Fix/issue 1 junction surface area

[wiesnerfriedman]

I have read the CLA Document and I hereby sign the CLA.

[cbuahin]

@wiesnerfriedman, any chance we can remove the AMM implementation from this PR so that it dels with the immediate issue referenced?

[Copilot]

Pull request overview

This PR expands dynamic-wave routing configuration/diagnostics and adds a new RDII computation path (AMM), alongside a large set of verification and introspection tests.

Changes:

• Make DW routing respect a configurable MIN_SURFAREA floor in internal units (and adjust node intrinsic surface-area handling for junctions/storage).
• Add an “operator snapshot” API (callback + polling + optional iteration residual history) to expose per-substep DW solver state.
• Introduce an AMM-based RDII option and wire parsing/initialization into the engine; add extensive new unit/integration/concurrency tests and a benchmark.

Reviewed changes

Copilot reviewed 33 out of 35 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
src/engine/hydraulics/Node.cpp/.hpp	Change node intrinsic surface-area rules (junctions now 0; storage returns physical).
src/engine/hydraulics/Routing.cpp	Convert DW options (head_tol, min_surf_area) to internal units at router init.
src/engine/hydraulics/DynamicWave.cpp/.hpp	Add min_surf_area, iteration residual recording, and snapshot population plumbing.
src/engine/core/OperatorSnapshotState.hpp	New per-engine storage for snapshot buffers, callback, polling, iteration history.
include/openswmm/engine/openswmm_operator_snapshot.h	New public C API and snapshot structure definition.
src/engine/core/openswmm_engine_impl.cpp	Add C API entry points for snapshot/callback/polling/iteration history.
src/engine/core/SWMMEngine.cpp/.hpp	Wire snapshot population into routing; add AMM RDII compute path and initialization.
src/engine/hydrology/AMM.cpp/.hpp	New AMM solver implementation + parameter/state definitions.
src/engine/input/handlers/InflowsHandler.cpp/.hpp	Parse [AMM] section and store component definitions + assignments.
src/engine/input/handlers/OptionsHandler.cpp	Parse RDII_METHOD option and store in SimulationOptions.
src/engine/plugins/DefaultInputPlugin.cpp	Register built-in [AMM] section handler.
src/engine/data/InflowData.hpp / src/engine/core/SimulationContext.hpp	Add AMMAssignData to context.
tests/unit/engine/test_routing.cpp	Add regression/unit tests for min surface area behavior and DW node continuity.
tests/unit/engine/test_operator_snapshot.cpp	Add unit tests for snapshot callback + poll behavior.
tests/unit/engine/test_dynamic_preissmann_slot.cpp	Add targeted DPS verification suite.
tests/unit/engine/test_concurrent_engines.cpp	Add concurrency determinism test (two engines in two threads).
tests/benchmarks/bench_operator_snapshot.cpp	Add benchmark for snapshot overhead.
tests/unit/engine/CMakeLists.txt / tests/benchmarks/CMakeLists.txt	Register new unit tests and benchmark targets.
docs/thread_safety_verification.md	Add thread-safety audit report and testing notes.

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[Copilot]

When RDII_METHOD is set to AMM, the engine still unconditionally applies RTK RDII inflows via rdii_.applyRdiiInflows() (and rdii_.computeAll() still runs at the wet-weather step). This will double-count RDII if any [RDII]/[HYDROGRAPHS] data is present. Gate the RTK RDII compute/apply path on rdii_method == RTK (or explicitly document/support running both methods and add a separate option).