feat(vessels): key vessels by their source's stable id, and share a selected vessel

AIS Vessels are keyed by the id their live source gives, with the MMSI as an
attribute: an MMSI can be shared, spoofed or reused, so two vessels with one
MMSI are now two vessels. Looking a vessel up or selecting it by MMSI still
finds it.

A share link made while a vessel is selected opens that vessel. A UUID vessel
id travels as 16 bytes in a new thing field (13). A shared thing that is not
reporting now says so in a sentence per kind, with its id (ICAO, NORAD, MMSI
or vessel UUID) on a second line.

changelog.d/0-contacts-follow-world-clock.md

@@ -3,5 +3,34 @@
   (`source.timeline`, read by `readSnapshotTimeline` from
   `gods-eye-view/sources/live`). Away from live they show the snapshot at the
   clock's time and move on with it as it plays; back at live they poll as
-  before. A source with no timeline keeps them live, unchanged (Sameh Khamis,
+  before. A source's `timeline.subscribe` may also tell of a better answer
+  for a time it has answered; paused, the layer loads the time shown again.
+  A source with no timeline keeps them live, unchanged (Sameh Khamis,
   @samehkhamis, #PR).
+- AIS Vessels are keyed by the stable id their live source gives (`id` on a
+  vessel record), not by MMSI: vessels can share an MMSI, through spoofing,
+  reused numbers or defaults such as 0, and a number can move to another
+  hull. Two vessels sharing an MMSI are now two vessels, each selected,
+  followed and carded on its own. The MMSI is an attribute (`mmsi`), shown
+  when known and `--` otherwise, up to ten digits; looking a vessel up or
+  selecting it by MMSI (an older link, say) still finds a vessel with it, and
+  a vessel with no name is no longer named by its id. `vesselSnapshot` takes
+  `idFor(row)` for a source whose rows carry an id of their own. Tool and voice results carry the vessel's id beside its MMSI
+  (`id`, or `vesselId` where `id` is a display label), and `get_vessel_track`
+  also takes an `id`. AISStream has only MMSIs, so its vessels are keyed by
+  MMSI and nothing changes there (Sameh Khamis, @samehkhamis, #PR).
+- A share link made while a vessel is selected (and the camera follows
+  nothing) now opens that vessel: the link names it, opens with the camera
+  where it was, looking at the vessel, and selects the vessel once the feed
+  has it, at the link's world time when it has one. A vessel id that is a
+  source's stable id, such as a UUID, travels as its 16 bytes in a new thing
+  field (13), so the link stays short (62 characters where a followed
+  aircraft's is 44). MMSI and other ids, and links already shared, are
+  unchanged; an app that predates the field opens such a link at the same
+  camera, without selecting the vessel. A camera that no follow offset can
+  carry (below the vessel's horizon, say) still makes a place view.
+  A shared flight, military flight, vessel or satellite that is not reporting
+  now says so in a sentence ("The shared vessel isn't reporting now — showing
+  where it was at 14:05"), with its id on a second line under it (ICAO,
+  NORAD, MMSI or vessel UUID) instead of at the head of the sentence (Sameh
+  Khamis, @samehkhamis, #PR).

docs/CODE-BOUNDARIES.md

@@ -634,8 +634,9 @@ source-time fallback and model-owned ground policy. The renderer supplies that
 ownership fact and handles stale-ground lifting, Cesium history and primitives;
 record reconciliation does not import the engine or application.
 
-`layers/vessels/records` owns plain AIS metadata, stable MMSI identity and bounded
-retention. `layers/vessels/ingestion` owns source requests and feed state through
+`layers/vessels/records` owns plain AIS metadata, identity by the stable id the
+source gives (an MMSI only for a feed that has nothing else; the MMSI itself is
+an attribute) and bounded retention. `layers/vessels/ingestion` owns source requests and feed state through
 explicit operations. Both exports exclude Cesium, DOM and application assembly.
 The snapshot renderer applies record changes; rendering owns a weak map of
 geometry and billboard resources used by cards, picking and trails.

docs/SHARE-LINK-FORMAT.md

@@ -28,7 +28,11 @@ Following an aircraft is 42–50: 42 when the link is made from the app's own
 follow camera with the fix taken as the link is made, 44 with a fix four
 seconds older, and 50 after orbiting to another heading and pitch. A view in
 any other style that keeps the style's own look adds only the style (two
-bytes): the 42-character followed aircraft in Noir is 44.
+bytes): the 42-character followed aircraft in Noir is 44. A selected vessel
+named by its MMSI costs what an aircraft does (46 characters for the
+44-character aircraft above); one named by a UUID costs 13 bytes more, as its
+16 bytes travel raw (62 characters where the aircraft is 44, rather than about
+88 with the UUID as text).
 
 ## Opening a short link
 
@@ -47,9 +51,22 @@ best effort: until the entity is found, and if it is not found in time, the
 camera is where the link was made, looking at the entity's last-known fix,
 and the app says that the entity isn't reporting and when the fix was taken.
 The share button makes a thing view while the camera follows an aircraft,
-military aircraft or satellite. A selected vessel is not followed (the camera
-stays where the user puts it), so a link made then is a place view; vessel
-thing views open, but the app does not make them yet.
+military aircraft or satellite. While the camera follows nothing and a vessel
+is selected, it makes a vessel thing view: the fix is the vessel's position
+as drawn (as of the world time while the vessel layer follows the world
+clock, else as of its latest position report), and the offset is the one whose derived camera is
+where the user's camera is (`followOffsetFor` in `src/share/follow.js`, the
+inverse of `followCameraFor`, taken from the fix at the format's precision).
+The opened camera is then within the offset's whole metres and degrees of
+where the link was made, looking at the vessel. When no offset can carry the
+camera, because it is not above the vessel's local horizontal (it would look
+up at the vessel, or through the earth) or its range is outside 1 m to
+10⁸ m, the link is a place view as before. A vessel is selected, not
+followed, so the camera stays where the user puts it. Following an entity
+takes priority over a selected vessel, and a followed entity the format
+cannot name still makes a place view. Opening a vessel thing view with a
+world time waits for the vessel layer's snapshot at that time and selects the
+vessel once it has it.
 
 ## Payload
 
@@ -274,14 +291,23 @@ sub-message:
 | 10  | fix alt     | sint metres                                              | 0       |
 | 11  | fix age     | sint seconds the fix predates the created-at time        | 0       |
 | 12  | observed-at | epoch, when the fix was taken; only without a created-at | none    |
+| 13  | vessel id   | UUID, 16 bytes (LEN)                                     |         |
 
 The entity kind is the field that carries the id (its code in
-`SHARE_VIEW_ENTITY_KINDS`), so it costs nothing; exactly one of fields 1–4 is
-present (two is malformed). Entity ids are the ones the layers look up: an
-aircraft's ICAO 24-bit address (six hex digits, stored as a number; other
-forms such as TIS-B `~abc123` as text), a vessel's MMSI and a satellite's
-NORAD catalog number (decimal numbers; an MMSI with a leading zero stays
-text). Ids are lowercase and match `[0-9a-z~_-]{1,16}`.
+`SHARE_VIEW_ENTITY_KINDS`, or field 13 for a vessel), so it costs nothing;
+exactly one of fields 1–4 and 13 is present (two is malformed). Entity ids are
+the ones the layers look up: an aircraft's ICAO 24-bit address (six hex
+digits, stored as a number; other forms such as TIS-B `~abc123` as text), a
+vessel's id (its MMSI, or a source's stable id, such as a UUID) and a
+satellite's NORAD catalog number (decimal numbers; an MMSI with a leading
+zero stays text). Ids are lowercase and match `[0-9a-z~_-]{1,16}`, except a
+vessel id that is a UUID (`xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx`, lowercase
+hex): it is written as its 16 bytes in field 13 rather than as 36 characters
+of text in field 3, after the other thing fields, and decodes as the
+lowercase dashed UUID. Field 13 of any other length is malformed. A decoder
+that predates field 13 skips it, finds no entity and opens the view as a
+place at its derived camera (`unknown-entity-kind`), as for a new entity kind,
+so the field needed no new version.
 
 Fields 5–7 are the follow offset: the camera looks along (heading, pitch) at
 the entity from `range` metres away, heading clockwise from north, in the
@@ -319,8 +345,9 @@ bytes, a check byte that does not match (`checksum`), an unknown version byte,
 a truncated value, a varint over 8 bytes or above 2⁵³ − 1, an
 overlong varint, a LEN longer than what remains (at any level, including
 inside the thing sub-message), a reserved wire type, field number 0, a known
-field with the wrong wire type or repeated, two entity ids in one thing, a
-duplicate panel/option/style entry, non-ASCII text, and a latitude or
+field with the wrong wire type or repeated, two entity ids in one thing
+(field 13 counts as one), a UUID vessel id that is not 16 bytes
+(`bad-length`), a duplicate panel/option/style entry, non-ASCII text, and a latitude or
 longitude (camera or fix) beyond ±90/±180.
 
 Tolerated and reported in `unknownFields`: unknown fields at any level
@@ -358,8 +385,8 @@ the app that can open it.
    boolean takes the next flag bit instead, which costs nothing when it is at
    its default.
 6. **New view kinds and entity kinds** get the next code. A new entity kind's
-   id takes the next free thing field (13 onwards), so older apps skip it and
-   fall back to the camera. A thing that needs more than an id (for example a
+   id takes the next free thing field (14 onwards; 13 is a vessel id that is
+   a UUID), so older apps skip it and fall back to the camera. A thing that needs more than an id (for example a
    CCTV camera, a radio station or a transit vehicle) adds further thing
    fields the same way.
 7. **A new layer option** needs an entry in `SHARE_VIEW_LAYER_OPTION_ABSENT`

docs/TOOLS.md

@@ -270,7 +270,7 @@ and the development server's internal routes. See SECURITY.md.
 | `get_aircraft_info`   | `aircraft`    | Aircraft type and registration, and flight route, from adsbdb  |
 | `vessels_in_area` | `vessels` | Ships reported by AIS in an area, nearest first, optionally by type; `group_by` and `stats` count and summarize every match |
 | `find_vessel` | `vessels` | Ships anywhere by MMSI, IMO number or name |
-| `get_vessel_track` | `vessels` | Recent positions of one ship, thinned to 200 points |
+| `get_vessel_track` | `vessels` | Recent positions of one ship by vessel id or MMSI, thinned to 200 points |
 | `next_satellite_pass` | `satellites` | Next pass over a place or point (default the ISS), with naked-eye visibility |
 | `satellites_overhead` | `satellites` | Satellites in a CelesTrak group above a place or point now, highest first |
 | `find_cctv_cameras` | `cctv` | Public cameras in an area, nearest first |

src/data/aisLiveVessels.analyst.test.mjs

@@ -6,6 +6,7 @@ import assert from 'node:assert/strict';
 import { mapAnalystRecord } from './aisLiveVessels.js';
 
 const FULL_RECORD = {
+  id: '353136000',
   mmsi: '353136000',
   name: 'EVER GIVEN',
   lat: 29.55,
@@ -20,6 +21,7 @@ test('ais analyst record: full record maps every contract field', () => {
   const r = mapAnalystRecord(FULL_RECORD);
   assert.deepEqual(r, {
     id: 'EVER GIVEN',
+    vesselId: '353136000',
     mmsi: '353136000',
     name: 'EVER GIVEN',
     lat: 29.55,
@@ -38,6 +40,16 @@ test('ais analyst record: nameless vessel falls back to mmsi id', () => {
   assert.equal(r.name, null);
 });
 
+test('ais analyst record: the key is the source id; the MMSI rides along when known', () => {
+  const shared = mapAnalystRecord({ ...FULL_RECORD, id: 'provider-a' });
+  assert.equal(shared.vesselId, 'provider-a');
+  assert.equal(shared.mmsi, '353136000');
+  const noMmsi = mapAnalystRecord({ ...FULL_RECORD, id: 'provider-b', mmsi: '', name: '' });
+  assert.equal(noMmsi.vesselId, 'provider-b');
+  assert.equal(noMmsi.mmsi, null);
+  assert.equal(noMmsi.id, 'provider-b', 'a nameless vessel with no MMSI is labelled by its id');
+});
+
 test('ais analyst record: empty strings and NaN become null, never undefined', () => {
   const r = mapAnalystRecord({ mmsi: '', name: 'TUG', speed: NaN, type: '', destination: '' });
   assert.equal(r.mmsi, null);

src/data/aisLiveVessels.test.mjs

@@ -287,7 +287,7 @@ test('zero accepted rows preserve warm vessel selection, trail, and freshness ti
     records: [record],
     selectedRecord: record,
     trail,
-    trailMmsi: record.mmsi,
+    trailId: record.mmsi,
     trailPositions: [POS],
     loaded: true,
     lastUpdate: 456,
@@ -314,8 +314,8 @@ test('zero accepted rows preserve warm vessel selection, trail, and freshness ti
       lastMessageAt: 789,
       rawRowCount: 1,
       acceptedRowCount: 0,
-      selectedMmsi: record.mmsi,
-      trailMmsi: record.mmsi,
+      selectedId: record.mmsi,
+      trailId: record.mmsi,
       trailPositionCount: 1,
       sessionId: _getVesselFeedStateForTest().sessionId,
       firstConnectPhase: 'idle',
@@ -565,7 +565,7 @@ test('superseded AIS response cannot mutate or finalize a replacement request',
       records: [replacement],
       selectedRecord: replacement,
       trail: replacementTrail,
-      trailMmsi: replacement.mmsi,
+      trailId: replacement.mmsi,
       trailPositions: [POS],
       loaded: true,
       lastUpdate: 200,
@@ -581,7 +581,7 @@ test('superseded AIS response cannot mutate or finalize a replacement request',
     let feed = _getVesselFeedStateForTest();
     assert.equal(feed.loading, true, 'old finally must not clear replacement loading ownership');
     assert.equal(feed.lastUpdate, 200, 'old response must not advance replacement freshness');
-    assert.equal(feed.selectedMmsi, replacement.mmsi);
+    assert.equal(feed.selectedId, replacement.mmsi);
 
     second.resolve(jsonResponse({ status: 'open', lastMessageAt: null, rows: [] }));
     await replacementLoad;
@@ -590,8 +590,8 @@ test('superseded AIS response cannot mutate or finalize a replacement request',
     assert.equal(feed.lastUpdate, 200);
     assert.equal(feed.error, 'awaiting first AIS message…');
     assert.equal(feed.stale, true);
-    assert.equal(feed.selectedMmsi, replacement.mmsi);
-    assert.equal(feed.trailMmsi, replacement.mmsi);
+    assert.equal(feed.selectedId, replacement.mmsi);
+    assert.equal(feed.trailId, replacement.mmsi);
     assert.equal(replacementTrail.clearCalls, 0);
   } finally {
     globalThis.fetch = priorFetch;
@@ -784,21 +784,21 @@ test('vessel focus wire restores a hidden sprite before releasing the active pas
 
 test('vessel selection: empty-space click requests deselection', () => {
   assert.deepEqual(
-    reduceVesselSelection({ selectedMmsi: '353136000', gesture: 'click' }),
+    reduceVesselSelection({ selectedId: '353136000', gesture: 'click' }),
     { action: 'deselect' },
   );
 });
 
 test('vessel selection: no selection plus empty-space click is a no-op', () => {
   assert.deepEqual(
-    reduceVesselSelection({ selectedMmsi: null, pickedMmsi: null, gesture: 'click' }),
+    reduceVesselSelection({ selectedId: null, pickedId: null, gesture: 'click' }),
     { action: 'none' },
   );
 });
 
 test('vessel selection: Escape deselects only when this layer owns a selection', () => {
   assert.deepEqual(
-    reduceVesselSelection({ selectedMmsi: 353136000, gesture: 'escape' }),
+    reduceVesselSelection({ selectedId: 353136000, gesture: 'escape' }),
     { action: 'deselect' },
   );
   assert.deepEqual(
@@ -810,16 +810,16 @@ test('vessel selection: Escape deselects only when this layer owns a selection',
 test('vessel selection: another vessel replaces selection; same vessel is a no-op', () => {
   assert.deepEqual(
     reduceVesselSelection({
-      selectedMmsi: '353136000',
-      pickedMmsi: '367123450',
+      selectedId: '353136000',
+      pickedId: '367123450',
       gesture: 'click',
     }),
     { action: 'select' },
   );
   assert.deepEqual(
     reduceVesselSelection({
-      selectedMmsi: '353136000',
-      pickedMmsi: '353136000',
+      selectedId: '353136000',
+      pickedId: '353136000',
       gesture: 'click',
     }),
     { action: 'none' },
@@ -834,8 +834,9 @@ test('vessel selection: another vessel replaces selection; same vessel is a no-o
 
 const POS = Cesium.Cartesian3.fromDegrees(4.05, 51.93, 3);
 
+// Like the layer's records, a vessel with no id of its own is keyed by its MMSI.
 function makeRecord(overrides = {}) {
-  return {
+  const record = {
     name: 'EVER GIVEN',
     mmsi: '353136000',
     type: 'Container Ship',
@@ -849,6 +850,8 @@ function makeRecord(overrides = {}) {
     billboard: null,
     ...overrides,
   };
+  if (!Object.hasOwn(overrides, 'id')) record.id = record.mmsi;
+  return record;
 }
 
 function makeTrailSpy() {
@@ -948,7 +951,7 @@ function installWireHarness(picked, stateOverrides = {}) {
     records: [record],
     selectedRecord: record,
     trail,
-    trailMmsi: record.mmsi,
+    trailId: record.mmsi,
     trailPositions: [POS],
     interactionHandlerFactory,
     interactionKeyTarget: keyTarget,
@@ -983,7 +986,7 @@ test('vessel interaction wire: trail pick does not deselect', () => {
     harness.handler.click({ position: { x: 10, y: 20 } });
     assert.equal(aisLiveVesselsLayer.getSelectedInfo()?.mmsi, harness.record.mmsi);
     assert.equal(harness.trail.clearCalls, 0);
-    assert.equal(_getVesselStateForTest().trailMmsi, harness.record.mmsi);
+    assert.equal(_getVesselStateForTest().trailId, harness.record.mmsi);
   } finally {
     harness.cleanup();
   }
@@ -1213,7 +1216,7 @@ test('vessel interaction lifecycle: disable detaches input and enable reinstalls
       selectedRecord: harness.record,
       enabled: false,
       trail: harness.trail,
-      trailMmsi: harness.record.mmsi,
+      trailId: harness.record.mmsi,
       trailPositions: [POS],
       interactionHandlerFactory: harness.interactionHandlerFactory,
       interactionKeyTarget: harness.keyTarget,
@@ -1287,7 +1290,7 @@ test('vessel trail lifecycle: deselect clears the selected-vessel trail', () =>
     aisLiveVesselsLayer.clearSelection();
     assert.equal(harness.trail.clearCalls, 1);
     assert.deepEqual(_getVesselStateForTest(), {
-      trailMmsi: null,
+      trailId: null,
       trailPositionCount: 0,
       vesselCount: 1,
     });
@@ -1302,14 +1305,14 @@ test('vessel trail lifecycle: reconciliation eviction clears an orphaned trail',
   _setVesselStateForTest({
     records: [record],
     trail,
-    trailMmsi: record.mmsi,
+    trailId: record.mmsi,
     trailPositions: [POS],
   });
   try {
     _reconcileVesselsForTest({}, []);
     assert.equal(trail.clearCalls, 1);
     assert.deepEqual(_getVesselStateForTest(), {
-      trailMmsi: null,
+      trailId: null,
       trailPositionCount: 0,
       vesselCount: 0,
     });
@@ -1566,6 +1569,28 @@ test('vessel interaction wire: selecting a vessel by click requests a camera tra
   }
 });
 
