diff --git a/README/WHATS_NEW_zh-CN.md b/README/WHATS_NEW_zh-CN.md
index 4e70958d..d895d39f 100644
--- a/README/WHATS_NEW_zh-CN.md
+++ b/README/WHATS_NEW_zh-CN.md
@@ -1,5 +1,11 @@
 # 本次更新 — AutoControl
 
+## 本次更新 (2026-06-23) — 感知式(YIQ)图像比对含反锯齿抑制
+
+会忽略反锯齿边缘的视觉回归比对。完整参考:[`docs/source/Zh/doc/new_features/v149_features_doc.rst`](../docs/source/Zh/doc/new_features/v149_features_doc.rst)。
+
+- **`perceptual_diff` / `assert_perceptual`**(`AC_perceptual_diff`):`image_difference` 计算原始逐通道差、`ssim_compare` 是整体分数——两者都未使用感知式度量也不忽略反锯齿(视觉比对误报的首要来源)。本功能在 YIQ 空间比较(pixelmatch 的色彩度量),并预设以形态学开运算移除单像素反锯齿细边差异,只计算实心变化(`include_aa=True` 保留)。返回 `{diff_pixels, diff_ratio, regions}`;`assert_perceptual` / `max_diff_ratio` 把关回归测试。可注入图像配对 → 无头可测(1px 细边 → 0、实心区块 → 计入)。
+
 ## 本次更新 (2026-06-23) — 软性断言(汇整所有失败)
 
 验证很多项,一次报告每一个失败。完整参考:[`docs/source/Zh/doc/new_features/v148_features_doc.rst`](../docs/source/Zh/doc/new_features/v148_features_doc.rst)。
diff --git a/README/WHATS_NEW_zh-TW.md b/README/WHATS_NEW_zh-TW.md
index b23336e5..851c7e13 100644
--- a/README/WHATS_NEW_zh-TW.md
+++ b/README/WHATS_NEW_zh-TW.md
@@ -1,5 +1,11 @@
 # 本次更新 — AutoControl
 
+## 本次更新 (2026-06-23) — 感知式(YIQ)影像比對含反鋸齒抑制
+
+會忽略反鋸齒邊緣的視覺回歸比對。完整參考:[`docs/source/Zh/doc/new_features/v149_features_doc.rst`](../docs/source/Zh/doc/new_features/v149_features_doc.rst)。
+
+- **`perceptual_diff` / `assert_perceptual`**(`AC_perceptual_diff`):`image_difference` 計算原始逐通道差、`ssim_compare` 是整體分數——兩者都未使用感知式度量也不忽略反鋸齒(視覺比對誤報的首要來源)。本功能在 YIQ 空間比較(pixelmatch 的色彩度量),並預設以形態學開運算移除單像素反鋸齒細邊差異,只計算實心變化(`include_aa=True` 保留)。回傳 `{diff_pixels, diff_ratio, regions}`;`assert_perceptual` / `max_diff_ratio` 把關回歸測試。可注入影像配對 → 無頭可測(1px 細邊 → 0、實心區塊 → 計入)。
+
 ## 本次更新 (2026-06-23) — 軟性斷言(彙整所有失敗)
 
 驗證很多項,一次回報每一個失敗。完整參考:[`docs/source/Zh/doc/new_features/v148_features_doc.rst`](../docs/source/Zh/doc/new_features/v148_features_doc.rst)。
diff --git a/WHATS_NEW.md b/WHATS_NEW.md
index 6e664e2d..07848db3 100644
--- a/WHATS_NEW.md
+++ b/WHATS_NEW.md
@@ -1,5 +1,11 @@
 # What's New — AutoControl
 
+## What's new (2026-06-23) — Perceptual (YIQ) Image Diff with Anti-Alias Suppression
+
+Visual-regression diffing that ignores anti-aliased edges. Full reference: [`docs/source/Eng/doc/new_features/v149_features_doc.rst`](docs/source/Eng/doc/new_features/v149_features_doc.rst).
