400;
+export const ZOOM_DEFAULT = 80;
@@ -0,0 +1,103 @@
+import { app, setCurrentTime, setDuration, setFps, setIsPlaying, snapToFrame } from '../store.svelte';
+
+export type VideoController = {
+  element: HTMLVideoElement;
+  destroy: () => void;
+  togglePlayPause: () => void;
+  stepFrame: (delta: number) => void;
+  seek: (time: number) => void;
+};
+
+export function attachVideoPlayer(video: HTMLVideoElement): VideoController {
+  let rafId = 0;
+  let lastFrameTime: number | null = null;
+  const frameDeltas: number[] = [];
+
+  const onLoadedMetadata = () => {
+    setDuration(video.duration);
+    setCurrentTime(video.currentTime);
+  };
+
+  const onPlay = () => setIsPlaying(true);
+  const onPause = () => setIsPlaying(false);
+  const onSeeked = () => setCurrentTime(video.currentTime);
+  const onEnded = () => setIsPlaying(false);
+
+  const detectFps = (mediaTime: number) => {
+    if (lastFrameTime !== null) {
+      const delta = mediaTime - lastFrameTime;
+      if (delta > 0.001 && delta < 0.2) {
+        frameDeltas.push(delta);
+        if (frameDeltas.length > 30) frameDeltas.shift();
+        if (frameDeltas.length >= 10) {
+          const avg = frameDeltas.reduce((a, b) => a + b, 0) / frameDeltas.length;
+          const detected = Math.round(1 / avg);
+          if (detected >= 10 && detected <= 120) setFps(detected);
+        }
+      }
+    }
+    lastFrameTime = mediaTime;
+  };
+
+  const frameLoop = (_now: number, metadata: VideoFrameCallbackMetadata) => {
+    setCurrentTime(metadata.mediaTime);
+    detectFps(metadata.mediaTime);
+    if (!video.paused && !video.ended) {
+      video.requestVideoFrameCallback(frameLoop);
+    }
+  };
+
+  const timeLoop = () => {
+    if (!video.paused) {
+      setCurrentTime(video.currentTime);
+      rafId = requestAnimationFrame(timeLoop);
+    }
+  };
+
+  const onPlayStart = () => {
+    if ('requestVideoFrameCallback' in video) {
+      video.requestVideoFrameCallback(frameLoop);
+    } else {
+      rafId = requestAnimationFrame(timeLoop);
+    }
+  };
+
+  video.addEventListener('loadedmetadata', onLoadedMetadata);
+  video.addEventListener('play', onPlay);
+  video.addEventListener('play', onPlayStart);
+  video.addEventListener('pause', onPause);
+  video.addEventListener('seeked', onSeeked);
+  video.addEventListener('ended', onEnded);
+
+  if (video.readyState >= 1) onLoadedMetadata();
+
+  return {
+    element: video,
+    destroy() {
+      cancelAnimationFrame(rafId);
+      video.removeEventListener('loadedmetadata', onLoadedMetadata);
+      video.removeEventListener('play', onPlay);
+      video.removeEventListener('play', onPlayStart);
+      video.removeEventListener('pause', onPause);
+      video.removeEventListener('seeked', onSeeked);
+      video.removeEventListener('ended', onEnded);
+    },
+    togglePlayPause() {
+      if (video.paused || video.ended) void video.play();
+      else video.pause();
+    },
+    stepFrame(delta: number) {
+      video.pause();
+      const next = snapToFrame(
+        Math.max(0, Math.min(video.duration || 0, video.currentTime + delta / app.fps)),
+      );
+      video.currentTime = next;
+      setCurrentTime(next);
+    },
+    seek(time: number) {
+      const clamped = Math.max(0, Math.min(video.duration || 0, time));
+      video.currentTime = clamped;
+      setCurrentTime(clamped);
+    },
+  };
+}
@@ -0,0 +1,9 @@
+import { mount } from 'svelte'
+import './app.css'
+import App from './App.svelte'
+
+const app = mount(App, {
+  target: document.getElementById('app')!,
+})
+
+export default app
@@ -0,0 +1,2 @@
+/** @type {import("@sveltejs/vite-plugin-svelte").SvelteConfig} */
+export default {}
@@ -0,0 +1,20 @@
+{
+  "extends": "@tsconfig/svelte/tsconfig.json",
+  "compilerOptions": {
+    "tsBuildInfoFile": "./node_modules/.tmp/tsconfig.app.tsbuildinfo",
+    "target": "es2023",
+    "module": "esnext",
+    "types": ["svelte", "vite/client"],
+    "noEmit": true,
+    /**
+     * Typecheck JS in `.svelte` and `.js` files by default.
+     * Disable checkJs if you'd like to use dynamic types in JS.
+     * Note that setting allowJs false does not prevent the use
+     * of JS in `.svelte` files.
