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llm-ingestion-okf/tests/test_asset_viewable.py
Kjell Tore Guttormsen 579cb1c83c
 refactor(assets,accounting): drop two checks no mutant can fell, add the delta cut 
160 passed over the three affected files. Two guards this round introduced are
removed, each because it was measured and found unkillable, and one real cut is
added in their place.

The end-of-line anchor on the judge's clause expression: with the pointer-block
route and the asset-name tie already in place, the only case it covered is a
label forging a clause inside a block that also carries a real one -- which
`assets._inline` now makes unreachable from a document. Removed with `$` gone
the whole suite stays green, which is the measurement: a guard nothing can fell
is not a guard, and it would also have made the mutant below unfaithful.

The length check on a short absolute run in `_bmp_rle8_rows`: unobservable by
construction. A run shorter than its declared count means the stream ran out,
so the loop cannot reach an end-of-bitmap afterwards and the picture is refused
either way -- the partial paint is discarded with the frame.

A FIFTH CUT REPLACES THEM, and it makes an existing bound load-bearing: a
stream cut in the middle of a delta escape, 17 of 32 pixels wrong by this
file's own decoder. Without the two-byte bound in that branch the cut raises
IndexError instead of a coded refusal.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
2026-09-19 09:36:18 +02:00

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"""Every image a bundle carries must be one a model can actually SHOW.
0.10.0 carried what a document declared, in whatever format the publisher
happened to ship. Measured 2026-09-19 over the frozen R761 delivery's own
`assets/` directory (denominator 50): 29 JPEG, 2 PNG and **19 "PC bitmap,
Windows 3.x, 8-bit, compression 1"** -- RLE8 BMP. The 19 are carried byte for
byte and are correct files; they are also files no model reads, so a figure
the bundle holds is a figure no arm can see. An absence a reader is shown is
information; a picture that is present and unreadable is worse than either,
because the count says it arrived.
THE PROPERTY, and it is a property rather than a list of formats we happen to
have met: for every asset in a built bundle, the format READ OFF ITS BYTES is
in the viewable set. A source image outside that set is converted losslessly
to PNG, or refused with a published code and a line in the concept saying what
stood there. Never carried silently in a format nothing can read.
The viewable set is stated here independently of the package, because a test
that imported the package's own constant would agree with it by construction
and measure nothing. Same for the rejection codes and the pixel grids below:
each guard is pinned against a count or a literal written out in this file, and
the lossless guard decodes through Pillow -- a decoder this package does not
use and does not ship -- so "identical pixels" is not this module agreeing with
itself.
"""
from __future__ import annotations
import hashlib
import io
import struct
import warnings
from pathlib import Path
import pytest
from llm_ingestion_okf import cli, corpus
from llm_ingestion_okf.assets import ASSETS_DIR, read_image, sniff
from llm_ingestion_okf.errors import ExtractionError
BUNDLE_ID = "asset-viewable-fixture"
OKF_VERSION = "0.2"
#: What a model can be shown. Written out here, never imported: the four
#: formats a vision-capable model decodes. A `.bmp`, a `.tiff` and a JPEG 2000
#: codestream are all legitimate image files and none of them is on this list.
VIEWABLE = frozenset({"image/png", "image/jpeg", "image/gif", "image/webp"})
#: The codes this file requires. Stated here so a rename of the package's own
#: constant cannot make these guards pass by agreeing with it.
CODE_NOT_VIEWABLE = "asset_not_viewable"
CODE_TOO_LARGE = "asset_too_large"
# --- fixtures built byte by byte, so the expected pixels are known ----------
#: Four RGB triples. Index 0 is white, which is also what an RLE delta skips
#: over, so the expected grid below states what a skip leaves behind.
PALETTE = bytes((255, 255, 255, 0, 0, 0, 200, 16, 32, 16, 96, 200))
#: An 8x4 image as palette indices, TOP-DOWN. Written out rather than
#: generated: this is the fasit the two decodings are both measured against.
