[rupayon123]

Formatting a fully slotted dataclass subclass only enumerates its leaf __slots__, so inherited dataclass fields disappear. A child with no new slots can print as empty despite holding inherited values.

Add missing dataclass field names to the existing no-__dict__ fallback, then retain the leaf slots in their original order. This preserves manually declared auxiliary slots, explicit weakref slots and existing ordering; string-form slot metadata is treated as one name. Classes with an instance __dict__ keep their current behavior. Genuinely absent slot attributes are omitted, so inherited field(init=False, repr=False) values are safe before assignment. Assigned values, including the formatter’s own MISSING object, remain visible.

Validation on CPython 3.13.14 / macOS arm64:

• The final 53 formatter cases reproduce five failures on pristine source and all pass with this change.
• Complete suites pass with extras (162 passed, four existing skips) and without extras (155 passed, 11 existing skips).
• Ruff, strict basedpyright and strict docs pass.
• Public API controls cover multilevel inheritance, overridden fields, empty child slots, manual slot order/auxiliary values, InitVar/ClassVar, dynamic attributes and the unchanged hybrid-class path.

Other supported runtime/OS combinations remain unverified locally. This only changes the existing fully slotted fallback; it does not add previously hidden inherited non-field auxiliary slots.

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Summary by cubic

Fixes formatting of fully slotted dataclass subclasses so inherited fields no longer disappear from pformat() output.

Bug Fixes

• Adds dataclass field names missing from the leaf __slots__ to the no-__dict__ fallback, matching dataclass field ordering.
• Skips slots whose attributes are genuinely unset instead of raising AttributeError.
• Preserves manually declared auxiliary slots and explicit weakref slots; string-form slot metadata is treated as one name.
• Classes with an instance __dict__ keep their current behavior.

^{Written for commit 40698a1. Summary will update on new commits.}

[cubic-dev-ai]

All reported issues were addressed across 2 files

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