Use lower thinking/effort for cron and hook sessions under OAuth

[constkolesnyak]

Problem

Every cron run on Claude OAuth (subscription) fails with:

API Error: 400 level "max" not supported, valid levels: low, medium, high

Root cause: the global agent.thinking=max / agent.effort=max defaults are applied to every session, including cron and hook sessions that run on cron_model (Sonnet by default). Claude OAuth caps non-flagship models at high and rejects max. With a persistent cron session this also poisons every subsequent run on the same sdk_session_id.

The main interactive model (Opus) accepts max, so just lowering the global default would degrade the interactive experience to fix cron.

Fix

Add dedicated agent.cron_thinking and agent.cron_effort settings (default high) and a small _select_thinking_effort(agent_config, source) helper that returns the right pair for the session source:

• source in {"cron", "hook"} → cron_thinking / cron_effort
• everything else → thinking / effort (unchanged)

Defaults match what works under OAuth on Sonnet (high). Users with a provider that accepts max for Sonnet can lift the defaults.

Composes cleanly with the existing model-aware _parse_thinking_config(value, model) / _effective_effort(value, model) helpers — _select_thinking_effort only picks the source-appropriate input, the model-aware step still gates per-model legality.

Tests

tests/test_engine_options.py (new, 13 tests, all passing):

• _select_thinking_effort returns cron_* for cron and hook, defaults for everything else
• explicit override + None handling
• defaults of high for cron_thinking / cron_effort

Full suite: 1164 passed, 2 skipped (excluding pre-existing tests/test_cron.py::TestMaybeRotateContext rotate_at failures unrelated to this change — present on main too).

Files

• nerve/config.py — add cron_thinking / cron_effort to AgentConfig with "high" defaults
• nerve/agent/engine.py — _select_thinking_effort helper, used at session-start path
• nerve/bootstrap.py — surface in bootstrap defaults
• config.example.yaml, docs/config.md — document the two new keys
• tests/test_engine_options.py — new

History

Previously opened as #53, closed in error against the wrong target. This is the recreated version against upstream, rebased onto current main with the model-aware _parse_thinking_config / _effective_effort API.

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