+test('vessel interaction wire: a vessel with an id and no MMSI is selected by click', () => {
+  const idOnly = makeRecord({ id: 'provider-7', mmsi: '', name: 'NO MMSI' });
+  const harness = installWireHarness(
+    { id: idOnly },
+    { records: [idOnly], selectedRecord: null, trailId: null },
+  );
+  const requests = [];
+  harness.windowTarget.addEventListener(
+    WORLD_FOCUS_REQUEST_EVENT,
+    (event) => requests.push(event.detail),
+  );
+  try {
+    harness.handler.click({ position: { x: 10, y: 20 } });
+    assert.equal(aisLiveVesselsLayer.getSelectedInfo()?.id, 'provider-7');
+    assert.equal(aisLiveVesselsLayer.getSelectedInfo()?.mmsi, '');
+    assert.equal(requests[0]?.id, 'provider-7');
+    assert.match(harness.hud.readout.text, /MMSI: -- /);
+  } finally {
+    harness.cleanup();
+  }
+});
+
 /**
  * Overlay-host recorder whose hitTest answers with one card id. The real host
  * only publishes rects for `interactive` entries, so a stub returning a hit is
@@ -1689,11 +1714,27 @@ for (const card of ['live', 'stale', 'absent', 'covered']) {
   });
 }
 
-test('vessel card policy: only MMSI-keyed cards publish a hit rect', () => {
+test('vessel card policy: only keyed cards publish a hit rect', () => {
   const keyed = applyVesselOverlayPolicy(buildVesselCard(makeRecord()));
   assert.equal(keyed.interactive, true);
   const unkeyed = applyVesselOverlayPolicy(buildVesselCard(makeRecord({ mmsi: '' })));
   assert.equal(unkeyed.interactive, false, 'an unkeyed card has no record to select');
+  const idOnly = buildVesselCard(makeRecord({ id: 'provider-7', mmsi: '' }));
+  assert.equal(applyVesselOverlayPolicy(idOnly).interactive, true, 'a source id is a key');
+  assert.equal(idOnly.id, 'vessel:provider-7');
+});
+
+test('vessel cards are keyed by id and show the MMSI only when known', () => {
+  const shared = buildSelectedVesselCard(makeRecord({ id: 'hull-b' }));
+  assert.equal(shared.id, 'vessel:hull-b');
+  assert.equal(shared.actionable, true);
+  assert.match(shared.details.at(-1), /^MMSI 353136000 · /);
+  const unknown = buildSelectedVesselCard(
+    makeRecord({ id: 'provider-7', mmsi: '', name: 'provider-7' }),
+  );
+  assert.equal(unknown.actionable, true);
+  assert.match(unknown.details.at(-1), /^MMSI -- · /);
+  assert.equal(unknown.title, 'VESSEL', 'a name that is only the id is no name');
 });
 
 test('vessel interaction wire: deselecting never moves the camera', () => {
@@ -1740,7 +1781,7 @@ test('vessel selection passes the opaque source reference to optional history',
     getSnapshot: async () => ({ records: [] }),
     getTrack: async (reference, options) => { requests.push({ reference, options }); return { records: [] }; },
   });
-  const harness = installWireHarness(undefined, { selectedRecord: null, trailMmsi: null });
+  const harness = installWireHarness(undefined, { selectedRecord: null, trailId: null });
   try {
     harness.record.reference = 'opaque:test-reference';
     assert.equal(aisLiveVesselsLayer.selectById(harness.record.mmsi), true);

src/data/firmsInteraction.test.mjs

@@ -276,7 +276,7 @@ test('a click on neither sprite nor card clears without moving the camera', () =
 const SIBLING_PICKS = [
   ['flights', 'a1b2c3', { id: 'a1b2c3' }],
   ['flights', 'a1b2c3', { primitive: { id: 'a1b2c3' } }],
-  ['ais-live-vessels', '353136000', { id: { mmsi: '353136000', name: 'EVER GIVEN' } }],
+  ['ais-live-vessels', '353136000', { id: { id: '353136000', mmsi: '353136000', name: 'EVER GIVEN' } }],
   ['cctv', 'atx-cam-3', { id: { id: 'atx-cam-3', name: 'entity-like' } }],
   ['satellites', '25544', { id: 25544 }],
 ];

src/data/militaryAwareness.test.mjs

@@ -1807,7 +1807,7 @@ test('hasContact declines while a layer is disabled, whatever its maps still hol
     [
       'aisLiveVessels',
       readLayerSource(new URL('./aisLiveVessels.js', import.meta.url)),
-      /hasContact\(\s*mmsi,?\s*\)\s*\{\s*\n\s*if\s*\(\s*!state\.feed\.enabled\s*\|\|\s*!state\.records\.byMmsi\s*\|\|\s*state\.records\.byMmsi\.size\s*===\s*0,?\s*\)\s*return\s*null;/,
+      /hasContact\(\s*id,?\s*\)\s*\{\s*\n\s*if\s*\(\s*!state\.feed\.enabled\s*\|\|\s*!state\.records\.byId\s*\|\|\s*state\.records\.byId\.size\s*===\s*0,?\s*\)\s*return\s*null;/,
     ],
   ]) {
     assert.match(

src/data/militaryAwarenessEngine.js

@@ -61,9 +61,9 @@ export function formatAwarenessLabel(value) {
       value.callsign,
       value.name,
       value.label,
+      value.mmsi,
       value.id,
       value.icao24,
-      value.mmsi,
     ]) {
       const label = formatAwarenessLabel(candidate);
       if (label !== '—') return label;
@@ -154,7 +154,7 @@ export function getAwarenessNavigationTargets(
         ? cohort.summary.nearest
         : [];
     for (const item of sourceItems) {
-      const id = item?.icao24 || item?.mmsi || item?.id;
+      const id = item?.icao24 || item?.id || item?.mmsi;
       if (!id) continue;
       const key = `${layerId}:${id}`;
       if (key === `${subject?.layerId}:${subject?.id}`) continue;

src/data/pickRegistry.js

@@ -21,7 +21,7 @@ const _owners = new Map();
  *
  * Layers use heterogeneous pick ids: flights/military/bikeshare/CCTV use
  * strings, satellites use numeric NORAD catalog ids, live AIS vessels attach
- * the vessel record OBJECT (identity = its `mmsi`), and entity picks surface
+ * the vessel record OBJECT (identity = its `id`), and entity picks surface
  * the Cesium Entity (identity = its string `id`). Everything is coerced to a
  * String so predicates match against one canonical form.
  *
@@ -33,9 +33,7 @@ export function resolvePickId(picked) {
   const unwrap = (id) => {
     if (id === null || id === undefined) return undefined;
     if (typeof id === 'object') {
-      // AIS vessel record (id object with .mmsi) or Cesium Entity (.id string)
-      if (typeof id.mmsi === 'string' || typeof id.mmsi === 'number')
-        return id.mmsi;
+      // AIS vessel record or Cesium Entity: both are keyed by their `.id`.
       if (typeof id.id === 'string' || typeof id.id === 'number') return id.id;
       return undefined;
     }

src/data/pickRegistry.test.mjs

@@ -33,10 +33,12 @@ test('resolvePickId: numeric pick id (satellite NORAD numbers) → String', () =
   assert.equal(resolvePickId({ id: undefined, primitive: { id: 43013 } }), '43013');
 });
 
-test('resolvePickId: AIS vessel record object → its mmsi', () => {
-  const record = { mmsi: '367123450', name: 'EVER GIVEN', billboard: {} };
+test('resolvePickId: AIS vessel record object → its id, not its MMSI', () => {
+  const record = { id: '367123450', mmsi: '367123450', name: 'EVER GIVEN', billboard: {} };
   assert.equal(resolvePickId({ id: record }), '367123450');
   assert.equal(resolvePickId({ primitive: { id: record } }), '367123450');
+  const shared = { id: 'hull-b', mmsi: '367123450', name: 'EVER GIVEN' };
+  assert.equal(resolvePickId({ id: shared }), 'hull-b');
 });
 
 test('resolvePickId: Cesium-Entity-like object → its string id', () => {
@@ -48,7 +50,7 @@ test('resolvePickId: unresolvable picks → null', () => {
   assert.equal(resolvePickId(null), null);
   assert.equal(resolvePickId(undefined), null);
   assert.equal(resolvePickId({}), null);
-  assert.equal(resolvePickId({ id: {} }), null); // object with no mmsi/id
+  assert.equal(resolvePickId({ id: {} }), null); // object with no id
   assert.equal(resolvePickId({ primitive: {} }), null);
 });
 
@@ -67,8 +69,8 @@ test('ownership: sibling layers recognize each other via String-coerced ids', ()
   try {
     // Flights asking about a satellite pick (raw numeric id → String upstream)
     assert.equal(isOwnedByOtherLayer('flights', resolvePickId({ id: 25544 })), true);
-    // Flights asking about a vessel pick (record object → mmsi)
-    assert.equal(isOwnedByOtherLayer('flights', resolvePickId({ id: { mmsi: '367123450' } })), true);
+    // Flights asking about a vessel pick (record object → id)
+    assert.equal(isOwnedByOtherLayer('flights', resolvePickId({ id: { id: '367123450', mmsi: '367123450' } })), true);
     // A layer never owns its own pick via the sibling scan
     assert.equal(isOwnedByOtherLayer('satellites', '25544'), false);
     // Unknown ids belong to nobody
@@ -147,7 +149,7 @@ test('touch contact pick expands only a surface miss, bounded to 8 hits in 14 CS
 test('touch contact pick returns the first registered sibling, never a caller-specific preference', (t) => {
   primaryPointer(t, true);
   contactOwners(t);
-  for (const first of [{ id: 'military' }, { id: { mmsi: '123456789' } }]) {
+  for (const first of [{ id: 'military' }, { id: { id: '123456789', mmsi: '123456789' } }]) {
     const scene = {
       pick: () => mapTile,
       drillPick: () => [mapTile, first, { id: 'civil' }],

src/data/pickedContext.js

@@ -64,8 +64,8 @@ function contextCarrierRecord(picked, dataManager) {
 function fromRecord(record) {
   const layerId = record.layerId || null;
   const id =
-    layerId === 'ais-live-vessels' && record.properties?.mmsi
-      ? String(record.properties.mmsi)
+    layerId === 'ais-live-vessels' && record.properties?.vesselId
+      ? String(record.properties.vesselId)
       : String(record.id);
   return {
     layerId,

src/data/vesselLabels.js

@@ -155,7 +155,7 @@ export function applyVesselOverlayPolicy(
     edgeFade: 'keyhole',
     horizonCull: true,
     terrainOcclusion: false,
-    // Only MMSI-keyed cards can resolve back to one actionable vessel.
+    // Only keyed cards can resolve back to one actionable vessel.
     interactive: card?.actionable === true,
   };
 }

src/i18n/locales/ar.json

@@ -2676,8 +2676,6 @@
   "Shared flight is unavailable": "الرحلة المشتركة غير متاحة",
   "Shared military flight is unavailable": "الرحلة العسكرية المشتركة غير متاحة",
   "Shared satellite is unavailable": "القمر الصناعي المشترك غير متاح",
-  "{id} isn't reporting now — showing where it was last seen": "{id}: لا بيانات واردة الآن — يُعرض آخر موضع معروف",
-  "{id} isn't reporting now — showing where it was at {time}": "{id}: لا بيانات واردة الآن — يُعرض الموضع عند {time}",
   "This share link can't be opened": "لا يمكن فتح رابط المشاركة هذا",
   "Shared vessel is unavailable": "السفينة المشتركة غير متاحة",
   "subject": "الهدف",
@@ -3778,5 +3776,17 @@
   "Play speed": "سرعة التشغيل",
   "Scroll or pinch to zoom, drag to move along · double-click to see it all": "مرّر أو اقرص للتكبير، واسحب للتنقل · انقر نقرًا مزدوجًا لرؤية الكل",
   "1 min/s": "دقيقة/ث",
-  "Photo © {photographer}": "صورة © {photographer}"
+  "Photo © {photographer}": "صورة © {photographer}",
+  "The shared flight isn't reporting now — showing where it was last seen": "الرحلة المشتركة: لا بيانات واردة الآن — يُعرض آخر موضع معروف",
+  "The shared flight isn't reporting now — showing where it was at {time}": "الرحلة المشتركة: لا بيانات واردة الآن — يُعرض موضعها عند {time}",
+  "The shared military flight isn't reporting now — showing where it was last seen": "الرحلة العسكرية المشتركة: لا بيانات واردة الآن — يُعرض آخر موضع معروف",
+  "The shared military flight isn't reporting now — showing where it was at {time}": "الرحلة العسكرية المشتركة: لا بيانات واردة الآن — يُعرض موضعها عند {time}",
+  "The shared vessel isn't reporting now — showing where it was last seen": "السفينة المشتركة: لا بيانات واردة الآن — يُعرض آخر موضع معروف",
+  "The shared vessel isn't reporting now — showing where it was at {time}": "السفينة المشتركة: لا بيانات واردة الآن — يُعرض موضعها عند {time}",
+  "The shared satellite isn't reporting now — showing where it was last seen": "القمر الصناعي المشترك: لا بيانات واردة الآن — يُعرض آخر موضع معروف",
+  "The shared satellite isn't reporting now — showing where it was at {time}": "القمر الصناعي المشترك: لا بيانات واردة الآن — يُعرض موضعها عند {time}",
+  "ICAO: {id}": "ICAO: {id}",
+  "NORAD: {id}": "NORAD: {id}",
+  "MMSI: {id}": "MMSI: {id}",
+  "Vessel UUID: {id}": "معرّف UUID للسفينة: {id}"
 }

src/i18n/locales/de.json

@@ -2528,8 +2528,6 @@
   "Shared flight is unavailable": "Geteilter Flug ist nicht verfügbar",
   "Shared military flight is unavailable": "Geteilter Militärflug ist nicht verfügbar",
   "Shared satellite is unavailable": "Geteilter Satellit ist nicht verfügbar",
-  "{id} isn't reporting now — showing where it was last seen": "{id} sendet gerade nicht – letzte bekannte Position wird gezeigt",
-  "{id} isn't reporting now — showing where it was at {time}": "{id} sendet gerade nicht – Position um {time} wird gezeigt",
   "This share link can't be opened": "Dieser Freigabelink kann nicht geöffnet werden",
   "Shared vessel is unavailable": "Geteiltes Schiff ist nicht verfügbar",
   "subject": "Objekt",
@@ -3454,5 +3452,17 @@
   "Play speed": "Wiedergabegeschwindigkeit",
   "Scroll or pinch to zoom, drag to move along · double-click to see it all": "Scrollen oder mit zwei Fingern zoomen, ziehen zum Verschieben · Doppelklick zeigt alles",
   "1 min/s": "1 Min./s",
-  "Photo © {photographer}": "Foto © {photographer}"
+  "Photo © {photographer}": "Foto © {photographer}",
+  "The shared flight isn't reporting now — showing where it was last seen": "Der geteilte Flug sendet gerade nicht – letzte bekannte Position wird gezeigt",
+  "The shared flight isn't reporting now — showing where it was at {time}": "Der geteilte Flug sendet gerade nicht – Position um {time} wird gezeigt",
+  "The shared military flight isn't reporting now — showing where it was last seen": "Der geteilte Militärflug sendet gerade nicht – letzte bekannte Position wird gezeigt",
+  "The shared military flight isn't reporting now — showing where it was at {time}": "Der geteilte Militärflug sendet gerade nicht – Position um {time} wird gezeigt",
+  "The shared vessel isn't reporting now — showing where it was last seen": "Das geteilte Schiff sendet gerade nicht – letzte bekannte Position wird gezeigt",
+  "The shared vessel isn't reporting now — showing where it was at {time}": "Das geteilte Schiff sendet gerade nicht – Position um {time} wird gezeigt",
+  "The shared satellite isn't reporting now — showing where it was last seen": "Der geteilte Satellit sendet gerade nicht – letzte bekannte Position wird gezeigt",
+  "The shared satellite isn't reporting now — showing where it was at {time}": "Der geteilte Satellit sendet gerade nicht – Position um {time} wird gezeigt",
+  "ICAO: {id}": "ICAO: {id}",
+  "NORAD: {id}": "NORAD: {id}",
+  "MMSI: {id}": "MMSI: {id}",
+  "Vessel UUID: {id}": "Schiffs-UUID: {id}"
 }

src/i18n/locales/es.json

@@ -427,8 +427,6 @@
   "Link copied!": "¡Enlace copiado!",
   "Link shared": "Enlace compartido",
   "This share link can't be opened": "Este enlace compartido no se puede abrir",
-  "{id} isn't reporting now — showing where it was at {time}": "{id} no está transmitiendo ahora; se muestra dónde estaba a las {time}",
-  "{id} isn't reporting now — showing where it was last seen": "{id} no está transmitiendo ahora; se muestra dónde se vio por última vez",
   "Shared vessel is unavailable": "El buque compartido no está disponible",
   "Copy failed": "No se pudo copiar",
   "Location not found": "Ubicación no encontrada",
@@ -3535,5 +3533,17 @@
   "Play speed": "Velocidad de reproducción",
   "Scroll or pinch to zoom, drag to move along · double-click to see it all": "Desplaza o pellizca para ampliar, arrastra para moverte · doble clic para verlo todo",
   "1 min/s": "1 min/s",
-  "Photo © {photographer}": "Foto © {photographer}"
+  "Photo © {photographer}": "Foto © {photographer}",
+  "The shared flight isn't reporting now — showing where it was last seen": "El vuelo compartido no está transmitiendo ahora; se muestra dónde se vio por última vez",
+  "The shared flight isn't reporting now — showing where it was at {time}": "El vuelo compartido no está transmitiendo ahora; se muestra dónde estaba a las {time}",
+  "The shared military flight isn't reporting now — showing where it was last seen": "El vuelo militar compartido no está transmitiendo ahora; se muestra dónde se vio por última vez",
+  "The shared military flight isn't reporting now — showing where it was at {time}": "El vuelo militar compartido no está transmitiendo ahora; se muestra dónde estaba a las {time}",
+  "The shared vessel isn't reporting now — showing where it was last seen": "El buque compartido no está transmitiendo ahora; se muestra dónde se vio por última vez",
+  "The shared vessel isn't reporting now — showing where it was at {time}": "El buque compartido no está transmitiendo ahora; se muestra dónde estaba a las {time}",
+  "The shared satellite isn't reporting now — showing where it was last seen": "El satélite compartido no está transmitiendo ahora; se muestra dónde se vio por última vez",
+  "The shared satellite isn't reporting now — showing where it was at {time}": "El satélite compartido no está transmitiendo ahora; se muestra dónde estaba a las {time}",
+  "ICAO: {id}": "ICAO: {id}",
+  "NORAD: {id}": "NORAD: {id}",
+  "MMSI: {id}": "MMSI: {id}",
+  "Vessel UUID: {id}": "UUID del buque: {id}"
 }

