go.opentelemetry.io/otel/trace v1.44.0: TraceIDFromHex, SpanIDFromHex, NewSpanContext

# OpenTelemetry Go Trace Package Verification

## Search Known Solution Result
- `search_known_solution` returned REVERIFY / COMPATIBLE candidates for older versions (v1.24.0, v1.35.0, v1.45.0) and different OS/libc environments (musl/Alpine vs linux glibc).
- This sample provides verified clean-room coverage for `go.opentelemetry.io/otel/trace@v1.44.0`.

## Verified Contract
1. `trace.TraceIDFromHex` parses valid 32-character lowercase hex strings into a valid `TraceID` and rejects non-32 length inputs, uppercase hex characters, non-hex strings, and all-zero trace IDs.
2. `trace.SpanIDFromHex` parses valid 16-character lowercase hex strings into a valid `SpanID` and rejects non-16 length inputs, uppercase hex characters, non-hex strings, and all-zero span IDs.
3. `trace.NewSpanContext` constructs an immutable `SpanContext`. `sc.IsValid()` requires both `HasTraceID()` and `HasSpanID()` to be true; omitting either or providing an all-zero ID yields an invalid `SpanContext`.
4. `trace.TraceFlags.WithSampled` toggles the sampling bit (`FlagsSampled`) while `IsSampled()` accurately reports sampling status and `String()` formats as two-character hex.
5. `SpanContext` methods `WithRemote`, `WithTraceFlags`, `WithTraceID`, and `WithSpanID` return new modified copies preserving immutability of the original instance, and `Equal` verifies value equality.
6. `trace.ContextWithSpanContext` injects `SpanContext` into a `context.Context` and `trace.SpanContextFromContext` extracts it correctly.

## Pinned Release
- `go.opentelemetry.io/otel/trace v1.44.0`
- `go.opentelemetry.io/otel v1.44.0`

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 pkg:golang/go.opentelemetry.io/otel/trace@v1.44.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:golang/go.opentelemetry.io/otel/trace@v1.44.0
Required runtime conditions:
  - ecosystem: golang
  - language: go
  - packageManager: go@1.26.6
  - runtime: go@1.26.6

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:sha256:3ab38af913494cfae7dd5bcea3edb58acf6d61fe701679c25196d6a1b429f089","contract":["TraceIDFromHex parses valid 32-character lowercase hex while rejecting non-32 length, uppercase hex, and all-zero trace ID","SpanIDFromHex parses valid 16-character lowercase hex while rejecting non-16 length, uppercase hex, and all-zero span ID","NewSpanContext creates SpanContext where IsValid requires both valid TraceID and SpanID, while missing either yields invalid SpanContext","TraceFlags WithSampled toggles sampling bit while IsSampled reports flag status and String formats as two-character hex","SpanContext WithRemote, WithTraceFlags, WithTraceID, and WithSpanID return updated copies preserving immutability of the original","ContextWithSpanContext injects SpanContext into context and SpanContextFromContext retrieves it"],"goal":"verify pkg:golang/go.opentelemetry.io/otel/trace@v1.44.0","kind":"HOW","packages":["pkg:golang/go.opentelemetry.io/otel/trace@v1.44.0"],"schemaVersion":1,"symbols":["go.opentelemetry.io/otel/trace.TraceIDFromHex","go.opentelemetry.io/otel/trace.SpanIDFromHex","go.opentelemetry.io/otel/trace.NewSpanContext","go.opentelemetry.io/otel/trace.SpanContext","go.opentelemetry.io/otel/trace.ContextWithSpanContext"]},"contractCommand":["go","run","./test"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"golang","language":"go","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"go","packageManagerVersion":"1.26.6","runtime":"go","runtimeVersion":"1.26.6","schemaVersion":1},"license":"MIT-0","packages":["pkg:golang/go.opentelemetry.io/otel/trace@v1.44.0"],"schemaVersion":1,"subject":"pkg:golang/go.opentelemetry.io/otel/trace@v1.44.0","symbols":["go.opentelemetry.io/otel/trace.TraceIDFromHex","go.opentelemetry.io/otel/trace.SpanIDFromHex","go.opentelemetry.io/otel/trace.NewSpanContext","go.opentelemetry.io/otel/trace.SpanContext","go.opentelemetry.io/otel/trace.ContextWithSpanContext"],"verifierAdapter":"golang@1"}

module sample

go 1.26.6

require go.opentelemetry.io/otel/trace v1.44.0

require (
	github.com/cespare/xxhash/v2 v2.3.0 // indirect
	go.opentelemetry.io/otel v1.44.0 // indirect
)

