feat(scripts): merge-mcp.sh — preserves laravel-boost, replaces brain-managed MCP

Uses jq --slurpfile pattern (NOT broken `.[1].mcpServers` form from plan):
  jq --slurpfile brain "$brain_mcp" \
     '.mcpServers = ((.mcpServers // {}) + $brain[0].mcpServers)' "$target"

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/tests/merge-mcp-test.sh

@@ -0,0 +1,73 @@
+#!/usr/bin/env bash
+set -u
+SCRIPT_DIR="$(cd "$(dirname "$0")/.." && pwd)"
+source "$SCRIPT_DIR/lib/common.sh"
+
+FAILURES=0
+assert_eq() {
+    if [ "$1" = "$2" ]; then echo "PASS: $3"; else echo "FAIL: $3 (expected '$1', got '$2')"; FAILURES=$((FAILURES + 1)); fi
+}
+
+# Test 1: user-mode merge — magic replaced, laravel-boost preserved
+tmpdir=$(mktemp -d)
+cp "$SCRIPT_DIR/fixtures/sample-claude-json.json" "$tmpdir/.claude.json"
+cat > "$tmpdir/brain-mcp.json" <<EOF2
+{
+  "mcpServers": {
+    "magic": {
+      "type": "stdio",
+      "command": "cmd",
+      "args": ["/c", "npx", "-y", "@21st-dev/magic@latest", "API_KEY=<<MAGIC_API_KEY>>"]
+    }
+  }
+}
+EOF2
+
+bash "$SCRIPT_DIR/lib/merge-mcp.sh" --mode=user "$tmpdir/.claude.json" "$tmpdir/brain-mcp.json"
+
+# magic args should now contain placeholder
+magic_api_key=$(jq -r '.mcpServers.magic.args[-1]' "$tmpdir/.claude.json")
+assert_eq "API_KEY=<<MAGIC_API_KEY>>" "$magic_api_key" "user-mode: magic API_KEY replaced with placeholder"
+
+# laravel-boost preserved
+lb_cmd=$(jq -r '.mcpServers["laravel-boost"].command' "$tmpdir/.claude.json")
+assert_eq "php" "$lb_cmd" "user-mode: laravel-boost preserved"
+
+# preserveMe key still present (other keys unchanged)
+preserve=$(jq -r '.preserveMe' "$tmpdir/.claude.json")
+assert_eq "yes" "$preserve" "user-mode: other top-level keys preserved"
+
+rm -rf "$tmpdir"
+
+# Test 2: project-mode merge — playwright/github/semgrep added, laravel-boost preserved
+tmpdir=$(mktemp -d)
+cp "$SCRIPT_DIR/fixtures/sample-mcp.json" "$tmpdir/.mcp.json"
+cat > "$tmpdir/brain-mcp.json" <<EOF3
+{
+  "mcpServers": {
+    "playwright": {"command": "npx", "args": ["-y", "@playwright/mcp"]},
+    "github": {"type": "http", "url": "https://api.githubcopilot.com/mcp"},
+    "semgrep": {"command": "npx", "args": ["-y", "semgrep-mcp"]}
+  }
+}
+EOF3
+
+bash "$SCRIPT_DIR/lib/merge-mcp.sh" --mode=project "$tmpdir/.mcp.json" "$tmpdir/brain-mcp.json"
+
+# Should have 4 servers total
+count=$(jq '.mcpServers | length' "$tmpdir/.mcp.json")
+assert_eq "4" "$count" "project-mode: 4 servers after merge"
+
+# laravel-boost preserved
+lb=$(jq -r '.mcpServers["laravel-boost"].command' "$tmpdir/.mcp.json")
+assert_eq "php" "$lb" "project-mode: laravel-boost preserved"
+
+# playwright added
+pw=$(jq -r '.mcpServers.playwright.command' "$tmpdir/.mcp.json")
+assert_eq "npx" "$pw" "project-mode: playwright added"
+
+rm -rf "$tmpdir"
+
+echo "---"
+echo "Failures: $FAILURES"
+exit $FAILURES