claude-engineering-plugin/todos/004-complete-p2-deep-merge-mcp-servers.md

status, priority, issue_id, tags, dependencies

status	priority	issue_id	tags	dependencies
pending	p2	004	code-review security data-loss

Deep-merge mcpServers in settings.json instead of replacing

Problem Statement

The Gemini writer replaces the entire mcpServers key in settings.json, silently destroying any existing user MCP servers. The test name says "merges" but it actually replaces.

Findings

• src/targets/gemini.ts line 44: { ...existingSettings, mcpServers: bundle.mcpServers }
• tests/gemini-writer.test.ts line 150: test name says "merges" but asserts replacement

Proposed Solution

Deep-merge mcpServers entries: { ...existingMcp, ...bundle.mcpServers }. Update the test to verify existing servers are preserved alongside new ones.

Acceptance Criteria

• Existing mcpServers entries are preserved when new ones are added
• New entries with same name override existing (not merged at field level)
• Test verifies both old and new servers exist after merge
• All tests pass