+
+- **`perceptual_diff` / `assert_perceptual`** (`AC_perceptual_diff`): `image_difference` counts raw per-channel deltas and `ssim_compare` is a global score — neither uses a perceptual metric or ignores anti-aliasing, the #1 source of false-positive visual-diff failures. This compares in YIQ space (pixelmatch's colour metric) and, by default, removes thin 1px anti-aliased edge diffs via a morphological open so only solid changes count (`include_aa=True` keeps them). Returns `{diff_pixels, diff_ratio, regions}`; `assert_perceptual` / `max_diff_ratio` gate a regression test. Injectable image pair → headless-testable (a 1px fringe → 0, a solid block → counted).
+
 ## What's new (2026-06-23) — Soft Assertions (Aggregate Failures)
 
 Verify many things, report every failure at once. Full reference: [`docs/source/Eng/doc/new_features/v148_features_doc.rst`](docs/source/Eng/doc/new_features/v148_features_doc.rst).
diff --git a/docs/source/Eng/doc/new_features/v149_features_doc.rst b/docs/source/Eng/doc/new_features/v149_features_doc.rst
new file mode 100644
index 00000000..2ed717df
--- /dev/null
+++ b/docs/source/Eng/doc/new_features/v149_features_doc.rst
@@ -0,0 +1,42 @@
+Perceptual (YIQ) Image Diff with Anti-Alias Suppression
+=======================================================
+
+``visual_regression.image_difference`` counts raw per-channel max-delta pixels and
+``ssim_compare`` gives a global structural score. Neither uses a *perceptual* colour
+metric, and neither ignores **anti-aliased edges** — the #1 source of false-positive
+visual-diff failures across DPI and font-hinting. ``perceptual_diff`` compares pixels
+in YIQ space (the pixelmatch colour metric, far closer to human perception than RGB)
+and, by default, removes the thin one-pixel edge differences that anti-aliasing
+produces (a morphological open), so only *solid* changed regions count.
+
+Runs on an injectable image pair (ndarray / path / PIL), so it is headless-testable on
+synthetic arrays. OpenCV + NumPy come in via ``je_open_cv``; reuses the shared
+connected-component helper and RGB loader. Imports no ``PySide6``.
+
+Headless API
+------------
+
+.. code-block:: python
+
+    from je_auto_control import perceptual_diff, assert_perceptual
+
+    result = perceptual_diff("actual.png", "golden.png", threshold=0.1)
+    print(result.diff_pixels, result.diff_ratio, result.regions)
+
+    # Gate a visual-regression test (raises if the ratio is exceeded).
+    assert_perceptual("actual.png", "golden.png", max_diff_ratio=0.01)
+
+``perceptual_diff`` returns a ``PerceptualDiffResult`` (``diff_pixels``,
+``total_pixels``, ``diff_ratio``, and the ``regions`` boxes of the changed clusters).
+``threshold`` (0..1) is the pixelmatch sensitivity. ``include_aa=True`` keeps the thin
+edge differences instead of suppressing them. ``assert_perceptual`` raises
+``AutoControlActionException`` when ``diff_ratio`` exceeds ``max_diff_ratio``. Images of
+different sizes raise ``ValueError``.
+
+Executor command
+----------------
+
+``AC_perceptual_diff`` (``actual`` / ``expected`` / ``threshold`` / ``include_aa`` /
+``max_diff_ratio`` → ``{diff_pixels, total_pixels, diff_ratio, regions}``; raises when
+``max_diff_ratio`` is given and exceeded). It is exposed as the MCP tool
+``ac_perceptual_diff`` and as a Script Builder command under **Image**.
diff --git a/docs/source/Eng/eng_index.rst b/docs/source/Eng/eng_index.rst
index cec95c77..9f04af6d 100644
--- a/docs/source/Eng/eng_index.rst
+++ b/docs/source/Eng/eng_index.rst
@@ -171,6 +171,7 @@ Comprehensive guides for all AutoControl features.
