fix: address code review findings for gemini target

- Extract named GeminiMcpServer type (eliminates NonNullable indexing)
- Deep-merge mcpServers in settings.json (preserves existing entries)
- Warn when existing settings.json cannot be parsed
- Add test for uniqueName dedup (agent/skill name collision)
- Add test for TOML triple-quote escaping

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/gemini-converter.test.ts

@@ -267,6 +267,25 @@ describe("convertClaudeToGemini", () => {
     expect(bundle.commands).toHaveLength(0)
   })
 
+  test("agent name colliding with skill name gets deduplicated", () => {
+    const plugin: ClaudePlugin = {
+      ...fixturePlugin,
+      skills: [{ name: "security-reviewer", description: "Existing skill", sourceDir: "/tmp/skill", skillPath: "/tmp/skill/SKILL.md" }],
+      agents: [{ name: "Security Reviewer", description: "Agent version", body: "Body.", sourcePath: "/tmp/agents/sr.md" }],
+      commands: [],
+    }
+
+    const bundle = convertClaudeToGemini(plugin, {
+      agentMode: "subagent",
+      inferTemperature: false,
+      permissions: "none",
+    })
+
+    // Agent should be deduplicated since skill already has "security-reviewer"
+    expect(bundle.generatedSkills[0].name).toBe("security-reviewer-2")
+    expect(bundle.skillDirs[0].name).toBe("security-reviewer")
+  })
+
   test("hooks present emits console.warn", () => {
     const warnings: string[] = []
     const originalWarn = console.warn
@@ -339,4 +358,16 @@ describe("toToml", () => {
     const result = toToml('Say "hello"', "Prompt")
     expect(result).toContain('description = "Say \\"hello\\""')
   })
+
+  test("escapes triple quotes in prompt", () => {
+    const result = toToml("A command", 'Content with """ inside it')
+    // Should not contain an unescaped """ that would close the TOML multi-line string prematurely
+    // The prompt section should have the escaped version
+    expect(result).toContain('description = "A command"')
+    expect(result).toContain('prompt = """')
+    // The inner """ should be escaped
+    expect(result).not.toMatch(/""".*""".*"""/s) // Should not have 3 separate triple-quote sequences (open, content, close would make 3)
+    // Verify it contains the escaped form
+    expect(result).toContain('\\"\\"\\"')
+  })
 })

tests/gemini-writer.test.ts

@@ -173,7 +173,9 @@ describe("writeGeminiBundle", () => {
     const content = JSON.parse(await fs.readFile(settingsPath, "utf8"))
     // Should preserve existing model key
     expect(content.model).toBe("gemini-2.5-pro")
-    // mcpServers should be replaced (not merged) with new content
+    // Should preserve existing MCP server
+    expect(content.mcpServers.old.command).toBe("old-cmd")
+    // Should add new MCP server
     expect(content.mcpServers.newServer.command).toBe("new-cmd")
   })
 })