## Diamond Recursion Scan — Deeper Scan Notes

**Scan date:** 2026-03-29
**Pattern:** Recursive cycle/dependency check without visited set (CWE-407 diamond recursion, O(2^D))

### Summary

**nx-0001 (existing)** covers `recursive_simple_cycles` B defaultdict(list) O(N²).
**nx-0002 (existing)** covers `all_node_cuts` seen-list O(K²).

### Additional functions checked — CLEAN

- `dag.py descendants/ancestors`: uses `bfs_edges` which employs a visited set internally — CLEAN.
- `dag.py has_cycle`: uses `topological_generations` which is iterative with a visited set — CLEAN.
- `algorithms/chains.py chain_decomposition`: uses explicit `visited = set()` — CLEAN.
- All other DAG algorithms in `networkx/algorithms/dag.py` use proper visited sets.

### Verdict: No additional diamond recursion defects found beyond nx-0001 and nx-0002