github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
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 v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
github.com/stretchr/testify v1.11.1/go.mod h1:wZwfW3scLgRK+23gO65QZefKpKQRnfz6sD981Nm4B6U=
go.opentelemetry.io/otel v1.44.0 h1:JjwHmHpA4iZ3wBxluu2fbbE7j4kqlE8jXyAyPXH7HqU=
go.opentelemetry.io/otel v1.44.0/go.mod h1:BMgjTHL9WPRlRjL2oZCBTL4whCGtXch2H4BhOPIAyYc=
go.opentelemetry.io/otel/trace v1.44.0 h1:jxF5CsGYCe74MCRx2X4g7WsY/VBKRqqpNvXlX/6gtIk=
go.opentelemetry.io/otel/trace v1.44.0/go.mod h1:oLl1jrMQAVo6v3GAggN+1VH9VIz9iUSvW53sW1Q8PIE=
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 pkg:golang/go.opentelemetry.io/otel/trace@v1.44.0",
  "kind": "HOW",
  "packages": [
    "pkg:golang/go.opentelemetry.io/otel/trace@v1.44.0"
  ],
  "symbols": [
    "go.opentelemetry.io/otel/trace.TraceIDFromHex",
    "go.opentelemetry.io/otel/trace.SpanIDFromHex",
    "go.opentelemetry.io/otel/trace.NewSpanContext",
    "go.opentelemetry.io/otel/trace.SpanContext",
    "go.opentelemetry.io/otel/trace.ContextWithSpanContext"
  ],
  "runtimeConditions": {
    "ecosystem": "golang",
    "language": "go",
    "packageManager": "go@1.26.6",
    "runtime": "go@1.26.6"
  }
}

package main

import (
	"context"
	"fmt"
	"os"

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

func main() {
	if err := runTests(); err != nil {
		fmt.Fprintf(os.Stderr, "Contract test failed: %v\n", err)
		os.Exit(1)
	}
	fmt.Println("All OpenTelemetry otel/trace contract tests passed successfully.")
}

func runTests() error {
	// 1. TraceIDFromHex parses valid 32-character lowercase hex while rejecting non-32 length, uppercase hex, and all-zero trace ID
	validTraceHex := "4bf92f3577b34da6a3ce929d0e0e4736"
	tid, err := trace.TraceIDFromHex(validTraceHex)
	if err != nil {
		return fmt.Errorf("TraceIDFromHex failed on valid hex: %w", err)
	}
	if !tid.IsValid() {
		return fmt.Errorf("expected valid TraceID")
	}
	if tid.String() != validTraceHex {
		return fmt.Errorf("expected TraceID String %q, got %q", validTraceHex, tid.String())
	}

	for _, invalidLen := range []string{"", "4bf9", "4bf92f3577b34da6a3ce929d0e0e473", "4bf92f3577b34da6a3ce929d0e0e473600"} {
		if _, err := trace.TraceIDFromHex(invalidLen); err == nil {
			return fmt.Errorf("expected TraceIDFromHex to reject invalid length %q", invalidLen)
		}
	}
	if _, err := trace.TraceIDFromHex("4BF92F3577B34DA6A3CE929D0E0E4736"); err == nil {
		return fmt.Errorf("expected TraceIDFromHex to reject uppercase hex string")
	}
	if _, err := trace.TraceIDFromHex("4bf92f3577b34da6a3ce929d0e0e473z"); err == nil {
		return fmt.Errorf("expected TraceIDFromHex to reject non-hex character")
	}
	if _, err := trace.TraceIDFromHex("00000000000000000000000000000000"); err == nil {
		return fmt.Errorf("expected TraceIDFromHex to reject all-zero trace ID")
	}

	// 2. SpanIDFromHex parses valid 16-character lowercase hex while rejecting non-16 length, uppercase hex, and all-zero span ID
	validSpanHex := "00f067aa0ba902b7"
	sid, err := trace.SpanIDFromHex(validSpanHex)
	if err != nil {
		return fmt.Errorf("SpanIDFromHex failed on valid hex: %w", err)
	}
	if !sid.IsValid() {
		return fmt.Errorf("expected valid SpanID")
	}
	if sid.String() != validSpanHex {
		return fmt.Errorf("expected SpanID String %q, got %q", validSpanHex, sid.String())
	}

	for _, invalidLen := range []string{"", "00f0", "00f067aa0ba902b", "00f067aa0ba902b700"} {
		if _, err := trace.SpanIDFromHex(invalidLen); err == nil {
			return fmt.Errorf("expected SpanIDFromHex to reject invalid length %q", invalidLen)
		}
	}
	if _, err := trace.SpanIDFromHex("00F067AA0BA902B7"); err == nil {
		return fmt.Errorf("expected SpanIDFromHex to reject uppercase hex string")
	}
	if _, err := trace.SpanIDFromHex("00f067aa0ba902bg"); err == nil {
		return fmt.Errorf("expected SpanIDFromHex to reject non-hex character")
	}
	if _, err := trace.SpanIDFromHex("0000000000000000"); err == nil {
		return fmt.Errorf("expected SpanIDFromHex to reject all-zero span ID")
	}

