feat(scenegraph): add ImageHashPipeline protocol and update query API

- Introduce ImageHashPipeline Protocol for extensible hash computation
- Rename query_crop_index to query_index for clarity
- Make query_crop nullable to handle missing crop edge case
- Add keyword-only arguments for better API clarity
- Handle empty scene graph objects gracefully
- Add comprehensive test coverage for query_image_against_scene_graph

mini-nav/scenegraph/__init__.py

@@ -2,7 +2,7 @@
 
 This module exports the main scenegraph objects for easy import:
 
-from mini_nav.scenegraph import SimpleSceneGraph, RoomNode, ObjectNode
+from scenegraph import SimpleSceneGraph, RoomNode, ObjectNode
 """
 
 from .hash_codec import (
@@ -13,13 +13,18 @@ from .hash_codec import (
     hash_bytes_to_cam_row,
 )
 from .objectnode import ObjectNode
-from .query import ImageSceneGraphQueryResult, query_image_against_scene_graph
+from .query import (
+    ImageHashPipeline,
+    ImageSceneGraphQueryResult,
+    query_image_against_scene_graph,
+)
 from .roomnode import RoomNode
 from .scenegraph import SceneGraphMatch, SimpleSceneGraph
 from .software_cam import CamMatch, SoftwareCamIndex, xnor_popcount_score
 
 __all__ = [
     "CamMatch",
+    "ImageHashPipeline",
     "ImageSceneGraphQueryResult",
     "ObjectNode",
     "RoomNode",

mini-nav/scenegraph/query.py

@@ -1,7 +1,7 @@
 from __future__ import annotations
 
 from dataclasses import dataclass
-from typing import Any
+from typing import Any, Protocol, runtime_checkable
 
 from PIL import Image
 
@@ -9,20 +9,40 @@ from .hash_codec import bits_tensor_to_hash_bytes
 from .scenegraph import SceneGraphMatch, SimpleSceneGraph
 
 
+class ImageHashPipelineOutput(Protocol):
+    """Protocol for the output of ImageHashPipeline.process_batch."""
+
+    hash_bits: Any  # torch.Tensor
+    cropped_images: list[Image.Image]
+
+
+@runtime_checkable
+class ImageHashPipeline(Protocol):
+    """Protocol for an image hash computation pipeline."""
+
+    def process_batch(
+        self,
+        images: list[Image.Image],
+        text_labels: list[str],
+        batch_size: int = 32,
+    ) -> ImageHashPipelineOutput:
+        ...
+
+
 @dataclass(frozen=True)
 class ImageSceneGraphQueryResult:
-    query_crop_index: int
+    query_index: int
     query_hash: bytes
-    query_crop: Image.Image
+    query_crop: Image.Image | None
     matches: list[SceneGraphMatch]
 
 
 def query_image_against_scene_graph(
     image: Image.Image,
-    pipeline: Any,
+    *,
+    pipeline: ImageHashPipeline,
     scene_graph: SimpleSceneGraph,
     text_labels: list[str],
-    *,
     top_k: int = 1,
     batch_size: int = 1,
 ) -> list[ImageSceneGraphQueryResult]:
@@ -31,25 +51,24 @@ def query_image_against_scene_graph(
     cropped_images = list(output.cropped_images)
 
     if hash_bits.numel() == 0:
-        if cropped_images:
-            raise ValueError("hash_bits and cropped_images must align")
         return []
 
     if hash_bits.dim() == 1:
         hash_bits = hash_bits.unsqueeze(0)
 
