fix(llmobs): apply tracer.set_tags() tags to LLM Observability spans

[FouadWahabi]

Description

LLM Obs span tags were seeded from config.tags (DD_TAGS only), so tags added with tracer.set_tags() reached APM spans but not LLM Obs spans. Seed from tracer._tags instead, which already includes DD_TAGS.

Testing

Added test_tracer_set_tags_applied_to_llmobs_spans. Also verified end-to-end in staging with a pydantic-ai app.

Risks

LLM Obs spans now also carry tags from tracer.set_tags(), same as APM spans.

[cit-pr-commenter-54b7da]

Codeowners resolved as

Resolved from the full PR diff against main using the target branch CODEOWNERS file.
CODEOWNERS team requests not listed below are not required by the current file set.

ddtrace/llmobs/_llmobs.py                                               @DataDog/ml-observability
releasenotes/notes/llmobs-tracer-set-tags-fae850aeca55cdb5.yaml         @DataDog/apm-python
tests/llmobs/test_llmobs_service.py                                     @DataDog/ml-observability

[cit-pr-commenter-54b7da]

Circular import analysis

⚠️ Existing circular imports

There are 1 circular imports that already exist on the base branch and have not been changed by this PR.

ddtrace.errortracking._handled_exceptions.bytecode_injector -> ddtrace.errortracking._handled_exceptions.callbacks -> ddtrace.errortracking._handled_exceptions.collector -> ddtrace.errortracking._handled_exceptions.bytecode_reporting -> ddtrace.errortracking._handled_exceptions.bytecode_injector

[cit-pr-commenter-54b7da]

Dependency direction analysis

⚠️ Existing dependency direction violations

There are 201 dependency direction violations that already exist on the base branch and have not been changed by this PR.

Show existing violations (showing 5 of 201 highest severity)

ddtrace.internal.tracemethods -×-> ddtrace.trace  (internal-core -> product:tracing, score=132)
ddtrace.llmobs._integrations.vertexai -×-> ddtrace.trace  (product:llmobs -> product:tracing, score=130)
ddtrace.internal.test_visibility.api -×-> ddtrace.trace  (product:ci_visibility -> product:tracing, score=130)
ddtrace.llmobs._integrations.google_adk -×-> ddtrace.trace  (product:llmobs -> product:tracing, score=130)
ddtrace.appsec._listeners -×-> ddtrace.trace  (product:appsec -> product:tracing, score=130)

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

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

[FouadWahabi]

/merge

[gh-worker-devflow-routing-ef8351]

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2026-09-30 20:08:27 UTC ℹ️ Start processing command /merge

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2026-09-30 20:08:30 UTC ❌ MergeQueue

The base branch of this pull request is currently frozen (see incident #61179).

If you need to change something else, your pull request can still be merged by commenting /merge -p incident.

[FouadWahabi]

/merge

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-10-01 12:58:37 UTC ℹ️ Start processing command /merge

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2026-10-01 12:58:41 UTC ❌ MergeQueue

The base branch of this pull request is currently frozen (see incident #61179).

If you need to change something else, your pull request can still be merged by commenting /merge -p incident.

[FouadWahabi]

/merge

[gh-worker-devflow-routing-ef8351]

View all feedbacks in Devflow UI.

2026-10-06 21:10:30 UTC ℹ️ Start processing command /merge

---

2026-10-06 21:10:33 UTC ❌ MergeQueue

The base branch of this pull request is currently frozen (see incident #61179).

If you need to change something else, your pull request can still be merged by commenting /merge -p incident.

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-06T21:14:00.474160Z	6a59d12	New commits

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