fix(cli): honor env precedence for LLM and run config

Interactive selections and flag defaults overrode TRADINGAGENTS_* env vars.
Rule: an explicit env value or CLI flag wins; otherwise the env-applied
default is kept.

- Research depth: skip the prompt when both round-count env vars are set, and
  stop overwriting them (#977).
- Checkpoint: --checkpoint/--no-checkpoint is tri-state; omitting it keeps
  TRADINGAGENTS_CHECKPOINT_ENABLED (#976).
- Docker ollama: use TRADINGAGENTS_LLM_PROVIDER + OLLAMA_BASE_URL, not a bare
  LLM_PROVIDER the overlay never reads (#975).
- Reasoning/thinking knobs: settable via env; the prompt is skipped when set.
- Effort gating: forward effort only to models that accept it (Anthropic
  Opus 4.5+/Sonnet 4.6+, OpenAI reasoning models); drop it elsewhere.
- Boolean env values: raise a named error on invalid input instead of
  silently becoming False.

tests/test_cli_config_precedence.py

@@ -0,0 +1,69 @@
+"""CLI config precedence (#976, #977).
+
+An explicit environment override for the debate/risk round counts, or the
+checkpoint flag, must win over the interactive research-depth selection — the CLI
+must not clobber an env-configured value back to a prompt/flag default.
+"""
+
+from unittest import mock
+
+import pytest
+
+import cli.main as m
+
+# Minimal selections dict shaped like get_user_selections()'s return value.
+SELECTIONS = {
+    "research_depth": 5,
+    "shallow_thinker": "gpt-5.4-mini",
+    "deep_thinker": "gpt-5.5",
+    "backend_url": None,
+    "llm_provider": "openai",
+    "google_thinking_level": None,
+    "openai_reasoning_effort": None,
+    "anthropic_effort": None,
+    "output_language": "English",
+}
+
+
+def test_research_depth_sets_both_rounds_without_env(monkeypatch):
+    for var in ("TRADINGAGENTS_MAX_DEBATE_ROUNDS", "TRADINGAGENTS_MAX_RISK_ROUNDS"):
+        monkeypatch.delenv(var, raising=False)
+    cfg = m._build_run_config(SELECTIONS, checkpoint=None)
+    assert cfg["max_debate_rounds"] == 5
+    assert cfg["max_risk_discuss_rounds"] == 5
+
+
+def test_env_round_counts_win_over_selection(monkeypatch):
+    monkeypatch.setenv("TRADINGAGENTS_MAX_DEBATE_ROUNDS", "2")
+    monkeypatch.setenv("TRADINGAGENTS_MAX_RISK_ROUNDS", "4")
+    # DEFAULT_CONFIG already reflects the env (applied at import); emulate that.
+    patched = dict(m.DEFAULT_CONFIG, max_debate_rounds=2, max_risk_discuss_rounds=4)
+    with mock.patch.object(m, "DEFAULT_CONFIG", patched):
+        cfg = m._build_run_config(SELECTIONS, checkpoint=None)
+    assert cfg["max_debate_rounds"] == 2  # env value, not research_depth=5
+    assert cfg["max_risk_discuss_rounds"] == 4
+
+
+def test_partial_env_only_overrides_that_count(monkeypatch):
+    monkeypatch.setenv("TRADINGAGENTS_MAX_DEBATE_ROUNDS", "2")
+    monkeypatch.delenv("TRADINGAGENTS_MAX_RISK_ROUNDS", raising=False)
+    patched = dict(m.DEFAULT_CONFIG, max_debate_rounds=2)
+    with mock.patch.object(m, "DEFAULT_CONFIG", patched):
+        cfg = m._build_run_config(SELECTIONS, checkpoint=None)
+    assert cfg["max_debate_rounds"] == 2  # env wins
+    assert cfg["max_risk_discuss_rounds"] == 5  # falls through to research_depth
+
+
+def test_checkpoint_none_preserves_env_default():
+    patched = dict(m.DEFAULT_CONFIG, checkpoint_enabled=True)  # e.g. env-enabled
+    with mock.patch.object(m, "DEFAULT_CONFIG", patched):
+        cfg = m._build_run_config(SELECTIONS, checkpoint=None)
+    assert cfg["checkpoint_enabled"] is True  # not clobbered back to False
+
+
+@pytest.mark.parametrize("flag", [True, False])
+def test_checkpoint_flag_overrides_env(flag):
+    patched = dict(m.DEFAULT_CONFIG, checkpoint_enabled=not flag)
+    with mock.patch.object(m, "DEFAULT_CONFIG", patched):
+        cfg = m._build_run_config(SELECTIONS, checkpoint=flag)
+    assert cfg["checkpoint_enabled"] is flag