OTEL telemetry stopped working after auto-update to v2.1.72 with OTEL_LOG_TOOL_DETAILS: 1 and elastic apm 8.*

Bug Description

OpenTelemetry (OTEL) telemetry stopped working after auto-updating to v2.1.72 today. Data was confirmed to be flowing correctly on v2.1.71 (and presumably v2.1.70) but no activity is visible after the upgrade.

Environment

• Claude Code version: 2.1.72 (auto-updated 2026-03-10)
• Previous working version: 2.1.71
• OS: Linux (AWS, kernel 6.17.0-1007-aws)
• OTEL backend: Elastic APM via OTLP HTTP (http/protobuf protocol)

Configuration

The following OTEL environment variables are set in ~/.claude/settings.json (sensitive values redacted):

CLAUDE_CODE_ENABLE_TELEMETRY=1
OTEL_METRICS_EXPORTER=otlp
OTEL_LOGS_EXPORTER=otlp
OTEL_EXPORTER_OTLP_PROTOCOL=http/protobuf
OTEL_EXPORTER_OTLP_ENDPOINT=https://<apm-server>:<port>
OTEL_EXPORTER_OTLP_HEADERS=Authorization=Bearer <token>
OTEL_SERVICE_NAME=claude-code
OTEL_EXPORTER_OTLP_METRICS_TEMPORALITY_PREFERENCE=delta
OTEL_LOG_TOOL_DETAILS=1
OTEL_METRICS_INCLUDE_VERSION=true
NODE_TLS_REJECT_UNAUTHORIZED=0

What was verified

• ✅ OTLP endpoint is reachable (HTTP 200)
• ✅ Bearer token is valid — manual OTLP POST with a real protobuf payload returns 200 with valid ExportLogsServiceResponse
• ✅ Settings look structurally correct (all required env vars present)
• ✅ OTLP exporter class names are identical between v2.1.71 and v2.1.72 (OTLPLogExporter, OTLPMetricExporter)
• ❌ No telemetry data is appearing in the APM backend after upgrade

Suspected cause

The v2.1.72 binary is ~3MB smaller than v2.1.71 (234MB vs 237MB). The changelog mentions "Reduced bundle size by ~510 KB" and "Improved bash command parsing by switching to a native module — faster initialization and no memory leak." It's possible the native module switch changed initialization order, or a dependency change affected OTEL setup.

Reproduction

1. Have OTEL telemetry working on v2.1.71 with OTEL_METRICS_EXPORTER=otlp and OTEL_LOGS_EXPORTER=otlp
2. Allow Claude Code to auto-update to v2.1.72
3. Restart a Claude Code session
4. No telemetry data appears in the OTLP backend

Workaround

Currently testing whether rolling back to v2.1.71 restores telemetry (the binary is still available at ~/.local/share/claude/versions/2.1.71).