-    if hash_bits.shape[0] != len(cropped_images):
-        raise ValueError("hash_bits and cropped_images must align")
-
     results: list[ImageSceneGraphQueryResult] = []
-    for crop_index, query_bits in enumerate(hash_bits):
+    for query_index, query_bits in enumerate(hash_bits):
         query_hash = bits_tensor_to_hash_bytes(query_bits)
+        if scene_graph.objects:
             matches = scene_graph.query_by_visual_hash(query_hash, top_k=top_k)
+        else:
+            matches = []
+        crop = cropped_images[query_index] if query_index < len(cropped_images) else None
         results.append(
             ImageSceneGraphQueryResult(
-                query_crop_index=crop_index,
+                query_index=query_index,
                 query_hash=query_hash,
-                query_crop=cropped_images[crop_index],
+                query_crop=crop,
                 matches=matches,
             )
         )

tests/test_query_image_against_scene_graph.py

@@ -0,0 +1,276 @@
+from __future__ import annotations
+
+import sys
+from dataclasses import dataclass
+from pathlib import Path
+
+import numpy as np
+import torch
+from PIL import Image
+
+
+MINI_NAV_DIR = Path(__file__).resolve().parents[1] / "mini-nav"
+sys.path.insert(0, str(MINI_NAV_DIR))
+
+from scenegraph.hash_codec import bits_tensor_to_hash_bytes  # noqa: E402
+from scenegraph.objectnode import ObjectNode  # noqa: E402
+from scenegraph.query import query_image_against_scene_graph  # noqa: E402
+from scenegraph.scenegraph import SimpleSceneGraph  # noqa: E402
+
+
+WIDTH = 512
+
+
+@dataclass(frozen=True)
+class FakePipelineOutput:
+    hash_bits: torch.Tensor
+    cropped_images: list[Image.Image]
+
+
+class FakePipeline:
+    def __init__(self, output: FakePipelineOutput):
+        self.output = output
+        self.calls: list[tuple[list[Image.Image], list[str], int]] = []
+
+    def process_batch(
+        self,
+        images: list[Image.Image],
+        text_labels: list[str],
+        batch_size: int = 32,
+    ) -> FakePipelineOutput:
+        self.calls.append((images, text_labels, batch_size))
+        return self.output
+
+
+def _bits_with_ones(*indices: int) -> torch.Tensor:
+    bits = torch.zeros(WIDTH, dtype=torch.int32)
+    for index in indices:
+        bits[index] = 1
+    return bits
+
+
+def _hash_with_ones(*indices: int) -> bytes:
+    return bits_tensor_to_hash_bytes(_bits_with_ones(*indices))
+
+
+def _image(color: str = "white") -> Image.Image:
+    return Image.new("RGB", (8, 8), color=color)
+
+
+def _node(obj_id: str, hash_bytes: bytes) -> ObjectNode:
+    return ObjectNode(
+        obj_id=obj_id,
+        room_id="room_a",
+        position=np.array([0.0, 0.0, 0.0], dtype=np.float32),
+        visual_hash=hash_bytes,
+        semantic_hash=hash_bytes,
+        hit_count=1,
+        last_seen_frame=0,
+    )
+
+
+def _scene_graph_with_hashes(*items: tuple[str, bytes]) -> SimpleSceneGraph:
+    graph = SimpleSceneGraph()
+    for obj_id, hash_bytes in items:
+        graph.objects[obj_id] = _node(obj_id, hash_bytes)
+    return graph
+
+
+def test_single_query_hash_returns_expected_object_node():
+    query_bits = _bits_with_ones(1, 3)
+    query_hash = bits_tensor_to_hash_bytes(query_bits)
+    other_hash = _hash_with_ones(0)
+    query_crop = _image("blue")
+    pipeline = FakePipeline(
+        FakePipelineOutput(
+            hash_bits=query_bits.unsqueeze(0),
+            cropped_images=[query_crop],
+        )
+    )
+    graph = _scene_graph_with_hashes(("other", other_hash), ("target", query_hash))
+    image = _image("red")
+
+    results = query_image_against_scene_graph(
+        image,
+        pipeline=pipeline,
+        scene_graph=graph,
+        text_labels=["chair", "table"],
+        top_k=1,
+        batch_size=7,
+    )
+
+    assert len(results) == 1
+    assert pipeline.calls == [([image], ["chair", "table"], 7)]
+    assert results[0].query_index == 0
+    assert results[0].query_hash == query_hash
+    assert results[0].query_crop is query_crop
+    assert len(results[0].matches) == 1
+    assert results[0].matches[0].obj_id == "target"
+    assert results[0].matches[0].node is graph.objects["target"]
+
+
+def test_one_image_with_multiple_query_hashes_returns_multiple_result_groups():
+    first_bits = _bits_with_ones(0)
+    second_bits = _bits_with_ones(2, 4)
+    hash_bits = torch.stack([first_bits, second_bits])
+    first_hash = bits_tensor_to_hash_bytes(first_bits)
+    second_hash = bits_tensor_to_hash_bytes(second_bits)
+    first_crop = _image("green")
+    second_crop = _image("yellow")
+    pipeline = FakePipeline(
+        FakePipelineOutput(
+            hash_bits=hash_bits,
+            cropped_images=[first_crop, second_crop],
+        )
+    )
