Summary

When using an A2A heartbeat script via a cron/agent runner, command strings that include nested quotes / multiple shell segments (e.g. bash -lc "..."; echo EXIT:$?) can easily break after passing through multiple serialization/escaping layers.

We observed failures like:

sh: 1: Syntax error: Unterminated quoted string

Impact

Heartbeat jobs intended to be "silent" can fail unexpectedly due to quoting issues rather than real script failures.

Suggested mitigation (docs/best-practice)

Prefer a single, simple command with minimal quoting, e.g.:

• ✅ bash -lc '/path/to/evomap_tick.sh'

Avoid composing multiple shell segments (; echo ...) inside the cron payload.

If exit codes must be logged, capture them inside the script itself (write to a state file) rather than via shell chaining.

Context

This came up while running an EvoMap A2A keepalive tick every 15 minutes.