Bound indexed retrieval operations

DEVELOPMENT_NOTES.md

@@ -59,9 +59,11 @@ of project size.
 
 The inherited dependency-cycle preparation scanned every edge once for every node. The graph
 validator now constructs dependency adjacency in one edge pass and sorts each adjacency list before
-the existing deterministic depth-first cycle check.
+an iterative deterministic depth-first cycle check. The iterative stack also removes recursion
+depth as a failure mode on large valid graphs. The same edge pass now rejects missing sources as
+well as missing targets.
 
-A 2,000-node regression test counts complete edge-collection iteration passes and caps them at
+A 10,000-node regression test counts complete edge-collection iteration passes and caps them at
 four. The focused correctness and bounded-pass tests pass, and the configured strict source type
 gate is clean.
 
@@ -137,6 +139,21 @@ One audit identified a correctness risk beyond latency: a large mutating MCP ope
 successfully and then be replaced by `result_too_large`. This must be fixed in Milestone 1 so
 exactly-once operations never report a false failure after mutation.
 
+#### Bounded indexed retrieval
+
+Search, metadata filtering, backlinks, dependency traversal, and impact traversal now query one
+extra row beyond the requested bound and report `limit` plus `truncated`. Backlinks, dependency,
+and impact APIs accept the same additive `limit` option through Python, CLI, and MCP surfaces.
+Omitted limits are capped by the project `max_results` policy.
+
+Traversal no longer loads the complete edge table and repeatedly scans it. It performs
+deterministically ordered frontier queries through the existing source primary key or target index.
+Each request also has a deterministic edge-examination budget derived from its result limit. The
+response includes `examined_edges` and `examined_edges_limit` counters so algorithmic work can be
+asserted independently of machine timing. `truncated` is true when either another unique result
+exists or the work budget prevents proving completeness. A focused core, CLI, MCP, Ruff, and
+Pyright gate passes for this work-in-progress slice.
+
 ### Initial design constraints
 
 - Full rebuild remains the recovery and equivalence oracle.

src/docforge/cli.py

@@ -53,6 +53,7 @@ def _parser() -> argparse.ArgumentParser:
             command.add_argument("--relation")
         else:
             command.add_argument("--depth", type=int, default=2)
+        command.add_argument("--limit", type=int)
     context = commands.add_parser("context")
     context.add_argument("profile")
     context.add_argument("--budget", type=int)
@@ -149,11 +150,23 @@ def _run(arguments: argparse.Namespace) -> dict[str, object]:
             limit=arguments.limit,
         )
     if arguments.command == "backlinks":
-        return index.backlinks(arguments.node_id, relation=arguments.relation)
+        return index.backlinks(
+            arguments.node_id,
+            relation=arguments.relation,
+            limit=arguments.limit,
+        )
     if arguments.command == "dependencies":
-        return index.dependencies(arguments.node_id, depth=arguments.depth)
+        return index.dependencies(
+            arguments.node_id,
+            depth=arguments.depth,
+            limit=arguments.limit,
+        )
     if arguments.command == "impact":
-        return index.impact(arguments.node_id, depth=arguments.depth)
+        return index.impact(
+            arguments.node_id,
+            depth=arguments.depth,
+            limit=arguments.limit,
+        )
     if arguments.command == "context":
         return compile_context(index, arguments.profile, arguments.budget)
     if arguments.command == "render":

src/docforge/index.py

@@ -826,14 +826,20 @@ class ProjectIndex:
                 ORDER BY rank, nodes.node_id
                 LIMIT ?
                 """,
-                (expression, bounded),
+                (expression, bounded + 1),
             ).fetchall()
             results: list[dict[str, object]] = []
-            for row in rows:
+            for row in rows[:bounded]:
                 payload = _row_to_node(row).as_dict(include_content=False)
                 payload.update({"rank": row["rank"], "snippet": row["snippet"]})
                 results.append(payload)
-            return snapshot.result(query=query, count=len(results), results=results)
+            return snapshot.result(
+                query=query,
+                count=len(results),
+                limit=bounded,
+                truncated=len(rows) > bounded,
+                results=results,
+            )
 