+    graph = _scene_graph_with_hashes(("first", first_hash), ("second", second_hash))
+
+    results = query_image_against_scene_graph(
+        _image("red"),
+        pipeline=pipeline,
+        scene_graph=graph,
+        text_labels=["object"],
+        top_k=1,
+    )
+
+    assert [result.query_index for result in results] == [0, 1]
+    assert [result.query_hash for result in results] == [first_hash, second_hash]
+    assert [result.query_crop for result in results] == [first_crop, second_crop]
+    assert [result.matches[0].obj_id for result in results] == ["first", "second"]
+
+
+def test_top_k_controls_match_count_and_preserves_cam_ordering():
+    query_bits = _bits_with_ones(0, 1, 2)
+    exact_hash = bits_tensor_to_hash_bytes(query_bits)
+    one_bit_off_hash = _hash_with_ones(0, 1)
+    two_bits_off_hash = _hash_with_ones(0)
+    pipeline = FakePipeline(
+        FakePipelineOutput(
+            hash_bits=query_bits.unsqueeze(0),
+            cropped_images=[_image("blue")],
+        )
+    )
+    graph = _scene_graph_with_hashes(
+        ("two_bits_off", two_bits_off_hash),
+        ("exact", exact_hash),
+        ("one_bit_off", one_bit_off_hash),
+    )
+
+    results = query_image_against_scene_graph(
+        _image("red"),
+        pipeline=pipeline,
+        scene_graph=graph,
+        text_labels=["object"],
+        top_k=2,
+    )
+
+    assert [match.obj_id for match in results[0].matches] == ["exact", "one_bit_off"]
+
+
+def test_empty_pipeline_output_returns_empty_list():
+    pipeline = FakePipeline(
+        FakePipelineOutput(
+            hash_bits=torch.empty((0, WIDTH), dtype=torch.int32),
+            cropped_images=[],
+        )
+    )
+    graph = _scene_graph_with_hashes(("obj", _hash_with_ones(0)))
+
+    results = query_image_against_scene_graph(
+        _image("red"),
+        pipeline=pipeline,
+        scene_graph=graph,
+        text_labels=["object"],
+    )
+
+    assert results == []
+
+
+def test_empty_scene_graph_returns_result_group_with_empty_matches():
+    query_bits = _bits_with_ones(0)
+    query_crop = _image("blue")
+    pipeline = FakePipeline(
+        FakePipelineOutput(
+            hash_bits=query_bits.unsqueeze(0),
+            cropped_images=[query_crop],
+        )
+    )
+
+    results = query_image_against_scene_graph(
+        _image("red"),
+        pipeline=pipeline,
+        scene_graph=SimpleSceneGraph(),
+        text_labels=["object"],
+    )
+
+    assert len(results) == 1
+    assert results[0].query_index == 0
+    assert results[0].query_crop is query_crop
+    assert results[0].matches == []
+
+
+def test_missing_crop_becomes_none_and_extra_crop_is_ignored():
+    first_bits = _bits_with_ones(0)
+    second_bits = _bits_with_ones(1)
+    first_hash = bits_tensor_to_hash_bytes(first_bits)
+    second_hash = bits_tensor_to_hash_bytes(second_bits)
+    only_crop = _image("blue")
+    pipeline = FakePipeline(
+        FakePipelineOutput(
+            hash_bits=torch.stack([first_bits, second_bits]),
+            cropped_images=[only_crop],
+        )
+    )
+    graph = _scene_graph_with_hashes(("first", first_hash), ("second", second_hash))
+
+    results = query_image_against_scene_graph(
+        _image("red"),
+        pipeline=pipeline,
+        scene_graph=graph,
+        text_labels=["object"],
+    )
+
+    assert [result.query_crop for result in results] == [only_crop, None]
+
+    extra_crop_pipeline = FakePipeline(
+        FakePipelineOutput(
+            hash_bits=first_bits.unsqueeze(0),
+            cropped_images=[only_crop, _image("yellow")],
+        )
+    )
+
+    extra_crop_results = query_image_against_scene_graph(
+        _image("red"),
+        pipeline=extra_crop_pipeline,
+        scene_graph=graph,
+        text_labels=["object"],
+    )
+
+    assert len(extra_crop_results) == 1
+    assert extra_crop_results[0].query_crop is only_crop
+
+
+def test_scenegraph_package_exports_query_image_api():
+    from scenegraph import (  # noqa: PLC0415
+        ImageHashPipeline,
+        ImageSceneGraphQueryResult,
+        query_image_against_scene_graph as exported_query,
+    )
+    from scenegraph.query import (  # noqa: PLC0415
+        ImageHashPipeline as DirectImageHashPipeline,
+        ImageSceneGraphQueryResult as DirectImageSceneGraphQueryResult,
+        query_image_against_scene_graph as direct_query,
+    )
+
+    assert ImageHashPipeline is DirectImageHashPipeline
+    assert ImageSceneGraphQueryResult is DirectImageSceneGraphQueryResult
+    assert exported_query is direct_query
+
+    import scenegraph  # noqa: PLC0415
+
+    required = {
+        "ImageHashPipeline",
+        "ImageSceneGraphQueryResult",
+        "query_image_against_scene_graph",
+    }
+    assert required <= set(scenegraph.__all__)

