ludic.ui: a new component instance's first build is declared - a first show mid-play is not a frame's keep

Master's windowed fog profile failed the fence at walk t 35 s: +512 B from value_new / value_put /
value_slot / value_lists under bd_class and cmp_keycap_model - a KeyCap first shown mid-walk.

It is a first build, bounded, not a per-show leak: an unmounted instance goes to in_free and the next
show of its class reuses it (in_reuse, `renew`), its props and model objects kept and filled in place.
Only a NEW instance makes them - bounded by how many of that class are up at once, and the ones
unmounted less than two builds ago. in_reuse already declared the record; the props and model objects
and their first fill, made afterwards in bd_class, were not. They are now: in_reuse marks a new record
`fresh`, and bd_class's first fill of it goes through bd_first_fill (@alloc_ok) - a reused instance's
fill stays judged, so a real per-show leak would still fail.

Golden ui_first_show: a component first shown at frame 700, once the fence is judging, then hidden and
shown twice more: bad 0 (the toolchain before this fails frame 701: +464 B value_new from value_slot
under cmp_cell_model, value_put grow - the profile's failure). The 37 ui examples pass.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/ludic.ui/build_class.ludic

@@ -5,17 +5,8 @@ function bd_class(ui_st: mut UiState, k: UiTpl, e: UiEnv, key: string, out: []Ui
   let cls = k.cls
   uc_load(ui_st, cls)
   let it = in_get(ui_st, key, cls)
-  if it.props == null { it.props = Value.object() }
-  let props = it.props
-  Value.clear(props)
-  for i in 0 .. len(k.keys) {
-    let a = k.keys[i]
-    if a != "class" and a != "style" and a != "id" { Value.put(props, a, ui_eval(ui_st, k.vals[i], e)) }
-  }
-  cls.props(it.ptr, props)
   let ce = env_new(ui_st, null)
-  if it.model == null { it.model = Value.object() }
-  ce.model = cls.model(it.ptr, it.model)
+  if it.fresh { ce.model = bd_first_fill(ui_st, it, k, e) } else { ce.model = bd_fill(ui_st, it, k, e) }
   ce.inst = it
   ce.ctx = e.ctx
   ce.slot = k
@@ -34,6 +25,26 @@ function bd_class(ui_st: mut UiState, k: UiTpl, e: UiEnv, key: string, out: []Ui
   bd_kids(ui_st, root, ce, key, out)
   if len(out) > at { bd_pass_down(ui_st, out[at], k, e) }
 }
+# an instance's props and model, filled in place into the objects it keeps (a reused one's are kept)
+function bd_fill(ui_st: mut UiState, it: UiInst, k: UiTpl, e: UiEnv) -> Val {
+  if it.props == null { it.props = Value.object() }
+  let props = it.props
+  Value.clear(props)
+  for i in 0 .. len(k.keys) {
+    let a = k.keys[i]
+    if a != "class" and a != "style" and a != "id" { Value.put(props, a, ui_eval(ui_st, k.vals[i], e)) }
+  }
+  it.cls.props(it.ptr, props)
+  if it.model == null { it.model = Value.object() }
+  return it.cls.model(it.ptr, it.model)
+}
+# a new instance's first fill makes its props and model objects and every Value in them - once per
+# instance, which in_reuse bounds (a prompt's key hint first shown mid-walk was judged as a frame's keep)
+@alloc_ok("a new component instance's first build: its props and model, then kept or reused")
+function bd_first_fill(ui_st: mut UiState, it: UiInst, k: UiTpl, e: UiEnv) -> Val {
+  it.fresh = false
+  return bd_fill(ui_st, it, k, e)
+}
 # <Card class="wide" style="margin: 4px" id="c"> puts those on the card's own root element; when that
 # root is itself a component, each user in turn adds theirs (the outermost's id wins)
 function bd_pass_down(ui_st: mut UiState, n: UiNode, k: UiTpl, e: UiEnv) -> void {

packages/ludic.ui/instance.ludic

@@ -7,6 +7,7 @@ property UiInst {
   seen: int = 0
   props: Val = null             # its props, filled again each frame into the same object
   model: Val = null             # and its model, filled in place by the class's model()
+  fresh: bool = false           # made, not reused: its first build makes its props and model
 }
 # builds before an unmounted instance is mounted again: the tree that last named it is good for two
 const IN_SPARE_AFTER: int = 2
@@ -41,6 +42,7 @@ function in_reuse(ui_st: mut UiState, k: UiClass) -> UiInst {
   let it = new UiInst
   it.cls = k
   it.ptr = k.make()
+  it.fresh = true
   return it
 }
 # after a build of `screen`: its instances the build did not reach are unmounted