src/i18n/locales/fr.json

@@ -2287,8 +2287,6 @@
   "Shared {subject} follow expired": "Suivi partagé expiré : {subject}",
   "Shared {subject} could not be restored — feed unavailable": "Suivi partagé non restauré : {subject} — flux indisponible",
   "Shared {subject} is unavailable": "Partage indisponible : {subject}",
-  "{id} isn't reporting now — showing where it was last seen": "{id} n'émet pas actuellement — affichage de sa dernière position connue",
-  "{id} isn't reporting now — showing where it was at {time}": "{id} n'émet pas actuellement — affichage de sa position à {time}",
   "This share link can't be opened": "Ce lien de partage ne peut pas être ouvert",
   "Shared vessel is unavailable": "Le navire partagé est indisponible",
   "ACQUIRING": "ACQUISITION",
@@ -3535,5 +3533,17 @@
   "Play speed": "Vitesse de lecture",
   "Scroll or pinch to zoom, drag to move along · double-click to see it all": "Faites défiler ou pincez pour zoomer, glissez pour vous déplacer · double-clic pour tout voir",
   "1 min/s": "1 min/s",
-  "Photo © {photographer}": "Photo © {photographer}"
+  "Photo © {photographer}": "Photo © {photographer}",
+  "The shared flight isn't reporting now — showing where it was last seen": "Le vol partagé n'émet pas actuellement — affichage de sa dernière position connue",
+  "The shared flight isn't reporting now — showing where it was at {time}": "Le vol partagé n'émet pas actuellement — affichage de sa position à {time}",
+  "The shared military flight isn't reporting now — showing where it was last seen": "Le vol militaire partagé n'émet pas actuellement — affichage de sa dernière position connue",
+  "The shared military flight isn't reporting now — showing where it was at {time}": "Le vol militaire partagé n'émet pas actuellement — affichage de sa position à {time}",
+  "The shared vessel isn't reporting now — showing where it was last seen": "Le navire partagé n'émet pas actuellement — affichage de sa dernière position connue",
+  "The shared vessel isn't reporting now — showing where it was at {time}": "Le navire partagé n'émet pas actuellement — affichage de sa position à {time}",
+  "The shared satellite isn't reporting now — showing where it was last seen": "Le satellite partagé n'émet pas actuellement — affichage de sa dernière position connue",
+  "The shared satellite isn't reporting now — showing where it was at {time}": "Le satellite partagé n'émet pas actuellement — affichage de sa position à {time}",
+  "ICAO: {id}": "ICAO : {id}",
+  "NORAD: {id}": "NORAD : {id}",
+  "MMSI: {id}": "MMSI : {id}",
+  "Vessel UUID: {id}": "UUID du navire : {id}"
 }

src/i18n/locales/he.json

@@ -2119,8 +2119,6 @@
   "Shared {subject} follow expired": "עקיבת {subject} המשותף פגה",
   "Shared {subject} could not be restored — feed unavailable": "לא ניתן לשחזר את {subject} המשותף — הפיד אינו זמין",
   "Shared {subject} is unavailable": "{subject} המשותף אינו זמין",
-  "{id} isn't reporting now — showing where it was last seen": "{id} לא מדווח עכשיו — מציג היכן נראה לאחרונה",
-  "{id} isn't reporting now — showing where it was at {time}": "{id} לא מדווח עכשיו — מציג היכן היה ב-{time}",
   "This share link can't be opened": "לא ניתן לפתוח את קישור השיתוף הזה",
   "Shared vessel is unavailable": "האונייה המשותפת אינה זמינה",
   "ACQUIRING": "מאתר",
@@ -3535,5 +3533,17 @@
     "other": "{count} ספינות טרופות"
   },
   "EMODnet (European waters) · Wikidata (worldwide)": "EMODnet (מימי אירופה) · ויקינתונים (כל העולם)",
-  "European heritage wrecks come from EMODnet Human Activities; notable wrecks worldwide come from Wikidata. Colour shows when the ship sank; marker size grows with deaths. Click a marker for its card.": "ספינות טרופות אירופיות בעלות ערך מורשת מגיעות מ־EMODnet Human Activities; ספינות טרופות בולטות מכל העולם מגיעות מוויקינתונים. הצבע מראה מתי הספינה טבעה; הסמן גדל ככל שמספר ההרוגים עולה. לחץ על סמן כדי לפתוח את הכרטיס שלו."
+  "European heritage wrecks come from EMODnet Human Activities; notable wrecks worldwide come from Wikidata. Colour shows when the ship sank; marker size grows with deaths. Click a marker for its card.": "ספינות טרופות אירופיות בעלות ערך מורשת מגיעות מ־EMODnet Human Activities; ספינות טרופות בולטות מכל העולם מגיעות מוויקינתונים. הצבע מראה מתי הספינה טבעה; הסמן גדל ככל שמספר ההרוגים עולה. לחץ על סמן כדי לפתוח את הכרטיס שלו.",
+  "The shared flight isn't reporting now — showing where it was last seen": "הטיסה המשותפת לא מדווחת עכשיו — מוצג המיקום האחרון הידוע",
+  "The shared flight isn't reporting now — showing where it was at {time}": "הטיסה המשותפת לא מדווחת עכשיו — מוצג המיקום בשעה {time}",
+  "The shared military flight isn't reporting now — showing where it was last seen": "הטיסה הצבאית המשותפת לא מדווחת עכשיו — מוצג המיקום האחרון הידוע",
+  "The shared military flight isn't reporting now — showing where it was at {time}": "הטיסה הצבאית המשותפת לא מדווחת עכשיו — מוצג המיקום בשעה {time}",
+  "The shared vessel isn't reporting now — showing where it was last seen": "כלי השיט המשותף לא מדווח עכשיו — מוצג המיקום האחרון הידוע",
+  "The shared vessel isn't reporting now — showing where it was at {time}": "כלי השיט המשותף לא מדווח עכשיו — מוצג המיקום בשעה {time}",
+  "The shared satellite isn't reporting now — showing where it was last seen": "הלוויין המשותף לא מדווח עכשיו — מוצג המיקום האחרון הידוע",
+  "The shared satellite isn't reporting now — showing where it was at {time}": "הלוויין המשותף לא מדווח עכשיו — מוצג המיקום בשעה {time}",
+  "ICAO: {id}": "ICAO: {id}",
+  "NORAD: {id}": "NORAD: {id}",
+  "MMSI: {id}": "MMSI: {id}",
+  "Vessel UUID: {id}": "UUID של כלי השיט: {id}"
 }

src/i18n/locales/it.json

@@ -2287,8 +2287,6 @@
   "Shared {subject} follow expired": "Il tracciamento condiviso di {subject} è scaduto",
   "Shared {subject} could not be restored — feed unavailable": "Impossibile ripristinare la condivisione di {subject}: feed non disponibile",
   "Shared {subject} is unavailable": "La condivisione di {subject} non è disponibile",
-  "{id} isn't reporting now — showing where it was last seen": "{id} non sta trasmettendo ora: viene mostrata l'ultima posizione nota",
-  "{id} isn't reporting now — showing where it was at {time}": "{id} non sta trasmettendo ora: viene mostrata l'ultima posizione nota ({time})",
   "This share link can't be opened": "Impossibile aprire questo link di condivisione",
   "Shared vessel is unavailable": "La nave condivisa non è disponibile",
   "ACQUIRING": "ACQUISIZIONE",
@@ -3535,5 +3533,17 @@
   "Play speed": "Velocità di riproduzione",
   "Scroll or pinch to zoom, drag to move along · double-click to see it all": "Scorri o pizzica per lo zoom, trascina per spostarti · doppio clic per vedere tutto",
   "1 min/s": "1 min/s",
-  "Photo © {photographer}": "Foto © {photographer}"
+  "Photo © {photographer}": "Foto © {photographer}",
+  "The shared flight isn't reporting now — showing where it was last seen": "Il volo condiviso non sta trasmettendo ora: viene mostrata l'ultima posizione nota",
+  "The shared flight isn't reporting now — showing where it was at {time}": "Il volo condiviso non sta trasmettendo ora: viene mostrata la posizione alle {time}",
+  "The shared military flight isn't reporting now — showing where it was last seen": "Il volo militare condiviso non sta trasmettendo ora: viene mostrata l'ultima posizione nota",
+  "The shared military flight isn't reporting now — showing where it was at {time}": "Il volo militare condiviso non sta trasmettendo ora: viene mostrata la posizione alle {time}",
+  "The shared vessel isn't reporting now — showing where it was last seen": "La nave condivisa non sta trasmettendo ora: viene mostrata l'ultima posizione nota",
+  "The shared vessel isn't reporting now — showing where it was at {time}": "La nave condivisa non sta trasmettendo ora: viene mostrata la posizione alle {time}",
+  "The shared satellite isn't reporting now — showing where it was last seen": "Il satellite condiviso non sta trasmettendo ora: viene mostrata l'ultima posizione nota",
+  "The shared satellite isn't reporting now — showing where it was at {time}": "Il satellite condiviso non sta trasmettendo ora: viene mostrata la posizione alle {time}",
+  "ICAO: {id}": "ICAO: {id}",
+  "NORAD: {id}": "NORAD: {id}",
+  "MMSI: {id}": "MMSI: {id}",
+  "Vessel UUID: {id}": "UUID della nave: {id}"
 }

src/i18n/locales/ja.json

@@ -2209,8 +2209,6 @@
   "Shared {subject} follow expired": "共有された{subject}の追従が期限切れになりました",
   "Shared {subject} could not be restored — feed unavailable": "共有された{subject}を復元できませんでした：フィードを利用できません",
   "Shared {subject} is unavailable": "共有された{subject}は利用できません",
-  "{id} isn't reporting now — showing where it was last seen": "{id}は現在報告していません。最後に確認された位置を表示しています",
-  "{id} isn't reporting now — showing where it was at {time}": "{id}は現在報告していません。{time}時点の位置を表示しています",
   "This share link can't be opened": "この共有リンクは開けません",
   "Shared vessel is unavailable": "共有された船舶は利用できません",
   "ACQUIRING": "取得中",
@@ -3373,5 +3371,17 @@
   "Play speed": "再生速度",
   "Scroll or pinch to zoom, drag to move along · double-click to see it all": "スクロールまたはピンチでズーム、ドラッグで移動 · ダブルクリックで全体表示",
   "1 min/s": "1分/秒",
-  "Photo © {photographer}": "写真 © {photographer}"
+  "Photo © {photographer}": "写真 © {photographer}",
+  "The shared flight isn't reporting now — showing where it was last seen": "共有されたフライトは現在報告していません。最後に確認された位置を表示しています",
+  "The shared flight isn't reporting now — showing where it was at {time}": "共有されたフライトは現在報告していません。{time}時点の位置を表示しています",
+  "The shared military flight isn't reporting now — showing where it was last seen": "共有された軍用機は現在報告していません。最後に確認された位置を表示しています",
+  "The shared military flight isn't reporting now — showing where it was at {time}": "共有された軍用機は現在報告していません。{time}時点の位置を表示しています",
+  "The shared vessel isn't reporting now — showing where it was last seen": "共有された船舶は現在報告していません。最後に確認された位置を表示しています",
+  "The shared vessel isn't reporting now — showing where it was at {time}": "共有された船舶は現在報告していません。{time}時点の位置を表示しています",
+  "The shared satellite isn't reporting now — showing where it was last seen": "共有された衛星は現在報告していません。最後に確認された位置を表示しています",
+  "The shared satellite isn't reporting now — showing where it was at {time}": "共有された衛星は現在報告していません。{time}時点の位置を表示しています",
+  "ICAO: {id}": "ICAO: {id}",
+  "NORAD: {id}": "NORAD: {id}",
+  "MMSI: {id}": "MMSI: {id}",
+  "Vessel UUID: {id}": "船舶UUID: {id}"
 }

src/i18n/locales/pt.json

@@ -2287,8 +2287,6 @@
   "Shared {subject} follow expired": "O acompanhamento compartilhado de {subject} expirou",
   "Shared {subject} could not be restored — feed unavailable": "Não foi possível restaurar o compartilhamento de {subject} — feed indisponível",
   "Shared {subject} is unavailable": "O compartilhamento de {subject} está indisponível",
-  "{id} isn't reporting now — showing where it was last seen": "{id} não está transmitindo agora — mostrando onde foi visto pela última vez",
-  "{id} isn't reporting now — showing where it was at {time}": "{id} não está transmitindo agora — mostrando onde estava em {time}",
   "This share link can't be opened": "Não é possível abrir este link de compartilhamento",
   "Shared vessel is unavailable": "A embarcação compartilhada está indisponível",
   "ACQUIRING": "ADQUIRINDO",
@@ -3535,5 +3533,17 @@
   "Play speed": "Velocidade de reprodução",
   "Scroll or pinch to zoom, drag to move along · double-click to see it all": "Role ou faça pinça para ampliar, arraste para se mover · clique duplo para ver tudo",
   "1 min/s": "1 min/s",
-  "Photo © {photographer}": "Foto © {photographer}"
+  "Photo © {photographer}": "Foto © {photographer}",
+  "The shared flight isn't reporting now — showing where it was last seen": "O voo compartilhado não está transmitindo agora — mostrando a última posição conhecida",
+  "The shared flight isn't reporting now — showing where it was at {time}": "O voo compartilhado não está transmitindo agora — mostrando onde estava às {time}",
+  "The shared military flight isn't reporting now — showing where it was last seen": "O voo militar compartilhado não está transmitindo agora — mostrando a última posição conhecida",
+  "The shared military flight isn't reporting now — showing where it was at {time}": "O voo militar compartilhado não está transmitindo agora — mostrando onde estava às {time}",
+  "The shared vessel isn't reporting now — showing where it was last seen": "A embarcação compartilhada não está transmitindo agora — mostrando a última posição conhecida",
+  "The shared vessel isn't reporting now — showing where it was at {time}": "A embarcação compartilhada não está transmitindo agora — mostrando onde estava às {time}",
+  "The shared satellite isn't reporting now — showing where it was last seen": "O satélite compartilhado não está transmitindo agora — mostrando a última posição conhecida",
+  "The shared satellite isn't reporting now — showing where it was at {time}": "O satélite compartilhado não está transmitindo agora — mostrando onde estava às {time}",
+  "ICAO: {id}": "ICAO: {id}",
+  "NORAD: {id}": "NORAD: {id}",
+  "MMSI: {id}": "MMSI: {id}",
+  "Vessel UUID: {id}": "UUID da embarcação: {id}"
 }

src/i18n/locales/ru.json

@@ -425,8 +425,6 @@
   "Link copied!": "Ссылка скопирована!",
   "Link shared": "Ссылка отправлена",
   "This share link can't be opened": "Не удаётся открыть эту ссылку",
-  "{id} isn't reporting now — showing where it was at {time}": "{id} сейчас не передаёт данные — показано последнее известное место ({time})",
-  "{id} isn't reporting now — showing where it was last seen": "{id} сейчас не передаёт данные — показано последнее известное место",
   "Shared vessel is unavailable": "Судно по ссылке недоступно",
   "Copy failed": "Не удалось скопировать",
   "VISUAL PRESETS": "ПРЕСЕТЫ",
@@ -3616,5 +3614,17 @@
   "Play speed": "Скорость воспроизведения",
   "Scroll or pinch to zoom, drag to move along · double-click to see it all": "Прокрутите или сведите пальцы для масштаба, перетащите для перемещения · двойной щелчок — показать всё",
   "1 min/s": "1 мин/с",
-  "Photo © {photographer}": "Фото © {photographer}"
+  "Photo © {photographer}": "Фото © {photographer}",
+  "The shared flight isn't reporting now — showing where it was last seen": "Общий рейс сейчас не передаёт данные — показано последнее известное место",
+  "The shared flight isn't reporting now — showing where it was at {time}": "Общий рейс сейчас не передаёт данные — показано место в {time}",
+  "The shared military flight isn't reporting now — showing where it was last seen": "Общий военный рейс сейчас не передаёт данные — показано последнее известное место",
+  "The shared military flight isn't reporting now — showing where it was at {time}": "Общий военный рейс сейчас не передаёт данные — показано место в {time}",
+  "The shared vessel isn't reporting now — showing where it was last seen": "Общее судно сейчас не передаёт данные — показано последнее известное место",
+  "The shared vessel isn't reporting now — showing where it was at {time}": "Общее судно сейчас не передаёт данные — показано место в {time}",
+  "The shared satellite isn't reporting now — showing where it was last seen": "Общий спутник сейчас не передаёт данные — показано последнее известное место",
+  "The shared satellite isn't reporting now — showing where it was at {time}": "Общий спутник сейчас не передаёт данные — показано место в {time}",
+  "ICAO: {id}": "ICAO: {id}",
+  "NORAD: {id}": "NORAD: {id}",
+  "MMSI: {id}": "MMSI: {id}",
+  "Vessel UUID: {id}": "UUID судна: {id}"
 }

src/i18n/locales/uk.json

@@ -2325,8 +2325,6 @@
   "Shared {subject} follow expired": "Посилання на стеження застаріло: {subject}",
   "Shared {subject} could not be restored — feed unavailable": "Не вдалося відновити за посиланням: {subject} — потік даних недоступний",
   "Shared {subject} is unavailable": "Недоступно за посиланням: {subject}",
-  "{id} isn't reporting now — showing where it was last seen": "{id} зараз не передає даних — показано останнє відоме місце",
-  "{id} isn't reporting now — showing where it was at {time}": "{id} зараз не передає даних — показано останнє відоме місце ({time})",
   "This share link can't be opened": "Не вдається відкрити це посилання",
   "Shared vessel is unavailable": "Судно за посиланням недоступне",
   "ACQUIRING": "ОТРИМАННЯ",
@@ -3616,5 +3614,17 @@
   "Play speed": "Швидкість відтворення",
   "Scroll or pinch to zoom, drag to move along · double-click to see it all": "Прокрутіть або зведіть пальці для масштабу, перетягніть для переміщення · подвійне клацання — показати все",
   "1 min/s": "1 хв/с",
-  "Photo © {photographer}": "Фото © {photographer}"
+  "Photo © {photographer}": "Фото © {photographer}",
+  "The shared flight isn't reporting now — showing where it was last seen": "Спільний рейс зараз не передає даних — показано останнє відоме місце",
+  "The shared flight isn't reporting now — showing where it was at {time}": "Спільний рейс зараз не передає даних — показано місце о {time}",
+  "The shared military flight isn't reporting now — showing where it was last seen": "Спільний військовий рейс зараз не передає даних — показано останнє відоме місце",
+  "The shared military flight isn't reporting now — showing where it was at {time}": "Спільний військовий рейс зараз не передає даних — показано місце о {time}",
+  "The shared vessel isn't reporting now — showing where it was last seen": "Спільне судно зараз не передає даних — показано останнє відоме місце",
+  "The shared vessel isn't reporting now — showing where it was at {time}": "Спільне судно зараз не передає даних — показано місце о {time}",
+  "The shared satellite isn't reporting now — showing where it was last seen": "Спільний супутник зараз не передає даних — показано останнє відоме місце",
+  "The shared satellite isn't reporting now — showing where it was at {time}": "Спільний супутник зараз не передає даних — показано місце о {time}",
+  "ICAO: {id}": "ICAO: {id}",
+  "NORAD: {id}": "NORAD: {id}",
+  "MMSI: {id}": "MMSI: {id}",
+  "Vessel UUID: {id}": "UUID судна: {id}"
 }

