Per-platform colour-border sensitivity (Teams violet, Meet glow)

Cross-platform research (Grant) flagged that the colour-border cue differs by app;
checking the real brand colours against the detector found a concrete bug: the
global 0.5 saturation threshold MISSES Teams' violet ring (#6264A7 ≈ 0.41, light
variants ~0.27) entirely and Meet's lighter blue glow (#8ab4f8 ≈ 0.44). Those
adapters would have detected nothing.

- FrameSampler.saturatedPoints: add a tunable threshold + optional hue-band gate
  (degrees) so a lowered threshold doesn't pick up warm video.
- GridCallAnalyzer.Config: colorSaturation / colorMinBrightness / colorHueRange,
  plumbed to the colour-border path (defaults preserve prior behaviour).
- MeetAdapter sat→0.35 (catch the glow); TeamsAdapter sat→0.22 + hue 215–275°
  (catch the faint violet, reject other colours); ZoomAdapter sat 0.45 + hue
  40–150° (vivid green/yellow). Values are first-pass pending real-fixture
  calibration; the hue gate is the main calibration lever.

Tests: Teams now detects the faint violet ring and rejects a green one; Meet/Zoom
vivid cases still pass. 27/27 XCTest.

Ten31Transcripts/Adapters/MeetAdapter.swift

@@ -27,8 +27,11 @@ struct MeetAdapter: AppAdapter {
     init() {
         var config = GridCallAnalyzer.Config()
         config.nameAnchor = .bottomLeft
-        config.detectColoredBorder = true     // Google-blue speaking ring
+        config.detectColoredBorder = true     // Google-blue speaking ring/glow
         config.detectWhiteBorder = false
+        // The bright ring (#1a73e8) is ~0.89 sat but the lighter glow (#8ab4f8) is
+        // ~0.44, below the 0.5 default — lower the threshold so the glow registers.
+        config.colorSaturation = 0.35
         config.tileExpandX = 3.0
         config.tileExpandY = 5.0
         self.analyzer = GridCallAnalyzer(config: config)

Ten31Transcripts/Adapters/TeamsAdapter.swift

@@ -20,8 +20,14 @@ struct TeamsAdapter: AppAdapter {
     init() {
         var config = GridCallAnalyzer.Config()
         config.nameAnchor = .bottomLeft
-        config.detectColoredBorder = true     // Teams-violet speaking ring
+        config.detectColoredBorder = true     // Teams-violet speaking ring (faint)
         config.detectWhiteBorder = false
+        // Teams' ring is muted: brand violet #6264A7 ≈ 0.41 sat, light variants
+        // ~0.27 — well under the 0.5 default, so the default misses it entirely.
+        // Drop the threshold and (since low sat invites warm-video false positives)
+        // gate to the violet/indigo hue band. Both pending real-fixture calibration.
+        config.colorSaturation = 0.22
+        config.colorHueRange = 215...275
         config.tileExpandX = 3.0
         config.tileExpandY = 5.0
         self.analyzer = GridCallAnalyzer(config: config)

Ten31Transcripts/Adapters/ZoomAdapter.swift

@@ -25,8 +25,13 @@ struct ZoomAdapter: AppAdapter {
     init() {
         var config = GridCallAnalyzer.Config()
         config.nameAnchor = .bottomLeft
-        config.detectColoredBorder = true     // green/yellow speaking border
+        config.detectColoredBorder = true     // green/yellow speaking border (vivid)
         config.detectWhiteBorder = false
+        // Zoom's frame is vivid (green #2d8c3c ≈ 0.68, yellow ≈ 0.96); the green→
+        // yellow hue band spans ~45–140°. Keep a generous-but-not-trivial threshold;
+        // require all-four-sides distribution (handled upstream) to reject bright video.
+        config.colorSaturation = 0.45
+        config.colorHueRange = 40...150
         config.tileExpandX = 3.0
         config.tileExpandY = 5.0
         self.analyzer = GridCallAnalyzer(config: config)

