[CaffeinatedCoder]

Closes #232

Problem

docs/why.md and docs/efcore.md implied the finite-only rule protects every query. It protects every value the application creates, binds and loads. Over a row another tool wrote, a query that runs in the database answers in PostgreSQL's order ([0,NaN) matches Contains(1e308)), and only loading the entity throws (#179, part B).

Change

• docs/efcore.md: a new Keep NaN and infinity out of a float column section. It states the boundary with the issue's three examples and gives one HasCheckConstraint per column kind. The "Only finite values load" bullet links to it. docs/why.md gets the same boundary in "Where is the model stricter than the database?". There are CHANGELOG Docs: lines (root and EF package).
• Measured on PostgreSQL 16.15 and 18.1, and the reason the constraints differ by kind: the bounds check the issue proposes (lower(x) NOT IN ('NaN','Infinity','-Infinity') AND upper(x) …) is complete for a range but not for a multirange. A multirange's lower/upper are its outer bounds, and they are NULL beside an unbounded side, which a CHECK lets pass. So {(,-Infinity],[1,2)}, {(,-Infinity),[1,2)}, {[1,2),[Infinity,)}, {[1,2),(Infinity,)} and {(,0),[1,Infinity),[NaN,)} all pass it. The documented multirange constraint checks the text instead ("Bands"::text !~* '(nan|inf)'; a finite float never prints those letters). The array constraint is NOT ("Weights" && '{NaN,Infinity,-Infinity}').
• Claims E60, E61 and W06, held by the new test.

Tests

• New FloatCheckConstraintTests (integration, PostgreSQL 17 in the suite; the same corpus ran by hand on 16 and 18):
  • Constraints: it reads the three expressions out of the guide's code block, so the SQL a reader pastes is the SQL that runs. It applies them with HasCheckConstraint on float8 and float4 range, multirange and array columns through EnsureCreated. It requires every non-finite literal to fail with 23514 (22 per width, including the five multiranges above) and every finite, unbounded, empty and NULL value to be stored.
  • Boundary: without the constraints, Contains(1e308) over [0,NaN), a range containing a NaN double column, and Count over {1,NaN} answer in PostgreSQL's order, and loading throws ArgumentException.
• Proof: with the issue's bounds check in place of the documented multirange expression, the test fails, because 10 rows are stored (5 multiranges × float8/float4).
• Conventions 395, integration 258.

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