src/i18n/locales/zh-CN.json

@@ -1605,8 +1605,6 @@
   "Link copied!": "链接已复制！",
   "Link shared": "链接已分享",
   "This share link can't be opened": "无法打开此分享链接",
-  "{id} isn't reporting now — showing where it was at {time}": "{id} 目前没有发送信号——显示其在 {time} 的位置",
-  "{id} isn't reporting now — showing where it was last seen": "{id} 目前没有发送信号——显示其最后出现的位置",
   "Shared vessel is unavailable": "分享的船只不可用",
   "Copy failed": "复制失败",
   "Return map to straight-down view": "将地图恢复为垂直俯视",
@@ -3373,5 +3371,17 @@
   "Play speed": "播放速度",
   "Scroll or pinch to zoom, drag to move along · double-click to see it all": "滚动或双指缩放，拖动以移动 · 双击查看全部",
   "1 min/s": "1 分钟/秒",
-  "Photo © {photographer}": "照片 © {photographer}"
+  "Photo © {photographer}": "照片 © {photographer}",
+  "The shared flight isn't reporting now — showing where it was last seen": "共享的航班目前没有发送信号——显示其最后出现的位置",
+  "The shared flight isn't reporting now — showing where it was at {time}": "共享的航班目前没有发送信号——显示其在 {time} 的位置",
+  "The shared military flight isn't reporting now — showing where it was last seen": "共享的军用航班目前没有发送信号——显示其最后出现的位置",
+  "The shared military flight isn't reporting now — showing where it was at {time}": "共享的军用航班目前没有发送信号——显示其在 {time} 的位置",
+  "The shared vessel isn't reporting now — showing where it was last seen": "共享的船舶目前没有发送信号——显示其最后出现的位置",
+  "The shared vessel isn't reporting now — showing where it was at {time}": "共享的船舶目前没有发送信号——显示其在 {time} 的位置",
+  "The shared satellite isn't reporting now — showing where it was last seen": "共享的卫星目前没有发送信号——显示其最后出现的位置",
+  "The shared satellite isn't reporting now — showing where it was at {time}": "共享的卫星目前没有发送信号——显示其在 {time} 的位置",
+  "ICAO: {id}": "ICAO：{id}",
+  "NORAD: {id}": "NORAD：{id}",
+  "MMSI: {id}": "MMSI：{id}",
+  "Vessel UUID: {id}": "船舶 UUID：{id}"
 }

src/i18n/locales/zh-Hant.json

@@ -2983,8 +2983,6 @@
   "Take the exit {direction}": "從出口{direction}駛出",
   "Link shared": "鏈接已分享",
   "This share link can't be opened": "無法打開此分享鏈接",
-  "{id} isn't reporting now — showing where it was at {time}": "{id} 目前沒有發送信號——顯示其在 {time} 的位置",
-  "{id} isn't reporting now — showing where it was last seen": "{id} 目前沒有發送信號——顯示其最後出現的位置",
   "Shared vessel is unavailable": "分享的船隻不可用",
   "Check the spelling and press Enter to search again.": "請檢查拼寫，然後按 Enter 重新搜索。",
   "Press Enter to try again.": "按 Enter 重試。",
@@ -3373,5 +3371,17 @@
   "Play speed": "播放速度",
   "Scroll or pinch to zoom, drag to move along · double-click to see it all": "捲動或雙指縮放，拖曳以移動 · 按兩下查看全部",
   "1 min/s": "1 分鐘/秒",
-  "Photo © {photographer}": "照片 © {photographer}"
+  "Photo © {photographer}": "照片 © {photographer}",
+  "The shared flight isn't reporting now — showing where it was last seen": "共享的航班目前沒有發送信號——顯示其最後出現的位置",
+  "The shared flight isn't reporting now — showing where it was at {time}": "共享的航班目前沒有發送信號——顯示其在 {time} 的位置",
+  "The shared military flight isn't reporting now — showing where it was last seen": "共享的軍用航班目前沒有發送信號——顯示其最後出現的位置",
+  "The shared military flight isn't reporting now — showing where it was at {time}": "共享的軍用航班目前沒有發送信號——顯示其在 {time} 的位置",
+  "The shared vessel isn't reporting now — showing where it was last seen": "共享的船舶目前沒有發送信號——顯示其最後出現的位置",
+  "The shared vessel isn't reporting now — showing where it was at {time}": "共享的船舶目前沒有發送信號——顯示其在 {time} 的位置",
+  "The shared satellite isn't reporting now — showing where it was last seen": "共享的衛星目前沒有發送信號——顯示其最後出現的位置",
+  "The shared satellite isn't reporting now — showing where it was at {time}": "共享的衛星目前沒有發送信號——顯示其在 {time} 的位置",
+  "ICAO: {id}": "ICAO：{id}",
+  "NORAD: {id}": "NORAD：{id}",
+  "MMSI: {id}": "MMSI：{id}",
+  "Vessel UUID: {id}": "船舶 UUID：{id}"
 }

src/i18n/same-as-english.json

@@ -44,7 +44,10 @@
     "{direction} {angle}°",
     "{direction} · {elevation}",
     "{source} HTTP {status}",
-    "▲ {frp} MW"
+    "▲ {frp} MW",
+    "ICAO: {id}",
+    "MMSI: {id}",
+    "NORAD: {id}"
   ],
   "de": [
     "1090 MHz",
@@ -238,7 +241,10 @@
     "ΔN",
     "Ⅱ PAUSE",
     "≥ {value} MW",
-    "▲ {frp} MW"
+    "▲ {frp} MW",
+    "ICAO: {id}",
+    "MMSI: {id}",
+    "NORAD: {id}"
   ],
   "es": [
     "1 min/s",
@@ -395,7 +401,10 @@
     "Reptiles",
     "acartia.io ↗",
     "iNaturalist ↗",
-    "iNaturalist"
+    "iNaturalist",
+    "ICAO: {id}",
+    "MMSI: {id}",
+    "NORAD: {id}"
   ],
   "fr": [
     "1 min/s",
@@ -810,7 +819,10 @@
     "acartia.io ↗",
     "iNaturalist ↗",
     "iNaturalist",
-    "SATELLITE"
+    "SATELLITE",
+    "ICAO: {id}",
+    "MMSI: {id}",
+    "NORAD: {id}"
   ],
   "ja": [
     "1090 MHz",
@@ -873,7 +885,10 @@
     "ΔE",
     "ΔN",
     "≥ {value} MW",
-    "▲ {frp} MW"
+    "▲ {frp} MW",
+    "ICAO: {id}",
+    "MMSI: {id}",
+    "NORAD: {id}"
   ],
   "pt": [
     "1 min/s",
@@ -1031,7 +1046,10 @@
     "CC BY 4.0",
     "acartia.io ↗",
     "iNaturalist ↗",
-    "iNaturalist"
+    "iNaturalist",
+    "ICAO: {id}",
+    "MMSI: {id}",
+    "NORAD: {id}"
   ],
   "ru": [
     "1900–1945",
@@ -1064,7 +1082,10 @@
     "iNaturalist ↗",
     "{direction} · {elevation}",
     "{direction} {angle}°",
-    "{division}, {country}"
+    "{division}, {country}",
+    "ICAO: {id}",
+    "MMSI: {id}",
+    "NORAD: {id}"
   ],
   "uk": [
     "1900–1945",
@@ -1092,7 +1113,10 @@
     "iNaturalist ↗",
     "{direction} · {elevation}",
     "{direction} {angle}°",
-    "{division}, {country}"
+    "{division}, {country}",
+    "ICAO: {id}",
+    "MMSI: {id}",
+    "NORAD: {id}"
   ],
   "zh-CN": [
     "1090 MHz",
@@ -1331,6 +1355,9 @@
     "TLE",
     "{value} KM",
     "{value} KM/S",
-    "Ironbow"
+    "Ironbow",
+    "ICAO: {id}",
+    "MMSI: {id}",
+    "NORAD: {id}"
   ]
 }

src/layers/awareness/history.js

@@ -150,7 +150,7 @@ export function createHistory({ state: layerState, services, parts, source }) {
     return (
       items.find(
         (item) =>
-          String(item?.icao24 || item?.mmsi || item?.id) === String(subject.id),
+          String(item?.icao24 || item?.id || item?.mmsi) === String(subject.id),
       ) || subject
     );
   }

src/layers/awareness/panel.js

@@ -117,7 +117,7 @@ export function createPanel({ state: layerState, parts }) {
       .slice(page, page + AWARENESS_PAGE_SIZE)
       .map((item, index) => {
         const label = formatAwarenessLabel(item);
-        const targetId = item.icao24 || item.mmsi || item.id;
+        const targetId = item.icao24 || item.id || item.mmsi;
         const distance = presentAwarenessDistance(item.distanceM);
         if (!targetId)
           return {

src/layers/awareness/subject.js

@@ -85,7 +85,7 @@ export function createSubject({ state: layerState, services, parts, source }) {
       .getNearby(position, AWARENESS_RADIUS_M, AWARENESS_QUERY_LIMIT)
       .filter(
         (item) =>
-          !parts.queries.isSame(subject, item, 'ais-live-vessels', 'mmsi'),
+          !parts.queries.isSame(subject, item, 'ais-live-vessels', 'id'),
       );
     const coverage = installationsState.stats?.coverage;
     const installationRadius =
@@ -519,7 +519,7 @@ export function createSubject({ state: layerState, services, parts, source }) {
     if (!Number.isFinite(latitude) || !Number.isFinite(longitude)) return null;
     return {
       layerId: record.layerId,
-      id: record.properties?.mmsi || record.id,
+      id: record.properties?.vesselId || record.id,
       label: record.label || record.id,
       memberNames: record.properties?.memberNames || [],
       position: Cesium.Cartesian3.fromDegrees(longitude, latitude, 0),

src/layers/vessels/cards.js

@@ -60,7 +60,7 @@ export function createCards({
       parts.push(`${roundHeadingDegrees(direction)}°`);
     return {
       id: vesselOverlayEntryId(record),
-      actionable: Boolean(record?.mmsi),
+      actionable: Boolean(record?.id),
       position:
         components.rendering.getVisual(record).billboard?.position ||
         components.rendering.getVisual(record).position,
@@ -101,7 +101,7 @@ export function createCards({
     );
     return {
       id: vesselOverlayEntryId(record),
-      actionable: Boolean(record?.mmsi),
+      actionable: Boolean(record?.id),
       position:
         components.rendering.getVisual(record).billboard?.position ||
         components.rendering.getVisual(record).position,
@@ -114,11 +114,11 @@ export function createCards({
     };
   }
 
-  /** Stable overlay identity for MMSI-keyed and source-retained unkeyed rows. */
+  /** Stable overlay identity for keyed and source-retained unkeyed rows. */
 
   function vesselOverlayEntryId(record) {
-    const mmsi = String(record?.mmsi || '').trim();
-    if (mmsi) return `vessel:${mmsi}`;
+    const id = String(record?.id || '').trim();
+    if (id) return `vessel:${id}`;
     const name = String(record?.name || 'VESSEL').trim() || 'VESSEL';
     const lat = Number.isFinite(record?.lat) ? record.lat.toFixed(5) : 'x';
     const lon = Number.isFinite(record?.lon) ? record.lon.toFixed(5) : 'x';
@@ -161,7 +161,9 @@ export function createCards({
 
   function displayVesselName(record) {
     const name = String(record.name || '').trim();
-    if (name && name !== 'VESSEL' && name !== record.mmsi) return name;
+    // A source may name a vessel by its id when it has no name.
+    if (name && name !== 'VESSEL' && name !== record.mmsi && name !== record.id)
+      return name;
     return record.mmsi ? `MMSI ${record.mmsi}` : t('VESSEL');
   }
 

src/layers/vessels/clockFollow.test.mjs

@@ -37,19 +37,19 @@ function store() {
 test('rows at another time stand in for every vessel, selected or not', () => {
   const probe = store();
   probe.reconcile([row('111'), row('222')]);
-  const selectedRecord = probe.records.byMmsi.get('222');
+  const selectedRecord = probe.records.byId.get('222');
   probe.reconcile([row('111', { last_position_epoch: 900 })], {
     complete: false,
     selectedRecord,
     replace: true,
   });
-  assert.deepEqual([...probe.records.byMmsi.keys()], ['111']);
+  assert.deepEqual([...probe.records.byId.keys()], ['111']);
   assert.deepEqual(probe.events.slice(-3), [
     ['update', '111'],
     ['remove', '222', true],
     ['removed', '222'],
   ]);
-  assert.equal(probe.records.byMmsi.get('111').motion, null);
+  assert.equal(probe.records.byId.get('111').motion, null);
 });
 
 test('following the clock, a vessel keeps where its fix moved from', () => {
@@ -58,7 +58,7 @@ test('following the clock, a vessel keeps where its fix moved from', () => {
   probe.reconcile([row('111', { lat: 52, last_position_epoch: 1_010 })], {
     follow: true,
   });
-  const record = probe.records.byMmsi.get('111');
+  const record = probe.records.byId.get('111');
   assert.deepEqual(record.motion, {
     fromLat: 51.93,
     fromLon: 4.05,
@@ -75,7 +75,7 @@ test('following the clock, a vessel keeps where its fix moved from', () => {
   live.reconcile([row('111')]);
   live.reconcile([row('111', { lat: 52, last_position_epoch: 1_010 })]);
   assert.equal(
-    Object.hasOwn(live.records.byMmsi.get('111'), 'motion'),
+    Object.hasOwn(live.records.byId.get('111'), 'motion'),
     false,
     'live records are as before',
   );

src/layers/vessels/cockpitSubject.js

@@ -99,7 +99,7 @@ function finiteOrNull(value) {
  * @returns {object|null} Subject info, or null without a usable fix.
  */
 export function vesselCockpitInfo(record) {
-  if (!record?.mmsi) return null;
+  if (!record?.id) return null;
   const latitude = Number(record.lat);
   const longitude = Number(record.lon);
   if (!Number.isFinite(latitude) || !Number.isFinite(longitude)) return null;
@@ -111,9 +111,9 @@ export function vesselCockpitInfo(record) {
   return {
     kind: 'vessel',
     layerId: VESSEL_COCKPIT_LAYER_ID,
-    id: String(record.mmsi),
-    mmsi: String(record.mmsi),
-    name: String(record.name || record.mmsi),
+    id: String(record.id),
+    mmsi: String(record.mmsi || ''),
+    name: String(record.name || record.mmsi || record.id),
     type: String(record.type || ''),
     typeLabel: displayVesselType(record.type),
     destination: String(record.destination || '').trim(),

src/layers/vessels/cockpitSubject.test.mjs

@@ -43,6 +43,7 @@ test('an unknown or missing type has no eye height of its own', () => {
 
 test('vessel info faces the true heading and moves along course over ground', () => {
   const info = vesselCockpitInfo({
+    id: '211000000',
     mmsi: '211000000',
     name: 'NORDIC STAR',
     type: '70',
@@ -58,6 +59,7 @@ test('vessel info faces the true heading and moves along course over ground', ()
   assert.equal(info.kind, 'vessel');
   assert.equal(info.layerId, VESSEL_COCKPIT_LAYER_ID);
   assert.equal(info.id, '211000000');
+  assert.equal(info.mmsi, '211000000');
   assert.equal(info.typeLabel, 'CARGO');
   assert.equal(info.track, 90);
   assert.equal(info.motionCourse, 95);
@@ -70,7 +72,7 @@ test('vessel info faces the true heading and moves along course over ground', ()
 });
 
 test('a missing heading or course falls back to the other', () => {
-  const base = { mmsi: '1', lat: 1, lon: 1, speed: 3 };
+  const base = { id: '1', mmsi: '1', lat: 1, lon: 1, speed: 3 };
   assert.equal(vesselCockpitInfo({ ...base, course: 40 }).track, 40);
   assert.equal(vesselCockpitInfo({ ...base, heading: 50 }).motionCourse, 50);
   const neither = vesselCockpitInfo(base);
@@ -79,7 +81,7 @@ test('a missing heading or course falls back to the other', () => {
 });
 
 test('the subject says whether its track is the heading or the course', () => {
-  const base = { mmsi: '1', lat: 1, lon: 1, speed: 3 };
+  const base = { id: '1', mmsi: '1', lat: 1, lon: 1, speed: 3 };
   assert.equal(
     vesselCockpitInfo({ ...base, heading: 50, course: 40 }).trackSource,
     'heading',
@@ -99,11 +101,12 @@ test('the subject says whether its track is the heading or the course', () => {
 test('a vessel without identity or position is not a subject', () => {
   assert.equal(vesselCockpitInfo(null), null);
   assert.equal(vesselCockpitInfo({ lat: 1, lon: 1 }), null);
-  assert.equal(vesselCockpitInfo({ mmsi: '1', lat: 'x', lon: 1 }), null);
+  assert.equal(vesselCockpitInfo({ id: '1', mmsi: '1', lat: 'x', lon: 1 }), null);
 });
 
 test('a vessel missing from recent refreshes reads as stale', () => {
   const info = vesselCockpitInfo({
+    id: '1',
     mmsi: '1',
     lat: 1,
     lon: 1,
@@ -111,3 +114,20 @@ test('a vessel missing from recent refreshes reads as stale', () => {
   });
   assert.equal(info.stale, true);
 });
+
+test('a vessel is the subject by its id; an MMSI is only shown when known', () => {
+  const info = vesselCockpitInfo({
+    id: 'b6a7c1e2-provider-id',
+    mmsi: '',
+    name: 'NORDIC STAR',
+    lat: 54.5,
+    lon: 10.2,
+  });
+  assert.equal(info.id, 'b6a7c1e2-provider-id');
+  assert.equal(info.mmsi, '');
+  assert.equal(
+    vesselCockpitInfo({ mmsi: '211000000', lat: 54.5, lon: 10.2 }),
+    null,
+    'a record with no id is unkeyed and cannot be ridden',
+  );
+});

src/layers/vessels/evidence.js

@@ -47,7 +47,7 @@ export function createEvidence({
           )
         : null;
       return {
-        id: record.mmsi,
+        id: record.id,
         show: bb?.show === true,
         alpha: bb?.color?.alpha ?? null,
         x: screen?.x ?? null,

src/layers/vessels/ingestion.js

@@ -201,9 +201,11 @@ export function createIngestion({
     return { reconciled: true, ...snapshot };
   }
 
+  /** The layer's row for a source record: keyed by its id, MMSI shown when known. */
   function vesselDisplayRow(record) {
     return {
-      mmsi: record.id,
+      id: record.id,
+      mmsi: String(record.mmsi ?? '').trim(),
       reference: record.reference,
       lat: record.latitude,
       lon: record.longitude,

src/layers/vessels/lifecycle.js

@@ -116,7 +116,7 @@ export function createLifecycle({
     state.feed.abort = null;
     state.billboardCollection = null;
     state.records.all = [];
-    state.records.byMmsi = new Map();
+    state.records.byId = new Map();
     state.records.unkeyed = [];
     state.clickHandler = null;
     state.keyTarget = null;
@@ -133,7 +133,7 @@ export function createLifecycle({
     state.selectedRecord = null;
     state.trail = null;
     state.trailPositions = [];
-    state.trailMmsi = null;
+    state.trailId = null;
     state.trailBackfillToken = 0;
   }
   const methods = {
@@ -188,9 +188,9 @@ export function createLifecycle({
           });
       }
       // Pick-ownership (H2): vessel picks carry the record OBJECT as their id;
-      // the registry resolver reduces it to the record's mmsi (a string key).
+      // the registry resolver reduces it to the record's id (a string key).
       registerPickOwner('ais-live-vessels', (pickedId) =>
-        state.records.byMmsi.has(pickedId),
+        state.records.byId.has(pickedId),
       );
       restoreSpriteOrderOnEnable('ais', activeViewer);
       // Vessels are asked for by view, so ask again when the view moves away.