     def filter_nodes(
         self,
@@ -857,66 +863,146 @@ class ProjectIndex:
         where = f"WHERE {' AND '.join(clauses)}" if clauses else ""
         with self._read_snapshot() as snapshot:
             rows = snapshot.connection.execute(
-                f"SELECT * FROM nodes {where} ORDER BY node_id LIMIT ?", (*values, bounded)
+                f"SELECT * FROM nodes {where} ORDER BY node_id LIMIT ?",
+                (*values, bounded + 1),
             ).fetchall()
-            results = [_row_to_node(row).as_dict(include_content=False) for row in rows]
+            results = [_row_to_node(row).as_dict(include_content=False) for row in rows[:bounded]]
-            return snapshot.result(count=len(results), results=results)
+            return snapshot.result(
+                count=len(results),
+                limit=bounded,
+                truncated=len(rows) > bounded,
+                results=results,
+            )
 
-    def backlinks(self, node_id: str, *, relation: str | None = None) -> dict[str, object]:
+    def backlinks(
-        return self._edges(node_id, incoming=True, relation=relation)
+        self,
+        node_id: str,
+        *,
+        relation: str | None = None,
+        limit: int | None = None,
+    ) -> dict[str, object]:
+        return self._edges(node_id, incoming=True, relation=relation, limit=limit)
 
-    def dependencies(self, node_id: str, *, depth: int = 2) -> dict[str, object]:
+    def dependencies(
-        return self._traverse(node_id, incoming=False, depth=depth, relation="depends_on")
+        self,
+        node_id: str,
+        *,
+        depth: int = 2,
+        limit: int | None = None,
+    ) -> dict[str, object]:
+        return self._traverse(
+            node_id,
+            incoming=False,
+            depth=depth,
+            relation="depends_on",
+            limit=limit,
+        )
 
-    def impact(self, node_id: str, *, depth: int = 2) -> dict[str, object]:
+    def impact(
-        return self._traverse(node_id, incoming=True, depth=depth, relation=None)
+        self,
+        node_id: str,
+        *,
+        depth: int = 2,
+        limit: int | None = None,
+    ) -> dict[str, object]:
+        return self._traverse(
+            node_id,
+            incoming=True,
+            depth=depth,
+            relation=None,
+            limit=limit,
+        )
 
-    def _edges(self, node_id: str, *, incoming: bool, relation: str | None) -> dict[str, object]:
+    def _edges(
+        self,
+        node_id: str,
+        *,
+        incoming: bool,
+        relation: str | None,
+        limit: int | None,
+    ) -> dict[str, object]:
+        bounded = _bounded_limit(
+            limit,
+            self.project.descriptor.limits.max_results,
+            default=self.project.descriptor.limits.max_results,
+        )
         source_column = "target_id" if incoming else "source_id"
         relation_clause = " AND relation = ?" if relation is not None else ""
-        values: tuple[object, ...] = (node_id, relation) if relation is not None else (node_id,)
+        values: tuple[object, ...] = (
+            (node_id, relation, bounded + 1) if relation is not None else (node_id, bounded + 1)
+        )
         with self._read_snapshot() as snapshot:
             self._require_node(snapshot.connection, node_id)
             rows = snapshot.connection.execute(
                 f"SELECT source_id, relation, target_id FROM edges "
                 f"WHERE {source_column} = ?{relation_clause} "
-                "ORDER BY source_id, relation, target_id",
+                "ORDER BY source_id, relation, target_id LIMIT ?",
                 values,
             ).fetchall()
-            return snapshot.result(edges=[Edge(*row).as_dict() for row in rows])
+            truncated = len(rows) > bounded
+            edges = [Edge(*row).as_dict() for row in rows[:bounded]]
+            return snapshot.result(
+                count=len(edges),
+                limit=bounded,
+                truncated=truncated,
+                edges=edges,
+            )
 