    doc/new_features/v146_features_doc
    doc/new_features/v147_features_doc
    doc/new_features/v148_features_doc
+   doc/new_features/v149_features_doc
    doc/ocr_backends/ocr_backends_doc
    doc/observability/observability_doc
    doc/operations_layer/operations_layer_doc
diff --git a/docs/source/Zh/doc/new_features/v149_features_doc.rst b/docs/source/Zh/doc/new_features/v149_features_doc.rst
new file mode 100644
index 00000000..689e716f
--- /dev/null
+++ b/docs/source/Zh/doc/new_features/v149_features_doc.rst
@@ -0,0 +1,35 @@
+感知式(YIQ)影像比對含反鋸齒抑制
+====================================
+
+``visual_regression.image_difference`` 計算原始逐通道最大差像素數,``ssim_compare`` 給出整體結構分數。兩者都未使用
+*感知式*色彩度量,也都不忽略**反鋸齒邊緣**——那是跨 DPI 與字體微調時視覺比對誤報的首要來源。``perceptual_diff``
+在 YIQ 空間比較像素(pixelmatch 的色彩度量,比 RGB 更接近人眼感知),並預設移除反鋸齒造成的單像素細邊差異
+(形態學開運算),因此只計算*實心*變化區域。
+
+在可注入的影像配對(ndarray / 路徑 / PIL)上執行,因此可對合成陣列做無頭測試。OpenCV + NumPy 透過 ``je_open_cv``
+引入;沿用共用的連通元件輔助與 RGB 載入器。不匯入 ``PySide6``。
+
+無頭 API
+--------
+
+.. code-block:: python
+
+    from je_auto_control import perceptual_diff, assert_perceptual
+
+    result = perceptual_diff("actual.png", "golden.png", threshold=0.1)
+    print(result.diff_pixels, result.diff_ratio, result.regions)
+
+    # 把關視覺回歸測試(超出比例則拋例外)。
+    assert_perceptual("actual.png", "golden.png", max_diff_ratio=0.01)
+
+``perceptual_diff`` 回傳 ``PerceptualDiffResult``(``diff_pixels``、``total_pixels``、``diff_ratio``,以及變化叢集
+的 ``regions`` 方框)。``threshold``(0..1)是 pixelmatch 靈敏度。``include_aa=True`` 會保留細邊差異而不抑制。
+``assert_perceptual`` 在 ``diff_ratio`` 超過 ``max_diff_ratio`` 時丟出 ``AutoControlActionException``。不同尺寸的
+影像會丟出 ``ValueError``。
+
+執行器命令
+----------
+
+``AC_perceptual_diff``(``actual`` / ``expected`` / ``threshold`` / ``include_aa`` / ``max_diff_ratio`` →
+``{diff_pixels, total_pixels, diff_ratio, regions}``;給定 ``max_diff_ratio`` 且超出時拋例外)。它以 MCP 工具
+``ac_perceptual_diff`` 以及 Script Builder 中 **Image** 分類下的命令提供。
diff --git a/docs/source/Zh/zh_index.rst b/docs/source/Zh/zh_index.rst
index ea787926..90a9311e 100644
--- a/docs/source/Zh/zh_index.rst
+++ b/docs/source/Zh/zh_index.rst
@@ -171,6 +171,7 @@ AutoControl 所有功能的完整使用指南。
    doc/new_features/v146_features_doc
    doc/new_features/v147_features_doc
    doc/new_features/v148_features_doc
+   doc/new_features/v149_features_doc
    doc/ocr_backends/ocr_backends_doc
    doc/observability/observability_doc
    doc/operations_layer/operations_layer_doc
diff --git a/je_auto_control/__init__.py b/je_auto_control/__init__.py
index 7c23de29..dbffe17b 100644
--- a/je_auto_control/__init__.py
+++ b/je_auto_control/__init__.py
@@ -353,6 +353,10 @@
 )
 # Soft assertions (accumulate checks, raise the aggregate at block end)
 from je_auto_control.utils.soft_assert import SoftAssertions
+# Perceptual (YIQ) image diff with anti-alias edge suppression
+from je_auto_control.utils.perceptual_diff import (
+    PerceptualDiffResult, assert_perceptual, perceptual_diff,
+)
 # CI workflow annotations (GitHub Actions)
 from je_auto_control.utils.ci_annotations import (
