fix: preserve malformed YAML configs during MCP install

- Add dream.md to managed ByteRover skill files
- Add regression coverage for skill template enumeration
- Fail YAML MCP writes when existing config is malformed or non-mapping
- Preserve existing YAML bytes instead of overwriting with a fresh config

Author: DatPham-6996

src/server/infra/connectors/mcp/yaml-mcp-config-writer.ts

@@ -91,8 +91,9 @@ export class YamlMcpConfigWriter implements IMcpConfigWriter {
     if (await this.fileService.exists(filePath)) {
       try {
         data = parseYamlAsRecord(await this.fileService.read(filePath))
-      } catch {
-        // File exists but contains invalid/empty YAML — start fresh
+      } catch (error) {
+        const details = error instanceof Error ? error.message : String(error)
+        throw new Error(`Cannot update YAML MCP config at ${filePath}: ${details}`)
       }
     }
 

src/server/infra/connectors/skill/skill-connector-config.ts

@@ -138,6 +138,7 @@ export const SKILL_FILE_NAMES = [
   'review.md',
   'swarm.md',
   'vc.md',
+  'dream.md',
   'history.md',
   'troubleshooting.md',
 ] as const

test/unit/infra/connectors/mcp/yaml-mcp-config-writer.test.ts

@@ -173,19 +173,52 @@ describe('YamlMcpConfigWriter', () => {
       expect(parsed.level1.level2.brv).to.deep.equal(serverConfig)
     })
 
-    it('starts fresh when existing YAML is malformed', async () => {
+    it('throws and preserves existing content when YAML is malformed', async () => {
       const writer = new YamlMcpConfigWriter({
         fileService,
         serverKeyPath: ['mcp_servers', 'brv'],
       })
       const filePath = path.join(testDir, 'config.yaml')
-      await writeFile(filePath, ':\n\t[bad: yaml')
+      const originalContent = ':\n\t[bad: yaml'
+      await writeFile(filePath, originalContent)
       const serverConfig = {command: 'brv'}
 
-      await writer.write(filePath, serverConfig)
+      let error: unknown
+      try {
+        await writer.write(filePath, serverConfig)
+      } catch (error_) {
+        error = error_
+      }
 
-      const parsed = yamlLoad(await readFile(filePath, 'utf8')) as Record<string, Record<string, unknown>>
-      expect(parsed.mcp_servers.brv).to.deep.equal(serverConfig)
+      expect(error).to.be.instanceOf(Error)
+      if (!(error instanceof Error)) throw new Error('Expected write to throw')
+
+      expect(error.message).to.include('Cannot update YAML MCP config')
+      expect(await readFile(filePath, 'utf8')).to.equal(originalContent)
+    })
+
+    it('throws and preserves existing content when YAML root is not a mapping', async () => {
+      const writer = new YamlMcpConfigWriter({
+        fileService,
+        serverKeyPath: ['mcp_servers', 'brv'],
+      })
+      const filePath = path.join(testDir, 'config.yaml')
+      const originalContent = '- a\n- b\n'
+      await writeFile(filePath, originalContent)
+      const serverConfig = {command: 'brv'}
+
+      let error: unknown
+      try {
+        await writer.write(filePath, serverConfig)
+      } catch (error_) {
+        error = error_
+      }
+
+      expect(error).to.be.instanceOf(Error)
+      if (!(error instanceof Error)) throw new Error('Expected write to throw')
+
+      expect(error.message).to.include('Cannot update YAML MCP config')
+      expect(await readFile(filePath, 'utf8')).to.equal(originalContent)
     })
   })
 

test/unit/infra/connectors/skill/skill-connector.test.ts

@@ -1,5 +1,5 @@
 import {expect} from 'chai'
-import {mkdir, readFile, rm, writeFile} from 'node:fs/promises'
+import {mkdir, readdir, readFile, rm, writeFile} from 'node:fs/promises'
 import {tmpdir} from 'node:os'
 import path from 'node:path'
 
@@ -42,6 +42,16 @@ describe('SkillConnector', () => {
     })
   })
 
+  describe('managed skill files', () => {
+    it('should enumerate every skill template markdown file', async () => {
+      const templateFileNames = (await readdir(path.resolve('src/server/templates/skill')))
+        .filter((fileName) => fileName.endsWith('.md'))
+        .sort()
+
+      expect([...SKILL_FILE_NAMES].sort()).to.deep.equal(templateFileNames)
+    })
+  })
+
   describe('getSupportedAgents', () => {
     it('should return agents that support skill connector', () => {
       const agents = skillConnector.getSupportedAgents()