paper §7.2: heterogeneous cross-model topology result (per-role model)

Adds the Phase C result: five backends (Claude/Kimi/GLM/Gemini/Groq) as
interchangeable role-agents, per-node model selection via node.attrs["agent"],
and a 3-config drafter->refiner sweep judged for quality. Heterogeneous
GLM->Gemini won over the all-Claude baseline — an existence proof of
"which model wins which role in which topology." Notes quota-bounded sweep
scope as future work.

Co-Authored-By: Claude Opus 4.8 <[email protected]>

papers/dynamic-agentic-topologies.md

@@ -172,6 +172,40 @@ on whether the user optimizes for quality (debate) or value (pipeline) — a cho
 the platform surfaces rather than hard‑codes. The §5 safety result is unchanged
 across all three: authority is topology‑invariant.
 
+### 7.2 Heterogeneous cross‑model topologies (per‑role model selection)
+
+Because a node binds to an agent only at run time, the *model* behind each role is
+itself a free variable — orthogonal to topology and to the §5 safety surface. The
+platform exposes five subscription/API backends as interchangeable role‑agents on a
+single runtime — **Claude** (Sonnet‑4.6), **Kimi** (K2‑coding), **GLM** (4.7/5.2,
+Zhipu), **Gemini** (2.5‑flash), and **Groq** (Llama‑3.3‑70b) — each driven by alias
+over the runtime gateway. A topology can therefore assign a *different vendor's
+model to each role*; assignment is declared per node in the graph
+(`node.attrs["agent"]`), so one run request specifies a full heterogeneous cast
+with no server reconfiguration.
+
+We ran a fixed 2‑stage pipeline (drafter → refiner) on *"Draft, then refine, a
+one‑sentence mission statement for a nonprofit teaching coding to refugees"* under
+three model assignments, scored by an independent Claude judge for clarity, impact,
+and concision:
+
+| Assignment (drafter → refiner) | Judge rank |
+|--------------------------------|:----------:|
+| GLM‑4.7 → Gemini‑2.5‑flash (heterogeneous) | **1st** |
+| Claude → Claude (homogeneous) | 2nd |
+| Kimi → Claude (heterogeneous) | 3rd |
+
+The heterogeneous **GLM→Gemini** cast won — the GLM draft plus Gemini's terse
+refinement produced the most concise, on‑brief statement, beating the homogeneous
+all‑Claude baseline. This is an existence proof of the platform's distinctive
+question — *which model wins which role in which topology* — and confirms model
+choice is a per‑role lever the platform can sweep without touching topology or
+safety. (Costs are billed to each vendor's subscription, not per‑token; the run
+journal records per‑step tokens where the backend surfaces them — Claude/GLM/Gemini
+do, the Kimi CLI's stream path does not.) A larger model×role×topology sweep is
+future work (§8), bounded by the subscription plans' 5‑hour/weekly quotas and
+concurrency caps, which favor sequential pipelines over wide swarm/mesh fan‑out.
+
 ## 8. Limitations and future work
 
 - Results are offline; the production path (real models + tool‑using turns with