     emit_annotations, format_annotation,
@@ -1220,6 +1224,9 @@ def start_autocontrol_gui(*args, **kwargs):
     "bring_to_front",
     "send_to_back",
     "SoftAssertions",
+    "perceptual_diff",
+    "assert_perceptual",
+    "PerceptualDiffResult",
     "emit_annotations", "format_annotation",
     "ClipboardHistory", "default_clipboard_history",
     "analyze_heal_log", "heal_stats", "scan_secrets",
diff --git a/je_auto_control/gui/script_builder/command_schema.py b/je_auto_control/gui/script_builder/command_schema.py
index 2821e82c..4328e3b3 100644
--- a/je_auto_control/gui/script_builder/command_schema.py
+++ b/je_auto_control/gui/script_builder/command_schema.py
@@ -553,6 +553,19 @@ def _add_image_specs(specs: List[CommandSpec]) -> None:
         ),
         description="Whether anything moved between two frames (+ activity score).",
     ))
+    specs.append(CommandSpec(
+        "AC_perceptual_diff", "Image", "Perceptual Diff (YIQ)",
+        fields=(
+            FieldSpec("actual", FieldType.FILE_PATH),
+            FieldSpec("expected", FieldType.FILE_PATH),
+            FieldSpec("threshold", FieldType.FLOAT, optional=True, default=0.1,
+                      min_value=0.0, max_value=1.0),
+            FieldSpec("include_aa", FieldType.BOOL, optional=True, default=False),
+            FieldSpec("max_diff_ratio", FieldType.FLOAT, optional=True,
+                      min_value=0.0, max_value=1.0),
+        ),
+        description="Perceptual image diff that ignores anti-aliased edges.",
+    ))
 
 
 def _add_ocr_specs(specs: List[CommandSpec]) -> None:
diff --git a/je_auto_control/utils/executor/action_executor.py b/je_auto_control/utils/executor/action_executor.py
index 2bf082da..366d2bd5 100644
--- a/je_auto_control/utils/executor/action_executor.py
+++ b/je_auto_control/utils/executor/action_executor.py
@@ -3784,6 +3784,20 @@ def _soft_assert(checks: Any, raise_on_fail: Any = False) -> Dict[str, Any]:
             "failures": soft.failures}
 
 
+def _perceptual_diff(actual: str, expected: str, threshold: Any = 0.1,
+                     include_aa: Any = False,
+                     max_diff_ratio: Any = None) -> Dict[str, Any]:
+    """Adapter: perceptual (YIQ) image diff with anti-alias suppression."""
+    from je_auto_control.utils.perceptual_diff import perceptual_diff
+    result = perceptual_diff(actual, expected, threshold=float(threshold),
+                             include_aa=bool(include_aa))
+    if max_diff_ratio is not None and result.diff_ratio > float(max_diff_ratio):
+        raise AutoControlActionException(
+            f"perceptual diff {result.diff_ratio} exceeds {max_diff_ratio}")
+    return {"diff_pixels": result.diff_pixels, "total_pixels": result.total_pixels,
+            "diff_ratio": result.diff_ratio, "regions": result.regions}
+
+
 def _with_modifiers(modifiers: Any, actions: Any) -> Dict[str, Any]:
     """Adapter: run nested actions while modifier keys are held down."""
