fix(validation): reject unclosed agent frontmatter

scripts/lint-agents.sh

@@ -96,6 +96,11 @@ lint_file() {
     errors=$((errors + 1))
     return
   fi
+  if ! awk 'NR > 1 && $0 == "---" {found = 1; exit} END {exit !found}' "$file"; then
+    echo "ERROR $file: missing frontmatter closing ---"
+    errors=$((errors + 1))
+    return
+  fi
 
   # Extract frontmatter (between first and second ---)
   local frontmatter

scripts/test-convert-outputs.sh

@@ -174,9 +174,12 @@ def find_desc(obj):
     return None
 
 def frontmatter(text):
-    if not text.startswith("---"): raise ValueError("no frontmatter")
-    parts = text.split("\n---", 1)
-    return yaml.safe_load(parts[0][3:])
+    lines = text.splitlines()
+    if not lines or lines[0] != "---": raise ValueError("no frontmatter")
+    for end in range(1, len(lines)):
+        if lines[end] == "---":
+            return yaml.safe_load("\n".join(lines[1:end]))
+    raise ValueError("missing frontmatter closing ---")
 
 def parsed_desc(path, fmt):
     text = open(path, encoding="utf-8").read()

scripts/test-frontmatter-closing.sh

@@ -0,0 +1,37 @@
+#!/usr/bin/env bash
+# An unclosed source frontmatter must not become a deployable empty persona.
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+FIXTURE="$(mktemp -d "${TMPDIR:-/tmp}/agency-frontmatter-closing.XXXXXX")"
+trap 'rm -rf "$FIXTURE"' EXIT
+
+cat > "$FIXTURE/unclosed.md" <<'EOF'
+---
+name: Broken Agent
+description: This agent is missing its closing frontmatter fence
+color: blue
+# Identity
+# Core Mission
+# Critical Rules
+EOF
+
+if bash "$SCRIPT_DIR/lint-agents.sh" "$FIXTURE/unclosed.md" > "$FIXTURE/invalid.log" 2>&1; then
+  echo "linter accepted an agent with no closing frontmatter fence" >&2
+  exit 1
+fi
+grep -Fq 'missing frontmatter closing ---' "$FIXTURE/invalid.log"
+
+cat > "$FIXTURE/valid.md" <<'EOF'
+---
+name: Valid Agent
+description: This agent has a closing frontmatter fence
+color: blue
+---
+## Identity
+## Core Mission
+## Critical Rules
+EOF
+bash "$SCRIPT_DIR/lint-agents.sh" "$FIXTURE/valid.md" > "$FIXTURE/valid.log" 2>&1
+
+echo "PASS: unclosed frontmatter is rejected and a valid agent still passes"