feat: direction-aware reranker text in GraphRAG hop-and-filter (#1016)

The reranker document text now reflects the traversal direction,
showing only the new information relative to the frontier entity:
- From S (subject is frontier): text = "{predicate} {object}"
- From O (object is frontier): text = "{subject} {predicate}"
- From P (predicate is frontier): text = "{subject} {object}"

This eliminates duplicate reranker texts when traversing inward
from shared object nodes (e.g. 18 CPUs all producing identical
"hasSubcategory Processors" text when the subject was dropped).

execute_batch_triple_queries now returns (triple, direction)
tuples so hop_and_filter can select the appropriate text format.

Updates tech spec to document the direction-aware approach.
Adds unit tests for direction tracking and reranker text
construction.

docs/tech-specs/graph-rag-semantic-filter.md

@@ -224,12 +224,27 @@ The current embedding pre-filter represents each edge as
 - **Drop commas.**  Commas add tokenisation noise without semantic
   value.
 
-- **Drop the subject.**  The subject identifies which entity the
-  edge belongs to, but it does not contribute to whether the
-  edge's content is relevant to the query.  The predicate and
-  object carry the semantic meaning — what relationship exists
-  and what it connects to.  Representing edges as `"{p} {o}"`
-  produces cleaner cross-encoder matches.
+- **Direction-aware text.**  The reranker text should highlight
+  the *new* information relative to the traversal direction.
+  The frontier entity is already known context — repeating it
+  adds noise and, when traversing from an object node, causes
+  many edges to produce identical reranker text (e.g. 18
+  products sharing the same `hasSubcategory Processors` triple
+  all collapse to the same string when the subject is dropped).
+
+  The text is constructed based on which position the frontier
+  entity occupied in the triple:
+
+  - **From subject** (s=entity): `"{predicate} {object}"` —
+    the subject is known, predicate and object are new.
+  - **From object** (o=entity): `"{subject} {predicate}"` —
+    the object is known, subject and predicate are new.
+  - **From predicate** (p=entity): `"{subject} {object}"` —
+    the predicate is known, subject and object are new.
+
+  This eliminates the duplicate-text problem that arises when
+  traversing inward from a shared object node, and gives the
+  cross-encoder a more informative signal at every hop.
 
 #### Remove the embedding pre-filter (step 3)
 
@@ -389,7 +404,10 @@ no LLM call.  These fields are dropped from the Focus entity.
 
    a. Retrieve all edges one hop from the current frontier nodes.
 
-   b. Represent each edge as `"{predicate} {object}"`.
+   b. Represent each edge using direction-aware text: from a
+      subject node use `"{predicate} {object}"`, from an object
+      node use `"{subject} {predicate}"`, from a predicate node
+      use `"{subject} {object}"`.
 
    c. Score edges against the extracted concepts using the
       cross-encoder service.

tests/unit/test_concurrency/test_graph_rag_concurrency.py

@@ -129,6 +129,9 @@ class TestBatchTripleQueries:
 
         # 3 queries, alternating results
         assert len(result) == 3
+        # Each result is a (triple, direction) tuple
+        for triple, direction in result:
+            assert direction in (Query.FROM_S, Query.FROM_P, Query.FROM_O)
 
     @pytest.mark.asyncio
     async def test_exception_in_one_query_does_not_block_others(self):
@@ -153,6 +156,8 @@ class TestBatchTripleQueries:
 
         # 3 queries: 2 succeed, 1 fails → 2 triples
         assert len(result) == 2
+        for triple, direction in result:
+            assert direction in (Query.FROM_S, Query.FROM_P, Query.FROM_O)
 
     @pytest.mark.asyncio
     async def test_none_results_filtered(self):
@@ -176,6 +181,8 @@ class TestBatchTripleQueries:
 
         # 3 queries: 1 returns None, 2 return triples
         assert len(result) == 2
+        for triple, direction in result:
+            assert direction in (Query.FROM_S, Query.FROM_P, Query.FROM_O)
 
     @pytest.mark.asyncio
     async def test_empty_entities_no_queries(self):
@@ -220,6 +227,80 @@ class TestBatchTripleQueries:
         assert calls[2].kwargs["p"] is None
         assert calls[2].kwargs["o"] == "ent-1"
 
