Structured Decomposition
Structured decomposition is an engineering agent pattern where a long-horizon generation problem is split into a pipeline of narrow agents connected by typed intermediate representations, with a deterministic checkpoint at every handoff. No single model owns the workflow end-to-end; each agent produces a bounded, validatable artifact.
The strongest current evidence comes from the University of Miami / HBC Engineering structural analysis paper (arXiv 2606.06525): a multi-agent pipeline converts structured natural-language briefs of irregular 3D frames into executable SAP2000 models at 90% mean accuracy (response agreement within 1% of reference models), while direct single-model generation with GPT-5.4 and Gemini-3.1 Pro scores 0% under the same test.
Why decomposition is the mechanism, not a preference
Complete engineering scripts are a long-horizon generation problem: small errors accumulate across thousands of lines that must preserve spatial meaning, shared topology, and software-specific syntax. The ablation results show each architectural element carries the load:
| Ablation | Effect |
|---|---|
| Remove floor decomposition (intermediate representation) | Accuracy drops to 20–50% |
| Merge node/girder/slab agents into one | Accuracy drops to 50–70% |
| Merge translation and compilation stages | Accuracy drops to 0% |
The decisive design choice is not the number of agents. It is the presence of explicit intermediate representations and deterministic acceptance criteria at each boundary.
The pattern, generalized
- Intent capture — extract requirements into a typed contract (geometry, materials, boundary conditions, loads, scope)
- Domain representation — convert the hard reasoning problem into a stable intermediate form the agent can reliably manipulate (here: a matrix-of-stories → per-floor occupancy maps)
- Narrow generation agents — parallelizable agents with single responsibilities (nodes, girders, slabs, columns)
- Deterministic checkpoints — reject duplicate nodes, undefined endpoints, invalid corners, disconnected geometry before downstream processing
- Staged translation and assembly — produce executable software commands in steps, never in one pass
- Engineer release authority — generated models remain draft artifacts until a licensed engineer verifies them
A secondary platform insight: the pipeline assigns different models by task capability (a larger model for spatial reasoning, a lighter model for code translation), keeping cost near $0.19 and runtime near 175 seconds per case.
Relationship to FEA-in-the-loop
FEAInTheLoop and structured decomposition are complementary halves of the same governance architecture:
- Structured decomposition validates during generation — checkpoints block invalid intermediate artifacts before they propagate
- FEA-in-the-loop validates after generation — simulation produces typed failure evidence that drives repair
Both reject the same failure mode: asking one general-purpose model to own an entire engineering workflow and trusting plausible-looking output. The structural analysis paper’s 0% direct-generation baselines independently corroborate the FEA paper’s finding that first-shot generation is not enough for industrial use.
Boundary
The 90% benchmark covers ten author-designed orthogonal frame cases with standardized loads and materials. Not yet demonstrated: nonorthogonal or curved geometry, dynamic/seismic/wind response, shear walls and bracing, requirement diversity, regulatory compliance, or model certification. Data and code are available only on request, limiting reproducibility. Keep licensed engineer sign-off mandatory; pilot in shadow mode against trusted reference models.
Related
- FEAInTheLoop — the complementary post-generation validation-and-repair loop
- BoundedAgent — structured decomposition is bounding applied inside the generation pipeline
- EnterpriseAgentGovernance — checkpoint records, artifact versions, and approval form the audit trail governance requires
- ManufacturingAndPhysicalAI — broader engineering agent adoption context