src/layers/vessels/ownership.test.mjs

@@ -98,7 +98,7 @@ test('vessel construction is inert and each instance owns its records, icon cach
   const two = createVesselState({ source, services: services() });
   for (const key of ['state', 'shipIconCache', '_scratchFocusScreen'])
     assert.notEqual(one[key], two[key]);
-  assert.notEqual(one.state.records.byMmsi, two.state.records.byMmsi);
+  assert.notEqual(one.state.records.byId, two.state.records.byId);
   assert.notEqual(one.state.feed, two.state.feed);
   assert.notEqual(one.state.records.all, two.state.records.all);
   assert.notEqual(one.state.records.unkeyed, two.state.records.unkeyed);
@@ -272,7 +272,7 @@ test('partial-feed expiry releases a selected vessel and its pending trail', asy
   layer.selectById('222');
   current = snapshot([observation('111')], { complete: false });
   await layer.update();
-  assert.equal(layer.getSelectedInfo().mmsi, '222');
+  assert.equal(layer.getSelectedInfo().id, '222');
   assert.equal(signal.aborted, false);
   advance(5 * 60 * 1000);
   await layer.update();
@@ -421,3 +421,97 @@ test('vessel stats name the provider the last snapshot reported', async () => {
   await layer.update();
   assert.equal(layer.getStats().source, 'Datalastic');
 });
+
+test('two vessels sharing an MMSI under different ids stay two vessels', async () => {
+  const shared = (id, longitude) => ({
+    ...observation(id),
+    mmsi: '123456789',
+    longitude,
+    name: `HULL ${id}`,
+  });
+  const { layer, primitives } = setup({
+    getSnapshot: async () =>
+      snapshot([shared('hull-a', 4.05), shared('hull-b', 4.25)]),
+  });
+  await layer.update();
+  assert.equal(layer.getStats().count, 2);
+  assert.equal(primitives.size, 2);
+  assert.equal(layer.hasContact('hull-a'), true);
+  assert.equal(layer.hasContact('hull-b'), true);
+  // An MMSI is not a key, but a link naming one still finds a vessel with it.
+  assert.equal(layer.hasContact('123456789'), true);
+  assert.equal(layer.hasContact('987654321'), false);
+  assert.deepEqual(
+    layer
+      .getAllPositions()
+      .map(({ id }) => id)
+      .sort(),
+    ['hull-a', 'hull-b'],
+  );
+  assert.equal(layer.selectById('hull-b'), true);
+  assert.deepEqual(
+    [layer.getSelectedInfo().id, layer.getSelectedInfo().mmsi],
+    ['hull-b', '123456789'],
+  );
+  assert.equal(
+    layer.selectById('123456789'),
+    true,
+    'a link naming the MMSI selects a vessel with it',
+  );
+  assert.equal(layer.getSelectedInfo().mmsi, '123456789');
+  assert.equal(layer.selectById('hull-b'), true);
+  // A lookup by the shared MMSI still finds a vessel that has it.
+  assert.equal(layer.findByQuery('123456789').mmsi, '123456789');
+});
+
+test('a vessel with an id and no MMSI renders and can be selected', async () => {
+  const { layer, primitives } = setup({
+    getSnapshot: async () =>
+      snapshot([{ ...observation('7f3c9a10-provider-id'), name: 'NO MMSI' }]),
+  });
+  await layer.update();
+  assert.equal(primitives.size, 1);
+  const [primitive] = primitives;
+  assert.equal(primitive.id.id, '7f3c9a10-provider-id');
+  assert.equal(primitive.id.mmsi, '');
+  assert.equal(layer.selectById('7f3c9a10-provider-id'), true);
+  const info = layer.getSelectedInfo();
+  assert.equal(info.id, '7f3c9a10-provider-id');
+  assert.equal(info.mmsi, '');
+  assert.equal(layer.getCockpitSubject().id, '7f3c9a10-provider-id');
+  assert.equal(layer.testing._getVesselStateForTest().trailId, info.id);
+});
+
+test('a vessel keyed by a UUID is found in any case and names its drawn fix', async () => {
+  const uuid = '0770e3ca-b896-c307-f499-4f9df2b8f86b';
+  const { layer } = setup({
+    getSnapshot: async () =>
+      snapshot([{ ...observation(uuid.toUpperCase()), name: 'UUID HULL' }]),
+  });
+  await layer.update();
+  assert.equal(layer.getSelectedFix(), null, 'nothing selected');
+  // A share link carries the UUID in lowercase.
+  assert.equal(layer.hasContact(uuid), true);
+  assert.equal(layer.selectById(uuid), true);
+  const fix = layer.getSelectedFix();
+  assert.equal(fix.id, uuid.toUpperCase());
+  assert.ok(fix.position, 'where the vessel is drawn');
+  assert.equal(fix.observedAtMs, 500);
+  assert.equal(layer.hasContact('0770e3ca-b896-c307-f499-4f9df2b8f86c'), false);
+});
+
+test('AIS feed rows stay keyed by their MMSI', async () => {
+  const { vesselSnapshot } = await import('../../sources/live/vessels.js');
+  const row = { mmsi: '235000001', lat: 51.93, lon: 4.05, name: 'TERN' };
+  const { layer } = setup({
+    getSnapshot: async () =>
+      vesselSnapshot({ rows: [row, { ...row, lon: 4.2 }], status: 'live' }),
+  });
+  await layer.update();
+  assert.equal(layer.getStats().count, 1, 'one MMSI is one vessel on AIS');
+  assert.equal(layer.selectById('235000001'), true);
+  assert.deepEqual(
+    [layer.getSelectedInfo().id, layer.getSelectedInfo().mmsi],
+    ['235000001', '235000001'],
+  );
+});

src/layers/vessels/queries.js

@@ -28,6 +28,9 @@ import {
 } from './policy.js';
 import { VESSEL_OVERLAY_SOURCE_ID } from '../../data/vesselLabels.js';
 
+const UUID_KEY =
+  /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/i;
+
 export function createQueries({
   vesselState,
   services,
@@ -38,6 +41,28 @@ export function createQueries({
   const { state } = vesselState;
   const { formatKnots } = services.labels;
 
+  /**
+   * The vessel keyed `id`, else the first whose MMSI is `id`: a link or a
+   * caller that names a vessel by its MMSI still finds it. A share link
+   * carries a UUID key in lowercase, so a UUID matches in any case.
+   * @param {string} id
+   * @returns {object|null}
+   */
+  function recordFor(id) {
+    const record = state.records.byId?.get(id);
+    if (record) return record;
+    if (UUID_KEY.test(id)) {
+      const wanted = id.toLowerCase();
+      for (const candidate of state.records.byId?.values() ?? [])
+        if (candidate.id.toLowerCase() === wanted) return candidate;
+      return null;
+    }
+    if (!/^\d{1,10}$/.test(id)) return null;
+    for (const candidate of state.records.byId?.values() ?? [])
+      if (candidate.mmsi === id) return candidate;
+    return null;
+  }
+
   /**
    * Seconds until the server's next reconnect attempt, or 0 when none is
    * scheduled. Mirrors the flights layer's `retryInSec` chip affordance.
@@ -175,8 +200,9 @@ export function createQueries({
    * fields are null, never NaN/undefined. navStatus is always null: the
    * /api/vessels proxy does not surface AIS NavigationalStatus, so it
    * cannot be derived client-side.
-   * @param {Object|null|undefined} record - `state.records.byMmsi`/`state.records.all` entry.
-   * @returns {{id: string|null, mmsi: string|null, name: string|null,
+   * @param {Object|null|undefined} record - `state.records.byId`/`state.records.all` entry.
+   * @returns {{id: string|null, vesselId: string|null, mmsi: string|null,
+   *   name: string|null,
    *   lat: number|null, lon: number|null, speedKts: number|null,
    *   courseDeg: number|null, shipType: string|null, destination: string|null,
    *   navStatus: null}}
@@ -188,10 +214,14 @@ export function createQueries({
       const t = String(v ?? '').trim();
       return t || null;
     };
+    const vesselId = text(record?.id);
     const mmsi = text(record?.mmsi);
     const name = text(record?.name);
     return {
-      id: name || mmsi,
+      // A display label, as every layer's analyst `id` is; `vesselId` is the
+      // key and `mmsi` the vessel's MMSI when known.
+      id: name || mmsi || vesselId,
+      vesselId,
       mmsi,
       name,
       lat: num(record?.lat),
@@ -225,32 +255,32 @@ export function createQueries({
    * trail picks as no-ops. The interaction wire also reserves sibling-owned
    * picks before this reducer so their camera action cannot mutate AIS state.
    *
-   * @param {{selectedMmsi?: string|number|null, pickedMmsi?: string|number|null,
+   * @param {{selectedId?: string|number|null, pickedId?: string|number|null,
    *   gesture?: 'click'|'escape'}} input - Current selection plus owned pick.
    * @returns {{action: 'none'|'select'|'deselect'}}
    */
 
   function reduceVesselSelection(input = {}) {
-    const selectedMmsi = normalizeSelectionMmsi(input.selectedMmsi);
-    const pickedMmsi = normalizeSelectionMmsi(input.pickedMmsi);
+    const selectedId = normalizeSelectionId(input.selectedId);
+    const pickedId = normalizeSelectionId(input.pickedId);
     const gesture = input.gesture || 'click';
 
     if (gesture === 'escape') {
-      return selectedMmsi ? { action: 'deselect' } : { action: 'none' };
+      return selectedId ? { action: 'deselect' } : { action: 'none' };
     }
     if (gesture !== 'click') {
       return { action: 'none' };
     }
-    if (pickedMmsi) {
-      if (pickedMmsi === selectedMmsi) {
+    if (pickedId) {
+      if (pickedId === selectedId) {
         return { action: 'none' };
       }
       return { action: 'select' };
     }
-    return selectedMmsi ? { action: 'deselect' } : { action: 'none' };
+    return selectedId ? { action: 'deselect' } : { action: 'none' };
   }
 
-  function normalizeSelectionMmsi(value) {
+  function normalizeSelectionId(value) {
     if (value === null || value === undefined) return null;
     const text = String(value).trim();
     return text || null;
@@ -275,9 +305,10 @@ export function createQueries({
     statsRefreshInterval: 1000,
 
     /**
-     * Find a vessel by exact MMSI or case-insensitive name substring.
-     * @param {string|number} query MMSI or partial vessel name.
-     * @returns {{ mmsi: string, name: string, position: Cesium.Cartesian3, latitude: number, longitude: number, speedKt: number|null, course: number|null, type: string }|null}
+     * Find a vessel by its exact id, exact MMSI or case-insensitive name
+     * substring. Vessels can share an MMSI; the first that has it is found.
+     * @param {string|number} query Vessel id, MMSI or partial vessel name.
+     * @returns {{ id: string, mmsi: string, name: string, position: Cesium.Cartesian3, latitude: number, longitude: number, speedKt: number|null, course: number|null, type: string }|null}
      */
     findByQuery(query) {
       if (query === null || query === undefined) return null;
@@ -286,9 +317,9 @@ export function createQueries({
       const q = String(query).trim();
       if (!q) return null;
 
-      let record = null;
-      if (/^\d+$/.test(q)) {
-        record = state.records.byMmsi.get(q) || null;
+      let record = state.records.byId.get(q) || null;
+      if (!record && /^\d+$/.test(q)) {
+        record = records.find((r) => r.mmsi === q) || null;
       }
       if (!record) {
         const lower = q.toLowerCase();
@@ -306,6 +337,7 @@ export function createQueries({
         components.rendering.getVisual(record).position;
       if (!position) return null;
       return {
+        id: record.id,
         mmsi: record.mmsi,
         name: record.name,
         position,
@@ -322,7 +354,7 @@ export function createQueries({
      * @param {Cesium.Cartesian3} centerCartesian Center of the search.
      * @param {number} rangeM Max distance in meters (non-finite = unbounded).
      * @param {number} [maxCount=25] Maximum entries to return.
-     * @returns {Array<{ mmsi: string, name: string, position: Cesium.Cartesian3, distanceM: number }>}
+     * @returns {Array<{ id: string, mmsi: string, name: string, position: Cesium.Cartesian3, distanceM: number }>}
      */
     getNearby(centerCartesian, rangeM, maxCount = 25) {
       const records = state.records.all;
@@ -342,6 +374,7 @@ export function createQueries({
         const distanceM = Cesium.Cartesian3.distance(centerCartesian, position);
         if (!Number.isFinite(distanceM) || distanceM > range) continue;
         entries.push({
+          id: record.id,
           mmsi: record.mmsi,
           name: record.name,
           position,
@@ -363,7 +396,7 @@ export function createQueries({
      * @returns {Array<{ id: string, name: string, latitude: number,
      *   longitude: number, course: number|null, heading: number|null,
      *   type: string, color: string, stale: boolean }>} Empty while the
-     *   layer is off. A ship with no MMSI has an `unkeyed:` id.
+     *   layer is off. A ship with no id has an `unkeyed:` id.
      */
     getRadarContacts(lat, lon, rangeM, maxCount = 60) {
       const records = state.records.all;
@@ -373,7 +406,7 @@ export function createQueries({
       const cap =
         Number.isFinite(maxCount) && maxCount > 0 ? Math.floor(maxCount) : 60;
       const center = { lat, lon };
-      const subject = state.cockpitSubjectMmsi;
+      const subject = state.cockpitSubjectId;
       const finite = (value) => {
         if (value === null || value === undefined || value === '') return null;
         const number = Number(value);
@@ -382,7 +415,7 @@ export function createQueries({
 
       const entries = [];
       records.forEach((record, index) => {
-        if (subject && String(record.mmsi) === subject) return;
+        if (subject && String(record.id) === subject) return;
         const distanceM = greatCircleMeters(center, {
           lat: record.lat,
           lon: record.lon,
@@ -392,8 +425,8 @@ export function createQueries({
       });
       entries.sort((a, b) => a.distanceM - b.distanceM);
       return entries.slice(0, cap).map(({ record, index }) => ({
-        // A ship with no MMSI still needs a key of its own on the scope.
-        id: record.mmsi ? String(record.mmsi) : `unkeyed:${index}`,
+        // A ship with no id still needs a key of its own on the scope.
+        id: record.id ? String(record.id) : `unkeyed:${index}`,
         name: String(record.name || record.mmsi || ''),
         latitude: record.lat,
         longitude: record.lon,
@@ -414,22 +447,22 @@ export function createQueries({
      * Whether this layer still carries a vessel, in O(1).
      *
      * Mirror of `flights.hasContact`: presence consumers must not infer absence
-     * from the capped `getAllPositions` rows. `vesselMap` is MMSI-keyed.
+     * from the capped `getAllPositions` rows. Records are keyed by id.
      * A disabled layer keeps its records, so it must decline rather than answer
      * from data the user can no longer see.
-     * @param {string} mmsi Vessel identifier.
+     * @param {string} id Vessel id.
      * @returns {boolean|null} Presence, or null when the layer is disabled or
      *   holds no data and therefore cannot answer.
      */
-    hasContact(mmsi) {
+    hasContact(id) {
       if (
         !state.feed.enabled ||
-        !state.records.byMmsi ||
-        state.records.byMmsi.size === 0
+        !state.records.byId ||
+        state.records.byId.size === 0
       )
         return null;
-      if (!mmsi) return false;
-      return state.records.byMmsi.has(String(mmsi).trim());
+      if (!id) return false;
+      return Boolean(recordFor(String(id).trim()));
     },
 
     getAllPositions(maxCount = 800) {
@@ -445,8 +478,8 @@ export function createQueries({
         const position = visual.billboard?.position || visual.position;
         if (!position) continue;
         result.push({
-          id: record.mmsi,
-          label: record.name || record.mmsi,
+          id: record.id,
+          label: record.name || record.mmsi || record.id,
           position,
           latitude: record.lat,
           longitude: record.lon,
@@ -479,16 +512,16 @@ export function createQueries({
     },
 
     /**
-     * Select a vessel by MMSI via the same path as a map click
-     * (highlight + HUD update).
-     * @param {string|number} mmsi Vessel MMSI.
+     * Select a vessel by id via the same path as a map click
+     * (highlight + HUD update). An AIS feed's vessels are keyed by MMSI.
+     * @param {string|number} id Vessel id.
      * @returns {boolean} True if a matching vessel was selected.
      */
-    selectById(mmsi) {
-      if (mmsi === null || mmsi === undefined) return false;
-      const target = String(mmsi).trim();
+    selectById(id) {
+      if (id === null || id === undefined) return false;
+      const target = String(id).trim();
       if (!target) return false;
-      const record = state.records.byMmsi.get(target);
+      const record = recordFor(target);
       if (!record) return false;
       components.selection.selectVessel(record);
       return true;
@@ -505,12 +538,13 @@ export function createQueries({
 
     /**
      * Get info about the currently selected vessel.
-     * @returns {{ mmsi: string, name: string, latitude: number, longitude: number, speedKt: number|null, course: number|null, type: string }|null}
+     * @returns {{ id: string, mmsi: string, name: string, latitude: number, longitude: number, speedKt: number|null, course: number|null, type: string }|null}
      */
     getSelectedInfo() {
       const record = state.selectedRecord;
       if (!record) return null;
       return {
+        id: record.id,
         mmsi: record.mmsi,
         name: record.name,
         latitude: record.lat,
@@ -521,6 +555,33 @@ export function createQueries({
       };
     },
 
+    /**
+     * Where the selected vessel is drawn now, for a share link that names it:
+     * its id, its drawn position and the time that position stands for (the
+     * world time while the layer follows the clock, else its fix's time).
+     * @returns {{ id: string, position: Cesium.Cartesian3, observedAtMs: number|null }|null}
+     *   Null when the layer is off, nothing is selected or it is not drawn.
+     */
+    getSelectedFix() {
+      if (!state.feed.enabled) return null;
+      const record = state.selectedRecord;
+      if (!record?.id) return null;
+      const visual = components.rendering.getVisual(record);
+      const position = visual?.billboard?.position || visual?.position;
+      if (!position) return null;
+      const fixEpoch = record.lastPositionEpoch;
+      const observedAtMs = followsClock(vesselState)
+        ? vesselState.worldNow()
+        : Number.isFinite(fixEpoch)
+          ? fixEpoch * 1000
+          : (record.fixReceivedAtMs ?? null);
+      return {
+        id: record.id,
+        position,
+        observedAtMs: Number.isFinite(observedAtMs) ? observedAtMs : null,
+      };
+    },
+
     /**
      * Describe the selected vessel for the Cockpit bridge view.
      * @returns {object|null} `vesselCockpitInfo` fields plus `seaSurfaceHeightM`
@@ -546,16 +607,16 @@ export function createQueries({
     /**
      * Mark the vessel whose bridge the Cockpit camera occupies, or release it.
      * Its sprite, card and detection bracket stay hidden while it is held.
-     * @param {string|number|null} mmsi Subject MMSI, or null to release.
+     * @param {string|number|null} id Subject vessel id, or null to release.
      * @returns {boolean} Always true.
      */
-    setCockpitSubject(mmsi) {
-      const next = normalizeSelectionMmsi(mmsi);
-      if (state.cockpitSubjectMmsi === next) return true;
-      state.cockpitSubjectMmsi = next;
+    setCockpitSubject(id) {
+      const next = normalizeSelectionId(id);
+      if (state.cockpitSubjectId === next) return true;
+      state.cockpitSubjectId = next;
       // The ridden ship's trail runs from under the eye: hidden, its history
       // kept, while the bridge holds the ship it belongs to.
-      state.trail?.setVisible?.(!next || next !== state.trailMmsi);
+      state.trail?.setVisible?.(!next || next !== state.trailId);
       components.rendering.updateVisibility(true);
       return true;
     },
@@ -608,7 +669,7 @@ export function createQueries({
         if (!position) continue;
         result.push({
           position,
-          sourceId: record.mmsi,
+          sourceId: record.id,
           id: record.name || record.mmsi || 'VESSEL',
           type: 'SEA',
           skipLabel: record === selected,
@@ -676,7 +737,7 @@ export function createQueries({
     mapAnalystRecord,
     vesselDatumHeightM,
     reduceVesselSelection,
-    normalizeSelectionMmsi,
+    normalizeSelectionId,
     methods,
   };
 }

src/layers/vessels/radarContacts.test.mjs

@@ -134,7 +134,7 @@ test("the ridden ship's trail is hidden while the bridge holds it", () => {
   };
   const layer = layerWith([record('own', 0), record('other', 2)], {
     trail,
-    trailMmsi: 'own',
+    trailId: 'own',
   });
   layer.setCockpitSubject('own');
   assert.deepEqual(shown, [false]);

src/layers/vessels/records.js

@@ -3,17 +3,25 @@ import {
   SELECTED_PIN_REFRESHES,
 } from './recordPolicy.js';
 
