Fix recursion data types

src/util/references.util.ts

@@ -229,6 +229,50 @@ const decodeParameterName = (name: string): { nodeFunctionId: string; paramIndex
   return { nodeFunctionId, paramIndexFromName };
 };
 
+/**
+ * Maximum property depth for reference path extraction through recursive data
+ * types. Only applies to types that participate in a reference cycle: the
+ * visited set keeps each individual branch finite, but a cluster of mutually
+ * recursive types still allows combinatorially many simple paths, so those are
+ * additionally depth-capped. Non-recursive nesting is traversed exhaustively.
+ */
+const MAX_REFERENCE_DEPTH = 7;
+
+/**
+ * Determines whether an object type participates in a reference cycle, i.e. can
+ * reach itself again through its (non-nullable) property types. Results are
+ * memoized in the given cache since the same named types repeat throughout a
+ * traversal. The DFS itself is guarded by its own seen set, so it terminates on
+ * cycles that do not lead back to the start type.
+ */
+const isRecursiveType = (
+  type: ts.Type,
+  checker: ts.TypeChecker,
+  cache: Map<ts.Type, boolean>
+): boolean => {
+  const cached = cache.get(type);
+  if (cached !== undefined) return cached;
+
+  const seen = new Set<ts.Type>();
+  const reachesStart = (current: ts.Type): boolean => {
+    if (seen.has(current) || !isRealObjectType(current)) return false;
+    seen.add(current);
+
+    for (const property of current.getProperties()) {
+      if (!property.valueDeclaration) continue;
+      const propType = checker.getNonNullableType(
+        checker.getTypeOfSymbolAtLocation(property, property.valueDeclaration)
+      );
+      if (propType === type || reachesStart(propType)) return true;
+    }
+    return false;
+  };
+
+  const result = reachesStart(type);
+  cache.set(type, result);
+  return result;
+};
+
 /**
  * Recursively extracts object properties from a type that match an expected type.
  *
@@ -243,6 +287,8 @@ const decodeParameterName = (name: string): { nodeFunctionId: string; paramIndex
  * @param checker - TypeScript TypeChecker for type comparison operations
  * @param expectedType - The target type to match when extracting properties
  * @param currentPath - The current property path being built during recursion (default: empty array)
+ * @param visited - Object types already on the current traversal branch, used to break cycles in recursive data types
+ * @param recursionCache - Memoization cache for isRecursiveType, shared across the whole traversal
  * @returns An array of objects containing the property path and the type at that path
  *
  * @example
@@ -253,7 +299,9 @@ const extractObjectProperties = (
   type: ts.Type,
   checker: ts.TypeChecker,
   expectedType: ts.Type,
-  currentPath: ReferencePath[] = []
+  currentPath: ReferencePath[] = [],
+  visited: Set<ts.Type> = new Set(),
+  recursionCache: Map<ts.Type, boolean> = new Map()
 ): Array<{ path: ReferencePath[]; type: ts.Type }> => {
   const results: Array<{ path: ReferencePath[]; type: ts.Type }> = [];
 
@@ -274,17 +322,30 @@ const extractObjectProperties = (
   // Recursively traverse into object properties. Traversal also runs on the
   // non-nullable type: a nullable object in the chain (e.g. `{bla?: TEXT} | null`)
   // is a union whose getProperties() is empty, which would cut off all nested paths.
-  if (isRealObjectType(nonNullableType)) {
+  // Recursive data types (e.g. Order.delivery.order) are cut off via the visited
+  // set — the checker caches type identities, so a cycle revisits the same ts.Type
+  // object. The set only tracks the current branch (backtracked below) so the same
+  // type may still appear on sibling paths. The depth cap only applies to types
+  // that are part of a reference cycle (checked last, it's the expensive test);
+  // purely nested non-recursive objects are traversed to arbitrary depth.
+  if (
+    isRealObjectType(nonNullableType) &&
+    !visited.has(nonNullableType) &&
+    (currentPath.length < MAX_REFERENCE_DEPTH ||
+      !isRecursiveType(nonNullableType, checker, recursionCache))
+  ) {
     const properties = nonNullableType.getProperties();
     if (properties && properties.length > 0) {
+      visited.add(nonNullableType);
       properties.forEach((property) => {
         const propType = checker.getTypeOfSymbolAtLocation(property, property.valueDeclaration!);
         const propName = property.getName();
         const newPath = [...currentPath, { path: propName }];
 
