diff --git a/src/ClaudeDo.Worker/Report/Interfaces/IClaudeHistoryReader.cs b/src/ClaudeDo.Worker/Report/Interfaces/IClaudeHistoryReader.cs
new file mode 100644
index 0000000..c1bea07
--- /dev/null
+++ b/src/ClaudeDo.Worker/Report/Interfaces/IClaudeHistoryReader.cs
@@ -0,0 +1,10 @@
+namespace ClaudeDo.Worker.Report.Interfaces;
+
+public interface IClaudeHistoryReader
+{
+    Task<IReadOnlyList<RepoActivity>> ReadAsync(
+        DateOnly start,
+        DateOnly end,
+        IReadOnlyList<string> excludedPrefixes,
+        CancellationToken ct = default);
+}
diff --git a/src/ClaudeDo.Worker/Report/ReportModels.cs b/src/ClaudeDo.Worker/Report/ReportModels.cs
new file mode 100644
index 0000000..01cc5ff
--- /dev/null
+++ b/src/ClaudeDo.Worker/Report/ReportModels.cs
@@ -0,0 +1,14 @@
+namespace ClaudeDo.Worker.Report;
+
+public sealed class DayActivity
+{
+    public DateOnly Date { get; init; }
+    public List<string> Prompts { get; } = new();
+    public List<string> Summaries { get; } = new();
+}
+
+public sealed class RepoActivity
+{
+    public required string RepoPath { get; init; }
+    public List<DayActivity> Days { get; } = new();
+}