     import json
@@ -5535,6 +5549,7 @@ def __init__(self):
             "AC_bring_to_front": _bring_to_front,
             "AC_send_to_back": _send_to_back,
             "AC_soft_assert": _soft_assert,
+            "AC_perceptual_diff": _perceptual_diff,
             "AC_tile_rect": _tile_rect,
             "AC_grid_rects": _grid_rects,
             "AC_cascade_rects": _cascade_rects,
diff --git a/je_auto_control/utils/mcp_server/tools/_factories.py b/je_auto_control/utils/mcp_server/tools/_factories.py
index 35b69ba5..dfe4b00d 100644
--- a/je_auto_control/utils/mcp_server/tools/_factories.py
+++ b/je_auto_control/utils/mcp_server/tools/_factories.py
@@ -3209,6 +3209,28 @@ def soft_assert_tools() -> List[MCPTool]:
     ]
 
 
+def perceptual_diff_tools() -> List[MCPTool]:
+    return [
+        MCPTool(
+            name="ac_perceptual_diff",
+            description=("Perceptual (YIQ) diff of 'actual' vs 'expected' image "
+                         "paths. By default suppresses anti-aliased edge diffs "
+                         "(include_aa=true to keep them). Returns {diff_pixels, "
+                         "total_pixels, diff_ratio, regions}; pass 'max_diff_ratio' "
+                         "to raise when exceeded. 'threshold' 0..1 sensitivity."),
+            input_schema=schema({
+                "actual": {"type": "string"},
+                "expected": {"type": "string"},
+                "threshold": {"type": "number"},
+                "include_aa": {"type": "boolean"},
+                "max_diff_ratio": {"type": "number"}},
+                required=["actual", "expected"]),
+            handler=h.perceptual_diff,
+            annotations=READ_ONLY,
+        ),
+    ]
+
+
 def ssim_tools() -> List[MCPTool]:
     return [
         MCPTool(
@@ -6716,7 +6738,7 @@ def media_assert_tools() -> List[MCPTool]:
     hsv_segment_tools, text_regions_tools, edge_lines_tools, expect_poll_tools,
     locator_chain_tools, rich_clipboard_tools, img_histogram_tools,
     motion_regions_tools, window_zorder_tools, soft_assert_tools,
-    plugin_sdk_tools, governance_tools,
+    perceptual_diff_tools, plugin_sdk_tools, governance_tools,
     credential_lease_tools, egress_tools, approval_testing_tools,
     trajectory_eval_tools, compliance_tools, agent_trace_tools,
     video_report_tools, fuzzy_tools, artifact_store_tools, image_dedup_tools,
diff --git a/je_auto_control/utils/mcp_server/tools/_handlers.py b/je_auto_control/utils/mcp_server/tools/_handlers.py
index fd16d66d..652b7f12 100644
--- a/je_auto_control/utils/mcp_server/tools/_handlers.py
+++ b/je_auto_control/utils/mcp_server/tools/_handlers.py
@@ -2288,6 +2288,12 @@ def soft_assert(checks, raise_on_fail=False):
     return _soft_assert(checks, raise_on_fail)
 
 
+def perceptual_diff(actual, expected, threshold=0.1, include_aa=False,
+                    max_diff_ratio=None):
+    from je_auto_control.utils.executor.action_executor import _perceptual_diff
+    return _perceptual_diff(actual, expected, threshold, include_aa, max_diff_ratio)
+
+
 def detect_drift(reference, current, threshold=0.25, bins=10):
     from je_auto_control.utils.executor.action_executor import _detect_drift
     return _detect_drift(reference, current, threshold, bins)
diff --git a/je_auto_control/utils/perceptual_diff/__init__.py b/je_auto_control/utils/perceptual_diff/__init__.py
new file mode 100644
index 00000000..2a6e7776
--- /dev/null
+++ b/je_auto_control/utils/perceptual_diff/__init__.py
@@ -0,0 +1,6 @@
+"""Perceptual (YIQ) image diff with anti-alias edge suppression."""
+from je_auto_control.utils.perceptual_diff.perceptual_diff import (
+    PerceptualDiffResult, assert_perceptual, perceptual_diff,
+)
+
+__all__ = ["PerceptualDiffResult", "assert_perceptual", "perceptual_diff"]
diff --git a/je_auto_control/utils/perceptual_diff/perceptual_diff.py b/je_auto_control/utils/perceptual_diff/perceptual_diff.py
new file mode 100644
index 00000000..3de32fb9
--- /dev/null
+++ b/je_auto_control/utils/perceptual_diff/perceptual_diff.py
@@ -0,0 +1,94 @@
+"""Perceptual (YIQ) image diff with anti-alias edge suppression.
+
+``visual_regression.image_difference`` counts raw per-channel max-delta pixels and
+``ssim`` gives a global structural score. Neither uses a *perceptual* colour metric, and
+neither ignores **anti-aliased edges** — the #1 source of false-positive visual-diff
+failures across DPI / font-hinting. This compares pixels in YIQ space (the pixelmatch
+colour metric, far closer to human perception than RGB) and, by default, suppresses the
+thin one-pixel edge differences that anti-aliasing produces via a morphological open, so
+only *solid* changed regions count.
+
+Runs on an injectable image pair (ndarray / path / PIL), so it is headless-testable on
+synthetic arrays. OpenCV + NumPy come in via ``je_open_cv``; reuses the shared
+connected-component helper and the RGB loader. Imports no ``PySide6``.
+"""
+from dataclasses import dataclass
+from typing import Any, Dict, List
+
+# Reuse the RGB loader (single source of truth, no copy).
+from je_auto_control.utils.color_region.color_region import _to_rgb
+
+ImageSource = Any
+_MAX_YIQ_DELTA = 35215.0          # pixelmatch: max possible YIQ delta for 255 diff
+
+
+@dataclass(frozen=True)
+class PerceptualDiffResult:
+    """The outcome of a perceptual diff: changed-pixel count, ratio and regions."""
+
+    diff_pixels: int
+    total_pixels: int
+    diff_ratio: float
+    regions: List[Dict[str, Any]]
+
+
+def _yiq_delta(first, second):
+    """Return the per-pixel squared YIQ colour distance between two RGB float images."""
+    weights_y = (0.29889531, 0.58662247, 0.11448223)
+    weights_i = (0.59597799, -0.27417610, -0.32180189)
+    weights_q = (0.21147017, -0.52261711, 0.31114694)
+
+    def channel(image, weights):
+        return (image[..., 0] * weights[0] + image[..., 1] * weights[1]
+                + image[..., 2] * weights[2])
+
+    delta_y = channel(first, weights_y) - channel(second, weights_y)
+    delta_i = channel(first, weights_i) - channel(second, weights_i)
+    delta_q = channel(first, weights_q) - channel(second, weights_q)
+    return 0.5053 * delta_y ** 2 + 0.299 * delta_i ** 2 + 0.1957 * delta_q ** 2
+
+
+def perceptual_diff(actual: ImageSource, expected: ImageSource, *,
+                    threshold: float = 0.1, include_aa: bool = False,
+                    min_area: int = 1) -> PerceptualDiffResult:
+    """Compare two images perceptually; return the changed pixels, ratio and regions.
+
+    ``threshold`` (0..1) is the pixelmatch sensitivity — higher tolerates more colour
+    difference before a pixel counts as changed. When ``include_aa`` is False (default)
+    a morphological open removes thin anti-aliased edge differences so only solid
+    changes remain. Different-sized images raise ``ValueError``.
+    """
+    import cv2
+    import numpy as np
+    from je_auto_control.utils.cv2_utils.blobs import connected_boxes
+    first = _to_rgb(actual).astype(np.float64)
+    second = _to_rgb(expected).astype(np.float64)
+    if first.shape != second.shape:
+        raise ValueError(f"images must be the same size: {first.shape} vs "
+                         f"{second.shape}")
+    max_delta = _MAX_YIQ_DELTA * float(threshold) * float(threshold)
+    mask = (_yiq_delta(first, second) > max_delta).astype(np.uint8)
+    if not include_aa:
+        kernel = cv2.getStructuringElement(cv2.MORPH_RECT, (3, 3))
+        mask = cv2.morphologyEx(mask, cv2.MORPH_OPEN, kernel)
+    diff_pixels = int(np.count_nonzero(mask))
+    total = int(mask.size)
+    regions = connected_boxes(mask * 255, int(min_area))
+    return PerceptualDiffResult(diff_pixels, total,
+                                round(diff_pixels / total, 6) if total else 0.0,
+                                regions)
+
+
+def assert_perceptual(actual: ImageSource, expected: ImageSource, *,
+                      threshold: float = 0.1, include_aa: bool = False,
+                      max_diff_ratio: float = 0.0) -> PerceptualDiffResult:
+    """Like :func:`perceptual_diff` but raise when the diff ratio exceeds ``max_diff_ratio``."""
