diff --git a/README.md b/README.md
index f4c3ffe..6f2a681 100644
--- a/README.md
+++ b/README.md
@@ -31,7 +31,9 @@ cargo run --release -- /path/to/screenshot.png
 
 ## Color grouping and mapping
 
-**Group similar colors** is enabled by default in the **Palette**. Nearby shades
+**Group similar colors** is enabled by default in the **Palette**. The default
+**Edited** view shows the resulting colors. Switch to **Source / map** to select
+original colors for replacement. Nearby shades
 from scaling or compression share a row showing their combined percentage and
 shade count. Adjust **Tolerance** (default 8, range 0–32) to control the maximum
 difference in each RGB channel from the group's most frequent color. Groups do
@@ -39,7 +41,8 @@ not chain together through intermediate shades. Turn grouping off or set toleran
 to zero for the exact palette. Hover a row to highlight its pixels in magenta in
 the crop preview; this temporary highlight is never exported.
 
-Freeze a capture or import an image, then click **Map** beside a palette row.
+Freeze a capture or import an image, choose **Source / map**, then click **Map**
+beside a palette row.
 In **Color mapping**, click its replacement swatch to choose another color or enter
 RGB values. Every original shade in that group maps to the chosen replacement.
 Add multiple mappings to try a new palette. Each mapping keeps its original group
@@ -54,13 +57,68 @@ changes, pause during live capture, and return when frozen again. Opening a new
 image or choosing a new capture source clears them.
 
 Mappings apply before the preview adjustments or vision filter. Source preview,
-analysis, copied pixel values, and **Save crop PNG** still use the original.
+copied pixel values, and **Save crop PNG** still use the original. Color analysis
+and the vision check use the edited selection.
 **Save mapped crop PNG** exports the crop with replacements, preserving alpha
 and excluding preview adjustments and filters.
 
+## Automatic harmony
+
+Freeze a capture or import an image, open **Harmonize**, and enable **Preview
+harmony**. Choose **Monochromatic**, **Analogous**, **Complementary**,
+**Split-Complementary**, or **Triadic**. The app fits that rule to the crop automatically, then moves its hue families toward the
+chosen harmony while preserving shading. **Strength** blends from the input
+at 0% to the full transformation at 100%. **Rotation**, or dragging the color
+wheel, changes the palette's direction. White dots on the wheel mark input hue
+families; colored spokes mark target hues. The wheel shows targets at full
+strength. **Auto fit** resets rotation and fits the current crop again.
+
+**Protect neutrals** is enabled by default: gray and near-gray colors stay
+unchanged, with a gradual transition into chromatic colors. **Reset harmony**
+turns harmony off and restores its defaults. Disabling **Preview harmony** lets
+you compare with the input (including any enabled manual mappings). Settings
+pause during live capture, resume when frozen, and reset for a new image or
+capture source. Changing the crop or manual mappings refits the harmony while
+retaining your rotation and strength.
+
+Harmony works in OKLCH: it holds perceptual lightness and chroma while shifting
+hue, reducing chroma when needed to fit sRGB. It retains small hue variations
+within a family and compresses broad families into bands around target hues.
+Monochromatic instead converges to a single hue at full strength, retaining
+lightness and chroma variations (with neutral protection still applied).
+The offsets are 0° for monochromatic, −30°/0°/+30° for analogous, 0°/180° for
+complementary, 0°/150°/210° for split-complementary, and 0°/120°/240° for triadic,
+on the **OKLCH** wheel. These angles do not produce
+identical color pairs to HSV or traditional artist color wheels.
+
+The fit uses a circular hue histogram, finds hue families, and searches for the
+orientation requiring the least weighted squared hue movement. Counts are
+square-root weighted after hue binning so a large background has less influence
+and compression-generated near-duplicates don't each get a separate vote. This
+is an experimental palette heuristic: it does not recognize objects, protect
+skin or gameplay indicators automatically, or guarantee that every target hue
+is used. Families may merge, and family boundaries can still affect subtle hue
+ramps. Start with moderate strength and compare the result in context.
+
+The processing order is **source → manual mappings → harmony → preview filter
+or adjustments**. The source preview and copied pixel values remain original; color analysis and
+the vision check use the edited selection. **Save harmonized crop PNG** includes enabled mappings and harmony,
+preserving transparency, without hover highlights, preview filters, or
+adjustments. **Save mapped crop PNG** still saves only manual replacements;
+**Save crop PNG** still saves the original.
+
+The conversion uses [Björn Ottosson's Oklab transforms](https://bottosson.github.io/posts/oklab/).
+
 ## Color analysis and vision checks
 
-The **Color analysis** tab has four distributions:
+The **Color analysis** tab uses the edited selection after active mappings,
+harmony, and the selected filter or adjustments. Histograms, means, neutral
+counts, distinct-color weighting, and the **Edited** palette all update together.
+Merged colors count once for distinct-color weighting. Diagnostic simulation
+previews and hover highlights are excluded, just as in the vision check.
+**Source / map** keeps the original palette available for choosing replacements.
+
+The tab has four distributions:
 
 - **Hue**: HSV hue in 36 ten-degree bins; saturation below 5% counts as neutral.
 - **Saturation**: HSV saturation, from neutral to fully saturated.
@@ -80,8 +138,8 @@ tritanopia, or grayscale directly to the crop preview, or select **Original**
 to use the live color adjustment sliders. The first three use the
 Machado–Oliveira–Fernandes full-severity model, applied in linear RGB and then
 encoded back to sRGB. Grayscale uses relative luminance and tests removal of color
-cues; it does not model all aspects of achromatopsia. Preview mode does not change
-histograms, copied pixel values, or the exported PNG: those always use the original.
+cues; it does not model all aspects of achromatopsia. The selected filter updates color analysis and the vision check. Copied pixel
+values and **Save crop PNG** still use the original.
 
 **Invert** replaces each RGB channel with its complement (255 minus the channel).
 With **Original** selected, adjust **Hue shift** (−180° to +180°), **Saturation**
@@ -94,12 +152,24 @@ while another filter is selected and applied again when returning to Original.
 Filters preserve alpha and always start from source pixels, so edits do not
 accumulate rounding errors.
 
-**Vision check** automatically checks all four scenarios. It flags pairs whose
-OKLab distance falls from at least 0.08 to at most 0.04, losing at least 50% of the
-original separation. These are project-specific screening heuristics, not
-validated visibility thresholds or WCAG criteria. Each scenario shows original
+**Vision check** automatically checks all four scenarios against the **edited
+selection**, after enabled group/manual mappings, harmony, and the selected
+filter or adjustments. It updates when these edits or the crop change. Palette
+grouping alone only organizes colors; mapping a group changes the checked pixels.
+Colors that merge through editing count as one color, and opaque-pixel coverage
+is recalculated from the result. Color distributions and the edited palette use
+those same pixels; **Source / map** remains available for mapping input colors.
+
+The report's **Preview** buttons add a separate simulation of those edited
+pixels. They do not change the selected filter or feed simulated pixels back into
+the report. Use **Return to edited preview** to remove this simulation. Temporary
+palette hover highlights are also excluded from the check.
+
+The check flags pairs whose OKLab distance falls from at least 0.08 to at most 0.04, losing at least 50% of the
+separation in the edited image. These are project-specific screening heuristics, not
+validated visibility thresholds or WCAG criteria. Each scenario shows edited
 and simulated swatches, numeric hex values, and up to six closest candidate pairs.
-The preview button opens the corresponding simulation for the current crop.
+The preview button opens the corresponding simulation for the edited crop.
 