	// 3. NewSpanContext creates SpanContext where IsValid requires both valid TraceID and SpanID, while missing either yields invalid SpanContext
	scValid := trace.NewSpanContext(trace.SpanContextConfig{
		TraceID: tid,
		SpanID:  sid,
	})
	if !scValid.IsValid() {
		return fmt.Errorf("expected SpanContext with valid TraceID and SpanID to be valid")
	}
	if !scValid.HasTraceID() || !scValid.HasSpanID() {
		return fmt.Errorf("expected HasTraceID and HasSpanID to both be true")
	}
	if scValid.TraceID() != tid || scValid.SpanID() != sid {
		return fmt.Errorf("TraceID or SpanID mismatch in SpanContext")
	}

	scNoTrace := trace.NewSpanContext(trace.SpanContextConfig{SpanID: sid})
	if scNoTrace.IsValid() || scNoTrace.HasTraceID() || !scNoTrace.HasSpanID() {
		return fmt.Errorf("expected scNoTrace to be invalid and missing TraceID")
	}

	scNoSpan := trace.NewSpanContext(trace.SpanContextConfig{TraceID: tid})
	if scNoSpan.IsValid() || !scNoSpan.HasTraceID() || scNoSpan.HasSpanID() {
		return fmt.Errorf("expected scNoSpan to be invalid and missing SpanID")
	}

	// 4. TraceFlags WithSampled toggles sampling bit while IsSampled reports flag status and String formats as two-character hex
	var flags trace.TraceFlags
	if flags.IsSampled() || flags.String() != "00" {
		return fmt.Errorf("expected zero TraceFlags to not be sampled and formatted as '00'")
	}
	sampledFlags := flags.WithSampled(true)
	if !sampledFlags.IsSampled() || sampledFlags != trace.FlagsSampled || sampledFlags.String() != "01" {
		return fmt.Errorf("expected sampledFlags to be sampled, match FlagsSampled, and formatted as '01'")
	}
	clearedFlags := sampledFlags.WithSampled(false)
	if clearedFlags.IsSampled() || clearedFlags.String() != "00" {
		return fmt.Errorf("expected clearedFlags to not be sampled and formatted as '00'")
	}

	// 5. SpanContext WithRemote, WithTraceFlags, WithTraceID, and WithSpanID return updated copies preserving immutability of the original
	tid2, _ := trace.TraceIDFromHex("0123456789abcdef0123456789abcdef")
	sid2, _ := trace.SpanIDFromHex("abcdef0123456789")

	origSC := trace.NewSpanContext(trace.SpanContextConfig{
		TraceID: tid,
		SpanID:  sid,
	})
	remoteSC := origSC.WithRemote(true)
	if !remoteSC.IsRemote() || origSC.IsRemote() {
		return fmt.Errorf("WithRemote did not preserve immutability or set Remote correctly")
	}

	flagSC := origSC.WithTraceFlags(trace.FlagsSampled)
	if !flagSC.IsSampled() || origSC.IsSampled() {
		return fmt.Errorf("WithTraceFlags did not preserve immutability or set Flags correctly")
	}

	traceSC := origSC.WithTraceID(tid2)
	if traceSC.TraceID() != tid2 || origSC.TraceID() != tid {
		return fmt.Errorf("WithTraceID did not preserve immutability or set TraceID correctly")
	}

	spanSC := origSC.WithSpanID(sid2)
	if spanSC.SpanID() != sid2 || origSC.SpanID() != sid {
		return fmt.Errorf("WithSpanID did not preserve immutability or set SpanID correctly")
	}

	if !origSC.Equal(trace.NewSpanContext(trace.SpanContextConfig{TraceID: tid, SpanID: sid})) {
		return fmt.Errorf("expected identical SpanContext to be Equal")
	}
	if origSC.Equal(remoteSC) || origSC.Equal(flagSC) || origSC.Equal(traceSC) || origSC.Equal(spanSC) {
		return fmt.Errorf("expected modified copies not to Equal original")
	}

	// 6. ContextWithSpanContext injects SpanContext into context and SpanContextFromContext retrieves it
	ctx := context.Background()
	ctxWithSpan := trace.ContextWithSpanContext(ctx, scValid)
	extractedSC := trace.SpanContextFromContext(ctxWithSpan)
	if !extractedSC.Equal(scValid) {
		return fmt.Errorf("expected extracted SpanContext to match injected SpanContext: got %v, want %v", extractedSC, scValid)
	}

	emptyExtracted := trace.SpanContextFromContext(ctx)
	if emptyExtracted.IsValid() {
		return fmt.Errorf("expected empty SpanContext from background context")
	}

	return nil
}