diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 429f14d..d22ca03 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,6 +22,7 @@ jobs:
           cache: npm
       # --ignore-scripts: skip transitive `sharp` native build (unused; browser only)
       - run: npm ci --ignore-scripts
+      - run: npm run test:unit
       - run: npm run build
 
   # Vendored ACE-Step runtime (packages/acestep): typecheck + weight-free
diff --git a/package.json b/package.json
index 36ad839..e287e47 100644
--- a/package.json
+++ b/package.json
@@ -44,6 +44,7 @@
     "dicose:test": "npm run test --workspace dicose-wgsl",
     "build": "npm run acestep:build && npm run dicose:build && tsc --noEmit && vite build && node scripts/postbuild-strip-wasm.mjs",
     "preview": "vite preview",
+    "test:unit": "node --test test/*.test.mjs",
     "typecheck": "tsc --noEmit",
     "gpu:verify": "node scripts/gpu-verify.mjs",
     "gpu:bench": "node scripts/gpu-bench.mjs",
@@ -56,8 +57,8 @@
     "wasm:build": "cd rust/wasm-kernels && RUSTFLAGS='-C target-feature=+simd128' cargo build --release --target wasm32-unknown-unknown && cp target/wasm32-unknown-unknown/release/wasm_kernels.wasm ../../src/gpu/wasm-kernels.wasm",
     "wasm:verify": "node scripts/wasm-verify.mjs",
     "backend:parity": "node scripts/backend-parity.mjs",
-    "format": "prettier --write \"src/**/*.{ts,js}\" \"scripts/**/*.mjs\" \"*.ts\"",
-    "format:check": "prettier --check \"src/**/*.{ts,js}\" \"scripts/**/*.mjs\" \"*.ts\"",
+    "format": "prettier --write \"src/**/*.{ts,js}\" \"scripts/**/*.mjs\" \"test/**/*.mjs\" \"*.ts\"",
+    "format:check": "prettier --check \"src/**/*.{ts,js}\" \"scripts/**/*.mjs\" \"test/**/*.mjs\" \"*.ts\"",
     "ci:smoke": "node scripts/interface-conformance.mjs && node scripts/ci-smoke-parakeet.mjs && node scripts/ci-smoke-eou.mjs && node scripts/ci-smoke-kokoro.mjs",
     "sdk:build": "node scripts/build-sdk.mjs",
     "sdk:pack": "node scripts/build-sdk.mjs && cd dist-sdk && npm pack --pack-destination ..",
diff --git a/src/core/loadProgress.d.ts b/src/core/loadProgress.d.ts
new file mode 100644
index 0000000..af24440
--- /dev/null
+++ b/src/core/loadProgress.d.ts
@@ -0,0 +1,4 @@
+import type { LoadProgress } from "./types.js";
+
+/** Format one model-load progress update for the browser UI. */
+export declare function formatLoadProgress(progress: LoadProgress): string;
diff --git a/src/core/loadProgress.js b/src/core/loadProgress.js
new file mode 100644
index 0000000..3cfd19b
--- /dev/null
+++ b/src/core/loadProgress.js
@@ -0,0 +1,21 @@
+/** Format one model-load progress update for the browser UI. */
+export function formatLoadProgress(progress) {
+  const fraction = Number.isFinite(progress.fraction) ? Math.min(1, Math.max(0, progress.fraction)) : 0;
+  const percentage = Math.round(fraction * 100);
+  const file = progress.file || "model";
+
+  if (progress.phase !== "download") return `Loading ${file} — ${percentage}%`;
+
+  const amount = formatDownloadAmount(progress.loaded, progress.total);
+  return `Downloading ${file} — ${percentage}%${amount ? ` (${amount})` : ""}`;
+}
+
+function formatDownloadAmount(loaded, total) {
+  if (!Number.isFinite(loaded) || !Number.isFinite(total) || total <= 0) return "";
+
+  const units = ["B", "KB", "MB", "GB"];
+  const unitIndex = Math.min(units.length - 1, Math.max(0, Math.floor(Math.log10(total) / 3)));
+  const divisor = 1000 ** unitIndex;
+  const decimals = total / divisor < 10 && unitIndex > 0 ? 1 : 0;
+  return `${(Math.max(0, loaded) / divisor).toFixed(decimals)} / ${(total / divisor).toFixed(decimals)} ${units[unitIndex]}`;
+}
diff --git a/src/core/modelCache.ts b/src/core/modelCache.ts
index ee13d28..4d470d0 100644
--- a/src/core/modelCache.ts
+++ b/src/core/modelCache.ts
@@ -53,7 +53,7 @@ export async function fetchCached(url: string, onProgress?: ProgressCb, label =
     if (done) break;
     chunks.push(value);
     loaded += value.byteLength;
-    onProgress?.({ file: label, loaded, total, fraction: total ? loaded / total : 0 });
+    onProgress?.({ file: label, phase: "download", loaded, total, fraction: total ? loaded / total : 0 });
   }
 
