NeqSim 3.26.0

Status: prepared release candidate; publication pending. These notes were prepared on 2026-10-20 from master 9d6366f3af86ac79522a533b6c7da3696fc4b310, covering 117 commits after v3.25.0. The version-preparation change does not publish artifacts or create a tag. Open pull requests are outside this snapshot.

Changes included in this snapshot.

Compatibility review before upgrading

JAMA removal and EJML interfaces

PR #4416 removes JAMA from the production and test classpaths. Some former JAMA interfaces now use EJML SimpleMatrix; their old Java method descriptors are not preserved. This candidate therefore includes source, binary, and saved-solver incompatibilities. It must not be described as an entirely backward-compatible minor release. The requested candidate number remains 3.26.0; the release owner must resolve the version and contract classification under repository governance and the API lifecycle policy before publication. An accepted NRC and the required major contract boundary must be recorded for breaking changes; preparing this version does not satisfy or waive those requirements.

Affected integration	Required migration
JamaLinearAlgebra	Use EjmlLinearAlgebra, preferably through the primitive-array LinearAlgebraOperations interface.
ChemicalReactionList.calcReacRates(...)	Adapt to its EJML return value, or prefer the existing array-returning calcReationRates(...).
FluidBoundaryInterface.getMassTransferCoefficientMatrix()	Adapt to SimpleMatrix[], or use getMassTransferCoefficientArray().
Matrix overloads and subclass hooks in StatisticsBaseClass	Rebuild overrides against the EJML signatures; retain dimensions and ownership semantics.
LevenbergMarquardtResult matrix constructor and covariance/correlation accessors	Use EJML arguments or the named fromArrays(...) factory and array accessors.
Serialized SysNewtonRhapsonPhaseEnvelope working state	Recreate UID-1000 solvers from thermodynamic inputs; the current array-based solver uses UID 1001.

Recompile Java integrations and update Python/JVM code that constructs or reads JAMA matrices. Recreate persisted working solvers affected by changed field types; adding the old JAMA JAR does not convert their state. Same-version serialization tests do not establish compatibility with all older saved models. The complete migration guide records the affected interfaces, legacy TP-flash solver boundary, numerical corrections, and tests.

The EJML phase-envelope implementation also rejects volume roots that fail the EOS pressure equation. This corrects false pure-component saturation points rather than restoring the retired numerical backend.

Eclipse E300 critical-volume units

PR #4455 writes VCRIT in m3/kmol and ZCRIT as a dimensionless quantity, and converts critical volumes to NeqSim’s internal cm3/mol on import. Older NeqSim exports could overstate both values by a factor of 1000. Regenerate those files before using them in external reservoir or PVT tools. The reader’s magnitude-based legacy detection does not support mixed-unit blocks or remove the need to verify unusually large critical volumes. See the E300 import and migration guide.

Input validation and changed results

• Unsupported ISO 6976 reference temperatures now fail explicitly instead of silently selecting an unrelated reference condition (#4425).
• Named material, company, vessel-plate, packing, pipe-wall and subsea design lookups reject missing or unsupported data. Check custom databases and explicit overrides before rerunning mechanical designs (#4396, #4397, #4405, #4406, #4407, #4409, #4429).
• Pipeline surface-temperature profiles have explicit unit handling. Review the selected overload and units when migrating older models (#4456).
• The legacy Aspen IP.21/OnlineSignal path is deprecated by #4426, merged after the 3.25.0 tag. Its source annotations name the development revision 3.25.0; 3.26.0 is the first planned published release containing that change. The API remains present. See the historian migration guidance.

Main changes since 3.25.0

Thermodynamics, flashes, and chemistry

• Recover a missing aqueous phase in wet gas-condensate flashes; conserve phase masses and empty-outlet inventories; improve trace-water PS-flash behavior and pure-fluid saturation guards (#4320, #4325, #4428, #4440, #4457).
• Isolate shared mixing-rule and CPA clone state, reset classic HV pair data, and retain wax equilibrium during endpoint cleanup (#4329, #4333, #4363, #4364, #4412, #4415).
• Correct electrolyte derivatives, CO2/KCl response, MEG alias data, DEA identity and chemistry initialization; retain traceable salt-free and full-family Dholabhai hydrate assessments (#4332, #4365, #4367, #4408, #4411, #4441, #4444, #4453, #4466). These assessments retain residuals and limitations; they do not qualify all electrolyte/hydrate mixtures. See CO2/KCl provenance and barite qualification gaps.

