fix(settings): disable auto-fallback in default model selection

[zerob13]

Remove automatic model fallback in DefaultModelSettingsSection to prevent unintended model changes when providers load late. Models now only change on explicit user selection.

Summary by CodeRabbit

• Refactor
  • Default model selection now relies exclusively on explicit configuration (providerId + modelId) for chat, assistant, and vision; automatic fallbacks to other available models were removed.
  • Simplified selection flow by eliminating multi-step fallback behavior, ensuring selections reflect only the configured settings.

[coderabbitai]

📝 Walkthrough

Walkthrough

Removed the pickFirstEnabledModel helper and its usages from DefaultModelSettingsSection.vue. Chat, assistant, and vision model selections now use only selectBySetting results; no fallbacks to first-enabled or stored selections remain.

Changes

Cohort / File(s)	Summary
Model Selection Refactor src/renderer/settings/components/common/DefaultModelSettingsSection.vue	Deleted pickFirstEnabledModel and removed fallback logic. syncModelSelections and other selection flows now assign chat, assistant, and vision selections solely from selectBySetting, with vision filtering still applied where relevant.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Suggested labels

codex

Poem

🐰 A helper hopped off into night,
Selects now follow settings' light.
No fallback burrows, choices are clear,
Models aligned — the path is near. 🥕

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title 'fix(settings): disable auto-fallback in default model selection' clearly and specifically describes the main change: removing automatic fallback logic in model selection, which aligns with the PR's core objective of preventing unintended model changes.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Merge Conflict Detection	✅ Passed	✅ No merge conflicts detected when merging into dev

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✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch bugfix/default-model

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No actionable comments were generated in the recent review. 🎉

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[coderabbitai]

Actionable comments posted: 1

🤖 Fix all issues with AI agents

In `@src/renderer/settings/components/common/DefaultModelSettingsSection.vue`:
- Around line 226-230: Prettier formatting failed in
DefaultModelSettingsSection.vue for the lines where chatSelection and
assistantSelection are defined; fix it by running the project formatter (pnpm
run format or prettier --write) to reformat the file so selectBySetting calls
and surrounding whitespace match repository Prettier rules, then re-run CI to
confirm the Prettier violation is resolved before merging.