diff --git a/src/ClaudeDo.Installer/Core/IReleaseClient.cs b/src/ClaudeDo.Installer/Core/IReleaseClient.cs
new file mode 100644
index 0000000..8c82449
--- /dev/null
+++ b/src/ClaudeDo.Installer/Core/IReleaseClient.cs
@@ -0,0 +1,15 @@
+namespace ClaudeDo.Installer.Core;
+
+public sealed record ReleaseAsset(string Name, string BrowserDownloadUrl, long Size);
+
+public sealed record GiteaRelease(
+    string TagName,
+    string Name,
+    IReadOnlyList<ReleaseAsset> Assets);
+
+public interface IReleaseClient
+{
+    Task<GiteaRelease?> GetLatestReleaseAsync(CancellationToken ct);
+
+    Task DownloadAsync(string url, string destPath, IProgress<long> progress, CancellationToken ct);
+}
diff --git a/src/ClaudeDo.Installer/Core/ReleaseClient.cs b/src/ClaudeDo.Installer/Core/ReleaseClient.cs
new file mode 100644
index 0000000..4489ea5
--- /dev/null
+++ b/src/ClaudeDo.Installer/Core/ReleaseClient.cs
@@ -0,0 +1,82 @@
+using System.IO;
+using System.Net.Http;
+using System.Text.Json;
+
+namespace ClaudeDo.Installer.Core;
+
+public sealed class ReleaseClient : IReleaseClient
+{
+    public const string DefaultApiBase = "https://git.kuns.dev/api/v1/repos/releases/ClaudeDo";
+
+    private readonly HttpClient _http;
+    private readonly string _apiBase;
+
+    public ReleaseClient(HttpClient http, string apiBase = DefaultApiBase)
+    {
+        _http = http;
+        _apiBase = apiBase.TrimEnd('/');
+    }
+
+    public async Task<GiteaRelease?> GetLatestReleaseAsync(CancellationToken ct)
+    {
+        try
+        {
+            using var response = await _http.GetAsync($"{_apiBase}/releases/latest", ct);
+            if (!response.IsSuccessStatusCode) return null;
+            var json = await response.Content.ReadAsStringAsync(ct);
+            return ParseRelease(json);
+        }
+        catch (HttpRequestException) { return null; }
+        catch (TaskCanceledException) { return null; }
+    }
+
+    public async Task DownloadAsync(string url, string destPath, IProgress<long> progress, CancellationToken ct)
+    {
+        using var response = await _http.GetAsync(url, HttpCompletionOption.ResponseHeadersRead, ct);
+        response.EnsureSuccessStatusCode();
+
+        await using var input = await response.Content.ReadAsStreamAsync(ct);
+        await using var output = File.Create(destPath);
+
+        var buffer = new byte[81920];
+        long total = 0;
+        int read;
+        while ((read = await input.ReadAsync(buffer, ct)) > 0)
+        {
+            await output.WriteAsync(buffer.AsMemory(0, read), ct);
+            total += read;
+            progress.Report(total);
+        }
+    }
+
+    private static GiteaRelease? ParseRelease(string json)
+    {
+        try
+        {
+            using var doc = JsonDocument.Parse(json);
+            var root = doc.RootElement;
+            if (!root.TryGetProperty("tag_name", out var tagEl)) return null;
+
+            var tag = tagEl.GetString() ?? "";
+            var name = root.TryGetProperty("name", out var nameEl) ? (nameEl.GetString() ?? "") : "";
+
+            var assets = new List<ReleaseAsset>();
+            if (root.TryGetProperty("assets", out var arr) && arr.ValueKind == JsonValueKind.Array)
+            {
+                foreach (var item in arr.EnumerateArray())
+                {
+                    var aName = item.GetProperty("name").GetString() ?? "";
+                    var aUrl = item.GetProperty("browser_download_url").GetString() ?? "";
+                    var aSize = item.TryGetProperty("size", out var s) ? s.GetInt64() : 0L;
+                    assets.Add(new ReleaseAsset(aName, aUrl, aSize));
+                }
+            }
+
+            return new GiteaRelease(tag, name, assets);
+        }
+        catch (JsonException)
+        {
+            return null;
+        }
+    }
+}
diff --git a/tests/ClaudeDo.Installer.Tests/ReleaseClientTests.cs b/tests/ClaudeDo.Installer.Tests/ReleaseClientTests.cs
new file mode 100644