+    @pytest.mark.asyncio
+    async def test_directions_assigned_correctly(self):
+        """Each query position should produce the correct direction tag."""
+        triple = _make_triple("s", "p", "o")
+
+        call_count = 0
+
+        async def one_triple_each(**kwargs):
+            nonlocal call_count
+            call_count += 1
+            return [triple]
+
+        client = AsyncMock()
+        client.query_stream = one_triple_each
+        query = _make_query(triples_client=client)
+
+        result = await query.execute_batch_triple_queries(
+            ["e1"], limit_per_entity=10
+        )
+
+        assert len(result) == 3
+        # Order matches query order: s-position, p-position, o-position
+        assert result[0][1] == Query.FROM_S
+        assert result[1][1] == Query.FROM_P
+        assert result[2][1] == Query.FROM_O
+
+    @pytest.mark.asyncio
+    async def test_directions_correct_for_multiple_entities(self):
+        """Direction tags cycle correctly across multiple entities."""
+        triple = _make_triple("s", "p", "o")
+        client = AsyncMock()
+        client.query_stream = AsyncMock(return_value=[triple])
+        query = _make_query(triples_client=client)
+
+        result = await query.execute_batch_triple_queries(
+            ["e1", "e2"], limit_per_entity=10
+        )
+
+        assert len(result) == 6
+        expected_directions = [
+            Query.FROM_S, Query.FROM_P, Query.FROM_O,
+            Query.FROM_S, Query.FROM_P, Query.FROM_O,
+        ]
+        for (_, direction), expected in zip(result, expected_directions):
+            assert direction == expected
+
+    @pytest.mark.asyncio
+    async def test_direction_preserved_with_multiple_triples(self):
+        """All triples from one query share the same direction."""
+        t1 = _make_triple("a", "p1", "b")
+        t2 = _make_triple("a", "p2", "c")
+
+        call_count = 0
+
+        async def multi_results(**kwargs):
+            nonlocal call_count
+            call_count += 1
+            if call_count == 1:
+                return [t1, t2]
+            return []
+
+        client = AsyncMock()
+        client.query_stream = multi_results
+        query = _make_query(triples_client=client)
+
+        result = await query.execute_batch_triple_queries(
+            ["e1"], limit_per_entity=10
+        )
+
+        # First query (FROM_S) returns 2 triples, both should be FROM_S
+        assert len(result) == 2
+        assert result[0] == (t1, Query.FROM_S)
+        assert result[1] == (t2, Query.FROM_S)
+
 
 class TestLRUCacheWithTTL:
 

