ENG-9166 feat(otel): compile spans (2/3)

[FarhanAliRaza]

Part of #6227 (ENG-9166). Stack: 1/3 → 2/3 (this) → 3/3. Base is farhan/eng-9166-reflex-otel (1/3); the diff is one commit.

What

• App._compile runs inside a reflex.compile span (reflex.compile.trigger, reflex.compile.dry_run); the compile stages get explicit child spans in compiler.py: reflex.compile.evaluate_pages, .pages, .copy_assets, .install_frontend_packages, .write.
• otel.span() / otel.compile_span() helpers (no-op nullcontext when disabled; compile is not a hot path).

Log correlation (trace_id/span_id on JSON log records) was split out of this stack: it needs the JsonHandler from the logging pipeline (#6863) and will follow as a small PR once that lands (#6903).

Tests

test_otel.py (span helpers, compile_span attributes/nesting), test_app.py::test_compile_emits_stage_spans (real compile, stages nest under reflex.compile).

[linear-code]

ENG-9166

[greptile-apps]

Greptile Summary

The PR adds OpenTelemetry instrumentation around the full application compilation and its major stages.

• Adds no-op-capable generic and compile-specific span helpers.
• Wraps App._compile in a root compile span with trigger and dry-run attributes.
• Instruments page evaluation, page compilation, asset copying, frontend package installation, and disk writes.
• Adds documentation, changelog entries, and tests for span attributes and parent-child relationships.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

Important Files Changed

Filename	Overview
packages/reflex-base/src/reflex_base/otel.py	Adds generic internal-span and compile-span context managers that become no-ops when tracing is disabled.
reflex/app.py	Wraps the existing compilation and telemetry-accounting flow in a root OpenTelemetry compile span.
reflex/compiler/compiler.py	Adds child spans around five major stages of the existing compilation pipeline.
tests/units/reflex_base/test_otel.py	Tests disabled behavior, compile attributes, and nested span parenting.
tests/units/test_app.py	Verifies that a real application compile emits stage spans parented to the root compile span.

_{Reviews (5): Last reviewed commit: "feat(otel): compile spans" | Re-trigger Greptile}

[codspeed-hq]

Merging this PR will not alter performance

✅ 26 untouched benchmarks
⏩ 8 skipped benchmarks¹

---

_{Comparing farhan/eng-9166-reflex-otel-3 (7427498) with farhan/eng-9166-reflex-otel (2f9b04d)}

Footnotes

1. 8 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[chatgpt-codex-connector]

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[cubic-dev-ai]

All reported issues were addressed across 28 files

<sub>Reply with feedback, questions, or to request a fix.

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[Alek99]

The initial compile trace works locally, but the common backend-startup/stateful-marker path omits one advertised stage.

[Alek99]

[P2] Include the stateful-marker backend evaluation in reflex.compile.evaluate_pages

When .web/backend exists and stateful_pages.json is present, the earlier branch evaluates each marked page with _compile_page(..., save_page=False) and returns at line 1171 before this span is entered. I reproduced that normal backend_startup path with an OTLP exporter: only the reflex.compile root was emitted even though page evaluation ran. Please wrap the marker-driven loop in the same stage span (or factor both paths through a shared helper) and cover the early-return marker path.