Assign default capabilities to Codex custom models

[juliusmarminge]

Summary

• Assigns a default Codex capability set to custom models instead of leaving them uncategorized.
• Reuses the same default capability metadata when resolving provider models from settings and when looking up Codex model capabilities.
• Keeps Codex custom models aligned with the built-in capability shape, including reasoning effort options and fast mode support.

Testing

• Not run (PR content generation only).
• Expected checks for the change: bun fmt, bun lint, bun typecheck, and bun run test.

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Note

Low Risk
Low risk: changes only model metadata used for capability/UI selection, with no impact to auth or external API calls.

Overview
Custom models for codex (and now claudeAgent) are no longer created with capabilities: null; providerModelsFromSettings now requires a default ModelCapabilities and assigns it to all custom model entries.

Both providers add a shared default capabilities constant and use it consistently when (1) building the provider model list from settings and (2) falling back in get*ModelCapabilities when a slug isn’t a built-in model, so custom/unknown models get a populated capability shape (Codex includes reasoning effort levels + fast mode by default).

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Note

Assign default capabilities to Codex and Claude custom models

• Custom models registered via providerModelsFromSettings previously had null capabilities; they now receive a provider-specific default ModelCapabilities object.
• DEFAULT_CODEX_MODEL_CAPABILITIES includes reasoning effort levels (xhigh, high as default, medium, low) and supportsFastMode: true; DEFAULT_CLAUDE_MODEL_CAPABILITIES has empty effort levels and both fast mode flags set to false.
• Both getCodexModelCapabilities and getClaudeModelCapabilities also use these constants as the fallback when a slug doesn't match a built-in model.
• Behavioral Change: custom Codex models now expose reasoning effort controls and fast mode where they previously had no capabilities.

^{Macroscope summarized dc2058e.}

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[macroscopeapp]

Approvability

Verdict: Approved

Small, well-scoped change by the code owner that assigns default capabilities to custom Codex models. The behavioral change is intentional and explicitly stated in the title - custom models now get the same capability options as built-in models rather than null capabilities.

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