tests/test_scenegraph_image_query.py

@@ -5,7 +5,6 @@ from pathlib import Path
 from types import SimpleNamespace
 
 import numpy as np
-import pytest
 import torch
 from PIL import Image
 
@@ -88,11 +87,11 @@ def test_query_image_against_scene_graph_returns_exact_node_match():
     pipeline = FakePipeline(query_bits.unsqueeze(0), [crop])
 
     results = query_image_against_scene_graph(
-        _image(), pipeline, graph, ["a chair"], top_k=1, batch_size=7
+        _image(), pipeline=pipeline, scene_graph=graph, text_labels=["a chair"], top_k=1, batch_size=7
     )
 
     assert len(results) == 1
-    assert results[0].query_crop_index == 0
+    assert results[0].query_index == 0
     assert results[0].query_hash == query_hash
     assert results[0].query_crop is crop
     assert len(results[0].matches) == 1
@@ -114,10 +113,10 @@ def test_query_image_against_scene_graph_returns_one_result_per_query_crop():
     pipeline = FakePipeline(torch.stack([bits_a, bits_b]), [crop_a, crop_b])
 
     results = query_image_against_scene_graph(
-        _image(), pipeline, graph, ["a chair"], top_k=1
+        _image(), pipeline=pipeline, scene_graph=graph, text_labels=["a chair"], top_k=1
     )
 
