fix(fleet): harden managed launch composition

AMD1213-C: repair stale array consumer, fail closed on foreign link provenance, validate manifests before mutation, and exercise the fleet MCP preflight call path.

packages/mosaic/framework/tools/_scripts/mosaic-ensure-sequential-thinking

@@ -86,7 +86,9 @@ config_dir = os.environ.get("CLAUDE_CONFIG_DIR")
 p = Path(config_dir) / ".claude.json" if config_dir else Path.home() / ".claude.json"
 if not p.exists() and not config_dir:
     p = Path.home() / ".claude" / "settings.json"
-if not p.exists():
+# Only explicit fleet seats require a private, non-symlink config. Operator
+# config remains compatible with pre-existing permission conventions.
+if not p.exists() or p.is_symlink() or (config_dir and (p.stat().st_mode & 0o077) != 0):
     raise SystemExit(1)
 try:
     data = json.loads(p.read_text(encoding="utf-8"))
@@ -137,7 +139,7 @@ PY
 }
 
 check_codex_config() {
-  local cfg="$HOME/.codex/config.toml"
+  local cfg="${CODEX_HOME:-$HOME/.codex}/config.toml"
   [[ -f "$cfg" ]] || return 1
   grep -Eq '^\[mcp_servers\.(sequential-thinking|sequential_thinking)\]' "$cfg" && \
   grep -q '^command = "npx"' "$cfg" && \
@@ -145,7 +147,7 @@ check_codex_config() {
 }
 
 apply_codex_config() {
-  local cfg="$HOME/.codex/config.toml"
+  local cfg="${CODEX_HOME:-$HOME/.codex}/config.toml"
   mkdir -p "$(dirname "$cfg")"
   [[ -f "$cfg" ]] || touch "$cfg"
 
@@ -168,10 +170,11 @@ apply_codex_config() {
 }
 
 check_opencode_config() {
-  python3 - <<'PY'
+  XDG_CONFIG_HOME="${XDG_CONFIG_HOME:-}" python3 - <<'PY'
 import json
+import os
 from pathlib import Path
-p = Path.home() / ".config" / "opencode" / "config.json"
+p = Path(os.environ["XDG_CONFIG_HOME"]) / "opencode" / "config.json" if os.environ.get("XDG_CONFIG_HOME") else Path.home() / ".config" / "opencode" / "config.json"
 if not p.exists():
     raise SystemExit(1)
 try:
@@ -194,10 +197,11 @@ PY
 }
 
 apply_opencode_config() {
-  python3 - <<'PY'
+  XDG_CONFIG_HOME="${XDG_CONFIG_HOME:-}" python3 - <<'PY'
 import json
+import os
 from pathlib import Path
-p = Path.home() / ".config" / "opencode" / "config.json"
+p = Path(os.environ["XDG_CONFIG_HOME"]) / "opencode" / "config.json" if os.environ.get("XDG_CONFIG_HOME") else Path.home() / ".config" / "opencode" / "config.json"
 p.parent.mkdir(parents=True, exist_ok=True)
 if p.exists():
     try: