diff --git a/README.md b/README.md
index c6ee0be..f858df2 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,7 @@ Let an Agent interact with your computer over HTTP, with grid-aware screenshots
 - **Window lifecycle endpoints**: list/focus/restore/minimize/maximize/close windows via `GET /windows` + `POST /windows/action`
 - **Structured launch endpoint**: start an app/process without dropping to a shell via `POST /launch`
 - **Wait/sync endpoint**: poll for text, window, or visual state changes via `POST /wait`
+- **Vision helper endpoints**: compare screenshots and measure stability via `POST /vision/diff` and `POST /vision/stability`
 - **OCR endpoints**: extract text blocks or search for matching text via `POST /ocr` and `POST /ocr/find`
 - **Command execution endpoint**: run PowerShell/Bash/CMD commands via `POST /exec`
 - **Coordinate transform metadata** in visual responses so agents can map grid cells to real pixels
diff --git a/docs/API.md b/docs/API.md
index 72c8f3a..27c2b66 100644
--- a/docs/API.md
+++ b/docs/API.md
@@ -282,6 +282,70 @@ Notes:
 - If `wait_for_window=true`, the server polls for a matching window and returns `window_found`.
 - `dry_run=true` returns the resolved argv/cwd without launching.
 
+## `POST /vision/diff`
+
+Measure whether a screen region changed meaningfully between two captures.
+
+Query params:
+
+- `screen` (int, default `0`) - used for `mode=screen` and `mode=region`
+
+Compare live captures:
+
+```json
+{
+  "mode": "region",
+  "region_x": 120,
+  "region_y": 80,
+  "region_width": 600,
+  "region_height": 300,
+  "delay_ms": 400,
+  "diff_threshold": 0.01
+}
+```
+
+Compare provided images:
+
+```json
+{
+  "mode": "image",
+  "before_image_base64": "iVBORw0KGgoAAA...",
+  "after_image_base64": "iVBORw0KGgoBBB...",
+  "diff_threshold": 0.01
+}
+```
+
+Response includes:
+- `diff_ratio` — average normalized pixel difference
+- `changed` — whether `diff_ratio >= diff_threshold`
+- `region` — compared region
+
+## `POST /vision/stability`
+
+Measure whether a screen region stays visually stable over a short interval.
+
+Query params:
+
+- `screen` (int, default `0`)
+
+```json
+{
+  "region_x": 0,
+  "region_y": 0,
+  "region_width": 1920,
+  "region_height": 1080,
+  "sample_interval_ms": 250,
+  "duration_ms": 1200,
+  "diff_threshold": 0.005
+}
+```
+
+Response includes:
+- `stable`
+- `sample_count`
+- `max_diff_ratio`
+- `avg_diff_ratio`
+
 ## `POST /wait`
 
 Wait on a structured UI condition instead of guessing sleep durations.
diff --git a/server/app.py b/server/app.py
index 8822492..30d8564 100644
--- a/server/app.py
+++ b/server/app.py
@@ -246,6 +246,38 @@ class OCRFindRequest(OCRRequest):
     max_results: int = Field(default=20, ge=1, le=200)
 
 
+class VisionDiffRequest(BaseModel):
+    mode: Literal["screen", "region", "image"] = "screen"
+    region_x: int | None = Field(default=None, ge=0)
+    region_y: int | None = Field(default=None, ge=0)
+    region_width: int | None = Field(default=None, gt=0)
+    region_height: int | None = Field(default=None, gt=0)
+    before_image_base64: str | None = None
+    after_image_base64: str | None = None
+    delay_ms: int = Field(default=300, ge=0, le=60000)
+    diff_threshold: float = Field(default=0.01, ge=0.0, le=1.0)
+
+    @model_validator(mode="after")
+    def _validate_inputs(self):
+        if self.mode == "region":
+            required = [self.region_x, self.region_y, self.region_width, self.region_height]
+            if any(v is None for v in required):
+                raise ValueError("region_x, region_y, region_width, region_height are required for mode=region")
+        if self.mode == "image" and (not self.before_image_base64 or not self.after_image_base64):
+            raise ValueError("before_image_base64 and after_image_base64 are required for mode=image")
+        return self
+
+
+class VisionStabilityRequest(BaseModel):
+    region_x: int | None = Field(default=None, ge=0)
+    region_y: int | None = Field(default=None, ge=0)
+    region_width: int | None = Field(default=None, gt=0)
+    region_height: int | None = Field(default=None, gt=0)
+    sample_interval_ms: int = Field(default=250, ge=50, le=10000)
+    duration_ms: int = Field(default=1200, ge=0, le=120000)
+    diff_threshold: float = Field(default=0.01, ge=0.0, le=1.0)
+
+
 
 def _auth(x_clickthrough_token: Optional[str] = Header(default=None)):
     token = SETTINGS["token"]
@@ -898,6 +930,91 @@ def _find_text_matches(blocks: list[dict], query: str, match_mode: str, group_li
     return matches[:max_results]
 
