[WIP] Fix SFC template suggestions after Volar upgrade

[Copilot]

Thanks for assigning this issue to me. I'm starting to work on it and will keep this PR's description up to date as I form a plan and make progress.

Original prompt

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This section details on the original issue you should resolve

<issue_title>After upgrading to Volar 3.1.6, suggestions stop working in the SFC template. But if I trigger suggestions in the script block first, the template starts working again.</issue_title>
<issue_description>### Vue - Official extension or vue-tsc version

since 3.1.6

VSCode version

1.106.3

Vue version

3.5.25

TypeScript version

5.9.3

System Info

System:
    OS: Windows 11 10.0.28000
    CPU: (16) x64 Intel(R) Core(TM) i7-10700KF CPU @ 3.80GHz
    Memory: 79.50 GB / 127.92 GB
  Binaries:
    Node: 24.11.1 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.22 - C:\Program Files (x86)\Yarn\bin\yarn.CMD
    npm: 11.6.4 - C:\Program Files\nodejs\npm.CMD
    pnpm: 10.12.1 - C:\Users\zhours\AppData\Local\pnpm\pnpm.CMD
  Browsers:
    Chrome: 143.0.7499.41
    Edge: Chromium (143.0.3650.7)
    Firefox: 145.0.2 - C:\Program Files\Mozilla Firefox\firefox.exe

package.json dependencies

{
  "name": "vite-project",
  "private": true,
  "version": "0.0.0",
  "type": "module",
  "scripts": {
    "dev": "vite",
    "build": "vue-tsc -b && vite build",
    "preview": "vite preview"
  },
  "dependencies": {
    "vue": "^3.5.24"
  },
  "devDependencies": {
    "@types/node": "^24.10.1",
    "@vitejs/plugin-vue": "^6.0.1",
    "@vue/tsconfig": "^0.8.1",
    "typescript": "~5.9.3",
    "vite": "npm:[email protected]",
    "vue-tsc": "^3.1.4"
  },
  "pnpm": {
    "overrides": {
      "vite": "npm:[email protected]"
    }
  }
}

Steps to reproduce

2025-12-08.130227.mp4

What is expected?

make code suggestions work in template block

What is actually happening?

suggestions stop working in the SFC template

Link to minimal reproduction

No response

Any additional comments?

No response</issue_description>

Comments on the Issue (you are @copilot in this section)

@serkodev Related to 15cc24e, working on it

• Fixes After upgrading to Volar 3.1.6, suggestions stop working in the SFC template. But if I trigger suggestions in the script block first, the template starts working again. #5822

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