Match new Windows workspace naming to macOS

graphcode-windows/README.md

@@ -587,12 +587,45 @@ the new support directory rather than reusing the parent's explicit override.
 The parent's environment and other inherited variables remain unchanged.
 The native New Workspace sheet shows the resolved directory, a separate-window
 diagram titled with the typed name, and workspace-isolation details. Invalid or
-colliding names stay inline with Create & Open disabled; an empty draft stays
-quiet, and Cancel discards it. Ctrl+A selects the complete focused name field
+colliding names stay inline with Create & Open disabled. Only a literal empty
+draft stays quiet; a nonempty whitespace-only draft reports
+"Give the workspace a name — letters and numbers." Cancel discards the draft.
+The diagram trims Foundation `.whitespaces`, including zero-width space, but
+not `.newlines`; trimming affects only the preview, never the raw name passed
+to validation or creation. Ctrl+A selects the complete focused name field
 without changing ordinary typing or AltGr handling. Creation and launch still
-use the existing workspace lifecycle and identity guards. Windows keeps its
-existing ASCII normalization and 48-character limit rather than adopting the
-macOS transliteration and truncation rules.
+use the existing workspace lifecycle and identity guards.
+
+New workspace names follow macOS's operation order: transliterate to Latin,
+strip nonspacing diacritics, lowercase, map characters other than ASCII letters
+and numbers to separators, collapse separators, and take the first 32 characters. The cut
+can end in a hyphen. Preview, submit-time validation, and creation share this
+creation-only rule, including file/directory collisions after transliteration
+or truncation. Windows absolute-path validation and filesystem errors still
+apply; the Darwin socket-path limit does not apply to Windows named pipes.
+Inline collision errors and the submit-to-create race status identify the actual
+creation slug: "A workspace named cafe-zurich already exists." These messages
+own their storage and propagate allocation failures; operational and
+Windows-specific path errors keep their existing failure routes.
+The native implementation uses Windows' built-in ICU C API, loaded only from
+System32 (the combined DLL is available since Windows 10 1903, before the
+Windows 11 baseline and Server 2022/2025 CI hosts). Missing ICU, missing exports,
+or failed transforms report an operational error, never an ASCII fallback.
+The 27 checked naming fixtures were produced by compiling the actual shared
+`Workspace.slug` method with pinned Swift/Foundation 6.3.3. They establish finite
+fixture equivalence, not equality for every Unicode character across OS/ICU
+versions, nor a live native input or paired macOS visual qualification.
+The actual macOS preview method and shared naming-error enum were also compiled
+with that pinned Foundation: 12 preview/validation examples and an exhaustive
+19-scalar `.whitespaces` set agree with the existing `SketchPromotion.trim`
+helper used by this sheet. Headless tests separately retain newlines, refuse
+invalid drafts without creating directories, and cover owned-message and preview
+lifetimes under allocation failure. This does not establish live input, glyph
+rendering, or native dialog qualification.
+Existing directories retain their original names, paths, identities, and
+discovery/activation behavior; nothing is migrated or renamed. Explicit Rename
+keeps its existing ASCII normalization and 48-character limit.
+
 Selecting the current workspace does nothing; selecting an identified running
 workspace restores its exact window rather than the first GraphCode window.
 `Ctrl+Alt+PageUp` / `Ctrl+Alt+PageDown` and Previous/Next Workspace cycle only

graphcode-windows/src/App.zig

@@ -10189,12 +10189,22 @@ pub const App = struct {
         defer result.deinit(self.allocator);
         if (!self.ensureWorkspaceIdentity()) return;
         var workspace = WorkspaceLifecycle.create(self.allocator, result.name, home) catch |err| {
-            self.setStatus(switch (err) {
-                error.EmptyName => "Workspace name is required",
-                error.NameTooLong => "Workspace name is too long",
-                error.NameTaken, error.PathAlreadyExists => "That workspace already exists",
-                else => "Workspace could not be created",
-            });
+            const problem: ?WorkspaceLifecycle.NameError = switch (err) {
+                error.EmptyName => error.EmptyName,
+                error.InvalidName => error.InvalidName,
+                error.NameTooLong => error.NameTooLong,
+                error.NameTaken, error.PathAlreadyExists => error.NameTaken,
+                else => null,
+            };
+            if (problem) |name_problem| {
+                const message = WorkspaceLifecycle.nameProblemMessage(self.allocator, name_problem, result.name) catch |message_error| {
+                    std.log.err("Workspace creation failed ({s}); naming error message failed: {s}", .{ @errorName(err), @errorName(message_error) });
+                    self.setStatus("Workspace name error could not be displayed");
+                    return;
+                };
+                defer self.allocator.free(message);
+                self.setStatus(message);
+            } else self.setStatus("Workspace could not be created");
             return;
         };
         defer workspace.deinit(self.allocator);