The inline environment variable syntax `TIMESTAMP="$timestamp" echo ...`
does not work correctly because:
1. The pipe creates a subshell that doesn't inherit the variable
2. The environment variable is set for echo, not for the piped python
Fixed by using `export` and separating the commands:
- export TIMESTAMP="$timestamp"
- echo "$INPUT_JSON" | python3 -c "..."
This ensures the TIMESTAMP variable is available to the python subprocess.
Fixes#227
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>