-/** Normalize AIS display fields without allocating scene resources. */
+/**
+ * Normalize AIS display fields without allocating scene resources. `id` is the
+ * vessel's key, the stable id its source gives; a row that names none (an
+ * AIS feed's own rows) is keyed by its MMSI. `mmsi` is only an attribute,
+ * shown when known: vessels can share one. A row with neither is unkeyed.
+ */
 export function normalizeVessel(row) {
   const lat = Number(row.lat);
   const lon = Number(row.lon);
   if (!Number.isFinite(lat) || !Number.isFinite(lon)) return null;
+  const mmsi = String(row.mmsi || '').trim();
+  const id = String(row.id ?? mmsi).trim();
   return {
     lat,
     lon,
-    name: String(row.name || row.mmsi || 'VESSEL'),
-    mmsi: String(row.mmsi || '').trim(),
-    reference: row.reference ?? String(row.mmsi || '').trim(),
+    name: String(row.name || mmsi || 'VESSEL'),
+    id,
+    mmsi,
+    reference: row.reference ?? id,
     imo: String(row.imo || ''),
     type: String(row.type || ''),
     destination: String(row.destination || ''),
@@ -68,7 +76,7 @@ function motionBetween(record, next) {
 export class VesselRecords {
   constructor({ now = () => Date.now() } = {}) {
     this.now = now;
-    this.byMmsi = new Map();
+    this.byId = new Map();
     this.unkeyed = [];
     this.all = [];
   }
@@ -112,14 +120,14 @@ export class VesselRecords {
       if (!next) continue;
       next.receivedAtMs = receivedAtMs;
       stampFix(next, receivedAtMs, feedLatestEpoch);
-      if (!next.mmsi) {
+      if (!next.id) {
         effects.add(next);
         this.unkeyed.push(next);
         continue;
       }
-      if (seen.has(next.mmsi)) continue;
-      seen.add(next.mmsi);
-      const record = this.byMmsi.get(next.mmsi);
+      if (seen.has(next.id)) continue;
+      seen.add(next.id);
+      const record = this.byId.get(next.id);
       if (record) {
         const before = effects.beforeUpdate(record);
         // A feed re-serving a cached row repeats its fix: the fix keeps the
@@ -131,6 +139,7 @@ export class VesselRecords {
         if (replace) record.motion = null;
         else if (follow) record.motion = motionBetween(record, next);
         record.reference = next.reference;
+        record.mmsi = next.mmsi;
         record.receivedAtMs = next.receivedAtMs;
         record.lat = next.lat;
         record.lon = next.lon;
@@ -148,15 +157,15 @@ export class VesselRecords {
         effects.updated(record, before);
       } else {
         effects.add(next);
-        this.byMmsi.set(next.mmsi, next);
+        this.byId.set(next.id, next);
       }
     }
-    for (const [mmsi, record] of this.byMmsi) {
-      if (seen.has(mmsi)) continue;
+    for (const [id, record] of this.byId) {
+      if (seen.has(id)) continue;
       if (replace) {
         effects.remove(record, record === selectedRecord);
-        this.byMmsi.delete(mmsi);
-        effects.removed(mmsi);
+        this.byId.delete(id);
+        effects.removed(id);
         continue;
       }
       if (
@@ -179,18 +188,18 @@ export class VesselRecords {
       }
       // Selection teardown still sees the record before its store entry is removed.
       effects.remove(record, record === selectedRecord);
-      this.byMmsi.delete(mmsi);
-      effects.removed(mmsi);
+      this.byId.delete(id);
+      effects.removed(id);
     }
-    if (this.byMmsi.size + this.unkeyed.length > cap) {
-      for (const [mmsi, record] of this.byMmsi) {
-        if (this.byMmsi.size + this.unkeyed.length <= cap) break;
-        if (seen.has(mmsi) || record === selectedRecord) continue;
+    if (this.byId.size + this.unkeyed.length > cap) {
+      for (const [id, record] of this.byId) {
+        if (this.byId.size + this.unkeyed.length <= cap) break;
+        if (seen.has(id) || record === selectedRecord) continue;
         effects.remove(record, false);
-        this.byMmsi.delete(mmsi);
-        effects.removed(mmsi);
+        this.byId.delete(id);
+        effects.removed(id);
       }
     }
-    this.all = [...this.byMmsi.values(), ...this.unkeyed];
+    this.all = [...this.byId.values(), ...this.unkeyed];
   }
 }

src/layers/vessels/records.test.mjs

@@ -18,8 +18,8 @@ function setup() {
     beforeUpdate: (record) => record.type,
     updated: (record, before) => events.push(['update', record, before]),
     remove: (record, evicted) =>
-      events.push(['remove', record, evicted, store.byMmsi.has(record.mmsi)]),
-    removed: (id) => events.push(['removed', id, store.byMmsi.has(id)]),
+      events.push(['remove', record, evicted, store.byId.has(record.id)]),
+    removed: (id) => events.push(['removed', id, store.byId.has(id)]),
     staleSelected: (record) => events.push(['stale', record]),
   };
   return {
@@ -40,14 +40,14 @@ test('vessel reconciliation preserves record identity and first duplicate while
     row('222', { name: 'duplicate' }),
     row('bad', { lat: NaN }),
   ]);
-  assert.equal(probe.store.byMmsi.size, 2);
-  assert.equal(probe.store.byMmsi.get('222').name, '222');
-  const record = probe.store.byMmsi.get('111');
+  assert.equal(probe.store.byId.size, 2);
+  assert.equal(probe.store.byId.get('222').name, '222');
+  const record = probe.store.byId.get('111');
   probe.reconcile([row('111', { lat: 51.94, type: 'Tanker' })]);
-  assert.equal(probe.store.byMmsi.get('111'), record);
+  assert.equal(probe.store.byId.get('111'), record);
   assert.equal(record.lat, 51.94);
   assert.equal(probe.events.find((event) => event[0] === 'update')[2], 'Cargo');
-  assert.equal(probe.store.byMmsi.has('222'), false);
+  assert.equal(probe.store.byId.has('222'), false);
   for (const field of ['position', 'surfacePosition', 'normal', 'billboard'])
     assert.equal(Object.hasOwn(record, field), false);
   assert.deepEqual(structuredClone(record), record);
@@ -56,14 +56,14 @@ test('vessel reconciliation preserves record identity and first duplicate while
 test('selected vessel remains pinned for three complete misses and teardown precedes removal', () => {
   const probe = setup();
   probe.reconcile([row('111'), row('222')]);
-  const selectedRecord = probe.store.byMmsi.get('111');
+  const selectedRecord = probe.store.byId.get('111');
   for (let i = 1; i <= 3; i++) {
     probe.reconcile([row('222')], { selectedRecord });
-    assert.equal(probe.store.byMmsi.get('111'), selectedRecord);
+    assert.equal(probe.store.byId.get('111'), selectedRecord);
     assert.equal(selectedRecord.missedRefreshes, i);
   }
   probe.reconcile([row('222')], { selectedRecord });
-  assert.equal(probe.store.byMmsi.has('111'), false);
+  assert.equal(probe.store.byId.has('111'), false);
   const removal = probe.events.find(
     (event) => event[0] === 'remove' && event[1] === selectedRecord,
   );
@@ -77,13 +77,13 @@ test('selected vessel remains pinned for three complete misses and teardown prec
 test('partial retention respects age and row cap while preserving the selected contact', () => {
   const probe = setup();
   probe.reconcile([row('111'), row('222')], { cap: 2 });
-  const selectedRecord = probe.store.byMmsi.get('111');
+  const selectedRecord = probe.store.byId.get('111');
   probe.reconcile([row('333')], { complete: false, selectedRecord, cap: 2 });
-  assert.deepEqual([...probe.store.byMmsi.keys()], ['111', '333']);
+  assert.deepEqual([...probe.store.byId.keys()], ['111', '333']);
   assert.equal(selectedRecord.missedRefreshes, 1);
   probe.advance(5 * 60 * 1000);
   probe.reconcile([row('333')], { complete: false, selectedRecord, cap: 2 });
-  assert.equal(probe.store.byMmsi.has('111'), false);
+  assert.equal(probe.store.byId.has('111'), false);
   assert.equal(
     probe.events.find(
       (event) => event[0] === 'remove' && event[1] === selectedRecord,
@@ -107,7 +107,7 @@ test('unkeyed records rebuild on each refresh and numeric coercion keeps unknown
     ),
     true,
   );
-  assert.equal(probe.store.byMmsi.size, 0);
+  assert.equal(probe.store.byId.size, 0);
   assert.equal(probe.store.all.length, 1);
   assert.equal(normalizeVessel(row('bad', { lon: Infinity })), null);
 });
@@ -120,14 +120,14 @@ test("each fix keeps when it was first received and its refresh's newest fix", (
     row('333'),
   ]);
   for (const mmsi of ['111', '222', '333']) {
-    const record = probe.store.byMmsi.get(mmsi);
+    const record = probe.store.byId.get(mmsi);
     assert.equal(record.fixFeedEpoch, 1_800_000_030, mmsi);
     assert.equal(record.fixReceivedAtMs, 1000, mmsi);
   }
   // A new fix is stamped afresh.
   probe.advance(60_000);
   probe.reconcile([row('111', { last_position_epoch: 1_800_000_050 })]);
-  const record = probe.store.byMmsi.get('111');
+  const record = probe.store.byId.get('111');
   assert.equal(record.fixFeedEpoch, 1_800_000_050);
   assert.equal(record.fixReceivedAtMs, 61_000);
   // The same fix re-served by later polls keeps its first receipt, while
@@ -141,3 +141,43 @@ test("each fix keeps when it was first received and its refresh's newest fix", (
   assert.equal(record.fixFeedEpoch, 1_800_000_050);
   assert.equal(record.receivedAtMs, 91_000);
 });
+
+test('vessels are keyed by their source id; a shared MMSI is only an attribute', () => {
+  const probe = setup();
+  probe.reconcile([
+    row('123456789', { id: 'hull-a', name: 'A' }),
+    row('123456789', { id: 'hull-b', name: 'B' }),
+    row('', { id: 'hull-c', name: 'C' }),
+  ]);
+  assert.deepEqual(
+    [...probe.store.byId.keys()],
+    ['hull-a', 'hull-b', 'hull-c'],
+  );
+  assert.equal(probe.store.unkeyed.length, 0);
+  const [a, b, c] = probe.store.all;
+  assert.deepEqual([a.mmsi, b.mmsi, c.mmsi], ['123456789', '123456789', '']);
+  assert.equal(a.reference, 'hull-a');
+  // The number moves to another hull: the vessel keeps its id.
+  probe.reconcile([
+    row('', { id: 'hull-a', name: 'A' }),
+    row('123456789', { id: 'hull-b', name: 'B' }),
+    row('123456789', { id: 'hull-c', name: 'C' }),
+  ]);
+  assert.equal(probe.store.byId.get('hull-a'), a);
+  assert.equal(a.mmsi, '');
+  assert.equal(probe.store.byId.get('hull-c').mmsi, '123456789');
+});
+
+test('an AIS row with no id is keyed by its MMSI; one with neither is unkeyed', () => {
+  assert.deepEqual(
+    [
+      normalizeVessel(row('366999712')).id,
+      normalizeVessel(row('366999712')).mmsi,
+    ],
+    ['366999712', '366999712'],
+  );
+  const probe = setup();
+  probe.reconcile([row(''), row('', { id: '' })]);
+  assert.equal(probe.store.byId.size, 0);
+  assert.equal(probe.store.unkeyed.length, 2);
+});

src/layers/vessels/rendering.js

@@ -307,7 +307,7 @@ export function createRendering({
         if (visual.billboard) {
           // The bridge camera sits on this sprite; showing it would fill the view.
           visual.billboard.show =
-            visible && record.mmsi !== state.cockpitSubjectMmsi;
+            visible && record.id !== state.cockpitSubjectId;
           if (visible && doRotations && scene) {
             const rot = screenProjectedRotation(
               scene,
@@ -445,8 +445,7 @@ export function createRendering({
     const selected = state.selectedRecord;
     // From the bridge, the selected vessel is the viewer; its card would be
     // pinned to the camera position.
-    const selectedCarded =
-      selected && selected.mmsi !== state.cockpitSubjectMmsi;
+    const selectedCarded = selected && selected.id !== state.cockpitSubjectId;
     const entries = selectedCarded
       ? [components.cards.buildSelectedVesselCard(selected)]
       : [];
@@ -532,17 +531,17 @@ export function createRendering({
           VESSEL_CARD_FADE_DISTANCE_M,
         );
         if (!card.interactive) return card;
-        const mmsi = String(card.id || '').startsWith('vessel:')
+        const id = String(card.id || '').startsWith('vessel:')
           ? card.id.slice('vessel:'.length)
           : '';
+        const mmsi = state.records.byId.get(id)?.mmsi || '';
         return {
           ...card,
-          accessibilityLabel: t('Focus vessel {name}, MMSI {mmsi}', {
-            name: card.title,
-            mmsi,
-          }),
+          accessibilityLabel: mmsi
+            ? t('Focus vessel {name}, MMSI {mmsi}', { name: card.title, mmsi })
+            : t('Focus {label}', { label: card.title }),
           activate: () => {
-            const record = state.records.byMmsi.get(mmsi);
+            const record = state.records.byId.get(id);
             if (!record) return false;
             components.selection.selectAndFocusVessel(record);
             return true;
@@ -574,7 +573,8 @@ export function createRendering({
       text &&
       text !== 'VESSEL' &&
       !/^MMSI\s*\d+$/i.test(text) &&
-      text !== record.mmsi,
+      text !== record.mmsi &&
+      text !== record.id,
     );
   }
 

src/layers/vessels/selection.js

@@ -39,13 +39,15 @@ export function createSelection({
       if (!state.feed.enabled) return;
       // The bridge view owns the selection: a click on open water must not
       // deselect the vessel the camera is riding.
-      if (state.cockpitSubjectMmsi) return;
+      if (state.cockpitSubjectId) return;
       const picked = pickContact
         ? pickContact(viewer.scene, click.position)
         : viewer.scene.pick(click.position);
       const pickedId = resolvePickId(picked);
-      let record = pickedId ? state.records.byMmsi.get(pickedId) : null;
+      let record = pickedId ? state.records.byId.get(pickedId) : null;
       const rawId = picked?.id ?? picked?.primitive?.id;
+      // Every vessel record carries an `mmsi` field ('' when unknown); its
+      // key is `id`.
       const ownRecordPick =
         rawId && typeof rawId === 'object' && Object.hasOwn(rawId, 'mmsi');
 
@@ -85,10 +87,10 @@ export function createSelection({
       if (cycloneBackground && cardHit?.sourceId !== VESSEL_OVERLAY_SOURCE_ID)
         return;
       if (!record && cardHit) {
-        const mmsi = String(cardHit.entryId || '').startsWith('vessel:')
+        const id = String(cardHit.entryId || '').startsWith('vessel:')
           ? cardHit.entryId.slice('vessel:'.length)
           : null;
-        record = mmsi ? state.records.byMmsi.get(mmsi) || null : null;
+        record = id ? state.records.byId.get(id) || null : null;
         // A stale card id is not empty terrain and must not clear a newer
         // selection. The next paint will evict its hit rectangle.
         if (!record) return;
@@ -100,8 +102,8 @@ export function createSelection({
         selectAndFocusVessel(record);
       } else {
         const transition = components.queries.reduceVesselSelection({
-          selectedMmsi: state.selectedRecord?.mmsi,
-          pickedMmsi: null,
+          selectedId: state.selectedRecord?.id,
+          pickedId: null,
           gesture: 'click',
         });
         if (transition.action === 'deselect') clearVesselInspection();
@@ -123,17 +125,17 @@ export function createSelection({
   /** Select one live vessel and request one UI-owned camera transfer. */
 
   function selectAndFocusVessel(record) {
-    if (!record?.mmsi) return false;
+    if (!record?.id) return false;
     const transition = components.queries.reduceVesselSelection({
-      selectedMmsi: state.selectedRecord?.mmsi,
-      pickedMmsi: record.mmsi,
+      selectedId: state.selectedRecord?.id,
+      pickedId: record.id,
       gesture: 'click',
     });
     if (transition.action === 'select') selectVessel(record);
     requestWorldFocus({
       kind: 'vessel',
-      id: record.mmsi,
-      label: record.name || record.mmsi,
+      id: record.id,
+      label: record.name || record.mmsi || record.id,
       position:
         components.rendering.getVisual(record).billboard?.position ||
         components.rendering.getVisual(record).position,
@@ -160,7 +162,7 @@ export function createSelection({
   function onVesselKeyDown(event) {
     if (!state.feed.enabled || event.key !== 'Escape') return;
     const transition = components.queries.reduceVesselSelection({
-      selectedMmsi: state.selectedRecord?.mmsi,
+      selectedId: state.selectedRecord?.id,
       gesture: 'escape',
     });
     if (transition.action === 'deselect') {
@@ -169,8 +171,8 @@ export function createSelection({
   }
 
   function selectVessel(record) {
-    if (!record?.mmsi) return;
-    const reuseTrail = state.trailMmsi === record.mmsi;
+    if (!record?.id) return;
+    const reuseTrail = state.trailId === record.id;
     clearSelection({ preserveTrail: reuseTrail });
     state.selectedRecord = record;
     record.missedRefreshes = 0;
@@ -188,7 +190,7 @@ export function createSelection({
       selectEntityContext(record);
     }
     // Track-history trail (PRD F3/F4): seed with the current position + async
-    // backfill from the server-side per-MMSI ring buffer.
+    // backfill from the source's recent track for this vessel.
     if (reuseTrail) {
       components.tracking.appendSelectedVesselTrailFix(record);
     } else {
@@ -204,10 +206,10 @@ export function createSelection({
    */
 
   function registerSelectedContext(record) {
-    if (!record?.mmsi) return null;
+    if (!record?.id) return null;
     try {
       return registerEntityContext(record, {
-        id: `ais-${record.mmsi}`,
+        id: `ais-${record.id}`,
         layerId: 'ais-live-vessels',
         layerName: 'Live AIS Vessels',
         source: aisLiveVesselsLayer.source,
@@ -215,7 +217,8 @@ export function createSelection({
         latitude: record.lat,
         longitude: record.lon,
         properties: {
-          mmsi: record.mmsi,
+          vesselId: record.id,
+          mmsi: record.mmsi || null,
           type: record.type,
           speedKt: record.speed,
           course: record.course,

src/layers/vessels/snapshotRenderer.js

@@ -44,7 +44,7 @@ export function createVesselSnapshotRenderer({
             const nextIcon = rendering.shipIcon(record, selected);
             if (nextIcon !== prevIcon) visual.billboard.image = nextIcon;
           }
-          if (record.mmsi === state.trailMmsi)
+          if (record.id === state.trailId)
             tracking.appendSelectedVesselTrailFix(record);
           if (selected) {
             cards.updateSelectedVesselHud(record);
@@ -55,8 +55,8 @@ export function createVesselSnapshotRenderer({
           if (evicted) selection.clearVesselInspection({ evicted: true });
           rendering.removeRecordPrimitives(record);
         },
-        removed(mmsi) {
-          if (state.trailMmsi === mmsi) tracking.clearSelectedVesselTrail();
+        removed(id) {
+          if (state.trailId === id) tracking.clearSelectedVesselTrail();
         },
         staleSelected(record) {
           cards.updateSelectedVesselHud(record);
@@ -64,7 +64,7 @@ export function createVesselSnapshotRenderer({
       },
     );
     // The selected vessel at the new time: its trail starts there.
-    if (replace && state.selectedRecord && state.trailMmsi)
+    if (replace && state.selectedRecord && state.trailId)
       tracking.startSelectedVesselTrail(state.selectedRecord);
     state.lastVisibilityUpdate = 0;
     rendering.updateVisibility(true);

