Baseline: Ludic compiler + toolchain, Phase 1 syntax fixes complete

Self-hosted compiler (selfhost/*.ludic), runtime, examples, editor tooling,
and docs. Phase 1 of the syntax-redesign cohesion pass has landed:
edge-system fix, signature-query, when-alias, and the documentation truth-pass.
Suite green (14/14), C-free bootstrap fixpoint holds.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

selfhost/emit_ui.ludic

@@ -0,0 +1,125 @@
+# emit_ui.ludic — a `ui` block is data: the compiler flattens the widget tree
+# and emits @ui_build(), which hands every property to the Ludic UI runtime via
+# rt_ui_set(index, key, value). Mirrors compiler/back/ir_ui.c. Layout/drawing/
+# focus all live in runtime/native/ui.ludic.
+
+var uiw: []Node              # flattened widgets, pre-order
+var uiw_parent: []int
+var ui_roots: []int          # first-widget index of each ui block
+
+fn ui_wtype(w: Node) -> int {
+  let s = w.s
+  if streq(s, "panel") { return 0 }  if streq(s, "col") { return 1 }  if streq(s, "row") { return 2 }
+  if streq(s, "label") { return 3 }  if streq(s, "button") { return 4 }
+  if streq(s, "image") { return 5 }  if streq(s, "spacer") { return 6 }
+  return 0
+}
+fn ui_prop(w: Node, key: ptr) -> Node {
+  let i = 0
+  while i < len(w.b.kids) { if streq(w.b.kids[i].s, key) { return w.b.kids[i].a }  i = i + 1 }
+  return ptr_null()
+}
+fn ui_flatten(w: Node, parent: int) -> void {
+  let idx = len(uiw)
+  push(uiw, w)  push(uiw_parent, parent)
+  let i = 0
+  while i < len(w.kids) { ui_flatten(w.kids[i], idx)  i = i + 1 }
+}
+fn ui_flatten_all() -> void {
+  uiw = new []Node  uiw_parent = new []int  ui_roots = new []int
+  let i = 0
+  while i < len(prog) {
+    if prog[i].kind == N_UI and prog[i].ival == 1 { push(ui_roots, len(uiw))  ui_flatten(prog[i].a, 0 - 1) }
+    i = i + 1
+  }
+}
+fn has_ui() -> bool {
+  let i = 0
+  while i < len(prog) { if prog[i].kind == N_UI and prog[i].ival == 1 { return true }  i = i + 1 }
+  return false
+}
+
+# index of a UI_<name>: a ui block's root, or a widget's id=
+fn ui_index_of(nm: ptr) -> int {
+  let s = substr(nm, 3, slen(nm) - 3)          # strip "UI_"
+  let u = 0  let bi = 0
+  let i = 0
+  while i < len(prog) {
+    if prog[i].kind == N_UI and prog[i].ival == 1 { if streq(prog[i].s, s) { return ui_roots[bi] }  bi = bi + 1 }
+    i = i + 1
+  }
+  i = 0
+  while i < len(uiw) {
+    let idp = ui_prop(uiw[i], "id")
+    if not ptr_is_null(idp) { if idp.kind == E_ID and streq(idp.s, s) { return i } }
+    i = i + 1
+  }
+  return 0
+}
+fn is_ui_ident(nm: ptr) -> bool {
+  return slen(nm) > 3 and peek8(nm, 0) == 85 and peek8(nm, 1) == 73 and peek8(nm, 2) == 95   # "UI_"
+}
+
+fn ll_ui_set(idx: int, key: int, val: ptr) -> void {
+  emit("  call void @fn_rt_ui_set(i32 ")  emit(itoa(idx))  emit(", i32 ")  emit(itoa(key))  emit(", i32 ")  emit(val)  emit(")\n")
+}
+fn ui_prop_key(k: ptr) -> int {
+  if streq(k,"w") { return 2 }  if streq(k,"h") { return 3 }  if streq(k,"x") { return 4 }  if streq(k,"y") { return 5 }
+  if streq(k,"pad") { return 7 }  if streq(k,"gap") { return 8 }  if streq(k,"bg") { return 9 }  if streq(k,"fg") { return 10 }
+  if streq(k,"border") { return 11 }  if streq(k,"grow") { return 13 }  if streq(k,"font") { return 14 }  if streq(k,"size") { return 15 }
+  if streq(k,"inset") { return 16 }  if streq(k,"focus") { return 17 }
+  return 0 - 1
+}
+
+fn emit_ui_build() -> void {
+  ui_flatten_all()
+  ll_t = 0  ll_lbl = 0  g_term = false  loc_reset()  nloop = 0
+  let fbody = buf_new()
+  falloc = buf_new()
+  let saved = code
+  code = fbody
+  emit("  call void @fn_rt_ui_reset(i32 ")  emit(itoa(len(uiw)))  emit(")\n")
+  let i = 0
+  while i < len(uiw) {
+    let w = uiw[i]
+    let t = ui_wtype(w)
+    ll_ui_set(i, 0, itoa(t))
+    ll_ui_set(i, 1, itoa(uiw_parent[i]))
+    if t == 4 { ll_ui_set(i, 17, "1") }
+    let p = 0
+    while p < len(w.b.kids) {
+      let pr = w.b.kids[p]
+      let k = pr.s
+      let v = pr.a
+      if streq(k, "id") { p = p + 1  continue }
+      if streq(k, "text") {
+        let sv = emit_expr(v)
+        emit("  call void @fn_rt_ui_static_text(i32 ")  emit(itoa(i))  emit(", ptr ")  emit(sv.code)  emit(")\n")
+      } else { if streq(k, "skin") or streq(k, "image") {
+        let sv = emit_expr(v)
+        let r = emit_bind(sconcat("call i32 @fn_rt_image_load(ptr ", sconcat(sv.code, ")")))
+        if streq(k, "skin") { ll_ui_set(i, 20, r) } else { ll_ui_set(i, 19, r) }
+      } else { if streq(k, "align") {
+        if v.kind == E_ID {
+          let a = 0
+          if streq(v.s, "center") { a = 1 }  if streq(v.s, "end") { a = 2 }
+          ll_ui_set(i, 12, itoa(a))
+        } else { let vv = emit_expr(v)  ll_ui_set(i, 12, vv.code) }
+      } else {
+        let key = ui_prop_key(k)
+        if key >= 0 {
+          let vv = emit_expr(v)
+          ll_ui_set(i, key, vv.code)
+          if key == 4 or key == 5 { ll_ui_set(i, 6, "1") }
+        }
+      } } }
+      p = p + 1
+    }
+    i = i + 1
+  }
+  code = saved
+  emit("define void @ui_build() {\nentry:\n")
+  emit(buf_str(falloc))
+  emit(buf_str(fbody))
+  emit("  ret void\n}\n\n")
+}