test: settings output_language survives save→apply→recreate

Integration test driving the real bridge _save() and engine
_resolve_output_language(): a language chosen in the settings UI is written to
both the persistent volume and the runtime config, applies immediately (config
wins over the OUTPUT_LANGUAGE env), and survives a simulated container recreate
(entrypoint re-renders the config then merges the persistent override). Also
asserts the persona and reply directive both follow the persisted language.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

tests/test_settings_output_language_persistence.py

@@ -0,0 +1,119 @@
+"""End-to-end persistence of the output_language settings change.
+
+Closes the loop the reviewer flagged: a language chosen in the settings web UI
+must (1) take effect immediately for the reply engine and (2) survive a
+container recreate. The pieces:
+
+  bridge._save()        -> writes BOTH /data/jarvis-settings.json (persistent)
+                           and JARVIS_CONFIG_PATH (live runtime config)
+  entrypoint merge      -> on recreate, re-renders config from the env template
+                           then merges the persistent overrides back on top
+  engine._resolve_output_language() -> reads JARVIS_CONFIG_PATH, config wins
+                           over the OUTPUT_LANGUAGE env
+
+This test drives the REAL bridge save function and the REAL engine resolver
+(the resolver is loaded standalone because the full engine import needs the
+mcp package, which isn't installed in CI here). It simulates the env default
+disagreeing with the chosen language, which is exactly the bug condition.
+"""
+
+import ast
+import json
+import os
+from pathlib import Path
+
+import pytest
+
+# bridge.settings_web imports only stdlib at module load (flask is imported
+# lazily inside register()), so it is safe to import directly.
+import sys
+
+sys.path.insert(0, str(Path(__file__).resolve().parents[1] / "bridge"))
+import settings_web  # noqa: E402
+
+
+def _load_resolver():
+    """Load engine._resolve_output_language + _extra_config without importing
+    the heavy jarvis package (which pulls in the optional mcp dependency)."""
+    src = (
+        Path(__file__).resolve().parents[1]
+        / "src/jarvis/reply/engine.py"
+    ).read_text("utf-8")
+    tree = ast.parse(src)
+    wanted = {"_extra_config", "_resolve_output_language"}
+    mod = ast.Module(
+        body=[
+            n
+            for n in tree.body
+            if isinstance(n, ast.FunctionDef) and n.name in wanted
+        ],
+        type_ignores=[],
+    )
+    ns = {"os": os, "Optional": __import__("typing").Optional}
+    exec(compile(mod, "engine_subset", "exec"), ns)  # noqa: S102
+    return ns["_resolve_output_language"]
+
+
+def _simulate_recreate_merge(template_lang: str, config_path: Path, persist_path: Path):
+    """Mirror docker/entrypoint.sh: re-render the runtime config from the env
+    template, then merge the persistent overrides on top."""
+    config_path.write_text(json.dumps({"output_language": template_lang}), "utf-8")
+    if persist_path.exists():
+        base = json.loads(config_path.read_text("utf-8"))
+        ov = json.loads(persist_path.read_text("utf-8"))
+        base.update(ov)
+        config_path.write_text(json.dumps(base, ensure_ascii=False, indent=2), "utf-8")
+
+
+@pytest.mark.integration
+def test_settings_save_applies_and_survives_recreate(monkeypatch, tmp_path):
+    config_path = tmp_path / "jarvis.json"
+    persist_path = tmp_path / "data" / "jarvis-settings.json"
+    # The compose env default is the "old" language that must be overridden.
+    monkeypatch.setenv("OUTPUT_LANGUAGE", "English")
+    monkeypatch.setenv("JARVIS_CONFIG_PATH", str(config_path))
+    monkeypatch.setenv("JARVIS_SETTINGS_PATH", str(persist_path))
+    # Start from the env-rendered config (as entrypoint would produce).
+    config_path.write_text(json.dumps({"output_language": "English"}), "utf-8")
+
+    resolve = _load_resolver()
+    # Before the change: the env default wins.
+    assert resolve() == "English"
+
+    # 1) User saves Korean in the settings UI.
+    settings_web._save({"output_language": "Korean"})
+
+    # Both targets are written.
+    assert json.loads(config_path.read_text("utf-8"))["output_language"] == "Korean"
+    assert json.loads(persist_path.read_text("utf-8"))["output_language"] == "Korean"
+
+    # 2) Applies immediately: the resolver now returns Korean (config > env).
+    assert resolve() == "Korean"
+
+    # 3) Survives a container recreate: entrypoint re-renders the config from the
+    #    env template (still English) then merges the persistent override.
+    _simulate_recreate_merge("English", config_path, persist_path)
+    assert json.loads(config_path.read_text("utf-8"))["output_language"] == "Korean"
+    assert resolve() == "Korean"
+
+
+@pytest.mark.integration
+def test_persona_and_directive_follow_persisted_language(monkeypatch, tmp_path):
+    """After persistence, the persona and the reply directive both lock to the
+    saved language, not the env default."""
+    from jarvis.system_prompt import build_system_prompt, reply_language_directive
+
+    config_path = tmp_path / "jarvis.json"
+    persist_path = tmp_path / "data" / "jarvis-settings.json"
+    monkeypatch.setenv("OUTPUT_LANGUAGE", "English")
+    monkeypatch.setenv("JARVIS_CONFIG_PATH", str(config_path))
+    monkeypatch.setenv("JARVIS_SETTINGS_PATH", str(persist_path))
+    config_path.write_text(json.dumps({"output_language": "English"}), "utf-8")
+
+    settings_web._save({"output_language": "Korean"})
+    lang = _load_resolver()()
+
+    persona = build_system_prompt("Jarvis", lang)
+    directive = reply_language_directive(lang, "melo")
+    assert "in Korean" in persona and "in English" not in persona
+    assert directive is not None and "Korean" in directive