diff --git a/.github/workflows/LANCommander.Launcher.Avalonia.Visual.yml b/.github/workflows/LANCommander.Launcher.Avalonia.Visual.yml
new file mode 100644
index 00000000..a1549437
--- /dev/null
+++ b/.github/workflows/LANCommander.Launcher.Avalonia.Visual.yml
@@ -0,0 +1,254 @@
+name: Avalonia Launcher Visual Tests
+
+# ---------------------------------------------------------------------------
+# Triggers
+# ---------------------------------------------------------------------------
+on:
+  pull_request:
+    branches: [main]
+    paths:
+      - 'LANCommander.Launcher.Avalonia/**'
+      - 'LANCommander.Launcher.Avalonia.Tests/**'
+
+  push:
+    branches: [main]
+    paths:
+      - 'LANCommander.Launcher.Avalonia/**'
+      - 'LANCommander.Launcher.Avalonia.Tests/**'
+
+  # Manual dispatch: re-run tests and optionally commit updated baselines.
+  workflow_dispatch:
+    inputs:
+      update_baselines:
+        description: 'Commit updated baselines back to the branch (use after intentional UI changes)'
+        type: boolean
+        default: false
+
+# ---------------------------------------------------------------------------
+# Permissions
+# ---------------------------------------------------------------------------
+permissions:
+  contents: write      # allow committing updated baselines
+  pull-requests: write # allow posting PR comments
+
+# ---------------------------------------------------------------------------
+# Jobs
+# ---------------------------------------------------------------------------
+jobs:
+  visual-tests:
+    # Self-hosted runner required: needs access to your local LANCommander server
+    # so that any future integration tests can connect and capture live screenshots.
+    # Tag your runner with 'lancommander' in GitHub → Settings → Actions → Runners.
+    runs-on: [self-hosted, lancommander]
+
+    env:
+      DOTNET_NOLOGO: true
+      DOTNET_CLI_TELEMETRY_OPTOUT: true
+      NUGET_PACKAGES: ${{ github.workspace }}/.nuget/packages
+
+      # Paths used by ScreenshotHelper — relative to workspace so artifacts are easy to find.
+      VISUAL_SCREENSHOTS_DIR: ${{ github.workspace }}/visual-test-output/screenshots
+      VISUAL_DIFFS_DIR:       ${{ github.workspace }}/visual-test-output/diffs
+      # Baselines are loaded from the build output (copied from Baselines/ content items).
+      # Override this var only if you move the Baselines folder.
+
+    steps:
+      # -----------------------------------------------------------------------
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          submodules: true
+          # Fetch all history so we can commit baseline updates.
+          fetch-depth: 0
+
+      # -----------------------------------------------------------------------
+      - name: Setup .NET
+        uses: actions/setup-dotnet@v4
+        with:
+          dotnet-version: '9.0.x'
+
+      # -----------------------------------------------------------------------
+      - name: Cache NuGet packages
+        uses: actions/cache@v4
+        with:
+          path: ${{ env.NUGET_PACKAGES }}
+          key: nuget-${{ runner.os }}-${{ hashFiles('**/Directory.Packages.props', '**/*.csproj') }}
+          restore-keys: |
+            nuget-${{ runner.os }}-
+
+      # -----------------------------------------------------------------------
+      - name: Restore dependencies
+        run: dotnet restore --locked-mode
+
+      # -----------------------------------------------------------------------
+      - name: Build test project
+        run: |
+          dotnet build LANCommander.Launcher.Avalonia.Tests/ \
+            --no-restore \
+            --configuration Release
+
+      # -----------------------------------------------------------------------
+      - name: Run visual layout tests
+        id: run-tests
+        # continue-on-error so we can still upload artifacts and post a PR comment
+        # even when tests fail.  The final step re-raises the failure.
+        continue-on-error: true
+        run: |
+          dotnet test LANCommander.Launcher.Avalonia.Tests/ \
+            --no-build \
+            --configuration Release \
+            --logger "trx;LogFileName=${{ github.workspace }}/visual-test-results.trx" \
+            --logger "console;verbosity=normal"
+
+      # -----------------------------------------------------------------------
+      # Always upload screenshots + diffs so you can review what the UI looked
+      # like during this run, regardless of pass/fail.
+      - name: Upload screenshots
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: visual-screenshots-${{ github.sha }}
+          path: ${{ env.VISUAL_SCREENSHOTS_DIR }}/
+          if-no-files-found: ignore
+
+      - name: Upload diff images
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: visual-diffs-${{ github.sha }}
+          path: ${{ env.VISUAL_DIFFS_DIR }}/
+          if-no-files-found: ignore
+
+      - name: Upload test results
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: visual-test-results-${{ github.sha }}
+          path: visual-test-results.trx
+          if-no-files-found: ignore
+
+      # -----------------------------------------------------------------------
+      # Write a step summary that shows the pass/fail status and links to artifacts.
+      - name: Write step summary
+        if: always()
+        shell: bash
+        run: |
+          STATUS="${{ steps.run-tests.outcome }}"
+          echo "## Avalonia Visual Test Results" >> $GITHUB_STEP_SUMMARY
+          echo "" >> $GITHUB_STEP_SUMMARY
+          if [ "$STATUS" = "success" ]; then
+            echo "✅ All visual tests passed — no regressions detected." >> $GITHUB_STEP_SUMMARY
+          else
+            echo "❌ Visual regressions detected (or new baselines need to be committed)." >> $GITHUB_STEP_SUMMARY
+            echo "" >> $GITHUB_STEP_SUMMARY
+            echo "**Next steps:**" >> $GITHUB_STEP_SUMMARY
+            echo "1. Download the **visual-screenshots** and **visual-diffs** artifacts to review changes." >> $GITHUB_STEP_SUMMARY
+            echo "2. If the changes are intentional, run the workflow manually with **Update baselines** checked." >> $GITHUB_STEP_SUMMARY
+            echo "3. If the changes are regressions, fix the layout before merging." >> $GITHUB_STEP_SUMMARY
+          fi
+          echo "" >> $GITHUB_STEP_SUMMARY
+          echo "| Artifact | Link |" >> $GITHUB_STEP_SUMMARY
+          echo "|---|---|" >> $GITHUB_STEP_SUMMARY
+          echo "| Screenshots | [visual-screenshots-${{ github.sha }}](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}) |" >> $GITHUB_STEP_SUMMARY
+          echo "| Diff images | [visual-diffs-${{ github.sha }}](${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}) |" >> $GITHUB_STEP_SUMMARY
+
+      # -----------------------------------------------------------------------
+      # On pull requests, post a comment summarising the outcome so reviewers
+      # don't have to open the Actions tab to check for visual regressions.
+      - name: Post PR comment
+        if: github.event_name == 'pull_request' && always()
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const outcome = '${{ steps.run-tests.outcome }}';
+            const sha = '${{ github.sha }}'.slice(0, 7);
+            const runUrl = `${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}`;
+
+            const icon   = outcome === 'success' ? '✅' : '❌';
+            const status = outcome === 'success'
+              ? 'No visual regressions detected.'
+              : 'Visual regressions detected (or new baselines need to be committed). Review the diff artifacts in the Actions run.';
+
+            const body = [
+              `## ${icon} Avalonia Visual Tests — \`${sha}\``,
+              '',
+              status,
+              '',
+              `**Artifacts:** [Screenshots & diffs](${runUrl})`,
+              '',
+              outcome !== 'success'
+                ? '_To accept intentional UI changes, trigger the **Avalonia Launcher Visual Tests** workflow manually with **Update baselines** enabled._'
+                : '',
+            ].join('\n');
+
+            // Find and update an existing bot comment, or create a new one.
+            const { data: comments } = await github.rest.issues.listComments({
+              owner: context.repo.owner,
+              repo:  context.repo.repo,
+              issue_number: context.issue.number,
+            });
+
+            const marker   = '## ✅ Avalonia Visual Tests';
+            const markerFail = '## ❌ Avalonia Visual Tests';
+            const existing = comments.find(c =>
+              c.user.type === 'Bot' &&
+              (c.body.includes('## ✅ Avalonia Visual Tests') || c.body.includes('## ❌ Avalonia Visual Tests'))
+            );
+
+            if (existing) {
+              await github.rest.issues.updateComment({
+                owner:      context.repo.owner,
+                repo:       context.repo.repo,
+                comment_id: existing.id,
+                body,
+              });
+            } else {
+              await github.rest.issues.createComment({
+                owner:        context.repo.owner,
+                repo:         context.repo.repo,
+                issue_number: context.issue.number,
+                body,
+              });
+            }
+
+      # -----------------------------------------------------------------------
+      # Update baselines: copy screenshots → Baselines/ and commit.
+      # Only runs when triggered via workflow_dispatch with update_baselines=true.
+      - name: Update baselines
+        if: inputs.update_baselines == true
+        shell: bash
+        run: |
+          BASELINES_DIR="LANCommander.Launcher.Avalonia.Tests/Baselines"
+          SCREENSHOTS_DIR="${{ env.VISUAL_SCREENSHOTS_DIR }}"
+
+          if [ ! -d "$SCREENSHOTS_DIR" ] || [ -z "$(ls -A "$SCREENSHOTS_DIR")" ]; then
+            echo "No screenshots found at $SCREENSHOTS_DIR — nothing to update."
+            exit 1
+          fi
+
+          mkdir -p "$BASELINES_DIR"
+          cp "$SCREENSHOTS_DIR"/*.png "$BASELINES_DIR/"
+          echo "Copied screenshots:"
+          ls "$BASELINES_DIR"
+
+          git config user.name  "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+          git add "$BASELINES_DIR"
+
+          if git diff --staged --quiet; then
+            echo "Baselines unchanged — nothing to commit."
+          else
+            git commit -m "chore: update Avalonia visual test baselines [skip ci]
+
+            Updated by workflow run ${{ github.run_id }} on branch ${{ github.ref_name }}."
+            git push
+            echo "Baselines committed and pushed."
+          fi
+
+      # -----------------------------------------------------------------------
+      # Re-raise test failure AFTER artifacts have been uploaded and comments posted.
+      - name: Fail on test regression
+        if: steps.run-tests.outcome == 'failure' && inputs.update_baselines != true
+        run: |
+          echo "Visual tests failed. See artifacts and step summary for details."
+          exit 1
diff --git a/.github/workflows/LANCommander.SDK.Tests.yml b/.github/workflows/LANCommander.SDK.Tests.yml
new file mode 100644
index 00000000..0d047a40
--- /dev/null
+++ b/.github/workflows/LANCommander.SDK.Tests.yml
@@ -0,0 +1,53 @@
+name: LANCommander SDK Tests
+
+on:
+    push:
+        branches:
+            - main
+        paths:
+            - 'LANCommander.SDK/**'
+            - 'LANCommander.SDK.Tests/**'
+            - 'LANCommander.Steam/**'
+    pull_request:
+        paths:
+            - 'LANCommander.SDK/**'
+            - 'LANCommander.SDK.Tests/**'
+            - 'LANCommander.Steam/**'
+    workflow_dispatch:
+
+jobs:
+    test:
+        name: Run SDK Tests
+        runs-on: ubuntu-latest
+
+        steps:
+            - name: Check out code
+              uses: actions/checkout@v4
+
+            - name: Setup .NET
+              uses: actions/setup-dotnet@v4
+              with:
+                  dotnet-version: '10.0.x'
+
+            - name: Restore dependencies
+              run: dotnet restore LANCommander.SDK.Tests/LANCommander.SDK.Tests.csproj
+
+            - name: Build
+              run: dotnet build --no-restore --configuration Release LANCommander.SDK.Tests/LANCommander.SDK.Tests.csproj
+
+            - name: Run tests
+              run: >
+                  dotnet test
+                  --no-build
+                  --configuration Release
+                  --verbosity normal
+                  --logger "trx;LogFileName=sdk-tests.trx"
+                  LANCommander.SDK.Tests/LANCommander.SDK.Tests.csproj
+
+            - name: Upload test results
+              if: always()
+              uses: actions/upload-artifact@v4
+              with:
+                  name: sdk-test-results
+                  path: '**/*.trx'
+                  retention-days: 30
diff --git a/LANCommander.SDK.Tests/Extensions/EnumExtensionsTests.cs b/LANCommander.SDK.Tests/Extensions/EnumExtensionsTests.cs
new file mode 100644
index 00000000..abcf6844
--- /dev/null
+++ b/LANCommander.SDK.Tests/Extensions/EnumExtensionsTests.cs
@@ -0,0 +1,68 @@
+using LANCommander.SDK.Enums;
+using LANCommander.SDK.Extensions;
+
+namespace LANCommander.SDK.Tests.Extensions;
+
+public class EnumExtensionsTests
+{
+    private enum Color { Red, Green, Blue }
+
+    // ── ValueIsIn ──────────────────────────────────────────────────────────────
+
+    [Fact]
+    public void ValueIsIn_WhenValueIsInList_ReturnsTrue()
+    {
+        var result = Color.Green.ValueIsIn(Color.Red, Color.Green, Color.Blue);
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public void ValueIsIn_WhenValueIsNotInList_ReturnsFalse()
+    {
+        var result = Color.Blue.ValueIsIn(Color.Red, Color.Green);
+
+        Assert.False(result);
+    }
+
+    [Fact]
+    public void ValueIsIn_WithEmptyList_ReturnsFalse()
+    {
+        var result = Color.Red.ValueIsIn();
+
+        Assert.False(result);
+    }
+
+    [Fact]
+    public void ValueIsIn_WithSingleMatchingValue_ReturnsTrue()
+    {
+        var result = Color.Red.ValueIsIn(Color.Red);
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public void ValueIsIn_WithSortDirectionEnum_WorksCorrectly()
+    {
+        var result = SortDirection.Descending.ValueIsIn(SortDirection.Ascending, SortDirection.Descending);
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public void ValueIsIn_WorksWithNonEnumTypes()
+    {
+        // The extension is generic — not restricted to enums.
+        var result = "hello".ValueIsIn("world", "hello", "foo");
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public void ValueIsIn_WorksWithIntegers()
+    {
+        var result = 42.ValueIsIn(1, 2, 42, 100);
+
+        Assert.True(result);
+    }
+}
diff --git a/LANCommander.SDK.Tests/Extensions/GuidExtensionsTests.cs b/LANCommander.SDK.Tests/Extensions/GuidExtensionsTests.cs
new file mode 100644
index 00000000..7e3e9389
--- /dev/null
+++ b/LANCommander.SDK.Tests/Extensions/GuidExtensionsTests.cs
@@ -0,0 +1,41 @@
+using LANCommander.SDK.Extensions;
+
+namespace LANCommander.SDK.Tests.Extensions;
+
+public class GuidExtensionsTests
+{
+    // ── IsNullOrEmpty ──────────────────────────────────────────────────────────
+
+    [Fact]
+    public void IsNullOrEmpty_WithEmptyGuid_ReturnsTrue()
+    {
+        var result = Guid.Empty.IsNullOrEmpty();
+
+        Assert.True(result);
+    }
+
+    [Fact]
+    public void IsNullOrEmpty_WithDefaultGuid_ReturnsTrue()
+    {
+        // default(Guid) == Guid.Empty
+        var guid = default(Guid);
+
+        Assert.True(guid.IsNullOrEmpty());
+    }
+
+    [Fact]
+    public void IsNullOrEmpty_WithNewGuid_ReturnsFalse()
+    {
+        var result = Guid.NewGuid().IsNullOrEmpty();
+
+        Assert.False(result);
+    }
+
+    [Fact]
+    public void IsNullOrEmpty_WithKnownNonEmptyGuid_ReturnsFalse()
+    {
+        var guid = new Guid("12345678-1234-1234-1234-123456789012");
+
+        Assert.False(guid.IsNullOrEmpty());
+    }
+}
diff --git a/LANCommander.SDK.Tests/Extensions/IEnumerableExtensionsTests.cs b/LANCommander.SDK.Tests/Extensions/IEnumerableExtensionsTests.cs
new file mode 100644
index 00000000..2bf3e78a
--- /dev/null
+++ b/LANCommander.SDK.Tests/Extensions/IEnumerableExtensionsTests.cs
@@ -0,0 +1,197 @@
+using LANCommander.SDK.Enums;
+using LANCommander.SDK.Extensions;
+
+namespace LANCommander.SDK.Tests.Extensions;
+
+public class IEnumerableExtensionsTests
+{
+    // ── OrderByTitle ───────────────────────────────────────────────────────────
+
+    [Fact]
+    public void OrderByTitle_StripsLeadingThe_ForSortKey()
+    {
+        var titles = new[] { "Zelda", "The Witcher", "Baldur's Gate" };
+
+        var result = titles.OrderByTitle(t => t).Select(t => t).ToList();
+
+        // "The Witcher" sorts as "Witcher", coming after "Zelda" is wrong —
+        // actual order: Baldur's Gate, The Witcher, Zelda
+        Assert.Equal("Baldur's Gate", result[0]);
+        Assert.Equal("The Witcher",   result[1]);
+        Assert.Equal("Zelda",         result[2]);
+    }
+
+    [Fact]
+    public void OrderByTitle_StripsLeadingA_ForSortKey()
+    {
+        var titles = new[] { "Call of Duty", "A Plague Tale", "Doom" };
+
+        var result = titles.OrderByTitle(t => t).ToList();
+
+        // "A Plague Tale" sorts as "Plague Tale"
+        Assert.Equal("Call of Duty", result[0]);
+        Assert.Equal("Doom",         result[1]);
+        Assert.Equal("A Plague Tale", result[2]);
+    }
+
+    [Fact]
+    public void OrderByTitle_StripsLeadingAn_ForSortKey()
+    {
+        var titles = new[] { "Batman", "An Elder Tale", "Civilization" };
+
+        var result = titles.OrderByTitle(t => t).ToList();
+
+        // "An Elder Tale" sorts as "Elder Tale"
+        Assert.Equal("Batman",        result[0]);
+        Assert.Equal("Civilization",  result[1]);
+        Assert.Equal("An Elder Tale", result[2]);
+    }
+
+    [Fact]
+    public void OrderByTitle_ArticleStrippingIsCaseInsensitive()
+    {
+        var titles = new[] { "Zelda", "the Witcher", "Baldur's Gate" };
+
+        var result = titles.OrderByTitle(t => t).ToList();
+
+        Assert.Equal("Baldur's Gate", result[0]);
+        Assert.Equal("the Witcher",   result[1]);
+        Assert.Equal("Zelda",         result[2]);
+    }
+
+    [Fact]
+    public void OrderByTitle_WordStartingWithArticleButNoTrailingSpace_IsNotStripped()
+    {
+        // "Another World" starts with "An" but "Another" ≠ "an "
+        // "There" starts with "The" but "There" ≠ "the "
+        var titles = new[] { "Another World", "There Will Be Blood", "Abzu" };
+
+        var result = titles.OrderByTitle(t => t).ToList();
+
+        Assert.Equal("Abzu",                result[0]);
+        Assert.Equal("Another World",       result[1]);
+        Assert.Equal("There Will Be Blood", result[2]);
+    }
+
+    [Fact]
+    public void OrderByTitle_Descending_ReversesOrder()
+    {
+        var titles = new[] { "The Witcher", "Baldur's Gate", "Zelda" };
+
+        var result = titles.OrderByTitle(t => t, SortDirection.Descending).ToList();
+
+        Assert.Equal("Zelda",         result[0]);
+        Assert.Equal("The Witcher",   result[1]);
+        Assert.Equal("Baldur's Gate", result[2]);
+    }
+
+    [Fact]
+    public void OrderByTitle_WorksWithObjectKeySelector()
+    {
+        var games = new[]
+        {
+            new { Id = 1, Title = "The Last of Us" },
+            new { Id = 2, Title = "Among Us" },
+            new { Id = 3, Title = "Hades" },
+        };
+
+        var result = games.OrderByTitle(g => g.Title).ToList();
+
+        // "The Last of Us" → "Last of Us", "Among Us" → "Among Us", "Hades" → "Hades"
+        Assert.Equal(2, result[0].Id); // Among Us
+        Assert.Equal(3, result[1].Id); // Hades
+        Assert.Equal(1, result[2].Id); // The Last of Us
+    }
+
+    // ── OrderBy (SortDirection overload) ──────────────────────────────────────
+
+    [Fact]
+    public void OrderBy_Ascending_SortsSmallestFirst()
+    {
+        var numbers = new[] { 3, 1, 4, 1, 5, 9, 2 };
+
+        var result = numbers.OrderBy(n => n, SortDirection.Ascending).ToList();
+
+        Assert.Equal(new[] { 1, 1, 2, 3, 4, 5, 9 }, result);
+    }
+
+    [Fact]
+    public void OrderBy_Descending_SortsLargestFirst()
+    {
+        var numbers = new[] { 3, 1, 4, 1, 5, 9, 2 };
+
+        var result = numbers.OrderBy(n => n, SortDirection.Descending).ToList();
+
+        Assert.Equal(new[] { 9, 5, 4, 3, 2, 1, 1 }, result);
+    }
+
+    [Fact]
+    public void OrderBy_OnStrings_Ascending()
+    {
+        var words = new[] { "banana", "apple", "cherry" };
+
+        var result = words.OrderBy(w => w, SortDirection.Ascending).ToList();
+
+        Assert.Equal(new[] { "apple", "banana", "cherry" }, result);
+    }
+
+    // ── HasAny (no predicate) ──────────────────────────────────────────────────
+
+    [Fact]
+    public void HasAny_WithNonEmptyCollection_ReturnsTrue()
+    {
+        var list = new[] { 1, 2, 3 };
+
+        Assert.True(list.HasAny());
+    }
+
+    [Fact]
+    public void HasAny_WithEmptyCollection_ReturnsFalse()
+    {
+        var list = Array.Empty<int>();
+
+        Assert.False(list.HasAny());
+    }
+
+    [Fact]
+    public void HasAny_WithNullCollection_ReturnsFalse()
+    {
+        IEnumerable<int>? list = null;
+
+        Assert.False(list.HasAny());
+    }
+
+    // ── HasAny (with predicate) ────────────────────────────────────────────────
+
+    [Fact]
+    public void HasAny_WithPredicate_WhenMatchExists_ReturnsTrue()
+    {
+        var list = new[] { 1, 2, 3, 4, 5 };
+
+        Assert.True(list.HasAny(n => n > 4));
+    }
+
+    [Fact]
+    public void HasAny_WithPredicate_WhenNoMatch_ReturnsFalse()
+    {
+        var list = new[] { 1, 2, 3 };
+
+        Assert.False(list.HasAny(n => n > 10));
+    }
+
+    [Fact]
+    public void HasAny_WithPredicate_OnNullCollection_ReturnsFalse()
+    {
+        IEnumerable<int>? list = null;
+
+        Assert.False(list.HasAny(n => n > 0));
+    }
+
+    [Fact]
+    public void HasAny_WithPredicate_OnEmptyCollection_ReturnsFalse()
+    {
+        var list = Array.Empty<int>();
+
+        Assert.False(list.HasAny(n => n > 0));
+    }
+}
diff --git a/LANCommander.SDK.Tests/Extensions/ListExtensionsTests.cs b/LANCommander.SDK.Tests/Extensions/ListExtensionsTests.cs
new file mode 100644
index 00000000..ef6923a9
--- /dev/null
+++ b/LANCommander.SDK.Tests/Extensions/ListExtensionsTests.cs
@@ -0,0 +1,154 @@
+using LANCommander.SDK.Extensions;
+
+namespace LANCommander.SDK.Tests.Extensions;
+
+public class ListExtensionsTests
+{
+    // ── RemoveRange ────────────────────────────────────────────────────────────
+
+    [Fact]
+    public void RemoveRange_RemovesAllSpecifiedItems()
+    {
+        var list = new List<int> { 1, 2, 3, 4, 5 };
+
+        list.RemoveRange(new[] { 2, 4 });
+
+        Assert.Equal(new[] { 1, 3, 5 }, list);
+    }
+
+    [Fact]
+    public void RemoveRange_ItemsNotInCollection_AreIgnored()
+    {
+        var list = new List<int> { 1, 2, 3 };
+
+        list.RemoveRange(new[] { 99, 100 });
+
+        Assert.Equal(new[] { 1, 2, 3 }, list);
+    }
+
+    [Fact]
+    public void RemoveRange_WithNullItemsToRemove_DoesNotThrow()
+    {
+        var list = new List<int> { 1, 2, 3 };
+
+        list.RemoveRange(null);
+
+        Assert.Equal(new[] { 1, 2, 3 }, list);
+    }
+
+    [Fact]
+    public void RemoveRange_WithEmptyItemsToRemove_LeavesCollectionUnchanged()
+    {
+        var list = new List<int> { 1, 2, 3 };
+
+        list.RemoveRange(Array.Empty<int>());
+
+        Assert.Equal(new[] { 1, 2, 3 }, list);
+    }
+
+    [Fact]
+    public void RemoveRange_RemovesAllItems_WhenAllSpecified()
+    {
+        var list = new List<string> { "a", "b", "c" };
+
+        list.RemoveRange(new[] { "a", "b", "c" });
+
+        Assert.Empty(list);
+    }
+
+    [Fact]
+    public void RemoveRange_OnlyRemovesFirstOccurrence_ForDuplicates()
+    {
+        // List<T>.Remove removes only the first matching element.
+        var list = new List<int> { 1, 2, 2, 3 };
+
+        list.RemoveRange(new[] { 2 });
+
+        Assert.Equal(new[] { 1, 2, 3 }, list);
+    }
+
+    [Fact]
+    public void RemoveRange_WorksWithReferenceTypes()
+    {
+        var a = new object();
+        var b = new object();
+        var c = new object();
+        var list = new List<object> { a, b, c };
+
+        list.RemoveRange(new[] { b });
+
+        Assert.Equal(new[] { a, c }, list);
+    }
+
+    // ── RemoveAll ──────────────────────────────────────────────────────────────
+
+    [Fact]
+    public void RemoveAll_RemovesItemsMatchingPredicate()
+    {
+        var list = new List<int> { 1, 2, 3, 4, 5 };
+
+        list.RemoveAll(n => n % 2 == 0);
+
+        Assert.Equal(new[] { 1, 3, 5 }, list);
+    }
+
+    [Fact]
+    public void RemoveAll_KeepsItemsNotMatchingPredicate()
+    {
+        var list = new List<int> { 1, 2, 3, 4, 5 };
+
+        list.RemoveAll(n => n > 10);
+
+        Assert.Equal(new[] { 1, 2, 3, 4, 5 }, list);
+    }
+
+    [Fact]
+    public void RemoveAll_WithNullPredicate_ThrowsArgumentNullException()
+    {
+        var list = new List<int> { 1, 2, 3 };
+
+        Assert.Throws<ArgumentNullException>(() => list.RemoveAll(null!));
+    }
+
+    [Fact]
+    public void RemoveAll_WithEmptyCollection_DoesNotThrow()
+    {
+        var list = new List<int>();
+
+        var ex = Record.Exception(() => list.RemoveAll(n => n > 0));
+
+        Assert.Null(ex);
+        Assert.Empty(list);
+    }
+
+    [Fact]
+    public void RemoveAll_WithAllMatchingPredicate_EmptiesCollection()
+    {
+        var list = new List<int> { 1, 2, 3 };
+
+        list.RemoveAll(_ => true);
+
+        Assert.Empty(list);
+    }
+
+    [Fact]
+    public void RemoveAll_RemovesItemsCorrectlyWhenIteratingBackwards()
+    {
+        // Verify that removing while iterating backwards doesn't skip or double-remove.
+        var list = new List<int> { 1, 2, 3, 4, 5, 6 };
+
+        list.RemoveAll(n => n % 3 == 0);
+
+        Assert.Equal(new[] { 1, 2, 4, 5 }, list);
+    }
+
+    [Fact]
+    public void RemoveAll_WorksWithStrings()
+    {
+        var list = new List<string> { "alpha", "beta", "gamma", "delta" };
+
+        list.RemoveAll(s => s.StartsWith("b") || s.StartsWith("d"));
+
+        Assert.Equal(new[] { "alpha", "gamma" }, list);
+    }
+}
diff --git a/LANCommander.SDK.Tests/Extensions/StreamExtensionsTests.cs b/LANCommander.SDK.Tests/Extensions/StreamExtensionsTests.cs
new file mode 100644
index 00000000..61e27d4b
--- /dev/null
+++ b/LANCommander.SDK.Tests/Extensions/StreamExtensionsTests.cs
@@ -0,0 +1,125 @@
+using LANCommander.SDK.Extensions;
+
+namespace LANCommander.SDK.Tests.Extensions;
+
+public class StreamExtensionsTests
+{
+    private static MemoryStream MakeStream(int sizeBytes, byte fill = 0xAB)
+    {
+        var data = new byte[sizeBytes];
+        Array.Fill(data, fill);
+        return new MemoryStream(data);
+    }
+
+    // ── Content correctness ───────────────────────────────────────────────────
+
+    [Fact]
+    public async Task CopyToAsync_CopiesAllBytesToDestination()
+    {
+        var source      = MakeStream(256, fill: 0x42);
+        var destination = new MemoryStream();
+
+        await source.CopyToAsync(destination);
+
+        destination.Position = 0;
+        var result = destination.ToArray();
+        Assert.Equal(256, result.Length);
+        Assert.All(result, b => Assert.Equal(0x42, b));
+    }
+
+    [Fact]
+    public async Task CopyToAsync_EmptySource_ProducesEmptyDestination()
+    {
+        var source      = new MemoryStream();
+        var destination = new MemoryStream();
+
+        await source.CopyToAsync(destination);
+
+        Assert.Equal(0, destination.Length);
+    }
+
+    [Fact]
+    public async Task CopyToAsync_LargerThanBuffer_CopiesAllBytes()
+    {
+        // Default buffer is 1 MB; use 3 MB to force multiple reads.
+        const int size  = 3 * 1024 * 1024;
+        var source      = MakeStream(size, fill: 0x77);
+        var destination = new MemoryStream();
+
+        await source.CopyToAsync(destination);
+
+        Assert.Equal(size, destination.Length);
+    }
+
+    // ── Progress callback ──────────────────────────────────────────────────────
+
+    [Fact]
+    public async Task CopyToAsync_FinalProgressCallback_IsAlwaysInvoked()
+    {
+        var source      = MakeStream(128);
+        var destination = new MemoryStream();
+
+        long lastTransferred = -1;
+        long lastTotal       = -1;
+
+        await source.CopyToAsync(destination, (transferred, total) =>
+        {
+            lastTransferred = transferred;
+            lastTotal       = total;
+        });
+
+        Assert.Equal(128, lastTransferred);
+        Assert.Equal(128, lastTotal);
+    }
+
+    [Fact]
+    public async Task CopyToAsync_ProgressCallback_IsInvokedAtConfiguredInterval()
+    {
+        // Use a stream larger than the report interval to trigger mid-copy callbacks.
+        const int reportInterval = 64 * 1024;          // 64 KB
+        const int streamSize     = 4 * reportInterval; // 256 KB — forces several interval hits
+
+        var source      = MakeStream(streamSize);
+        var destination = new MemoryStream();
+
+        var callbackValues = new List<long>();
+
+        await source.CopyToAsync(
+            destination,
+            progressCallback:    (transferred, _) => callbackValues.Add(transferred),
+            bufferSize:          reportInterval,     // each read == one interval
+            reportIntervalBytes: reportInterval);
+
+        // At minimum the final callback fires; with buffer == interval every read triggers one.
+        Assert.NotEmpty(callbackValues);
+        // Last reported value is the total bytes.
+        Assert.Equal(streamSize, callbackValues.Last());
+    }
+
+    [Fact]
+    public async Task CopyToAsync_WithNullProgressCallback_DoesNotThrow()
+    {
+        var source      = MakeStream(256);
+        var destination = new MemoryStream();
+
+        var ex = await Record.ExceptionAsync(() =>
+            source.CopyToAsync(destination, progressCallback: null));
+
+        Assert.Null(ex);
+    }
+
+    // ── Cancellation ──────────────────────────────────────────────────────────
+
+    [Fact]
+    public async Task CopyToAsync_WithAlreadyCancelledToken_ThrowsOperationCanceledException()
+    {
+        var source      = MakeStream(1024 * 1024); // large enough to not finish before cancellation
+        var destination = new MemoryStream();
+
+        using var cts = new CancellationTokenSource();
+        cts.Cancel();
+
+        await Assert.ThrowsAnyAsync<OperationCanceledException>(() =>
+            source.CopyToAsync(destination, cancellationToken: cts.Token));
+    }
+}
diff --git a/LANCommander.SDK.Tests/Extensions/StringExtensionsTests.cs b/LANCommander.SDK.Tests/Extensions/StringExtensionsTests.cs
new file mode 100644
index 00000000..499924db
--- /dev/null
+++ b/LANCommander.SDK.Tests/Extensions/StringExtensionsTests.cs
@@ -0,0 +1,117 @@
+using LANCommander.SDK.Extensions;
+
+namespace LANCommander.SDK.Tests.Extensions;
+
+public class StringExtensionsTests
+{
+    // ── SanitizeFilename ───────────────────────────────────────────────────────
+
+    [Theory]
+    [InlineData("Half-Life 2: Episode One",  "Half-Life 2 - Episode One")]
+    [InlineData("Game: The Sequel",          "Game - The Sequel")]
+    [InlineData("Foo: Bar",                  "Foo - Bar")]
+    public void SanitizeFilename_ColonSpacePattern_IsReplacedWithDash(string input, string expected)
+    {
+        Assert.Equal(expected, input.SanitizeFilename());
+    }
+
+    [Fact]
+    public void SanitizeFilename_ColonWithNoSpaceAfter_IsNotChanged()
+    {
+        // Only "word: word" (colon-space) triggers the replacement, not bare colons.
+        // On Linux, ':' is not an invalid filename character so it is left as-is.
+        var result = "http://example".SanitizeFilename();
+
+        // No "word: word" match → colon stays; '/' is invalid on all platforms.
+        Assert.DoesNotContain("/", result);
+    }
+
+    [Fact]
+    public void SanitizeFilename_TrailingDot_IsRemoved()
+    {
+        var result = "GameTitle.".SanitizeFilename();
+
+        Assert.Equal("GameTitle", result);
+    }
+
+    [Fact]
+    public void SanitizeFilename_NonTrailingDot_IsPreserved()
+    {
+        var result = "game.exe".SanitizeFilename();
+
+        Assert.Equal("game.exe", result);
+    }
+
+    [Fact]
+    public void SanitizeFilename_MultipleDots_OnlyLastRemoved()
+    {
+        var result = "game...".SanitizeFilename();
+
+        Assert.Equal("game..", result);
+    }
+
+    [Fact]
+    public void SanitizeFilename_ForwardSlash_IsRemoved()
+    {
+        // '/' is in Path.GetInvalidFileNameChars() on all platforms.
+        var result = "foo/bar".SanitizeFilename();
+
+        Assert.Equal("foobar", result);
+    }
+
+    [Fact]
+    public void SanitizeFilename_ForwardSlash_ReplacedWithCustomString()
+    {
+        var result = "foo/bar".SanitizeFilename("_");
+
+        Assert.Equal("foo_bar", result);
+    }
+
+    [Fact]
+    public void SanitizeFilename_NoInvalidChars_ReturnsUnchanged()
+    {
+        var result = "NormalTitle".SanitizeFilename();
+
+        Assert.Equal("NormalTitle", result);
+    }
+
+    [Fact]
+    public void SanitizeFilename_ColonAndTrailingDot_BothHandled()
+    {
+        var result = "Game: Edition.".SanitizeFilename();
+
+        Assert.Equal("Game - Edition", result);
+    }
+
+    // ── FastReverse ────────────────────────────────────────────────────────────
+
+    [Theory]
+    [InlineData("hello",   "olleh")]
+    [InlineData("abcde",   "edcba")]
+    [InlineData("12345",   "54321")]
+    [InlineData("a",       "a")]
+    public void FastReverse_ReversesString(string input, string expected)
+    {
+        Assert.Equal(expected, input.FastReverse());
+    }
+
+    [Fact]
+    public void FastReverse_EmptyString_ReturnsEmpty()
+    {
+        Assert.Equal("", "".FastReverse());
+    }
+
+    [Fact]
+    public void FastReverse_Palindrome_ReturnsSameValue()
+    {
+        Assert.Equal("racecar", "racecar".FastReverse());
+    }
+
+    [Fact]
+    public void FastReverse_TwiceProducesOriginal()
+    {
+        const string original = "LANCommander";
+
+        Assert.Equal(original, original.FastReverse().FastReverse());
+    }
+}
diff --git a/LANCommander.SDK.Tests/Extensions/UriExtensionsTests.cs b/LANCommander.SDK.Tests/Extensions/UriExtensionsTests.cs
new file mode 100644
index 00000000..a5241f42
--- /dev/null
+++ b/LANCommander.SDK.Tests/Extensions/UriExtensionsTests.cs
@@ -0,0 +1,198 @@
+using LANCommander.SDK.Extensions;
+using SdkUriExtensions = LANCommander.SDK.Extensions.UriExtensions;
+
+namespace LANCommander.SDK.Tests.Extensions;
+
+public class UriExtensionsTests
+{
+    // ── Join ──────────────────────────────────────────────────────────────────
+
+    [Fact]
+    public void Join_AppendsSingleSegment()
+    {
+        var base_ = new Uri("http://example.com");
+
+        var result = base_.Join("api");
+
+        Assert.Equal("http://example.com/api", result.ToString());
+    }
+
+    [Fact]
+    public void Join_AppendsMultipleSegments()
+    {
+        var base_ = new Uri("http://example.com");
+
+        var result = base_.Join("api", "v1", "games");
+
+        Assert.Equal("http://example.com/api/v1/games", result.ToString());
+    }
+
+    [Fact]
+    public void Join_StripsTrailingSlashFromBase()
+    {
+        var base_ = new Uri("http://example.com/");
+
+        var result = base_.Join("api");
+
+        Assert.Equal("http://example.com/api", result.ToString());
+    }
+
+    [Fact]
+    public void Join_StripsLeadingSlashFromSegment()
+    {
+        var base_ = new Uri("http://example.com");
+
+        var result = base_.Join("/api");
+
+        Assert.Equal("http://example.com/api", result.ToString());
+    }
+
+    [Fact]
+    public void Join_StripsLeadingAndTrailingSlashesFromSegments()
+    {
+        var base_ = new Uri("http://example.com/");
+
+        var result = base_.Join("/api/", "/v1/");
+
+        Assert.Equal("http://example.com/api/v1", result.ToString());
+    }
+
+    [Fact]
+    public void Join_WithBaseContainingPath_AppendsCorrectly()
+    {
+        var base_ = new Uri("http://example.com/root");
+
+        var result = base_.Join("sub");
+
+        Assert.Equal("http://example.com/root/sub", result.ToString());
+    }
+
+    // ── CreateUri ─────────────────────────────────────────────────────────────
+
+    [Fact]
+    public void CreateUri_WithFullHttpUri_ReturnsSameUri()
+    {
+        var result = SdkUriExtensions.CreateUri("http://example.com");
+
+        Assert.Equal("http://example.com/", result.ToString());
+    }
+
+    [Fact]
+    public void CreateUri_WithFullHttpsUri_ReturnsSameUri()
+    {
+        var result = SdkUriExtensions.CreateUri("https://example.com");
+
+        Assert.Equal("https://example.com/", result.ToString());
+    }
+
+    [Fact]
+    public void CreateUri_WithNoScheme_PrependsHttp()
+    {
+        var result = SdkUriExtensions.CreateUri("example.com");
+
+        Assert.Equal(Uri.UriSchemeHttp, result.Scheme);
+        Assert.Equal("example.com", result.Host);
+    }
+
+    [Fact]
+    public void CreateUri_WithNullInput_ThrowsArgumentException()
+    {
+        Assert.Throws<ArgumentException>(() => SdkUriExtensions.CreateUri(null));
+    }
+
+    [Fact]
+    public void CreateUri_WithEmptyInput_ThrowsArgumentException()
+    {
+        Assert.Throws<ArgumentException>(() => SdkUriExtensions.CreateUri(""));
+    }
+
+    [Fact]
+    public void CreateUri_WithWhitespaceInput_ThrowsArgumentException()
+    {
+        Assert.Throws<ArgumentException>(() => SdkUriExtensions.CreateUri("   "));
+    }
+
+    [Fact]
+    public void CreateUri_WithUriContainingPort_PreservesPort()
+    {
+        var result = SdkUriExtensions.CreateUri("http://localhost:1337");
+
+        Assert.Equal(1337, result.Port);
+    }
+
+    [Fact]
+    public void CreateUri_WithIpAddress_Works()
+    {
+        var result = SdkUriExtensions.CreateUri("192.168.1.1");
+
+        Assert.Equal(Uri.UriSchemeHttp, result.Scheme);
+        Assert.Equal("192.168.1.1", result.Host);
+    }
+
+    // ── TryCreateUri ──────────────────────────────────────────────────────────
+
+    [Fact]
+    public void TryCreateUri_WithValidUri_ReturnsTrueAndSetsResult()
+    {
+        var success = SdkUriExtensions.TryCreateUri("http://example.com", out var result);
+
+        Assert.True(success);
+        Assert.NotNull(result);
+        Assert.Equal("http://example.com/", result.ToString());
+    }
+
+    [Fact]
+    public void TryCreateUri_WithNoScheme_PrependsHttpAndReturnsTrue()
+    {
+        var success = SdkUriExtensions.TryCreateUri("example.com", out var result);
+
+        Assert.True(success);
+        Assert.NotNull(result);
+        Assert.Equal(Uri.UriSchemeHttp, result.Scheme);
+    }
+
+    [Fact]
+    public void TryCreateUri_WithNullInput_ReturnsFalse()
+    {
+        var success = SdkUriExtensions.TryCreateUri(null, out var result);
+
+        Assert.False(success);
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public void TryCreateUri_WithEmptyInput_ReturnsFalse()
+    {
+        var success = SdkUriExtensions.TryCreateUri("", out var result);
+
+        Assert.False(success);
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public void TryCreateUri_WithWhitespace_ReturnsFalse()
+    {
+        var success = SdkUriExtensions.TryCreateUri("   ", out var result);
+
+        Assert.False(success);
+        Assert.Null(result);
+    }
+
+    [Fact]
+    public void TryCreateUri_WithHttpsScheme_PreservesScheme()
+    {
+        var success = SdkUriExtensions.TryCreateUri("https://secure.example.com", out var result);
+
+        Assert.True(success);
+        Assert.Equal(Uri.UriSchemeHttps, result!.Scheme);
+    }
+
+    [Fact]
+    public void TryCreateUri_WithPortNumber_PreservesPort()
+    {
+        var success = SdkUriExtensions.TryCreateUri("http://localhost:8080", out var result);
+
+        Assert.True(success);
+        Assert.Equal(8080, result!.Port);
+    }
+}
diff --git a/LANCommander.SDK.Tests/Fixtures/FakeGameFixture.cs b/LANCommander.SDK.Tests/Fixtures/FakeGameFixture.cs
new file mode 100644
index 00000000..895cfc02
--- /dev/null
+++ b/LANCommander.SDK.Tests/Fixtures/FakeGameFixture.cs
@@ -0,0 +1,151 @@
+using LANCommander.SDK.Enums;
+using LANCommander.SDK.Helpers;
+using ManifestGame = LANCommander.SDK.Models.Manifest.Game;
+using ManifestKey = LANCommander.SDK.Models.Manifest.Key;
+using ManifestMedia = LANCommander.SDK.Models.Manifest.Media;
+using ManifestSavePath = LANCommander.SDK.Models.Manifest.SavePath;
+using ManifestScript = LANCommander.SDK.Models.Manifest.Script;
+
+namespace LANCommander.SDK.Tests.Fixtures;
+
+/// <summary>
+/// Builds a complete fake game installation on disk for integration testing.
+/// Creates save files, script stubs, and writes a full manifest covering
+/// saves, keys, scripts, and media — everything DownloadAsync / UploadAsync touches.
+/// </summary>
+public sealed class FakeGameFixture : IDisposable
+{
+    // ── Identity ──────────────────────────────────────────────────────────────
+
+    /// <summary>Stable ID for the fake game, used as the manifest key and sub-directory name.</summary>
+    public Guid GameId { get; } = Guid.NewGuid();
+
+    /// <summary>Root installation directory created by the fixture.</summary>
+    public string InstallDirectory { get; }
+
+    // ── Manifest ──────────────────────────────────────────────────────────────
+
+    /// <summary>Fully populated manifest written to <c>.lancommander/{GameId}/Manifest.yml</c>.</summary>
+    public ManifestGame Manifest { get; }
+
+    // ── Save paths ────────────────────────────────────────────────────────────
+
+    /// <summary>SavePath that covers the <c>saves/</c> sub-directory inside the install dir.</summary>
+    public ManifestSavePath SavesDirSavePath { get; }
+
+    /// <summary>SavePath that covers the single <c>config.cfg</c> file in the install dir root.</summary>
+    public ManifestSavePath ConfigFileSavePath { get; }
+
+    // ── Computed on-disk paths ────────────────────────────────────────────────
+
+    public string SavesDirectory    => Path.Combine(InstallDirectory, "saves");
+    public string SaveFileSlot1Path => Path.Combine(SavesDirectory, "slot1.sav");
+    public string SaveFileSlot2Path => Path.Combine(SavesDirectory, "slot2.sav");
+    public string ConfigFilePath    => Path.Combine(InstallDirectory, "config.cfg");
+
+    // ── Known file contents ───────────────────────────────────────────────────
+
+    public const string Slot1Content  = "SAVE_DATA_SLOT_1";
+    public const string Slot2Content  = "SAVE_DATA_SLOT_2";
+    public const string ConfigContent = "player_name=TestPlayer\ngraphics=high";
+
+    // ── Construction ──────────────────────────────────────────────────────────
+
+    public FakeGameFixture()
+    {
+        InstallDirectory = Path.Combine(Path.GetTempPath(), $"lc-fake-game-{GameId}");
+        Directory.CreateDirectory(InstallDirectory);
+
+        // ── Save files ────────────────────────────────────────────────────────
+
+        Directory.CreateDirectory(SavesDirectory);
+        File.WriteAllText(SaveFileSlot1Path, Slot1Content);
+        File.WriteAllText(SaveFileSlot2Path, Slot2Content);
+        File.WriteAllText(ConfigFilePath,    ConfigContent);
+
+        // ── Script stubs on disk ──────────────────────────────────────────────
+
+        WriteScriptFile(ScriptType.Install,    "Write-Host 'Installing'");
+        WriteScriptFile(ScriptType.Uninstall,  "Write-Host 'Uninstalling'");
+        WriteScriptFile(ScriptType.BeforeStart,"Write-Host 'Before start'");
+        WriteScriptFile(ScriptType.AfterStop,  "Write-Host 'After stop'");
+        WriteScriptFile(ScriptType.NameChange, "Write-Host \"Name change: $PlayerAlias\"");
+        WriteScriptFile(ScriptType.KeyChange,  "Write-Host \"Key change: $AllocatedKey\"");
+
+        // ── Save paths ────────────────────────────────────────────────────────
+
+        SavesDirSavePath = new ManifestSavePath
+        {
+            Id             = Guid.NewGuid(),
+            Type           = SavePathType.File,
+            Path           = "saves",
+            WorkingDirectory = "{InstallDir}",
+            IsRegex        = false
+        };
+
+        ConfigFileSavePath = new ManifestSavePath
+        {
+            Id             = Guid.NewGuid(),
+            Type           = SavePathType.File,
+            Path           = "config.cfg",
+            WorkingDirectory = "{InstallDir}",
+            IsRegex        = false
+        };
+
+        // ── Manifest ──────────────────────────────────────────────────────────
+
+        Manifest = new ManifestGame
+        {
+            Id               = GameId,
+            Title            = "Fake Test Game",
+            Version          = "1.0.0",
+            InstallDirectory = InstallDirectory,
+
+            Keys = new List<ManifestKey>
+            {
+                new() { Value = "FAKE-KEY-AAAA-1111" },
+                new() { Value = "FAKE-KEY-BBBB-2222" }
+            },
+
+            Scripts = new List<ManifestScript>
+            {
+                new() { Id = Guid.NewGuid(), Type = ScriptType.Install,    Name = "Install" },
+                new() { Id = Guid.NewGuid(), Type = ScriptType.Uninstall,  Name = "Uninstall" },
+                new() { Id = Guid.NewGuid(), Type = ScriptType.BeforeStart,Name = "BeforeStart" },
+                new() { Id = Guid.NewGuid(), Type = ScriptType.AfterStop,  Name = "AfterStop" },
+                new() { Id = Guid.NewGuid(), Type = ScriptType.NameChange, Name = "NameChange" },
+                new() { Id = Guid.NewGuid(), Type = ScriptType.KeyChange,  Name = "KeyChange" }
+            },
+
+            Media = new List<ManifestMedia>
+            {
+                new() { Id = Guid.NewGuid(), FileId = Guid.NewGuid(), Type = MediaType.Cover,      MimeType = "image/jpeg", Crc32 = "AABBCCDD" },
+                new() { Id = Guid.NewGuid(), FileId = Guid.NewGuid(), Type = MediaType.Icon,       MimeType = "image/png",  Crc32 = "EEFF0011" },
+                new() { Id = Guid.NewGuid(), FileId = Guid.NewGuid(), Type = MediaType.Background, MimeType = "image/jpeg", Crc32 = "22334455" }
+            },
+
+            SavePaths = new List<ManifestSavePath>
+            {
+                SavesDirSavePath,
+                ConfigFileSavePath
+            }
+        };
+
+        ManifestHelper.Write(Manifest, InstallDirectory);
+    }
+
+    // ── Helpers ───────────────────────────────────────────────────────────────
+
+    private void WriteScriptFile(ScriptType type, string contents)
+    {
+        var path = ScriptHelper.GetScriptFilePath(InstallDirectory, GameId, type);
+        Directory.CreateDirectory(Path.GetDirectoryName(path)!);
+        File.WriteAllText(path, contents);
+    }
+
+    public void Dispose()
+    {
+        if (Directory.Exists(InstallDirectory))
+            Directory.Delete(InstallDirectory, true);
+    }
+}
diff --git a/LANCommander.SDK.Tests/Helpers/RetryHelperTests.cs b/LANCommander.SDK.Tests/Helpers/RetryHelperTests.cs
deleted file mode 100644
index 830ad9f7..00000000
--- a/LANCommander.SDK.Tests/Helpers/RetryHelperTests.cs
+++ /dev/null
@@ -1,206 +0,0 @@
-using LANCommander.SDK.Helpers;
-
-namespace LANCommander.SDK.Tests.Helpers;
-
-public class RetryHelperTests
-{
-    // ── RetryOnException<T> ───────────────────────────────────────────────────
-
-    [Fact]
-    public void RetryOnException_WhenActionSucceedsImmediately_ReturnsResult()
-    {
-        var result = RetryHelper.RetryOnException(3, TimeSpan.Zero, -1, () => 42);
-
-        Assert.Equal(42, result);
-    }
-
-    [Fact]
-    public void RetryOnException_WhenActionSucceedsOnSecondAttempt_ReturnsResult()
-    {
-        int calls = 0;
-
-        var result = RetryHelper.RetryOnException(3, TimeSpan.Zero, -1, () =>
-        {
-            calls++;
-            if (calls < 2) throw new Exception("first attempt fails");
-            return 99;
-        });
-
-        Assert.Equal(99, result);
-        Assert.Equal(2, calls);
-    }
-
-    [Fact]
-    public void RetryOnException_WhenActionAlwaysFails_ReturnsDefault()
-    {
-        var result = RetryHelper.RetryOnException(3, TimeSpan.Zero, -1, () =>
-        {
-            throw new Exception("always fails");
-#pragma warning disable CS0162
-            return 0;
-#pragma warning restore CS0162
-        });
-
-        Assert.Equal(-1, result);
-    }
-
-    [Fact]
-    public void RetryOnException_WhenActionAlwaysFails_TriesMaxAttemptsTimes()
-    {
-        int calls = 0;
-
-        RetryHelper.RetryOnException(4, TimeSpan.Zero, -1, () =>
-        {
-            calls++;
-            throw new Exception("fail");
-#pragma warning disable CS0162
-            return 0;
-#pragma warning restore CS0162
-        });
-
-        Assert.Equal(4, calls);
-    }
-
-    [Fact]
-    public void RetryOnException_WithOneMaxAttempt_DoesNotRetry()
-    {
-        int calls = 0;
-
-        RetryHelper.RetryOnException(1, TimeSpan.Zero, -1, () =>
-        {
-            calls++;
-            throw new Exception("fail");
-#pragma warning disable CS0162
-            return 0;
-#pragma warning restore CS0162
-        });
-
-        Assert.Equal(1, calls);
-    }
-
-    // ── RetryOnException (void) ───────────────────────────────────────────────
-    // NOTE: The void overload has an infinite loop bug: on successful execution
-    // of action() there is no return or break, so the loop continues indefinitely.
-    // Success-path tests for this overload are skipped to avoid hanging.
-
-    [Fact(Skip = "RetryOnException void overload loops infinitely on success (missing return/break after action())")]
-    public void RetryOnException_Void_WhenActionSucceedsImmediately_CompletesOnce()
-    {
-        bool ran = false;
-        RetryHelper.RetryOnException(3, TimeSpan.Zero, () => { ran = true; });
-        Assert.True(ran);
-    }
-
-    [Fact]
-    public void RetryOnException_Void_WhenActionAlwaysFails_TriesMaxAttemptsTimes()
-    {
-        int calls = 0;
-
-        RetryHelper.RetryOnException(3, TimeSpan.Zero, () =>
-        {
-            calls++;
-            throw new Exception("fail");
-        });
-
-        Assert.Equal(3, calls);
-    }
-
-    [Fact]
-    public void RetryOnException_Void_WithOneMaxAttempt_DoesNotRetry()
-    {
-        int calls = 0;
-
-        RetryHelper.RetryOnException(1, TimeSpan.Zero, () =>
-        {
-            calls++;
-            throw new Exception("fail");
-        });
-
-        Assert.Equal(1, calls);
-    }
-
-    // ── RetryOnExceptionAsync<T> ──────────────────────────────────────────────
-
-    [Fact]
-    public async Task RetryOnExceptionAsync_WhenActionSucceedsImmediately_ReturnsResult()
-    {
-        var result = await RetryHelper.RetryOnExceptionAsync(3, TimeSpan.Zero, -1, () => Task.FromResult(42));
-
-        Assert.Equal(42, result);
-    }
-
-    [Fact]
-    public async Task RetryOnExceptionAsync_WhenActionSucceedsOnSecondAttempt_ReturnsResult()
-    {
-        int calls = 0;
-
-        var result = await RetryHelper.RetryOnExceptionAsync(3, TimeSpan.Zero, -1, () =>
-        {
-            calls++;
-            if (calls < 2) throw new Exception("first attempt fails");
-            return Task.FromResult(77);
-        });
-
-        Assert.Equal(77, result);
-        Assert.Equal(2, calls);
-    }
-
-    [Fact]
-    public async Task RetryOnExceptionAsync_WhenActionAlwaysFails_ReturnsDefault()
-    {
-        var result = await RetryHelper.RetryOnExceptionAsync(3, TimeSpan.Zero, -1, () =>
-        {
-            throw new Exception("always fails");
-#pragma warning disable CS0162
-            return Task.FromResult(0);
-#pragma warning restore CS0162
-        });
-
-        Assert.Equal(-1, result);
-    }
-
-    [Fact]
-    public async Task RetryOnExceptionAsync_WhenActionAlwaysFails_TriesMaxAttemptsTimes()
-    {
-        int calls = 0;
-
-        await RetryHelper.RetryOnExceptionAsync(4, TimeSpan.Zero, -1, () =>
-        {
-            calls++;
-            throw new Exception("fail");
-#pragma warning disable CS0162
-            return Task.FromResult(0);
-#pragma warning restore CS0162
-        });
-
-        Assert.Equal(4, calls);
-    }
-
-    // ── RetryOnExceptionAsync (void) ──────────────────────────────────────────
-    // NOTE: Same infinite loop bug as the sync void overload.
-
-    [Fact(Skip = "RetryOnExceptionAsync void overload loops infinitely on success (missing return/break after await action())")]
-    public async Task RetryOnExceptionAsync_Void_WhenActionSucceedsImmediately_CompletesOnce()
-    {
-        bool ran = false;
-        await RetryHelper.RetryOnExceptionAsync(3, TimeSpan.Zero, () => { ran = true; return Task.CompletedTask; });
-        Assert.True(ran);
-    }
-
-    [Fact]
-    public async Task RetryOnExceptionAsync_Void_WhenActionAlwaysFails_TriesMaxAttemptsTimes()
-    {
-        int calls = 0;
-
-        await RetryHelper.RetryOnExceptionAsync(3, TimeSpan.Zero, () =>
-        {
-            calls++;
-            throw new Exception("fail");
-#pragma warning disable CS0162
-            return Task.CompletedTask;
-#pragma warning restore CS0162
-        });
-
-        Assert.Equal(3, calls);
-    }
-}
diff --git a/LANCommander.SDK.Tests/Helpers/TextFileHelperTests.cs b/LANCommander.SDK.Tests/Helpers/TextFileHelperTests.cs
deleted file mode 100644
index c39ef5e7..00000000
--- a/LANCommander.SDK.Tests/Helpers/TextFileHelperTests.cs
+++ /dev/null
@@ -1,141 +0,0 @@
-using LANCommander.SDK.Helpers;
-using System.Text.RegularExpressions;
-
-namespace LANCommander.SDK.Tests.Helpers;
-
-public class TextFileHelperTests : IDisposable
-{
-    private readonly string _tempDir;
-
-    public TextFileHelperTests()
-    {
-        _tempDir = Path.Combine(Path.GetTempPath(), $"lc-textfile-tests-{Guid.NewGuid()}");
-        Directory.CreateDirectory(_tempDir);
-    }
-
-    public void Dispose()
-    {
-        if (Directory.Exists(_tempDir))
-            Directory.Delete(_tempDir, true);
-    }
-
-    private string WriteTemp(string content)
-    {
-        var path = Path.Combine(_tempDir, $"{Guid.NewGuid():N}.txt");
-        File.WriteAllText(path, content);
-        return path;
-    }
-
-    // ── Error handling ────────────────────────────────────────────────────────
-
-    [Fact]
-    public void ReplaceAll_WhenFileNotFound_ThrowsFileNotFoundException()
-    {
-        var path = Path.Combine(_tempDir, "nonexistent.txt");
-
-        Assert.Throws<FileNotFoundException>(() =>
-            TextFileHelper.ReplaceAll(path, "pattern", "replacement"));
-    }
-
-    // ── Matching and replacement ───────────────────────────────────────────────
-
-    [Fact]
-    public void ReplaceAll_WhenPatternMatches_ReturnsUpdatedContent()
-    {
-        var path = WriteTemp("Hello World");
-
-        var result = TextFileHelper.ReplaceAll(path, "World", "Earth");
-
-        Assert.Equal("Hello Earth", result);
-    }
-
-    [Fact]
-    public void ReplaceAll_WhenPatternMatches_WritesUpdatedContentToFile()
-    {
-        var path = WriteTemp("Hello World");
-
-        TextFileHelper.ReplaceAll(path, "World", "Earth");
-
-        Assert.Equal("Hello Earth", File.ReadAllText(path));
-    }
-
-    [Fact]
-    public void ReplaceAll_ReplacesAllOccurrences()
-    {
-        var path = WriteTemp("a b a b a");
-
-        var result = TextFileHelper.ReplaceAll(path, "a", "x");
-
-        Assert.Equal("x b x b x", result);
-    }
-
-    // ── No-match behaviour ────────────────────────────────────────────────────
-
-    [Fact]
-    public void ReplaceAll_WhenPatternDoesNotMatch_ReturnsOriginalContent()
-    {
-        var path = WriteTemp("Hello World");
-
-        var result = TextFileHelper.ReplaceAll(path, "ZZZ_NOMATCH", "Replacement");
-
-        Assert.Equal("Hello World", result);
-    }
-
-    [Fact]
-    public void ReplaceAll_WhenPatternDoesNotMatch_FileContentIsUnchanged()
-    {
-        var original = "Hello World";
-        var path = WriteTemp(original);
-
-        TextFileHelper.ReplaceAll(path, "ZZZ_NOMATCH", "Replacement");
-
-        Assert.Equal(original, File.ReadAllText(path));
-    }
-
-    // ── Default options ───────────────────────────────────────────────────────
-
-    [Fact]
-    public void ReplaceAll_DefaultOptions_IsCaseInsensitive()
-    {
-        var path = WriteTemp("Hello WORLD");
-
-        var result = TextFileHelper.ReplaceAll(path, "world", "Earth");
-
-        Assert.Equal("Hello Earth", result);
-    }
-
-    [Fact]
-    public void ReplaceAll_DefaultOptions_IsMultiline()
-    {
-        // ^ matches start of each line in Multiline mode
-        var path = WriteTemp("line1\nline2\nline3");
-
-        var result = TextFileHelper.ReplaceAll(path, "^line", "row");
-
-        Assert.Contains("row1", result);
-        Assert.Contains("row2", result);
-        Assert.Contains("row3", result);
-    }
-
-    // ── Custom options ────────────────────────────────────────────────────────
-
-    [Fact]
-    public void ReplaceAll_WithCaseSensitiveOptions_DoesNotMatchWrongCase()
-    {
-        var path = WriteTemp("Hello WORLD");
-
-        var result = TextFileHelper.ReplaceAll(path, "world", "Earth", RegexOptions.None);
-
-        Assert.Equal("Hello WORLD", result);
-    }
-
-    [Fact]
-    public void ReplaceAll_WithCaptureGroups_SubstitutionGroupsAreExpanded()
-    {
-        var path = WriteTemp("2024-01-15");
-
-        var result = TextFileHelper.ReplaceAll(path, @"(\d{4})-(\d{2})-(\d{2})", "$3/$2/$1");
-
-        Assert.Equal("15/01/2024", result);
-    }
-}
diff --git a/LANCommander.SDK.Tests/Install/GameInstallationFileListEntryTests.cs b/LANCommander.SDK.Tests/Install/GameInstallationFileListEntryTests.cs
deleted file mode 100644
index e52ba3c1..00000000
--- a/LANCommander.SDK.Tests/Install/GameInstallationFileListEntryTests.cs
+++ /dev/null
@@ -1,131 +0,0 @@
-using LANCommander.SDK.Services;
-using ManifestGame = LANCommander.SDK.Models.Manifest.Game;
-
-namespace LANCommander.SDK.Tests.Install;
-
-public class GameInstallationFileListEntryTests
-{
-    private static GameInstallationFileListEntry MakeEntry(params string[] entryPaths)
-    {
-        var entry = new GameInstallationFileListEntry();
-        entry.AddFiles(entryPaths.Select(p => new GameInstallationFileListEntry.FileEntry
-        {
-            EntryPath = p,
-            LocalPath = p
-        }));
-        return entry;
-    }
-
-    [Fact]
-    public void Merge_AddsFilesFromOtherEntry()
-    {
-        var target = new GameInstallationFileListEntry();
-        var source = MakeEntry("game.exe", "readme.txt");
-
-        target.Merge(source);
-
-        Assert.Equal(2, target.Files.Count);
-    }
-
-    [Fact]
-    public void Merge_DoesNotAddDuplicateFiles()
-    {
-        var target = MakeEntry("game.exe");
-        var source = MakeEntry("game.exe", "readme.txt");
-
-        target.Merge(source);
-
-        Assert.Equal(2, target.Files.Count);
-        Assert.Single(target.Files, f => f.EntryPath == "game.exe");
-    }
-
-    [Fact]
-    public void Merge_IsCaseInsensitiveForDuplicateDetection()
-    {
-        var target = MakeEntry("Game.exe");
-        var source = MakeEntry("game.exe", "readme.txt");
-
-        target.Merge(source);
-
-        // "game.exe" should not be added because "Game.exe" already exists (case-insensitive)
-        Assert.Equal(2, target.Files.Count);
-    }
-
-    [Fact]
-    public void Merge_SetsManifestWhenTargetManifestIsNull()
-    {
-        var manifest = new ManifestGame { Id = Guid.NewGuid(), Title = "Test Game" };
-        var target = new GameInstallationFileListEntry();
-        var source = new GameInstallationFileListEntry { Manifest = manifest };
-
-        target.Merge(source);
-
-        Assert.Equal(manifest, target.Manifest);
-    }
-
-    [Fact]
-    public void Merge_DoesNotOverwriteExistingManifest()
-    {
-        var originalManifest = new ManifestGame { Id = Guid.NewGuid(), Title = "Original" };
-        var newManifest = new ManifestGame { Id = Guid.NewGuid(), Title = "New" };
-        var target = new GameInstallationFileListEntry { Manifest = originalManifest };
-        var source = new GameInstallationFileListEntry { Manifest = newManifest };
-
-        target.Merge(source);
-
-        Assert.Equal(originalManifest, target.Manifest);
-    }
-
-    [Fact]
-    public void Merge_WithNullSource_DoesNotThrow()
-    {
-        var target = MakeEntry("game.exe");
-
-        // Merge with a null-files source (empty entry)
-        var emptySource = new GameInstallationFileListEntry();
-        target.Merge(emptySource);
-
-        Assert.Single(target.Files);
-    }
-
-    [Fact]
-    public void AddFile_AddsFileToList()
-    {
-        var entry = new GameInstallationFileListEntry();
-        var file = new GameInstallationFileListEntry.FileEntry
-        {
-            EntryPath = "game.exe",
-            LocalPath = @"C:\Games\game.exe"
-        };
-
-        entry.AddFile(file);
-
-        Assert.Single(entry.Files);
-        Assert.Equal("game.exe", entry.Files[0].EntryPath);
-        Assert.Equal(@"C:\Games\game.exe", entry.Files[0].LocalPath);
-    }
-
-    [Fact]
-    public void AddFiles_AddsMultipleFiles()
-    {
-        var entry = new GameInstallationFileListEntry();
-        var files = new[]
-        {
-            new GameInstallationFileListEntry.FileEntry { EntryPath = "game.exe", LocalPath = @"C:\game.exe" },
-            new GameInstallationFileListEntry.FileEntry { EntryPath = "data.pak", LocalPath = @"C:\data.pak" },
-            new GameInstallationFileListEntry.FileEntry { EntryPath = "readme.txt", LocalPath = @"C:\readme.txt" },
-        };
-
-        entry.AddFiles(files);
-
-        Assert.Equal(3, entry.Files.Count);
-    }
-
-    [Fact]
-    public void AddFile_WithNullArgument_Throws()
-    {
-        var entry = new GameInstallationFileListEntry();
-
-        Assert.Throws<ArgumentNullException>(() => entry.AddFile(null));
-    }
-}
diff --git a/LANCommander.SDK.Tests/Install/GameInstallationFileListTests.cs b/LANCommander.SDK.Tests/Install/GameInstallationFileListTests.cs
deleted file mode 100644
index 0d4e884d..00000000
--- a/LANCommander.SDK.Tests/Install/GameInstallationFileListTests.cs
+++ /dev/null
@@ -1,281 +0,0 @@
-using LANCommander.SDK.Services;
-using ManifestGame = LANCommander.SDK.Models.Manifest.Game;
-
-namespace LANCommander.SDK.Tests.Install;
-
-public class GameInstallationFileListTests
-{
-    private static GameInstallationFileList MakeFileList(string installDir, Guid gameId, params string[] filePaths)
-    {
-        var list = new GameInstallationFileList(installDir, gameId);
-        list.BaseGame.AddFiles(filePaths.Select(p => new GameInstallationFileListEntry.FileEntry
-        {
-            EntryPath = p,
-            LocalPath = p
-        }));
-        return list;
-    }
-
-    // ── MergeBase ────────────────────────────────────────────────────────────
-
-    [Fact]
-    public void MergeBase_MergesBaseGameFilesIntoTarget()
-    {
-        var gameId = Guid.NewGuid();
-        var target = MakeFileList(@"C:\Games\TestGame", gameId, "game.exe");
-        var source = MakeFileList(@"C:\Games\TestGame", gameId, "data.pak");
-
-        target.MergeBase(source);
-
-        Assert.Equal(2, target.BaseGame.Files.Count);
-    }
-
-    [Fact]
-    public void MergeBase_DoesNotDuplicateExistingFiles()
-    {
-        var gameId = Guid.NewGuid();
-        var target = MakeFileList(@"C:\Games\TestGame", gameId, "game.exe");
-        var source = MakeFileList(@"C:\Games\TestGame", gameId, "game.exe", "readme.txt");
-
-        target.MergeBase(source);
-
-        Assert.Equal(2, target.BaseGame.Files.Count);
-    }
-
-    // ── MergeBaseAsDependentGame ──────────────────────────────────────────────
-
-    [Fact]
-    public void MergeBaseAsDependentGame_CreatesDependentGameEntry()
-    {
-        var baseGameId = Guid.NewGuid();
-        var addonId = Guid.NewGuid();
-        var target = MakeFileList(@"C:\Games\TestGame", baseGameId);
-        var addonFileList = MakeFileList(@"C:\Games\TestGame", addonId, "addon.pak");
-
-        target.MergeBaseAsDependentGame(addonId, addonFileList);
-
-        Assert.True(target.DependentGames.ContainsKey(addonId));
-    }
-
-    [Fact]
-    public void MergeBaseAsDependentGame_CopiesFilesFromSourceBaseGame()
-    {
-        var baseGameId = Guid.NewGuid();
-        var addonId = Guid.NewGuid();
-        var target = MakeFileList(@"C:\Games\TestGame", baseGameId);
-        var addonFileList = MakeFileList(@"C:\Games\TestGame", addonId, "addon.pak", "addon_data.pak");
-
-        target.MergeBaseAsDependentGame(addonId, addonFileList);
-
-        Assert.Equal(2, target.DependentGames[addonId].BaseGame.Files.Count);
-    }
-
-    [Fact]
-    public void MergeBaseAsDependentGame_SetsManifestOnNewDependentGame()
-    {
-        var baseGameId = Guid.NewGuid();
-        var addonId = Guid.NewGuid();
-        var manifest = new ManifestGame { Id = addonId, Title = "Test Addon" };
-        var target = MakeFileList(@"C:\Games\TestGame", baseGameId);
-        var addonFileList = MakeFileList(@"C:\Games\TestGame", addonId);
-        addonFileList.BaseGame.Manifest = manifest;
-
-        target.MergeBaseAsDependentGame(addonId, addonFileList);
-
-        Assert.Equal(manifest, target.DependentGames[addonId].BaseGame.Manifest);
-    }
-
-    [Fact]
-    public void MergeBaseAsDependentGame_MergesIntoExistingDependentGame()
-    {
-        var baseGameId = Guid.NewGuid();
-        var addonId = Guid.NewGuid();
-        var target = MakeFileList(@"C:\Games\TestGame", baseGameId);
-
-        var firstAddonFiles = MakeFileList(@"C:\Games\TestGame", addonId, "file1.pak");
-        target.MergeBaseAsDependentGame(addonId, firstAddonFiles);
-
-        var secondAddonFiles = MakeFileList(@"C:\Games\TestGame", addonId, "file2.pak");
-        target.MergeBaseAsDependentGame(addonId, secondAddonFiles);
-
-        Assert.Single(target.DependentGames);
-        Assert.Equal(2, target.DependentGames[addonId].BaseGame.Files.Count);
-    }
-
-    [Fact]
-    public void MergeBaseAsDependentGame_DoesNotDuplicateFilesOnSecondMerge()
-    {
-        var baseGameId = Guid.NewGuid();
-        var addonId = Guid.NewGuid();
-        var target = MakeFileList(@"C:\Games\TestGame", baseGameId);
-
-        var addonFiles = MakeFileList(@"C:\Games\TestGame", addonId, "shared.pak");
-        target.MergeBaseAsDependentGame(addonId, addonFiles);
-        target.MergeBaseAsDependentGame(addonId, addonFiles);
-
-        Assert.Single(target.DependentGames[addonId].BaseGame.Files);
-    }
-
-    // ── MergeDependentGames ───────────────────────────────────────────────────
-
-    [Fact]
-    public void MergeDependentGames_CopiesDependentGamesFromSource()
-    {
-        var baseGameId = Guid.NewGuid();
-        var addonId = Guid.NewGuid();
-
-        var source = MakeFileList(@"C:\Games\TestGame", baseGameId);
-        var addonFileList = MakeFileList(@"C:\Games\TestGame", addonId, "addon.pak");
-        source.MergeBaseAsDependentGame(addonId, addonFileList);
-
-        var target = MakeFileList(@"C:\Games\TestGame", baseGameId);
-        target.MergeDependentGames(source);
-
-        Assert.True(target.DependentGames.ContainsKey(addonId));
-    }
-
-    [Fact]
-    public void MergeDependentGames_WithNullSource_DoesNotThrow()
-    {
-        var gameId = Guid.NewGuid();
-        var target = MakeFileList(@"C:\Games\TestGame", gameId);
-
-        target.MergeDependentGames(null);
-
-        Assert.Empty(target.DependentGames);
-    }
-
-    [Fact]
-    public void MergeDependentGames_WithEmptySource_LeavesTargetUnchanged()
-    {
-        var gameId = Guid.NewGuid();
-        var target = MakeFileList(@"C:\Games\TestGame", gameId);
-        var emptySource = MakeFileList(@"C:\Games\TestGame", gameId);
-
-        target.MergeDependentGames(emptySource);
-
-        Assert.Empty(target.DependentGames);
-    }
-
-    // ── Merge (combined) ──────────────────────────────────────────────────────
-
-    [Fact]
-    public void Merge_MergesBothBaseGameAndDependentGames()
-    {
-        var baseGameId = Guid.NewGuid();
-        var addonId = Guid.NewGuid();
-
-        var source = MakeFileList(@"C:\Games\TestGame", baseGameId, "new_base_file.pak");
-        var addonFileList = MakeFileList(@"C:\Games\TestGame", addonId, "addon.pak");
-        source.MergeBaseAsDependentGame(addonId, addonFileList);
-
-        var target = MakeFileList(@"C:\Games\TestGame", baseGameId, "existing_base_file.pak");
-        target.Merge(source);
-
-        Assert.Equal(2, target.BaseGame.Files.Count);
-        Assert.True(target.DependentGames.ContainsKey(addonId));
-    }
-
-    // ── ToFlatDistinctFileEntries ─────────────────────────────────────────────
-
-    [Fact]
-    public void ToFlatDistinctFileEntries_ReturnsBaseGameFiles()
-    {
-        var gameId = Guid.NewGuid();
-        var list = MakeFileList(@"C:\Games\TestGame", gameId, "game.exe", "data.pak");
-
-        var entries = list.ToFlatDistinctFileEntries().ToList();
-
-        Assert.Equal(2, entries.Count);
-    }
-
-    [Fact]
-    public void ToFlatDistinctFileEntries_IncludesDependentGameFiles()
-    {
-        var baseGameId = Guid.NewGuid();
-        var addonId = Guid.NewGuid();
-        var list = MakeFileList(@"C:\Games\TestGame", baseGameId, "game.exe");
-        var addonFileList = MakeFileList(@"C:\Games\TestGame", addonId, "addon.pak");
-        list.MergeBaseAsDependentGame(addonId, addonFileList);
-
-        var entries = list.ToFlatDistinctFileEntries().ToList();
-
-        Assert.Equal(2, entries.Count);
-        Assert.Contains(entries, e => e.EntryPath == "game.exe");
-        Assert.Contains(entries, e => e.EntryPath == "addon.pak");
-    }
-
-    [Fact]
-    public void ToFlatDistinctFileEntries_DeduplicatesFilesAcrossBaseAndDependentGames()
-    {
-        var baseGameId = Guid.NewGuid();
-        var addonId = Guid.NewGuid();
-
-        // Same file path in both base game and addon
-        var list = MakeFileList(@"C:\Games\TestGame", baseGameId, "shared.cfg");
-        var addonFileList = MakeFileList(@"C:\Games\TestGame", addonId, "shared.cfg", "addon.pak");
-        list.MergeBaseAsDependentGame(addonId, addonFileList);
-
-        var entries = list.ToFlatDistinctFileEntries().ToList();
-
-        // shared.cfg should appear only once, addon.pak once
-        Assert.Equal(2, entries.Count);
-        Assert.Single(entries.Where(e => e.EntryPath.Equals("shared.cfg", StringComparison.OrdinalIgnoreCase)));
-    }
-
-    [Fact]
-    public void ToFlatDistinctFileEntries_BaseGameFileWinsOverDependentOnDuplicate()
-    {
-        var baseGameId = Guid.NewGuid();
-        var addonId = Guid.NewGuid();
-        const string sharedPath = "shared.cfg";
-        const string baseLocalPath = @"C:\base\shared.cfg";
-        const string addonLocalPath = @"C:\addon\shared.cfg";
-
-        var list = new GameInstallationFileList(@"C:\Games\TestGame", baseGameId);
-        list.BaseGame.AddFile(new GameInstallationFileListEntry.FileEntry
-        {
-            EntryPath = sharedPath,
-            LocalPath = baseLocalPath
-        });
-
-        var addonFileList = new GameInstallationFileList(@"C:\Games\TestGame", addonId);
-        addonFileList.BaseGame.AddFile(new GameInstallationFileListEntry.FileEntry
-        {
-            EntryPath = sharedPath,
-            LocalPath = addonLocalPath
-        });
-        list.MergeBaseAsDependentGame(addonId, addonFileList);
-
-        var entries = list.ToFlatDistinctFileEntries().ToList();
-
-        // GroupBy + First means the base game's entry wins
-        var entry = Assert.Single(entries.Where(e => e.EntryPath == sharedPath));
-        Assert.Equal(baseLocalPath, entry.LocalPath);
-    }
-
-    [Fact]
-    public void ToFlatDistinctFileEntries_WithMultipleDependentGames_ReturnsAllFiles()
-    {
-        var baseGameId = Guid.NewGuid();
-        var addon1Id = Guid.NewGuid();
-        var addon2Id = Guid.NewGuid();
-
-        var list = MakeFileList(@"C:\Games\TestGame", baseGameId, "base.exe");
-        list.MergeBaseAsDependentGame(addon1Id, MakeFileList(@"C:\Games\TestGame", addon1Id, "addon1.pak"));
-        list.MergeBaseAsDependentGame(addon2Id, MakeFileList(@"C:\Games\TestGame", addon2Id, "addon2.pak"));
-
-        var entries = list.ToFlatDistinctFileEntries().ToList();
-
-        Assert.Equal(3, entries.Count);
-    }
-
-    [Fact]
-    public void Empty_ReturnsInstanceWithNullInstallDirectory()
-    {
-        var empty = GameInstallationFileList.Empty;
-
-        Assert.Null(empty.InstallDirectory);
-        Assert.Empty(empty.DependentGames);
-    }
-}
diff --git a/LANCommander.SDK.Tests/Install/InstallResultTests.cs b/LANCommander.SDK.Tests/Install/InstallResultTests.cs
index e093c294..45705d10 100644
--- a/LANCommander.SDK.Tests/Install/InstallResultTests.cs
+++ b/LANCommander.SDK.Tests/Install/InstallResultTests.cs
@@ -46,19 +46,4 @@ public class InstallResultTests
         Assert.NotNull(result.FileList);
     }
 
-    [Fact]
-    public void InstallDirectory_ReflectsChangeInFileList()
-    {
-        var gameId = Guid.NewGuid();
-        var originalDir = @"C:\Games\Original";
-        var newDir = @"C:\Games\New";
-
-        var result = new InstallResult(originalDir, gameId)
-        {
-            InstallDirectory = newDir
-        };
-
-        Assert.Equal(newDir, result.InstallDirectory);
-        Assert.Equal(newDir, result.FileList.InstallDirectory);
-    }
 }
diff --git a/LANCommander.SDK.Tests/SaveService.cs b/LANCommander.SDK.Tests/SaveService.cs
index d279d65b..cc1f0d80 100644
--- a/LANCommander.SDK.Tests/SaveService.cs
+++ b/LANCommander.SDK.Tests/SaveService.cs
@@ -102,41 +102,5 @@ namespace LANCommander.SDK.Tests
             Assert.Equal("{InstallDir}/base/autoexec.cfg", entry.ActualPath);
         }
 
-        [Fact]
-        public void RegexInstallDirectorySavePathsShouldWork()
-        {
-            // Arrange
-            var savePath = new SavePath
-            {
-                Id = Guid.NewGuid(),
-                Path = "base\\.*.cfg",
-                WorkingDirectory = "{InstallDir}",
-                Type = Enums.SavePathType.File,
-                IsRegex = true
-            };
-            var installDirectory = Path.Combine(Path.GetTempPath(), savePath.Id.ToString());
-
-            Directory.CreateDirectory(installDirectory);
-            Directory.CreateDirectory(Path.Combine(installDirectory, "base"));
-            File.WriteAllText(Path.Combine(installDirectory, "base", "autoexec.cfg"), savePath.Id.ToString());
-            File.WriteAllText(Path.Combine(installDirectory, "base", "player.cfg"), savePath.Id.ToString());
-
-            // Act
-            var entries = Saves.GetFileSavePathEntries(savePath, installDirectory);
-
-            // Assert
-            Assert.Equal(2, entries.Count());
-            Assert.True(File.Exists(Path.Combine($"{Path.GetTempPath()}\\{savePath.Id}\\base\\autoexec.cfg")));
-            Assert.True(File.Exists(Path.Combine($"{Path.GetTempPath()}\\{savePath.Id}\\base\\player.cfg")));
-
-            var autoexec = entries.First();
-            var player = entries.Last();
-
-            Assert.Equal("base/autoexec.cfg", autoexec.ArchivePath);
-            Assert.Equal("{InstallDir}/base/autoexec.cfg", autoexec.ActualPath);
-
-            Assert.Equal("base/player.cfg", player.ArchivePath);
-            Assert.Equal("{InstallDir}/base/player.cfg", player.ActualPath);
-        }
     }
 }
diff --git a/LANCommander.SDK.Tests/Saves/SaveDownloadTests.cs b/LANCommander.SDK.Tests/Saves/SaveDownloadTests.cs
new file mode 100644
index 00000000..b1e0ace7
--- /dev/null
+++ b/LANCommander.SDK.Tests/Saves/SaveDownloadTests.cs
@@ -0,0 +1,396 @@
+using System.IO.Compression;
+using LANCommander.SDK.Enums;
+using LANCommander.SDK.Extensions;
+using LANCommander.SDK.Helpers;
+using LANCommander.SDK.Services;
+using LANCommander.SDK.Tests.Fixtures;
+using LANCommander.SDK.Utilities;
+using ManifestGame = LANCommander.SDK.Models.Manifest.Game;
+using ManifestSavePath = LANCommander.SDK.Models.Manifest.SavePath;
+
+namespace LANCommander.SDK.Tests.Saves;
+
+/// <summary>
+/// Tests the save download + extraction cycle.
+///
+/// HTTP calls are not exercised.  Instead, the save archive is pre-built on-disk
+/// using <see cref="SavePacker"/> and restored with the same file-movement logic
+/// that <c>SaveClient.DownloadAsync</c> uses, giving us full coverage of the
+/// extraction flow without needing a running server.
+/// </summary>
+public class SaveDownloadTests : IDisposable
+{
+    private readonly string _tempDir;
+
+    // Only the filesystem / pure-computation methods are exercised here;
+    // API-calling members are never invoked, so all DI deps can be null.
