SysMD (tukcps/SysMD 4.3.0): currency bug + toolchain build gap; patches on our fork, not yet sent upstream #92

Record of what the SysMD evaluation found and where the patches live. Context: the kr0ki/SysMD overlap review and PromptExecution/ufo-types#31 / #89.

Fork

https://github.com/PromptExecution/SysMD (fork of tukcps/SysMD, base development at v4.3.0)

The bug (reproduced, not assumed)

Before the fix, via a characterization test on 4.3.0:

100 USD + 100 EUR          -> 199.99999999999997  unit [EUR]   (no error)
100 USD .valueIn("EUR")    -> 100                              (no rate)
1 GBP   .valueIn("USD")    -> 1.0
Quantity(100, "USD").unit  -> "EUR"

There is no fixed exchange rate, so the solver can satisfy constraints that mix currencies.

Verification

• Baseline on an unmodified checkout (with the toolchain patch only): 1,722 tests, 0 failures, 103 skipped.
• With the currency fix: 1,727 tests, 0 failures. The pre-existing currency() and usdGbpCurrencies() tests still pass.
• Both patches apply cleanly with git am onto upstream development.
• Side effect to mention upstream: running the suite modifies the tracked fixture src/test/resources/saveAndLoadProjectData/project/.project.json.

Upstream status: NOT sent

CONTRIBUTING.md says the main project is the CPS chair's GitLab and contributions are made by emailing a diff to the maintainers; the address in the file is truncated (cgrimm|herzog@). Public commit metadata shows cgrimm@rptu.de and herzogm@rptu.de; unconfirmed. The GitHub repo appears to be a mirror (it has an open roadmap issue, tukcps/SysMD#2).

• Confirm recipient, then email the two patches (format-patch files can be regenerated from the fork branches) or open a GitHub issue/PR on the mirror if the maintainers prefer it
• Note upstream that the currency semantics (explicit FX vs. distinct units) is theirs to decide; our patch is the conservative option (distinct units, no implicit conversion)

Related, not part of the patches

• Concepts we transferred (as data, no code) into ufo-types: interval quantities with explicit currency, range verdicts, hasA/isA edits. Views are unsupported in SysMD, so project views come from the SysML v2 standard library.
• SysMD sidecar for numeric/unit constraint solving is designed but not built: headless (bootRun --args=headless, port 8081), contract POST /projects -> POST /session -> PUT /session/model (CodeRequest, runlevel SOLVED) -> GET /session/variables.