phase3: stabilize nullfix.py (disable risky local-nullable handler)

Script stable handlers (zero corruption): bang(!), late, param-nullable,
field-formal field-nullable, arg-bang. Reusable — re-run after manual fixes.
Errors: 2374(peak) -> 596 | web build: 1845 -> 571

lib/pages/blog.dart

@@ -11,7 +11,7 @@ class Blog extends StatelessWidget {
   final Key? key;
   final int businessId;
 
-  const Blog({this.key, int businessId}) :
+  const Blog({this.key, int? businessId}) :
       businessId = businessId ?? Constants.BUSINESS_ID;
 
   @override

lib/pages/edit_address.dart

@@ -16,7 +16,7 @@ class EditAddress extends StatelessWidget {
   final Key? key;
   final Address address;
   final int businessId;
-  const EditAddress(this.address, {this.key, int businessId}) :
+  const EditAddress(this.address, {this.key, int? businessId}) :
       businessId = businessId ?? Constants.BUSINESS_ID;
 
   @override

lib/pages/my_addresses.dart

@@ -11,7 +11,7 @@ class MyAddresses extends StatelessWidget {
   final Key? key;
   final int businessId;
 
-  const MyAddresses({this.key, int businessId}) :
+  const MyAddresses({this.key, int? businessId}) :
       businessId = businessId ?? Constants.BUSINESS_ID;
 
   @override

lib/pages/my_support.dart

@@ -11,7 +11,7 @@ class MySupport extends StatelessWidget {
   final Key? key;
   final int businessId;
 
-  const MySupport({this.key, int businessId}) :
+  const MySupport({this.key, int? businessId}) :
       businessId = businessId ?? Constants.BUSINESS_ID;
 
   @override

lib/pages/new_ticket.dart

@@ -17,7 +17,7 @@ class NewTicket extends StatefulWidget {
   final Key? key;
   final int businessId;
 
-  const NewTicket({this.key, int businessId}) :
+  const NewTicket({this.key, int? businessId}) :
         businessId = businessId ?? Constants.BUSINESS_ID;
 
   @override

lib/widgets/desktop/desktop_edit_address.dart

@@ -23,7 +23,7 @@ class DesktopEditAddress extends StatefulWidget {
   final Key? key;
   final Address address;
   final int businessId;
-  const DesktopEditAddress(this.address, {this.key, int businessId}) :
+  const DesktopEditAddress(this.address, {this.key, int? businessId}) :
       businessId = businessId ?? Constants.BUSINESS_ID;
 
   @override

lib/widgets/desktop/desktop_new_ticket.dart

@@ -21,7 +21,7 @@ class DesktopNewTicket extends StatefulWidget {
   final Key? key;
   final int businessId;
 
-  const DesktopNewTicket({this.key, int businessId}) :
+  const DesktopNewTicket({this.key, int? businessId}) :
         businessId = businessId ?? Constants.BUSINESS_ID;
 
   @override

lib/widgets/mobile/mobile_edit_address.dart

@@ -21,7 +21,7 @@ class MobileEditAddress extends StatefulWidget {
   final Key? key;
   final Address address;
   final int businessId;
-  const MobileEditAddress(this.address, {this.key, int businessId}) :
+  const MobileEditAddress(this.address, {this.key, int? businessId}) :
       businessId = businessId ?? Constants.BUSINESS_ID;
 
   @override

lib/widgets/mobile/mobile_new_ticket.dart

@@ -20,7 +20,7 @@ class MobileNewTicket extends StatefulWidget {
   final Key? key;
   final int businessId;
 
-  const MobileNewTicket({this.key, int businessId}) :
+  const MobileNewTicket({this.key, int? businessId}) :
         businessId = businessId ?? Constants.BUSINESS_ID;
 
   @override

tools/nullfix.py

@@ -33,9 +33,7 @@ PROP = re.compile(r"The property '([^']+)'")
 METH = re.compile(r"The method '([^']+)'")
 OPR  = re.compile(r"The operator '([^']+)'")
 NAME = re.compile(r"'([^']+)'")
-KEYWORDS = {'return','throw','await','yield','break','continue','assert','new','const',
-            'final','var','late','switch','case','default','if','else','for','while',
-            'do','try','catch','finally','in','is','as','super','this'}
+KEYWORDS = {'return','throw','yield','await','break','continue'}
 
 def analyze():
     out = subprocess.run(['dart','analyze','lib'], capture_output=True, text=True).stdout
@@ -101,6 +99,19 @@ def insert_bang(line, col0, name, kind):
         return None
     return None
 
+def make_local_nullable(lines, name, upto_line):
+    """从 upto_line 向上找局部变量声明 'Type name;' 并改可空。"""
+    pat = re.compile(r'^(\s+)(final\s+|const\s+)?(static\s+)?([\w<>?,\s\.]+?)\s+'+re.escape(name)+r'\s*;\s*$')
+    for i in range(upto_line-1, -1, -1):
+        L=lines[i]
+        m=pat.match(L)
+        if not m: continue
+        indent, fmod, smod, typ = m.groups()
+        if typ in ('var',) or '?' in typ or '=' in L: continue
+        return i, f"{indent}{fmod or ''}{smod or ''}{typ}? {name};"
+        break
+    return None, None
+
 def insert_arg_bang(line, col0):
     """在参数值末尾插 '!'（仅限简单值：标识符/成员/调用/下标）。"""
     depth=0; end=None
@@ -195,6 +206,15 @@ def apply_round(errs):
             new=insert_late(old)
         elif rule in ('argument_type_not_assignable','invalid_assignment'):
             new=insert_arg_bang(old, col-1)
+        # not_assigned_potentially_non_nullable_local_variable 不自动处理
+        # （make_local_nullable 易误改 return/throw 语句，风险高，留 IDE）
+        elif False and rule=='not_assigned_potentially_non_nullable_local_variable':
+            nm=NAME.search(msg)
+            if nm:
+                fl=get(path)
+                fi, fnew = make_local_nullable(fl, nm.group(1), line)
+                if fi is not None and fl[fi]!=fnew:
+                    fl[fi]=fnew; changed+=1
         if new and new!=old:
             L[line-1]=new; changed+=1
     flush()