The netstandard2.0 layout guard called decimal.GetBits(decimal), which
allocates a four-element array on first use. That contradicted the
unqualified no-allocation criterion, and the warmed-up allocation test
could not have caught it: warm-up triggers type initialization before
measurement starts.

Seed the probe from decimal(int, int, int, bool, byte) instead. The
constructor defines the logical representation just as GetBits does, so
the check is no weaker, and it touches nothing on the heap.

Also isolate the guard in a decimal-specific helper so a layout failure
cannot disable integer, date, TimeSpan, and Guid formatting, and store
its outcome rather than throwing from the initializer, so callers see
PlatformNotSupportedException instead of TypeInitializationException
wrapping it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AZTXiVaNguCvmjrTjwWLfQ

None of these change the design; they stop the plan from asserting more
than is true.

- The read-path rationale claimed every text-accepting TryGetXxx
  reformats to validate. Nine do; TryGetDecimal, TryGetChar, and
  TryGetUri accept text without reformatting.
- "The remaining canonical encodings are ASCII" excluded nothing, but
  Char is included in that set and may be non-ASCII. Scope it to the
  non-text encodings and name the exception.
- bytesWritten is not guaranteed to equal charsWritten for the
  text-bearing kinds, rather than never equal to it: ASCII String, Char,
  and Uri values still have equal counts, so the assertion has to be
  conditioned on content.
- The one-implementation criterion read as banning the decimal
  extraction and transcoding shims the plan itself specifies. Require one
  canonical renderer, and confine target-specific code to those two
  shims, neither of which decides the output text.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AZTXiVaNguCvmjrTjwWLfQ

Tighten the allocation-free canonical formatting plan from 248 to 191
lines. All 17 acceptance criteria and every normative instruction are
preserved; the reduction is redundant prose, upstream line counts, and a
Scope section whose content already appeared elsewhere.

Restore five justifications that the condensation had removed:

- the derivations of MaximumDayNumber and MaximumTimeOfDayTicks, which
  netstandard2.0 cannot check against a BCL type
- why the encodings must be adapted rather than rederived: the TryGetXxx
  validators pin them, so a wrong rule breaks data already on the wire
- the evidence that the decimal layout assumption is real, namely that
  GetBits documents the logical representation and upstream DecCalc
  carries an explicit BIGENDIAN layout
- Numbers/ as the established provenance pattern to follow
- the rule behind the serializer adoption bullets: the writer transcodes
  UTF-16 itself and receives UTF-8 only for ASCII kinds

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AZTXiVaNguCvmjrTjwWLfQ

Add shared UTF-16 and UTF-8 canonical formatters for primitive metadata values, and route validation and JSON serialization through allocation-free span paths. Cover the new contracts with cross-asset tests, allocation assertions, benchmarks, provenance, and plan-deviation documentation.

Unify floating-point formatting under the partial CanonicalTextFormatter and expose the low-level CanonicalCodeUnit helper in the focused Text namespace.

BREAKING CHANGE: CanonicalFloatingPointFormatter has been removed. Use CanonicalTextFormatter for Double and Single canonical formatting.

Closes #70

Handle empty UTF-16 input consistently across package assets and keep UTF-8 capacity checks atomic for every representable span. Assert fixed-buffer invariants, consolidate unreachable failure paths, and extend the shared canonical corpus with empty text and negative scaled decimals.

Signed-off-by: Kenny Pflug <kenny.pflug@live.de>