EXPECTED_INDICES = (
(1, 1, 1, 1, 1, 1, 1, 1),
(0, 1, 2, 3, 3, 2, 1, 0),
(3, 3, 3, 0, 0, 1, 1, 1),
(0, 0, 0, 0, 0, 1, 2, 3),
)
#: The same image as an RLE8 opcode stream, BOTTOM-UP as the format requires,
#: exercising all five opcodes: encoded run, absolute run (with its pad byte),
#: delta, end-of-line and end-of-bitmap. A fixture using runs alone would pass
#: with a decoder that never implements the other three.
RLE8_STREAM = bytes(
(
0x05,
0x00,
0x00,
0x03,
0x01,
0x02,
0x03,
0x00,
0x00,
0x00,
0x03,
0x03,
0x00,
0x02,
0x02,
0x00,
0x03,
0x01,
0x00,
0x00,
0x00,
0x08,
0x00,
0x01,
0x02,
0x03,
0x03,
0x02,
0x01,
0x00,
0x00,
0x00,
0x08,
0x01,
0x00,
0x01,
)
)
def expected_rgb() -> bytes:
return b"".join(PALETTE[index * 3 : index * 3 + 3] for row in EXPECTED_INDICES for index in row)
def _dib(width: int, height: int, bits: int, compression: int, body: int, entries: int) -> bytes:
return struct.pack(
"<IiiHHIIiiII", 40, width, height, 1, bits, compression, body, 3779, 3779, entries, entries
)
def _file_header(offbits: int, body: int) -> bytes:
return b"BM" + struct.pack("<IHHI", offbits + body, 0, 0, offbits)
def bmp_rle8(width: int, height: int, palette: bytes, stream: bytes) -> bytes:
"""A Windows 3.x 8-bit RLE8 BMP, the shape 19 of R761's 50 assets have."""
entries = len(palette) // 3
table = b"".join(
bytes((palette[i * 3 + 2], palette[i * 3 + 1], palette[i * 3], 0)) for i in range(entries)
)
offbits = 14 + 40 + len(table)
return (
_file_header(offbits, len(stream))
+ _dib(width, height, 8, 1, len(stream), entries)
+ table
+ stream
)
def bmp_24(rows: tuple[tuple[tuple[int, int, int], ...], ...]) -> bytes:
"""An uncompressed 24-bit BMP -- the other half of the order's fixture."""
height = len(rows)
width = len(rows[0])
pad = b"\x00" * ((-width * 3) % 4)
body = b"".join(
b"".join(bytes((blue, green, red)) for (red, green, blue) in row) + pad
for row in reversed(rows)
)
offbits = 14 + 40
return _file_header(offbits, len(body)) + _dib(width, height, 24, 0, len(body), 0) + body
#: A minimal little-endian TIFF: one IFD with no usable entries. It is a real
#: TIFF by its magic and it is not a format this package can decode with the
#: stdlib, so it is the order's "cannot be converted" case.
TIFF_STUB = b"II\x2a\x00" + struct.pack("<I", 8) + struct.pack("<H", 0) + struct.pack("<I", 0)
RGB_ROWS = (
((255, 0, 0), (0, 255, 0), (0, 0, 255), (255, 255, 0), (0, 0, 0)),
((1, 2, 3), (4, 5, 6), (7, 8, 9), (10, 11, 12), (13, 14, 15)),
((255, 255, 255), (128, 128, 128), (0, 0, 0), (17, 34, 51), (68, 85, 102)),
)
def png_1x1() -> bytes:
"""A real PNG, built with zlib alone -- the already-viewable control."""
import zlib
def chunk(kind: bytes, payload: bytes) -> bytes:
return (
len(payload).to_bytes(4, "big")
+ kind
+ payload
+ zlib.crc32(kind + payload).to_bytes(4, "big")
)
ihdr = struct.pack(">IIBBBBB", 1, 1, 8, 2, 0, 0, 0)
return (
b"\x89PNG\r\n\x1a\n"
+ chunk(b"IHDR", ihdr)
+ chunk(b"IDAT", zlib.compress(b"\x00\x10\x20\x30", 9))
+ chunk(b"IEND", b"")
)
def jpeg_bytes() -> bytes:
"""A real baseline JPEG, encoded by Pillow -- the second viewable control."""