src/layers/vessels/state.js

@@ -86,14 +86,14 @@ export function createVesselState({ source, services }) {
     activeFocusCount: 0,
     activeLabelCount: 0,
     selectedRecord: null,
-    /** @type {string|null} MMSI whose bridge the Cockpit camera occupies; its sprite and card stay hidden. */
-    cockpitSubjectMmsi: null,
+    /** @type {string|null} Id of the vessel whose bridge the Cockpit camera occupies; its sprite and card stay hidden. */
+    cockpitSubjectId: null,
     /** @type {{setPositions: Function, clear: Function, destroy: Function}|null} Selected-vessel fading trail */
     trail: null,
     /** @type {Cesium.Cartesian3[]} Chronological trail vertices (oldest first) */
     trailPositions: [],
-    /** @type {string|null} MMSI that owns the active selected-vessel trail. */
-    trailMmsi: null,
+    /** @type {string|null} Id of the vessel that owns the active selected-vessel trail. */
+    trailId: null,
     /** @type {number} Monotonic token — invalidates in-flight backfill responses */
     trailBackfillToken: 0,
     trailAbort: null,

src/layers/vessels/testing.js

@@ -32,6 +32,11 @@ export function createTesting({
   function _setVesselStateForTest(options = {}) {
     components.lifecycle.resetState();
     const records = Array.isArray(options.records) ? options.records : [];
+    // A test record that names no id is keyed by its MMSI, as an AIS feed's
+    // own rows are (see normalizeVessel).
+    for (const record of [...records, options.selectedRecord])
+      if (record && typeof record === 'object' && record.id === undefined)
+        record.id = String(record.mmsi || '').trim();
     state.viewer = options.viewer || null;
     state.feed.enabled = options.enabled !== false;
     state.feed.loaded = options.loaded === true;
@@ -42,15 +47,15 @@ export function createTesting({
     state.feed.lastUpdate = options.lastUpdate ?? null;
     state.records.all = records;
     state.feed.count = records.length;
-    state.records.byMmsi = new Map(
+    state.records.byId = new Map(
       records
-        .filter((record) => record?.mmsi)
-        .map((record) => [record.mmsi, record]),
+        .filter((record) => record?.id)
+        .map((record) => [record.id, record]),
     );
     state.selectedRecord = options.selectedRecord || null;
     state.billboardCollection = options.billboardCollection || { remove() {} };
     state.trail = options.trail || null;
-    state.trailMmsi = options.trailMmsi || null;
+    state.trailId = options.trailId || null;
     state.trailPositions = Array.isArray(options.trailPositions)
       ? [...options.trailPositions]
       : [];
@@ -141,8 +146,8 @@ export function createTesting({
       lastMessageAt: state.feed.lastMessageAt,
       rawRowCount: state.feed.rawRowCount,
       acceptedRowCount: state.feed.acceptedRowCount,
-      selectedMmsi: state.selectedRecord?.mmsi || null,
-      trailMmsi: state.trailMmsi,
+      selectedId: state.selectedRecord?.id || null,
+      trailId: state.trailId,
       trailPositionCount: state.trailPositions.length,
       sessionId: state.feed.sessionId,
       firstConnectPhase: state.feed.firstConnectPhase,
@@ -166,14 +171,14 @@ export function createTesting({
   /**
    * Read lifecycle ownership state without exposing the mutable state object.
    * Test-only seam.
-   * @returns {{trailMmsi: string|null, trailPositionCount: number, vesselCount: number}}
+   * @returns {{trailId: string|null, trailPositionCount: number, vesselCount: number}}
    */
 
   function _getVesselStateForTest() {
     return {
-      trailMmsi: state.trailMmsi,
+      trailId: state.trailId,
       trailPositionCount: state.trailPositions.length,
-      vesselCount: state.records.byMmsi.size,
+      vesselCount: state.records.byId.size,
     };
   }
   return {

src/layers/vessels/tracking.js

@@ -86,7 +86,7 @@ export function createTracking({
     state.trailAbort?.abort();
     state.trailAbort = new AbortController();
     state.trailBackfillToken += 1;
-    state.trailMmsi = record.mmsi;
+    state.trailId = record.id;
     state.trailPositions = [];
     const current = vesselTrailPosition(record);
     if (current) state.trailPositions.push(current);
@@ -97,25 +97,21 @@ export function createTracking({
       });
     }
     if (state.trail) state.trail.setPositions(state.trailPositions);
-    backfillVesselTrail(
-      record.mmsi,
-      state.trailBackfillToken,
-      record.reference,
-    );
+    backfillVesselTrail(record.id, state.trailBackfillToken, record.reference);
   }
 
   /**
-   * Fire-and-forget backfill from the server-side per-MMSI ring buffer
+   * Fire-and-forget backfill from the server-side per-vessel ring buffer
    * (PRD F3 — "recent path" since server boot, not voyage history). Older
    * samples are spliced AHEAD of the live accumulation, capped at
    * TRAIL_MAX_POINTS (newest kept). Any failure (404/timeout/malformed)
    * silently keeps the live-only trail.
-   * @param {string} mmsi - MMSI of the selected vessel.
+   * @param {string} id - Key of the selected vessel.
    * @param {number} token - Backfill token captured at request time.
    * @returns {Promise<void>}
    */
 
-  async function backfillVesselTrail(mmsi, token, reference = mmsi) {
+  async function backfillVesselTrail(id, token, reference = id) {
     const owner = state.trailAbort;
     // Following the world clock, the track ends at the world's time.
     const atMs = followsClock(vesselState) ? vesselState.worldNow() : undefined;
@@ -139,7 +135,7 @@ export function createTracking({
       token !== state.trailBackfillToken
     )
       return;
-    if (state.trailMmsi !== mmsi) return;
+    if (state.trailId !== id) return;
 
     const older = [];
     for (const sample of samples) {
@@ -198,7 +194,7 @@ export function createTracking({
     state.trailAbort?.abort();
     state.trailAbort = null;
     state.trailBackfillToken += 1;
-    state.trailMmsi = null;
+    state.trailId = null;
     state.trailPositions = [];
     if (state.trail) state.trail.clear();
   }

src/share/follow.js

@@ -59,6 +59,12 @@ export const SHARE_VIEW_FOLLOW_OFFSET_DEFAULT = Object.freeze({
   pitch: -35,
 });
 
+/**
+ * The follow range a thing view can carry, in whole metres: 1 to this (the
+ * codec clamps to the same bound).
+ */
+export const SHARE_VIEW_FOLLOW_RANGE_MAX_M = 1e8;
+
 const EARTH_RADIUS_M = 6_371_000;
 const RAD = Math.PI / 180;
 
@@ -114,6 +120,27 @@ function enuBasis(lat, lon) {
 
 const dot = (a, b) => a[0] * b[0] + a[1] * b[1] + a[2] * b[2];
 
+/**
+ * The follow offset that puts the camera at `camera` (lat, lon, alt) while
+ * following an entity at `fix`: the inverse of {@link followCameraFor}, on
+ * the same sphere, in whole metres and degrees. Null when the camera is not
+ * above the entity's local horizontal (a view from below it, or through the
+ * earth, has no follow offset), or is at the entity.
+ */
+export function followOffsetFor(fix, camera) {
+  const at = toEcef(fix.lat, fix.lon, fix.alt);
+  const from = toEcef(camera.lat, camera.lon, camera.alt);
+  const basis = enuBasis(fix.lat, fix.lon);
+  const delta = [0, 1, 2].map((i) => from[i] - at[i]);
+  const local = {
+    east: dot(delta, basis.east),
+    north: dot(delta, basis.north),
+    up: dot(delta, basis.up),
+  };
+  if (!(local.up > 0)) return null;
+  return followOffsetFromEnu(local);
+}
+
 /**
  * Where the camera sits while following an entity at `fix` from `offset`,
  * and how it looks back at the entity, on a sphere of radius 6 371 000 m. A

src/share/viewCodec.js

@@ -62,7 +62,9 @@ import {
 export {
   SHARE_VIEW_ENTITY_KINDS,
   SHARE_VIEW_FOLLOW_OFFSET_DEFAULT,
+  SHARE_VIEW_FOLLOW_RANGE_MAX_M,
   followCameraFor,
+  followOffsetFor,
   followOffsetFromEnu,
   followOffsetToEnu,
 } from './follow.js';
@@ -387,8 +389,9 @@ const fieldNumber = (key) => FIELD_BY_KEY.get(key).number;
 
 /**
  * Fields inside the thing message (top-level field 13). Permanent. Fields 1–4
- * are the entity ids, one per SHARE_VIEW_ENTITY_KINDS code; exactly one is
- * present. The follow offset and the last-known fix are flat fields here, not
+ * are the entity ids, one per SHARE_VIEW_ENTITY_KINDS code, and field 13 is a
+ * vessel id that is a UUID, as its 16 bytes; exactly one of them is present.
+ * The follow offset and the last-known fix are flat fields here, not
  * sub-messages, to save their tag and length bytes.
  */
 export const SHARE_VIEW_THING_FIELDS = Object.freeze({
@@ -400,8 +403,17 @@ export const SHARE_VIEW_THING_FIELDS = Object.freeze({
   alt: 10, // sint metres, its last-known altitude
   ageS: 11, // sint, seconds the fix predates the created-at time (field 8)
   observedAt: 12, // epoch, when the fix was taken; only without a created-at
+  vesselUuid: 13, // LEN, 16 bytes: a vessel id that is a UUID
 });
 
+/**
+ * A vessel id that is a UUID, as a source's stable id may be: lowercase,
+ * dashed. It travels as its 16 bytes (thing field 13), not as text.
+ */
+export const SHARE_VIEW_UUID_GRAMMAR =
+  /^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$/;
+const UUID_BYTES = 16;
+
 /** The default of a field or flag for a view in `style`. */
 function defaultOf(entry, style) {
   if (entry.default !== BY_STYLE) return entry.default;
@@ -490,7 +502,10 @@ function normalizeEntityId(entry, value) {
       : typeof value === 'string'
         ? value.trim().toLowerCase()
         : null;
-  if (raw === null || !TRACKING_ID_GRAMMAR.test(raw)) return null;
+  if (raw === null) return null;
+  // A vessel's source may key it by a UUID, longer than the id grammar.
+  if (entry.kind === 'vessel' && SHARE_VIEW_UUID_GRAMMAR.test(raw)) return raw;
+  if (!TRACKING_ID_GRAMMAR.test(raw)) return null;
   if (entry.kind === 'satellite' && !/^[1-9]\d{0,14}$/.test(raw)) return null;
   return raw;
 }
@@ -795,6 +810,31 @@ const REGISTRY_BY_TOKEN = new Map(
 const charNumber = (char) => LAYER_STATE_TOKEN_ALPHABET.indexOf(char);
 const CANONICAL_INTEGER = /^(0|-?[1-9]\d{0,14})$/;
 
+/** The 16 bytes of a UUID in SHARE_VIEW_UUID_GRAMMAR. */
+function uuidBytes(id) {
+  const hex = id.replaceAll('-', '');
+  return Array.from({ length: UUID_BYTES }, (_, i) =>
+    Number.parseInt(hex.slice(i * 2, i * 2 + 2), 16),
+  );
+}
+
+/** The lowercase dashed UUID that `bytes` spell. */
+function uuidText(bytes) {
+  const hex = Array.from(bytes, (byte) =>
+    byte.toString(16).padStart(2, '0'),
+  ).join('');
+  return [
+    hex.slice(0, 8),
+    hex.slice(8, 12),
+    hex.slice(12, 16),
+    hex.slice(16, 20),
+    hex.slice(20),
+  ].join('-');
+}
+
+const isVesselUuid = (entry, id) =>
+  entry.kind === 'vessel' && SHARE_VIEW_UUID_GRAMMAR.test(id);
+
 function writeEntityId(writer, entry, id) {
   const field = entry.code;
   if (entry.idForm === 'hex24' && /^[0-9a-f]{6}$/.test(id))
@@ -895,7 +935,8 @@ function encodeThing(writer, view, state) {
   const f = SHARE_VIEW_THING_FIELDS;
   const d = SHARE_VIEW_FOLLOW_OFFSET_DEFAULT;
   const thing = new WireWriter();
-  writeEntityId(thing, entry, view.entity.id);
+  const uuid = isVesselUuid(entry, view.entity.id);
+  if (!uuid) writeEntityId(thing, entry, view.entity.id);
   const { range, heading, pitch } = view.offset;
   if (range !== d.range) thing.uintField(f.range, range);
   if (heading !== d.heading) thing.sintField(f.heading, signedAngle(heading));
@@ -914,6 +955,8 @@ function encodeThing(writer, view, state) {
     } else if (observed !== null)
       thing.sintField(f.observedAt, epochSeconds(observed));
   }
+  // Fields go in ascending order, so the UUID id (field 13) comes last.
+  if (uuid) thing.bytesField(f.vesselUuid, uuidBytes(view.entity.id));
   writer.bytesField(fieldNumber('thing'), thing.finish());
 }
 
@@ -1063,7 +1106,9 @@ const TOP_LEVEL_WIRE_TYPES = new Map(
 const THING_WIRE_TYPES = new Map([
   ...SHARE_VIEW_ENTITY_KINDS.map((e) => [e.code, [WIRE_VARINT, WIRE_LEN]]),
   ...Object.values(SHARE_VIEW_THING_FIELDS).map((n) => [n, [WIRE_VARINT]]),
+  [SHARE_VIEW_THING_FIELDS.vesselUuid, [WIRE_LEN]],
 ]);
+const VESSEL_ENTRY = SHARE_VIEW_ENTITY_KINDS.find((e) => e.kind === 'vessel');
 
 const unz = unzigzag;
 const CLOSED_ENUMS = new Set(['detectionMode', 'detectionAllocation']);
@@ -1258,8 +1303,18 @@ function decodeThing(reader, createdAtS, unknown) {
     ? followCameraFor(lastKnown, normalizeFollowOffset(offset))
     : null;
   const present = SHARE_VIEW_ENTITY_KINDS.filter((e) => fields.has(e.code));
-  if (present.length > 1)
+  const uuid = fields.get(F.vesselUuid);
+  if (present.length + (uuid ? 1 : 0) > 1)
     throw new ShareWireError('duplicate-field', 'thing entity id');
+  if (uuid) {
+    const bytes = uuid.len.rest();
+    if (bytes.length !== UUID_BYTES)
+      throw new ShareWireError('bad-length', 'thing vessel id');
+    return {
+      camera,
+      view: thingView(VESSEL_ENTRY.kind, uuidText(bytes), offset, lastKnown),
+    };
+  }
   const entry = present[0];
   if (!entry) {
     // A newer app's entity kind uses a thing field this decoder skipped.