   const bytes = concat(chunks, loaded);
@@ -83,6 +83,7 @@ export async function fetchAll(files: { repo: string; path: string; revision?: s
       (p) => {
         onProgress?.({
           file: f.path,
+          phase: p.phase,
           loaded: doneBytes + p.loaded,
           total: 0,
           fraction: (i + p.fraction) / files.length,
diff --git a/src/core/types.ts b/src/core/types.ts
index 3a96b76..76fc1f0 100644
--- a/src/core/types.ts
+++ b/src/core/types.ts
@@ -10,6 +10,8 @@ export interface AudioData {
 export interface LoadProgress {
   /** File or component currently loading. */
   file: string;
+  /** Work currently represented by this update. Defaults to local loading. */
+  phase?: "download" | "load";
   /** Bytes fetched so far / total (total may be 0 if unknown). */
   loaded: number;
   total: number;
diff --git a/src/live.ts b/src/live.ts
index 1a9599b..48e887e 100644
--- a/src/live.ts
+++ b/src/live.ts
@@ -9,6 +9,7 @@ initSiteTheme();
 // last finalize boundary.
 
 import { ENGINES } from "./engines/registry.js";
+import { formatLoadProgress } from "./core/loadProgress.js";
 import { MicCapture } from "./core/mic.js";
 import type { Engine } from "./core/types.js";
 
@@ -114,7 +115,7 @@ async function start() {
       $("status").textContent = `loading ${c.label}…`;
       const e = await c.make();
       await e.load((p) => {
-        $("status").textContent = `loading ${p.file ?? ""} ${Math.round((p.fraction || 0) * 100)}%`;
+        $("status").textContent = formatLoadProgress(p);
       });
       engine = e as StreamingEngine;
       engineId = id;
diff --git a/src/pages/playground.ts b/src/pages/playground.ts
index f4e1fa6..c748f48 100644
--- a/src/pages/playground.ts
+++ b/src/pages/playground.ts
@@ -8,6 +8,7 @@ import { initSiteTheme } from "../theme/theme.js";
 
 import { decodeToMono16k, pcmToWav } from "../core/audio.js";
 import { segmentsToSrt, segmentsToVtt } from "../core/captions.js";
+import { formatLoadProgress } from "../core/loadProgress.js";
 import { webgpuAvailable } from "../core/webgpu.js";
 import { ENGINES, type EngineCategory, type EngineEntry } from "../engines/registry.js";
 import { MicCapture } from "../core/mic.js";
@@ -147,7 +148,7 @@ export function initPlayground(opts: PlaygroundOptions) {
       status.textContent = `Loading ${entry.label}…`;
       await eng.load((p: LoadProgress) => {
         progress.value = p.fraction || 0;
-        status.textContent = `Loading ${p.file} — ${Math.round((p.fraction || 0) * 100)}%`;
+        status.textContent = formatLoadProgress(p);
       });
       status.textContent = `Ready: ${entry.label}`;
       runBtn.disabled = false;
diff --git a/test/load-progress.test.mjs b/test/load-progress.test.mjs
new file mode 100644
index 0000000..604bbf5
--- /dev/null
+++ b/test/load-progress.test.mjs
@@ -0,0 +1,29 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+import { formatLoadProgress } from "../src/core/loadProgress.js";
+
+test("labels streamed model bytes as a download with byte progress", () => {
+  assert.equal(
+    formatLoadProgress({
+      file: "parakeet/encoder-int8.bin",
+      phase: "download",
+      loaded: 195_743_171,
+      total: 611_697_408,
+      fraction: 0.32,
+    }),
+    "Downloading parakeet/encoder-int8.bin — 32% (196 / 612 MB)",
+  );
+});
+
+test("keeps local initialization labeled as loading", () => {
+  assert.equal(formatLoadProgress({ file: "WebGPU pipelines", phase: "load", loaded: 1, total: 4, fraction: 0.25 }), "Loading WebGPU pipelines — 25%");
+});
+
+test("supports existing progress producers without a phase", () => {
+  assert.equal(formatLoadProgress({ file: "model", loaded: 1, total: 1, fraction: 1 }), "Loading model — 100%");
+});
+
+test("omits byte totals when the server does not provide one", () => {
+  assert.equal(formatLoadProgress({ file: "weights.bin", phase: "download", loaded: 1024, total: 0, fraction: 0 }), "Downloading weights.bin — 0%");
+});