         // Recurse into nested properties
-        results.push(...extractObjectProperties(propType, checker, expectedType, newPath));
+        results.push(...extractObjectProperties(propType, checker, expectedType, newPath, visited, recursionCache));
       });
+      visited.delete(nonNullableType);
     }
   }
 

test/schema/schema.test.ts

@@ -899,4 +899,155 @@ describe("Schema", () => {
         ).toBe(true);
     });
 
+    it('offers all paths of a deeply nested non-recursive object as ReferenceValue suggestions', () => {
+        // Node 1: custom::test::deeply_nested(): a 10-level nested object ending in TEXT.
+        // Node 2: std::text::split(value: TEXT, delimiter: TEXT): LIST<TEXT>
+        //
+        // Reference path extraction caps traversal depth only for recursive data
+        // types. A deeply nested but acyclic object must be traversed exhaustively,
+        // so even the leaf 10 levels down is offered as a suggestion.
+        const DEEPLY_NESTED_FN: FunctionDefinition = {
+            id: "gid://sagittarius/FunctionDefinition/9004",
+            identifier: "custom::test::deeply_nested",
+            signature: "(): { l1: { l2: { l3: { l4: { l5: { l6: { l7: { l8: { l9: { l10: TEXT } } } } } } } } } }",
+        };
+
+        const flow: Flow = {
+            id: "gid://sagittarius/Flow/1",
+            startingNodeId: "gid://sagittarius/NodeFunction/1",
+            signature: "(): void",
+            nodes: {
+                nodes: [
+                    {
+                        id: "gid://sagittarius/NodeFunction/1",
+                        functionDefinition: {identifier: "custom::test::deeply_nested"},
+                        nextNodeId: "gid://sagittarius/NodeFunction/2",
+                        parameters: {
+                            nodes: [],
+                        },
+                    },
+                    {
+                        id: "gid://sagittarius/NodeFunction/2",
+                        functionDefinition: {identifier: "std::text::split"},
+                        parameters: {
+                            nodes: [
+                                {value: null},
+                                {value: {__typename: "LiteralValue", value: ","}},
+                            ],
+                        },
+                    },
+                ],
+            },
+        };
+
+        const [valueSchema] = getSignatureSchema(
+            flow,
+            DATA_TYPES,
+            [...FUNCTION_SIGNATURES, DEEPLY_NESTED_FN],
+            "gid://sagittarius/NodeFunction/2",
+        );
+
+        // value: TEXT → free-form text input.
+        expect(valueSchema.schema.input).toBe("text");
+
+        const paths = ((valueSchema.schema.suggestions ?? []) as any[])
+            .filter(
+                (s) =>
+                    s.__typename === "ReferenceValue" &&
+                    s.nodeFunctionId === "gid://sagittarius/NodeFunction/1",
+            )
+            .map((s) => (s.referencePath ?? []).map((p: any) => p.path).join("."));
+
+        expect(paths).toContain("l1.l2.l3.l4.l5.l6.l7.l8.l9.l10");
+    });
+
+    it('cuts cycles and depth-caps traversal of recursive data types', () => {
+        // Two families of recursive data types, both returned by node 1:
+        //
+        // 1. A mutually recursive pair (RECURSIVE_ORDER ↔ RECURSIVE_CUSTOMER), the
+        //    same shape external actions ship for entity graphs (e.g. Shopware's
+        //    order → delivery → order). A branch must stop as soon as a type
+        //    already on it reappears, instead of overflowing the stack.
+        //
+        // 2. A cycle of 8 distinct types (CHAIN_1 → … → CHAIN_8 → CHAIN_1). The
+        //    per-branch cycle cut alone would allow simple paths through all 8
+        //    types, so recursive types are additionally depth-capped at 7 levels.
