Refactor model ID checks for GPT 5.x model family

[praveentcom]

All GPT-5.x series models don't support minimal as the reasoningEffort. Currently, it is enabled only for GPT-5.1 and GPT-5.2 models to set the reasoningEffort as low. This would start throwing errors like these.

Unsupported value: 'minimal' is not supported with the 'gpt-5.4' model. Supported values are: 'none', 'low', 'medium', 'high', and 'xhigh'.

This PR fixes the behavior to set the reasoning effort as low for all GPT-5.x series models so that we don't need to manually patch it every time when a new SOTA model is released.

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Summary by cubic

Set reasoningEffort to "low" for all GPT-5.x models to prevent unsupported "minimal" errors on new releases like gpt-5.4. Use a precise gpt-5. match (not version-specific) and keep codex excluded, removing the need for manual patches.

^{Written for commit a637dc3. Summary will update on new commits. Review in cubic}

[changeset-bot]

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[github-actions]

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[greptile-apps]

Greptile Summary

This PR refactors the usesLowReasoningEffort guard in AISdkClient so that all gpt-5.x versioned models automatically receive reasoningEffort: "low" instead of the unsupported "minimal" value, eliminating the need to manually add each new GPT-5 sub-version.

Key changes:

• Replaced the explicit gpt-5.1 || gpt-5.2 OR-chain with a single includes("gpt-5.") prefix check, which covers all current and future gpt-5.<version> model IDs.
• The existing !isCodex guard is preserved to keep Codex models on "medium" reasoning effort.

Issues found:

• A model ID of exactly gpt-5 (no version dot) passes the existing isGPT5 = includes("gpt-5") check (triggering the providerOptions branch) but does not pass the new includes("gpt-5.") check, so it would still fall through to reasoningEffort: "minimal" — the unsupported value this PR is trying to eliminate. If OpenAI ever surfaces a bare gpt-5 alias (a common pattern for their "latest" pointer), this would reproduce the original error.

Confidence Score: 3/5

• The PR solves the stated problem for versioned gpt-5.x models but leaves a gap for any bare gpt-5 alias, which would still receive the unsupported "minimal" reasoning effort.
• The core intent is correct and the change is minimal in scope. However, the isGPT5 / usesLowReasoningEffort checks are now misaligned: isGPT5 matches gpt-5 while usesLowReasoningEffort requires gpt-5., meaning a bare gpt-5 model would still trigger the broken "minimal" path that this PR explicitly aims to fix. This is a reproducible logic gap that warrants a fix before merging.
• packages/core/lib/v3/llm/aisdk.ts — the usesLowReasoningEffort condition on lines 137–139

Important Files Changed

Filename	Overview
packages/core/lib/v3/llm/aisdk.ts	Broadened usesLowReasoningEffort from explicit gpt-5.1/gpt-5.2 checks to a gpt-5. prefix match — fixes the immediate problem for versioned models, but leaves a gap for a bare gpt-5 model ID (no version dot), which would still receive the unsupported "minimal" reasoning effort.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[LLM Request with GPT-5 model] --> B{isGPT5?\nincludes 'gpt-5'}
    B -- No --> C[providerOptions: undefined]
    B -- Yes --> D{isCodex?\nincludes 'codex'}
    D -- Yes --> E[textVerbosity: 'medium'\nreasoningEffort: 'medium']
    D -- No --> F{usesLowReasoningEffort?\nincludes 'gpt-5.' AND not codex}
    F -- Yes\ngpt-5.1, gpt-5.4, etc. --> G[textVerbosity: 'low'\nreasoningEffort: 'low']
    F -- No\ne.g. bare 'gpt-5' --> H[textVerbosity: 'low'\nreasoningEffort: 'minimal' ⚠️]
    H --> I[API Error: 'minimal' not supported]

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_{Last reviewed commit: "Fix condition for GP..."}

[cubic-dev-ai]

No issues found across 1 file

Confidence score: 5/5

• Automated review surfaced no issues in the provided summaries.
• No files require special attention.

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[praveentcom]

@greptile review

[github-actions]

This PR was approved by @miguelg719 and mirrored to #1852. All further discussion should happen on that PR.