 The check is bounded to the 64 most frequent **opaque** colors and reports both
 color and pixel coverage. Partially/fully transparent pixels have no known
@@ -156,6 +226,9 @@ repeated portal requests during/after capture. The portal regression test requir
 bus and does not open desktop dialogs. Color tests cover histogram endpoints and
 weighting, sRGB gamma, simulation reference colors, alpha handling, warning
 positives/negatives, palette coverage, and preserving source pixels.
+Harmony tests cover color-space reference values, gamut reduction, circular hue
+fitting, neutral protection, shading, alpha, preset rendering, crop and capture
+lifecycle, and exported PNG pixels.
 Actual portal capture requires a running
 Wayland desktop and permission through KDE's picker.
 
diff --git a/src/analysis/harmony.rs b/src/analysis/harmony.rs
new file mode 100644
index 0000000..d7eda07
--- /dev/null
+++ b/src/analysis/harmony.rs
@@ -0,0 +1,493 @@
+//! Hue-family harmonization in OKLCH. This is a palette heuristic, not object
+//! segmentation or an implementation of the Cohen-Or harmonization paper.
+use super::vision::{encode, linear_rgb, oklab};
+use std::collections::HashMap;
+
+const BINS: usize = 72;
+const BIN_WIDTH: f64 = 360.0 / BINS as f64;
+const NEUTRAL_CHROMA: f64 = 0.025;
+const BAND_WIDTH: f64 = 12.0;
+
+#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
+pub enum Scheme {
+    Monochromatic,
+    Analogous,
+    #[default]
+    Complementary,
+    SplitComplementary,
+    Triadic,
+}
+
+impl Scheme {
+    pub const ALL: [Self; 5] = [
+        Self::Monochromatic,
+        Self::Analogous,
+        Self::Complementary,
+        Self::SplitComplementary,
+        Self::Triadic,
+    ];
+
+    pub fn label(self) -> &'static str {
+        match self {
+            Self::Monochromatic => "Monochromatic",
+            Self::Analogous => "Analogous",
+            Self::Complementary => "Complementary",
+            Self::SplitComplementary => "Split-Complementary",
+            Self::Triadic => "Triadic",
+        }
+    }
+
+    pub fn description(self) -> &'static str {
+        match self {
+            Self::Monochromatic => "One hue, with variations in lightness and color intensity.",
+            Self::Analogous => "Nearby hue families for a more unified palette.",
+            Self::Complementary => "Two opposing hue regions for a main color and an accent.",
+            Self::SplitComplementary => "A main hue and two hues on either side of its opposite.",
+            Self::Triadic => "Three evenly spaced hue regions for a varied palette.",
+        }
+    }
+
+    pub fn offsets(self) -> &'static [f64] {
+        match self {
+            Self::Monochromatic => &[0.0],
+            Self::Analogous => &[-30.0, 0.0, 30.0],
+            Self::Complementary => &[0.0, 180.0],
+            Self::SplitComplementary => &[0.0, 150.0, 210.0],
+            Self::Triadic => &[0.0, 120.0, 240.0],
+        }
+    }
+}
+
+#[derive(Clone, Copy, Debug, PartialEq)]
+pub struct Harmony {
+    pub enabled: bool,
+    pub scheme: Scheme,
+    pub strength: f64,
+    pub rotation: f64,
+    pub protect_neutrals: bool,
+}
+
+impl Default for Harmony {
+    fn default() -> Self {
+        Self {
+            enabled: false,
+            scheme: Scheme::default(),
+            strength: 0.8,
+            rotation: 0.0,
+            protect_neutrals: true,
+        }
+    }
+}
+
+#[derive(Debug)]
+pub struct Family {
+    pub hue: f64,
+    weight: f64,
+    width: f64,
+    target: f64,
+}
+
+#[derive(Default, Debug)]
+pub struct Fit {
+    pub orientation: f64,
+    pub families: Vec<Family>,
+}
+
+/// Signed shortest arc, including wrapping between 359° and 0°.
+pub fn angle_delta(from: f64, to: f64) -> f64 {
+    (to - from + 180.0).rem_euclid(360.0) - 180.0
+}
+
+fn lch(rgb: [u8; 3]) -> [f64; 3] {
+    let [l, a, b] = oklab(linear_rgb(rgb));
+    [l, a.hypot(b), b.atan2(a).to_degrees().rem_euclid(360.0)]
+}
+
+// Public-domain inverse transform by Björn Ottosson:
+// https://bottosson.github.io/posts/oklab/
+fn to_linear([l, c, h]: [f64; 3]) -> [f64; 3] {
+    let a = c * h.to_radians().cos();
+    let b = c * h.to_radians().sin();
+    let ll = (l + 0.3963377774 * a + 0.2158037573 * b).powi(3);
+    let m = (l - 0.1055613458 * a - 0.0638541728 * b).powi(3);
+    let s = (l - 0.0894841775 * a - 1.2914855480 * b).powi(3);
+    [
+        4.0767416621 * ll - 3.3077115913 * m + 0.2309699292 * s,
+        -1.2684380046 * ll + 2.6097574011 * m - 0.3413193965 * s,
+        -0.0041960863 * ll - 0.7034186147 * m + 1.7076147010 * s,
+    ]
+}
+
+fn in_gamut(rgb: [f64; 3]) -> bool {
+    rgb.iter().all(|v| (-1e-7..=1.0 + 1e-7).contains(v))
+}
+
+/// Reduce chroma only when needed to keep lightness and hue in sRGB gamut.
+pub fn from_lch([l, c, h]: [f64; 3]) -> [u8; 3] {
+    let rgb = to_linear([l, c, h]);
+    if in_gamut(rgb) {
+        return rgb.map(encode);
+    }
+    let (mut low, mut high) = (0.0, c);
+    for _ in 0..20 {
+        let mid = (low + high) / 2.0;
+        if in_gamut(to_linear([l, mid, h])) {
+            low = mid;
+        } else {
+            high = mid;
+        }
+    }
+    to_linear([l, low, h]).map(encode)
+}
+
+impl Fit {
+    pub fn new(colors: impl IntoIterator<Item = ([u8; 3], u64)>, settings: Harmony) -> Self {
+        let mut counts = [0.0; BINS];
+        let mut chroma = [0.0; BINS];
+        for (rgb, count) in colors {
+            let [_, c, h] = lch(rgb);
+            if c < 1e-5 || (settings.protect_neutrals && c <= NEUTRAL_CHROMA) {
+                continue;
+            }
+            let bin = (h / BIN_WIDTH).floor() as usize % BINS;
+            counts[bin] += count as f64;
+            chroma[bin] += c * count as f64;
+        }
+        // Count compression happens after hue binning, so compression-generated
+        // RGB duplicates do not gain extra votes. Small accents still contribute.
+        let weights: [f64; BINS] = std::array::from_fn(|i| {
+            if counts[i] == 0.0 {
+                0.0
+            } else {
+                counts[i].sqrt() * chroma[i] / counts[i]
+            }
+        });
+        let smooth: [f64; BINS] = std::array::from_fn(|i| {
+            weights[(i + BINS - 1) % BINS] + 2.0 * weights[i] + weights[(i + 1) % BINS]
+        });
+        let mut peaks: Vec<_> = (0..BINS)
+            .filter(|&i| {
+                smooth[i] > 0.0
+                    && smooth[i] >= smooth[(i + BINS - 1) % BINS]
+                    && smooth[i] >= smooth[(i + 1) % BINS]
+            })
+            .collect();
+        peaks.sort_by(|&a, &b| smooth[b].total_cmp(&smooth[a]).then(a.cmp(&b)));
+        let mut centers: Vec<f64> = Vec::new();
+        for bin in peaks {
+            let hue = (bin as f64 + 0.5) * BIN_WIDTH;
+            if centers
+                .iter()
+                .all(|&old| angle_delta(old, hue).abs() >= 30.0)
+            {
+                centers.push(hue);
+            }
+        }
+        if centers.is_empty() {
+            return Self::default();
+        }
+        // Refine each peak to a circular mean of its hue neighborhood.
+        let mut sums = vec![[0.0; 3]; centers.len()];
+        for (i, &weight) in weights.iter().enumerate() {
+            if weight == 0.0 {
+                continue;
+            }
+            let hue = (i as f64 + 0.5) * BIN_WIDTH;
+            let index = nearest(&centers, hue);
+            sums[index][0] += weight * hue.to_radians().cos();
+            sums[index][1] += weight * hue.to_radians().sin();
+            sums[index][2] += weight;
+        }
+        let mut families: Vec<_> = sums
+            .into_iter()
+            .filter(|s| s[2] > 0.0)
+            .map(|[x, y, weight]| Family {
+                hue: y.atan2(x).to_degrees().rem_euclid(360.0),
+                weight,
+                width: BIN_WIDTH,
+                target: 0.0,
+            })
+            .collect();
+        families.sort_by(|a, b| a.hue.total_cmp(&b.hue));
+        let centers: Vec<_> = families.iter().map(|f| f.hue).collect();
+        for (i, &weight) in weights.iter().enumerate() {
+            if weight == 0.0 {
+                continue;
+            }
+            let hue = (i as f64 + 0.5) * BIN_WIDTH;
+            let family = &mut families[nearest(&centers, hue)];
+            family.width = family
+                .width
+                .max(angle_delta(family.hue, hue).abs() + BIN_WIDTH / 2.0);
+        }
+        let orientation = (0..360)
+            .min_by(|&a, &b| {
+                fit_cost(&families, settings.scheme, a as f64)
+                    .total_cmp(&fit_cost(&families, settings.scheme, b as f64))
+                    .then(a.cmp(&b))
+            })
+            .unwrap() as f64;
+        let targets: Vec<_> = settings
+            .scheme
+            .offsets()
+            .iter()
+            .map(|h| h + orientation)
+            .collect();
+        for family in &mut families {
+            family.target = targets[nearest(&targets, family.hue)].rem_euclid(360.0);
+        }
+        Self {
+            orientation,
+            families,
+        }
+    }
+
+    fn apply(&self, rgb: [u8; 3], settings: Harmony) -> [u8; 3] {
+        if !settings.enabled || settings.strength == 0.0 || self.families.is_empty() {
+            return rgb;
+        }
+        let [l, c, hue] = lch(rgb);
+        if c < 1e-5 || (settings.protect_neutrals && c <= NEUTRAL_CHROMA) {
+            return rgb;
+        }
+        let family = self
+            .families
+            .iter()
+            .min_by(|a, b| {
+                angle_delta(a.hue, hue)
+                    .abs()
+                    .total_cmp(&angle_delta(b.hue, hue).abs())
+            })
+            .unwrap();
+        let offset = angle_delta(family.hue, hue);
+        let scale = if settings.scheme == Scheme::Monochromatic {
+            0.0
+        } else {
+            (BAND_WIDTH / family.width).min(1.0)
+        };
+        let shift =
+            angle_delta(family.hue, family.target) + settings.rotation + offset * (scale - 1.0);
+        // Fade in above the protected neutral range to avoid a sudden tint edge.
+        let protection = if settings.protect_neutrals {
+            ((c - NEUTRAL_CHROMA) / NEUTRAL_CHROMA).clamp(0.0, 1.0)
+        } else {
+            1.0
+        };
+        let strength = settings.strength.clamp(0.0, 1.0) * protection;
+        if shift.abs() < 1e-8 {
+            return rgb;
+        }
+        from_lch([l, c, hue + shift * strength])
+    }
+
+    pub fn apply_rgba(&self, rgba: &[u8], settings: Harmony) -> Vec<u8> {
+        let mut output = rgba.to_vec();
+        if !settings.enabled || settings.strength == 0.0 || self.families.is_empty() {
+            return output;
+        }
+        let mut cache = HashMap::new();
+        for pixel in output.as_chunks_mut::<4>().0 {
+            if pixel[3] == 0 {
+                continue;
+            }
+            let rgb = [pixel[0], pixel[1], pixel[2]];
+            pixel[..3].copy_from_slice(
+                cache
+                    .entry(rgb)
+                    .or_insert_with(|| self.apply(rgb, settings)),
+            );
+        }
+        output
+    }
+}
+
+fn nearest(hues: &[f64], hue: f64) -> usize {
+    (0..hues.len())
+        .min_by(|&a, &b| {
+            angle_delta(hue, hues[a])
+                .abs()
+                .total_cmp(&angle_delta(hue, hues[b]).abs())
+                .then(a.cmp(&b))
+        })
+        .unwrap()
+}
+
+fn fit_cost(families: &[Family], scheme: Scheme, orientation: f64) -> f64 {
+    families
+        .iter()
+        .map(|family| {
+            let distance = scheme
+                .offsets()
+                .iter()
+                .map(|offset| angle_delta(family.hue, orientation + offset).powi(2))
+                .min_by(f64::total_cmp)
+                .unwrap();
+            family.weight * distance
+        })
+        .sum()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn enabled() -> Harmony {
+        Harmony {
+            enabled: true,
+            strength: 1.0,
+            ..Default::default()
+        }
+    }
+
+    #[test]
+    fn oklch_reference_roundtrips_and_gamut_reduction_preserve_lightness() {
+        let [l, c, h] = lch([255, 0, 0]);
+        assert!((l - 0.627955).abs() < 1e-5);
+        assert!((c - 0.257683).abs() < 1e-5);
+        assert!((h - 29.234).abs() < 0.01);
+        for rgb in [
+            [255, 0, 0],
+            [0, 255, 0],
+            [0, 0, 255],
+            [255; 3],
+            [0; 3],
+            [92, 113, 145],
+        ] {
+            assert_eq!(from_lch(lch(rgb)), rgb);
+        }
+        for hue in (0..360).step_by(15) {
+            let mapped = lch(from_lch([0.6, 0.4, hue as f64]));
+            assert!((mapped[0] - 0.6).abs() < 0.003);
+            assert!(mapped[1] < 0.4);
+            assert!(angle_delta(hue as f64, mapped[2]).abs() < 1.5);
+        }
+    }
+
+    #[test]
+    fn disabled_zero_strength_neutrals_and_alpha_are_preserved() {
+        let mut settings = enabled();
+        settings.rotation = 90.0;
+        let near_gray = from_lch([0.6, 0.015, 40.0]);
+        let pixels = [
+            255,
+            0,
+            0,
+            128,
+            100,
+            100,
+            100,
+            255,
+            near_gray[0],
+            near_gray[1],
+            near_gray[2],
+            255,
+            0,
+            0,
+            255,
+            0,
+        ];
+        let fit = Fit::new(
+            [([255, 0, 0], 1), ([100; 3], 100), (near_gray, 100)],
+            settings,
+        );
+        let result = fit.apply_rgba(&pixels, settings);
+        assert_ne!(&result[..3], &pixels[..3]);
+        assert_eq!(result[3], 128);
+        assert_eq!(&result[4..], &pixels[4..]);
+        assert_eq!(fit.apply_rgba(&pixels, Harmony::default()), pixels);
+        settings.strength = 0.0;
+        assert_eq!(fit.apply_rgba(&pixels, settings), pixels);
+        assert!(Fit::new([([128; 3], 100)], enabled()).families.is_empty());
+        assert!(Fit::new([], enabled()).families.is_empty());
+    }
+
+    #[test]
+    fn shading_and_local_hue_variation_survive_harmonization() {
+        let ramp: Vec<_> = [(0.35, 37.0), (0.55, 40.0), (0.75, 43.0)]
+            .into_iter()
+            .map(|(l, h)| from_lch([l, 0.07, h]))
+            .collect();
+        let settings = Harmony {
+            rotation: 95.0,
+            ..enabled()
+        };
+        let fit = Fit::new(ramp.iter().map(|&rgb| (rgb, 10)), settings);
+        assert_eq!(fit.families.len(), 1);
+        let output: Vec<_> = ramp
+            .iter()
+            .map(|&rgb| lch(fit.apply(rgb, settings)))
+            .collect();
+        for (&rgb, result) in ramp.iter().zip(&output) {
+            assert!((lch(rgb)[0] - result[0]).abs() < 0.004);
+            assert!((lch(rgb)[1] - result[1]).abs() < 0.004);
+        }
+        assert!(output[0][0] < output[1][0] && output[1][0] < output[2][0]);
+        assert!(angle_delta(output[0][2], output[2][2]) > 2.0);
+        assert!(angle_delta(lch(ramp[1])[2], output[1][2]).abs() > 80.0);
+        let mid = lch(fit.apply(
+            ramp[1],
+            Harmony {
+                strength: 0.5,
+                ..settings
+            },
+        ));
+        let arc = angle_delta(lch(ramp[1])[2], output[1][2]);
+        assert!((angle_delta(lch(ramp[1])[2], mid[2]) - arc / 2.0).abs() < 2.0);
+    }
+
+    #[test]
+    fn monochromatic_converges_to_one_hue_without_flattening_shading() {
+        let settings = Harmony {
+            scheme: Scheme::Monochromatic,
+            rotation: 35.0,
+            ..enabled()
+        };
+        let colors = [
+            from_lch([0.35, 0.07, 25.0]),
+            from_lch([0.55, 0.1, 145.0]),
+            from_lch([0.75, 0.08, 270.0]),
+        ];
+        let fit = Fit::new(colors.into_iter().map(|rgb| (rgb, 10)), settings);
+        for rgb in colors {
+            let output = lch(fit.apply(rgb, settings));
+            assert!(angle_delta(fit.orientation + settings.rotation, output[2]).abs() < 2.0);
+            assert!((lch(rgb)[0] - output[0]).abs() < 0.004);
+        }
+    }
+
+    #[test]
+    fn circular_families_and_fitting_are_deterministic() {
+        assert_eq!(angle_delta(359.0, 1.0), 2.0);
+        let colors = [
+            (from_lch([0.6, 0.12, 359.0]), 10),
+            (from_lch([0.6, 0.12, 1.0]), 10),
+        ];
+        let fit = Fit::new(colors, enabled());
+        assert_eq!(fit.families.len(), 1);
+        assert!(angle_delta(0.0, fit.families[0].hue).abs() < 3.0);
+        for scheme in Scheme::ALL {
+            let settings = Harmony {
+                scheme,
+                ..enabled()
+            };
+            let colors = [
+                (from_lch([0.6, 0.1, 65.0]), 10000),
+                (from_lch([0.6, 0.1, 230.0]), 50),
+                (from_lch([0.6, 0.1, 305.0]), 20),
+            ];
+            let fit = Fit::new(colors, settings);
+            let reverse = Fit::new(colors.into_iter().rev(), settings);
+            assert_eq!(fit.orientation, reverse.orientation);
+            assert!(
+                fit_cost(&fit.families, scheme, fit.orientation)
+                    <= fit_cost(&fit.families, scheme, 0.0)
+            );
+            assert!(fit.families.len() >= 3, "Keep small accents represented");
+            for family in &fit.families {
+                assert!(scheme.offsets().iter().any(|offset| {
+                    angle_delta(family.target, fit.orientation + offset).abs() < 1e-8
+                }));
+            }
+        }
+    }
+}
diff --git a/src/analysis/mapping.rs b/src/analysis/mapping.rs
index d58caf6..919d527 100644
--- a/src/analysis/mapping.rs
+++ b/src/analysis/mapping.rs
@@ -122,12 +122,15 @@ impl ColorMappings {
         self.0.last_mut().unwrap().target = target;
     }
 
