feat(context): prototype context-scoped attributes (#8532)

[rooks-ns]

Overview

Implements a prototype of Context-scoped attributes as defined in OTEP #4931 and Issue #8532.
Context-scoped attributes attach OpenTelemetry Attributes directly to in-process Context (via ThreadLocal), allowing Traces, Logs, and synchronous Metrics to automatically inherit them .

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Changes

• API (api:incubator):
  • ContextAttributes.add(Context, Attributes): Stores non-propagating attributes in Context (null/empty safe).
  • ContextAttributes.get(Context): Pipeline/SDK reader; applications treat context attributes as write-only.
• Attribute Precedence: Attributes passed directly to a span, log, or measurement call always override conflicting keys from the context.
• Trace (sdk:trace):
  • Merges before Sampler.shouldSample, enabling attribute-based sampling decisions.
  • setNoParent() preserves ambient context attributes while decoupling the parent span (parentContext = Context.root()).
• Logs (sdk:logs):
  • Merges on emit() into a separate record-level map to prevent attribute leakage across reused LogRecordBuilder calls.
• Metrics (sdk:metrics):
  • Merges synchronously per measurement before view filtering and cardinality limits.
  • Supports bound and unbound instruments across both Cumulative and Delta temporality (BoundLongCounter, BoundDoubleCounter).
  • Disables the canUseRootContext bypass when active to ensure thread-local context lookup.
• Configuration:
  • Disabled by default across all signals.
  • Configured programmatically via Sdk*ProviderUtil.setContextScopedAttributesEnabled and declaratively via the experimental context_scoped_attributes/development flag.

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Verification

• Unit test suites (ContextScopedAttributesSpanTest, ContextScopedAttributesLogTest, ContextScopedAttributesMetricTest) verifying key collision precedence, limits, builder reuse isolation, bound instruments, and setNoParent().
• End-to-end integration test (ContextScopedAttributesIntegrationTest).

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Waiting on the author · refreshed 2026-10-18 12:22 UTC

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[codecov]

Codecov Report

❌ Patch coverage is 91.61290% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.47%. Comparing base (b32298a) to head (657d862).
⚠️ Report is 6 commits behind head on main.

Files with missing lines	Patch %	Lines
...ava/io/opentelemetry/sdk/trace/SdkSpanBuilder.java	81.25%	0 Missing and 3 partials ⚠️
...metry/sdk/logs/internal/SdkLoggerProviderUtil.java	75.00%	2 Missing ⚠️
...try/sdk/metrics/internal/SdkMeterProviderUtil.java	75.00%	2 Missing ⚠️
...etry/sdk/trace/internal/SdkTracerProviderUtil.java	75.00%	2 Missing ⚠️
...io/opentelemetry/sdk/logs/SdkLogRecordBuilder.java	92.30%	0 Missing and 1 partial ⚠️
.../opentelemetry/sdk/metrics/AbstractInstrument.java	50.00%	0 Missing and 1 partial ⚠️
...in/java/io/opentelemetry/sdk/metrics/SdkMeter.java	50.00%	0 Missing and 1 partial ⚠️
...trics/internal/state/SynchronousMetricStorage.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #8947      +/-   ##
============================================
+ Coverage     90.40%   90.47%   +0.06%     
- Complexity    10898    10963      +65     
============================================
  Files          1015     1017       +2     
  Lines         29843    29996     +153     
  Branches       3896     3921      +25     
============================================
+ Hits          26981    27138     +157     
+ Misses         1910     1900      -10     
- Partials        952      958       +6     

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