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>

src/converters/claude-to-gemini.ts

@@ -1,6 +1,6 @@
 import { formatFrontmatter } from "../utils/frontmatter"
 import type { ClaudeAgent, ClaudeCommand, ClaudeMcpServer, ClaudePlugin } from "../types/claude"
-import type { GeminiBundle, GeminiCommand, GeminiSkill } from "../types/gemini"
+import type { GeminiBundle, GeminiCommand, GeminiMcpServer, GeminiSkill } from "../types/gemini"
 import type { ClaudeToOpenCodeOptions } from "./claude-to-opencode"
 
 export type ClaudeToGeminiOptions = ClaudeToOpenCodeOptions
@@ -109,12 +109,12 @@ export function transformContentForGemini(body: string): string {
 
 function convertMcpServers(
   servers?: Record<string, ClaudeMcpServer>,
-): GeminiBundle["mcpServers"] | undefined {
+): Record<string, GeminiMcpServer> | undefined {
   if (!servers || Object.keys(servers).length === 0) return undefined
 
-  const result: NonNullable<GeminiBundle["mcpServers"]> = {}
+  const result: Record<string, GeminiMcpServer> = {}
   for (const [name, server] of Object.entries(servers)) {
-    const entry: NonNullable<GeminiBundle["mcpServers"]>[string] = {}
+    const entry: GeminiMcpServer = {}
     if (server.command) {
       entry.command = server.command
       if (server.args && server.args.length > 0) entry.args = server.args

src/targets/gemini.ts

@@ -37,11 +37,14 @@ export async function writeGeminiBundle(outputRoot: string, bundle: GeminiBundle
       try {
         existingSettings = await readJson<Record<string, unknown>>(settingsPath)
       } catch {
-        // If existing file is invalid JSON, start fresh
+        console.warn("Warning: existing settings.json could not be parsed and will be replaced.")
       }
     }
 
-    const merged = { ...existingSettings, mcpServers: bundle.mcpServers }
+    const existingMcp = (existingSettings.mcpServers && typeof existingSettings.mcpServers === "object")
+      ? existingSettings.mcpServers as Record<string, unknown>
+      : {}
+    const merged = { ...existingSettings, mcpServers: { ...existingMcp, ...bundle.mcpServers } }
     await writeJson(settingsPath, merged)
   }
 }

src/types/gemini.ts

@@ -13,15 +13,17 @@ export type GeminiCommand = {
   content: string // Full TOML content
 }
 
+export type GeminiMcpServer = {
+  command?: string
+  args?: string[]
+  env?: Record<string, string>
+  url?: string
+  headers?: Record<string, string>
+}
+
 export type GeminiBundle = {
   generatedSkills: GeminiSkill[] // From agents
   skillDirs: GeminiSkillDir[] // From skills (pass-through)
   commands: GeminiCommand[]
-  mcpServers?: Record<string, {
+  mcpServers?: Record<string, GeminiMcpServer>
-    command?: string
-    args?: string[]
-    env?: Record<string, string>
-    url?: string
-    headers?: Record<string, string>
-  }>
 }

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")
   })
 })