fix(mem0-plugin): sanitize marker path, add pre-compact REST backup, fix cross-tool gaps

- Sanitize project_id in onboard marker path (tr '/:' '--') to handle
  slashes from env var overrides
- Fire on_pre_compact.py REST backup from PreCompact hook (was only
  called from Stop hooks — crash before Stop = data loss)
- Source _identity.sh in on_stop_codex.sh and on_stop_cursor.sh so
  MEM0_PROJECT_ID + API key fallback are available
- Note dream --schedule is Claude Code-only (Codex/Cursor lack schedule)

mem0-plugin/scripts/on_pre_compact.sh

@@ -15,6 +15,13 @@ if [ -n "${MEM0_DEBUG:-}" ]; then
   mkdir -p "$HOME/.mem0" && exec 2>>"$HOME/.mem0/hooks.log"
 fi
 
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+INPUT=$(cat)
+
+# Fire REST API transcript backup in background (safety net if agent
+# can't complete the add_memory call before compaction finishes)
+echo "$INPUT" | python3 "$SCRIPT_DIR/on_pre_compact.py" --source=pre-compaction 2>/dev/null &
+
 cat <<'EOF'
 ## CRITICAL: Pre-Compaction Session Summary
 

mem0-plugin/scripts/on_session_start.sh

@@ -79,7 +79,8 @@ echo ""
 
 if [ "$SOURCE" = "startup" ]; then
   # First-run detection: auto-trigger onboarding for new projects
-  _ONBOARD_MARKER="$HOME/.mem0/.onboarded_${MEM0_PROJECT_ID}"
+  _SAFE_PID=$(printf '%s' "$MEM0_PROJECT_ID" | tr '/:' '--')
+  _ONBOARD_MARKER="$HOME/.mem0/.onboarded_${_SAFE_PID}"
   if [ ! -f "$_ONBOARD_MARKER" ]; then
     cat <<'EOF'
 ## Mem0 First Run — Automatic Onboarding

mem0-plugin/scripts/on_stop_codex.sh

@@ -22,6 +22,8 @@ if [ -n "${MEM0_DEBUG:-}" ]; then
 fi
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck source=_identity.sh
+. "$SCRIPT_DIR/_identity.sh"
 
 INPUT=$(cat)
 STOP_HOOK_ACTIVE=$(echo "$INPUT" | jq -r '.stop_hook_active // false' 2>/dev/null || echo "false")

mem0-plugin/scripts/on_stop_cursor.sh

@@ -14,6 +14,8 @@ if [ -n "${MEM0_DEBUG:-}" ]; then
 fi
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+# shellcheck source=_identity.sh
+. "$SCRIPT_DIR/_identity.sh"
 
 INPUT=$(cat)
 

mem0-plugin/skills/mem0-onboard/SKILL.md

@@ -77,7 +77,8 @@ If the script reports an error, show the error message and suggest checking the
 Create a marker file so SessionStart won't re-trigger onboarding next session:
 
 ```bash
-mkdir -p ~/.mem0 && touch ~/.mem0/.onboarded_<active_project_id>
+_SAFE_PID=$(printf '%s' "<active_project_id>" | tr '/:' '--')
+mkdir -p ~/.mem0 && touch ~/.mem0/.onboarded_${_SAFE_PID}
 ```
 
 This is silent — no user-facing output needed.