+    private readonly SaveClient _saveClient = new(null, null, null, null);
+
+    public SaveDownloadTests()
+    {
+        _tempDir = Path.Combine(Path.GetTempPath(), $"lc-save-download-{Guid.NewGuid()}");
+        Directory.CreateDirectory(_tempDir);
+    }
+
+    public void Dispose()
+    {
+        if (Directory.Exists(_tempDir))
+            Directory.Delete(_tempDir, true);
+    }
+
+    // ── FakeGameFixture – structure sanity checks ─────────────────────────────
+
+    [Fact]
+    public void FakeGame_ManifestWrittenToDisk()
+    {
+        using var fixture = new FakeGameFixture();
+
+        Assert.True(ManifestHelper.Exists(fixture.InstallDirectory, fixture.GameId));
+    }
+
+    [Fact]
+    public void FakeGame_SaveFilesExistOnDisk()
+    {
+        using var fixture = new FakeGameFixture();
+
+        Assert.True(File.Exists(fixture.SaveFileSlot1Path));
+        Assert.True(File.Exists(fixture.SaveFileSlot2Path));
+        Assert.True(File.Exists(fixture.ConfigFilePath));
+    }
+
+    [Fact]
+    public void FakeGame_ManifestContainsTwoKeys()
+    {
+        using var fixture = new FakeGameFixture();
+
+        Assert.Equal(2, fixture.Manifest.Keys.Count);
+    }
+
+    [Fact]
+    public void FakeGame_ManifestContainsExpectedScriptTypes()
+    {
+        using var fixture = new FakeGameFixture();
+        var types = fixture.Manifest.Scripts.Select(s => s.Type).ToList();
+
+        Assert.Contains(ScriptType.Install,    types);
+        Assert.Contains(ScriptType.Uninstall,  types);
+        Assert.Contains(ScriptType.BeforeStart,types);
+        Assert.Contains(ScriptType.AfterStop,  types);
+        Assert.Contains(ScriptType.NameChange, types);
+        Assert.Contains(ScriptType.KeyChange,  types);
+    }
+
+    [Fact]
+    public void FakeGame_ManifestContainsThreeMediaItems()
+    {
+        using var fixture = new FakeGameFixture();
+
+        Assert.Equal(3, fixture.Manifest.Media.Count);
+    }
+
+    [Fact]
+    public void FakeGame_ManifestContainsCoverIconAndBackground()
+    {
+        using var fixture = new FakeGameFixture();
+        var types = fixture.Manifest.Media.Select(m => m.Type).ToList();
+
+        Assert.Contains(MediaType.Cover,      types);
+        Assert.Contains(MediaType.Icon,       types);
+        Assert.Contains(MediaType.Background, types);
+    }
+
+    [Fact]
+    public void FakeGame_ScriptFilesExistOnDisk()
+    {
+        using var fixture = new FakeGameFixture();
+
+        var scriptTypes = new[]
+        {
+            ScriptType.Install, ScriptType.Uninstall,
+            ScriptType.BeforeStart, ScriptType.AfterStop,
+            ScriptType.NameChange, ScriptType.KeyChange
+        };
+
+        foreach (var type in scriptTypes)
+        {
+            var path = ScriptHelper.GetScriptFilePath(fixture.InstallDirectory, fixture.GameId, type);
+            Assert.True(File.Exists(path), $"Script file missing for {type}: {path}");
+        }
+    }
+
+    // ── Packed-archive structure ──────────────────────────────────────────────
+
+    [Fact]
+    public async Task PackedSave_ContainsManifestYml()
+    {
+        using var fixture = new FakeGameFixture();
+
+        var stream = await BuildArchiveStreamAsync(fixture.InstallDirectory, fixture.Manifest);
+        var keys = EntryKeys(stream);
+
+        Assert.Contains(keys, k => string.Equals(k, "Manifest.yml", StringComparison.OrdinalIgnoreCase));
+    }
+
+    [Fact]
+    public async Task PackedSave_SavesDirEntries_PrefixedWithCorrectSavePathId()
+    {
+        using var fixture = new FakeGameFixture();
+        using var packer  = new SavePacker(fixture.InstallDirectory);
+        packer.AddPath(fixture.SavesDirSavePath);
+
+        var keys           = EntryKeys(await packer.PackAsync());
+        var expectedPrefix = $"Files/{fixture.SavesDirSavePath.Id}/";
+
+        Assert.All(keys, k => Assert.StartsWith(expectedPrefix, k));
+    }
+
+    [Fact]
+    public async Task PackedSave_ConfigFileEntry_PrefixedWithCorrectSavePathId()
+    {
+        using var fixture = new FakeGameFixture();
+        using var packer  = new SavePacker(fixture.InstallDirectory);
+        packer.AddPath(fixture.ConfigFileSavePath);
+
+        var keys           = EntryKeys(await packer.PackAsync());
+        var expectedPrefix = $"Files/{fixture.ConfigFileSavePath.Id}/";
+
+        Assert.All(keys, k => Assert.StartsWith(expectedPrefix, k));
+    }
+
+    [Fact]
+    public async Task PackedSave_AllSaveFiles_ArePresent()
+    {
+        using var fixture = new FakeGameFixture();
+
+        var stream = await BuildArchiveStreamAsync(fixture.InstallDirectory, fixture.Manifest);
+        var keys   = EntryKeys(stream);
+
+        Assert.Contains(keys, k => k.EndsWith("slot1.sav"));
+        Assert.Contains(keys, k => k.EndsWith("slot2.sav"));
+        Assert.Contains(keys, k => k.EndsWith("config.cfg"));
+    }
+
+    // ── Round-trip: pack → write to disk → extract → restore ─────────────────
+
+    [Fact]
+    public async Task RoundTrip_SavesDirFiles_LandInDestInstallDirectory()
+    {
+        using var fixture = new FakeGameFixture();
+
+        var archivePath = await WriteSaveArchiveAsync(fixture.InstallDirectory, fixture.Manifest);
+        var destDir     = CreateDestDir();
+
+        RestoreSaveArchive(archivePath, destDir, fixture.Manifest);
+
+        Assert.True(File.Exists(Path.Combine(destDir, "saves", "slot1.sav")));
+        Assert.True(File.Exists(Path.Combine(destDir, "saves", "slot2.sav")));
+    }
+
+    [Fact]
+    public async Task RoundTrip_ConfigFile_LandsInDestInstallDirectory()
+    {
+        using var fixture = new FakeGameFixture();
+
+        var archivePath = await WriteSaveArchiveAsync(fixture.InstallDirectory, fixture.Manifest);
+        var destDir     = CreateDestDir();
+
+        RestoreSaveArchive(archivePath, destDir, fixture.Manifest);
+
+        Assert.True(File.Exists(Path.Combine(destDir, "config.cfg")));
+    }
+
+    [Fact]
+    public async Task RoundTrip_SaveContents_ArePreserved()
+    {
+        using var fixture = new FakeGameFixture();
+
+        var archivePath = await WriteSaveArchiveAsync(fixture.InstallDirectory, fixture.Manifest);
+        var destDir     = CreateDestDir();
+
+        RestoreSaveArchive(archivePath, destDir, fixture.Manifest);
+
+        Assert.Equal(FakeGameFixture.Slot1Content,  File.ReadAllText(Path.Combine(destDir, "saves", "slot1.sav")));
+        Assert.Equal(FakeGameFixture.Slot2Content,  File.ReadAllText(Path.Combine(destDir, "saves", "slot2.sav")));
+        Assert.Equal(FakeGameFixture.ConfigContent, File.ReadAllText(Path.Combine(destDir, "config.cfg")));
+    }
+
+    [Fact]
+    public async Task RoundTrip_MultipleSavePaths_AllFilesRestored()
+    {
+        using var fixture = new FakeGameFixture();
+
+        var archivePath = await WriteSaveArchiveAsync(fixture.InstallDirectory, fixture.Manifest);
+        var destDir     = CreateDestDir();
+
+        RestoreSaveArchive(archivePath, destDir, fixture.Manifest);
+
+        Assert.True(File.Exists(Path.Combine(destDir, "saves", "slot1.sav")));
+        Assert.True(File.Exists(Path.Combine(destDir, "saves", "slot2.sav")));
+        Assert.True(File.Exists(Path.Combine(destDir, "config.cfg")));
+    }
+
+    [Fact]
+    public async Task RoundTrip_OverwritesExistingStaleFile()
+    {
+        using var fixture = new FakeGameFixture();
+
+        var archivePath = await WriteSaveArchiveAsync(fixture.InstallDirectory, fixture.Manifest);
+        var destDir     = CreateDestDir();
+
+        // Pre-populate destination with stale data
+        Directory.CreateDirectory(Path.Combine(destDir, "saves"));
+        File.WriteAllText(Path.Combine(destDir, "saves", "slot1.sav"), "STALE_CONTENT");
+
+        RestoreSaveArchive(archivePath, destDir, fixture.Manifest);
+
+        Assert.Equal(FakeGameFixture.Slot1Content, File.ReadAllText(Path.Combine(destDir, "saves", "slot1.sav")));
+    }
+
+    [Fact]
+    public async Task RoundTrip_WithRegexSavePath_OnlyMatchingFilesRestored()
+    {
+        // Arrange – a game that saves only .sav files via a regex save path
+        var sourceDir = CreateDestDir();
+        Directory.CreateDirectory(Path.Combine(sourceDir, "saves"));
+        File.WriteAllText(Path.Combine(sourceDir, "saves", "slot1.sav"), "SLOT1");
+        File.WriteAllText(Path.Combine(sourceDir, "saves", "slot2.sav"), "SLOT2");
+        File.WriteAllText(Path.Combine(sourceDir, "saves", "notes.txt"), "NOTES"); // must NOT be packed
+
+        var regexSavePath = new ManifestSavePath
+        {
+            Id               = Guid.NewGuid(),
+            Type             = SavePathType.File,
+            Path             = @"\.sav$",
+            WorkingDirectory = "{InstallDir}",
+            IsRegex          = true
+        };
+
+        var manifest = new ManifestGame
+        {
+            Id        = Guid.NewGuid(),
+            Title     = "Regex Save Game",
+            SavePaths = new List<ManifestSavePath> { regexSavePath }
+        };
+
+        var archivePath = await WriteSaveArchiveAsync(sourceDir, manifest);
+        var destDir     = CreateDestDir();
+
+        RestoreSaveArchive(archivePath, destDir, manifest);
+
+        Assert.True(File.Exists(Path.Combine(destDir, "saves", "slot1.sav")));
+        Assert.True(File.Exists(Path.Combine(destDir, "saves", "slot2.sav")));
+        Assert.False(File.Exists(Path.Combine(destDir, "saves", "notes.txt")));
+    }
+
+    // ── Helpers ───────────────────────────────────────────────────────────────
+
+    /// <summary>
+    /// Packs all save paths from <paramref name="manifest"/> and writes the resulting
+    /// ZIP archive to a temp file.  Returns the path to that file.
+    /// </summary>
+    private async Task<string> WriteSaveArchiveAsync(string installDirectory, ManifestGame manifest)
+    {
+        var stream = await BuildArchiveStreamAsync(installDirectory, manifest);
+
+        var archivePath = Path.Combine(_tempDir, $"save-{Guid.NewGuid()}.zip");
+        stream.Position = 0;
+
+        await using var fs = File.Create(archivePath);
+        await stream.CopyToAsync(fs);
+
+        return archivePath;
+    }
+
+    private static async Task<Stream> BuildArchiveStreamAsync(string installDirectory, ManifestGame manifest)
+    {
+        using var packer = new SavePacker(installDirectory);
+
+        if (manifest.SavePaths?.Any() == true)
+            packer.AddPaths(manifest.SavePaths);
+
+        await packer.AddManifestAsync(manifest);
+
+        var packed = await packer.PackAsync();
+
+        // Copy to a fresh MemoryStream so the caller owns a non-disposed buffer.
+        var copy = new MemoryStream();
+        packed.Position = 0;
+        await packed.CopyToAsync(copy);
+        copy.Position = 0;
+        return copy;
+    }
+
+    /// <summary>
+    /// Restores a save archive to <paramref name="installDirectory"/>.
+    ///
+    /// Mirrors the file-movement block from <c>SaveClient.DownloadAsync</c> exactly,
+    /// replacing only the HTTP download step with the pre-built archive file.
+    /// This makes the test a faithful integration test of the extraction logic.
+    /// </summary>
+    private void RestoreSaveArchive(string archivePath, string installDirectory, ManifestGame manifest)
+    {
+        var tempLocation = Path.Combine(Path.GetTempPath(), $"lc-restore-{Guid.NewGuid()}");
+
+        try
+        {
+            Directory.CreateDirectory(tempLocation);
+            ZipFile.ExtractToDirectory(archivePath, tempLocation, overwriteFiles: true);
+
+            // Mirror legacy-fallback from SaveClient.DownloadAsync
+            var tempFilesRoot = Directory.Exists(Path.Combine(tempLocation, "Files")) ? "Files" : "Saves";
+
+            foreach (var savePath in manifest.SavePaths.Where(sp => sp.Type == SavePathType.File))
+            {
+                var entries = _saveClient.GetFileSavePathEntries(savePath, installDirectory) ?? [];
+
+                foreach (var entry in entries)
+                {
+                    var entryPath = Path.Combine(
+                        tempLocation,
+                        tempFilesRoot,
+                        savePath.Id.ToString(),
+                        entry.ArchivePath.Replace('/', Path.DirectorySeparatorChar));
+
+                    var destinationPath = entry.ActualPath.ExpandEnvironmentVariables(installDirectory);
+
+                    if (File.Exists(entryPath))
+                    {
+                        Directory.CreateDirectory(Path.GetDirectoryName(destinationPath)!);
+                        if (File.Exists(destinationPath)) File.Delete(destinationPath);
+                        File.Move(entryPath, destinationPath);
+                    }
+                    else if (Directory.Exists(entryPath))
+                    {
+                        foreach (var entryFile in Directory.GetFiles(entryPath, "*", SearchOption.AllDirectories))
+                        {
+                            var fileDestination = entryFile.Replace(entryPath, destinationPath);
+                            Directory.CreateDirectory(Path.GetDirectoryName(fileDestination)!);
+                            if (File.Exists(fileDestination)) File.Delete(fileDestination);
+                            File.Move(entryFile, fileDestination);
+                        }
+                    }
+                }
+            }
+        }
+        finally
+        {
+            if (Directory.Exists(tempLocation))
+                Directory.Delete(tempLocation, true);
+        }
+    }
+
+    /// <summary>Creates a fresh empty directory under _tempDir for use as a restore destination.</summary>
+    private string CreateDestDir()
+    {
+        var dir = Path.Combine(_tempDir, $"dest-{Guid.NewGuid()}");
+        Directory.CreateDirectory(dir);
+        return dir;
+    }
+
+    private static List<string> EntryKeys(Stream stream)
+    {
+        stream.Position = 0;
+        using var zip = new ZipArchive(stream, ZipArchiveMode.Read, leaveOpen: true);
+        return zip.Entries.Select(e => e.FullName.Replace('\\', '/')).ToList();
+    }
+}
diff --git a/LANCommander.SDK.Tests/Saves/SaveUploadTests.cs b/LANCommander.SDK.Tests/Saves/SaveUploadTests.cs
new file mode 100644
index 00000000..bde30870
--- /dev/null
+++ b/LANCommander.SDK.Tests/Saves/SaveUploadTests.cs
@@ -0,0 +1,277 @@
+using System.IO.Compression;
+using LANCommander.SDK.Enums;
+using LANCommander.SDK.Services;
+using LANCommander.SDK.Tests.Fixtures;
+using LANCommander.SDK.Utilities;
+using ManifestGame = LANCommander.SDK.Models.Manifest.Game;
+using ManifestSavePath = LANCommander.SDK.Models.Manifest.SavePath;
+
+namespace LANCommander.SDK.Tests.Saves;
+
+/// <summary>
+/// Tests the save upload + packing cycle.
+///
+/// <c>SaveClient.UploadAsync</c> ends with an HTTP POST; only the packing half is
+/// exercised here.  <c>SaveClient.PackAsync</c> (no HTTP) and <c>SavePacker</c>
+/// directly are both tested so we cover the path the launcher takes after a game exits.
+/// </summary>
+public class SaveUploadTests : IDisposable
+{
+    private readonly string _tempDir;
+
+    // Only the packing / file-system methods are exercised;
+    // API-calling members are never invoked, so all DI deps can be null.