+     */
+    "allowJs": true,
+    "checkJs": true,
+    "moduleDetection": "force"
+  },
+  "include": ["src/**/*.ts", "src/**/*.js", "src/**/*.svelte"]
+}
@@ -0,0 +1,7 @@
+{
+  "files": [],
+  "references": [
+    { "path": "./tsconfig.app.json" },
+    { "path": "./tsconfig.node.json" }
+  ]
+}
@@ -0,0 +1,24 @@
+{
+  "compilerOptions": {
+    "tsBuildInfoFile": "./node_modules/.tmp/tsconfig.node.tsbuildinfo",
+    "target": "es2023",
+    "lib": ["ES2023"],
+    "module": "esnext",
+    "types": ["node"],
+    "skipLibCheck": true,
+
+    /* Bundler mode */
+    "moduleResolution": "bundler",
+    "allowImportingTsExtensions": true,
+    "verbatimModuleSyntax": true,
+    "moduleDetection": "force",
+    "noEmit": true,
+
+    /* Linting */
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "erasableSyntaxOnly": true,
+    "noFallthroughCasesInSwitch": true
+  },
+  "include": ["vite.config.ts"]
+}
@@ -0,0 +1,12 @@
+import { defineConfig } from 'vite'
+import { svelte } from '@sveltejs/vite-plugin-svelte'
+
+export default defineConfig({
+  plugins: [svelte()],
+  server: {
+    proxy: {
+      '/api': 'http://127.0.0.1:8000',
+      '/assets': 'http://127.0.0.1:8000',
+    },
+  },
+})
@@ -0,0 +1,16 @@
+[project]
+name = "sfxkeeb"
+version = "0.1.0"
+description = "Video keyboard SFX annotator with timeline editing and audio export"
+readme = "README.md"
+requires-python = ">=3.9"
+dependencies = [
+    "fastapi>=0.128.8",
+    "pydantic>=2.13.4",
+    "pydub>=0.25.1",
+    "python-multipart>=0.0.20",
+    "uvicorn[standard]>=0.39.0",
+]
+
+[project.scripts]
+sfxkeeb = "backend.main:run"
@@ -0,0 +1,83 @@
+"""Generate synthetic mechanical keyboard switch samples."""
+
+import math
+import struct
+import wave
+from pathlib import Path
+
+SAMPLE_RATE = 48000
+OUT_DIR = Path(__file__).resolve().parent.parent / "assets" / "samples"
+
+
+def write_wav(path: Path, samples: list[float]) -> None:
+    pcm = b"".join(
+        struct.pack("<h", max(-32768, min(32767, int(s * 32767)))) for s in samples
+    )
+    with wave.open(str(path), "w") as wf:
+        wf.setnchannels(1)
+        wf.setsampwidth(2)
+        wf.setframerate(SAMPLE_RATE)
+        wf.writeframes(pcm)
+
+
+def envelope(length: int, attack: float, decay: float) -> list[float]:
+    env = []
+    attack_samples = int(attack * SAMPLE_RATE)
+    decay_samples = int(decay * SAMPLE_RATE)
+    for i in range(length):
+        if i < attack_samples:
+            env.append(i / max(attack_samples, 1))
+        elif i < attack_samples + decay_samples:
+            t = (i - attack_samples) / max(decay_samples, 1)
+            env.append(1.0 - t)
+        else:
+            env.append(0.0)
+    return env
+
+
+def generate_click(
+    freq: float,
+    duration: float,
+    attack: float,
+    decay: float,
+    noise_mix: float = 0.0,
+    click_burst: bool = False,
+) -> list[float]:
+    length = int(duration * SAMPLE_RATE)
+    env = envelope(length, attack, decay)
+    out = []
+    for i in range(length):
+        t = i / SAMPLE_RATE
+        tone = math.sin(2 * math.pi * freq * t) * (0.7 if not click_burst else 0.4)
+        if click_burst and t < 0.008:
+            tone += math.sin(2 * math.pi * (freq * 2.8) * t) * 0.5
+        noise = 0.0
+        if noise_mix > 0:
+            noise = (((i * 1103515245 + 12345) & 0x7FFFFFFF) / 0x7FFFFFFF - 0.5) * noise_mix
+        out.append((tone + noise) * env[i])
+    peak = max(abs(s) for s in out) or 1.0
+    return [s / peak * 0.85 for s in out]
+
+
+def main() -> None:
+    OUT_DIR.mkdir(parents=True, exist_ok=True)
+
+    profiles = {
+        "cherry-mx-blue.wav": generate_click(
+            2800, 0.09, 0.001, 0.085, noise_mix=0.15, click_burst=True
+        ),
+        "cherry-mx-red.wav": generate_click(
+            1200, 0.05, 0.002, 0.045, noise_mix=0.08
+        ),
+        "cherry-mx-brown.wav": generate_click(
+            1800, 0.07, 0.002, 0.065, noise_mix=0.12, click_burst=True
+        ),
+    }
+
+    for name, samples in profiles.items():
+        write_wav(OUT_DIR / name, samples)
+        print(f"Wrote {OUT_DIR / name}")
+
+
+if __name__ == "__main__":
+    main()
				`@@ -0,0 +1 @@`
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