Wait for terminal output to settle (herdr pane idle detection)

herdr-wait-idle

#!/usr/bin/env bash
# Wait for herdr pane output to settle (no changes for N ms)
# Usage: wait-idle <pane-id> [idle-ms] [poll-ms]
#   pane-id: herdr pane ID (e.g., w6B:p2)
#   idle-ms: exit after this many ms of no changes (default: 200)
#   poll-ms: how often to check (default: same as idle-ms)

set -euo pipefail

PANE_ID="${1:?Usage: wait-idle <pane-id> [idle-ms] [poll-ms]}"
IDLE_MS="${2:-200}"
POLL_MS="${3:-$IDLE_MS}"

# Convert ms to seconds for sleep
IDLE_SEC=$(echo "scale=3; $IDLE_MS / 1000" | bc)
POLL_SEC=$(echo "scale=3; $POLL_MS / 1000" | bc)

LAST_OUTPUT=""
UNCHANGED_SINCE=""

while true; do
    # Read current pane output
    CURRENT=$(herdr pane read "$PANE_ID" --source recent-unwrapped --lines 50 2>/dev/null || echo "")

    NOW=$(date +%s%3N 2>/dev/null || date +%s)

    if [[ "$CURRENT" == "$LAST_OUTPUT" ]]; then
        # No change - check if we've been idle long enough
        if [[ -n "$UNCHANGED_SINCE" ]]; then
            ELAPSED=$((NOW - UNCHANGED_SINCE))
            if [[ $ELAPSED -ge $IDLE_MS ]]; then
                echo "idle"
                exit 0
            fi
        fi
    else
        # Output changed - reset timer
        LAST_OUTPUT="$CURRENT"
        UNCHANGED_SINCE="$NOW"
    fi

    sleep "$POLL_SEC"
done