 
+def _compute_visual_diff(req: VisionDiffRequest, screen: int = 0) -> dict:
+    if req.mode == "image":
+        before = _decode_image_base64(req.before_image_base64 or "")
+        after = _decode_image_base64(req.after_image_base64 or "")
+        if before.size != after.size:
+            raise HTTPException(status_code=400, detail="before and after images must have matching dimensions")
+        diff_ratio = _image_diff_ratio(before, after)
+        return {
+            "mode": req.mode,
+            "region": {"x": 0, "y": 0, "width": before.size[0], "height": before.size[1]},
+            "diff_ratio": diff_ratio,
+            "changed": diff_ratio >= req.diff_threshold,
+            "diff_threshold": req.diff_threshold,
+        }
+
+    before, region, mon, displays, screen_selection = _capture_region_image(
+        screen,
+        req.region_x,
+        req.region_y,
+        req.region_width,
+        req.region_height,
+    )
+    if req.delay_ms > 0:
+        time.sleep(req.delay_ms / 1000.0)
+    after, _, _, _, _ = _capture_region_image(
+        screen,
+        region["x"],
+        region["y"],
+        region["width"],
+        region["height"],
+    )
+    diff_ratio = _image_diff_ratio(before, after)
+    return {
+        "mode": req.mode,
+        "region": region,
+        "diff_ratio": diff_ratio,
+        "changed": diff_ratio >= req.diff_threshold,
+        "diff_threshold": req.diff_threshold,
+        "screen": screen_selection,
+        "display": mon,
+        "delay_ms": req.delay_ms,
+    }
+
+
+def _measure_stability(req: VisionStabilityRequest, screen: int = 0) -> dict:
+    baseline, region, mon, displays, screen_selection = _capture_region_image(
+        screen,
+        req.region_x,
+        req.region_y,
+        req.region_width,
+        req.region_height,
+    )
+    sample_count = 0
+    max_diff_ratio = 0.0
+    diffs = []
+    deadline = time.time() + (req.duration_ms / 1000.0)
+    while time.time() < deadline:
+        time.sleep(req.sample_interval_ms / 1000.0)
+        current, _, _, _, _ = _capture_region_image(
+            screen,
+            region["x"],
+            region["y"],
+            region["width"],
+            region["height"],
+        )
+        diff_ratio = _image_diff_ratio(baseline, current)
+        diffs.append(diff_ratio)
+        max_diff_ratio = max(max_diff_ratio, diff_ratio)
+        sample_count += 1
+        baseline = current
+
+    return {
+        "stable": max_diff_ratio <= req.diff_threshold,
+        "region": region,
+        "sample_count": sample_count,
+        "max_diff_ratio": max_diff_ratio,
+        "avg_diff_ratio": round(sum(diffs) / len(diffs), 6) if diffs else 0.0,
+        "diff_threshold": req.diff_threshold,
+        "duration_ms": req.duration_ms,
+        "sample_interval_ms": req.sample_interval_ms,
+        "screen": screen_selection,
+        "display": mon,
+    }
+
+
 def _wait_for_condition(req: WaitRequest, screen: int = 0) -> dict:
     condition = req.condition
     deadline = time.time() + (req.timeout_ms / 1000.0)
@@ -1433,6 +1550,28 @@ def wait(req: WaitRequest, screen: int = 0, _: None = Depends(_auth)):
     }
 
 
+@app.post("/vision/diff")
+def vision_diff(req: VisionDiffRequest, screen: int = 0, _: None = Depends(_auth)):
+    result = _compute_visual_diff(req, screen)
+    return {
+        "ok": True,
+        "request_id": _request_id(),
+        "time_ms": _now_ms(),
+        "result": result,
+    }
+
+
+@app.post("/vision/stability")
+def vision_stability(req: VisionStabilityRequest, screen: int = 0, _: None = Depends(_auth)):
+    result = _measure_stability(req, screen)
+    return {
+        "ok": True,
+        "request_id": _request_id(),
+        "time_ms": _now_ms(),
+        "result": result,
+    }
+
+
 @app.post("/ocr")
 def ocr(req: OCRRequest, screen: int = 0, _: None = Depends(_auth)):
     image, region, mon, displays, screen_selection, source = _capture_ocr_source(req, screen)
diff --git a/skill/SKILL.md b/skill/SKILL.md
index c46a66b..53455a3 100644
--- a/skill/SKILL.md
+++ b/skill/SKILL.md
@@ -54,6 +54,8 @@ Say what you actually have: screenshots, OCR output, and fresh verification capt
 - `POST /windows/action` → focus/restore/minimize/maximize/close a matched window
 - `POST /launch` → start an app/process without dropping to a shell
 - `POST /wait?screen=0` → wait for text, window, or visual state changes
+- `POST /vision/diff?screen=0` → compare screenshots or regions for meaningful visual change
+- `POST /vision/stability?screen=0` → measure short-interval visual stability
 - `POST /ocr` → text extraction with bounding boxes from full screen, region, or provided image bytes
 - `POST /ocr/find?screen=0` → search OCR output for matching text candidates
 - `POST /action?screen=0` → single interaction (`move`, `click`, `scroll`, `type`, `hotkey`, ...)