refactor(kernel): report kernel download progress through the sink

get_default_kernel emits Progress events for the APK transfer instead
of drawing a bar to stderr from inside the library.

crates/ecr-cli/src/main.rs

@@ -63,7 +63,7 @@ fn main() -> Result<()> {
             }
             None => {
                 veprintln!("QEMU mode: downloading default kernel...");
-                kernel::get_default_kernel(cache.dir(), &arch)?
+                kernel::get_default_kernel(cache.dir(), &arch, &ecr::NoProgress)?
             }
         };
 

crates/ecr/src/kernel.rs

@@ -17,9 +17,9 @@
 //! kernel image gzipped, and QEMU's riscv `-kernel` loader understands
 //! only ELF, uImage and raw images.
 
+use crate::progress::{Progress, Unit};
 use crate::veprintln;
 use anyhow::{anyhow, Context, Result};
-use indicatif::{ProgressBar, ProgressStyle};
 use std::io::{Read, Seek};
 use std::path::{Path, PathBuf};
 use std::time::Duration;
@@ -237,7 +237,12 @@ fn find_kernel_package(branch: &str, arch: &str) -> Result<(&'static str, String
 }
 
 /// Download and extract the kernel from an Alpine package repository
-fn download_alpine_kernel(branch: &str, arch: &str, dest: &Path) -> Result<()> {
+fn download_alpine_kernel(
+    branch: &str,
+    arch: &str,
+    dest: &Path,
+    progress: &dyn Progress,
+) -> Result<()> {
     let (package, version) = find_kernel_package(branch, arch)?;
     veprintln!("Found {} version: {}", package, version);
 
@@ -252,7 +257,7 @@ fn download_alpine_kernel(branch: &str, arch: &str, dest: &Path) -> Result<()> {
 
     // Use async download via the existing download module pattern
     let rt = tokio::runtime::Runtime::new().context("Failed to create Tokio runtime")?;
-    rt.block_on(download_kernel_async(&url, dest))?;
+    rt.block_on(download_kernel_async(&url, dest, progress))?;
 
     // Extract the kernel image from the APK, then store it decompressed.
     // Remove the ~45MB APK whatever the outcome — don't leave it behind
@@ -264,7 +269,7 @@ fn download_alpine_kernel(branch: &str, arch: &str, dest: &Path) -> Result<()> {
     result
 }
 
-async fn download_kernel_async(url: &str, dest: &Path) -> Result<()> {
+async fn download_kernel_async(url: &str, dest: &Path, progress: &dyn Progress) -> Result<()> {
     use futures_util::StreamExt;
     let client = reqwest::Client::builder()
         .timeout(Duration::from_secs(300))
@@ -286,13 +291,10 @@ async fn download_kernel_async(url: &str, dest: &Path) -> Result<()> {
 
     let total_size = response.content_length().unwrap_or(0);
 
-    // Setup progress bar
-    let pb = ProgressBar::new(total_size);
-    pb.set_style(
-        ProgressStyle::default_bar()
-            .template("{spinner:.green} [{elapsed_precise}] [{bar:40.cyan/blue}] {bytes}/{total_bytes} ({eta})")
-            .unwrap()
-            .progress_chars("#>-"),
+    progress.begin(
+        "Downloading kernel",
+        Unit::Bytes,
+        (total_size > 0).then_some(total_size),
     );
 
     let temp_apk = dest.with_extension("apk.partial");
@@ -300,7 +302,6 @@ async fn download_kernel_async(url: &str, dest: &Path) -> Result<()> {
         .await
         .context("Failed to create temp APK file")?;
 
-    let mut downloaded: u64 = 0;
     let mut stream = response.bytes_stream();
 
     while let Some(chunk) = stream.next().await {
@@ -308,15 +309,14 @@ async fn download_kernel_async(url: &str, dest: &Path) -> Result<()> {
         tokio::io::AsyncWriteExt::write_all(&mut file, &chunk)
             .await
             .context("Failed to write chunk")?;
-        downloaded += chunk.len() as u64;
-        pb.set_position(downloaded);
+        progress.advance(chunk.len() as u64);
     }
 
     tokio::io::AsyncWriteExt::flush(&mut file)
         .await
         .context("Failed to flush file")?;
 
-    pb.finish_with_message("Download complete");
+    progress.finish();
 
     // Rename to final name
     let final_apk = dest.with_extension("apk");
@@ -392,8 +392,13 @@ fn decompress_kernel_if_gzipped(path: &Path) -> Result<()> {
 }
 
 /// Get the path to the cached default kernel for the given architecture.
-/// Downloads and caches it if not present.
-pub fn get_default_kernel(cache_dir: &Path, arch: &str) -> Result<PathBuf> {
+/// Downloads and caches it if not present, reporting download progress
+/// through `progress`.
+pub fn get_default_kernel(
+    cache_dir: &Path,
+    arch: &str,
+    progress: &dyn Progress,
+) -> Result<PathBuf> {
     let alpine_arch = alpine_kernel_arch(arch);
 
     // Cache filename includes architecture
@@ -414,7 +419,7 @@ pub fn get_default_kernel(cache_dir: &Path, arch: &str) -> Result<PathBuf> {
     veprintln!("Using Alpine branch: {}", branch);
 
     // Download and extract the kernel
-    download_alpine_kernel(&branch, alpine_arch, &kernel_path)?;
+    download_alpine_kernel(&branch, alpine_arch, &kernel_path, progress)?;
 
     Ok(kernel_path)
 }