refactor: remove ExecutionContext._inner_span

[emmettbutler]

This change removes the _inner_span attribute from ddtrace.core.ExecutionContext, replacing it with an _inner_span datum stored via existing mechanisms. This eliminates Spans as a special case in the Core API, treating them like any other piece of data stored in the context tree.

span_bus is introduced containing two of the span-related helper functions from core, indicating the separateness of Span management from Core. Note that while this separation does fix the import-time coupling between _trace and core, it does not address the functional dependence of certain products on _trace, specifically those that use Spans as context tracking.

[datadog-official]

🎉 All green!

🧪 All tests passed
❄️ No new flaky tests detected

🔄 Datadog auto-retried 3 jobs - 2 passed on retry

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🔗 Commit SHA: 683a5f6 | Docs | Datadog PR Page | Give us feedback!}

[cit-pr-commenter-54b7da]

Codeowners resolved as

ddtrace/internal/core/__init__.py                                       @DataDog/apm-core-python

[cit-pr-commenter-54b7da]

Circular import analysis

⚠️ Existing circular imports

There are 42 circular imports that already exist on the base branch and have not been changed by this PR.

Show existing cycles (showing 5 of 42 shortest)

ddtrace.internal.datastreams -> ddtrace.internal.datastreams.botocore -> ddtrace.internal.datastreams
ddtrace.internal.datastreams -> ddtrace.internal.datastreams.kafka -> ddtrace.internal.datastreams
ddtrace.internal.datastreams -> ddtrace.internal.datastreams.aiokafka -> ddtrace.internal.datastreams
ddtrace.internal.datastreams -> ddtrace.internal.datastreams.kombu -> ddtrace.internal.datastreams
ddtrace.internal.datastreams -> ddtrace.internal.datastreams.google_cloud_pubsub -> ddtrace.internal.datastreams

To see all cycles, download the cycles-base.json and cycles-pr.json artifacts from this CI job and run:

uv run --script scripts/import-analysis/cycles.py compare cycles-base.json cycles-pr.json

✅ Circular imports removed

19 circular import(s) have been removed by this PR.

Show removed cycles (showing 5 of 19 shortest)

ddtrace.internal.core -> ddtrace._trace.span -> ddtrace.internal.core
ddtrace.internal.utils -> ddtrace.internal.core -> ddtrace._trace.span -> ddtrace._trace.context -> ddtrace.internal.utils.http -> ddtrace.internal.utils
ddtrace.internal.core -> ddtrace._trace.span -> ddtrace.internal.settings._config -> ddtrace.internal.telemetry -> ddtrace.internal.telemetry.writer -> ddtrace.internal.core
ddtrace.internal.core -> ddtrace._trace.span -> ddtrace._trace._span_pointer -> ddtrace._trace.telemetry -> ddtrace.internal.telemetry -> ddtrace.internal.telemetry.writer -> ddtrace.internal.core
ddtrace.internal.utils -> ddtrace.internal.core -> ddtrace._trace.span -> ddtrace.internal.settings._config -> ddtrace.internal.settings.http -> ddtrace.internal.utils.http -> ddtrace.internal.utils

To see all cycles, download the cycles-base.json and cycles-pr.json artifacts from this CI job and run:

uv run --script scripts/import-analysis/cycles.py compare cycles-base.json cycles-pr.json

[pr-commenter]

Benchmarks

Benchmark execution time: 2026-07-15 19:33:33

Comparing candidate commit 72f665e in PR branch emmett.butler/no-inner-span with baseline commit 7edd95d in branch emmett.butler/no-core-tracer.

Found 0 performance improvements and 5 performance regressions! Performance is the same for 613 metrics, 10 unstable metrics.

scenario:iastaspects-lstrip_aspect

• 🟥 execution_time [+67.393µs; +72.555µs] or [+20.798%; +22.391%]

scenario:iastaspects-repr_aspect

• 🟥 execution_time [+56.101µs; +63.662µs] or [+14.756%; +16.745%]

scenario:iastaspects-translate_aspect

• 🟥 execution_time [+65.680µs; +72.033µs] or [+12.857%; +14.100%]

scenario:iastaspectsospath-ospathbasename_aspect

• 🟥 execution_time [+100.585µs; +107.587µs] or [+24.191%; +25.875%]

scenario:span-start

• 🟥 execution_time [+1.312ms; +1.490ms] or [+8.338%; +9.475%]

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Update remaining ctx.span benchmark callers

Now that span access has moved to span_from_context, the repo still has ctx.span in benchmarks/events_api/scenario.py at lines 53 and 85. When the events_api benchmark runs those handlers after _start_span, ExecutionContext no longer has a span attribute, so the benchmark aborts with AttributeError instead of measuring the refactor. Please update the benchmark callers to use this helper or keep a compatibility alias.

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