tests/unit/test_retrieval/test_graph_rag_direction_aware_text.py

@@ -0,0 +1,353 @@
+"""
+Tests for direction-aware reranker text in GraphRAG hop-and-filter.
+
+The reranker document text varies by traversal direction:
+- From S (subject is the frontier entity): text = "{p} {o}"
+- From O (object is the frontier entity): text = "{s} {p}"
+- From P (predicate is the frontier entity): text = "{s} {o}"
+"""
+
+import pytest
+from unittest.mock import MagicMock, AsyncMock
+
+from trustgraph.retrieval.graph_rag.graph_rag import Query, LRUCacheWithTTL
+from trustgraph.schema import Term, IRI, LITERAL
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+def _make_rag(reranker_results=None):
+    """Create a mock GraphRag with all clients stubbed."""
+    rag = MagicMock()
+    rag.label_cache = LRUCacheWithTTL()
+    rag.triples_client = AsyncMock()
+    rag.reranker_client = AsyncMock()
+
+    # Label lookups return empty (fall back to URI)
+    rag.triples_client.query.return_value = []
+
+    if reranker_results is not None:
+        rag.reranker_client.rerank.return_value = reranker_results
+    else:
+        rag.reranker_client.rerank.return_value = []
+
+    return rag
+
+
+def _make_query(rag, max_path_length=1, edge_limit=25):
+    return Query(
+        rag=rag,
+        collection="test",
+        verbose=False,
+        entity_limit=50,
+        triple_limit=30,
+        max_subgraph_size=1000,
+        max_path_length=max_path_length,
+        edge_limit=edge_limit,
+    )
+
+
+def _make_schema_triple(s, p, o):
+    """Create a mock triple matching the schema interface."""
+    t = MagicMock()
+    t.s = s
+    t.p = p
+    t.o = o
+    return t
+
+
+def _reranker_result(document_id, query_id="0", score=0.9):
+    r = MagicMock()
+    r.document_id = str(document_id)
+    r.query_id = str(query_id)
+    r.score = score
+    return r
+
+
+# ---------------------------------------------------------------------------
+# Tests: execute_batch_triple_queries direction tracking
+# ---------------------------------------------------------------------------
+
+class TestDirectionTracking:
+
+    @pytest.mark.asyncio
+    async def test_from_s_direction(self):
+        """Triples from s=entity queries are tagged FROM_S."""
+        triple = _make_schema_triple("ent1", "pred", "obj")
+        rag = _make_rag()
+
+        async def query_stream(s=None, p=None, o=None, **kwargs):
+            if s is not None:
+                return [triple]
+            return []
+
+        rag.triples_client.query_stream.side_effect = query_stream
+        q = _make_query(rag)
+
+        result = await q.execute_batch_triple_queries(["ent1"], 10)
+
+        from_s = [(t, d) for t, d in result if d == Query.FROM_S]
+        assert len(from_s) == 1
+        assert from_s[0][0] is triple
+
+    @pytest.mark.asyncio
+    async def test_from_o_direction(self):
+        """Triples from o=entity queries are tagged FROM_O."""
+        triple = _make_schema_triple("subj", "pred", "ent1")
+        rag = _make_rag()
+
+        async def query_stream(s=None, p=None, o=None, **kwargs):
+            if o is not None:
+                return [triple]
+            return []
+
+        rag.triples_client.query_stream.side_effect = query_stream
+        q = _make_query(rag)
+
+        result = await q.execute_batch_triple_queries(["ent1"], 10)
+
+        from_o = [(t, d) for t, d in result if d == Query.FROM_O]
+        assert len(from_o) == 1
+        assert from_o[0][0] is triple
+
+    @pytest.mark.asyncio
+    async def test_from_p_direction(self):
+        """Triples from p=entity queries are tagged FROM_P."""
+        triple = _make_schema_triple("subj", "ent1", "obj")
+        rag = _make_rag()
+
+        async def query_stream(s=None, p=None, o=None, **kwargs):
+            if p is not None:
+                return [triple]
+            return []
+
+        rag.triples_client.query_stream.side_effect = query_stream
+        q = _make_query(rag)
+
+        result = await q.execute_batch_triple_queries(["ent1"], 10)
+
+        from_p = [(t, d) for t, d in result if d == Query.FROM_P]
+        assert len(from_p) == 1
+        assert from_p[0][0] is triple
+
+
+# ---------------------------------------------------------------------------
+# Tests: hop_and_filter reranker document text
+# ---------------------------------------------------------------------------
+
+class TestDirectionAwareRerankerText:
+
+    @pytest.mark.asyncio
+    async def test_from_s_uses_predicate_object(self):
+        """From-S traversal: reranker text should be '{p} {o}'."""
+        triple = _make_schema_triple(
+            "http://ex/entity-A",
+            "http://ex/likes",
+            "http://ex/entity-B",
+        )
+        reranker_result = _reranker_result(0)
+        rag = _make_rag(reranker_results=[reranker_result])
+
+        async def query_stream(s=None, p=None, o=None, **kwargs):
+            if s is not None:
+                return [triple]
+            return []
+
+        rag.triples_client.query_stream.side_effect = query_stream
+
+        q = _make_query(rag, max_path_length=1, edge_limit=10)
+
+        await q.hop_and_filter(
+            seed_entities=["http://ex/entity-A"],
+            concepts=["likes"],
+        )
+
+        call_args = rag.reranker_client.rerank.call_args
+        documents = call_args.kwargs["documents"]
+        # Text should be "{p} {o}" — the URIs since no labels found
+        assert len(documents) == 1
+        assert documents[0]["text"] == "http://ex/likes http://ex/entity-B"
+
+    @pytest.mark.asyncio
+    async def test_from_o_uses_subject_predicate(self):
+        """From-O traversal: reranker text should be '{s} {p}'."""
+        triple = _make_schema_triple(
+            "http://ex/entity-A",
+            "http://ex/likes",
+            "http://ex/entity-B",
+        )
+        reranker_result = _reranker_result(0)
+        rag = _make_rag(reranker_results=[reranker_result])
+
+        async def query_stream(s=None, p=None, o=None, **kwargs):
+            if o is not None:
