Found while validating python-sdk's new flows_to/slice verbs (python-sdk#270, PR python-sdk#297) end-to-end against 1.1.0. Audit corpus: the python-sdk cldk/ package at -a 4 — 758 callables, 29,562 ddg edges, 5,031 spanned body vertices.

1. The interprocedural port layer is an island

Observed ddg edge patterns across the entire corpus (src-class → dst-class):

Port wiring: 2,673 formal_in ports — 0 with outgoing ddg; 2,431 formal_out ports — 0 with incoming ddg. Meanwhile the app level emits 1,961 param_in + 1,788 param_out edges and per-call summary edges between those same ports.

So the SDG is two disconnected graphs: a statement-level ddg, and a port lattice (actual_in → formal_in, formal_out → actual_out, actual_in → actual_out) nothing flows into or out of. Consequences for any consumer:

• flows_to(def_stmt, callee_formal) can never find a path — an end-to-end "this value reaches that parameter" witness is inexpressible; only port-to-port segments work.
• Return-value flow (x = f(y) → uses of x) dies at actual_out.
• Inside the callee, parameter flow is carried by @entry → stmt var edges, duplicating what formal_in → stmt should carry — so entering via param_in dead-ends at formal_in.

Missing edge classes (the fix checklist):

• def stmt → actual_in:k (argument binding at the call site)
• actual_out → use stmt (return-value binding)
• formal_in:k → first-use stmts (or re-root the parameter's entry edges at the port)
• return stmt → formal_out

Note: codeanalyzer-typescript already emits stmt → formal_out under the same schema (verified on its L4 sample), so the vocabulary supports this today — no schema change needed, emission only.

2. Every call vertex is off the CFG spine

1,781 of 5,031 spanned body vertices are touched by zero cfg edges — and all 1,781 are kind: call. A slice(edges=("cfg",)) or any cfg-reachability walk never visits a call site. If calls are intended as dataflow satellites of their statement, that design deserves a schema note; otherwise they should sit on the spine (stmt → call → next or a stmt —contains→ call link).

Minimal repro: any 2-function project at -a 4 (the python-sdk tests/resources/cpg/py-a4.json "pyfix" sample exhibits every one of these). Related: #112 (persist max_level in the Neo4j emit).