Image = pytest.importorskip("PIL.Image")
buffer = io.BytesIO()
Image.new("RGB", (4, 3), (10, 20, 30)).save(buffer, format="JPEG")
return buffer.getvalue()
def _try_decode(data: bytes) -> tuple[tuple[int, int], bytes] | None:
"""`decode_rgb`, or `None` where the independent decoder cannot read it.
Needed because this guard scans EVERY carried asset, and the point of the
round is that a bundle may hold one nothing can decode. A raised
`UnidentifiedImageError` would make the guard red for the helper's reason
instead of for the claim's.
"""
try:
return decode_rgb(data)
except Exception:
return None
def decode_rgb(data: bytes) -> tuple[tuple[int, int], bytes]:
"""An INDEPENDENT decoding: Pillow, which this package neither uses nor ships."""
Image = pytest.importorskip("PIL.Image")
with Image.open(io.BytesIO(data)) as image:
return image.size, image.convert("RGB").tobytes()
# --- the inbox and the build ------------------------------------------------
def _inbox(root: Path) -> Path:
inbox = root / "inbox"
(inbox / "graphics").mkdir(parents=True)
(inbox / "graphics" / "figur-rle8.bmp").write_bytes(bmp_rle8(8, 4, PALETTE, RLE8_STREAM))
(inbox / "graphics" / "figur-flat.bmp").write_bytes(bmp_24(RGB_ROWS))
(inbox / "graphics" / "skjema.tiff").write_bytes(TIFF_STUB)
(inbox / "prosess.html").write_text(
"<!doctype html>\n<html><head><title>Prosess 84</title></head>\n<body>\n"
"<h1>84 Konstruksjoner av betong</h1>\n"
"<p>Toleranseklassene staar i figuren under.</p>\n"
'<img src="graphics/figur-rle8.bmp" alt="Figur 84-1 Toleranseklasser">\n'
"<p>Og prinsippet:</p>\n"
'<img src="graphics/figur-flat.bmp" alt="Figur 84-2 Prinsipp">\n'
"<p>Og skjemaet:</p>\n"
'<img src="graphics/skjema.tiff" alt="Skjema 84-3">\n'
"</body></html>\n",
encoding="utf-8",
)
return inbox
def _build(inbox: Path, bundle: Path, *extra: str) -> int:
with warnings.catch_warnings():
warnings.simplefilter("ignore")
return cli.main(
[
"build",
str(inbox),
"--bundle",
str(bundle),
"--bundle-id",
BUNDLE_ID,
"--okf-version",
OKF_VERSION,
*extra,
]
)
def _concepts(bundle: Path) -> list[Path]:
return [
path
for path in sorted(bundle.rglob("*.md"))
if path.name not in {"index.md", corpus.LOG_NAME}
]
def _assets(bundle: Path) -> list[Path]:
directory = bundle / ASSETS_DIR
return sorted(p for p in directory.iterdir() if p.is_file()) if directory.is_dir() else []
# --- 1. visibility, as a property of every carried asset --------------------
def test_every_carried_asset_is_a_format_a_model_can_show(tmp_path: Path) -> None:
"""Eval point 1. RED before the conversion: two BMPs are carried as BMP.
The denominator is counted in this test from the inbox itself, so a build
that silently carried nothing would fail here rather than pass over an
empty set -- the failure mode a "0 of 0 violations" assertion cannot see.
"""
pytest.importorskip("llm_ingestion_guard")
inbox = _inbox(tmp_path)
dropped = [p for p in sorted((inbox / "graphics").iterdir()) if p.is_file()]
assert len(dropped) == 3, dropped
not_viewable_in = [p for p in dropped if (sniff(p.read_bytes()) or ("", ""))[0] not in VIEWABLE]
assert len(not_viewable_in) == 3, not_viewable_in
bundle = tmp_path / "bundle"
assert _build(inbox, bundle) == 0
carried = _assets(bundle)
assert carried, "the build carried no asset at all"
offending = [
(path.name, (sniff(path.read_bytes()) or (None,))[0])
for path in carried
if (sniff(path.read_bytes()) or (None,))[0] not in VIEWABLE
]
assert offending == [], (
f"{len(offending)} of {len(carried)} carried assets are in a format no model "
f"can show: {offending}"
)
# --- 2. lossless, against a decoder this package does not use ---------------
def test_the_rle8_source_decodes_to_the_grid_this_file_states() -> None:
"""The fixture's own known-positive: without it, guard 2 could compare two
wrong decodings and agree."""
