Fix listNeighborhood where filters #1217

src/GraphsDFG/services/graph_ops.jl

@@ -74,18 +74,42 @@ function DFG.listNeighborhood(
         whereSolvable = >=(solvable)
     end
 
-    # find neighbors at distance to add
-    nbhood = Int[]
-
-    for l in variableFactorLabels
-        union!(nbhood, neighborhood(dfg.g, dfg.g.labels[l], distance))
+    # Filter-aware BFS: listNeighbors applies filterDFG! so filtered-out nodes are
+    # never added to the frontier, consistently breaking the traversal chain.
+    # Fast path (no filters): neighborhood() from the graph library is used directly.
+    allvarfacs = if isnothing(whereSolvable) && isnothing(whereTags)
+        nbhood = Int[]
+        for l in variableFactorLabels
+            union!(nbhood, neighborhood(dfg.g, dfg.g.labels[l], distance))
+        end
+        [dfg.g.labels[id] for id in nbhood]
+    else
+        visited = Set{Symbol}(variableFactorLabels)
+        included = copy(variableFactorLabels)
+        frontier = Symbol[]
+        # Seed frontier with starting nodes that pass the filter (they are always
+        # expansion roots regardless, but only passed to listNeighbors if they exist).
+        filterDFG!(included, whereSolvable, l -> getSolvable(dfg, l))
+        filterDFG!(included, whereTags, l -> listTags(dfg, l))
+        append!(frontier, included)
+
+        for _ = 1:distance
+            isempty(frontier) && break
+            next_frontier = Symbol[]
+            for node in frontier
+                for nl in listNeighbors(dfg, node; whereSolvable, whereTags)
+                    if !(nl in visited)
+                        push!(visited, nl)
+                        push!(included, nl)
+                        push!(next_frontier, nl)
+                    end
+                end
+            end
+            frontier = next_frontier
+        end
+        included
     end
 
-    allvarfacs = [dfg.g.labels[id] for id in nbhood]
-
-    filterDFG!(allvarfacs, whereSolvable, l -> getSolvable(dfg, l))
-    filterDFG!(allvarfacs, whereTags, l -> listTags(dfg, l))
-
     variableLabels = intersect(listVariables(dfg), allvarfacs)
     factorLabels = intersect(listFactors(dfg), allvarfacs)
 

src/services/discovery.jl

@@ -118,10 +118,11 @@ end
 """
     $(SIGNATURES)
 Build a list of all unique neighbors inside 'distance'. Neighbors can be filtered by using keyword arguments, eg. [`whereTags`] and [`whereSolvable`].
-Filters are applied to final neighborhood result.
+Filters break the traversal chain: nodes that do not pass the filter are excluded from the result and their neighbors are not explored further.
 
 Notes
 - Returns a tuple `(variableLabels, factorLabels)`, where each element is a `Vector{Symbol}`.
+- The starting `label` itself is subject to filtering.
 
 Related:
 - [`getSubgraph`](@ref)
@@ -134,7 +135,9 @@ function listNeighborhood(dfg::AbstractDFG, label::Symbol, distance::Int; filter
     for dist = 1:distance
         newNeighbors = Set{Symbol}()
         for node in curList
-            neighbors = listNeighbors(dfg, node)
+            # Apply filters during traversal so that filtered-out nodes break the chain:
+            # only neighbors passing the filter are added to the result and frontier.
+            neighbors = listNeighbors(dfg, node; filters...)
             union!(neighborList, neighbors)
             union!(newNeighbors, neighbors)
         end

test/testBlocks.jl

@@ -1541,6 +1541,16 @@ function GettingNeighbors(testDFGAPI; VARTYPE = VariableDFG, FACTYPE = FactorDFG
 
     # Solvable
     #TODO if not a GraphsDFG with and summary or skeleton
+    if VARTYPE == VariableDFG
+        # Chain-breaking: x7x8f1 is solvable=0; x8x9f1 is only reachable through x8 (solvable=0).
+        # With the filter applied during traversal, x8x9f1 must NOT appear in the result.
+        varnh, facnh = listNeighborhood(dfg, [:x7], 4; whereSolvable = >=(1))
+        @test issetequal(varnh, [:x5, :x6, :x7])
+        @test issetequal(facnh, [:x5x6f1, :x6x7f1])
+        @test :x8x9f1 ∉ facnh   # chain-breaking: not reachable through solvable=0 x7x8f1/x8
+        @test :x8 ∉ varnh
+    end
+
     if VARTYPE == VariableDFG
         @test listNeighbors(dfg, :x5; whereSolvable = >=(2)) == Symbol[]
         @test issetequal(listNeighbors(dfg, :x5; whereSolvable = >=(0)), [:x4x5f1, :x5x6f1])