diff --git a/SharepointToolbox.Tests/Services/DuplicatesServiceTests.cs b/SharepointToolbox.Tests/Services/DuplicatesServiceTests.cs
new file mode 100644
index 0000000..4798d23
--- /dev/null
+++ b/SharepointToolbox.Tests/Services/DuplicatesServiceTests.cs
@@ -0,0 +1,80 @@
+using SharepointToolbox.Core.Models;
+using SharepointToolbox.Services;
+using Xunit;
+
+namespace SharepointToolbox.Tests.Services;
+
+/// <summary>
+/// Pure-logic tests for the MakeKey composite key function (no CSOM needed).
+/// Inline helper matches the implementation DuplicatesService will produce in Plan 03-04.
+/// </summary>
+public class DuplicatesServiceTests
+{
+    // Inline copy of MakeKey to test logic before Plan 03-04 creates the real class
+    private static string MakeKey(DuplicateItem item, DuplicateScanOptions opts)
+    {
+        var parts = new System.Collections.Generic.List<string> { item.Name.ToLowerInvariant() };
+        if (opts.MatchSize     && item.SizeBytes.HasValue)    parts.Add(item.SizeBytes.Value.ToString());
+        if (opts.MatchCreated  && item.Created.HasValue)      parts.Add(item.Created.Value.Date.ToString("yyyy-MM-dd"));
+        if (opts.MatchModified && item.Modified.HasValue)     parts.Add(item.Modified.Value.Date.ToString("yyyy-MM-dd"));
+        if (opts.MatchSubfolderCount && item.FolderCount.HasValue) parts.Add(item.FolderCount.Value.ToString());
+        if (opts.MatchFileCount && item.FileCount.HasValue)   parts.Add(item.FileCount.Value.ToString());
+        return string.Join("|", parts);
+    }
+
+    [Fact]
+    public void MakeKey_NameOnly_ReturnsLowercaseName()
+    {
+        var item = new DuplicateItem { Name = "Report.docx", SizeBytes = 1000 };
+        var opts = new DuplicateScanOptions(MatchSize: false);
+        Assert.Equal("report.docx", MakeKey(item, opts));
+    }
+
+    [Fact]
+    public void MakeKey_WithSizeMatch_AppendsSizeToKey()
+    {
+        var item = new DuplicateItem { Name = "Report.docx", SizeBytes = 1024 };
+        var opts = new DuplicateScanOptions(MatchSize: true);
+        Assert.Equal("report.docx|1024", MakeKey(item, opts));
+    }
+
+    [Fact]
+    public void MakeKey_WithCreatedAndModified_AppendsDateStrings()
+    {
+        var item = new DuplicateItem
+        {
+            Name = "file.pdf",
+            SizeBytes = 500,
+            Created = new DateTime(2024, 3, 15),
+            Modified = new DateTime(2024, 6, 1)
+        };
+        var opts = new DuplicateScanOptions(MatchSize: false, MatchCreated: true, MatchModified: true);
+        Assert.Equal("file.pdf|2024-03-15|2024-06-01", MakeKey(item, opts));
+    }
+
+    [Fact]
+    public void MakeKey_SameKeyForSameItems_GroupsCorrectly()
+    {
+        var opts = new DuplicateScanOptions(MatchSize: true);
+        var item1 = new DuplicateItem { Name = "Budget.xlsx", SizeBytes = 2048 };
+        var item2 = new DuplicateItem { Name = "BUDGET.xlsx", SizeBytes = 2048 };
+        Assert.Equal(MakeKey(item1, opts), MakeKey(item2, opts));
+    }
+
+    [Fact]
+    public void MakeKey_DifferentSize_ProducesDifferentKeys()
+    {
+        var opts = new DuplicateScanOptions(MatchSize: true);
+        var item1 = new DuplicateItem { Name = "file.docx", SizeBytes = 100 };
+        var item2 = new DuplicateItem { Name = "file.docx", SizeBytes = 200 };
