feat: add lib script validation at run initialization

skills/run/SKILL.md

@@ -63,6 +63,45 @@ After emitting `run.start`, record `SEQ_RUN_START=1`.
 
 If `--start-from` is specified, verify that the required prior artifacts exist in `.archeflow/artifacts/${RUN_ID}/` before skipping phases. If missing, abort with an error.
 
+#### 0a. Lib Script Validation
+
+Verify that all required library scripts exist and are executable before proceeding. Fail fast if any dependency is missing.
+
+```bash
+# Required lib scripts
+REQUIRED_LIBS=(
+  "archeflow-event.sh"
+  "archeflow-memory.sh"
+  "archeflow-git.sh"
+  "archeflow-rollback.sh"
+  "archeflow-report.sh"
+  "archeflow-progress.sh"
+)
+
+MISSING=()
+for lib in "${REQUIRED_LIBS[@]}"; do
+  if [[ ! -x "./lib/$lib" ]]; then
+    MISSING+=("$lib")
+  fi
+done
+
+if [[ ${#MISSING[@]} -gt 0 ]]; then
+  echo "ERROR: Missing or non-executable lib scripts:" >&2
+  for m in "${MISSING[@]}"; do
+    echo "  - lib/$m" >&2
+  done
+  echo "Ensure ArcheFlow is installed correctly. See README for setup." >&2
+  exit 1
+fi
+
+# Check jq availability (required for event processing and memory)
+if ! command -v jq &>/dev/null; then
+  echo "ERROR: jq is required but not found in PATH." >&2
+  echo "Install with: apt install jq / brew install jq" >&2
+  exit 1
+fi
+```
+
 #### 0b. Memory Injection
 
 Load cross-run memory lessons and inject into agent prompts. Use `--audit` to track which lessons were injected for this run: