[1.5.2] - 2026-04-19

Added

• Parse Cache (engine/parse_cache.py): mtime-based file extraction cache.
  Algorithm absorbed from RAG-Anything processor.py:_generate_cache_key().
  Cache key = MD5(resolved_path + mtime + parser_config). Path-indexed reverse
  map enables O(1) invalidate(). API: get/put/invalidate/clear/stats.
  extract_text(use_cache=True) integrates transparently — no API change.
  Score: 0.0 CLEAN.

• ContextExtractor (engine/context_extractor.py): Sliding-window chunk
  context extractor for RAG result enrichment. Algorithm absorbed from
  RAG-Anything modalprocessors.py:ContextExtractor. Given chunk_text()
  output, enrich_chunks() adds a context key to each chunk containing
  surrounding neighbour text. ContextConfig: window_size, max_context_chars,
  include_headings. Zero external dependencies. Score: 0.0 CLEAN.

• Backend Plugin Architecture (engine/format_backends.py): Format-family
  backends absorbed from Docling abstract_backend.py pattern.
  AbstractFormatBackend ABC with supported_extensions + extract().
  BackendRegistry maps extensions to backend classes; new formats register
  without modifying the dispatcher. 11 concrete backends:
  PDFBackend, DOCXBackend, DOCBackend, XLSXBackend, PPTXBackend,
  RTFBackend, HTMLBackend, VTTBackend, LaTeXBackend, CSVBackend,
  ImageBackend, PlainTextBackend. Score: 12.2 clean.

Refactored

• engine/file_parser.py (75 lines, was 340): Rewritten as pure registry
  dispatcher — _dispatch() resolves backend via BackendRegistry.get(ext)
  then calls backend.extract(). Cyclomatic complexity 13 → 3.
  function_clone_cluster (5 structurally similar _extract_* functions)
  eliminated by moving each into its own Backend class. Score: 3.0 CLEAN.

Tests

• tests/test_phase1_parse_cache_context.py: 33 tests (parse_cache + ContextExtractor).
• tests/test_phase2_format_backends.py: 50 tests (registry + backends + helpers).
• Combined: 83 tests, all passing. AI-Slop-Detector critical deficits: 0.