+        const RECURSIVE_DATA_TYPES = [
+            {identifier: "RECURSIVE_ORDER", genericKeys: [], type: "{ id: TEXT; customer?: RECURSIVE_CUSTOMER | null }"},
+            {identifier: "RECURSIVE_CUSTOMER", genericKeys: [], type: "{ name: TEXT; lastOrder?: RECURSIVE_ORDER | null }"},
+            {identifier: "CHAIN_1", genericKeys: [], type: "{ value: TEXT; next?: CHAIN_2 | null }"},
+            {identifier: "CHAIN_2", genericKeys: [], type: "{ value: TEXT; next?: CHAIN_3 | null }"},
+            {identifier: "CHAIN_3", genericKeys: [], type: "{ value: TEXT; next?: CHAIN_4 | null }"},
+            {identifier: "CHAIN_4", genericKeys: [], type: "{ value: TEXT; next?: CHAIN_5 | null }"},
+            {identifier: "CHAIN_5", genericKeys: [], type: "{ value: TEXT; next?: CHAIN_6 | null }"},
+            {identifier: "CHAIN_6", genericKeys: [], type: "{ value: TEXT; next?: CHAIN_7 | null }"},
+            {identifier: "CHAIN_7", genericKeys: [], type: "{ value: TEXT; next?: CHAIN_8 | null }"},
+            {identifier: "CHAIN_8", genericKeys: [], type: "{ value: TEXT; next?: CHAIN_1 | null }"},
+        ];
+
+        const RECURSIVE_FN: FunctionDefinition = {
+            id: "gid://sagittarius/FunctionDefinition/9005",
+            identifier: "custom::test::recursive",
+            signature: "(): { pair: RECURSIVE_ORDER; chain: CHAIN_1 }",
+        };
+
+        const flow: Flow = {
+            id: "gid://sagittarius/Flow/1",
+            startingNodeId: "gid://sagittarius/NodeFunction/1",
+            signature: "(): void",
+            nodes: {
+                nodes: [
+                    {
+                        id: "gid://sagittarius/NodeFunction/1",
+                        functionDefinition: {identifier: "custom::test::recursive"},
+                        nextNodeId: "gid://sagittarius/NodeFunction/2",
+                        parameters: {
+                            nodes: [],
+                        },
+                    },
+                    {
+                        id: "gid://sagittarius/NodeFunction/2",
+                        functionDefinition: {identifier: "std::text::split"},
+                        parameters: {
+                            nodes: [
+                                {value: null},
+                                {value: {__typename: "LiteralValue", value: ","}},
+                            ],
+                        },
+                    },
+                ],
+            },
+        };
+
+        const [valueSchema] = getSignatureSchema(
+            flow,
+            [...DATA_TYPES, ...RECURSIVE_DATA_TYPES],
+            [...FUNCTION_SIGNATURES, RECURSIVE_FN],
+            "gid://sagittarius/NodeFunction/2",
+        );
+
+        // value: TEXT → free-form text input.
+        expect(valueSchema.schema.input).toBe("text");
+
+        const paths = ((valueSchema.schema.suggestions ?? []) as any[])
+            .filter(
+                (s) =>
+                    s.__typename === "ReferenceValue" &&
+                    s.nodeFunctionId === "gid://sagittarius/NodeFunction/1",
+            )
+            .map((s) => (s.referencePath ?? []).map((p: any) => p.path).join("."));
+
+        // Properties inside the cycle are still reachable …
+        expect(paths).toContain("pair.id");
+        expect(paths).toContain("pair.customer.name");
+        // … but the branch stops where RECURSIVE_ORDER would reappear on it.
+        expect(paths).not.toContain("pair.customer.lastOrder.id");
+
+        // The chain is walked through distinct types up to the depth cap of 7
+        // (chain + 5×next + value) …
+        expect(paths).toContain("chain.next.next.next.next.next.value");
+        // … and no further, even though the next type would still be new to the branch.
+        expect(paths).not.toContain("chain.next.next.next.next.next.next.value");
+    });
+
 })