refactor: Parquet class accepts pre-loaded data instead of reading from disk

[boscorat]

Parent issue

#194 — function purification

Problem

Parquet.__init__ (parquet.py:49) reads an existing parquet file from disk during construction (line 56), and deletes the file if the column layout mismatches (line 60). This means you cannot create a Parquet instance without a real file on disk.

Similarly, Parquet.create() (line 70), Parquet.update() (line 77), and Parquet.delete() (line 83) all write to disk as their primary action.

Proposal

Accept an optional pre-loaded DataFrame in the constructor instead of reading from disk. Move file I/O to a @classmethod from_file(cls, path) factory. Return DataFrames from create/update/delete and let the caller handle writing.

Code relationships

Target class:

• Parquet — parquet.py:49

Subclasses (will inherit changes):

• ChecksAndBalances — parquet.py
• StatementHeads — parquet.py
• StatementLines — parquet.py
• BatchHeads — parquet.py
• BatchLines — parquet.py

Callers (will need updating):

• update_parquet() — parquet.py:673
• process_pdf_statement() — statements.py:828 (creates BatchLines, StatementHeads, etc.)
• update_db() — database.py:387 (reads temp parquet files)

Existing tests

None. No direct tests exist for any Parquet class. Refactoring will not break any existing tests.

Siblings

• refactor: BatchMetadata dataclass to replace 13 duplicated parameters #195 — BatchMetadata dataclass
• refactor: ExtractionContext dataclass for extraction pipeline #196 — ExtractionContext dataclass
• refactor: decompose Statement constructor into pure factory + persistence #197 — Statement constructor decomposition
• refactor: decompose process_pdf_statement into pure extraction + persistence #198 — process_pdf_statement decomposition
• refactor: stop mutating inputs in extraction pipeline #199 — Stop mutating inputs
• refactor: add optional conn parameter to build_datamart and related functions #200 — DB connection threading
• refactor: move processing out of StatementBatch constructor #201 — StatementBatch constructor
• refactor: remove dead logs and file_path parameters from pipeline functions #202 — Dead parameter cleanup
• refactor: _handle_parquet_write_error returns error dict instead of mutating #204 — _handle_parquet_write_error purification