-    pub fn apply_rgba(&self, rgba: &[u8]) -> Vec<u8> {
-        let lookup: HashMap<_, _> = self
-            .0
+    pub fn lookup(&self) -> HashMap<[u8; 3], [u8; 3]> {
+        self.0
             .iter()
             .flat_map(|entry| entry.members.iter().map(move |&rgb| (rgb, entry.target)))
-            .collect();
+            .collect()
+    }
+
+    pub fn apply_rgba(&self, rgba: &[u8]) -> Vec<u8> {
+        let lookup = self.lookup();
         let mut output = rgba.to_vec();
         for pixel in output.as_chunks_mut::<4>().0 {
             if pixel[3] != 0
diff --git a/src/analysis/mod.rs b/src/analysis/mod.rs
index f91ef1c..f343579 100644
--- a/src/analysis/mod.rs
+++ b/src/analysis/mod.rs
@@ -1,6 +1,7 @@
 //! Analysis always uses source pixels, never the scaled preview.
 use std::collections::HashMap;
 pub mod adjustments;
+pub mod harmony;
 pub mod mapping;
 pub mod vision;
 pub const LEVEL_BINS: usize = 20;
diff --git a/src/analysis/vision.rs b/src/analysis/vision.rs
index 969b78f..62e743b 100644
--- a/src/analysis/vision.rs
+++ b/src/analysis/vision.rs
@@ -86,7 +86,7 @@ fn decode(value: u8) -> f64 {
     }
 }
 
-fn encode(value: f64) -> u8 {
+pub(super) fn encode(value: f64) -> u8 {
     let value = value.clamp(0.0, 1.0);
     let value = if value <= 0.0031308 {
         value * 12.92
@@ -110,7 +110,7 @@ pub fn luminance(rgb: [u8; 3]) -> f64 {
 }
 
 // OKLab reference transform: https://bottosson.github.io/posts/oklab/
-fn oklab([r, g, b]: [f64; 3]) -> [f64; 3] {
+pub(super) fn oklab([r, g, b]: [f64; 3]) -> [f64; 3] {
     let l = (0.4122214708 * r + 0.5363325363 * g + 0.0514459929 * b).cbrt();
     let m = (0.2119034982 * r + 0.6806995451 * g + 0.1073969566 * b).cbrt();
     let s = (0.0883024619 * r + 0.2817188376 * g + 0.6299787005 * b).cbrt();
@@ -146,7 +146,7 @@ pub fn simulate_rgba(rgba: &[u8], mode: Vision) -> Vec<u8> {
 }
 
 pub const MAX_COLORS: usize = 64;
-#[derive(Debug)]
+#[derive(Clone, Debug, PartialEq)]
 pub struct PairWarning {
     pub a: [u8; 3],
     pub b: [u8; 3],
@@ -154,12 +154,13 @@ pub struct PairWarning {
     pub after: f64,
 }
 
+#[derive(Clone, Debug, PartialEq)]
 pub struct Scenario {
     pub mode: Vision,
     pub pairs: Vec<PairWarning>,
 }
 
-#[derive(Default)]
+#[derive(Clone, Debug, Default, PartialEq)]
 pub struct Report {
     pub scenarios: Vec<Scenario>,
     pub colors_checked: usize,
diff --git a/src/app.rs b/src/app.rs
index 3f19aa9..88a4f2c 100644
--- a/src/app.rs
+++ b/src/app.rs
@@ -3,6 +3,7 @@ use crate::{
     analysis::{
         self, Analysis, Region,
         adjustments::Adjustments,
+        harmony::{self, Harmony, Scheme},
         mapping::{ColorGroup, ColorMappings, group_palette},
         vision::{self, Vision},
     },
@@ -13,6 +14,20 @@ use crate::{
 use eframe::egui::{self, Color32};
 use std::time::{Duration, Instant};
 
+#[derive(Clone, Copy, PartialEq, Eq)]
+enum Sidebar {
+    Colors,
+    Vision,
+    Harmony,
+}
+
+#[derive(Clone, Copy)]
+enum Export {
+    Original,
+    Mapped,
+    Harmonized,
+}
+
 pub struct WhosHueApp {
     capture: Option<SharedCapture>,
     config: Config,
@@ -22,6 +37,10 @@ pub struct WhosHueApp {
     crop_texture: Option<egui::TextureHandle>,
     simulated_texture: Option<egui::TextureHandle>,
     vision_mode: Vision,
+    vision_preview: Vision,
+    edited_analysis: Option<Analysis>,
+    edited_palette_groups: Vec<ColorGroup>,
+    palette_source: bool,
     adjustments: Adjustments,
     mappings: ColorMappings,
     group_colors: bool,
@@ -30,7 +49,9 @@ pub struct WhosHueApp {
     hovered_group: Option<usize>,
     highlight_texture: Option<egui::TextureHandle>,
     mappings_enabled: bool,
-    vision_panel: bool,
+    sidebar_tab: Sidebar,
+    harmony: Harmony,
+    harmony_fit: harmony::Fit,
     channel: ui::Channel,
     region: Option<Region>,
     analysis: Analysis,
@@ -62,6 +83,10 @@ impl WhosHueApp {
             crop_texture: None,
             simulated_texture: None,
             vision_mode: Vision::Original,
+            vision_preview: Vision::Original,
+            edited_analysis: None,
+            edited_palette_groups: Vec::new(),
+            palette_source: false,
             adjustments: Adjustments::default(),
             mappings: ColorMappings::default(),
             group_colors: true,
@@ -70,7 +95,9 @@ impl WhosHueApp {
             hovered_group: None,
             highlight_texture: None,
             mappings_enabled: true,
-            vision_panel: false,
+            sidebar_tab: Sidebar::Colors,
+            harmony: Harmony::default(),
+            harmony_fit: harmony::Fit::default(),
             channel: ui::Channel::Hue,
             region: None,
             analysis: Analysis::default(),
@@ -95,6 +122,8 @@ impl WhosHueApp {
         // A new selection always opens KDE's picker; never silently restore it.
         self.capture = Some(capture::spawn(None));
         self.mappings = ColorMappings::default();
+        self.harmony = Harmony::default();
+        self.harmony_fit = harmony::Fit::default();
         self.mappings_enabled = true;
         self.frame = None;
         self.texture = None;
@@ -102,6 +131,9 @@ impl WhosHueApp {
         self.simulated_texture = None;
         self.region = None;
         self.analysis = Analysis::default();
+        self.edited_analysis = None;
+        self.edited_palette_groups.clear();
+        self.vision_preview = Vision::Original;
         self.rebuild_groups();
         self.frozen = false;
         self.drag_origin = None;
@@ -160,6 +192,7 @@ impl WhosHueApp {
                 region.height,
                 &pixels,
             );
+            self.refit_harmony();
             self.refresh_simulation(ctx);
         }
     }
@@ -177,6 +210,36 @@ impl WhosHueApp {
         self.highlight_texture = None;
     }
 
+    fn current_analysis(&self) -> &Analysis {
+        self.edited_analysis.as_ref().unwrap_or(&self.analysis)
+    }
+
+    fn displayed_groups(&self) -> &[ColorGroup] {
+        if self.palette_source || self.edited_analysis.is_none() {
+            &self.palette_groups
+        } else {
+            &self.edited_palette_groups
+        }
+    }
+
+    fn rebuild_edited_groups(&mut self) {
+        self.edited_palette_groups =
+            self.edited_analysis
+                .as_ref()
+                .map_or_else(Vec::new, |analysis| {
+                    group_palette(
+                        &analysis.palette,
+                        if self.group_colors {
+                            self.group_tolerance
+                        } else {
+                            0
+                        },
+                    )
+                });
+        self.hovered_group = None;
+        self.highlight_texture = None;
+    }
+
     fn highlight_group(&mut self, ctx: &egui::Context, index: Option<usize>) {
         if self.hovered_group == index {
             return;
@@ -187,7 +250,15 @@ impl WhosHueApp {
             && let Some(frame) = &self.frame
         {
             let region = self.region.unwrap_or_else(|| Region::full(frame));
-            let pixels = self.palette_groups[index].highlight_rgba(&region.crop(frame));
+            let crop = if self.palette_source {
+                region.crop(frame)
+            } else {
+                self.edited_crop(region, frame)
+            };
+            let Some(group) = self.displayed_groups().get(index) else {
+                return;
+            };
+            let pixels = group.highlight_rgba(&crop);
             Self::texture(
                 ctx,
                 &mut self.highlight_texture,
@@ -216,31 +287,89 @@ impl WhosHueApp {
         }
     }
 
