System model overrides popup selection in Plan Mode, built-in Google provider cannot be removed #26353

Description

Description

When using OpenCode Desktop on Windows, the model selected in the popup is ignored in certain modes. A system fallback model (big-pickle / gemma4:e4b) responds instead of the one selected, making the user experience unpredictable.

Additionally, the built-in "Google [environment]" provider cannot be fully removed from the provider list even after:

• Deleting all Google/Gemini environment variables (GEMINI_API_KEY, GOOGLE_GENERATIVE_AI_API_KEY)
• Removing all Google/Gemini provider sections from opencode.json
• Adding various provider IDs to disabled_providers (google, googleai, googlegenai, google-ev, gemini)

The provider only disappears after explicitly adding multiple guessed provider IDs to disabled_providers.

Steps to Reproduce

1. Select a model in the popup (e.g., Big Pickle)
2. Enter Plan Mode
3. Observe that a different model responds (e.g., gemma4:e4b) instead of the selected one
4. Try to remove the built-in "Google [environment]" provider by deleting env vars and config

Expected Behavior

1. The selected model in the popup should respond regardless of the mode (Plan or Build)
2. Built-in providers (like Google [environment]) should have a documented, reliable way to be disabled without guessing provider IDs

Actual Behavior

1. Plan Mode forces a system fallback model, ignoring user popup selection
2. Google [environment] provider persists in the UI even after all related configuration is removed

Environment

• OpenCode Desktop version: [your version]
• Platform: Windows

opencode.json config

{
  "disabled_providers": ["google", "googleai", "googlegenai", "google-ev", "gemini"],
  "provider": {
    "ollama": {
      "name": "Ollama (local)",
      "npm": "@ai-sdk/openai-compatible",
      "options": {
        "baseURL": "http://localhost:11434/v1"
      },
      "models": {
        "gemma4:e4b": { "name": "gemma4:e4b" },
        "qwen3-coder-next:latest": { "name": "qwen3-coder-next:latest" }
      }
    }
  }
}

### Plugins

_No response_

### OpenCode version

1.14.41

### Steps to reproduce

1. Select a model in the popup (e.g., Big Pickle)
2. Enter Plan Mode
3. Observe that a different model responds (e.g., gemma4:e4b) instead of the selected one
4. Try to remove the built-in "Google [environment]" provider by deleting env vars and config

### Screenshot and/or share link

Related Issues
#20725: Custom provider falls back to @ai-sdk/openai in sub-sessions
#19572: Feature request to disable inbuilt providers
#9203: Feature: Support disabled_models config
#12384: Google config provider cannot be disconnected

### Operating System

Windows 11 Pro

### Terminal

PowerShell