Config dependency install can produce orphaned OpenTelemetry spans

Description

When OTel tracing is enabled, child spans from background config dependency installation can be exported without their parent span.

I originally noticed this while inspecting OpenCode traces in Jaeger. In the observed traces, child spans such as FileSystem.existsSafe and EffectFlock.acquire were exported successfully, while their parent spans were missing.

The missing spans came from config dependency work started in src/config/config.ts. The dependency install is launched with Effect.forkDetach, so the fiber can outlive the Config/instance scope that initiated it.

The child spans still had valid parentSpanId values, so this does not appear to be a context propagation issue. Instead, the parent span can remain open in the detached fiber while the surrounding Config/instance lifecycle and telemetry are shutting down.

Plugins

None required to reproduce.

OpenCode version

Reproduced on the current dev branch (8a6cf2c9aa). Originally observed in v1.18.21.

Steps to reproduce

Apply the attached reproducer patch on the current dev branch:

git apply config-fork-lifecycle-repro.patch

bun test test/config/config.test.ts \
  -t "exports the parent span for background config dependency install"

The test fails because the child span is exported while its referenced parent span is missing.

Replacing forkDetach with forkScoped in src/config/config.ts makes the same test pass. If this direction sounds reasonable, I’d be happy to open a PR with the forkScoped change.

Screenshot and/or share link

The screenshot below shows a trace with two missing-parent spans. The attached reproducer provides a deterministic test for the same behavior.

Operating System

NixOS 26.11 (Zokor)

Terminal

Wezterm