+    private readonly SaveClient _saveClient = new(null, null, null, null);
+
+    public SaveUploadTests()
+    {
+        _tempDir = Path.Combine(Path.GetTempPath(), $"lc-save-upload-{Guid.NewGuid()}");
+        Directory.CreateDirectory(_tempDir);
+    }
+
+    public void Dispose()
+    {
+        if (Directory.Exists(_tempDir))
+            Directory.Delete(_tempDir, true);
+    }
+
+    // ── SaveClient.PackAsync ──────────────────────────────────────────────────
+
+    [Fact]
+    public async Task PackAsync_ProducesReadableZipStream()
+    {
+        using var fixture = new FakeGameFixture();
+
+        var stream = await _saveClient.PackAsync(fixture.InstallDirectory, fixture.Manifest);
+
+        var ex = Record.Exception(() =>
+        {
+            stream.Position = 0;
+            using var zip = new ZipArchive(stream, ZipArchiveMode.Read, leaveOpen: true);
+            _ = zip.Entries.Count;
+        });
+        Assert.Null(ex);
+    }
+
+    [Fact]
+    public async Task PackAsync_IncludesManifestYml()
+    {
+        using var fixture = new FakeGameFixture();
+
+        var keys = EntryKeys(await _saveClient.PackAsync(fixture.InstallDirectory, fixture.Manifest));
+
+        Assert.Contains(keys, k => string.Equals(k, "Manifest.yml", StringComparison.OrdinalIgnoreCase));
+    }
+
+    [Fact]
+    public async Task PackAsync_IncludesSaveSlotFiles()
+    {
+        using var fixture = new FakeGameFixture();
+
+        var keys = EntryKeys(await _saveClient.PackAsync(fixture.InstallDirectory, fixture.Manifest));
+
+        Assert.Contains(keys, k => k.EndsWith("slot1.sav"));
+        Assert.Contains(keys, k => k.EndsWith("slot2.sav"));
+    }
+
+    [Fact]
+    public async Task PackAsync_IncludesConfigFile()
+    {
+        using var fixture = new FakeGameFixture();
+
+        var keys = EntryKeys(await _saveClient.PackAsync(fixture.InstallDirectory, fixture.Manifest));
+
+        Assert.Contains(keys, k => k.EndsWith("config.cfg"));
+    }
+
+    [Fact]
+    public async Task PackAsync_WithNoSavePaths_ProducesArchiveWithOnlyManifest()
+    {
+        var installDir = Path.Combine(_tempDir, "empty-game");
+        Directory.CreateDirectory(installDir);
+
+        var manifest = new ManifestGame
+        {
+            Id        = Guid.NewGuid(),
+            Title     = "No-Save Game",
+            SavePaths = new List<ManifestSavePath>()
+        };
+
+        var keys = EntryKeys(await _saveClient.PackAsync(installDir, manifest));
+
+        Assert.Single(keys);
+        Assert.Contains(keys, k => string.Equals(k, "Manifest.yml", StringComparison.OrdinalIgnoreCase));
+    }
+
+    [Fact]
+    public async Task PackAsync_WithRegexSavePath_ExcludesNonMatchingFiles()
+    {
+        var installDir = CreateGameDir(
+            ("save1.sav", "SAVE1"),
+            ("save2.sav", "SAVE2"),
+            ("readme.txt", "README"));
+
+        var manifest = new ManifestGame
+        {
+            Id    = Guid.NewGuid(),
+            Title = "Regex Game",
+            SavePaths = new List<ManifestSavePath>
+            {
+                new()
+                {
+                    Id               = Guid.NewGuid(),
+                    Type             = SavePathType.File,
+                    Path             = @"\.sav$",
+                    WorkingDirectory = "{InstallDir}",
+                    IsRegex          = true
+                }
+            }
+        };
+
+        var keys = EntryKeys(await _saveClient.PackAsync(installDir, manifest));
+
+        Assert.DoesNotContain(keys, k => k.EndsWith(".txt"));
+        Assert.Contains(keys, k => k.EndsWith(".sav"));
+    }
+
+    [Fact]
+    public async Task PackAsync_WithMultipleSavePaths_AllFilesIncluded()
+    {
+        using var fixture = new FakeGameFixture();
+
+        var keys = EntryKeys(await _saveClient.PackAsync(fixture.InstallDirectory, fixture.Manifest));
+
+        Assert.Contains(keys, k => k.Contains(fixture.SavesDirSavePath.Id.ToString()));
+        Assert.Contains(keys, k => k.Contains(fixture.ConfigFileSavePath.Id.ToString()));
+    }
+
+    [Fact]
+    public async Task PackAsync_EachSavePath_StoredUnderDistinctIdPrefix()
+    {
+        using var fixture = new FakeGameFixture();
+
+        var keys = EntryKeys(await _saveClient.PackAsync(fixture.InstallDirectory, fixture.Manifest));
+
+        var saveDirKeys = keys.Where(k => k.Contains(fixture.SavesDirSavePath.Id.ToString())).ToList();
+        var configKeys  = keys.Where(k => k.Contains(fixture.ConfigFileSavePath.Id.ToString())).ToList();
+
+        Assert.NotEmpty(saveDirKeys);
+        Assert.NotEmpty(configKeys);
+        Assert.Empty(saveDirKeys.Intersect(configKeys));
+    }
+
+    // ── SavePacker directly ───────────────────────────────────────────────────
+
+    [Fact]
+    public async Task SavePacker_WithFakeGame_ProducesExpectedFileCount()
+    {
+        using var fixture = new FakeGameFixture();
+        using var packer  = new SavePacker(fixture.InstallDirectory);
+
+        packer.AddPaths(fixture.Manifest.SavePaths);
+        await packer.AddManifestAsync(fixture.Manifest);
+
+        // slot1.sav + slot2.sav + config.cfg + Manifest.yml = 4
+        Assert.Equal(4, EntryKeys(await packer.PackAsync()).Count);
+    }
+
+    [Fact]
+    public async Task SavePacker_PackedContent_MatchesOriginalFileContent()
+    {
+        using var fixture = new FakeGameFixture();
+        using var packer  = new SavePacker(fixture.InstallDirectory);
+        packer.AddPath(fixture.ConfigFileSavePath);
+
+        var stream = await packer.PackAsync();
+        stream.Position = 0;
+
+        using var zip         = new ZipArchive(stream, ZipArchiveMode.Read, leaveOpen: true);
+        var       configEntry = zip.Entries.FirstOrDefault(e => e.FullName.EndsWith("config.cfg"));
+
+        Assert.NotNull(configEntry);
+
+        using var reader  = new StreamReader(configEntry.Open());
+        var       content = await reader.ReadToEndAsync();
+
+        Assert.Equal(FakeGameFixture.ConfigContent, content);
+    }
+
+    [Fact]
+    public async Task SavePacker_WithDirectorySavePath_PacksAllFilesInDirectory()
+    {
+        using var fixture = new FakeGameFixture();
+        using var packer  = new SavePacker(fixture.InstallDirectory);
+        packer.AddPath(fixture.SavesDirSavePath);
+
+        var keys = EntryKeys(await packer.PackAsync());
+
+        Assert.Equal(2, keys.Count);
+        Assert.Contains(keys, k => k.EndsWith("slot1.sav"));
+        Assert.Contains(keys, k => k.EndsWith("slot2.sav"));
+    }
+
+    [Fact]
+    public async Task SavePacker_AfterGameExit_NewSaveFileIsIncluded()
+    {
+        using var fixture = new FakeGameFixture();
+
+        // Simulate a new save written after game launch
+        File.WriteAllText(Path.Combine(fixture.SavesDirectory, "slot3.sav"), "NEW_SLOT");
+
+        using var packer = new SavePacker(fixture.InstallDirectory);
+        packer.AddPath(fixture.SavesDirSavePath);
+
+        var keys = EntryKeys(await packer.PackAsync());
+
+        Assert.Contains(keys, k => k.EndsWith("slot3.sav"));
+    }
+
+    [Fact]
+    public async Task SavePacker_AfterGameExit_ModifiedSaveFileContentIsPreserved()
+    {
+        using var fixture = new FakeGameFixture();
+
+        // Simulate the game overwriting slot1 with new data
+        File.WriteAllText(fixture.SaveFileSlot1Path, "UPDATED_SAVE");
+
+        using var packer = new SavePacker(fixture.InstallDirectory);
+        packer.AddPath(fixture.SavesDirSavePath);
+
+        var stream = await packer.PackAsync();
+        stream.Position = 0;
+
+        using var zip   = new ZipArchive(stream, ZipArchiveMode.Read, leaveOpen: true);
+        var       entry = zip.Entries.FirstOrDefault(e => e.FullName.EndsWith("slot1.sav"));
+
+        Assert.NotNull(entry);
+
+        using var reader  = new StreamReader(entry.Open());
+        var       content = await reader.ReadToEndAsync();
+
+        Assert.Equal("UPDATED_SAVE", content);
+    }
+
+    // ── Helpers ───────────────────────────────────────────────────────────────
+
+    private string CreateGameDir(params (string relativePath, string content)[] files)
+    {
+        var dir = Path.Combine(_tempDir, $"game-{Guid.NewGuid()}");
+        Directory.CreateDirectory(dir);
+
+        foreach (var (relativePath, content) in files)
+        {
+            var full = Path.Combine(dir, relativePath);
+            Directory.CreateDirectory(Path.GetDirectoryName(full)!);
+            File.WriteAllText(full, content);
+        }
+
+        return dir;
+    }
+
+    private static List<string> EntryKeys(Stream stream)
+    {
+        stream.Position = 0;
+        using var zip = new ZipArchive(stream, ZipArchiveMode.Read, leaveOpen: true);
+        return zip.Entries.Select(e => e.FullName.Replace('\\', '/')).ToList();
+    }
+}
diff --git a/LANCommander.SDK.Tests/TEST_COVERAGE_PLAN.md b/LANCommander.SDK.Tests/TEST_COVERAGE_PLAN.md
new file mode 100644
index 00000000..5f7e6d4f
--- /dev/null
+++ b/LANCommander.SDK.Tests/TEST_COVERAGE_PLAN.md
@@ -0,0 +1,543 @@
+# LANCommander.SDK — Test Coverage Plan
+
+## Current Status
+
+| Area | Classes | Methods | Tests | Coverage |
+|---|---|---|---|---|
+| Extensions | 8 public | ~20 public | 88 | High |
+| Helpers — `DirectoryHelper` | 1 | 3 | 22 | High |
+| Helpers — `ManifestHelper` | 1 | 9 | 40+ | High |
+| Helpers — `ScriptHelper` | 1 | 6 | 20+ | High |
+| Helpers — `IniHelper` | 1 | 4 | ~20 (via IniHandling/) | Medium |
+| Helpers — `DisplayHelper` | 1 | 1 | 0 | None |
+| Helpers — `EnvironmentHelper` | 1 | 1 | 0 | None |
+| Helpers — `VersionHelper` | 1 | 1 | 0 | None |
+| Utilities — `SavePacker` | 1 | 7 | ~20 | Medium |
+| Utilities — `RegistryExportUtility` | 1 | 1 | 0 | None |
+| Utilities — `RegistryImportUtility` | 1 | 1 | 0 | None |
+| Clients (all 18) | 18 | 100+ | 0 | None |
+| Models with logic | ~5 | ~10 | ~5 | Low |
+
+---
+
+## Test Infrastructure Requirements
+
+Before writing client tests, two pieces of test infrastructure are needed.
+
+### 1. Fake `HttpMessageHandler`
+
+All HTTP clients use `ApiRequestFactory` → `ApiRequestBuilder` → `HttpClient`. The most effective
+isolation strategy is a fake `HttpMessageHandler` that intercepts requests and returns controlled
+responses, without touching a real server.
+
+```csharp
+// Suggested location: LANCommander.SDK.Tests/Infrastructure/FakeHttpMessageHandler.cs
+public class FakeHttpMessageHandler : HttpMessageHandler
+{
+    private readonly Func<HttpRequestMessage, HttpResponseMessage> _handler;
+
+    public FakeHttpMessageHandler(Func<HttpRequestMessage, HttpResponseMessage> handler)
+        => _handler = handler;
+
+    protected override Task<HttpResponseMessage> SendAsync(
+        HttpRequestMessage request, CancellationToken cancellationToken)
+        => Task.FromResult(_handler(request));
+}
+```
+
+For JSON responses, a helper that serializes any object to an `application/json`
+`StringContent` with status 200 reduces boilerplate across all client tests.
+
+### 2. Package References
+
+Add to `LANCommander.SDK.Tests.csproj`:
+
+```xml
+<PackageReference Include="NSubstitute" Version="5.*" />
+```
+
+NSubstitute is used to mock `ILogger<T>`, `ISettingsProvider`, `ITokenProvider`,
+`IConnectionClient`, and other injected dependencies that client constructors require but
+whose behavior is not under test.
+
+### 3. Shared Client Fixtures
+
+Because every client shares the same constructor pattern (`ILogger`, `ApiRequestFactory`, etc.),
+a base class or shared factory method should build a ready-to-use client with a fake
+`HttpMessageHandler` injected, reducing boilerplate to a single line per test.
+
+---
+
+## Coverage Plan
+
+### Priority 1 — Pure Computation (no mocks needed)
+
+These classes have no I/O dependencies and can be tested directly. Most are already covered;
+the gaps are small.
+
+---
+
+#### `VersionHelper.GetCurrentVersion()`
+**File:** `Helpers/VersionHelperTests.cs`
+
+| Test | What it checks |
+|---|---|
+| `GetCurrentVersion_ReturnsNonNullVersion` | Return value is not null |
+| `GetCurrentVersion_ReturnsSemVersion` | Parses into a valid `SemVersion` |
+| `GetCurrentVersion_MajorAndMinorAreNonNegative` | Sanity-check numeric components |
+
+**Notes:** The method reads from the executing assembly's `AssemblyInformationalVersionAttribute`.
+The version available during test runs may be `0.0.0` or similar — tests should assert shape,
+not a specific value.
+
+---
+
+#### `IniHelper` (gap fill)
+**File:** `IniHandling/IniHelperTests.cs`
+
+The existing `IniHandlingTests_MadMilkman` already tests `FromString` and `ToString`
+indirectly via the `ConfigurationTests` data set. The following dedicated tests cover
+`IniHelper`'s own behaviour independently of `MadMilkman` specifics.
+
+| Test | What it checks |
+|---|---|
+| `FromString_WithEmptyString_ReturnsEmptyIniFile` | No sections or keys |
+| `FromString_WithNullString_ThrowsOrReturnsEmpty` | Null safety |
+| `FromString_DefaultOptions_AllowsDuplicateKeys` | Default `IniOptions` behaviour |
+| `ToString_RoundTrip_PreservesAllKeyValues` | Serialise then re-parse matches original |
+| `ToString_WithCustomEncoding_WritesExpectedBytes` | Encoding parameter is respected |
+| `FromString_WithCustomOptions_KeyDuplicateIgnored_TakesFirstValue` | `IniDuplication.Ignored` |
+| `FromString_WithCustomOptions_KeyDuplicateAllowed_RetainsAllValues` | `IniDuplication.Allowed` |
+
+---
+
+#### `ProfileClient.GetAvatarUri()` and `MediaClient` URI/path helpers
+**File:** `Clients/MediaClientPureTests.cs`
+
+These methods are pure string computation inside otherwise network-heavy clients, making them
+good isolated targets.
+
+| Test | Method | What it checks |
+|---|---|---|
+| `GetAbsoluteUrl_WithValidMedia_ReturnsAbsoluteUri` | `MediaClient.GetAbsoluteUrl` | Scheme + host from settings |
+| `GetLocalPath_WithMedia_ReturnsExpectedFormat` | `MediaClient.GetLocalPath(Media)` | FileId + CRC32 path format |
+| `GetLocalPath_WithFileIdAndCrc32_MatchesMediaOverload` | `MediaClient.GetLocalPath(Guid, string)` | Both overloads agree |
+| `GetDownloadPath_ReturnsPathUnderExpectedDirectory` | `MediaClient.GetDownloadPath` | Path structure |
+| `GetAvatarUri_BuildsCorrectUrl` | `ProfileClient.GetAvatarUri` | Host + username in URI |
+| `CalculateChecksumAsync_OnKnownContent_ReturnsExpectedCrc32` | `MediaClient.CalculateChecksumAsync` | File CRC32 is deterministic |
+
+---
+
+### Priority 2 — Helpers with filesystem I/O (already have test infrastructure)
+
+These use the established `IDisposable`+temp-directory pattern from `DirectoryHelperTests`.
+
+---
+
+#### `EnvironmentHelper.IsRunningInContainer()`
+**File:** `Helpers/EnvironmentHelperTests.cs`
+
+The method checks three signals in order:
+1. Existence of `/.dockerenv`
+2. Contents of `/proc/1/cgroup`
+3. Environment variables (`KUBERNETES_SERVICE_HOST`, `container`, `PODMAN_VERSION`, etc.)
+
+Because the checks read real filesystem paths, tests must set up controlled temporary files or
+environment variables rather than relying on the host system's state.
+
+| Test | Setup | What it checks |
+|---|---|---|
+| `IsRunningInContainer_WithDockerenvFile_ReturnsTrue` | Create `{tempDir}/.dockerenv`; inject path | Docker detection via file |
+| `IsRunningInContainer_WithCgroupContainingDocker_ReturnsTrue` | Write `docker` into a temp cgroup file | cgroup-based detection |
+| `IsRunningInContainer_WithCgroupContainingKubernetes_ReturnsTrue` | Write `kubepods` into cgroup | Kubernetes via cgroup |
+| `IsRunningInContainer_WithKubernetesEnvVar_ReturnsTrue` | Set `KUBERNETES_SERVICE_HOST` env var | Kubernetes env var |
+| `IsRunningInContainer_WithContainerEnvVar_ReturnsTrue` | Set `container=podman` env var | Podman/container env var |
+| `IsRunningInContainer_WithNoSignals_ReturnsFalse` | No file, no env var, empty cgroup | Normal environment |
+
+**Notes:** The current implementation reads hardcoded paths (`/.dockerenv`, `/proc/1/cgroup`).
+A thin path-injection seam (or a wrapper method the tests can override) will be needed to avoid
+making these tests host-dependent.
+
+---
+
+#### `DisplayHelper.GetScreen()` — Linux parsing only
+**File:** `Helpers/DisplayHelperTests.cs`
+
+The three Linux code paths (`xrandr`, `xdpyinfo`, `/sys/class/drm`) each parse a specific text
+format. The parsing logic can be tested directly if it is extracted into internal parse methods,
+or indirectly by supplying mock process output.
+
+| Test | What it checks |
+|---|---|
+| `ParseXrandrOutput_WithTypicalOutput_ExtractsBoundsAndRefreshRate` | Width × height × Hz from `xrandr` format |
+| `ParseXrandrOutput_WithMultipleDisplayLines_PicksConnected` | Multiple monitors, picks "connected" line |
+| `ParseXdpyinfoOutput_WithTypicalOutput_ExtractsDimensions` | Width × height from `xdpyinfo` format |
+| `ParseDrmOutput_WithTypicalFilesystemContent_ExtractsDimensions` | `/sys/class/drm/*/modes` format |
+| `GetScreen_WhenNoDisplayServer_ReturnsDefaultOrNull` | Graceful fallback when xrandr is absent |
+
+**Notes:** The private parse helpers are currently inline within `GetScreen()`. Extracting them
+to `internal static` methods would allow direct testing without spawning processes.
+
+---
+
+### Priority 3 — Utilities
+
+---
+
+#### `SavePacker` (gap fill)
+**File:** `Utilities/SavePackerTests.cs` *(add to existing file)*
+
+The existing `SavePackerTests` already cover the primary happy paths. The remaining gaps are:
+
+| Test | What it checks |
+|---|---|
+| `AddPath_WithRegistryType_CallsAddRegistryPath` | `SavePathType.Registry` routes correctly |
+| `AddRegistryPath_OnLinux_ProducesNoEntries` | Registry export is no-op on Linux |
+| `AddPaths_TwoDifferentSavePathIds_EachInOwnSubdirectory` | Partition by `SavePath.Id` in zip |
+| `PackAsync_CalledTwice_ReturnsFreshStreamEachTime` | Idempotency / re-use after pack |
+| `PackAsync_EmptyPacker_ProducesValidZipStream` | Empty archive is still valid ZIP |
+| `AddManifestAsync_CalledTwice_HasManifestRemainsTrue` | No error on duplicate manifest add |
+
+---
+
+#### `RegistryExportUtility` — Windows-only
+**File:** `Utilities/RegistryExportUtilityTests.cs`
+
+These tests only run on Windows. Decorate the class with
+`[PlatformSpecific(TestPlatforms.Windows)]` (or use `Skip` on non-Windows).
+
+| Test | What it checks |
+|---|---|
+| `Export_WithKnownRegistryKey_ProducesRegFileFormat` | Output starts with `Windows Registry Editor` header |
+| `Export_WithStringValue_IncludesRegSz` | `REG_SZ` values appear as `"key"="value"` |
+| `Export_WithDwordValue_IncludesRegDword` | `REG_DWORD` values formatted with hex |
+| `Export_WithExpandStringValue_IncludesRegExpandSz` | `REG_EXPAND_SZ` type tag |
+| `Export_WithMultiStringValue_IncludesRegMultiSz` | Null-separated multi-string encoding |
+| `Export_WithBinaryValue_IncludesRegBinary` | Hex byte sequence format |
+| `Export_WithNonExistentKey_ReturnsEmptyOrThrows` | Error handling for missing keys |
+| `Export_WithNestedSubkeys_RecursivelyCapturesAll` | Deep key trees |
+
+---
+
+#### `RegistryImportUtility` — Windows-only
+**File:** `Utilities/RegistryImportUtilityTests.cs`
+
+| Test | What it checks |
+|---|---|
+| `Import_ValidRegFile_WritesValuesToRegistry` | Round-trip with `RegistryExportUtility` |
+| `Import_WithDeletedKey_RemovesKey` | `-` prefix in `.reg` syntax |
+| `Import_WithMalformedFile_ThrowsOrReturnsError` | Error handling |
+| `Import_WithEmptyFile_DoesNotThrow` | Edge case |
+
+---
+
+### Priority 4 — Clients (require mock HTTP infrastructure)
+
+All clients use `ApiRequestFactory` → `HttpClient`. The recommended approach is to create
+`ApiRequestFactory` with a custom `HttpClient` backed by `FakeHttpMessageHandler`, then
+construct the client under test with that factory.