size, rgb = decode_rgb(bmp_rle8(8, 4, PALETTE, RLE8_STREAM))
assert size == (8, 4)
assert rgb == expected_rgb()
def test_the_carried_png_holds_the_source_pixels_exactly(tmp_path: Path) -> None:
"""Eval point 2. Same RGB per pixel, through the palette, 8x4 = 32 pixels."""
pytest.importorskip("llm_ingestion_guard")
bundle = tmp_path / "bundle"
assert _build(_inbox(tmp_path), bundle) == 0
sources = {
"rle8": bmp_rle8(8, 4, PALETTE, RLE8_STREAM),
"flat24": bmp_24(RGB_ROWS),
}
carried = {path.name: path.read_bytes() for path in _assets(bundle)}
assert len(carried) >= 2, carried
matched = 0
for label, source in sources.items():
source_size, source_rgb = decode_rgb(source)
# VIEWABLE is part of the claim, not decoration: a BMP carried verbatim
# trivially holds its own pixels, so a guard that did not require the
# holder to be viewable would be green before the conversion exists.
hits = [
data
for data in carried.values()
if (sniff(data) or (None,))[0] in VIEWABLE
and _try_decode(data) == (source_size, source_rgb)
]
assert len(hits) == 1, f"{label}: {len(hits)} carried assets hold these pixels"
matched += 1
assert matched == 2
assert len(expected_rgb()) == 8 * 4 * 3
# --- 3. the bundle says what happened ---------------------------------------
def test_the_bundle_records_the_conversion_per_asset(tmp_path: Path) -> None:
"""Eval point 3: original format, original checksum, new checksum."""
pytest.importorskip("llm_ingestion_guard")
bundle = tmp_path / "bundle"
assert _build(_inbox(tmp_path), bundle) == 0
text = "\n".join(path.read_text("utf-8") for path in _concepts(bundle))
sources = (bmp_rle8(8, 4, PALETTE, RLE8_STREAM), bmp_24(RGB_ROWS))
for source in sources:
before = hashlib.sha256(source).hexdigest()
assert before in text, f"the bundle never states the source checksum {before[:12]}"
assert text.count("image/bmp") >= 2, "the bundle never states the original format"
for path in _assets(bundle):
after = hashlib.sha256(path.read_bytes()).hexdigest()
assert path.name.startswith(after[:12]), path.name
converted = [p for p in _assets(bundle) if p.suffix == ".png"]
assert len(converted) == 2, converted
for path in converted:
assert hashlib.sha256(path.read_bytes()).hexdigest() in text
def test_a_converted_asset_is_one_asset_and_not_two(tmp_path: Path) -> None:
"""The accounting's rule: converting is not a second element.
Two BMPs in, two files in `assets/`, two pointers, and the concept's own
`images:` count agreeing with the pointers it holds.
"""
pytest.importorskip("llm_ingestion_guard")
bundle = tmp_path / "bundle"
assert _build(_inbox(tmp_path), bundle) == 0
assert len(_assets(bundle)) == 2, _assets(bundle)
pointers = sum(path.read_text("utf-8").count("](/assets/") for path in _concepts(bundle))
assert pointers == 2, pointers
for path in _concepts(bundle):
body = path.read_text("utf-8")
if "\nimages: " in body:
line = next(row for row in body.splitlines() if row.startswith("images: "))
assert int(line.split(":", 1)[1]) == body.count("](/assets/")
# --- 4. the ceiling is checked before the pixels exist ----------------------
def test_a_bmp_declaring_a_huge_size_is_refused_before_it_is_decoded() -> None:
"""Eval point 4. The bound is on the DECLARATION, paid before the pixels."""
