fix(awareness): rest the range pulses unless the user moves the camera

Review follow-ups for the sonar pulses.

Wake on user input only: a camera move wakes the pulses only within
1.5 s of a pointer, wheel or touch on the Cesium canvas, where its
camera controller listens. Tracking, the cockpit view, an orbit or a
fly-to move the camera on every frame and no longer keep the pulses
running. Keys don't count: the camera controller reads none.

Below the disc: with the camera under 2.5 km the pulses rest
completely, with no disc, ring flash, echoes or frame requests.

Echo brightness: echoes scale by the contact bracket's drawn alpha,
which includes the Cyber sonar sweep, rounded to the nearest band with
no floor, so an echo is never brighter than its bracket.

Disc follow: the pulse disc follows the subject by a model-matrix
rotation about the Earth's centre and is rebuilt only every 20 km
instead of every 500 m.

Tests: a cap on burst length; teardown through disable(); the echo's
spread and alpha on the canvas; echoes under the Cyber sonar never
brighter than their bracket; waking by pointer, wheel, touch and drag
but not by keys, app camera moves or stale input; the rest below the
disc; and tighter asserts. CURRENT-STATE notes that terrain above
2.5 km still cuts through the disc and ring.

src/data/detection.js

@@ -1456,7 +1456,7 @@ function _drawOverlay(frame) {
           obj._layerId,
           obj.position,
           now,
-          admissionAlpha,
+          bracketAlpha,
           ECHO_ALPHA_STEPS,
         );
         if (echo)

src/data/detectionAwarenessEcho.test.mjs

@@ -39,8 +39,8 @@ test('the echo bracket pulses outward from the contact bracket and fades', (t) =
   setAwarenessEchoField(field);
   const position = Cesium.Cartesian3.fromDegrees(3.5, 27, 10_000);
   const arrival = arrivalAt(position);
-  const at = (nowMs, admissionAlpha = 1) =>
-    awarenessEchoBracket('flights', position, nowMs, admissionAlpha, STEPS);
+  const at = (nowMs, bracketAlpha = 1) =>
+    awarenessEchoBracket('flights', position, nowMs, bracketAlpha, STEPS);
 
   // The moment the front arrives: on the bracket, strongest band.
   const fresh = at(arrival);
@@ -53,8 +53,19 @@ test('the echo bracket pulses outward from the contact bracket and fades', (t) =
   assert.ok(half.spreadPx > echo.spreadPx * 0.5);
   assert.ok(half.spreadPx < echo.spreadPx);
   assert.ok(half.band < STEPS && half.band >= 1);
-  // Keyhole fade carries over to the echo.
-  assert.ok(at(arrival, 0.25).band <= 2);
+  // The bracket's own dimming (keyhole fade, Cyber sonar sweep) carries
+  // over, and the echo is never drawn brighter than its bracket: a bracket
+  // too dim for even one band draws no echo.
+  assert.equal(at(arrival, 0.25).band, 2);
+  assert.equal(at(arrival, 0.05), null);
+  for (let alpha = 0.05; alpha <= 1; alpha += 0.05) {
+    const echoed = at(arrival + echo.fadeMs / 3, alpha);
+    if (echoed)
+      assert.ok(
+        echoed.band / STEPS <= alpha + 0.5 / STEPS + 1e-9,
+        `band ${echoed.band} for a bracket at ${alpha}`,
+      );
+  }
   // Faded out, or between fronts: no echo bracket.
   assert.equal(at(arrival + echo.fadeMs + 5), null);
 });

src/data/detectionHost.test.mjs

@@ -54,8 +54,9 @@ class MockEvent {
 }
 
 class MockPath2D {
-  moveTo() {}
-  lineTo() {}
+  constructor() { this.points = []; }
+  moveTo(x, y) { this.points.push([x, y]); }
+  lineTo(x, y) { this.points.push([x, y]); }
   roundRect() {}
   arcTo() {}
   closePath() {}
@@ -102,7 +103,7 @@ function mockContext(target, trace) {
     // set at some point during the frame. globalAlpha rides along for the same
     // reason: the backdrop feather is an alpha, not a colour.
     fill(path) { record('fill', path, this.fillStyle, this.globalAlpha); },
-    stroke(path) { record('stroke', path, this.strokeStyle, this.lineWidth); },
+    stroke(path) { record('stroke', path, this.strokeStyle, this.lineWidth, this.globalAlpha); },
     fillRect(...args) { record('fillRect', ...args); },
     fillText(...args) { record('fillText', ...args); },
     drawImage(...args) { record('drawImage', ...args); },
@@ -680,6 +681,129 @@ test('Global Context echo brackets reach the canvas in the detection style colou
   }
 });
 