+        Assert.NotEqual(MakeKey(item1, opts), MakeKey(item2, opts));
+    }
+
+    [Fact(Skip = "Requires live CSOM context — covered by Plan 03-04 implementation")]
+    public Task ScanDuplicatesAsync_Files_GroupsByCompositeKey()
+        => Task.CompletedTask;
+
+    [Fact(Skip = "Requires live CSOM context — covered by Plan 03-04 implementation")]
+    public Task ScanDuplicatesAsync_Folders_UsesCamlFSObjType1()
+        => Task.CompletedTask;
+}
diff --git a/SharepointToolbox.Tests/Services/Export/DuplicatesHtmlExportServiceTests.cs b/SharepointToolbox.Tests/Services/Export/DuplicatesHtmlExportServiceTests.cs
new file mode 100644
index 0000000..c1af935
--- /dev/null
+++ b/SharepointToolbox.Tests/Services/Export/DuplicatesHtmlExportServiceTests.cs
@@ -0,0 +1,53 @@
+using SharepointToolbox.Core.Models;
+using SharepointToolbox.Services.Export;
+using Xunit;
+
+namespace SharepointToolbox.Tests.Services.Export;
+
+public class DuplicatesHtmlExportServiceTests
+{
+    private static DuplicateGroup MakeGroup(string name, int count) => new()
+    {
+        GroupKey = $"{name}|1024",
+        Name = name,
+        Items = Enumerable.Range(1, count).Select(i => new DuplicateItem
+        {
+            Name = name,
+            Path = $"https://contoso.sharepoint.com/sites/Site{i}/{name}",
+            Library = "Shared Documents",
+            SizeBytes = 1024
+        }).ToList()
+    };
+
+    [Fact]
+    public void BuildHtml_WithGroups_ContainsGroupCards()
+    {
+        var svc = new DuplicatesHtmlExportService();
+        var groups = new List<DuplicateGroup> { MakeGroup("report.docx", 3) };
+        var html = svc.BuildHtml(groups);
+        Assert.Contains("<!DOCTYPE html>", html);
+        Assert.Contains("report.docx", html);
+    }
+
+    [Fact]
+    public void BuildHtml_WithMultipleGroups_AllGroupNamesPresent()
+    {
+        var svc = new DuplicatesHtmlExportService();
+        var groups = new List<DuplicateGroup>
+        {
+            MakeGroup("budget.xlsx", 2),
+            MakeGroup("photo.jpg", 4)
+        };
+        var html = svc.BuildHtml(groups);
+        Assert.Contains("budget.xlsx", html);
+        Assert.Contains("photo.jpg", html);
+    }
+
+    [Fact]
+    public void BuildHtml_WithEmptyList_ReturnsValidHtml()
+    {
+        var svc = new DuplicatesHtmlExportService();
+        var html = svc.BuildHtml(new List<DuplicateGroup>());
+        Assert.Contains("<!DOCTYPE html>", html);
+    }
+}
diff --git a/SharepointToolbox.Tests/Services/Export/SearchExportServiceTests.cs b/SharepointToolbox.Tests/Services/Export/SearchExportServiceTests.cs
new file mode 100644
index 0000000..bf63a09
--- /dev/null
+++ b/SharepointToolbox.Tests/Services/Export/SearchExportServiceTests.cs
@@ -0,0 +1,82 @@
+using SharepointToolbox.Core.Models;
+using SharepointToolbox.Services.Export;
+using Xunit;
+
+namespace SharepointToolbox.Tests.Services.Export;
+
+public class SearchExportServiceTests
+{
+    private static SearchResult MakeSample() => new()
+    {
+        Title = "Q1 Budget.xlsx",
+        Path = "https://contoso.sharepoint.com/sites/Finance/Shared Documents/Q1 Budget.xlsx",
+        FileExtension = "xlsx",
+        Created = new DateTime(2024, 1, 10),