     def _traverse(
-        self, node_id: str, *, incoming: bool, depth: int, relation: str | None
+        self,
+        node_id: str,
+        *,
+        incoming: bool,
+        depth: int,
+        relation: str | None,
+        limit: int | None,
     ) -> dict[str, object]:
         maximum = self.project.descriptor.limits.max_traversal_depth
         if type(depth) is not int or depth < 0 or depth > maximum:
             raise DocForgeError("invalid_depth", "Traversal depth is outside the configured limit")
+        bounded = _bounded_limit(
+            limit,
+            self.project.descriptor.limits.max_results,
+            default=self.project.descriptor.limits.max_results,
+        )
+        examined_limit = (bounded + 1) ** 2
+        source_column = "target_id" if incoming else "source_id"
+        relation_clause = " AND relation = ?" if relation is not None else ""
         with self._read_snapshot() as snapshot:
             self._require_node(snapshot.connection, node_id)
-            edges = tuple(
-                Edge(*row)
-                for row in snapshot.connection.execute(
-                    "SELECT source_id, relation, target_id FROM edges "
-                    "ORDER BY source_id, relation, target_id"
-                )
-            )
             queue: deque[tuple[str, int, tuple[str, ...]]] = deque([(node_id, 0, (node_id,))])
             seen = {node_id}
             results: list[dict[str, object]] = []
-            while queue:
+            truncated = False
+            examined_edges = 0
+            while queue and len(results) <= bounded and examined_edges < examined_limit:
                 current, current_depth, path = queue.popleft()
                 if current_depth >= depth:
                     continue
-                candidates = [
+                remaining = examined_limit - examined_edges
-                    edge
+                values: tuple[object, ...] = (
-                    for edge in edges
+                    (current, relation, remaining + 1)
-                    if (relation is None or edge.relation == relation)
+                    if relation is not None
-                    and ((edge.target_id if incoming else edge.source_id) == current)
+                    else (current, remaining + 1)
-                ]
+                )
-                for edge in candidates:
+                candidates = snapshot.connection.execute(
+                    "SELECT source_id, relation, target_id FROM edges "
+                    f"WHERE {source_column} = ?{relation_clause} "
+                    "ORDER BY source_id, relation, target_id LIMIT ?",
+                    values,
+                ).fetchall()
+                if len(candidates) > remaining:
+                    truncated = True
+                    candidates = candidates[:remaining]
+                examined_edges += len(candidates)
+                for row in candidates:
+                    edge = Edge(*row)
                     target = edge.source_id if incoming else edge.target_id
                     if target in seen:
                         continue
+                    if len(results) >= bounded:
+                        truncated = True
+                        break
                     seen.add(target)
                     target_path = (*path, target)
                     results.append(
@@ -928,10 +1014,16 @@ class ProjectIndex:
                         }
                     )
                     queue.append((target, current_depth + 1, target_path))
+            if queue and examined_edges >= examined_limit:
+                truncated = True
             return snapshot.result(
                 root=node_id,
                 depth=depth,
                 count=len(results),
+                limit=bounded,
+                truncated=truncated,
+                examined_edges=examined_edges,
+                examined_edges_limit=examined_limit,
                 results=results,
             )
 

src/docforge/mcp_server.py

@@ -577,22 +577,36 @@ def _create_bound_server(service: DocForgeService, *, read_only: bool) -> FastMC
         )
 
     @server.tool(name="docforge_backlinks")
-    def backlinks(node_id: str, relation: str | None = None) -> dict[str, Any]:
+    def backlinks(
+        node_id: str,
+        relation: str | None = None,
+        limit: int | None = None,
+    ) -> dict[str, Any]:
         """Return bounded incoming relationships for one exact stable node."""
 
-        return service.invoke(lambda: service.index.backlinks(node_id, relation=relation))
+        return service.invoke(
+            lambda: service.index.backlinks(node_id, relation=relation, limit=limit)
+        )
 
     @server.tool(name="docforge_dependencies")
-    def dependencies(node_id: str, depth: int = 2) -> dict[str, Any]:
+    def dependencies(
+        node_id: str,
+        depth: int = 2,
+        limit: int | None = None,
+    ) -> dict[str, Any]:
         """Traverse declared depends_on relationships within the configured depth limit."""
 