+test('a Global Context echo bracket is drawn outside its contact bracket and dimmer than it', () => {
+  const env = installEnvironment();
+  const echo = {
+    layerIds: ['military'],
+    fadeMs: 60_000,
+    color: 'rgb(1, 2, 3)',
+    spreadPx: 8,
+    lineWidth: 3.25,
+  };
+  // Fronts every millisecond keep the echo at full strength; a level of 0.5
+  // halves it, so it sits 4 px out and draws at half the bracket's alpha.
+  try {
+    setAwarenessEchoField({
+      center: Cesium.Cartesian3.fromDegrees(0, 89, 0),
+      radiusM: 250_000,
+      pulse: { count: 1000, periodMs: 1000, startFraction: 0 },
+      echo,
+      level: () => 0.5,
+    });
+    initWorldOverlay(env.viewer);
+    initDetection(env.viewer, [militaryLayer()], () => {});
+    setMode('DENSE');
+    setDetectionStyle('normal');
+    settleFrame(env);
+    env.detectionCtx.calls.length = 0;
+    settleFrame(env);
+    const strokes = env.detectionCtx.calls.filter(([name]) => name === 'stroke');
+    const echoStroke = strokes.find(([, , style, width]) => style === echo.color && width === echo.lineWidth);
+    assert.ok(echoStroke, 'the echo bracket is painted');
+    const bracketStroke = strokes.find(([, path, style, width]) =>
+      path instanceof MockPath2D && path.points.length && width !== echo.lineWidth && style !== echo.color);
+    assert.ok(bracketStroke, 'the contact bracket is painted');
+    const extent = (path) => {
+      const xs = path.points.map(([x]) => x);
+      const ys = path.points.map(([, y]) => y);
+      return { halfW: (Math.max(...xs) - Math.min(...xs)) / 2, halfH: (Math.max(...ys) - Math.min(...ys)) / 2 };
+    };
+    const echoBox = extent(echoStroke[1]);
+    const bracketBox = extent(bracketStroke[1]);
+    assert.ok(Math.abs(echoBox.halfW - bracketBox.halfW - echo.spreadPx / 2) < 1e-3,
+      `echo ${echoBox.halfW} vs bracket ${bracketBox.halfW}`);
+    assert.ok(Math.abs(echoBox.halfH - bracketBox.halfH - echo.spreadPx / 2) < 1e-3);
+    const echoAlpha = echoStroke[4];
+    const bracketAlpha = bracketStroke[4];
+    assert.ok(echoAlpha > 0 && echoAlpha < bracketAlpha, `${echoAlpha} vs ${bracketAlpha}`);
+    assert.ok(Math.abs(echoAlpha - bracketAlpha / 2) < 1e-6, `${echoAlpha} vs ${bracketAlpha}`);
+  } finally {
+    clearAwarenessEchoField();
+    env.cleanup();
+  }
+});
+
+test('under the Cyber sonar sweep an echo is never brighter than its own bracket', () => {
+  const env = installEnvironment();
+  // The cyber theme with its HUD open turns the contact sonar on; its sweep
+  // dims brackets it is not passing over.
+  env.document.documentElement = {
+    // The lowest sweep floor, so dimmed brackets drop a whole alpha band.
+    dataset: { uiTheme: 'cyber', cyberSonarOpacity: '35' },
+    style: { setProperty() {}, removeProperty() {} },
+  };
+  const hud = env.document.createElement('div');
+  hud.id = 'intel-hud';
+  hud.classList = { contains: (name) => name === 'active' };
+  env.document.body.appendChild(hud);
+  const echo = {
+    layerIds: ['military'],
+    fadeMs: 60_000,
+    color: 'rgb(1, 2, 3)',
+    spreadPx: 8,
+    lineWidth: 3.25,
+  };
+  const contact = {
+    id: 'military',
+    getDetectableObjects: () => [{
+      position: new Cesium.Cartesian3(0.5, 0.3, 6_356_752),
+      sourceId: 'sonar-pin',
+      id: 'SONAR',
+      metric: 'FL300',
+      type: 'AIR',
+      tier: 'military',
+    }],
+  };
+  try {
+    setAwarenessEchoField({
+      center: Cesium.Cartesian3.fromDegrees(0, 89, 0),
+      radiusM: 250_000,
+      pulse: { count: 1000, periodMs: 1000, startFraction: 0 },
+      echo,
+      level: () => 1,
+    });
+    initWorldOverlay(env.viewer);
+    initDetection(env.viewer, [contact], () => {});
+    setMode('DENSE');
+    setDetectionStyle('normal');
+    settleFrame(env);
+    let dimmed = 0;
+    let compared = 0;
+    for (let frame = 0; frame < 40; frame++) {
+      env.detectionCtx.calls.length = 0;
+      settleFrame(env);
+      const strokes = env.detectionCtx.calls.filter(([name]) => name === 'stroke');
+      const echoStroke = strokes.find(([, , style, width]) => style === echo.color && width === echo.lineWidth);
+      const bracketStroke = strokes.find(([, path, style, width]) =>
+        path instanceof MockPath2D && path.points.length && width !== echo.lineWidth && style !== echo.color);
+      if (!bracketStroke) continue;
+      const bracketAlpha = bracketStroke[4];
+      if (bracketAlpha < 0.99) dimmed++;
+      if (!echoStroke) continue;
+      compared++;
+      assert.ok(
+        echoStroke[4] <= bracketAlpha + 1e-9,
+        `echo ${echoStroke[4]} over bracket ${bracketAlpha} on frame ${frame}`,
+      );
+    }
+    assert.ok(dimmed > 0, 'the sweep dimmed the bracket on some frame');
+    assert.ok(compared > 0, 'an echo was painted');
+  } finally {
+    clearAwarenessEchoField();
+    env.cleanup();
+  }
+});
+
 test('resting Global Context pulses skip echo work for the whole frame, not per contact', () => {
   const env = installEnvironment();
   // Six echo-eligible flights on screen; the identity camera maps x/y
@@ -716,8 +840,8 @@ test('resting Global Context pulses skip echo work for the whole frame, not per
     settleFrame(env);
     levelCalls = 0;
     settleFrame(env);
-    const painted = getDetectionDiagnostics()?.visibleCount ?? flights.length;
-    assert.ok(painted >= 2, `contacts on screen: ${painted}`);
+    const painted = getDetectionDiagnostics().visibleCount;
+    assert.equal(painted, flights.length, 'every flight is on screen');
     // One check per painted frame, however many contacts are on screen.
     assert.ok(levelCalls >= 1, 'the frame asks whether echoes are live');
     assert.ok(levelCalls < painted, `${levelCalls} level checks for ${painted} contacts`);