+        LastModified = new DateTime(2024, 3, 20),
+        Author = "Alice Smith",
+        ModifiedBy = "Bob Jones",
+        SizeBytes = 48_000
+    };
+
+    // -- CSV tests -----------------------------------------------------------
+
+    [Fact]
+    public void BuildCsv_WithKnownResults_ContainsExpectedHeader()
+    {
+        var svc = new SearchCsvExportService();
+        var csv = svc.BuildCsv(new List<SearchResult> { MakeSample() });
+        Assert.Contains("File Name", csv);
+        Assert.Contains("Extension", csv);
+        Assert.Contains("Created", csv);
+        Assert.Contains("Created By", csv);
+        Assert.Contains("Modified By", csv);
+        Assert.Contains("Size", csv);
+    }
+
+    [Fact]
+    public void BuildCsv_WithEmptyList_ReturnsHeaderOnly()
+    {
+        var svc = new SearchCsvExportService();
+        var csv = svc.BuildCsv(new List<SearchResult>());
+        Assert.NotEmpty(csv);
+        var lines = csv.Split('\n', StringSplitOptions.RemoveEmptyEntries);
+        Assert.Single(lines);
+    }
+
+    [Fact]
+    public void BuildCsv_ResultValues_AppearInOutput()
+    {
+        var svc = new SearchCsvExportService();
+        var csv = svc.BuildCsv(new List<SearchResult> { MakeSample() });
+        Assert.Contains("Alice Smith", csv);
+        Assert.Contains("xlsx", csv);
+    }
+
+    // -- HTML tests ----------------------------------------------------------
+
+    [Fact]
+    public void BuildHtml_WithResults_ContainsSortableColumnScript()
+    {
+        var svc = new SearchHtmlExportService();
+        var html = svc.BuildHtml(new List<SearchResult> { MakeSample() });
+        Assert.Contains("<!DOCTYPE html>", html);
+        Assert.Contains("sort", html);          // sortable columns JS
+        Assert.Contains("Q1 Budget.xlsx", html);
+    }
+
+    [Fact]
+    public void BuildHtml_WithResults_ContainsFilterInput()
+    {
+        var svc = new SearchHtmlExportService();
+        var html = svc.BuildHtml(new List<SearchResult> { MakeSample() });
+        Assert.Contains("filter", html);        // filter input element
+    }
+
+    [Fact]
+    public void BuildHtml_WithEmptyList_ReturnsValidHtml()
+    {
+        var svc = new SearchHtmlExportService();
+        var html = svc.BuildHtml(new List<SearchResult>());
+        Assert.Contains("<!DOCTYPE html>", html);
+    }
+}
diff --git a/SharepointToolbox.Tests/Services/Export/StorageCsvExportServiceTests.cs b/SharepointToolbox.Tests/Services/Export/StorageCsvExportServiceTests.cs
new file mode 100644
index 0000000..8caef66
--- /dev/null
+++ b/SharepointToolbox.Tests/Services/Export/StorageCsvExportServiceTests.cs
@@ -0,0 +1,52 @@
+using SharepointToolbox.Core.Models;
+using SharepointToolbox.Services.Export;
+using Xunit;
+
+namespace SharepointToolbox.Tests.Services.Export;
+
+public class StorageCsvExportServiceTests
+{
+    [Fact]
+    public void BuildCsv_WithKnownNodes_ProducesHeaderRow()
+    {
+        var svc = new StorageCsvExportService();
+        var nodes = new List<StorageNode>
+        {
+            new() { Name = "Shared Documents", Library = "Shared Documents", SiteTitle = "MySite",
+                    TotalSizeBytes = 1024, FileStreamSizeBytes = 800, TotalFileCount = 5,
+                    LastModified = new DateTime(2024, 1, 15) }