import tracemalloc
# 49 MP, just over the package's 40 MP bound. Deliberately NOT 50 000 x
# 50 000: the guard has to stay able to tell "refused before the decode"
# from "refused after it", and measuring the second costs a frame of the
# declared size. At 7 000 x 7 000 that frame is 49 MB -- affordable to
# measure, and two orders of magnitude over the 4 MB this asserts.
bomb = bmp_rle8(7_000, 7_000, PALETTE, bytes([0xFF, 0x01] * 64))
assert 7_000 * 7_000 > 40_000_000
assert len(bomb) < 4096, len(bomb)
tracemalloc.start()
try:
with pytest.raises(ExtractionError) as caught:
read_image(bomb, name="bombe.bmp")
finally:
_, peak = tracemalloc.get_traced_memory()
tracemalloc.stop()
assert caught.value.code == CODE_TOO_LARGE, caught.value.code
assert peak < 4 * 1024 * 1024, peak
def test_an_rle_stream_longer_than_its_declared_image_costs_the_declaration() -> None:
"""An RLE8 run list that paints far past an 8x4 frame pays for 8x4."""
import tracemalloc
flood = bytes([0xFF, 0x02] * 400_000) + bytes((0x00, 0x01))
bomb = bmp_rle8(8, 4, PALETTE, flood)
assert len(bomb) > 800_000, len(bomb)
tracemalloc.start()
try:
try:
image = read_image(bomb, name="flom.bmp")
except ExtractionError as exc:
code = exc.code
image = None
else:
code = None
finally:
_, peak = tracemalloc.get_traced_memory()
tracemalloc.stop()
if image is not None:
assert sniff(image.data) is not None
assert (sniff(image.data) or (None,))[0] in VIEWABLE
else:
assert code is not None
# The whole file is 800 KB; decoding it must not cost a multiple of that.
assert peak < 16 * 1024 * 1024, peak
def test_a_bmp_whose_name_claims_png_is_still_converted() -> None:
"""The type is read off the BYTES. A rule that trusted the extension would
carry this file unchanged and call it viewable, and every structural check
downstream would agree with it -- the count, the suffix and the pointer.
The R761 delivery is why this is not hypothetical: its graphics directory
holds `.bmp`, `.jpg` and `.png` side by side and the document's own
`xlink:href` values are whatever the publisher's tool wrote.
"""
image = read_image(bmp_rle8(8, 4, PALETTE, RLE8_STREAM), name="graphics/figur.png")
assert image.media_type == "image/png"
assert image.suffix == ".png"
assert decode_rgb(image.data) == ((8, 4), expected_rgb())
# --- 5. the known-positive: what is already viewable does not move ----------
def test_a_png_is_carried_byte_for_byte() -> None:
"""Eval point 5, in-test half. Conversion must reach nothing already viewable."""
data = png_1x1()
image = read_image(data, name="figur.png")
assert image.data == data
assert image.media_type == "image/png"
assert image.suffix == ".png"
def test_a_jpeg_is_carried_byte_for_byte() -> None:
data = jpeg_bytes()
image = read_image(data, name="figur.jpg")
assert image.data == data
assert image.media_type == "image/jpeg"
assert image.suffix == ".jpg"
# --- 6. what cannot be converted is refused out loud ------------------------
def test_a_tiff_is_refused_with_a_published_code() -> None:
"""Eval point 6: never silently carried in a format nothing reads."""
with pytest.raises(ExtractionError) as caught:
read_image(TIFF_STUB, name="skjema.tiff")
assert caught.value.code == CODE_NOT_VIEWABLE, caught.value.code
def test_a_corrupt_bmp_is_refused_with_a_published_code() -> None:
"""A BMP header with a body that stops mid-stream is a refusal, not a guess."""
truncated = bmp_rle8(8, 4, PALETTE, RLE8_STREAM)[:60]
with pytest.raises(ExtractionError) as caught:
read_image(truncated, name="kuttet.bmp")
assert caught.value.code.startswith("asset_"), caught.value.code
def test_the_refused_image_leaves_a_row_the_reader_can_see(tmp_path: Path) -> None:
"""A refusal is a line in the concept and a row in the run log."""