+    fn harmony_active(&self) -> bool {
+        self.can_map() && self.harmony.enabled
+    }
+
+    fn refit_harmony(&mut self) {
+        if !self.harmony_active() {
+            return;
+        }
+        let lookup = if self.mappings_active() {
+            self.mappings.lookup()
+        } else {
+            Default::default()
+        };
+        self.harmony_fit = harmony::Fit::new(
+            self.analysis.palette.iter().map(|swatch| {
+                (
+                    *lookup.get(&swatch.rgb).unwrap_or(&swatch.rgb),
+                    swatch.count,
+                )
+            }),
+            self.harmony,
+        );
+    }
+
+    fn harmonized_crop(&self, region: Region, frame: &Frame) -> Vec<u8> {
+        let crop = self.mapped_crop(region, frame);
+        if self.harmony_active() {
+            self.harmony_fit.apply_rgba(&crop, self.harmony)
+        } else {
+            crop
+        }
+    }
+
+    fn export_pixels(&self, region: Region, frame: &Frame, kind: Export) -> Vec<u8> {
+        match kind {
+            Export::Original => region.crop(frame),
+            Export::Mapped => self.mapped_crop(region, frame),
+            Export::Harmonized => self.harmonized_crop(region, frame),
+        }
+    }
+
+    /// Pixels being checked, before the report's optional simulation overlay.
+    fn edited_crop(&self, region: Region, frame: &Frame) -> Vec<u8> {
+        let crop = self.harmonized_crop(region, frame);
+        if self.vision_mode == Vision::Original {
+            self.adjustments.apply_rgba(&crop)
+        } else {
+            vision::simulate_rgba(&crop, self.vision_mode)
+        }
+    }
+
     fn refresh_simulation(&mut self, ctx: &egui::Context) {
-        if self.vision_mode == Vision::Original
+        let Some(frame) = &self.frame else {
+            self.edited_analysis = None;
+            self.edited_palette_groups.clear();
+            self.simulated_texture = None;
+            return;
+        };
+        let region = self.region.unwrap_or_else(|| Region::full(frame));
+        let unchanged = self.vision_mode == Vision::Original
             && self.adjustments == Adjustments::default()
             && !self.mappings_active()
-        {
+            && !self.harmony_active();
+        if unchanged && self.vision_preview == Vision::Original {
+            self.edited_analysis = None;
+            self.edited_palette_groups.clear();
+            self.hovered_group = None;
+            self.highlight_texture = None;
             self.simulated_texture = None;
             return;
         }
-        if let Some(frame) = &self.frame {
-            let region = self.region.unwrap_or_else(|| Region::full(frame));
-            let crop = self.mapped_crop(region, frame);
-            let pixels = if self.vision_mode == Vision::Original {
-                self.adjustments.apply_rgba(&crop)
-            } else {
-                vision::simulate_rgba(&crop, self.vision_mode)
-            };
-            Self::texture(
-                ctx,
-                &mut self.simulated_texture,
-                "vision-preview",
-                region.width,
-                region.height,
-                &pixels,
-            );
-        }
+        let pixels = self.edited_crop(region, frame);
+        self.edited_analysis = (!unchanged).then(|| analysis::analyze(&pixels));
+        self.rebuild_edited_groups();
+        let pixels = vision::simulate_rgba(&pixels, self.vision_preview);
+        Self::texture(
+            ctx,
+            &mut self.simulated_texture,
+            "vision-preview",
+            region.width,
+            region.height,
+            &pixels,
+        );
     }
 
     fn load_image(&mut self, ctx: &egui::Context, path: &std::path::Path) {
@@ -252,10 +381,13 @@ impl WhosHueApp {
                     return;
                 }
                 self.stop();
+                self.vision_preview = Vision::Original;
                 self.region = None;
                 self.drag_origin = None;
                 self.frozen = true;
                 self.mappings = ColorMappings::default();
+                self.harmony = Harmony::default();
+                self.harmony_fit = harmony::Fit::default();
                 self.mappings_enabled = true;
                 self.set_frame(
                     ctx,
@@ -286,7 +418,7 @@ impl WhosHueApp {
         });
     }
 
-    fn export(&mut self, mapped: bool) {
+    fn export(&mut self, kind: Export) {
         if let Some(frame) = &self.frame {
             let r = self.region.unwrap_or_else(|| Region::full(frame));
             // Unique output preserves earlier captures.
@@ -297,11 +429,7 @@ impl WhosHueApp {
             let path = std::env::temp_dir().join(format!("whoshue-{stamp}.png"));
             self.message = match image::save_buffer(
                 &path,
-                &if mapped {
-                    self.mapped_crop(r, frame)
-                } else {
-                    r.crop(frame)
-                },
+                &self.export_pixels(r, frame, kind),
                 r.width,
                 r.height,
                 image::ColorType::Rgba8,
@@ -469,6 +597,18 @@ impl WhosHueApp {
         if previous_mode != self.vision_mode || previous_adjustments != self.adjustments {
             self.refresh_simulation(ui.ctx());
         }
+        if self.vision_preview != Vision::Original {
+            ui.horizontal_wrapped(|ui| {
+                ui.label(format!(
+                    "Vision-check preview: {}",
+                    self.vision_preview.label()
+                ));
+                if ui.button("Return to edited preview").clicked() {
+                    self.vision_preview = Vision::Original;
+                    self.refresh_simulation(ui.ctx());
+                }
+            });
+        }
         // Whole-image reset above may have changed the crop this frame.
         let region = self.region.unwrap_or(Region {
             x: 0,
@@ -489,9 +629,11 @@ impl WhosHueApp {
                     },
                 );
                 ui.small(if self.highlight_texture.is_some() {
-                    "Highlighted group · matching pixels shown in magenta"
+                    "Highlighted palette group · matching pixels shown in magenta"
+                } else if self.harmony_active() {
+                    "Harmonized preview · analysis uses edited colors · pixel inspection uses original colors"
                 } else if self.mappings_active() {
-                    "Mapped preview · pixel inspection and analysis use original colors"
+                    "Mapped preview · analysis uses edited colors · pixel inspection uses original colors"
                 } else {
                     "Pixel values and Save crop PNG use original colors"
                 });
@@ -560,7 +702,7 @@ impl WhosHueApp {
                     changed = true;
                 }
             });
-            ui.small("Choose Map beside a palette color or group.");
+            ui.small("Choose Source / map in the palette to map a color or group.");
             let mut remove = None;
             egui::ScrollArea::vertical()
                 .id_salt("mappings")
@@ -602,46 +744,137 @@ impl WhosHueApp {
                 )
                 .clicked()
             {
-                self.export(true);
+                self.export(Export::Mapped);
             }
         });
         if changed {
+            self.refit_harmony();
             self.refresh_simulation(ui.ctx());
         }
         ui.separator();
     }
 
