feat(migrate): 0.R5 - ludic migrate state --tighten takes mut off every state parameter nothing down the chain writes; --root DIR lets the edits reach a directory without running its programs; a write through a local holding part of a mut state counts as a write to it

Maroon Lake: 149 parameters became read-only. What stays mut is a real write - in the packages mostly a
lazy start inside a question (things_all, gear__ensure), which is what to take out next.

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

selfhost/check/check_state.ludic

@@ -7,15 +7,19 @@
 var ck_ro: []int = new []int            # parallel to ck_names: 1 for a read-only state
 var ck_alias: []Node = new []Node       # parallel to ck_names: the global a local's reference came from
 var ck_ro_st: []pointer = new []pointer # parallel to ck_names: the state that makes a local read-only
+var ck_from_st: []pointer = new []pointer  # parallel to ck_names: the state a local's reference came out of, mut or not
 
 function ck_set_ro(ro: bool) -> void {
   let k = ck_top - 1
   while len(ck_ro) < len(ck_names) { push(ck_ro, 0) }
   while len(ck_alias) < len(ck_names) { push(ck_alias, null) }
   while len(ck_ro_st) < len(ck_names) { push(ck_ro_st, null) }
+  while len(ck_from_st) < len(ck_names) { push(ck_from_st, null) }
   if ro { ck_ro[k] = 1 } else { ck_ro[k] = 0 }
   ck_alias[k] = null
   ck_ro_st[k] = null
+  ck_from_st[k] = null
+  if is_state_ty(ck_tys[k]) { ck_from_st[k] = ck_tys[k] }
   if ro { ck_ro_st[k] = ck_tys[k] }
 }
 # the local just bound is read-only for the same state as local `li`
@@ -42,6 +46,7 @@ function ck_let_from(e: Node, ty: pointer) -> void {
   if li >= 0 and li < k {
     if ck_is_ro(li) { ck_ro_like(li) }
     if li < len(ck_alias) { ck_alias[k] = ck_alias[li] }
+    if li < len(ck_from_st) and k < len(ck_from_st) { ck_from_st[k] = ck_from_st[li] }
     return
   }
   if li >= 0 { return }
@@ -75,6 +80,7 @@ function ck_write_check(t: Node, what: pointer) -> void {
   if li >= 0 {
     mg_local_write(ck_tys[li])                   # 0.S2 --migrate-prune: a state changed here
     if li < len(ck_ro_st) { mg_local_write(ck_ro_st[li]) }
+    if li < len(ck_from_st) and ck_from_st[li] != null { mg_local_write(ck_from_st[li]) }   # through a local holding part of it
     if li < len(ck_alias) and ck_alias[li] != null {
       let ag = ck_alias[li]
       mg_write(t, ag)

selfhost/frontend/migrate.ludic

@@ -19,6 +19,7 @@
 var g_migrate: bool = false
 var g_mg_runtime: bool = false         # --migrate-runtime: the runtime's own vars too
 var g_mg_prune: bool = false           # --migrate-prune: a declared state nothing uses is taken out
+var g_mg_tighten: bool = false         # --migrate-tighten: and a `mut` state nothing down the chain writes is read-only
 var g_ma_node: []Node = new []Node     # each state argument a call passes (an E_ID), its call, its state
 var g_ma_call: []int = new []int
 var g_ma_state: []int = new []int
@@ -602,7 +603,7 @@ function mg_norm_line(line: pointer) -> pointer {
   }
   if len(w) < 2 { return line }
   let k = w[0]
-  if (k == "VAR") or (k == "REF") or (k == "INS") or (k == "LET") or (k == "CLOSE") or (k == "DELITEM") { w[1] = mg_norm(w[1]) }
+  if (k == "VAR") or (k == "REF") or (k == "INS") or (k == "LET") or (k == "CLOSE") or (k == "DELITEM") or (k == "DELMUT") { w[1] = mg_norm(w[1]) }
   if (k == "?") { w[1] = mg_norm(w[1]) }
   if (k == "VAR") and len(w) > 5 { w[5] = mg_norm_key(w[5]) }
   if (k == "STATE") and len(w) > 6 {
@@ -787,6 +788,7 @@ function mg_prune_unit(u: int, n: Node) -> void {
       let p = n.kids[i]
       if p.kind == N_PARAM and is_state_ty(p.ty) and p.pos >= 0 and p.file != null {
         if not has_sub(g_mu_need[u], `,{itoa(mg_state_named(p.ty))},`) { mg_emit(`DELITEM {p.file} {itoa(p.pos)}`, "") }
+        else if g_mg_tighten and p.uns == 1 and p.pos2 >= 0 and not has_sub(g_mu_mut[u], `,{itoa(mg_state_named(p.ty))},`) { mg_emit(`DELMUT {p.file} {itoa(p.pos2)}`, "") }
       }
       i += 1
     }

selfhost/main.ludic

@@ -161,6 +161,10 @@ entry {
       g_allow_globals = true
     }
     else if a == "--migrate-prune" { g_mg_prune = true }     # 0.S2: state parameters nothing uses go too
+    else if a == "--migrate-tighten" {                       # 0.R5: and `mut` goes where nothing down the chain writes
+      g_mg_prune = true
+      g_mg_tighten = true
+    }
     else if a == "--migrate-runtime" { g_mg_runtime = true }   # 0.S: the toolchain's own programs keep module-level vars       # parse, type, module and port checks; nothing emitted
     else if a == "--coverage" { g_coverage = true }
     else if a == "--target" { ai += 1;  if ai < arg_count() { target = arg(ai) } }