Fix non-idempotent black-profile output for name-level import comments

isort/output.py

@@ -723,15 +723,35 @@ def _with_from_imports_for_module(
                 parsed.categorized_comments["nested"].setdefault(module, {})[from_import] = comment
                 continue
             if comment is not None:
-                # If the comment is a noqa and hanging indent wrapping is used,
-                # keep the name in the main list and hoist the comment to the statement.
-                if (
+                # If the comment would land on the opening-paren line after wrapping
+                # (hanging-indent noqa, or any comment in the vertical modes that
+                # hoist via wrap._hoist_comment_to_paren), keep the name in the main
+                # list and hoist the comment to the statement. Otherwise the name is
+                # split onto its own statement, wrap.line may hoist the comment to a
+                # statement-level position, and the next run regroups — non-idempotent
+                # under black profile (see #2694).
+                vertical_modes = (
+                    wrap_modes.WrapModes.VERTICAL_HANGING_INDENT,
+                    wrap_modes.WrapModes.VERTICAL_GRID_GROUPED,
+                )
+                hoist_to_statement = (
                     comment.lower().startswith("noqa")
                     and config.multi_line_output == wrap_modes.WrapModes.HANGING_INDENT
-                ):
-                    comments = list(comments) if comments else []
-                    comments.append(comment)
-                    continue
+                ) or config.multi_line_output in vertical_modes
+                if hoist_to_statement:
+                    # Only hoist when a standalone name+comment line would not fit;
+                    # short lines can keep the name-level comment without churn.
+                    standalone = (
+                        f"{import_start}{from_import}"
+                        f"{config.comment_prefix} {comment}"
+                    )
+                    if (
+                        config.multi_line_output == wrap_modes.WrapModes.HANGING_INDENT
+                        or len(standalone) > config.line_length
+                    ):
+                        comments = list(comments) if comments else []
+                        comments.append(comment)
+                        continue
 
                 from_imports.remove(from_import)
                 if from_imports:

tests/unit/test_ticketed_features.py

@@ -1264,3 +1264,36 @@ def test_comment_not_duplicated_across_from_imports_2282() -> None:
 from foo import e
 """
     assert isort.code(code) == code
+
+
+def test_nested_import_comment_idempotent_under_black_profile_2694() -> None:
+    """A name-level inline comment must not make black-profile output non-idempotent.
+
+    When a deeply-dotted from-import carries a per-name comment that does not fit
+    on one line, isort used to split that name onto its own statement. The next
+    run then regrouped remaining names differently (or hoisted the comment), so
+    ``isort --check`` rejected isort's own first-pass output. See #2694.
+    """
+    source = (
+        "from pkg.submodule.submodule.submodule.submodule import (\n"
+        "    alpha,  # type: ignore[import-untyped]\n"
+        "    beta, gamma\n"
+        ")\n"
+    )
+    first = isort.code(source, profile="black")
+    second = isort.code(first, profile="black")
+    assert first == second
+    assert isort.check_code(first, profile="black")
+    assert first == (
+        "from pkg.submodule.submodule.submodule.submodule import ("
+        "  # type: ignore[import-untyped]\n"
+        "    alpha,\n"
+        "    beta,\n"
+        "    gamma,\n"
+        ")\n"
+    )
+
+    # Short module paths keep the name-level comment (no hoist needed).
+    short = "from pkg import alpha  # type: ignore\n"
+    assert isort.code(short, profile="black") == short
+    assert isort.code(isort.code(short, profile="black"), profile="black") == short