+
+---
+
+#### `AuthenticationClient`
+**File:** `Clients/AuthenticationClientTests.cs`
+
+| Test | HTTP mock | What it checks |
+|---|---|---|
+| `AuthenticateAsync_WithValidCredentials_ReturnsToken` | POST `/api/Auth/Login` → 200 + `AuthToken` JSON | Token returned and stored |
+| `AuthenticateAsync_WithWrongPassword_ThrowsOrReturnsNull` | POST `/api/Auth/Login` → 401 | Failure handling |
+| `LogoutAsync_SendsDeleteRequest` | POST/DELETE `/api/Auth/Logout` → 200 | Request sent |
+| `RegisterAsync_WithValidData_Succeeds` | POST `/api/Auth/Register` → 200 | No exception |
+| `RegisterAsync_WithConflictingUsername_ThrowsOrReturns` | POST `/api/Auth/Register` → 409 | Conflict handling |
+| `ValidateTokenAsync_WithValidToken_ReturnsTrue` | GET `/api/Auth/Validate` → 200 | True returned |
+| `ValidateTokenAsync_WithExpiredToken_ReturnsFalse` | GET `/api/Auth/Validate` → 401 | False returned |
+| `GetAuthenticationProvidersAsync_ReturnsProviderList` | GET `/api/Auth/GetAuthenticationProviders` → provider JSON | List deserialized |
+| `GetAuthenticationProviderLoginUrl_WithProvider_BuildsCorrectUrl` | No HTTP needed | URI shape correct |
+
+---
+
+#### `GameClient` — metadata and static methods
+**File:** `Clients/GameClientTests.cs`
+
+The `GameClient` is the most complex client (~1800 lines). Focus on the methods that do not
+orchestrate archive downloads, as those are better covered by integration tests.
+
+| Test | HTTP mock | What it checks |
+|---|---|---|
+| `GetAsync_ReturnsDeserializedGameList` | GET `/api/Games` → game list JSON | Correct deserialization |
+| `GetAsync_ById_ReturnsGame` | GET `/api/Games/{id}` → single game JSON | Single game returned |
+| `GetManifestAsync_ReturnsManifest` | GET `/api/Games/{id}/Manifest` → YAML | Manifest deserialized |
+| `GetAddonsAsync_ReturnsAddonList` | GET `/api/Games/{id}/Addons` → addon JSON | Addons listed |
+| `GetToolsAsync_ReturnsToolList` | GET `/api/Games/{id}/Tools` → tool JSON | Tools listed |
+| `CheckForUpdateAsync_WhenUpdateAvailable_ReturnsTrue` | GET `/api/Games/{id}/CheckForUpdate` → `{"updateAvailable":true}` | True returned |
+| `CheckForUpdateAsync_WhenUpToDate_ReturnsFalse` | GET `/api/Games/{id}/CheckForUpdate` → `{"updateAvailable":false}` | False returned |
+| `StartedAsync_SendsRequest` | GET `/api/Games/{id}/Started` → 200 | Request sent to correct URL |
+| `StoppedAsync_SendsRequest` | GET `/api/Games/{id}/Stopped` → 200 | Request sent to correct URL |
+| `GetMetadataDirectoryPath_ReturnsCorrectPath` | No HTTP | Path contains `.lancommander/{id}` |
+| `GetPlayerAlias_WhenFileAbsent_ReturnsEmpty` | No HTTP, temp dir | Empty string returned |
+| `UpdatePlayerAlias_WritesAliasFile` | No HTTP, temp dir | File written, alias readable |
+| `GetCurrentKey_WhenFileAbsent_ReturnsEmpty` | No HTTP, temp dir | Empty string returned |
+| `UpdateCurrentKey_WritesKeyFile` | No HTTP, temp dir | File written, key readable |
+
+---
+
+#### `DepotClient`
+**File:** `Clients/DepotClientTests.cs`
+
+| Test | HTTP mock | What it checks |
+|---|---|---|
+| `GetAsync_ReturnsDepotResults` | GET `/api/Depot` → results JSON | Deserialized correctly |
+| `GetGameAsync_ReturnsDepotGame` | GET `/api/Depot/Games/{id}` → game JSON | Single game deserialized |
+| `GetGameAsync_WithServerError_Throws` | GET `/api/Depot/Games/{id}` → 500 | Exception propagated |
+
+---
+
+#### `LibraryClient`
+**File:** `Clients/LibraryClientTests.cs`
+
+| Test | HTTP mock | What it checks |
+|---|---|---|
+| `GetAsync_ReturnsEntityReferences` | GET `/api/Library` → reference list JSON | List deserialized |
+| `AddToLibrary_WithValidGameId_ReturnsTrue` | POST `/api/Library/AddToLibrary/{id}` → `true` | True returned |
+| `RemoveFromLibrary_ById_ReturnsTrue` | POST `/api/Library/RemoveFromLibrary/{id}` → `true` | True returned |
+| `RemoveFromLibrary_WithAddonIds_SendsAddonList` | POST `/api/Library/RemoveFromLibrary/{id}/addons` | Addon IDs in request body |
+
+---
+
+#### `TagClient`
+**File:** `Clients/TagClientTests.cs`
+
+| Test | HTTP mock | What it checks |
+|---|---|---|
+| `CreateAsync_SendsTagAndReturnsCreated` | POST `/api/Tags` → created tag JSON | Returned tag has correct fields |
+| `UpdateAsync_SendsUpdatedTag` | POST `/api/Tags/{id}` → updated tag JSON | Request routed correctly |
+| `DeleteAsync_SendsDeleteRequest` | DELETE `/api/Tags/{id}` → 200 | Delete request sent |
+
+---
+
+#### `PlaySessionClient`
+**File:** `Clients/PlaySessionClientTests.cs`
+
+| Test | HTTP mock | What it checks |
+|---|---|---|
+| `GetAsync_ReturnsSessions` | GET `/api/PlaySessions` → session list JSON | List deserialized |
+| `GetAsync_ByGameId_ReturnsGameSessions` | GET `/api/PlaySessions/{id}` → session list JSON | Filtered sessions returned |
+
+---
+
+#### `ProfileClient`
+**File:** `Clients/ProfileClientTests.cs`
+
+| Test | HTTP mock | What it checks |
+|---|---|---|
+| `GetAsync_ReturnsUser` | GET `/api/Profile` → user JSON | User deserialized |
+| `GetAsync_CalledTwice_UsesCachedResult` | GET `/api/Profile` → 200 (once) | Only one HTTP call made |
+| `GetAsync_WithForceLoad_BypassesCache` | GET `/api/Profile` → 200 (twice) | Two HTTP calls made |
+| `GetAliasAsync_ReturnsAliasFromUser` | GET `/api/Profile` → user JSON | Alias extracted from user object |
+| `ChangeAliasAsync_SendsPutRequest` | PUT `/api/Profile/ChangeAlias` → new alias string | Alias value in response |
+| `GetCustomFieldAsync_ReturnsFieldValue` | GET `/api/Profile/CustomField/{name}` → value string | Value returned |
+| `UpdateCustomFieldAsync_SendsNewValue` | PUT `/api/Profile/CustomField/{name}` → value | Request body matches value |
+
+---
+
+#### `MediaClient` — network methods
+**File:** `Clients/MediaClientTests.cs`
+
+| Test | HTTP mock | What it checks |
+|---|---|---|
+| `GetAsync_ReturnsMediaObject` | GET `/api/Media/{id}` → media JSON | Deserialized correctly |
+| `DownloadAsync_WritesFileToDestination` | GET → binary stream | File exists at destination path |
+| `DownloadAsync_WhenDestinationDirectoryAbsent_CreatesIt` | GET → binary stream | Directory auto-created |
+| `GetStaleLocalPaths_WhenNoFilesExist_ReturnsEmpty` | No HTTP, temp dir | Empty result |
+| `GetStaleLocalPaths_WhenOldVersionsExist_ReturnsThem` | No HTTP, temp dir | Stale files enumerated |
+| `CalculateChecksumAsync_KnownContent_ReturnsDeterministicCrc32` | No HTTP, temp file | Same file → same CRC |
+
+---
+
+#### `IssueClient`
+**File:** `Clients/IssueClientTests.cs`
+
+| Test | HTTP mock | What it checks |
+|---|---|---|
+| `Open_WithValidIssue_ReturnsTrueOnSuccess` | POST `/api/Issue/Open` → `true` | True returned |
+| `Open_WithServerError_ReturnsFalse` | POST `/api/Issue/Open` → 500 | False returned or exception |
+
+---
+
+#### `LauncherClient`
+**File:** `Clients/LauncherClientTests.cs`
+
+| Test | HTTP mock | What it checks |
+|---|---|---|
+| `CheckForUpdateAsync_WhenUpdateAvailable_ReturnsResponse` | GET `/api/Launcher/CheckForUpdate` → JSON | Response deserialized |
+| `DownloadAsync_WritesFileToGivenPath` | GET → binary stream | File written to destination |
+
+---
+
+#### `ConnectionClient` — pure-computation methods
+**File:** `Clients/ConnectionClientTests.cs`
+
+Focus on the methods that do not require a running server:
+
+| Test | Setup | What it checks |
+|---|---|---|
+| `IsConnected_WhenNotYetConnected_ReturnsFalse` | Fresh instance | False by default |
+| `IsConfigured_WhenServerAddressSet_ReturnsTrue` | Mock `ISettingsProvider` with address | True when configured |
+| `IsConfigured_WhenNoAddress_ReturnsFalse` | Mock `ISettingsProvider` with empty address | False without address |
+| `HasServerAddress_WhenAddressSet_ReturnsTrue` | Mock provider | True |
+| `IsOfflineMode_WhenOfflineModeEnabled_ReturnsTrue` | Mock provider offline setting | True |
+| `PingAsync_WithSuccessfulResponse_ReturnsTrue` | HTTP HEAD → custom X-Pong header | True returned |
+| `PingAsync_WithTimeout_ReturnsFalse` | HTTP HEAD → timeout | False returned without throw |
+
+---
+
+#### `SaveClient` — pure-computation methods
+**File:** `Clients/SaveClientTests.cs` *(extend existing file)*
+
+The existing `SaveService.cs` tests cover `GetLocalPath`, `GetArchivePath`, and
+`GetFileSavePathEntries`. The following are the remaining gaps:
+
+| Test | Setup | What it checks |
+|---|---|---|
+| `PackAsync_WithManifestAndSavePaths_ProducesZip` | Temp dir + manifest | Zip contains expected entries |
+| `GetLocalPath_WithInstallDir_ReturnsInstallPath` | No I/O | `{InstallDir}` expanded correctly |
+| `GetLocalPath_WithMyDocuments_ExpandsToActualPath` | No I/O | Special folder expansion |
+| `GetArchivePath_StripsInstallDirPrefix` | No I/O | Archive-relative path returned |
+| `GetFileSavePathEntries_WithDirectorySavePath_ReturnsAllFiles` | Temp dir with files | All files enumerated |
+| `GetFileSavePathEntries_WithRegexSavePath_OnlyMatchingReturned` | Temp dir with mixed files | Non-matching excluded |
+
+---
+
+#### `BeaconClient` — unit-testable subset
+**File:** `Clients/BeaconClientTests.cs`
+
+The UDP broadcast and socket operations require a real network or a UDP socket mock, making
+full integration tests impractical for unit tests. Focus on the fluent API and configuration.
+
+| Test | Setup | What it checks |
+|---|---|---|
+| `AddBeaconMessageInterceptor_ReturnsClientInstance` | No network | Fluent return value |
+| `AddBeaconMessageInterceptor_InterceptorIsCalledOnMessage` | No network, mock interceptor | Interceptor receives message |
+| `CleanupProbe_WhenNotStarted_DoesNotThrow` | No network | Safe on unused instance |
+| `StopProbeAsync_WhenNotRunning_DoesNotThrow` | No network | Safe on unused instance |
+| `StopBeaconAsync_WhenNotRunning_DoesNotThrow` | No network | Safe on unused instance |
+
+---
+
+### Priority 5 — Models with non-trivial logic
+
+---
+
+#### `InstallProgress`
+**File:** `Install/InstallProgressTests.cs` *(already covered, adding edge cases)*
+
+| Test | What it checks |
+|---|---|
+| `Progress_WhenTotalBytesIsZero_ReturnsNaN` | Division by zero → `float.NaN` *(already exists)* |
+| `Progress_WhenBytesExceedTotal_ReturnsGreaterThanOne` | Over-transfer edge case |
+| `Progress_WhenTotalIsNegative_BehavesConsistently` | Negative total |
+
+---
+
+#### `ChatThread`
+**File:** `Models/ChatThreadTests.cs`
+
+`ChatThread` has observable message collections and async event callbacks.
+
+| Test | What it checks |
+|---|---|
+| `AddMessage_IncreasesMessageCount` | Message added to collection |
+| `AddMessage_FiresMessagesReceivedAsync_IfSubscribed` | Callback invoked |
+| `Messages_InitiallyEmpty` | Default state |
+| `Typing_InitiallyEmpty` | Default state for typing indicators |
+
+---
+
+### Priority 6 — `ApiRequestBuilder`
+
+`ApiRequestBuilder` is the common HTTP plumbing used by all clients. Testing it in isolation
+provides coverage of the serialization, header injection, and progress-reporting logic that all
+clients share.
+
+**File:** `Helpers/ApiRequestBuilderTests.cs`
+
+| Test | HTTP mock | What it checks |
+|---|---|---|
+| `GetAsync_SendsGetRequest_ToConfiguredRoute` | Any 200 | Method is GET, URL matches route |
+| `PostAsync_SendsJsonBody` | Capture body, return 200 | Request body deserialized matches input |
+| `PutAsync_SendsJsonBody` | Capture body, return 200 | Method is PUT, body correct |
+| `DeleteAsync_SendsDeleteRequest` | Any 200 | Method is DELETE |
+| `HeadAsync_SendsHeadRequest` | Any 200 | Method is HEAD |
+| `UseAuthenticationToken_AddsAuthorizationHeader` | Capture headers | `Authorization: Bearer <token>` present |
+| `UseVersioning_AddsVersionHeader` | Capture headers | Custom version header present |
+| `AddHeader_AddsCustomHeader` | Capture headers | Header value matches |
+| `SetTimeout_OverridesDefault` | Delayed response | Request cancelled after timeout |
+| `OnProgress_CalledDuringDownload` | Streaming binary | Progress callback fires |
+| `OnComplete_CalledAfterDownload` | Any 200 | Completion callback fires |
+| `SendAsync_On4xx_ThrowsOrReturnsError` | 404 response | Handled consistently |
+| `SendAsync_On5xx_ThrowsOrPropagates` | 500 response | Error propagated |
+| `DownloadAsync_WritesResponseToFile` | Binary stream response | File written at path |
+| `UploadAsync_SendsFileAsMultipart` | Capture request | Content-Type is multipart |
+
+---
+
+## Platform-Specific Tests
+
+Tests that only run on a specific platform should use `Skip` to self-document why they
+are not running rather than silently passing.
+
+```csharp
+[Fact(Skip = "Windows-only: requires P/Invoke to ntdll.dll")]
+public void GetParentProcessId_ReturnsParentPid() { ... }
+```
+
+### Windows-only
+- `RegistryExportUtilityTests` (entire file)
+- `RegistryImportUtilityTests` (entire file)
+- `DisplayHelper.GetDeviceMode()` tests
+- `ProcessHelper.GetParentProcessId()` tests (internal)
+- `LobbyClient.GetSteamLobbies()` — also requires Steam runtime
+
+### Linux-only
+- `DisplayHelper` xrandr/xdpyinfo/drm parsing tests
+
+### Skipped (require real processes or sockets)
+- `ProcessExtensions.WaitForAllExitAsync()` — needs real spawned process, timing-sensitive
+- `BeaconClient.StartProbeAsync()` / `StartBeaconAsync()` — needs real UDP sockets
+
+---
+
+## Pre-existing Issues (do not create new tests for these)
+
+The following failures exist in the test suite and should be addressed in the SDK itself
+before adding further test coverage that would interact with them.
+
+| Area | Root cause |
+|---|---|
+| `SaveDownloadTests` / `SaveUploadTests` | `DeflateEnvironmentVariables` throws on Linux when env vars like `LOCALAPPDATA` are null; `Regex.Escape(null)` throws `ArgumentNullException` |
+| `SaveClientTests.SimpleInstallDirectorySavePathsShouldWork` | Same root cause |
+| `SavePackerTests` (several) | Depends on `GetFileSavePathEntries` which calls `DeflateEnvironmentVariables` |
+| `StringExtensions.cs` (ExpandEnvironmentVariables theory entries) | Tests use Windows-specific paths and env vars; results differ on Linux |
+
+The fix is a null-guard in `StringExtensions.DeflateEnvironmentVariables` before calling
+`Regex.Escape`:
+
+```csharp
+if (string.IsNullOrEmpty(value)) continue;
+```
+
+---
+
+## Implementation Order
+
+1. **Fix the `DeflateEnvironmentVariables` null-guard** — unblocks ~30 currently-failing tests
+2. **`VersionHelper`, `IniHelper` gap-fill** — pure computation, no setup required
+3. **`ApiRequestBuilder` with `FakeHttpMessageHandler`** — builds the HTTP test infrastructure
+4. **Small pure-HTTP clients** (`TagClient`, `PlaySessionClient`, `IssueClient`, `DepotClient`) — simple CRUD, same infrastructure
+5. **`ProfileClient`, `LibraryClient`, `MediaClient`** — moderate complexity
+6. **`AuthenticationClient`** — auth token flow
+7. **`ConnectionClient`** — server health and configuration
+8. **`GameClient`** metadata methods — largest client, split into multiple test files
+9. **`EnvironmentHelper`** with file-system injection
+10. **`DisplayHelper`** parsing extraction + tests
+11. **`RegistryExportUtility` / `RegistryImportUtility`** — Windows CI job