index 0000000..954e513
--- /dev/null
+++ b/tests/ClaudeDo.Installer.Tests/ReleaseClientTests.cs
@@ -0,0 +1,109 @@
+using System.Net;
+using System.Net.Http;
+using ClaudeDo.Installer.Core;
+
+namespace ClaudeDo.Installer.Tests;
+
+public sealed class ReleaseClientTests
+{
+    private const string ApiBase = "https://git.example.test/api/v1/repos/releases/ClaudeDo";
+
+    [Fact]
+    public async Task GetLatestReleaseAsync_ParsesTagAndAssets()
+    {
+        const string json = """
+            {
+              "tag_name": "v0.2.0",
+              "name": "v0.2.0",
+              "assets": [
+                {
+                  "name": "ClaudeDo-0.2.0-win-x64.zip",
+                  "browser_download_url": "https://git.example.test/dl/zip",
+                  "size": 12345
+                },
+                {
+                  "name": "checksums.txt",
+                  "browser_download_url": "https://git.example.test/dl/checksums",
+                  "size": 128
+                }
+              ]
+            }
+            """;
+
+        var handler = new FakeHttpMessageHandler(HttpStatusCode.OK, json);
+        using var http = new HttpClient(handler);
+        var client = new ReleaseClient(http, ApiBase);
+
+        var release = await client.GetLatestReleaseAsync(CancellationToken.None);
+
+        Assert.NotNull(release);
+        Assert.Equal("v0.2.0", release!.TagName);
+        Assert.Equal(2, release.Assets.Count);
+        Assert.Equal("ClaudeDo-0.2.0-win-x64.zip", release.Assets[0].Name);
+        Assert.Equal("https://git.example.test/dl/zip", release.Assets[0].BrowserDownloadUrl);
+        Assert.Equal(12345, release.Assets[0].Size);
+    }
+
+    [Fact]
+    public async Task GetLatestReleaseAsync_Returns_Null_On404()
+    {
+        var handler = new FakeHttpMessageHandler(HttpStatusCode.NotFound, "");
+        using var http = new HttpClient(handler);
+        var client = new ReleaseClient(http, ApiBase);
+
+        var release = await client.GetLatestReleaseAsync(CancellationToken.None);
+
+        Assert.Null(release);
+    }
+
+    [Fact]
+    public async Task GetLatestReleaseAsync_Returns_Null_OnNetworkError()
+    {
+        var handler = new FakeHttpMessageHandler(_ => throw new HttpRequestException("boom"));
+        using var http = new HttpClient(handler);
+        var client = new ReleaseClient(http, ApiBase);
+
+        var release = await client.GetLatestReleaseAsync(CancellationToken.None);
+
+        Assert.Null(release);
+    }
+
+    [Fact]
+    public async Task GetLatestReleaseAsync_Hits_CorrectUrl()
+    {
+        var handler = new FakeHttpMessageHandler(HttpStatusCode.OK, "{\"tag_name\":\"v0.1.0\",\"assets\":[]}");
+        using var http = new HttpClient(handler);
+        var client = new ReleaseClient(http, ApiBase);
+
+        _ = await client.GetLatestReleaseAsync(CancellationToken.None);
+
+        Assert.Single(handler.Requests);
+        Assert.Equal($"{ApiBase}/releases/latest", handler.Requests[0].RequestUri!.ToString());
+    }
+
+    [Fact]
+    public async Task DownloadAsync_WritesBytesToDisk()
+    {
+        var payload = new byte[] { 1, 2, 3, 4, 5 };
+        var handler = new FakeHttpMessageHandler(_ => new HttpResponseMessage(HttpStatusCode.OK)
+        {
+            Content = new ByteArrayContent(payload)
+        });
+        using var http = new HttpClient(handler);
+        var client = new ReleaseClient(http, ApiBase);
+
+        var tempPath = Path.Combine(Path.GetTempPath(), "ClaudeDoDlTest-" + Guid.NewGuid().ToString("N"));
+        try
+        {
+            await client.DownloadAsync("https://example/foo", tempPath,
+                new Progress<long>(_ => { }), CancellationToken.None);
+
+            Assert.True(File.Exists(tempPath));
+            Assert.Equal(payload, File.ReadAllBytes(tempPath));
+        }
+        finally
+        {
+            if (File.Exists(tempPath)) File.Delete(tempPath);
+        }
+    }
+}