modelReasoningEfforts: [] makes routed models unusable as subagents (catalog supported_reasoning_levels empty) #883

What happens

When a routed model (e.g. cursor/composer-2.5) has modelReasoningEfforts: [] (explicit empty array) in config, ocx sync writes supported_reasoning_levels: [] into the Codex catalog. The Codex app then rejects the model for spawn_agent calls because [agents].default_subagent_reasoning_effort = "max" has no valid level to match against the empty list. The request never reaches the proxy, so the model works in the main thread but is unusable as a subagent.

Root cause (located)

src/reasoning-effort.ts, configuredReasoningEfforts:

const modelEfforts = modelRecordValue(provider.modelReasoningEfforts, modelId);
if (modelEfforts !== undefined) return ... [];  // [] is explicit "no reasoning" → catalog []

An explicit [] and an omitted key behave differently. [] produces an empty supported_reasoning_levels in the catalog; an omitted key lets the default ladder fill in. A model that genuinely takes no reasoning effort becomes invisible to the subagent roster.

Expected

Either the [] → empty-list semantics should be documented/preserved consistently, or ocx sync should detect models in the subagent roster whose catalog supported_reasoning_levels is empty and either warn or backfill a placeholder level, so spawn_agent with the global default effort is not silently blocked.

Local workaround (verified)

Remove the composer-2.5: [] entry from modelReasoningEfforts. After ocx sync, the catalog fills in the default ladder and subagent routing works (the cursor adapter already drops the effort suffix for composer at the wire, so the upstream is unaffected).