Move the page to /word-addin: the deploy already owns /word

README.md

@@ -303,7 +303,7 @@ A tool that answers everything is easy to build. This is the other kind.
 
 ### Installing it
 
-**[The add-in's page →](https://peopleworks.github.io/SignsofAI/word)** — what it does, both
+**[The add-in's page →](https://peopleworks.github.io/SignsofAI/word-addin)** — what it does, both
 install routes, and what it refuses to do, in English and Spanish.
 
 The short version: on the web it is Home → Add-ins → More Add-ins → My Add-ins → **Upload My Add-in**

src/SignsOfAI.UI/Layout/MainLayout.razor

@@ -24,7 +24,7 @@
             <NavLink class="nav-link" href="catalog">@L["nav.catalog"]</NavLink>
             @* No host condition, unlike the two below: somebody using the desktop app writes in
                Word too, and the add-in is useful to them for the same reasons. *@
-            <NavLink class="nav-link" href="word">@L["nav.word"]</NavLink>
+            <NavLink class="nav-link" href="word-addin">@L["nav.word"]</NavLink>
             @* Only where there is something to gain by downloading it. The same signal as the
                folder link above, and for the same reason: this host cannot open a folder, so a
                better host exists for this machine and hiding that would be the lowest-common-

src/SignsOfAI.UI/Pages/Download.razor

@@ -113,7 +113,7 @@ else
     <h2 class="dl-h2"><Icon Name="file-text" /> @L["dl.word.title"]</h2>
     <p class="hint">@L["dl.word.lede"]</p>
     <div class="cta">
-        <a class="primary" href="word">@L["dl.word.page"]</a>
+        <a class="primary" href="word-addin">@L["dl.word.page"]</a>
     </div>
 </section>
 

src/SignsOfAI.UI/Pages/WordAddin.razor

@@ -1,4 +1,7 @@
-@page "/word"
+@* /word-addin, not /word: the deploy publishes the task pane itself at /word/, and a directory
+   on the host wins over a route in the router. The pane's address is in a manifest people have
+   already installed, so the pane keeps it and the page moves. *@
+@page "/word-addin"
 @using SignsOfAI.Core.Calibration
 @inherits LocalizedComponent
 

tests/SignsOfAI.Core.Tests/DeployedPathTests.cs

@@ -0,0 +1,90 @@
+using System.Text.RegularExpressions;
+using Xunit;
+
+namespace SignsOfAI.Core.Tests;
+
+/// <summary>
+/// The deploy publishes two applications onto one host: the web app at the site root, and the Word
+/// task pane in a subdirectory of it. A real directory beats a client-side route, so any page whose
+/// <c>@page</c> path matches that subdirectory is unreachable — the visitor gets the task pane,
+/// which outside Word says it has no document to read.
+///
+/// That happened. <c>/word</c> was given to a page while the deploy was already publishing the pane
+/// at <c>/word/</c>, and the navigation link led to the pane for as long as it took to notice. It is
+/// invisible locally, because a dev server has neither directory, and invisible in the diff, because
+/// the two halves live in different files.
+/// </summary>
+public class DeployedPathTests
+{
+    private static string RepoRoot()
+    {
+        var dir = new DirectoryInfo(AppContext.BaseDirectory);
+        while (dir is not null && !Directory.Exists(Path.Combine(dir.FullName, "src")))
+            dir = dir.Parent;
+
+        Assert.NotNull(dir);
+        return dir!.FullName;
+    }
+
+    /// <summary>Every route the router owns, from the <c>@page</c> directives themselves.</summary>
+    private static IReadOnlyList<string> Routes()
+    {
+        string pages = Path.Combine(RepoRoot(), "src", "SignsOfAI.UI", "Pages");
+        var routes = new List<string>();
+
+        foreach (string file in Directory.EnumerateFiles(pages, "*.razor"))
+            foreach (Match m in Regex.Matches(File.ReadAllText(file), @"^@page\s+""/([^""]*)""", RegexOptions.Multiline))
+                routes.Add(m.Groups[1].Value.Trim('/'));
+
+        Assert.NotEmpty(routes);
+        return routes;
+    }
+
+    /// <summary>
+    /// The directory the deploy copies the pane into, taken from the workflow rather than repeated
+    /// here — the point of this test is that the two are compared, not that both are typed twice.
+    /// </summary>
+    private static string PaneDirectory()
+    {
+        string workflow = File.ReadAllText(
+            Path.Combine(RepoRoot(), ".github", "workflows", "deploy-pages.yml"));
+
+        var m = Regex.Match(workflow, @"cp -r publish-word/wwwroot publish/wwwroot/(\S+)");
+        Assert.True(m.Success,
+            "deploy-pages.yml no longer copies the task pane where this test expects. If the step " +
+            "moved or was renamed, update this pattern — do not delete the check.");
+
+        return m.Groups[1].Value.Trim('/');
+    }
+
+    [Fact]
+    public void No_page_route_is_shadowed_by_the_task_pane_directory()
+    {
+        string pane = PaneDirectory();
+        var clash = Routes().FirstOrDefault(r => string.Equals(r, pane, StringComparison.OrdinalIgnoreCase));
+
+        Assert.True(clash is null,
+            $"A page is routed at \"/{clash}\" and the deploy publishes the task pane at \"/{pane}/\". " +
+            "On the host the directory wins and the page is unreachable — visitors get the pane. " +
+            "Move the page's route; the pane's address is in a manifest people have installed.");
+    }
+
+    [Fact]
+    public void The_manifest_points_at_the_directory_the_deploy_publishes()
+    {
+        // The other half of the same seam: the pane's URL lives in the manifest Word loads, and the
+        // deploy decides where the files land. If those two disagree the add-in 404s, which Word
+        // reports as "this add-in may not load properly" — an error a long way from its cause.
+        string manifest = File.ReadAllText(
+            Path.Combine(RepoRoot(), "src", "SignsOfAI.Word", "manifest.xml"));
+
+        var source = Regex.Match(manifest, @"<SourceLocation DefaultValue=""([^""]+)""");
+        Assert.True(source.Success, "The manifest has no SourceLocation.");
+
+        string path = new Uri(source.Groups[1].Value).AbsolutePath;   // /SignsofAI/word/index.html
+        string[] parts = path.Trim('/').Split('/');
+
+        Assert.True(parts.Length >= 2, $"SourceLocation \"{path}\" has no subdirectory to compare.");
+        Assert.Equal(PaneDirectory(), parts[^2]);
+    }
+}