A Restore whose ThemeFile fails to load changes no theme: the session goes on showing the one it did, its file still the one named

A Restore makes a fresh core, which started at the default theme and
asked for the dump's ThemeFile; when that file had broken since, the
failure reverted to what the fresh core had loaded, nothing, and ink
became orchard. A Restore that asks for a ThemeFile now carries over
the theme the old session showed and the file it loaded (and its Theme,
unless the dump names one), so a failure there changes nothing.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

3 files changed, 29 insertions, 0 deletions

diff --git a/src/colors.zig b/src/colors.zig
index a45184c8..2dcb906a 100644
--- a/src/colors.zig
+++ b/src/colors.zig
@@ -837,6 +837,19 @@ pub fn loadThemeFile(p: *Pardes, generation: u32, bytes: []const u8, animate: bo
     return true;
 }
 
+/// A Restore's: the theme `old` showed, its loaded theme file's included,
+/// for one that is to load a ThemeFile and keep this if it fails;
+/// `index` too when the dump names no Theme.
+pub fn carryTheme(p: *Pardes, old: *const Pardes, index: bool) !void {
+    if (index) p.settings.theme = old.settings.theme;
+    const t = old.custom_theme orelse return;
+    var copy = t;
+    copy.name = try p.gpa.dupe(u8, t.name);
+    if (p.custom_theme) |mine| std.zon.parse.free(p.gpa, mine);
+    p.custom_theme = copy;
+    _ = p.theme_file_loaded.set(old.theme_file_loaded.get());
+}
+
 pub fn finishThemeInitialization(p: *Pardes) void {
     p.chrome_animation.snap(ChromeTheme.fromTheme(p.theme()));
     p.animate_theme_changes = true;
diff --git a/src/dump.zig b/src/dump.zig
index e76bb1a2..fa21eaa4 100644
--- a/src/dump.zig
+++ b/src/dump.zig
@@ -888,6 +888,16 @@ fn initDump(gpa: std.mem.Allocator, opts: Options, zon_bytes: []const u8, previo
     p.locations_config = st.locations_config;
     p.settings.tree_context_tag_style = st.tree_context_tag_style;
     applySettings(p, st.settings);
+    // A dump naming a ThemeFile asks the host to load it again: until it
+    // has, and for good if it fails, the theme this session showed goes on
+    // (a failed ThemeFile changes nothing, a Restore's included), unless
+    // the dump names a Theme of its own.
+    if (previous) |old| if (p.theme_file_path.get().len > 0) {
+        const names_theme = for (st.settings) |line| {
+            if (std.mem.startsWith(u8, line, "Theme ")) break true;
+        } else false;
+        try colors.carryTheme(p, old, !names_theme);
+    };
     for (st.mounts) |mount| {
         var already_mounted = false;
         for (p.fs.mounts.items) |existing| {
diff --git a/src/ninep/ctl.zig b/src/ninep/ctl.zig
index b7c529e1..a5a36464 100644
--- a/src/ninep/ctl.zig
+++ b/src/ninep/ctl.zig
@@ -2102,6 +2102,12 @@ test "a Restore asks again for the ThemeFile the dump names, as a /ctl write of
         else => {},
     } else return error.NoThemeFileAsked;
     try testing.expectEqualStrings(good, pardes.colors.themeFileRequest(restored, asked.generation).?.path);
+    // The file broken since, the load fails: the restored session still
+    // shows the theme the old one did, and names the file it loaded.
+    try testing.expectEqualStrings("restored", restored.theme().name);
+    pardes.colors.failThemeFile(restored, asked.generation, error.ParseZon);
+    try testing.expectEqualStrings("restored", restored.theme().name);
+    try testing.expectEqualStrings(good, restored.theme_file_path.get());
 }
 
 test "a ThemeFile that fails to load changes nothing: the root ctl still names the one loaded, or none" {