diff --git a/.claude-plugin/plugin.json b/.claude-plugin/plugin.json
index 51295d2..7b8b058 100644
--- a/.claude-plugin/plugin.json
+++ b/.claude-plugin/plugin.json
@@ -14,5 +14,5 @@
   "license": "BSD-3-Clause",
   "name": "yas",
   "repository": "https://github.com/tmck-code/yet-another-statusline",
-  "version": "0.2.10"
+  "version": "0.2.11"
 }
diff --git a/claude/yas/config.py b/claude/yas/config.py
index 3ed8455..3f810b0 100644
--- a/claude/yas/config.py
+++ b/claude/yas/config.py
@@ -11,6 +11,7 @@
 
 from __future__ import annotations
 
+import json
 import os
 try:
     import tomllib
@@ -54,14 +55,16 @@ def _parse_pos_float(raw: object, origin: str) -> float:
         raise ValueError('must be > 0')
     return x
 
+BOOL_ALLOWLIST = ('1', '0', 'true', 'false')
 
 def _parse_bool(raw: object, origin: str) -> bool:
     if isinstance(raw, bool):
         return raw
-    # Env form: any non-empty value is true (empty strings are filtered out
-    # before reaching here). A non-bool from yas.toml is a type error.
     if origin == 'cli' or origin.startswith('env'):
-        return True
+        v = str(raw).strip().lower()
+        if v not in BOOL_ALLOWLIST:
+            raise ValueError(f"expected one of {', '.join(BOOL_ALLOWLIST)}")
+        return bool(json.loads(v))
     raise ValueError('expected a boolean')
 
 
diff --git a/pyproject.toml b/pyproject.toml
index 490a74f..12fb18c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "yet-another-statusline"
-version = "0.2.10"
+version = "0.2.11"
 description = "Claude Code statusline showing info at a glance: tokens, context, model, subagents, burn rate, skills, plugins, OpenSpec specs, task lists, and more"
 readme = "README.md"
 
diff --git a/test/test_config.py b/test/test_config.py
index 35af55c..900ac68 100644
--- a/test/test_config.py
+++ b/test/test_config.py
@@ -154,9 +154,36 @@ def test_toml_full_width_true(tmp_path: Path) -> None:
     assert cfg.full_width is True
 
 
-def test_env_full_width_any_nonempty_is_true(tmp_path: Path) -> None:
+def test_env_full_width_truthy_values(tmp_path: Path) -> None:
+    for val in ('1', 'true', 'True', 'TRUE'):
+        cfg = config.Config.load(env={'YAS_FULL_WIDTH': val}, config_dir=tmp_path)
+        assert cfg.full_width is True, f'expected True for YAS_FULL_WIDTH={val!r}'
+
+
+def test_env_full_width_falsy_values(tmp_path: Path) -> None:
+    for val in ('0', 'false', 'False', 'FALSE'):
+        cfg = config.Config.load(env={'YAS_FULL_WIDTH': val}, config_dir=tmp_path)
+        assert cfg.full_width is False, f'expected False for YAS_FULL_WIDTH={val!r}'
+
+
+def test_env_full_width_invalid_falls_through_to_default(tmp_path: Path) -> None:
+    cfg = config.Config.load(env={'YAS_FULL_WIDTH': 'yes'}, config_dir=tmp_path)
+    assert cfg.full_width is False  # invalid env value → default
+
+
+@requires_tomllib
+def test_env_full_width_zero_overrides_toml_true(tmp_path: Path) -> None:
+    (tmp_path / 'yas.toml').write_text('[layout]\nfull_width = true\n')
     cfg = config.Config.load(env={'YAS_FULL_WIDTH': '0'}, config_dir=tmp_path)
-    assert cfg.full_width is True
+    assert cfg.full_width is False
+
+
+@requires_tomllib
+def test_env_max_width_respected_when_full_width_disabled(tmp_path: Path) -> None:
+    (tmp_path / 'yas.toml').write_text('[layout]\nfull_width = true\n')
+    cfg = config.Config.load(env={'YAS_FULL_WIDTH': '0', 'YAS_MAX_WIDTH': '40'}, config_dir=tmp_path)
+    assert cfg.full_width is False
+    assert cfg.max_width == 40
 
 
 # 4.4 Broken TOML + unknown keys
diff --git a/uv.lock b/uv.lock
index 02e4d36..df335e9 100644
--- a/uv.lock
+++ b/uv.lock
@@ -399,7 +399,7 @@ wheels = [
 
 [[package]]
 name = "yet-another-statusline"
-version = "0.2.10"
+version = "0.2.11"
 source = { virtual = "." }
 
 [package.dev-dependencies]