fix: preserve from_body comments on force_single_line and combine_star

Route comment-only members onto the first single-line import and fold
them into combine_star star comments so #1852 does not silently drop
body comments on secondary emit paths.

Fixes residual findings from multi-stage review on #2588.

Signed-off-by: Alex Chen <l46983284@gmail.com>

Author: l46983284-cpu

isort/output.py

@@ -400,9 +400,14 @@ def _with_from_imports(
                 above_comments = None
 
             if "*" in from_imports and config.combine_star:
+                # Fold from_body comments onto the star statement (main-compatible).
+                star_comments = list(comments or ())
+                if body_comments and not config.ignore_comments:
+                    star_comments = star_comments + body_comments
+                    body_comments = []
                 import_statement = wrap.line(
                     with_comments(
-                        _with_star_comments(parsed, module, list(comments or ())),
+                        _with_star_comments(parsed, module, star_comments),
                         f"{import_start}*",
                         removed=config.ignore_comments,
                         comment_prefix=config.comment_prefix,
@@ -416,6 +421,11 @@ def _with_from_imports(
                 only_show_as_imports = True
             elif config.force_single_line and module not in config.single_line_exclusions:
                 import_statement = ""
+                # Preserve comment-only members on the first single-line import
+                # (matches pre-#1852 main behaviour for force_single_line).
+                if body_comments and not config.ignore_comments:
+                    comments = list(comments or []) + body_comments
+                    body_comments = []
                 while from_imports:
                     from_import = from_imports.pop(0)
                     single_import_line = with_comments(

tests/unit/test_regressions.py

@@ -2430,3 +2430,26 @@ def test_comment_only_lines_in_from_import_group_issue_1852():
     mixed_out = isort.code(mixed, profile="black")
     assert mixed_out == mixed_expected
     assert isort.code(mixed_out, profile="black") == mixed_out
+
+
+def test_force_single_line_preserves_body_comments_issue_1852():
+    """force_single_line must not drop comment-only from-import members.
+
+    Regression against silent loss after from_body routing (issue #1852).
+    """
+    mixed = "from foo import (\n    zeta,\n    # disabled\n    alpha,\n)\n"
+    out = isort.code(mixed, profile="black", force_single_line=True)
+    assert "# disabled" in out
+    assert "from foo import alpha" in out
+    assert "from foo import zeta" in out
+    # main-compatible: comment attached to first emitted line
+    assert "from foo import alpha  # disabled" in out
+    assert isort.code(out, profile="black", force_single_line=True) == out
+
+
+def test_combine_star_folds_body_comments_issue_1852():
+    """combine_star should fold body comments onto the star statement."""
+    src = "from foo import (\n    # disabled\n    *\n)\n"
+    out = isort.code(src, combine_star=True)
+    assert out == "from foo import *  # disabled\n"
+    assert isort.code(out, combine_star=True) == out