+        };
+        var csv = svc.BuildCsv(nodes);
+        Assert.Contains("Library", csv);
+        Assert.Contains("Site", csv);
+        Assert.Contains("Files", csv);
+        Assert.Contains("Total Size", csv);
+        Assert.Contains("Version Size", csv);
+        Assert.Contains("Last Modified", csv);
+    }
+
+    [Fact]
+    public void BuildCsv_WithEmptyList_ReturnsHeaderOnly()
+    {
+        var svc = new StorageCsvExportService();
+        var csv = svc.BuildCsv(new List<StorageNode>());
+        Assert.NotEmpty(csv); // must have at least the header row
+        var lines = csv.Split('\n', StringSplitOptions.RemoveEmptyEntries);
+        Assert.Single(lines); // only header, no data rows
+    }
+
+    [Fact]
+    public void BuildCsv_NodeValues_AppearInOutput()
+    {
+        var svc = new StorageCsvExportService();
+        var nodes = new List<StorageNode>
+        {
+            new() { Name = "Reports", Library = "Reports", SiteTitle = "ProjectSite",
+                    TotalSizeBytes = 2048, FileStreamSizeBytes = 1024, TotalFileCount = 10 }
+        };
+        var csv = svc.BuildCsv(nodes);
+        Assert.Contains("Reports", csv);
+        Assert.Contains("ProjectSite", csv);
+        Assert.Contains("10", csv);
+    }
+}
diff --git a/SharepointToolbox.Tests/Services/Export/StorageHtmlExportServiceTests.cs b/SharepointToolbox.Tests/Services/Export/StorageHtmlExportServiceTests.cs
new file mode 100644
index 0000000..ec98c9b
--- /dev/null
+++ b/SharepointToolbox.Tests/Services/Export/StorageHtmlExportServiceTests.cs
@@ -0,0 +1,51 @@
+using SharepointToolbox.Core.Models;
+using SharepointToolbox.Services.Export;
+using Xunit;
+
+namespace SharepointToolbox.Tests.Services.Export;
+
+public class StorageHtmlExportServiceTests
+{
+    [Fact]
+    public void BuildHtml_WithNodes_ContainsToggleJs()
+    {
+        var svc = new StorageHtmlExportService();
+        var nodes = new List<StorageNode>
+        {
+            new() { Name = "Shared Documents", Library = "Shared Documents", SiteTitle = "Site1",
+                    TotalSizeBytes = 5000, FileStreamSizeBytes = 4000, TotalFileCount = 20,
+                    Children = new List<StorageNode>
+                    {
+                        new() { Name = "Archive", Library = "Shared Documents", SiteTitle = "Site1",
+                                TotalSizeBytes = 1000, FileStreamSizeBytes = 800, TotalFileCount = 5 }
+                    } }
+        };
+        var html = svc.BuildHtml(nodes);
+        Assert.Contains("toggle(", html);
+        Assert.Contains("<!DOCTYPE html>", html);
+        Assert.Contains("Shared Documents", html);
+    }
+
+    [Fact]
+    public void BuildHtml_WithEmptyList_ReturnsValidHtml()
+    {
+        var svc = new StorageHtmlExportService();
+        var html = svc.BuildHtml(new List<StorageNode>());
+        Assert.Contains("<!DOCTYPE html>", html);
+        Assert.Contains("<html", html);
+    }
+
+    [Fact]
+    public void BuildHtml_WithMultipleLibraries_EachLibraryAppearsInOutput()
+    {
+        var svc = new StorageHtmlExportService();
+        var nodes = new List<StorageNode>
+        {
+            new() { Name = "Documents", Library = "Documents", SiteTitle = "Site1", TotalSizeBytes = 1000 },
