"""IMP-33 u1 — AI fallback Settings defaults (locked).

These defaults are the binding contract from Stage 2 plan (per-unit u1):
  - ai_fallback_enabled        = False        (master flag OFF; fallback path only)
  - ai_fallback_model          = "claude-opus-4-6-20250415"
  - ai_fallback_timeout_s      = 60.0
  - ai_fallback_max_retries    = 3
  - ai_fallback_backoff_base_s = 1.0
  - ai_fallback_backoff_cap_s  = 8.0
  - ai_fallback_backoff_jitter = 0.3
  - ai_fallback_budget_per_run = 10
  - ai_fallback_circuit_breaker_threshold = 5

Downstream u4 (client) MUST source timeout/retry/backoff/budget/circuit from
Settings; inline literals are forbidden by Stage 2 plan.
"""
from __future__ import annotations

from src.config import Settings


def test_ai_fallback_master_flag_default_off() -> None:
    s = Settings()
    assert s.ai_fallback_enabled is False, (
        "AI fallback master flag MUST default OFF (normal path AI=0 contract)."
    )


def test_ai_fallback_model_default_locked() -> None:
    s = Settings()
    assert s.ai_fallback_model == "claude-opus-4-6-20250415"


def test_ai_fallback_retry_timeout_backoff_defaults_locked() -> None:
    s = Settings()
    assert s.ai_fallback_timeout_s == 60.0
    assert s.ai_fallback_max_retries == 3
    assert s.ai_fallback_backoff_base_s == 1.0
    assert s.ai_fallback_backoff_cap_s == 8.0
    assert s.ai_fallback_backoff_jitter == 0.3


def test_ai_fallback_budget_and_circuit_defaults_locked() -> None:
    s = Settings()
    assert s.ai_fallback_budget_per_run == 10
    assert s.ai_fallback_circuit_breaker_threshold == 5