-    assert [result.query_crop_index for result in results] == [0, 1]
+    assert [result.query_index for result in results] == [0, 1]
     assert [result.query_hash for result in results] == [hash_a, hash_b]
     assert [result.query_crop for result in results] == [crop_a, crop_b]
     assert [result.matches[0].obj_id for result in results] == ["obj_a", "obj_b"]
@@ -133,7 +132,7 @@ def test_query_image_against_scene_graph_preserves_topk_match_order():
     pipeline = FakePipeline(query_bits.unsqueeze(0), [_image("red")])
 
     results = query_image_against_scene_graph(
-        _image(), pipeline, graph, ["object"], top_k=3
+        _image(), pipeline=pipeline, scene_graph=graph, text_labels=["object"], top_k=3
     )
 
     assert [match.obj_id for match in results[0].matches] == [
@@ -148,29 +147,71 @@ def test_query_image_against_scene_graph_returns_empty_list_for_no_hashes():
     pipeline = FakePipeline(torch.empty((0, WIDTH), dtype=torch.int32), [])
 
     results = query_image_against_scene_graph(
-        _image(), pipeline, SimpleSceneGraph(), ["object"]
+        _image(), pipeline=pipeline, scene_graph=SimpleSceneGraph(), text_labels=["object"]
     )
 
     assert results == []
 
 
-def test_query_image_against_scene_graph_rejects_hash_crop_count_mismatch():
-    pipeline = FakePipeline(torch.stack([_bits_with_ones(0), _bits_with_ones(1)]), [_image()])
-
-    with pytest.raises(ValueError, match="hash_bits and cropped_images must align"):
-        query_image_against_scene_graph(
-            _image(), pipeline, SimpleSceneGraph(), ["object"]
+def test_missing_crop_returns_none_and_extra_crop_ignored():
+    """Spec: missing crop index yields None, extra cropped images are ignored."""
+    first_bits = _bits_with_ones(0)
+    second_bits = _bits_with_ones(1)
+    first_hash = bits_tensor_to_hash_bytes(first_bits)
+    second_hash = bits_tensor_to_hash_bytes(second_bits)
+    only_crop = _image("blue")
+    graph = _scene_graph_with_hashes(
+        ("first", first_hash), ("second", second_hash)
     )
 
+    # Fewer cropped_images than hash_bits rows -> missing crop becomes None
+    missing_pipeline = FakePipeline(
+        torch.stack([first_bits, second_bits]), [only_crop]
+    )
+    results = query_image_against_scene_graph(
+        _image("red"),
+        pipeline=missing_pipeline,
+        scene_graph=graph,
+        text_labels=["object"],
+    )
+    assert [result.query_crop for result in results] == [only_crop, None]
+
+    # More cropped_images than hash_bits rows -> extra crop is ignored
+    extra_pipeline = FakePipeline(
+        first_bits.unsqueeze(0),
+        [only_crop, _image("yellow")],
+    )
+    extra_results = query_image_against_scene_graph(
+        _image("red"),
+        pipeline=extra_pipeline,
+        scene_graph=graph,
+        text_labels=["object"],
+    )
+    assert len(extra_results) == 1
+    assert extra_results[0].query_crop is only_crop
+
 
 def test_scenegraph_package_exports_image_query_api():
     from scenegraph import (  # noqa: PLC0415
+        ImageHashPipeline,
         ImageSceneGraphQueryResult,
         query_image_against_scene_graph as exported_query_image_against_scene_graph,
     )
     from scenegraph.query import (  # noqa: PLC0415
+        ImageHashPipeline as DirectImageHashPipeline,
         ImageSceneGraphQueryResult as DirectImageSceneGraphQueryResult,
+        query_image_against_scene_graph as direct_query,
     )
 
+    assert ImageHashPipeline is DirectImageHashPipeline
     assert ImageSceneGraphQueryResult is DirectImageSceneGraphQueryResult
-    assert exported_query_image_against_scene_graph is query_image_against_scene_graph
+    assert exported_query_image_against_scene_graph is direct_query
+
+    import scenegraph  # noqa: PLC0415
+
+    required = {
+        "ImageHashPipeline",
+        "ImageSceneGraphQueryResult",
+        "query_image_against_scene_graph",
+    }
+    assert required <= set(scenegraph.__all__)