+    fn harmony_controls(&mut self, ui: &mut egui::Ui) {
+        ui.heading("Harmonize the scene");
+        ui.label("Bring hue families together while keeping their shading.");
+        if !self.can_map() {
+            ui.small("Freeze the capture or open an image to harmonize its colors.");
+        }
+        let old = self.harmony;
+        let mut refit = false;
+        ui.add_enabled_ui(self.can_map(), |ui| {
+            ui.checkbox(&mut self.harmony.enabled, "Preview harmony")
+                .on_hover_text("Turn off to compare with the scene before harmonization.");
+            ui.horizontal_wrapped(|ui| {
+                for scheme in Scheme::ALL {
+                    ui.selectable_value(&mut self.harmony.scheme, scheme, scheme.label());
+                }
+            });
+            ui.small(self.harmony.scheme.description());
+            if old.scheme != self.harmony.scheme {
+                self.harmony.rotation = 0.0;
+                self.harmony.enabled = true;
+            }
+            ui.add(egui::Slider::new(&mut self.harmony.strength, 0.0..=1.0).text("Strength").custom_formatter(|n, _| format!("{:.0}%", n * 100.0)))
+                .on_hover_text("Zero preserves the input; full strength moves hue families into the selected harmony.");
+            ui.add(egui::Slider::new(&mut self.harmony.rotation, -180.0..=180.0).text("Rotation").suffix("°"));
+            ui.checkbox(&mut self.harmony.protect_neutrals, "Protect neutrals")
+                .on_hover_text("Keep near-gray pixels unchanged and gently transition to colored pixels.");
+            ui.horizontal(|ui| {
+                if ui.button("Auto fit").on_hover_text("Fit the current crop with as little hue movement as possible.").clicked() {
+                    self.harmony.enabled = true;
+                    self.harmony.rotation = 0.0;
+                    refit = true;
+                }
+                if ui.button("Reset harmony").clicked() {
+                    self.harmony = Harmony::default();
+                }
+            });
+        });
+        if refit
+            || old.scheme != self.harmony.scheme
+            || old.protect_neutrals != self.harmony.protect_neutrals
+            || (!old.enabled && self.harmony.enabled)
+        {
+            self.refit_harmony();
+        }
+        ui.add_enabled_ui(self.can_map(), |ui| {
+            ui::harmony_wheel(ui, &mut self.harmony, &self.harmony_fit);
+        });
+        if old != self.harmony || refit {
+            self.refresh_simulation(ui.ctx());
+        }
+        if self.harmony.enabled && self.can_map() && self.harmony_fit.families.is_empty() {
+            ui.label("No colored hue families to harmonize in this selection.");
+        }
+        ui.small("Drag the wheel to rotate. White dots show input hue families; spokes show the harmony targets.");
+        ui.small("Lightness is preserved as closely as possible. Very vivid colors may become less saturated to fit the display.");
+        if self.mappings_active() {
+            ui.small("Manual mappings are included before harmonization.");
+        }
+        if self.vision_mode != Vision::Original
+            || self.vision_preview != Vision::Original
+            || self.adjustments != Adjustments::default()
+        {
+            ui.small("A preview filter or adjustment is also selected.");
+            if ui.button("View harmony without filters").clicked() {
+                self.vision_mode = Vision::Original;
+                self.vision_preview = Vision::Original;
+                self.adjustments = Adjustments::default();
+                self.refresh_simulation(ui.ctx());
+            }
+        }
+        ui.small("Color analysis and vision check use the edited selection. Source preview and pixel inspection use original colors.");
+        if ui.add_enabled(self.harmony_active(), egui::Button::new("Save harmonized crop PNG"))
+            .on_hover_text("Includes active manual mappings and harmony, without preview filters or adjustments.").clicked() {
+            self.export(Export::Harmonized);
+        }
+    }
+
     fn sidebar(&mut self, ui: &mut egui::Ui) {
-        self.mapping_controls(ui);
-        ui.horizontal(|ui| {
-            ui.selectable_value(&mut self.vision_panel, false, "Color analysis");
+        ui.horizontal_wrapped(|ui| {
+            ui.selectable_value(&mut self.sidebar_tab, Sidebar::Colors, "Color analysis");
+            ui.selectable_value(&mut self.sidebar_tab, Sidebar::Harmony, "Harmonize");
             let count: usize = self
-                .analysis
+                .current_analysis()
                 .vision
                 .scenarios
                 .iter()
                 .map(|s| s.pairs.len())
                 .sum();
             ui.selectable_value(
-                &mut self.vision_panel,
-                true,
+                &mut self.sidebar_tab,
+                Sidebar::Vision,
                 format!("Vision check ({count})"),
             );
         });
         ui.separator();
-        if self.vision_panel {
+        if self.sidebar_tab == Sidebar::Harmony {
             self.highlight_group(ui.ctx(), None);
-            let old_mode = self.vision_mode;
+            egui::ScrollArea::vertical()
+                .id_salt("harmony_controls")
+                .show(ui, |ui| self.harmony_controls(ui));
+            return;
+        }
+        if self.sidebar_tab == Sidebar::Vision {
+            self.highlight_group(ui.ctx(), None);
+            let old_mode = self.vision_preview;
             egui::ScrollArea::vertical()
                 .id_salt("vision_warnings")
                 .show(ui, |ui| {
-                    ui::vision_report(ui, &self.analysis.vision, &mut self.vision_mode);
+                    let report = &self
+                        .edited_analysis
+                        .as_ref()
+                        .unwrap_or(&self.analysis)
+                        .vision;
+                    ui::vision_report(ui, report, &mut self.vision_preview);
                 });
-            if old_mode != self.vision_mode {
+            if old_mode != self.vision_preview {
                 self.refresh_simulation(ui.ctx());
             }
             return;
         }
+        self.mapping_controls(ui);
         ui.heading("Color distribution");
         ui.horizontal_wrapped(|ui| {
             for channel in ui::Channel::ALL {
@@ -652,16 +885,27 @@ impl WhosHueApp {
             ui.selectable_value(&mut self.distinct, false, "By pixel count");
             ui.selectable_value(&mut self.distinct, true, "By distinct color");
         });
-        ui::histogram(ui, &self.analysis, self.distinct, self.channel);
+        ui.small("Edited selection · includes mappings, harmony, and the selected filter or adjustments.");
+        ui::histogram(ui, self.current_analysis(), self.distinct, self.channel);
         if self.channel == ui::Channel::Hue {
             ui.label(format!(
                 "Neutrals: {} pixels / {} colors",
-                self.analysis.neutral_pixels, self.analysis.neutral_colors
+                self.current_analysis().neutral_pixels,
+                self.current_analysis().neutral_colors
             ));
         }
         ui.small(self.channel.description());
         ui.separator();
         ui.heading("Palette");
+        let previous_source = self.palette_source;
+        ui.horizontal(|ui| {
+            ui.selectable_value(&mut self.palette_source, false, "Edited");
+            ui.selectable_value(&mut self.palette_source, true, "Source / map");
+        });
+        if previous_source != self.palette_source {
+            self.hovered_group = None;
+            self.highlight_texture = None;
+        }
         let mut regroup = ui
             .checkbox(&mut self.group_colors, "Group similar colors")
             .changed();
@@ -671,13 +915,23 @@ impl WhosHueApp {
         }
         if regroup {
             self.rebuild_groups();
+            self.rebuild_edited_groups();
         }
-        ui.small("Hover a row to highlight matching pixels. Existing mappings keep their original shades.");
+        ui.small(if self.palette_source {
+            "Original colors for mapping · hover to highlight source pixels."
+        } else {
+            "Resulting colors · hover to highlight edited pixels. Use Source / map to choose replacements."
+        });
+        let palette_analysis = if self.palette_source {
+            &self.analysis
+        } else {
+            self.current_analysis()
+        };
         ui.label(format!(
             "{} groups / {} colors · {} pixels",
-            self.palette_groups.len(),
-            self.analysis.palette.len(),
-            self.analysis.pixels
+            self.displayed_groups().len(),
+            palette_analysis.palette.len(),
+            palette_analysis.pixels
         ));
         ui.small("Most frequent first · click a swatch to copy hex");
         let can_map = self.can_map();
@@ -687,10 +941,10 @@ impl WhosHueApp {
         egui::ScrollArea::vertical().id_salt("palette").show_rows(
             ui,
             24.0,
-            self.palette_groups.len(),
+            self.displayed_groups().len(),
             |ui, rows| {
                 for index in rows {
-                    let swatch = &self.palette_groups[index];
+                    let swatch = &self.displayed_groups()[index];
                     let row = ui.horizontal(|ui| {
                         let [r, g, b] = swatch.rgb;
                         let hex = format!("#{r:02X}{g:02X}{b:02X}");
@@ -703,13 +957,13 @@ impl WhosHueApp {
                         }
                         ui.monospace(&hex);
                         let already_mapped = self.mappings.0.iter().any(|entry| entry.members == swatch.members);
-                        if ui.add_enabled(can_map && !already_mapped, egui::Button::new(if already_mapped { "Mapped" } else { "Map" }))
+                        if self.palette_source && ui.add_enabled(can_map && !already_mapped, egui::Button::new(if already_mapped { "Mapped" } else { "Map" }))
                             .on_hover_text("Map every shade in this group. Overlapping colors move to this mapping.").clicked() {
                             map_color = Some(index);
                         }
                         ui.label(format!(
                             "{:.2}%",
-                            100.0 * swatch.count as f64 / self.analysis.pixels.max(1) as f64
+                            100.0 * swatch.count as f64 / palette_analysis.pixels.max(1) as f64
                         ));
                         ui.small(format!("{} shades", swatch.members.len()));
                         let [h, s, v] = analysis::hsv(swatch.rgb);
@@ -730,6 +984,7 @@ impl WhosHueApp {
         if let Some(index) = map_color {
             self.mappings.insert_group(&self.palette_groups[index]);
             self.mappings_enabled = true;
+            self.refit_harmony();
             self.refresh_simulation(ui.ctx());
         }
     }
@@ -785,17 +1040,19 @@ impl eframe::App for WhosHueApp {
                 .clicked()
             {
                 self.frozen = !self.frozen;
+                self.refit_harmony();
                 self.refresh_simulation(&ctx);
             }
             if ui
                 .add_enabled(has_frame, egui::Button::new("Save crop PNG"))
                 .clicked()
             {
-                self.export(false);
+                self.export(Export::Original);
             }
             if self.capture.is_some() && ui.button("Stop sharing").clicked() {
                 self.stop();
                 self.frozen = true;
+                self.refit_harmony();
                 self.refresh_simulation(&ctx);
             }
         });
@@ -846,6 +1103,282 @@ mod tests {
         }
     }
 