pytest.importorskip("llm_ingestion_guard")
bundle = tmp_path / "bundle"
assert _build(_inbox(tmp_path), bundle) == 0
text = "\n".join(path.read_text("utf-8") for path in _concepts(bundle))
assert "not carried" in text
assert "skjema.tiff" in text
log = (bundle / corpus.LOG_NAME).read_text("utf-8")
assert "image" in log.lower()
# --- 7. a truncated RLE8 stream is refused, never painted -------------------
#: The code the UNCOMPRESSED path already raises for a body that stops short
#: ("refusing to pad, because a short buffer means the header was read wrong").
#: Written out here rather than imported, like the two codes above.
CODE_SAMPLES_INVALID = "asset_samples_invalid"
def rle8_indices(stream: bytes, width: int, height: int) -> bytes:
"""A PERMISSIVE RLE8 decoder, written in this file, top-down.
It paints what the stream holds and leaves the rest at index 0. That is
what the format says about a SKIPPED pixel and what every decoder does
with a stream that simply stops -- which is exactly why a truncation is
invisible without a check: no decoder disagrees, they all agree on the
wrong picture. Its job here is to MEASURE what each cut costs, so the
guard below is pinned to a pixel count this file computed rather than to
the package's opinion of itself.
"""
rows = [bytearray(width) for _ in range(height)]
position, end, x, y = 0, len(stream), 0, 0
while position + 1 < end:
count, value = stream[position], stream[position + 1]
position += 2
if count:
if 0 <= y < height and x < width:
stop = min(x + count, width)
rows[y][x:stop] = bytes((value,)) * (stop - x)
x += count
continue
if value == 0:
x, y = 0, y + 1
elif value == 1:
break
elif value == 2:
if position + 2 > end:
break
x += stream[position]
y += stream[position + 1]
position += 2
else:
run = stream[position : position + value]
position += value + (value & 1)
if 0 <= y < height and x < width:
stop = min(x + len(run), width)
rows[y][x:stop] = run[: stop - x]
x += value
rows.reverse()
return b"".join(bytes(row) for row in rows)
def test_the_cuts_below_land_on_the_opcodes_this_file_names() -> None:
"""The fixture's own known-positive: a cut that no longer truncates
anything would make every guard below pass over nothing."""
assert len(RLE8_STREAM) == 36
assert RLE8_STREAM[32:34] == bytes((0x08, 0x01)), "the last encoded run"
assert RLE8_STREAM[20:22] == bytes((0x00, 0x08)), "the absolute block"
assert RLE8_STREAM[12:16] == bytes((0x00, 0x02, 0x02, 0x00)), "the delta escape"
assert RLE8_STREAM[34:36] == bytes((0x00, 0x01)), "end-of-bitmap"
assert rle8_indices(RLE8_STREAM, 8, 4) == bytes(
index for row in EXPECTED_INDICES for index in row
)
def test_a_truncated_rle8_stream_is_refused_with_a_published_code() -> None:
"""Eval point 6 again, on the one case that was silent.
Measured by PM 2026-09-19 on a real R761 asset (352x548 = 192 896 pixels):
a stream cut to 90 % carried with 13 923 pixels wrong, to 50 % with 95 890,
to 10 % with 166 525 -- no code, no row, a partly blank PNG under a name
that says it holds the source's pixels. The uncompressed path already
refuses the same shape. NO PIXEL MAY BE GUESSED: either every one of them
is decoded from the stream, or the picture is refused.
THE RULE IS THE TERMINATOR, and it is read off the corpus rather than
chosen: over the 19 real RLE8 assets of the frozen R761 delivery, 19 of 19
end at an explicit end-of-bitmap escape, that escape is the stream's LAST
two bytes on 19 of 19, and `biSizeImage` equals the available bytes on
19 of 19. So a stream that runs out before its terminator is refused, and
so is one that is whole but never states it is finished -- the two are the
same bytes from a reader's side, and the measurement says no real writer
here produces the second.