-        return service.invoke(lambda: service.index.dependencies(node_id, depth=depth))
+        return service.invoke(lambda: service.index.dependencies(node_id, depth=depth, limit=limit))
 
     @server.tool(name="docforge_impact")
-    def impact(node_id: str, depth: int = 2) -> dict[str, Any]:
+    def impact(
+        node_id: str,
+        depth: int = 2,
+        limit: int | None = None,
+    ) -> dict[str, Any]:
         """Traverse bounded incoming relationships and report exact paths."""
 
-        return service.invoke(lambda: service.index.impact(node_id, depth=depth))
+        return service.invoke(lambda: service.index.impact(node_id, depth=depth, limit=limit))
 
     @server.tool(name="docforge_get_context")
     def get_context(profile: str, budget: int | None = None) -> dict[str, Any]:

tests/test_core.py

@@ -333,6 +333,9 @@ class DocForgeCoreTests(unittest.TestCase):
             self.assertEqual(
                 ["proof.validation"], [item["node_id"] for item in filtered["results"]]
             )
+            limited_filter = index.filter_nodes(limit=1)
+            self.assertEqual(1, limited_filter["count"])
+            self.assertTrue(limited_filter["truncated"])
             dependencies = index.dependencies("guide.workflow", depth=2)
             self.assertEqual(
                 ["guide.foundation"], [item["node_id"] for item in dependencies["results"]]
@@ -346,6 +349,23 @@ class DocForgeCoreTests(unittest.TestCase):
                 ["guide.workflow", "proof.validation"],
                 [item["node_id"] for item in impact["results"]],
             )
+            limited = index.impact("guide.foundation", depth=2, limit=1)
+            self.assertEqual(["guide.workflow"], [item["node_id"] for item in limited["results"]])
+            self.assertEqual(1, limited["limit"])
+            self.assertTrue(limited["truncated"])
+            self.assertLessEqual(
+                limited["examined_edges"],
+                limited["examined_edges_limit"],
+            )
+
+            complete_limit = index.dependencies("guide.workflow", depth=2, limit=1)
+            self.assertEqual(1, complete_limit["count"])
+            self.assertFalse(complete_limit["truncated"])
+
+            limited_backlinks = index.backlinks("guide.workflow", limit=1)
+            self.assertEqual(1, limited_backlinks["count"])
+            self.assertEqual(1, limited_backlinks["limit"])
+            self.assertFalse(limited_backlinks["truncated"])
 
     def test_query_rechecks_source_identity_before_returning(self) -> None:
         with tempfile.TemporaryDirectory() as directory:

tests/test_mcp_server.py

@@ -131,9 +131,15 @@ class DocForgeMcpTests(unittest.IsolatedAsyncioTestCase):
                 ("docforge_get_logic", {"owner_node_id": "guide.workflow"}),
                 ("docforge_search", {"query": "canonical nodes", "limit": 5}),
                 ("docforge_filter_nodes", {"family": "proof", "tag": "validation"}),
-                ("docforge_backlinks", {"node_id": "guide.workflow"}),
+                ("docforge_backlinks", {"node_id": "guide.workflow", "limit": 5}),
-                ("docforge_dependencies", {"node_id": "guide.workflow", "depth": 2}),
+                (
-                ("docforge_impact", {"node_id": "guide.foundation", "depth": 2}),
+                    "docforge_dependencies",
+                    {"node_id": "guide.workflow", "depth": 2, "limit": 5},
+                ),
+                (
+                    "docforge_impact",
+                    {"node_id": "guide.foundation", "depth": 2, "limit": 5},
+                ),
                 ("docforge_get_context", {"profile": "active", "budget": 180}),
                 ("docforge_validate_project", {}),
                 ("docforge_render_status", {}),