log-agent.sh

#!/bin/bash
# OpenCode SubagentStart hook: Log agent invocations for audit trail
# Tracks which agents are being used and when
#
# Input schema (SubagentStart) — per OpenCode hooks reference:
# { "session_id": "...", "agent_id": "agent-abc123", "agent_type": "Explore", ... }
#
# The agent name is in `agent_type`, NOT `agent_name`. Reading `.agent_name`
# returns null on every invocation, so the fallback "unknown" is always used
# and the audit trail captures nothing useful.

INPUT=$(cat)

# Parse agent name -- use jq if available, fall back to grep
if command -v jq >/dev/null 2>&1; then
    AGENT_NAME=$(echo "$INPUT" | jq -r '.agent_type // "unknown"' 2>/dev/null)
else
    AGENT_NAME=$(echo "$INPUT" | grep -oE '"agent_type"[[:space:]]*:[[:space:]]*"[^"]*"' | sed 's/"agent_type"[[:space:]]*:[[:space:]]*"//;s/"$//')
    [ -z "$AGENT_NAME" ] && AGENT_NAME="unknown"
fi

TIMESTAMP=$(date +%Y%m%d_%H%M%S)
SESSION_LOG_DIR="production/session-logs"

mkdir -p "$SESSION_LOG_DIR" 2>/dev/null

echo "$TIMESTAMP | Agent invoked: $AGENT_NAME" >> "$SESSION_LOG_DIR/agent-audit.log" 2>/dev/null

exit 0