+    from je_auto_control.utils.exception.exceptions import (
+        AutoControlActionException)
+    result = perceptual_diff(actual, expected, threshold=threshold,
+                             include_aa=include_aa)
+    if result.diff_ratio > float(max_diff_ratio):
+        raise AutoControlActionException(
+            f"perceptual diff {result.diff_ratio} exceeds {max_diff_ratio} "
+            f"({result.diff_pixels} pixels changed)")
+    return result
diff --git a/test/unit_test/headless/test_perceptual_diff_batch.py b/test/unit_test/headless/test_perceptual_diff_batch.py
new file mode 100644
index 00000000..7cbe513b
--- /dev/null
+++ b/test/unit_test/headless/test_perceptual_diff_batch.py
@@ -0,0 +1,75 @@
+"""Headless tests for perceptual (YIQ) image diff. No Qt."""
+import pytest
+
+import je_auto_control as ac
+from je_auto_control.utils.exception.exceptions import AutoControlActionException
+
+np = pytest.importorskip("numpy")
+pytest.importorskip("cv2")
+
+from je_auto_control.utils.perceptual_diff import (   # noqa: E402
+    PerceptualDiffResult, assert_perceptual, perceptual_diff,
+)
+
+
+def _base():
+    return np.full((100, 120, 3), 128, dtype=np.uint8)
+
+
+def _block():
+    img = _base()
+    img[30:60, 40:80] = (255, 0, 0)      # 40x30 solid change
+    return img
+
+
+def test_identical_has_no_diff():
+    result = perceptual_diff(_base(), _base().copy())
+    assert result.diff_pixels == 0 and result.diff_ratio == pytest.approx(0.0)
+
+
+def test_solid_block_is_counted():
+    result = perceptual_diff(_base(), _block())
+    assert isinstance(result, PerceptualDiffResult)
+    assert result.diff_pixels == 1200 and len(result.regions) == 1
+    assert result.diff_ratio == pytest.approx(0.1)
+
+
+def test_thin_fringe_suppressed_as_antialiasing():
+    fringe = _base()
+    fringe[:, 60:61] = (200, 200, 200)   # 1px-wide vertical edge difference
+    assert perceptual_diff(_base(), fringe, include_aa=False).diff_pixels == 0
+    assert perceptual_diff(_base(), fringe, include_aa=True).diff_pixels == 100
+
+
+def test_threshold_tolerates_small_colour_shift():
+    shifted = _base().copy()
+    shifted[:, :] = (132, 132, 132)      # small uniform shift
+    assert perceptual_diff(_base(), shifted, threshold=0.2).diff_pixels == 0
+
+
+def test_size_mismatch_raises():
+    with pytest.raises(ValueError):
+        perceptual_diff(_base(), np.zeros((10, 10, 3), dtype=np.uint8))
+
+
+def test_assert_perceptual_raises_over_budget():
+    with pytest.raises(AutoControlActionException):
+        assert_perceptual(_base(), _block(), max_diff_ratio=0.0)
+    assert assert_perceptual(_base(), _base().copy()).diff_pixels == 0
+
+
+# --- wiring ---------------------------------------------------------------
+
+def test_wiring():
+    assert "AC_perceptual_diff" in set(ac.executor.known_commands())
+    from je_auto_control.utils.mcp_server.tools import build_default_tool_registry
+    names = {t.name for t in build_default_tool_registry()}
+    assert "ac_perceptual_diff" in names
+    from je_auto_control.gui.script_builder.command_schema import _build_specs
+    specs = {s.command for s in _build_specs()}
+    assert "AC_perceptual_diff" in specs
+
+
+def test_facade_exports():
+    for attr in ("perceptual_diff", "assert_perceptual", "PerceptualDiffResult"):
+        assert hasattr(ac, attr) and attr in ac.__all__