topo_sort read graph.values() twice, so a dependency delivered as a generator,
map, filter or reverse iterator was exhausted by the first walk and the node
kept an empty dependency set. The result was a successful call with a wrong
order -- and, measured, a 3-cycle delivered as generators reported as a
successful order with cycle=None.
Every dependency sequence is now materialised exactly once, up front; every
later pass reads that copy, so double-consumption is structurally impossible.
Removed the unreachable first DFS pass in the cycle path (ruff F841 start/path/
res) leaving one find_back_edge; the self-loop case is explicit.
test_toposort.py resolved the module from /root/.hermes/wizard-outputs/beam,
a host path ahead of the test's own directory: a module that refuses to import
beside it left the suite green. It now resolves from Path(__file__).parent and
asserts the imported file's identity. 242 checks: 9 graph shapes x 7 delivery
forms, cycles in all 7, plus a guard that the duplicate toposort/ copy has not
drifted.
Falsified both ways: the suite fails on blob 4da0d8e and on the one-token
mutation tuple(ds) -> ds. CHECK rc 0 (85 unittests OK), verify.py 8/8.
spark
beam