+                return [triple]
+            return []
+
+        rag.triples_client.query_stream.side_effect = query_stream
+
+        q = _make_query(rag, max_path_length=1, edge_limit=10)
+
+        await q.hop_and_filter(
+            seed_entities=["http://ex/entity-B"],
+            concepts=["likes"],
+        )
+
+        call_args = rag.reranker_client.rerank.call_args
+        documents = call_args.kwargs["documents"]
+        assert len(documents) == 1
+        assert documents[0]["text"] == "http://ex/entity-A http://ex/likes"
+
+    @pytest.mark.asyncio
+    async def test_from_p_uses_subject_object(self):
+        """From-P traversal: reranker text should be '{s} {o}'."""
+        triple = _make_schema_triple(
+            "http://ex/entity-A",
+            "http://ex/likes",
+            "http://ex/entity-B",
+        )
+        reranker_result = _reranker_result(0)
+        rag = _make_rag(reranker_results=[reranker_result])
+
+        async def query_stream(s=None, p=None, o=None, **kwargs):
+            if p is not None:
+                return [triple]
+            return []
+
+        rag.triples_client.query_stream.side_effect = query_stream
+
+        q = _make_query(rag, max_path_length=1, edge_limit=10)
+
+        await q.hop_and_filter(
+            seed_entities=["http://ex/likes"],
+            concepts=["entity"],
+        )
+
+        call_args = rag.reranker_client.rerank.call_args
+        documents = call_args.kwargs["documents"]
+        assert len(documents) == 1
+        assert documents[0]["text"] == "http://ex/entity-A http://ex/entity-B"
+
+    @pytest.mark.asyncio
+    async def test_mixed_directions_produce_different_text(self):
+        """Edges from different directions use different text formats."""
+        triple_from_s = _make_schema_triple(
+            "http://ex/seed", "http://ex/rel", "http://ex/target",
+        )
+        triple_from_o = _make_schema_triple(
+            "http://ex/other", "http://ex/ref", "http://ex/seed",
+        )
+
+        rag = _make_rag(reranker_results=[
+            _reranker_result(0), _reranker_result(1),
+        ])
+
+        async def query_stream(s=None, p=None, o=None, **kwargs):
+            if s == "http://ex/seed":
+                return [triple_from_s]
+            if o == "http://ex/seed":
+                return [triple_from_o]
+            return []
+
+        rag.triples_client.query_stream.side_effect = query_stream
+
+        q = _make_query(rag, max_path_length=1, edge_limit=10)
+
+        await q.hop_and_filter(
+            seed_entities=["http://ex/seed"],
+            concepts=["test"],
+        )
+
+        call_args = rag.reranker_client.rerank.call_args
+        documents = call_args.kwargs["documents"]
+        texts = {d["text"] for d in documents}
+
+        # From S: "{p} {o}" = "http://ex/rel http://ex/target"
+        assert "http://ex/rel http://ex/target" in texts
+        # From O: "{s} {p}" = "http://ex/other http://ex/ref"
+        assert "http://ex/other http://ex/ref" in texts
+
+    @pytest.mark.asyncio
+    async def test_labels_applied_to_direction_text(self):
+        """Labels should be resolved and used in the direction-aware text."""
+        triple = _make_schema_triple(
+            "http://ex/entity-A",
+            "http://ex/likes",
+            "http://ex/entity-B",
+        )
+        reranker_result = _reranker_result(0)
+        rag = _make_rag(reranker_results=[reranker_result])
+
+        LABEL = "http://www.w3.org/2000/01/rdf-schema#label"
+
+        async def query_stream(s=None, p=None, o=None, **kwargs):
+            if s is not None and p is None:
+                return [triple]
+            return []
+
+        async def label_query(s=None, p=None, o=None, limit=1, **kwargs):
+            if p == LABEL:
+                labels = {
+                    "http://ex/entity-A": "Alice",
+                    "http://ex/likes": "likes",
+                    "http://ex/entity-B": "Bob",
+                }
+                if s in labels:
+                    return [MagicMock(o=labels[s])]
+            return []
+
+        rag.triples_client.query_stream.side_effect = query_stream
+        rag.triples_client.query.side_effect = label_query
+
+        q = _make_query(rag, max_path_length=1, edge_limit=10)
+
+        await q.hop_and_filter(
+            seed_entities=["http://ex/entity-A"],
+            concepts=["friendship"],
+        )
+
+        call_args = rag.reranker_client.rerank.call_args
+        documents = call_args.kwargs["documents"]
+        assert len(documents) == 1
+        # From S with labels: "{p_label} {o_label}"
+        assert documents[0]["text"] == "likes Bob"
+
+    @pytest.mark.asyncio
+    async def test_no_duplicate_text_from_shared_object(self):
+        """Multiple edges sharing an object should produce distinct texts."""
+        triple_a = _make_schema_triple(
+            "http://ex/cpu-A", "http://ex/hasCategory", "http://ex/Processors",
+        )
+        triple_b = _make_schema_triple(
+            "http://ex/cpu-B", "http://ex/hasCategory", "http://ex/Processors",
+        )
+
+        rag = _make_rag(reranker_results=[
+            _reranker_result(0), _reranker_result(1),
+        ])
+
+        async def query_stream(s=None, p=None, o=None, **kwargs):
+            if o == "http://ex/Processors":
+                return [triple_a, triple_b]
+            return []
+
+        rag.triples_client.query_stream.side_effect = query_stream
+
+        q = _make_query(rag, max_path_length=1, edge_limit=10)
+
+        await q.hop_and_filter(
+            seed_entities=["http://ex/Processors"],
+            concepts=["CPUs"],
+        )
+
+        call_args = rag.reranker_client.rerank.call_args
+        documents = call_args.kwargs["documents"]
+        texts = [d["text"] for d in documents]
+
+        assert len(texts) == 2
+        # From O: "{s} {p}" — subjects differ, so texts differ
+        assert texts[0] != texts[1]
+        assert "http://ex/cpu-A" in texts[0]
+        assert "http://ex/cpu-B" in texts[1]

