go.opentelemetry.io/otel/trace v1.37.0: TraceIDFromHex

# OpenTelemetry Go TraceIDFromHex Verification

## Search Known Solution Result
- `search_known_solution` returned solutions for `v1.24.0` and `v1.45.0`, but none for `pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0`.
- **Why this sample is distinct**: This sample specifically verifies:
  1. `trace.TraceIDFromHex` parses valid 32-character lowercase hex strings into a valid `TraceID` whose `IsValid()` is true and `String()` returns the original hex string.
  2. `trace.TraceIDFromHex` rejects strings whose length is not exactly 32 characters.
  3. `trace.TraceIDFromHex` rejects uppercase hex characters and non-hex characters.
  4. `trace.TraceIDFromHex` rejects all-zero trace IDs per W3C specification.

## Pinned Release
- `go.opentelemetry.io/otel/trace v1.37.0`
- `go.opentelemetry.io/otel v1.37.0`

## Observed Behaviour
1. `TraceIDFromHex` enforces lowercase hexadecimal encoding and exact 32-character length.
2. All-zero values are rejected with an explicit error.

Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify go.opentelemetry.io/otel/trace.TraceIDFromHex in pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0
Demonstrate these symbols/APIs:
  - go.opentelemetry.io/otel/trace.TraceIDFromHex

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.

{"case":{"caseId":"case:sha256:2325a11170f8938f35d755f7537f2cddb38e3f2c3a6192b4adb3beeeefeabb11","contract":["TraceIDFromHex parses valid 32-character lowercase hex while rejecting non-32 length, uppercase hex, and all-zero trace ID"],"goal":"verify go.opentelemetry.io/otel/trace.TraceIDFromHex in pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0"],"schemaVersion":1,"symbols":["go.opentelemetry.io/otel/trace.TraceIDFromHex"]},"contractCommand":["go","test","./..."],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0","symbols":["go.opentelemetry.io/otel/trace.TraceIDFromHex"],"verifierAdapter":"golang@1"}

module sample

go 1.23.0

require go.opentelemetry.io/otel/trace v1.37.0

require go.opentelemetry.io/otel v1.37.0 // indirect

github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
go.opentelemetry.io/otel v1.37.0 h1:9zhNfelUvx0KBfu/gb+ZgeAfAgtWrfHJZcAqFC228wQ=
go.opentelemetry.io/otel v1.37.0/go.mod h1:ehE/umFRLnuLa/vSccNq9oS1ErUlkkK71gMcN34UG8I=
go.opentelemetry.io/otel/trace v1.37.0 h1:HLdcFNbRQBE2imdSEgm/kwqmQj1Or1l/7bW6mxVK7z4=
go.opentelemetry.io/otel/trace v1.37.0/go.mod h1:TlgrlQ+PtQO5XFerSPUYG0JSgGyryXewPGyayAWSBS0=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

{
  "schemaVersion": 1,
  "goal": "verify go.opentelemetry.io/otel/trace.TraceIDFromHex in pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel/trace@v1.37.0"
  ],
  "symbols": [
    "go.opentelemetry.io/otel/trace.TraceIDFromHex"
  ]
}

package sample_test

import (
	"testing"

	"go.opentelemetry.io/otel/trace"
)

func TestTraceIDFromHex(t *testing.T) {
	// Valid 32-character lowercase hex parses successfully
	validHex := "4bf92f3577b34da6a3ce929d0e0e4736"
	tid, err := trace.TraceIDFromHex(validHex)
	if err != nil {
		t.Fatalf("TraceIDFromHex failed on valid hex: %v", err)
	}
	if !tid.IsValid() {
		t.Fatalf("expected valid TraceID")
	}
	if tid.String() != validHex {
		t.Fatalf("expected String() to match input %q, got %q", validHex, tid.String())
	}

	// Rejection: Invalid lengths
	for _, invalidLen := range []string{"", "4bf9", "4bf92f3577b34da6a3ce929d0e0e473", "4bf92f3577b34da6a3ce929d0e0e473600"} {
		if _, err := trace.TraceIDFromHex(invalidLen); err == nil {
			t.Fatalf("expected TraceIDFromHex to reject invalid length string %q", invalidLen)
		}
	}

	// Rejection: Uppercase hex characters
	uppercaseHex := "4BF92F3577B34DA6A3CE929D0E0E4736"
	if _, err := trace.TraceIDFromHex(uppercaseHex); err == nil {
		t.Fatalf("expected TraceIDFromHex to reject uppercase hex string")
	}

	// Rejection: Non-hex characters
	nonHex := "4bf92f3577b34da6a3ce929d0e0e473z"
	if _, err := trace.TraceIDFromHex(nonHex); err == nil {
		t.Fatalf("expected TraceIDFromHex to reject non-hex character")
	}

	// Rejection: All-zero trace ID
	zeroHex := "00000000000000000000000000000000"
	if _, err := trace.TraceIDFromHex(zeroHex); err == nil {
		t.Fatalf("expected TraceIDFromHex to reject all-zero trace ID")
	}
}