feat: add post-install script and troubleshooting guide

Add scripts/post-install.sh to clear stale skillsSnapshot cache from
existing sessions, ensuring the skill loads immediately after install.
Update README with corrected install path and post-install instructions.
Include detailed troubleshooting report documenting the snapshot cache
root cause analysis.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

scripts/post-install.sh

@@ -0,0 +1,71 @@
+#!/usr/bin/env bash
+# post-install.sh — Flush stale skill snapshots after installing memory-continuity
+#
+# OpenClaw caches a "skillsSnapshot" per session. If this skill was installed
+# while the gateway was stopped (or after a gateway restart), the file watcher
+# won't detect the new SKILL.md and existing sessions will never refresh.
+#
+# This script clears stale snapshots so every session rebuilds on next turn.
+#
+# Usage:
+#   bash scripts/post-install.sh [--agent-id <id>]
+#
+# Options:
+#   --agent-id <id>   Agent ID (default: main)
+#
+# Safe to run multiple times (idempotent).
+
+set -euo pipefail
+
+AGENT_ID="main"
+while [[ $# -gt 0 ]]; do
+  case "$1" in
+    --agent-id) AGENT_ID="$2"; shift 2 ;;
+    *) echo "Unknown option: $1" >&2; exit 1 ;;
+  esac
+done
+
+OPENCLAW_DIR="${OPENCLAW_STATE_DIR:-$HOME/.openclaw}"
+SESSIONS_FILE="$OPENCLAW_DIR/agents/$AGENT_ID/sessions/sessions.json"
+
+if [[ ! -f "$SESSIONS_FILE" ]]; then
+  echo "No sessions file found at $SESSIONS_FILE — nothing to do."
+  exit 0
+fi
+
+# Count and clear stale skillsSnapshot entries
+BEFORE=$(python3 -c "
+import json, sys
+with open('$SESSIONS_FILE') as f:
+    data = json.load(f)
+count = sum(1 for v in data.values() if isinstance(v, dict) and 'skillsSnapshot' in v)
+print(count)
+" 2>/dev/null || echo "0")
+
+if [[ "$BEFORE" == "0" ]]; then
+  echo "No stale skill snapshots found — all sessions will discover skills normally."
+  exit 0
+fi
+
+python3 -c "
+import json
+path = '$SESSIONS_FILE'
+with open(path) as f:
+    data = json.load(f)
+for key in data:
+    if isinstance(data[key], dict) and 'skillsSnapshot' in data[key]:
+        del data[key]['skillsSnapshot']
+with open(path, 'w') as f:
+    json.dump(data, f, indent=2)
+"
+
+echo "Cleared skillsSnapshot from $BEFORE session(s) in $SESSIONS_FILE"
+echo "All sessions will rebuild their skill list on next turn."
+
+# Restart gateway if running, so file watcher picks up the new SKILL.md
+if command -v openclaw &>/dev/null; then
+  if openclaw gateway status 2>&1 | grep -q "running"; then
+    echo "Restarting gateway to activate file watcher..."
+    openclaw gateway restart 2>/dev/null && echo "Gateway restarted." || echo "Gateway restart failed — try manually: openclaw gateway restart"
+  fi
+fi