### Added

- Add `Enabled` method to all synchronous instrument interfaces
(`Float64Counter`, `Float64UpDownCounter`, `Float64Histogram`,
`Float64Gauge`, `Int64Counter`, `Int64UpDownCounter`, `Int64Histogram`,
`Int64Gauge`,) in `go.opentelemetry.io/otel/metric`. This stabilizes the
synchronous instrument enabled feature, allowing users to check if an
instrument will process measurements before performing computationally
expensive operations. (#7763)
- Add `AlwaysRecord` sampler in `go.opentelemetry.io/otel/sdk/trace`.
(#7724)
- Add `go.opentelemetry.io/otel/semconv/v1.39.0` package. The package
contains semantic conventions from the `v1.39.0` version of the
OpenTelemetry Semantic Conventions. See the [migration
documentation](https://github.com/open-telemetry/opentelemetry-go/blob/298cbedf256b7a9ab3c21e41fc5e3e6d6e4e94aa/semconv/v1.39.0/MIGRATION.md)
for information on how to upgrade from
`go.opentelemetry.io/otel/semconv/v1.38.0.` (#7783, #7789)

### Changed

- `Exporter` in `go.opentelemetry.io/otel/exporter/prometheus` ignores
metrics with the scope `go.opentelemetry.io/contrib/bridges/prometheus`.
This prevents scrape failures when the Prometheus exporter is
misconfigured to get data from the Prometheus bridge. (#7688)
- Improve performance of concurrent histogram measurements in
`go.opentelemetry.io/otel/sdk/metric`. (#7474)
- Add experimental observability metrics in
`go.opentelemetry.io/otel/exporters/stdout/stdoutmetric`. (#7492)
- Improve the concurrent performance of `HistogramReservoir` in
`go.opentelemetry.io/otel/sdk/metric/exemplar` by 4x. (#7443)
- Improve performance of concurrent synchronous gauge measurements in
`go.opentelemetry.io/otel/sdk/metric`. (#7478)
- Improve performance of concurrent exponential histogram measurements
in `go.opentelemetry.io/otel/sdk/metric`. (#7702)
- Improve the concurrent performance of `FixedSizeReservoir` in
`go.opentelemetry.io/otel/sdk/metric/exemplar`. (#7447)
- The `rpc.grpc.status_code` attribute in the experimental metrics
emitted from
`go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc` is
replaced with the `rpc.response.status_code` attribute to align with the
semantic conventions. (#7854)
- The `rpc.grpc.status_code` attribute in the experimental metrics
emitted from
`go.opentelemetry.io/otel/exporters/otlp/otlplog/otlploggrpc` is
replaced with the `rpc.response.status_code` attribute to align with the
semantic conventions. (#7854)

### Fixed

- Fix bad log message when key-value pairs are dropped because of key
duplication in `go.opentelemetry.io/otel/sdk/log`. (#7662)
- Fix `DroppedAttributes` on `Record` in
`go.opentelemetry.io/otel/sdk/log` to not count the non-attribute
key-value pairs dropped because of key duplication. (#7662)
- Fix `SetAttributes` on `Record` in `go.opentelemetry.io/otel/sdk/log`
to not log that attributes are dropped when they are actually not
dropped. (#7662)
- `WithHostID` detector in `go.opentelemetry.io/otel/sdk/resource` to
use full path for `ioreg` command on Darwin (macOS). (#7818)
- Fix missing `request.GetBody` in
`go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp` to
correctly handle HTTP2 GOAWAY frame. (#7794)

### Deprecated

- Deprecate `go.opentelemetry.io/otel/exporters/zipkin`. For more
information, see the [OTel blog post deprecating the Zipkin
exporter](https://opentelemetry.io/blog/2025/deprecating-zipkin-exporters/).
(#7670)

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>