ui: GetDebugName, the name an unnamed frame still answers

`Cinematic/Frames.lua:3734` is `entry.name or entry.frame:GetDebugName()` — an addon that keeps a
list of frames reaches for this precisely because some of them have no name, which is the one case
`GetName` cannot serve. With the method absent, `/cine debug frame <name>` raised on the first
unnamed row in the list instead of printing the row the player asked for.

On all three method tables, since the era puts it on ScriptObject. A named frame answers its name,
so a feature test on it learns nothing a 1.12 client would answer differently. The unnamed leg
deviates in its fallback only: it walks the parent's own fields for the key the child is stored
under (frames here are plain tables, so `parent.icon = tex` is visible) and answers
`Parent.<unnamed>` when there is none, where the era answers an index among the parent's children —
an index here would be the order of a list this client does not keep, and a wrong number reads
worse than an honest absence.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SgstFWtn1RxEJ5kVrpgYwn

crates/benilla-ui/src/script/compat/classic_api/frame.rs

@@ -110,6 +110,38 @@ end
 end
 "#;
 
+/// Goes on all three tables: `GetDebugName()` is the era's "what is this frame called" for logs
+/// and error messages, and it answers for an **unnamed** frame too, which `GetName` cannot. An
+/// addon that keeps a list of frames and reports on them reaches for it precisely because some of
+/// them have no name — `Cinematic/Frames.lua:3734` is `entry.name or entry.frame:GetDebugName()`,
+/// and with the method absent its `/cine debug frame <name>` raised on the first unnamed frame in
+/// the list instead of printing the row the player asked for.
+///
+/// Deviation, and it is in the unnamed leg only: the era walks the parent's own fields to find
+/// the key the child is stored under and builds `Parent.key`; failing that it reports an index
+/// among the parent's children. This walks the same fields — frames here are plain tables, so a
+/// `parent.icon = tex` is visible — and falls back to `Parent.<unnamed>` rather than an index,
+/// because an index here would be the creation order of a list this client does not keep and a
+/// *wrong* number reads worse than an honest "no key". A frame with no parent answers
+/// `<unnamed>`.
+const DEBUG_NAME_DELEGATES: &str = r#"
+return function(m)
+function m.GetDebugName(self)
+    local name = self:GetName()
+    if name then return name end
+    local parent = self.GetParent and self:GetParent()
+    if not parent then return "<unnamed>" end
+    local base = parent.GetDebugName and parent:GetDebugName() or parent:GetName() or "<unnamed>"
+    for key, value in pairs(parent) do
+        if value == self and type(key) == "string" then
+            return base .. "." .. key
+        end
+    end
+    return base .. ".<unnamed>"
+end
+end
+"#;
+
 /// Texture-only: `SetColorTexture(r, g, b[, a])` is the modern name for `SetTexture`'s colour arm,
 /// which 1.12 already has (`0x770360` makes the 8x8 solid surface, and our `region/paint.rs` arm
 /// defaults the alpha to 1 exactly as it does). Retail split the two spellings when `SetTexture`
@@ -261,6 +293,7 @@ pub(super) fn install(lua: &Lua) -> mlua::Result<()> {
         delegate(lua, key, GEOMETRY_DELEGATES)?;
         delegate(lua, key, SHOWN_DELEGATES)?;
         delegate(lua, key, MOUSE_OVER_DELEGATES)?;
+        delegate(lua, key, DEBUG_NAME_DELEGATES)?;
     }
     delegate(lua, REG_TEXTURE_METHODS, TEXTURE_DELEGATES)?;
     delegate(lua, REG_FONTSTRING_METHODS, FONTSTRING_DELEGATES)?;

crates/benilla-ui/src/script/tests/widget_surface.rs

@@ -603,6 +603,21 @@ const ALLOWED_BEYOND: &[(&str, &str, &str)] = &[
          addon writes this one — Cinematic/Options.lua:701 paints its list border with it and \
          died at session start without it, and OpenMapClassic its map chrome",
     ),
+    (
+        "GetDebugName",
+        "Button CheckButton ColorSelect DressUpModel EditBox FontString Frame GameTooltip \
+         LootButton MessageFrame Minimap Model MovieFrame ScrollFrame ScrollingMessageFrame \
+         SimpleHTML Slider StatusBar TabardModel Texture WorldFrame PlayerModel",
+        "ClassicAPI: the era's \"what is this frame called\" for a log line or an error message, \
+         and the one that answers for an UNNAMED frame, which GetName cannot. An addon keeping a \
+         list of frames reaches for it precisely because some of them have no name — \
+         Cinematic/Frames.lua:3734 is `entry.name or entry.frame:GetDebugName()`, so /cine debug \
+         frame <name> raised on the first unnamed row instead of printing the one asked for. \
+         Named frames answer their name, so a feature test on it learns nothing a 1.12 client \
+         would answer differently; the unnamed leg deviates in its fallback only (Parent.key by \
+         walking the parent's fields, else Parent.<unnamed>, never the era's child index — a \
+         wrong number reads worse than an honest absence)",
+    ),
     (
         "SetEnabled",
         "Button CheckButton EditBox LootButton",