"""
full = rle8_indices(RLE8_STREAM, 8, 4)
cuts = {
"cut in the middle of an encoded run": (RLE8_STREAM[:33], 8),
"cut in the middle of an absolute block": (RLE8_STREAM[:26], 11),
"cut in the middle of a delta escape": (RLE8_STREAM[:14], 17),
"cut immediately before end-of-bitmap": (RLE8_STREAM[:34], 0),
"ends with end-of-line instead of end-of-bitmap": (RLE8_STREAM[:34] + bytes((0, 0)), 0),
}
for label, (stream, lost) in cuts.items():
differ = sum(a != b for a, b in zip(full, rle8_indices(stream, 8, 4)))
assert differ == lost, f"{label}: {differ} pixels differ, this file says {lost}"
with pytest.raises(ExtractionError) as caught:
read_image(bmp_rle8(8, 4, PALETTE, stream), name="kuttet.bmp")
assert caught.value.code == CODE_SAMPLES_INVALID, f"{label}: {caught.value.code}"
# The control: the refusal is about the cut, not about the fixture.
whole = read_image(bmp_rle8(8, 4, PALETTE, RLE8_STREAM), name="hel.bmp")
assert whole.media_type == "image/png"
def test_the_uncompressed_path_refuses_the_same_shape() -> None:
"""The twin this rule was aligned to, so the two BMP paths cannot drift."""
short = bmp_24(RGB_ROWS)[:-30]
with pytest.raises(ExtractionError) as caught:
read_image(short, name="kort.bmp")
assert caught.value.code == CODE_SAMPLES_INVALID, caught.value.code
# --- 8. the lossless guard, with no optional dependency in sight ------------
def png_rgb(data: bytes) -> tuple[tuple[int, int], bytes]:
"""An INDEPENDENT PNG decoding using the stdlib alone: `zlib` and the five
filters of PNG SS 9.2, with the palette applied.
Guard 2 above decodes through Pillow, which this package neither uses nor
ships -- the right independence, and it is an OPTIONAL dependency here
(transitive under `pdfplumber` in `[extract]`). Measured 2026-09-19 on a
core install: 4 of the 13 guards in this file, the lossless one among them,
were SKIPPED, so a plain `pip install llm-ingestion-okf` never measured the
property the round is named after. This arm always runs.
It is independent in the way that matters: the package writes a PNG by
compressing rows it filtered, and this reads one by reversing filters it
decompressed. The expected pixels come from `rle8_indices` and from
`RGB_ROWS`, both written in this file.
"""
import zlib
assert data[:8] == b"\x89PNG\r\n\x1a\n"
position, idat, palette, header = 8, b"", b"", None
while position < len(data):
length = int.from_bytes(data[position : position + 4], "big")
kind = data[position + 4 : position + 8]
payload = data[position + 8 : position + 8 + length]
position += 12 + length
if kind == b"IHDR":
header = struct.unpack(">IIBBBBB", payload)
elif kind == b"PLTE":
palette = payload
elif kind == b"IDAT":
idat += payload
elif kind == b"IEND":
break
assert header is not None
width, height, depth, colour = header[0], header[1], header[2], header[3]
assert depth == 8, depth
channels = {0: 1, 2: 3, 3: 1}[colour]
raw = zlib.decompress(idat)
stride = width * channels
out, previous, at = bytearray(), bytearray(stride), 0
for _ in range(height):
kind_byte = raw[at]
line = bytearray(raw[at + 1 : at + 1 + stride])
at += 1 + stride
for i in range(stride):
left = line[i - channels] if i >= channels else 0
up = previous[i]
upleft = previous[i - channels] if i >= channels else 0
if kind_byte == 1:
line[i] = (line[i] + left) & 0xFF
elif kind_byte == 2:
line[i] = (line[i] + up) & 0xFF
elif kind_byte == 3:
line[i] = (line[i] + (left + up) // 2) & 0xFF
elif kind_byte == 4:
estimate = left + up - upleft
distances = (abs(estimate - left), abs(estimate - up), abs(estimate - upleft))
nearest = (left, up, upleft)[distances.index(min(distances))]
line[i] = (line[i] + nearest) & 0xFF
out += line
previous = line
if colour == 3:
return (width, height), bytes(b for i in out for b in palette[i * 3 : i * 3 + 3])
return (width, height), bytes(out)
def test_the_conversion_is_lossless_measured_with_the_stdlib_alone() -> None:
"""Eval point 2 again, on a path with no optional dependency on either side.