+    #[test]
+    fn color_analysis_and_palette_follow_edits_without_changing_mapping_sources() {
+        let ctx = egui::Context::default();
+        let mut app = WhosHueApp::empty(Config::default());
+        app.frozen = true;
+        app.set_frame(
+            &ctx,
+            Frame {
+                seq: 1,
+                width: 4,
+                height: 1,
+                rgba: vec![
+                    255, 0, 0, 255, 0, 255, 0, 128, 128, 128, 128, 255, 0, 0, 255, 0,
+                ],
+            },
+        );
+        app.mappings.insert([255, 0, 0], [0, 255, 0]);
+        app.refresh_simulation(&ctx);
+        let result = app.current_analysis();
+        assert_eq!(result.pixels, 3);
+        assert_eq!(result.palette.len(), 2);
+        assert_eq!(result.palette[0].rgb, [0, 255, 0]);
+        assert_eq!(result.palette[0].count, 2);
+        assert_eq!(result.hue_colors.iter().sum::<u64>(), 1);
+        assert_eq!(result.neutral_pixels, 1);
+        assert_eq!(app.displayed_groups()[0].rgb, [0, 255, 0]);
+        app.palette_source = true;
+        assert!(app.displayed_groups().iter().any(|g| g.rgb == [255, 0, 0]));
+        assert_eq!(app.analysis.palette.len(), 3);
+        app.palette_source = false;
+        app.adjustments.saturation = -100.0;
+        app.refresh_simulation(&ctx);
+        assert_eq!(app.current_analysis().neutral_pixels, 3);
+        assert_eq!(app.current_analysis().neutral_colors, 2);
+        assert_eq!(app.current_analysis().hue_pixels.iter().sum::<u64>(), 0);
+        let expected = analysis::analyze(&app.edited_crop(
+            Region::full(app.frame.as_ref().unwrap()),
+            app.frame.as_ref().unwrap(),
+        ));
+        for mode in Vision::CHECKS {
+            app.vision_preview = mode;
+            app.refresh_simulation(&ctx);
+            app.highlight_group(&ctx, Some(0));
+            let result = app.current_analysis();
+            assert_eq!(result.saturation.pixels, expected.saturation.pixels);
+            assert_eq!(result.saturation.colors, expected.saturation.colors);
+            assert_eq!(result.brightness.pixels, expected.brightness.pixels);
+            assert_eq!(result.brightness.colors, expected.brightness.colors);
+            assert_eq!(result.luminance.pixels, expected.luminance.pixels);
+            assert_eq!(result.luminance.colors, expected.luminance.colors);
+            assert_eq!(result.luminance.pixel_sum, expected.luminance.pixel_sum);
+        }
+        app.adjustments = Adjustments::default();
+        app.mappings_enabled = false;
+        app.refresh_simulation(&ctx);
+        assert!(app.edited_analysis.is_none());
+        assert_eq!(app.current_analysis().palette.len(), 3);
+        app.region = Some(Region {
+            x: 2,
+            y: 0,
+            width: 1,
+            height: 1,
+        });
+        app.analyze(&ctx);
+        assert_eq!(app.current_analysis().pixels, 1);
+        assert_eq!(app.current_analysis().neutral_pixels, 1);
+    }
+
+    #[test]
+    fn vision_check_tracks_mapping_toggles_and_selected_filters() {
+        let ctx = egui::Context::default();
+        let mut app = WhosHueApp::empty(Config::default());
+        app.frozen = true;
+        app.set_frame(
+            &ctx,
+            Frame {
+                seq: 1,
+                width: 3,
+                height: 1,
+                rgba: vec![255, 0, 0, 255, 0, 173, 0, 255, 0, 173, 0, 128],
+            },
+        );
+        let source_report = app.current_analysis().vision.clone();
+        assert!(source_report.scenarios.iter().any(|s| !s.pairs.is_empty()));
+        // Mapping the entire green family to red merges both opaque colors.
+        let group = app
+            .palette_groups
+            .iter()
+            .find(|g| g.rgb == [0, 173, 0])
+            .unwrap()
+            .clone();
+        app.mappings.insert_group(&group);
+        app.mappings.0[0].target = [255, 0, 0];
+        app.refresh_simulation(&ctx);
+        assert_eq!(app.current_analysis().vision.opaque_colors, 1);
+        assert_eq!(app.current_analysis().vision.opaque_pixels, 2);
+        assert!(
+            app.current_analysis()
+                .vision
+                .scenarios
+                .iter()
+                .all(|s| s.pairs.is_empty())
+        );
+        assert_eq!(app.analysis.vision, source_report);
+        app.mappings_enabled = false;
+        app.refresh_simulation(&ctx);
+        assert_eq!(app.current_analysis().vision, source_report);
+        app.adjustments.brightness = -100.0;
+        app.refresh_simulation(&ctx);
+        assert_eq!(app.current_analysis().vision.opaque_colors, 1);
+        assert!(
+            app.current_analysis()
+                .vision
+                .scenarios
+                .iter()
+                .all(|s| s.pairs.is_empty())
+        );
+        // Selected filters replace the adjustment sliders, as in the preview.
+        app.vision_mode = Vision::Invert;
+        app.refresh_simulation(&ctx);
+        let expected = analysis::analyze(&vision::simulate_rgba(
+            &app.frame.as_ref().unwrap().rgba,
+            Vision::Invert,
+        ))
+        .vision;
+        assert_eq!(app.current_analysis().vision, expected);
+        app.vision_mode = Vision::Original;
+        app.adjustments = Adjustments::default();
+        app.mappings_enabled = true;
+        app.frozen = false;
+        app.refresh_simulation(&ctx);
+        assert_eq!(app.current_analysis().vision, source_report);
+        app.frozen = true;
+        app.region = Some(Region {
+            x: 1,
+            y: 0,
+            width: 2,
+            height: 1,
+        });
+        app.analyze(&ctx);
+        assert_eq!(app.current_analysis().vision.opaque_pixels, 1);
+        assert_eq!(app.current_analysis().vision.opaque_colors, 1);
+    }
+
+    #[test]
+    fn vision_check_uses_harmony_but_excludes_diagnostic_overlays() {
+        let ctx = egui::Context::default();
+        let mut app = WhosHueApp::empty(Config::default());
+        app.frozen = true;
+        app.set_frame(
+            &ctx,
+            Frame {
+                seq: 1,
+                width: 2,
+                height: 1,
+                rgba: vec![255, 0, 0, 255, 0, 173, 0, 255],
+            },
+        );
+        app.harmony.enabled = true;
+        app.harmony.rotation = 70.0;
+        app.refit_harmony();
+        app.refresh_simulation(&ctx);
+        let frame = app.frame.as_ref().unwrap();
+        let edited = app.harmony_fit.apply_rgba(&frame.rgba, app.harmony);
+        assert_ne!(edited, frame.rgba);
+        let expected = analysis::analyze(&edited).vision;
+        assert_eq!(app.current_analysis().vision, expected);
+        for mode in Vision::CHECKS {
+            app.vision_preview = mode;
+            app.refresh_simulation(&ctx);
+            assert_eq!(app.current_analysis().vision, expected);
+            assert_eq!(app.vision_mode, Vision::Original);
+        }
+        app.highlight_group(&ctx, Some(0));
+        assert_eq!(app.current_analysis().vision, expected);
+        app.vision_preview = Vision::Original;
+        app.harmony.enabled = false;
+        app.refresh_simulation(&ctx);
+        assert_eq!(app.current_analysis().vision, app.analysis.vision);
+    }
+
+    #[test]
+    fn harmony_preview_export_and_lifecycle_preserve_source() {
+        let ctx = egui::Context::default();
+        let mut app = WhosHueApp::empty(Config::default());
+        app.frozen = true;
+        app.set_frame(&ctx, sample(1, 3));
+        app.harmony.enabled = true;
+        app.harmony.rotation = 90.0;
+        app.refit_harmony();
+        app.refresh_simulation(&ctx);
+        let frame = app.frame.as_ref().unwrap();
+        let region = Region::full(frame);
+        let expected = app.harmonized_crop(region, frame);
+        assert_ne!(expected, frame.rgba);
+        assert_eq!(
+            app.export_pixels(region, frame, Export::Original),
+            sample(1, 3).rgba
+        );
+        assert_eq!(
+            app.export_pixels(region, frame, Export::Mapped),
+            sample(1, 3).rgba
+        );
+        assert_eq!(app.analysis.palette[0].rgb, [255, 0, 0]);
+        app.vision_mode = Vision::Invert;
+        app.adjustments.hue = 45.0;
+        app.refresh_simulation(&ctx);
+        app.highlight_group(&ctx, Some(0));
+        app.export(Export::Harmonized);
+        let path = std::path::PathBuf::from(app.message.strip_prefix("Saved ").unwrap());
+        assert_eq!(image::open(&path).unwrap().to_rgba8().into_raw(), expected);
+        std::fs::remove_file(path).unwrap();
+        app.frozen = false;
+        assert_eq!(
+            app.harmonized_crop(region, app.frame.as_ref().unwrap()),
+            sample(1, 3).rgba
+        );
+        app.frozen = true;
+        app.region = Some(Region {
+            x: 0,
+            y: 0,
+            width: 1,
+            height: 1,
+        });
+        app.analyze(&ctx);
+        assert_eq!(app.simulated_texture.as_ref().unwrap().size(), [1, 1]);
+        assert!(app.highlight_texture.is_none());
+        assert_eq!(app.harmony.rotation, 90.0);
+        app.harmony.enabled = false;
+        app.vision_mode = Vision::Original;
+        app.adjustments = Adjustments::default();
+        app.refresh_simulation(&ctx);
+        assert!(app.simulated_texture.is_none());
+    }
+
+    #[test]
+    fn harmony_fits_manual_mappings_and_renders_all_presets() {
+        let ctx = egui::Context::default();
+        let mut app = WhosHueApp::empty(Config::default());
+        app.frozen = true;
+        app.set_frame(&ctx, sample(1, 2));
+        app.mappings.insert([255, 0, 0], [0, 0, 255]);
+        app.harmony.enabled = true;
+        app.harmony.rotation = 70.0;
+        app.sidebar_tab = Sidebar::Harmony;
+        for scheme in Scheme::ALL {
+            app.harmony.scheme = scheme;
+            app.refit_harmony();
+            app.refresh_simulation(&ctx);
+            let frame = app.frame.as_ref().unwrap();
+            let mapped = app.mapped_crop(Region::full(frame), frame);
+            assert_eq!(mapped, [0, 0, 255, 255].repeat(4));
+            assert_eq!(
+                app.harmonized_crop(Region::full(frame), frame),
+                app.harmony_fit.apply_rgba(&mapped, app.harmony)
+            );
+            assert_ne!(app.harmonized_crop(Region::full(frame), frame), mapped);
+            for size in [egui::vec2(1200.0, 800.0), egui::vec2(700.0, 450.0)] {
+                let mut output = ctx.run_ui(
+                    egui::RawInput {
+                        screen_rect: Some(egui::Rect::from_min_size(egui::Pos2::ZERO, size)),
+                        ..Default::default()
+                    },
+                    |ui| {
+                        egui::Panel::right("test_harmony_sidebar")
+                            .default_size(370.0)
+                            .show(ui, |ui| app.sidebar(ui));
+                        egui::CentralPanel::default().show(ui, |ui| app.preview(ui));
+                    },
+                );
+                assert!(!output.shapes.is_empty());
+                output.textures_delta.clear();
+            }
+        }
+    }
+
     #[test]
     fn grouped_preview_and_highlight_reset_when_recropping() {
         let ctx = egui::Context::default();
@@ -998,6 +1531,8 @@ mod tests {
         let path = std::env::temp_dir().join(format!("whoshue picker test ü {stamp}.png"));
         image::save_buffer(&path, &[0, 255, 0, 255], 1, 1, image::ColorType::Rgba8).unwrap();
         app.mappings.insert([255, 0, 0], [0, 0, 255]);
+        app.harmony.enabled = true;
+        app.harmony.rotation = 75.0;
         let (sender, receiver) = tokio::sync::oneshot::channel();
         app.file_picker = Some(receiver);
         sender.send(Ok(Some(path.clone()))).unwrap();
@@ -1008,6 +1543,8 @@ mod tests {
         assert!(app.capture.is_none());
         assert!(app.frozen);
         assert!(app.mappings.0.is_empty());
+        assert_eq!(app.harmony, Harmony::default());
+        assert!(app.harmony_fit.families.is_empty());
         assert_eq!(app.frame.as_ref().unwrap().rgba, [0, 255, 0, 255]);
     }
 
