typecheck: explain text operands in addition

docs/ADVANCED_STATIC_TYPING.md

@@ -89,7 +89,17 @@ Type mismatch for field backup.score: expected NUMBER, but this value looks like
 
 This remains limited to direct assignments through simple alias chains; control-flow and complex object-flow analysis are still planned.
 
-Text operands are also identified when they appear in subtraction, multiplication, or division expressions. The diagnostic names the operator and the text operand, which catches a common beginner mistake such as subtracting a text field from a number field:
+Text operands are also identified when they appear in arithmetic expressions assigned to NUMBER fields. The diagnostic names the operator and the text operand, which catches a common beginner mistake such as adding a text field to a number field:
+
+```claro
+SET player.score player.name + 1
+```
+
+```text
+Type mismatch for field player.score: addition needs NUMBER values, but player.name looks like TEXT.
+```
+
+Subtraction, multiplication, and division use the same beginner-facing guidance:
 
 ```claro
 SET player.score player.score - player.name

docs/CURRENT_STATUS.md

@@ -57,7 +57,7 @@ Ready now:
 
 Still needed:
 - Keep the focused typecheck validator's fixture list complete as new positive and negative examples are added.
-- The expression checker now carries a known TEXT operand through all arithmetic operators so object-field diagnostics do not hide subtraction, multiplication, or division mistakes; focused numeric-subtraction, numeric-division, and numeric-multiplication positives plus text-operand subtraction, multiplication, and division negatives protect this behavior. Subtraction, multiplication, and division name the text operand and explain that the operator needs NUMBER values.
+- The expression checker now carries a known TEXT operand through all arithmetic operators so object-field diagnostics do not hide addition, subtraction, multiplication, or division mistakes; focused numeric-subtraction, numeric-division, and numeric-multiplication positives plus text-operand addition, subtraction, multiplication, and division negatives protect this behavior. Each operator names the text operand and explains that it needs NUMBER values.
 - richer typed function signatures and return values
 - type checking through branches and loops
 - richer object field type checking beyond simple direct assignments

docs/ROADMAP.md

@@ -36,7 +36,7 @@ See `CURRENT_STATUS.md` for the detailed feature matrix.
 3b. Keep package security validation in Forgejo/Gitea CI so unsafe names, exact manifest-version/name/version/checksum mismatches, missing manifests, duplicate project manifest versions and packages, duplicate lock packages, duplicate package manifest names, versions, and checksums, and lockfile errors remain release blockers.
 4. Add small examples for each foundation feature before adding bigger syntax. The object-field foundation now includes positive and negative validation for field expressions such as `SET player.score player.name`, `SET player.score player.score + 1`, `SET player.name player.score + 1`, explicitly typed field assignments, simple and chained aliases such as `SET alias player`, `SET backup alias`, followed by `SET backup.score ...` or `CHECK TYPE backup.score IS ...`, chained aliases in object-method calls through both modern `DO` and compatibility `CALL ... WITH` forms (including a dedicated positive modern `DO` fixture), and arithmetic/text expression mismatches; typed containers also accept a map with nested type metadata when it is added to a `LIST OF MAP`; broader alias/control-flow checking remains planned.
 5. Keep the focused typecheck validator complete: every `typecheck_*.claro` fixture, including positive fixtures, must be exercised by release validation.
-6. Continue narrowing expression diagnostics: known TEXT operands now remain visible through non-concatenation arithmetic, with focused numeric-subtraction, numeric-division, and numeric-multiplication positives plus text-operand subtraction, multiplication, and division coverage. Subtraction, multiplication, and division give operator-specific guidance naming the text operand.
+6. Continue narrowing expression diagnostics: known TEXT operands now remain visible through arithmetic, with focused numeric-subtraction, numeric-division, and numeric-multiplication positives plus text-operand addition, subtraction, multiplication, and division coverage. Each operator gives specific guidance naming the text operand.
 
 ## Complete-platform milestones