Adds a canonical reasoning-effort ladder (low|medium|high, absent =
auto/provider default) that travels: send config → turn_created.config →
every model call's persisted parameters (§8.3) → provider-specific
options at invoke time. Behavior-neutral: nothing sends an effort yet,
and auto produces byte-identical requests to today.
- shared: ReasoningEffort enum (single source, reused by models.json
provider config), TurnCreated.config.reasoningEffort (additive
optional on a non-strict object — old builds strip it, no
schemaVersion bump), sessions:sendMessage IPC schema.
- turns: CreateTurnInput/SendMessageConfig/HeadlessAgentOptions carry
the value; runModelStep stamps it on each call's parameters so every
step durably records what it ran with.
- bridge: maps canonical effort to provider options, transport-only
like prompt caching — OpenAI reasoningEffort, Anthropic thinking
budgets (raising maxOutputTokens to the budget floor, never lowering
an explicit value), Gemini thinkingLevel/thinkingBudget by
generation, OpenRouter/rowboat reasoning.effort. Capability-gated
via a cache-only models.dev lookup (never blocks a turn on the
network); unknown support fails closed on strict flavors, while
OpenRouter-shaped flavors map permissively since OpenRouter drops
the field for non-reasoning models. Explicit persisted
providerOptions win over the mapping. Ollama keeps its existing
provider-level think rewrite; openai-compatible endpoints get
nothing (no safe universal parameter).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>