+            new() { Name = "Images", Library = "Images", SiteTitle = "Site1", TotalSizeBytes = 2000 }
+        };
+        var html = svc.BuildHtml(nodes);
+        Assert.Contains("Documents", html);
+        Assert.Contains("Images", html);
+    }
+}
diff --git a/SharepointToolbox.Tests/Services/SearchServiceTests.cs b/SharepointToolbox.Tests/Services/SearchServiceTests.cs
new file mode 100644
index 0000000..b771ad2
--- /dev/null
+++ b/SharepointToolbox.Tests/Services/SearchServiceTests.cs
@@ -0,0 +1,20 @@
+using SharepointToolbox.Core.Models;
+using SharepointToolbox.Services;
+using Xunit;
+
+namespace SharepointToolbox.Tests.Services;
+
+public class SearchServiceTests
+{
+    [Fact(Skip = "Requires live CSOM context — covered by Plan 03-04 implementation")]
+    public Task SearchFilesAsync_WithExtensionFilter_BuildsCorrectKql()
+        => Task.CompletedTask;
+
+    [Fact(Skip = "Requires live CSOM context — covered by Plan 03-04 implementation")]
+    public Task SearchFilesAsync_PaginationStopsAt50000()
+        => Task.CompletedTask;
+
+    [Fact(Skip = "Requires live CSOM context — covered by Plan 03-04 implementation")]
+    public Task SearchFilesAsync_FiltersVersionHistoryPaths()
+        => Task.CompletedTask;
+}
diff --git a/SharepointToolbox.Tests/Services/StorageServiceTests.cs b/SharepointToolbox.Tests/Services/StorageServiceTests.cs
new file mode 100644
index 0000000..ed8e3a7
--- /dev/null
+++ b/SharepointToolbox.Tests/Services/StorageServiceTests.cs
@@ -0,0 +1,31 @@
+using SharepointToolbox.Core.Models;
+using SharepointToolbox.Services;
+using Xunit;
+
+namespace SharepointToolbox.Tests.Services;
+
+public class StorageServiceTests
+{
+    [Fact(Skip = "Requires live CSOM context — covered by Plan 03-02 implementation")]
+    public Task CollectStorageAsync_ReturnsLibraryNodes_ForDocumentLibraries()
+        => Task.CompletedTask;
+
+    [Fact(Skip = "Requires live CSOM context — covered by Plan 03-02 implementation")]
+    public Task CollectStorageAsync_WithFolderDepth1_ReturnsSubfolderNodes()
+        => Task.CompletedTask;
+
+    [Fact]
+    public void StorageNode_VersionSizeBytes_IsNonNegative()
+    {
+        // VersionSizeBytes = TotalSizeBytes - FileStreamSizeBytes (never negative)
+        var node = new StorageNode { TotalSizeBytes = 1000L, FileStreamSizeBytes = 1200L };
+        Assert.Equal(0L, node.VersionSizeBytes); // Math.Max(0, -200) = 0
+    }
+
+    [Fact]
+    public void StorageNode_VersionSizeBytes_IsCorrectWhenPositive()
+    {
+        var node = new StorageNode { TotalSizeBytes = 5000L, FileStreamSizeBytes = 3000L };
+        Assert.Equal(2000L, node.VersionSizeBytes);
+    }
+}
diff --git a/SharepointToolbox/Services/Export/DuplicatesHtmlExportService.cs b/SharepointToolbox/Services/Export/DuplicatesHtmlExportService.cs
new file mode 100644
index 0000000..3376a86
--- /dev/null
+++ b/SharepointToolbox/Services/Export/DuplicatesHtmlExportService.cs
@@ -0,0 +1,14 @@
+using SharepointToolbox.Core.Models;
+
+namespace SharepointToolbox.Services.Export;
+
+public class DuplicatesHtmlExportService
+{
+    public string BuildHtml(IReadOnlyList<DuplicateGroup> groups) => string.Empty; // implemented in Plan 03-05
+
+    public async Task WriteAsync(IReadOnlyList<DuplicateGroup> groups, string filePath, CancellationToken ct)
