Execution Model

bijux-gnss-nav is computational, but it is not one opaque compute kernel. It executes as a sequence of scientific interpretations.

Normal Flow

1. external product bytes or text enter through a format family
2. typed navigation state is produced for a constellation or reference product
3. correction law interprets observations and product state together
4. one estimator family consumes those inputs and emits a solution, refusal, or evidence record
5. downstream packages decide when and where that scientific result is used

Important Architectural Distinction

The crate may own runtime-neutral helpers such as NavigationEngine and PositionRuntime, but that does not make it the owner of live receiver orchestration. Those types represent navigation behavior, not stage scheduling.

Families With Separate Execution Logic

• product parsing families execute per format family and constellation
• position solvers execute around observation sets and correction chains
• PPP executes as a stateful filter with precise-product policy
• RTK executes through alignment, differencing, ambiguity handling, and baseline-quality evaluation

Why This Matters

Treating all of this as "just nav execution" hides where correctness actually comes from and makes boundary reviews weaker.