docs(v3): reconcile float spec with plan (cast tokens, oracle paths)

Author: tobyhede

docs/plans/2026-06-19-float-encrypted-domain-design.md

@@ -67,8 +67,13 @@ generated by the existing kind-agnostic renderers.
 - **Two widths, one crypto path.** Both encrypt via `Plaintext::Float(Some(x as
   f64))`. `float4` fixtures use only values exactly representable in f32 (e.g.
   `0.5`, `-2.25`, powers of two) so the `real` round-trip is lossless; f32→f64
-  widening is exact and monotonic, so the oracle holds. The bare `float` cast →
-  `float8`.
+  widening is exact and monotonic, so the oracle holds.
+- **Cast tokens — distinct per width** for surface faithfulness even though the
+  ciphertext is identical f64: `float4` → `Cast::REAL` (plaintext column `real`),
+  `float8` → `Cast::DOUBLE` (plaintext column `double precision`). Both resolve to
+  `ColumnType::Float` in `cast_to_column_type`. The bare `float` cast is
+  interchangeable with `double` and routes to `float8`. (Supersedes an earlier
+  note that both would share `Cast::FLOAT`.)
 - **Total order.** `ScalarType` requires `Ord`, which `f32`/`f64` lack. Add thin
   harness newtypes `F4(f32)` / `F8(f64)` implementing `Ord` via `total_cmp` (safe —
   NaN is never stored), `Display`, `Default = 0.0`, and `#[sqlx(transparent)]`
@@ -139,10 +144,11 @@ fixture lists.
   discriminator arm (twin of the `numeric` arm).
 - `tests/sqlx/src/fixtures/scalar_fixture.rs` — a `float` arm (twin of `numeric`:
   `[Hm, Ore]`, pivot-presence asserts).
-- `tests/sqlx/src/fixtures/eql_plaintext.rs` — `PlaintextSqlType` consts
+- `tests/sqlx/src/fixtures/eql_plaintext.rs` — `Cast::REAL` / `Cast::DOUBLE` consts
+  (add if absent; only `Cast::FLOAT` exists today) and `PlaintextSqlType` consts
   (`real` / `double precision`); `cast_for_kind` + `plaintext_sql_type_for_kind`
-  arms for `F32`/`F64` (`Cast::FLOAT` already exists); `Sealed` + `EqlPlaintext`
-  for `F4`/`F8` → `Plaintext::Float(Some(x as f64))`; three mirrored `#[test]`s.
+  arms for `F32`/`F64`; `Sealed` + `EqlPlaintext` for `F4`/`F8` →
+  `Plaintext::Float(Some(x as f64))`; three mirrored `#[test]`s.
 - `tests/sqlx/src/scalar_domains.rs` — `F4`/`F8` newtypes (`Ord` via `total_cmp`,
   `Display`, `Default = 0.0`, `#[sqlx(transparent)]`); `float4_values()` /
   `float8_values()` accessors parsing catalog strings (incl. `"inf"`/`"-inf"`);
@@ -152,8 +158,9 @@ fixture lists.
   lists and the pivot/arbitrary test lists.
 
 ### C. Tests
-- `tests/sqlx/tests/encrypted_domain/{fixture_oracle.rs, e2e_oracle.rs}` — add
-  `float4`/`float8` to both oracle suite lists.
+- `tests/sqlx/tests/encrypted_domain/property/{fixture_oracle.rs, e2e_oracle.rs}` —
+  add `float4`/`float8` to both oracle suite lists. (Oracle suites live under
+  `property/`, not directly under `encrypted_domain/`.)
 - NEW `tests/sqlx/tests/encrypted_domain/float_special.rs` + `#[path]` mod in
   `encrypted_domain.rs` (outside `scalars::`) — the NaN/`±0`/`±Inf` behavioural
   regression suite.