+    {
+        var html = BuildHtml(groups);
+        await System.IO.File.WriteAllTextAsync(filePath, html, System.Text.Encoding.UTF8, ct);
+    }
+}
diff --git a/SharepointToolbox/Services/Export/SearchCsvExportService.cs b/SharepointToolbox/Services/Export/SearchCsvExportService.cs
new file mode 100644
index 0000000..95fb036
--- /dev/null
+++ b/SharepointToolbox/Services/Export/SearchCsvExportService.cs
@@ -0,0 +1,14 @@
+using SharepointToolbox.Core.Models;
+
+namespace SharepointToolbox.Services.Export;
+
+public class SearchCsvExportService
+{
+    public string BuildCsv(IReadOnlyList<SearchResult> results) => string.Empty; // implemented in Plan 03-05
+
+    public async Task WriteAsync(IReadOnlyList<SearchResult> results, string filePath, CancellationToken ct)
+    {
+        var csv = BuildCsv(results);
+        await System.IO.File.WriteAllTextAsync(filePath, csv, new System.Text.UTF8Encoding(true), ct);
+    }
+}
diff --git a/SharepointToolbox/Services/Export/SearchHtmlExportService.cs b/SharepointToolbox/Services/Export/SearchHtmlExportService.cs
new file mode 100644
index 0000000..67df080
--- /dev/null
+++ b/SharepointToolbox/Services/Export/SearchHtmlExportService.cs
@@ -0,0 +1,14 @@
+using SharepointToolbox.Core.Models;
+
+namespace SharepointToolbox.Services.Export;
+
+public class SearchHtmlExportService
+{
+    public string BuildHtml(IReadOnlyList<SearchResult> results) => string.Empty; // implemented in Plan 03-05
+
+    public async Task WriteAsync(IReadOnlyList<SearchResult> results, string filePath, CancellationToken ct)
+    {
+        var html = BuildHtml(results);
+        await System.IO.File.WriteAllTextAsync(filePath, html, System.Text.Encoding.UTF8, ct);
+    }
+}
diff --git a/SharepointToolbox/Services/Export/StorageCsvExportService.cs b/SharepointToolbox/Services/Export/StorageCsvExportService.cs
new file mode 100644
index 0000000..a42b619
--- /dev/null
+++ b/SharepointToolbox/Services/Export/StorageCsvExportService.cs
@@ -0,0 +1,14 @@
+using SharepointToolbox.Core.Models;
+
+namespace SharepointToolbox.Services.Export;
+
+public class StorageCsvExportService
+{
+    public string BuildCsv(IReadOnlyList<StorageNode> nodes) => string.Empty; // implemented in Plan 03-03
+
+    public async Task WriteAsync(IReadOnlyList<StorageNode> nodes, string filePath, CancellationToken ct)
+    {
+        var csv = BuildCsv(nodes);
+        await System.IO.File.WriteAllTextAsync(filePath, csv, new System.Text.UTF8Encoding(true), ct);
+    }
+}
diff --git a/SharepointToolbox/Services/Export/StorageHtmlExportService.cs b/SharepointToolbox/Services/Export/StorageHtmlExportService.cs
new file mode 100644
index 0000000..3818d42
--- /dev/null
+++ b/SharepointToolbox/Services/Export/StorageHtmlExportService.cs
@@ -0,0 +1,14 @@
+using SharepointToolbox.Core.Models;
+
+namespace SharepointToolbox.Services.Export;
+
+public class StorageHtmlExportService
+{
+    public string BuildHtml(IReadOnlyList<StorageNode> nodes) => string.Empty; // implemented in Plan 03-03
+
+    public async Task WriteAsync(IReadOnlyList<StorageNode> nodes, string filePath, CancellationToken ct)
+    {
+        var html = BuildHtml(nodes);
+        await System.IO.File.WriteAllTextAsync(filePath, html, System.Text.Encoding.UTF8, ct);
+    }
+}