Process equipment, networks, and optimization

• Improve compressor speed/efficiency solve reporting, pump-map speed-slice and BEP handling, heater input invalidation, exchanger rating invalidation, and distillation duties calculated from published streams (#4326, #4401, #4410, #4431, #4439, #4445, #4449, #4461).
• Add mapped rotating-equipment power and live injection-route checks; retain failure states and shared-reservoir refinement evidence (#4317, #4322, #4328, #4361, #4371).
• Persist and revalidate field and lifecycle operating-envelope evidence, accepted states, period changes, hard-constraint boundaries, and sampled operating-region transitions (#4312, #4342, #4359, #4370, #4399, #4430, #4447, #4460).
• Add opt-in, experimental non-equilibrium MEG/water film transfer after pigging and conservative signed-face transitions. The film route is isothermal and single-stage Euler with explicit unsupported combinations; do not assume general transient drying qualification (#4282, #4339, #4350, film-transfer guide).
• Add mass-based blending of complete TBP tables and a catalytic-reforming balance, with source-bounded refinery evidence (#4448, #4454, #4465).

Continuous tasks, MCP, and development tools

• Extend living tasks with ensemble calibration, a solve-loop runner, backtesting, drift tuning, persisted handoffs, and living/current-best/final reports. Keep baseline promotion and production use subject to the existing review gates (#4420, #4422, #4468, continuous-task guide).
• Coordinate categorized workflow names, capability-coverage regeneration, retained electrolyte evidence, and numerical validation. Retain the MCP distribution and its own artifact version while updating its NeqSim core dependency to 3.26.0 (#4315, #4374, #4433).

Planned distributions

Distribution	Version or expected asset	Runtime
Core Maven artifact	com.equinor.neqsim:neqsim:3.26.0	Java 17+
Core standalone library	neqsim-3.26.0.jar	Java 17+
Java 8 Maven artifact	com.equinor.neqsim:neqsim:3.26.0-Java8	Java 8+
Java 8 standalone library	neqsim-3.26.0-Java8.jar	Java 8+
MCP runner and checksum	neqsim-mcp-server-3.26.0-runner.jar and .jar.sha256	Java 21+
MCP container	ghcr.io/equinor/neqsim-mcp-server:3.26.0	Container runtime

The MCP module’s own Maven artifact version remains 1.0.0-SNAPSHOT; its revision and neqsim.version resolve to the coordinated core version. The runner’s public filename and container tag use the core release version. The Python package has its own publishing process; changing these POMs does not publish a new Python package.

The wrapper is pinned to Maven 3.9.16, the publishing baseline qualified in 3.25.0 preparation. The Java 8 release profile retains central-publishing 0.11.0 while the standard profile uses 0.12.0. Maven 3.10.0 was reintroduced after 3.25.0, but its known artifact-level metadata issue still affects the retained 0.11.0 profile. Qualify the bundles from both profiles before advancing the wrapper again. Both profiles retain waitUntil=published.

Release completion requirements

1. Complete the compatibility/NRC review above and record the release owner’s version decision. Recheck these notes against the final release commit.
2. Require successful configured CI and security checks on the final candidate, including both supported core configurations, numerical/model specifications, slow-test shards, documentation, formatting, and packaged MCP protocol tests. A skipped numerical job or a same-version serialization test is not evidence of full release compatibility.
3. Build the core Java 17 and Java 8 distributions, sources/Javadoc, and the Java 21 MCP runner; inspect artifact versions, dependencies and checksums. Preserve the Java 8 dependency pins and verify the Java 8 runtime separately.
4. Merge the reviewed version PR. The existing default-branch workflow can create a draft release with built assets; the preparation branch does not authorize publication. Include these migration notes in the release body together with the generated change list.
5. Publish only after the release owner approves. Verify both Maven Central versions reach PUBLISHED, all GitHub assets and the MCP checksum are downloadable, and the MCP container build succeeds. Record the final tag, commit, workflow results and publication time in the release record.

Local and hosted validation evidence belongs in the preparation PR. This document lists candidate changes and required gates; it does not claim those gates have passed or that the planned artifacts already exist.