[CaffeinatedCoder]

Closes #187

Stacked on #188 (feat/value-object-arithmetic); the translation (#190) stacks on this one.

Problem

EF translates an operator node as the database's arithmetic over the columns and never calls the operator's method. A hand-written operator therefore ran as the database's arithmetic, not as written. With a + that rounds to cents, measured on SQLite (EF Core 10.0.12) with the refusal taken out, over 1.005 and 0.001:

• Price + Tax > 1.006 became ef_compare(ef_add("l"."Price", "l"."Tax"), @limit) > 0 and kept no row, where memory keeps the one.
• Select(l => l.Price + l.Tax) read 1.006, where memory reads 1.01.

Decision 122 keeps such an operator as a seam, so the build can't stop it. The query has to.

Change

• TranslatedAsWrappedArithmeticAttribute is new, [EditorBrowsable(Never)], in CodoMetis.TypeKit.CompilerServices. ValueObjectArithmeticAspect puts it on every operator it generates, via CodeAnnotations.TranslatedAsWrappedArithmetic.
• ValueObjectArithmetic (EF) holds an IQueryExpressionInterceptor, and a finalizing convention for query filters, named or not.
  • They reject any arithmetic, bitwise or shift operator a value object declares without the mark, naming the value object and .Value.
  • A filter fails when the model is built. An operator over the context's own values runs in memory and stays allowed.
  • Conversion operators are left to EF.
• DatabaseReads moves out of HandWrittenOrdering and is now shared with the new convention.
• Docs:
  • EF README, Queries: "Your own operator can't run in the database".
  • docs/value-objects.md, the EF bullet.
  • Generators README, "Write your own members".
  • The changelog, under Fixed.
• Records: decision 123 (refines 122); notes in design/ef-core.md, aspects.md and packages.md.
• Oracles: 6 claims (C28-ef-own-operator-*, C28-generated-operators-marked, E18-own-operator-*).

Tests

• HandWrittenArithmeticTests covers the input class, every operator a value object can declare:
  • +, * without an interface, unary -, |, ~ and a validated value object's +;
  • in a filter, a projection, a checked context and OrderBy, over an optional operand and over a navigation;
  • in query filters, named or not.
  • What stays allowed: the generated - beside a hand-written +, arithmetic on .Value, and an operator over captured values, in a query and in a filter.
• ArithmeticTests.A_generated_operator_is_marked_…: every generated ProbeMoney operator carries the mark, and no hand-written one does.
• Each guard proven by reverting it:
  • Refusal taken out: 13 tests fail (the measurement above).
  • Mark not generated: every generated operator is rejected, 95 query tests fail. Loud, not silent.
  • Filter convention unregistered: 2 tests fail.
  • Filters no longer skipping what runs in memory: the captured-values test fails.
• Full suite: 30,981 passed, 924 skipped (as before), with SQL Server on Azure SQL Edge.

Weaving review

1. Reach. The mark is added where the operator is introduced, and the test reads it on every generated operator. Without it the result is loud (everything rejected), not silent.
2. Discovery. By the attribute on the operator's MethodInfo and GeneratedValueObjectAttribute, never by name.
3. EF. Queries via QueryCompilationStarting, filters at model finalizing, navigations included. Decision 57's ordering refusal is untouched.
4. Packaging. The base package gains one attribute and stays Metalama-free. No reflection beyond GetCustomAttribute, and the package still builds IsAotCompatible.

Review fix (41f0155)

An outside review found that && and || bypassed the refusal: over a value object with operator true and false they are AndAlso and OrElse nodes whose method is its & or |, and Switch && Switch returned true where the operators answer false. Both are refused now. HandWrittenArithmeticTests gains them in a projection and a filter, and || in a query filter; reverting the two entries fails all five. A condition over operator true compiles to a call of op_True, which EF runs in memory as written; that stays allowed and is tested. EF suite 20,165 passed, 915 skipped, on SQLite, PostgreSQL and Azure SQL Edge.

🤖 Generated with Claude Code