@@ -1089,7 +1626,11 @@ mod tests {
             for channel in ui::Channel::ALL {
                 app.channel = channel;
                 for warnings in [false, true] {
-                    app.vision_panel = warnings;
+                    app.sidebar_tab = if warnings {
+                        Sidebar::Vision
+                    } else {
+                        Sidebar::Colors
+                    };
                     let mut output = ctx.run_ui(
                         egui::RawInput {
                             screen_rect: Some(egui::Rect::from_min_size(
diff --git a/src/ui/mod.rs b/src/ui/mod.rs
index 2615d0a..b4aba48 100644
--- a/src/ui/mod.rs
+++ b/src/ui/mod.rs
@@ -149,6 +149,10 @@ fn swatch(ui: &mut egui::Ui, rgb: [u8; 3]) {
 pub fn vision_report(ui: &mut egui::Ui, report: &Report, preview: &mut Vision) {
     ui.heading("Color-vision check");
     ui.label("Potential color confusion, not an accessibility pass/fail.");
+    ui.small("Checking the edited selection: active mappings, harmony, and the selected filter or adjustments. Hover highlights and this check’s simulation previews are excluded.");
+    if *preview != Vision::Original && ui.button("Return to edited preview").clicked() {
+        *preview = Vision::Original;
+    }
     if report.colors_checked < 2 {
         ui.label("Select at least two opaque colors to check.");
         return;
@@ -169,6 +173,12 @@ pub fn vision_report(ui: &mut egui::Ui, report: &Report, preview: &mut Vision) {
     for scenario in &report.scenarios {
         ui.separator();
         ui.strong(scenario.mode.label());
+        if ui
+            .button(format!("Preview {}", scenario.mode.label()))
+            .clicked()
+        {
+            *preview = scenario.mode;
+        }
         if scenario.pairs.is_empty() {
             ui.label("No strong color-merging candidates in checked colors.");
             continue;
@@ -177,12 +187,6 @@ pub fn vision_report(ui: &mut egui::Ui, report: &Report, preview: &mut Vision) {
             "⚠ {} potentially confusing pairs",
             scenario.pairs.len()
         ));
-        if ui
-            .button(format!("Preview {}", scenario.mode.label()))
-            .clicked()
-        {
-            *preview = scenario.mode;
-        }
         for pair in scenario.pairs.iter().take(6) {
             ui.horizontal(|ui| {
                 swatch(ui, pair.a);
@@ -212,6 +216,54 @@ pub fn vision_report(ui: &mut egui::Ui, report: &Report, preview: &mut Vision) {
     }
 }
 
+/// The wheel uses the same OKLCH hue coordinates as fitting and recoloring.
+pub fn harmony_wheel(
+    ui: &mut egui::Ui,
+    settings: &mut crate::analysis::harmony::Harmony,
+    fit: &crate::analysis::harmony::Fit,
+) {
+    use crate::analysis::harmony::{angle_delta, from_lch};
+    let size = ui.available_width().min(180.0);
+    let (rect, response) =
+        ui.allocate_exact_size(egui::vec2(size, size), egui::Sense::click_and_drag());
+    let center = rect.center();
+    let radius = size * 0.43;
+    if (response.dragged() || response.clicked())
+        && let Some(pos) = response.interact_pointer_pos()
+    {
+        let offset = pos - center;
+        if offset.length() > radius * 0.3 {
+            let hue = offset.y.atan2(offset.x).to_degrees() as f64;
+            settings.rotation = angle_delta(fit.orientation, hue);
+        }
+    }
+    let point = |hue: f64, r: f32| {
+        center + egui::vec2(hue.to_radians().cos() as f32, hue.to_radians().sin() as f32) * r
+    };
+    let painter = ui.painter();
+    for hue in (0..360).step_by(3) {
+        let [r, g, b] = from_lch([0.72, 0.12, hue as f64]);
+        painter.line_segment(
+            [point(hue as f64, radius), point((hue + 3) as f64, radius)],
+            egui::Stroke::new(12.0, Color32::from_rgb(r, g, b)),
+        );
+    }
+    for family in &fit.families {
+        painter.circle_filled(point(family.hue, radius + 9.0), 3.0, Color32::WHITE);
+    }
+    for offset in settings.scheme.offsets() {
+        let hue = fit.orientation + settings.rotation + offset;
+        let [r, g, b] = from_lch([0.72, 0.12, hue]);
+        let color = Color32::from_rgb(r, g, b);
+        painter.line_segment(
+            [center, point(hue, radius - 10.0)],
+            egui::Stroke::new(2.0, color),
+        );
+        painter.circle_filled(point(hue, radius - 10.0), 5.0, color);
+    }
+    painter.circle_filled(center, 3.0, ui.visuals().text_color());
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;