fix: type untyped binds by Ruby class instead of defaulting to INT64

[zhaitz]

Problem

When ActiveRecord hands the adapter a bind that came from a raw SQL placeholder (where("name = ?", "abc") on Rails 8.1, or Arel.sql("name = ?", "abc") on any Rails since 7.1), the value arrives as a bare Ruby object with no attached column type. to_types only knew how to type query attributes, Symbols, and booleans; everything else was declared INT64. A String bind was therefore sent to Spanner labelled as an integer and rejected with Invalid value for bind parameter p1: Expected INT64.

Fix

• New private untyped_bind_type(value) maps a Ruby value's class to an ActiveModel type: String, true/false, Float, BigDecimal, Time/DateTime (via the adapter's own Spanner timestamp type), and Date.
• to_types uses it in its else branch, so the declared Spanner type matches the value.
• to_params uses the same method to pick the serializer, so the encoded value matches the declared type. Previously it always serialised unknown binds through the Integer type.
• Unrecognised values return nil, which preserves the historical behaviour exactly: declared INT64, value sent as-is. (An Integer type instance was deliberately not used as the fallback, since it would silently coerce e.g. Arrays to NULL.)
• Booleans now flow through the shared method via ActiveModel::Type::Boolean; wire result is unchanged.

Tests

• test_untyped_binds_from_arel_sql_are_typed_by_ruby_class sends eight binds through Arel.sql (the seven typed kinds plus an Integer to guard the fallback) and asserts both the type code and encoded value the mock server receives. Passes on ActiveRecord 7.1 and 8.1; fails on both without the fix.
• test_where_with_positional_string_placeholder is the production shape, Singer.where("first_name = ?", "Alice"). Passes on 8.1, skips below 8.1 where Rails still inlines the literal, and fails on 8.1 without the fix.

Full suite has the same result set with and without this change on both versions (the only other failures are pre-existing local json 3.x incompatibilities in the JSON tests).

Net effect

Raw ? placeholders against Spanner work for strings, floats, decimals, timestamps, and dates. The connection.quote and CAST(? AS STRING) workarounds in the api-backend become unnecessary once the fork revision is bumped.

🤖 Generated with Claude Code