trustgraph-flow/trustgraph/retrieval/graph_rag/graph_rag.py

@@ -241,38 +241,56 @@ class Query:
         self.rag.label_cache.put(cache_key, label)
         return label
 
+    FROM_S = "from_s"
+    FROM_P = "from_p"
+    FROM_O = "from_o"
+
     async def execute_batch_triple_queries(self, entities, limit_per_entity):
-        """Execute triple queries for multiple entities concurrently."""
+        """Execute triple queries for multiple entities concurrently.
+
+        Returns a list of (triple, direction) tuples where direction
+        indicates which position the frontier entity occupied.
+        """
         tasks = []
+        directions = []
 
         for entity in entities:
-            tasks.extend([
+            tasks.append(
                 self.rag.triples_client.query_stream(
                     s=entity, p=None, o=None,
                     limit=limit_per_entity,
                     collection=self.collection,
                     batch_size=20, g="",
                 ),
+            )
+            directions.append(self.FROM_S)
+
+            tasks.append(
                 self.rag.triples_client.query_stream(
                     s=None, p=entity, o=None,
                     limit=limit_per_entity,
                     collection=self.collection,
                     batch_size=20, g="",
                 ),
+            )
+            directions.append(self.FROM_P)
+
+            tasks.append(
                 self.rag.triples_client.query_stream(
                     s=None, p=None, o=entity,
                     limit=limit_per_entity,
                     collection=self.collection,
                     batch_size=20, g="",
-                )
-            ])
+                ),
+            )
+            directions.append(self.FROM_O)
 
         results = await asyncio.gather(*tasks, return_exceptions=True)
 
         all_triples = []
-        for result in results:
+        for direction, result in zip(directions, results):
             if not isinstance(result, Exception) and result is not None:
-                all_triples.extend(result)
+                all_triples.extend((triple, direction) for triple in result)
 
         return all_triples
 
@@ -325,7 +343,8 @@ class Query:
             # Deduplicate and filter already-seen edges
             hop_triples = []
             hop_term_map = {}
-            for triple in triples:
+            hop_directions = {}
+            for triple, direction in triples:
                 triple_tuple = (str(triple.s), str(triple.p), str(triple.o))
                 if triple_tuple[1] == LABEL:
                     continue
@@ -336,6 +355,7 @@ class Query:
                 hop_term_map[triple_tuple] = (
                     to_term(triple.s), to_term(triple.p), to_term(triple.o),
                 )
+                hop_directions[triple_tuple] = direction
 
             if not hop_triples:
                 visited_entities.update(frontier)
@@ -361,7 +381,10 @@ class Query:
                 else:
                     label_map[entity] = entity
 
-            # Build labeled edges and documents for cross-encoder
+            # Build labeled edges and documents for cross-encoder.
+            # The reranker text highlights the NEW information relative
+            # to the traversal direction: arriving from S means p,o are
+            # new; from O means s,p are new; from P means s,o are new.
             labeled_hop = []
             for s, p, o in hop_triples:
                 ls = label_map.get(s, s)
@@ -369,10 +392,18 @@ class Query:
                 lo = label_map.get(o, o)
                 labeled_hop.append((ls, lp, lo))
 
-            documents = [
-                {"id": str(i), "text": f"{lp} {lo}"}
-                for i, (ls, lp, lo) in enumerate(labeled_hop)
-            ]
+            documents = []
+            for i, (triple_tuple, (ls, lp, lo)) in enumerate(
+                zip(hop_triples, labeled_hop)
+            ):
+                direction = hop_directions[triple_tuple]
+                if direction == self.FROM_S:
+                    text = f"{lp} {lo}"
+                elif direction == self.FROM_O:
+                    text = f"{ls} {lp}"
+                else:
+                    text = f"{ls} {lo}"
+                documents.append({"id": str(i), "text": text})
 
             queries = [
                 {"id": str(i), "text": c}