Ten31Transcripts/Visual/FrameSampler.swift

@@ -92,9 +92,14 @@ struct FrameSampler {
         return points
     }
 
-    /// Grid-sampled pixel positions (top-left origin) that are strongly saturated
-    /// AND bright enough to be a UI highlight — i.e. a coloured speaking ring/border.
-    func saturatedPoints(threshold: Double = 0.5, minBrightness: Double = 60, gridStep: Int = 6) -> [CGPoint] {
+    /// Grid-sampled pixel positions (top-left origin) that are saturated AND bright
+    /// enough to be a UI highlight — i.e. a coloured speaking ring/border. `threshold`
+    /// is the minimum saturation; lower it for muted accent rings (Teams violet,
+    /// Meet's light-blue glow sit below the 0.5 default). `hueRange`, when set,
+    /// additionally restricts to a hue band (degrees, 0…360) so a low threshold
+    /// doesn't pick up warm video — the per-platform calibration lever.
+    func saturatedPoints(threshold: Double = 0.5, minBrightness: Double = 60,
+                         hueRange: ClosedRange<Double>? = nil, gridStep: Int = 6) -> [CGPoint] {
         var points: [CGPoint] = []
         var y = 0
         while y < height {
@@ -104,11 +109,26 @@ struct FrameSampler {
                 let r = Double(pixels[i]), g = Double(pixels[i + 1]), b = Double(pixels[i + 2])
                 let mx = max(r, g, b), mn = min(r, g, b)
                 let sat = mx > 0 ? (mx - mn) / mx : 0
-                if sat > threshold && mx > minBrightness { points.append(CGPoint(x: x, y: y)) }
+                if sat > threshold && mx > minBrightness,
+                   hueRange == nil || hueRange!.contains(Self.hueDegrees(r, g, b, mx, mn)) {
+                    points.append(CGPoint(x: x, y: y))
+                }
                 x += gridStep
             }
             y += gridStep
         }
         return points
     }
+
+    /// HSV hue in degrees (0…360) from RGB and its precomputed max/min channels.
+    private static func hueDegrees(_ r: Double, _ g: Double, _ b: Double, _ mx: Double, _ mn: Double) -> Double {
+        let d = mx - mn
+        guard d > 0 else { return 0 }
+        let h: Double
+        if mx == r { h = (g - b) / d }
+        else if mx == g { h = 2 + (b - r) / d }
+        else { h = 4 + (r - g) / d }
+        let deg = h * 60
+        return deg < 0 ? deg + 360 : deg
+    }
 }

Ten31Transcripts/Visual/GridCallAnalyzer.swift

@@ -27,6 +27,14 @@ struct GridCallAnalyzer {
         var nameAnchor: NameAnchor = .bottomCenter
         var detectColoredBorder = true
         var detectWhiteBorder = true
+        // Coloured-border sensitivity. Default 0.5 suits vivid rings (Zoom green/
+        // yellow); lower it for muted accent rings (Teams violet ≈ 0.41, Meet's
+        // light-blue glow ≈ 0.44). `colorHueRange` (degrees) optionally pins the
+        // ring's hue so a low threshold doesn't catch warm video — set per platform
+        // once calibrated against real screenshots.
+        var colorSaturation: Double = 0.5
+        var colorMinBrightness: Double = 60
+        var colorHueRange: ClosedRange<Double>? = nil
         var minTextConfidence: Float = 0.3
         var maxNameLength = 40
         var minHighlightPoints = 6
@@ -58,7 +66,11 @@ struct GridCallAnalyzer {
 
         // Highlight pixels: coloured (saturated) and/or white (thin near-white).
         var highlight: [CGPoint] = []
-        if config.detectColoredBorder { highlight += sampler.saturatedPoints() }
+        if config.detectColoredBorder {
+            highlight += sampler.saturatedPoints(threshold: config.colorSaturation,
+                                                 minBrightness: config.colorMinBrightness,
+                                                 hueRange: config.colorHueRange)
+        }
         if config.detectWhiteBorder { highlight += sampler.thinWhitePoints() }
 
         // Drop points inside any name-text region so the white name itself doesn't count.

Ten31TranscriptsTests/GridCallAnalyzerTests.swift

@@ -117,6 +117,24 @@ final class GridCallAnalyzerTests: XCTestCase {
         XCTAssertEqual(speaking, ["ALEX"])
     }
 
+    func testTeamsDetectsFaintVioletRing() {
+        // Teams' brand violet #6264A7 is only ~0.41 saturation — below the 0.5
+        // default that Meet/Zoom inherited. The Teams adapter lowers the threshold,
+        // so it must still pick the ring.
+        let violet = CGColor(red: 0.384, green: 0.392, blue: 0.655, alpha: 1)
+        let obs = TeamsAdapter().analyze(cgImage: coloredFrame(speakingIndex: 2, border: violet), at: 0) // DMITRI
+        let speaking = Set(obs.filter { $0.speaking }.map { $0.name })
+        XCTAssertEqual(speaking, ["DMITRI"])
+    }
+
+    func testTeamsHueGateRejectsWrongColourBorder() {
+        // A green border (wrong hue for Teams) must NOT register — the violet hue
+        // gate is what keeps the lowered threshold from catching warm/other content.
+        let green = CGColor(red: 0.2, green: 0.85, blue: 0.3, alpha: 1)
+        let obs = TeamsAdapter().analyze(cgImage: coloredFrame(speakingIndex: 0, border: green), at: 0)
+        XCTAssertTrue(obs.filter { $0.speaking }.isEmpty)
+    }
+
     func testWhiteBorderDetectorIgnoresColouredBorder() {
         // Signal looks only for the white border, so a coloured (Meet) border must
         // not register as a Signal speaker.