diff --git a/mcp/install-mcp.sh b/mcp/install-mcp.sh
index c66a23f..97c948e 100755
--- a/mcp/install-mcp.sh
+++ b/mcp/install-mcp.sh
@@ -29,10 +29,60 @@ if [[ "${1:-}" == "--help" || "${1:-}" == "-h" || "${1:-}" == "help" ]]; then
   echo ""
   echo "Builds the prospector MCP package and registers it (name: 'prospector')"
   echo "in Claude Desktop + global ~/.claude/mcp-config.json."
+  echo ""
+  echo "Anti-spam — vendor imessage MCP replacement (opt-in):"
+  echo "  --replace-imessage   neuter the official imessage@claude-plugins-official MCP"
+  echo "                       (raw chat.db/AppleScript send that BYPASSES the prospector"
+  echo "                       send-guard) and route its 'imessage' server through the"
+  echo "                       guarded prospector MCP via a symlink. Reversible."
+  echo "  --restore-imessage   undo the above (restore the vendor .mcp.json, drop the symlink)"
+  echo "  REPLACE_VENDOR_IMESSAGE=1   env equivalent of --replace-imessage"
+  echo "  VENDOR_IMESSAGE_ROOT=...    override the plugin path (auto-detected by default)"
+  echo ""
   echo "See docs/features/mcp.md for full instructions."
   exit 0
 fi
 
+# --- vendor imessage replacement flags (anti-spam) -------------------------
+# The official imessage plugin reads chat.db + sends via AppleScript directly,
+# bypassing ComposeService.send and its duplicate-send guard. These flags let
+# the installer neuter that raw MCP at its source and point the 'imessage'
+# server name at the guarded prospector MCP instead (covers every agent that
+# enables the plugin, regardless of per-agent settings.json).
+REPLACE_VENDOR_IMESSAGE="${REPLACE_VENDOR_IMESSAGE:-0}"
+RESTORE_VENDOR_IMESSAGE=0
+for _arg in "$@"; do
+  case "$_arg" in
+    --replace-imessage) REPLACE_VENDOR_IMESSAGE=1 ;;
+    --restore-imessage) RESTORE_VENDOR_IMESSAGE=1 ;;
+  esac
+done
+VENDOR_IMESSAGE_ROOT="${VENDOR_IMESSAGE_ROOT:-$HOME/.claude/plugins/marketplaces/claude-plugins-official/external_plugins/imessage}"
+
+restore_vendor_imessage() {
+  local root="$VENDOR_IMESSAGE_ROOT"
+  if [ ! -d "$root" ]; then
+    echo "    vendor imessage plugin not found at $root — nothing to restore"
+    return 0
+  fi
+  if [ -f "$root/.mcp.json.orig" ]; then
+    mv -f "$root/.mcp.json.orig" "$root/.mcp.json"
+    echo "    ✅ restored original $root/.mcp.json"
+  else
+    echo "    (no .mcp.json.orig backup found — leaving $root/.mcp.json as-is)"
+  fi
+  rm -f "$root/.prospector-mcp.js"
+  echo "    removed prospector symlink shim (if any)"
+}
+
+# Restore is standalone — it needs no build/secrets, so handle and exit early.
+if [ "$RESTORE_VENDOR_IMESSAGE" = "1" ]; then
+  echo "==> restoring vendor imessage MCP (undo --replace-imessage)"
+  restore_vendor_imessage
+  echo "✅ done. Restart Claude Desktop / sessions to pick up the original imessage MCP."
+  exit 0
+fi
+
 REPO_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
 MCP_DIST="$REPO_ROOT/@packages/mcp-prospector/dist/index.js"
 
@@ -68,6 +118,59 @@ if [ "$TOKEN" = "devtoken" ]; then
   echo "⚠️  Using devtoken (from .env.local). For production put real token in $VENV"
 fi
 
+# 2.5 Optionally neuter + replace the vendor imessage MCP with the guarded prospector MCP.
+if [ "$REPLACE_VENDOR_IMESSAGE" = "1" ]; then
+  echo "==> replacing vendor imessage MCP with the guarded prospector MCP (anti-spam)"
+  ROOT="$VENDOR_IMESSAGE_ROOT"
+  if [ ! -d "$ROOT" ]; then
+    echo "⚠️  vendor imessage plugin not found at $ROOT — skipping replace."
+    echo "    (set VENDOR_IMESSAGE_ROOT=/path/to/imessage if it lives elsewhere)"
+  else
+    # Preserve the original raw-send MCP config exactly once (idempotent re-runs
+    # must not clobber a real original with our already-rewritten copy).
+    if [ -f "$ROOT/.mcp.json" ] && [ ! -f "$ROOT/.mcp.json.orig" ]; then
+      cp "$ROOT/.mcp.json" "$ROOT/.mcp.json.orig"
+      echo "    backed up original  -> $ROOT/.mcp.json.orig"
+    fi
+    # Symlink the prospector MCP dist to a stable path inside the plugin root,
+    # then point the 'imessage' server at it. The symlink is the single thing to
+    # repoint if the repo moves; --restore-imessage removes it.
+    SHIM="$ROOT/.prospector-mcp.js"
+    ln -sf "$MCP_DIST" "$SHIM"
+    echo "    symlinked           $SHIM -> $MCP_DIST"
+    ROOT="$ROOT" NODE="$NODE" SHIM="$SHIM" BASE_URL="$BASE_URL" TOKEN="$TOKEN" python3 - <<'PY'
+import json, os, tempfile
+
+root = os.environ["ROOT"]
+path = os.path.join(root, ".mcp.json")
+cfg = {
+    "mcpServers": {
+        # Keep the server NAME 'imessage' so existing references resolve, but
+        # launch the guarded prospector MCP (send-guard enforced) instead of the
+        # raw chat.db/AppleScript sender.
+        "imessage": {
+            "command": os.environ["NODE"],
+            "args": [os.environ["SHIM"]],
+            "env": {
+                "PROSPECTOR_BASE_URL": os.environ["BASE_URL"],
+                "PROSPECTOR_SERVICE_TOKEN": os.environ["TOKEN"],
+            },
+        }
+    }
+}
+fd, tmp = tempfile.mkstemp(dir=root, suffix=".tmp")
+with os.fdopen(fd, "w") as f:
+    json.dump(cfg, f, indent=2)
+    f.write("\n")
+os.replace(tmp, path)
+print("    ✅ rewrote", path)
+print("       'imessage' MCP now runs the guarded prospector MCP (raw send disabled)")
+PY
+    echo "    ⓘ  Claude re-syncs the marketplace on plugin update — re-run --replace-imessage after updates."
+    echo "    ⓘ  Undo any time with: ./run install:mcp --restore-imessage"
+  fi
+fi
+
 # 3. Safety: quit Claude Desktop if running (so our edit survives its next quit rewrite).
 #    We always proceed with the JSON edits (Desktop will pick them up on next full restart).
 #    Use SKIP_QUIT=1 or NO_RELAUNCH=1 to avoid osascript side effects in automated/CI contexts.