Refactor/lazy parsing remove sentinel in parser

src/fasteit/parsers/draeger/bin/bin_parser.py

@@ -12,11 +12,8 @@
 from fasteit.parsers.errors import AmbiguousFormatError, UnsupportedFrameSizeError
 
 from .bin_utils import (
-    _BIT_SENTINELS,
-    _FLOAT_SENTINELS,
     estimate_sampling_frequency_hz,
     normalize_frame_slice,
-    replace_no_data_sentinels,
 )
 
 # Default sampling frequency used when fs cannot be estimated from timestamps.
@@ -43,10 +40,6 @@ class DragerBinParser(BaseParser):
       https://github.com/EIT-ALIVE/eitprocessing
     """
 
-    def __init__(self) -> None:
-        self._float_sentinels = _FLOAT_SENTINELS
-        self._bit_sentinels = _BIT_SENTINELS
-
     def validate(self, path: Path) -> bool:
         """Return True if file exists, is non-empty, and has a known frame size."""
         path = Path(path)
@@ -119,35 +112,17 @@ def parse(
         else:
             warnings_list = []
 
-        # ── 6. Copy memmap to writable array ──────────────────────────────────
-        frames = mapped_frames.copy()
-
-        # ── 7. Sanitize pixels: vectorized over all frames at once ────────────
-        frames["pixels"] = replace_no_data_sentinels(
-            mapped_frames["pixels"],
-            self._float_sentinels,
-            self._bit_sentinels,
-        )
-
-        # ── 8. Sanitize Medibus data if present (EXT format only) ─────────────
-        if spec.medibus_fields is not None:
-            frames["medibus_data"] = replace_no_data_sentinels(
-                frames["medibus_data"],
-                self._float_sentinels,
-                self._bit_sentinels,
-            )
-
-        # ── 9. Build aux_signals dict: {signal_name → array shape (N,)} ──────
+        # ── 6. Build aux_signals dict: {signal_name → array shape (N,)} ──────
         aux_signals = None
         if spec.medibus_fields is not None:
             aux_signals = {
-                field_name: frames["medibus_data"][:, field_idx]
+                field_name: mapped_frames["medibus_data"][:, field_idx]
                 for field_idx, field_name in enumerate(spec.medibus_fields)
             }
 
         # ── 10. Assemble and return result ────────────────────────────────────
         result = ReconstructedFrameData(
-            frames=frames,
+            frames=mapped_frames,
             aux_signals=aux_signals,
             fs=fs,
             filename=str(path),

tests/test_bin_parser.py

@@ -125,7 +125,12 @@ def test_parse_slice_max_frames(tmp_path):
 # ── float sentinel replacement ────────────────────────────────────────────────
 
 
-def test_parse_float_sentinel_replaced_with_nan(tmp_path):
+def test_parse_float_sentinel_preserved_in_raw_data(tmp_path):
+    """Parser returns raw memmap — sentinel values are NOT replaced.
+
+    Sentinel replacement is deferred to the preprocessing layer so that
+    the memmap is never copied to RAM during parsing (lazy loading).
+    """
     frames = np.zeros(3, dtype=FRAME_BASE_DTYPE)
     dt_day = 1.0 / (50.0 * 86400.0)
     frames["ts"] = np.arange(3) * dt_day
@@ -134,12 +139,10 @@ def test_parse_float_sentinel_replaced_with_nan(tmp_path):
     frames.tofile(path)
 
     data = DragerBinParser().parse(path)
-    assert np.isnan(data.pixels[1, 0, 0])
+    assert data.pixels[1, 0, 0] == -1000.0
 
 
 # ── Round-trip value correctness (Tasks 1.5.3 / 1.5.4 / 1.5.5 / 1.5.10) ─────
-# Uses the shared bin_3frames fixture from conftest.py.
-# Frame i has all pixels = float(i+1), timestamps at 50 Hz fraction-of-day.
 
 _DT_DAY = 1.0 / (50.0 * 86400.0)