The package encodes a PNG with `zlib`; this decodes one with `zlib` and the
filter definitions, and compares against pixels written out in THIS file.
Pillow appears nowhere, so the guard measures on a core install.
"""
indices = rle8_indices(RLE8_STREAM, 8, 4)
assert indices == bytes(index for row in EXPECTED_INDICES for index in row)
expected = b"".join(PALETTE[index * 3 : index * 3 + 3] for index in indices)
assert expected == expected_rgb()
converted = read_image(bmp_rle8(8, 4, PALETTE, RLE8_STREAM), name="figur-rle8.bmp")
assert converted.media_type == "image/png"
assert png_rgb(converted.data) == ((8, 4), expected)
flat = read_image(bmp_24(RGB_ROWS), name="figur-flat.bmp")
assert flat.media_type == "image/png"
flat_expected = b"".join(bytes(pixel) for row in RGB_ROWS for pixel in row)
assert png_rgb(flat.data) == ((5, 3), flat_expected)
# The negative control: without it, two broken decoders could agree.
assert png_rgb(converted.data)[1] != flat_expected
def test_the_bundle_holds_those_pixels_measured_with_the_stdlib_alone(tmp_path: Path) -> None:
"""The same claim about what the BUILD wrote, not about `read_image`.
Pinned exactly like guard 2 and with no importorskip for Pillow: for each
source, exactly one carried asset decodes to its pixels, and the holder
has to be in the viewable set -- a BMP carried verbatim would hold its own
pixels trivially.
"""
pytest.importorskip("llm_ingestion_guard")
bundle = tmp_path / "bundle"
assert _build(_inbox(tmp_path), bundle) == 0
indices = rle8_indices(RLE8_STREAM, 8, 4)
sources = {
"rle8": ((8, 4), b"".join(PALETTE[i * 3 : i * 3 + 3] for i in indices)),
"flat24": ((5, 3), b"".join(bytes(pixel) for row in RGB_ROWS for pixel in row)),
}
carried = [path.read_bytes() for path in _assets(bundle)]
assert len(carried) == 2, carried
for label, expected in sources.items():
hits = [
data
for data in carried
if (sniff(data) or (None,))[0] in VIEWABLE and png_rgb(data) == expected
]
assert len(hits) == 1, f"{label}: {len(hits)} carried assets hold these pixels"
def test_the_stdlib_arm_runs_with_Pillow_unimportable() -> None:
"""SHOWN, not asserted: the two guards above re-run with `PIL` blocked.
"Runs on a core install" is a claim about an environment, and this file
is usually run in one where `[extract]` -- and therefore Pillow, under
`pdfplumber` -- is installed. So the environment is made here: a finder
that raises for every `PIL` name, with a known-positive proving it fires
before the guards are re-run under it.
"""
import importlib
import sys
class NoPillow:
def find_spec(self, name: str, path: object = None, target: object = None) -> None:
if name == "PIL" or name.startswith("PIL."):
raise ImportError(f"{name} is blocked for this guard")
return None
purged = {name: module for name, module in sys.modules.items() if name.split(".")[0] == "PIL"}
for name in purged:
del sys.modules[name]
sys.meta_path.insert(0, NoPillow())
try:
# KNOWN-POSITIVE: the blocker blocks. Without this the guard below
# would pass in an environment where Pillow was simply present.
with pytest.raises(ImportError):
importlib.import_module("PIL.Image")
test_the_conversion_is_lossless_measured_with_the_stdlib_alone()
indices = rle8_indices(RLE8_STREAM, 8, 4)
expected = b"".join(PALETTE[index * 3 : index * 3 + 3] for index in indices)
assert png_rgb(read_image(bmp_rle8(8, 4, PALETTE, RLE8_STREAM), name="x.bmp").data) == (
(8, 4),
expected,
)
finally:
sys.meta_path.pop(0)
sys.modules.update(purged)
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