Continuous integration

CI tests a small, explicit environment matrix instead of an accidental Cartesian product. The public package bounds in trading_engine.opam define supported dependencies. The repository lock defines the reproducible development baseline.

Cell	Operating system	OCaml	Dependencies	Gate	Status
check	Ubuntu latest	5.5.0	Exact lock	Full make check	Required
lowest-ubuntu	Ubuntu latest	5.5.0	Oldest solver-valid versions inside declared bounds	Full dependency-band check	Required
highest-ubuntu	Ubuntu latest	5.5.0	Newest solver-valid versions inside declared bounds	Full dependency-band check	Required
highest-macos	macOS 15	5.5.0	Newest solver-valid versions inside declared bounds	Build and exact journal comparison	Informational

The lower and upper cells resolve against the current opam repository. They deliberately test the range declared by the package rather than pretending to be reproducible locks. A failure in either required Ubuntu cell means the declared support bounds or the implementation must change. The macOS cell is an early portability signal while Ubuntu remains the supported build platform.

Every runtime cell replays the frozen v3 demo, v5 demo, and v5 risk-limited fill scenarios under TZ=UTC and the C locale. It compares the resulting journal files byte for byte with their canonical fixtures. Standard output and standard error are captured separately because human diagnostics may contain platform-specific paths or process details and are not part of the journal contract. The full test suite additionally validates and replays the current v16 batch, stream, journal, and strategy-v12 fixtures, including quote/trade causality and the reconciled first valuation.

Coverage runs once in the exact locked Ubuntu environment. The required Persistra job also runs once against its full pinned commit; it is not repeated across dependency or operating-system cells. The manually dispatched Persistra moving-head job remains informational.

Feature-branch pushes do not start CI; the pull-request event owns that validation and avoids a duplicate check set. Pull requests cancel superseded commits. Push validation runs only on develop and tags, where it is never cancelled, so durable integration evidence is not discarded. The concurrency key combines the source repository and source branch without colliding with a fork or another branch.