src/share/viewCodec.test.mjs

@@ -43,14 +43,17 @@ import {
   BY_STYLE,
   SHARE_VIEW_FLAGS,
   SHARE_VIEW_FOLLOW_OFFSET_DEFAULT,
+  SHARE_VIEW_FOLLOW_RANGE_MAX_M,
   SHARE_VIEW_STYLE_DEFAULTS,
   SHARE_VIEW_LAYER_OPTION_ABSENT,
   SHARE_VIEW_PANELS,
   SHARE_VIEW_STYLE_PARAMS,
+  SHARE_VIEW_THING_FIELDS,
   createDefaultShareViewState,
   decodeShareView,
   encodeShareView,
   followCameraFor,
+  followOffsetFor,
   followOffsetFromEnu,
   followOffsetToEnu,
   layerTokenFromNumber,
@@ -149,6 +152,7 @@ function randomState(random) {
               String(int(100000000, 999999999)),
               '002442000',
               'tmp-7',
+              '0770e3ca-b896-c307-f499-4f9df2b8f86b',
             ])
           : pick(random, [
               int(0, 0xffffff).toString(16).padStart(6, '0'),
@@ -1359,3 +1363,211 @@ test('the world time is written only away from live, and may lie ahead', () => {
       encodeShareView({ sharedAtMs: NOW_MS }).length,
   );
 });
+
+/* ---------------- vessel ids that are UUIDs ---------------- */
+
+const VESSEL_UUID = '0770e3ca-b896-c307-f499-4f9df2b8f86b';
+const VESSEL_FIX = {
+  lat: 51.9301,
+  lon: 4.0512,
+  alt: 47,
+  observedAtMs: NOW_MS - 30_000,
+};
+const VESSEL_OFFSET = { range: 3200, heading: 20, pitch: -30 };
+const vesselView = (id, extra = {}) => ({
+  view: {
+    kind: 'thing',
+    entity: { kind: 'vessel', id },
+    offset: VESSEL_OFFSET,
+    lastKnown: VESSEL_FIX,
+  },
+  sharedAtMs: NOW_MS,
+  ...extra,
+});
+
+/** A thing message's bytes, wrapped as a whole payload's code. */
+function thingCode(write) {
+  const thing = new WireWriter();
+  write(thing);
+  const writer = new WireWriter();
+  writer.bytes.push(1);
+  writer.bytesField(13, thing.finish());
+  return hashOf(writer.finish());
+}
+
+test('a vessel id that is a UUID travels as its 16 bytes and round-trips', () => {
+  assert.equal(SHARE_VIEW_THING_FIELDS.vesselUuid, 13);
+  const code = assertRoundTrip(vesselView(VESSEL_UUID));
+  const { state } = decodeOk(code);
+  assert.deepEqual(state.view.entity, { kind: 'vessel', id: VESSEL_UUID });
+  // Upper case is the same id: the decoder gives it back lowercase.
+  assert.equal(
+    decodeOk(encodeShareView(vesselView(VESSEL_UUID.toUpperCase()))).state.view
+      .entity.id,
+    VESSEL_UUID,
+  );
+  // 16 bytes and a two-byte tag and length, not 36 characters of text.
+  const aircraft = encodeShareView({
+    ...vesselView('a1b2c3'),
+    view: {
+      ...vesselView('a1b2c3').view,
+      entity: { kind: 'aircraft', id: 'a1b2c3' },
+    },
+  });
+  assert.equal(aircraft.length, 44);
+  assert.equal(code.length, 62);
+  assert.equal(
+    payloadBytes(code).length - payloadBytes(aircraft).length,
+    18 - 5,
+    'the id costs 18 bytes where an ICAO address costs 5',
+  );
+  // The id field comes last, after the fix, in ascending order.
+  const bytes = payloadBytes(code);
+  assert.deepEqual(
+    [...bytes.slice(-18)],
+    [
+      0x6a,
+      16,
+      ...VESSEL_UUID.replaceAll('-', '')
+        .match(/../g)
+        .map((h) => parseInt(h, 16)),
+    ],
+  );
+  // A UUID form is only a vessel's: other kinds keep the id grammar.
+  for (const kind of ['aircraft', 'military_aircraft', 'satellite'])
+    assert.deepEqual(
+      normalizeShareViewState({
+        view: { kind: 'thing', entity: { kind, id: VESSEL_UUID } },
+      }).view,
+      { kind: 'place' },
+    );
+  // Near-UUIDs are not UUIDs, and are longer than the id grammar allows.
+  for (const id of [VESSEL_UUID.replaceAll('-', '') + '0', `${VESSEL_UUID}0`])
+    assert.deepEqual(
+      normalizeShareViewState({
+        view: { kind: 'thing', entity: { kind: 'vessel', id } },
+      }).view,
+      { kind: 'place' },
+    );
+});
+
+test('MMSI and short text vessel ids, and links made before UUIDs, are unchanged', () => {
+  // Codes written before vessel ids could be UUIDs.
+  const before = {
+    'AUCAn8wYahkYoPH_rgEogBkwKDg7QIqyP0iA-QRQXlg8Ag': '366999712',
+    AUCAn8wYah4aCTAwMjQ0MjAwMCiAGTAoODtAirI_SID5BFBeWDyl: '002442000',
+  };
+  for (const [code, id] of Object.entries(before)) {
+    assert.equal(encodeShareView(vesselView(id)), code);
+    const { state } = decodeOk(code);
+    assert.deepEqual(state.view, {
+      kind: 'thing',
+      entity: { kind: 'vessel', id },
+      offset: VESSEL_OFFSET,
+      lastKnown: VESSEL_FIX,
+    });
+  }
+  // A camera-only vessel view with a short text id, as before.
+  const tmp = 'ARCgnAEYwLgCagcaBXRtcC03GQ';
+  assert.equal(
+    encodeShareView({
+      lat: 1,
+      lon: 2,
+      view: { kind: 'thing', entity: { kind: 'vessel', id: 'tmp-7' } },
+    }),
+    tmp,
+  );
+  assert.equal(decodeOk(tmp).state.view.entity.id, 'tmp-7');
+});
+
+test('a UUID vessel id with another id, or of the wrong length, is malformed', () => {
+  const uuid = VESSEL_UUID.replaceAll('-', '')
+    .match(/../g)
+    .map((h) => parseInt(h, 16));
+  const reason = (code) => decodeShareView(code, { nowMs: NOW_MS }).reason;
+  // Two entity ids: the UUID and an MMSI, or an aircraft's address.
+  assert.equal(
+    reason(thingCode((t) => t.uintField(3, 366999712).bytesField(13, uuid))),
+    'duplicate-field',
+  );
+  assert.equal(
+    reason(thingCode((t) => t.uintField(1, 0xa1b2c3).bytesField(13, uuid))),
+    'duplicate-field',
+  );
+  assert.equal(
+    reason(thingCode((t) => t.bytesField(13, uuid).bytesField(13, uuid))),
+    'duplicate-field',
+  );
+  for (const bytes of [uuid.slice(0, 15), [...uuid, 0], []])
+    assert.equal(
+      reason(thingCode((t) => t.bytesField(13, bytes))),
+      'bad-length',
+    );
+  // The field is LEN only.
+  assert.equal(
+    reason(thingCode((t) => t.uintField(13, 5))),
+    'wire-type-mismatch',
+  );
+  // The 16 bytes alone are a vessel; any bytes spell a UUID.
+  assert.deepEqual(
+    decodeOk(thingCode((t) => t.bytesField(13, new Array(16).fill(0xff)))).state
+      .view.entity,
+    { kind: 'vessel', id: 'ffffffff-ffff-ffff-ffff-ffffffffffff' },
+  );
+});
+
+test('a decoder that predates UUID vessel ids opens the view at its derived camera', () => {
+  // Such a decoder skips thing field 13 as it skips any unknown field: the
+  // same payload with the id under a field this decoder does not know.
+  const bytes = [...payloadBytes(encodeShareView(vesselView(VESSEL_UUID)))];
+  const at = bytes.length - 18;
+  assert.equal(bytes[at], 0x6a);
+  bytes[at] = 0xf2; // field 30, LEN
+  bytes.splice(at + 1, 0, 0x01);
+  // The thing message grew by a byte: its own length too.
+  const thingLength = bytes.indexOf(0x6a) + 1;
+  bytes[thingLength] += 1;
+  const result = decodeOk(hashOf(bytes));
+  assert.equal(result.fallback, 'unknown-entity-kind');
+  assert.deepEqual(result.state.view, { kind: 'place' });
+  const camera = followCameraFor(VESSEL_FIX, VESSEL_OFFSET);
+  assert.equal(result.state.lat, Math.round(camera.lat * 1e4) / 1e4);
+  assert.equal(result.state.lon, Math.round(camera.lon * 1e4) / 1e4);
+});
+
+test('the follow offset for a camera is the inverse of followCameraFor', () => {
+  const fix = { lat: 51.9301, lon: 4.0512, alt: 47 };
+  for (const offset of [
+    { range: 3200, heading: 20, pitch: -30 },
+    { range: 250, heading: 300, pitch: -5 },
+    { range: 80_000, heading: 135, pitch: -70 },
+    { range: 2_000_000, heading: 0, pitch: -89 },
+  ])
+    assert.deepEqual(
+      followOffsetFor(fix, followCameraFor(fix, offset)),
+      offset,
+    );
+  // The codec carries ranges up to the bound a subject is checked against.
+  const far = {
+    range: SHARE_VIEW_FOLLOW_RANGE_MAX_M + 5,
+    heading: 0,
+    pitch: -35,
+  };
+  assert.equal(
+    normalizeShareViewState({
+      view: { kind: 'thing', entity: { kind: 'vessel', id: '1' }, offset: far },
+    }).view.offset.range,
+    SHARE_VIEW_FOLLOW_RANGE_MAX_M,
+  );
+  // A camera below the entity's horizontal, or at it, has no offset.
+  assert.equal(
+    followOffsetFor(fix, { lat: 51.95, lon: 4.0512, alt: 40 }),
+    null,
+  );
+  assert.equal(followOffsetFor(fix, fix), null);
+  // Far round the curve of the earth at low height: below its horizon.
+  assert.equal(
+    followOffsetFor(fix, { lat: 53.9, lon: 4.0512, alt: 1000 }),
+    null,
+  );
+});

src/sources/live/contract.js

@@ -8,6 +8,11 @@
  * getTrack(reference, { signal }). References are opaque to consumers.
  * Snapshots describe coverage and completeness independently of freshness.
  * Records contain observation data only, with no scene objects or transport data.
+ * Every record has a stable `id` (a non-empty string) that keys it across
+ * snapshots. A vessel record's `id` is whatever its source gives, such as a
+ * provider id; its `mmsi` is an optional attribute ('' or absent when
+ * unknown), never its key, since vessels can share an MMSI. A source that
+ * only has MMSIs uses the MMSI as the id.
  *
  * A source may also declare a timeline (see readSnapshotTimeline): it can
  * answer a snapshot at a given time, so the layer follows the world clock.
@@ -155,8 +160,9 @@ export function httpError(response, source) {
  * malformed: `{ coverage(), stepMs, subscribe? }`. `coverage()` returns the
  * span `{start, end}` (epoch ms) the source can answer a snapshot for, or
  * null while it does not know yet; `stepMs` is the spacing of its snapshots;
- * the optional `subscribe(listener)` tells of a change in coverage and
- * returns the unsubscribe.
+ * the optional `subscribe(listener)` tells of a change in coverage, or of a
+ * better answer for a time already answered (a paused layer then loads the
+ * time shown again), and returns the unsubscribe.
  * @param {object|null|undefined} source
  * @returns {{coverage: () => ({start: number, end: number}|null),
  *   stepMs: number, subscribe: ((listener: () => void) => () => void)|null}|null}

src/sources/live/contract.test.mjs

@@ -9,6 +9,7 @@ import {
   openSkySnapshot,
   readsbSnapshot,
   readSnapshotTimeline,
+  vesselSnapshot,
 } from './index.js';
 
 const now = 1800000000000;
@@ -196,6 +197,7 @@ test('vessel identity, opaque reference and heading/course remain distinct, unkn
     'opaque-reference',
   );
   assert.equal(row.id, '123456789');
+  assert.equal(row.mmsi, '123456789');
   assert.equal(row.reference, 'opaque-reference');
   assert.equal(row.headingDeg, 45);
   assert.equal(row.courseDeg, 60);
@@ -525,3 +527,62 @@ test('a source declares a timeline only with a coverage reader and a positive st
   stop();
   assert.equal(listeners.length, 0);
 });
+
+test('vessel snapshots key rows by the id idFor gives; the MMSI is an attribute', () => {
+  const at = { lat: 30, lon: -97 };
+  const rows = [
+    { uuid: 'hull-a', mmsi: '123456789', ...at },
+    { uuid: 'hull-b', mmsi: '123456789', ...at },
+    { uuid: 'hull-c', mmsi: 'not-an-mmsi', ...at },
+    { uuid: 'hull-a', mmsi: '123456789', ...at },
+  ];
+  const keyed = vesselSnapshot(
+    { rows },
+    { idFor: (row) => row.uuid || row.mmsi },
+  );
+  assert.deepEqual(
+    keyed.records.map(({ id, mmsi, reference }) => [id, mmsi, reference]),
+    [
+      ['hull-a', '123456789', 'hull-a'],
+      ['hull-b', '123456789', 'hull-b'],
+      ['hull-c', '', 'hull-c'],
+    ],
+  );
+  assert.equal(keyed.rejectedCount, 1, 'a repeated id is one vessel');
+
+  // AISStream rows have only MMSIs: one MMSI is one vessel, as before.
+  const ais = vesselSnapshot({ rows });
+  assert.deepEqual(
+    ais.records.map(({ id, mmsi, reference }) => [id, mmsi, reference]),
+    [
+      ['123456789', '123456789', '123456789'],
+      ['not-an-mmsi', '', 'not-an-mmsi'],
+    ],
+  );
+  const referenced = vesselSnapshot(
+    { rows: rows.slice(0, 1) },
+    { idFor: (row) => row.uuid, referenceFor: (row) => `track:${row.uuid}` },
+  );
+  assert.equal(referenced.records[0].reference, 'track:hull-a');
+});
+
+test('a vessel with no name is not named by its id; a ten-digit MMSI is an MMSI', () => {
+  const at = { lat: 30, lon: -97 };
+  const [unnamed, longMmsi, named] = vesselSnapshot(
+    {
+      rows: [
+        { uuid: 'f00dcafe-0000-0000-0000-000000000001', ...at },
+        { uuid: 'hull-x', mmsi: '1234567890', ...at },
+        { uuid: 'hull-y', mmsi: '244123456', name: 'EVER GIVEN', ...at },
+      ],
+    },
+    { idFor: (row) => row.uuid },
+  ).records;
+  assert.equal(unnamed.name, '');
+  assert.equal(unnamed.mmsi, '');
+  assert.deepEqual(
+    [longMmsi.mmsi, longMmsi.name],
+    ['1234567890', '1234567890'],
+  );
+  assert.equal(named.name, 'EVER GIVEN');
+});

src/sources/live/vessels.js

@@ -1,18 +1,41 @@
 import { coordinates, epoch, finite, LiveSourceError } from './contract.js';
 
-/** AIS positions are sea-surface observations; heading and course are distinct. */
-export function normalizeVesselObservation(row, reference = null) {
-  const id = String(row?.mmsi || row?.input_identifier || '').trim();
+/** An MMSI is up to ten digits (AIS carries it in 30 bits); anything else a
+ * row names it is not one. */
+const MMSI_PATTERN = /^\d{1,10}$/;
+
+/** The row's MMSI when it carries one that looks like an MMSI, else ''. */
+function vesselMmsi(row) {
+  const text = String(row?.mmsi ?? '').trim();
+  return MMSI_PATTERN.test(text) ? text : '';
+}
+
+/** A row's stable id when its source names none: its MMSI or identifier. */
+function defaultVesselId(row) {
+  return String(row?.mmsi || row?.input_identifier || '');
+}
+
+/**
+ * AIS positions are sea-surface observations; heading and course are distinct.
+ * `id` is the vessel's key; an MMSI is not one (vessels share numbers and a
+ * number can move to another hull), so `mmsi` is an attribute, '' when the
+ * row has none. A row with no id of its own is keyed by its MMSI.
+ */
+export function normalizeVesselObservation(row, reference = null, id = null) {
+  const key = String(id ?? defaultVesselId(row)).trim();
   const latitude = finite(row?.lat),
     longitude = finite(row?.lon);
-  if (!id || !coordinates(latitude, longitude)) return null;
+  if (!key || !coordinates(latitude, longitude)) return null;
+  const mmsi = vesselMmsi(row);
   const speedKts = finite(row.speed);
   return {
-    id,
-    reference: reference ?? id,
+    id: key,
+    mmsi,
+    reference: reference ?? key,
     latitude,
     longitude,
-    name: String(row.name || row.input_name || id),
+    // A source's own id is not a name: a vessel with none is unnamed.
+    name: String(row.name || row.input_name || mmsi || defaultVesselId(row)),
     imo: String(row.imo || ''),
     type: String(row.type_specific || row.type || ''),
     destination: String(row.destination || ''),
@@ -26,12 +49,21 @@ export function normalizeVesselObservation(row, reference = null) {
   };
 }
 
+/**
+ * A vessel snapshot from a `{ rows }` payload. `idFor(row)` gives a row's
+ * stable id (its MMSI or identifier by default); rows are deduped by that id,
+ * so two vessels sharing an MMSI stay two vessels. A source whose rows carry
+ * an id of their own passes it, such as `idFor: (row) => row.uuid || row.mmsi`.
+ * `referenceFor(row)` gives the reference its track is asked for by; the id
+ * by default.
+ */
 export function vesselSnapshot(
   payload,
   {
     source = 'AISStream',
     coverage = 'received AIS positions',
-    referenceFor = (row) => String(row.mmsi || row.input_identifier || ''),
+    idFor = defaultVesselId,
+    referenceFor = null,
   } = {},
 ) {
   if (!Array.isArray(payload?.rows))
@@ -40,8 +72,13 @@ export function vesselSnapshot(
   const records = [],
     ids = new Set();
   for (const row of rows) {
-    const record = normalizeVesselObservation(row);
-    if (record) record.reference = referenceFor(row);
+    const record = normalizeVesselObservation(
+      row,
+      null,
+      row && typeof row === 'object' ? idFor(row) : null,
+    );
+    // A row's track is asked for by its id unless the source says otherwise.
+    if (record && referenceFor) record.reference = referenceFor(row);
     if (record && !ids.has(record.id)) {
       records.push(record);
       ids.add(record.id);

src/time/snapshotTimeline.js

@@ -279,6 +279,13 @@ export function createSnapshotTimeline({
     } else keepUp(timeMs, state);
   }
 
+  /** Load the time shown afresh. */
+  function reloadShown() {
+    if (!started || clock.isLive()) return;
+    failedUntil = -Infinity;
+    jumpTo(clock.getState().timeMs);
+  }
+
   return {
     /** The source's timeline while the layer follows the clock, else null. */
     get timeline() {
@@ -304,16 +311,17 @@ export function createSnapshotTimeline({
         clock.register({ id, coverage: () => span() }),
         clock.subscribe(follow),
       ];
-      const unsubscribe = timeline.subscribe?.(() => clock.coverageChanged());
+      // A source tells of new coverage, or of a better answer for times it
+      // has answered; paused, a time already shown is loaded again.
+      const unsubscribe = timeline.subscribe?.(() => {
+        clock.coverageChanged();
+        if (!clock.isPlaying() && lead !== null && !inflight) reloadShown();
+      });
       if (typeof unsubscribe === 'function') releases.push(unsubscribe);
       follow(clock.getState());
     },
     /** Load the time shown afresh, as when the area the layer asks for moved. */
-    reload() {
-      if (!started || clock.isLive()) return;
-      failedUntil = -Infinity;
-      jumpTo(clock.getState().timeMs);
-    },
+    reload: () => reloadShown(),
     /** The layer is off: stop following and drop what loads. */
     stop() {
       if (!started) return;

src/time/snapshotTimeline.test.mjs

@@ -302,3 +302,35 @@ test('a layer never has two loads out: the older is aborted before a newer start
   h.follower.stop();
   assert.equal(live(), 0);
 });
+
+test('a source that tells of a better answer has the paused time loaded again, not a playing one', async () => {
+  const h = harness();
+  h.follower.start();
+  const at = WALL - 600_000;
+  h.clock.seek(at);
+  await flush();
+  await h.answer();
+  const before = loads(h.calls).length;
+  for (const listener of h.coverageListeners) listener();
+  await flush();
+  assert.equal(loads(h.calls).length, before + 1);
+  assert.equal(loads(h.calls).at(-1).atMs, at);
+  await h.answer(h.pending.length - 1);
+  h.clock.play();
+  const playing = loads(h.calls).length;
+  for (const listener of h.coverageListeners) listener();
+  await flush();
+  assert.ok(
+    loads(h.calls)
+      .slice(playing)
+      .every((call) => call.atMs !== at),
+    'playing, the time shown is not loaded again',
+  );
+  h.clock.goLive();
+  await flush();
+  const live = loads(h.calls).length;
+  for (const listener of h.coverageListeners) listener();
+  await flush();
+  assert.equal(loads(h.calls).length, live, 'live, nothing is loaded');
+  h.follower.stop();
+});

src/tools/queries/maritime.js

@@ -28,6 +28,14 @@ const MMSI_SCHEMA = Object.freeze({
   pattern: '^\\d{5,10}$',
   description: 'Maritime Mobile Service Identity, such as "366999712".',
 });
+const VESSEL_ID_SCHEMA = Object.freeze({
+  type: 'string',
+  minLength: 1,
+  maxLength: 128,
+  description:
+    'The vessel id a vessel search returned. Vessels can share an MMSI; ' +
+    'the id names one of them.',
+});
 const MAX_TRACK_POINTS = 200;
 const ALL_VESSELS = 1_000_000;
 
@@ -47,10 +55,13 @@ const vesselDestination = (value) => {
   return destination && /\p{L}/u.test(destination) ? destination : null;
 };
 
+// `id` is the vessel's key; `mmsi` is its MMSI when known (vessels can share
+// one), else null.
 function vesselRow(record, from) {
   const point = { lat: record.latitude, lon: record.longitude };
   return {
-    mmsi: record.id,
+    id: record.id,
+    mmsi: text(record.mmsi),
     name: text(record.name),
     imo: text(record.imo),
     type: vesselType(record.type),
@@ -194,7 +205,7 @@ export const findVessel = defineTool({
     const [key] = given;
     const wanted = args[key].trim().toUpperCase();
     const matches = {
-      mmsi: (record) => record.id === wanted,
+      mmsi: (record) => String(record.mmsi ?? '') === wanted,
       imo: (record) => String(record.imo).replace(/^IMO/i, '') === wanted,
       name: (record) => String(record.name).toUpperCase().includes(wanted),
     }[key];
@@ -227,25 +238,40 @@ export const getVesselTrack = defineTool({
   name: 'get_vessel_track',
   title: 'Vessel track',
   description:
-    'Recent positions of one ship by MMSI, oldest first. Long tracks are ' +
-    `evenly thinned to at most ${MAX_TRACK_POINTS} points.`,
+    'Recent positions of one ship by its vessel id or MMSI, oldest first. ' +
+    `Long tracks are evenly thinned to at most ${MAX_TRACK_POINTS} points.`,
   inputSchema: {
     type: 'object',
-    properties: { mmsi: MMSI_SCHEMA },
-    required: ['mmsi'],
+    properties: { id: VESSEL_ID_SCHEMA, mmsi: MMSI_SCHEMA },
     additionalProperties: false,
   },
   requires: ['vessels'],
   async run(args, { services, signal }) {
-    const track = await services.vessels.getTrack(args.mmsi, { signal });
+    const given = ['id', 'mmsi'].filter((key) => args[key] != null);
+    if (given.length !== 1)
+      throw new ToolError(
+        'invalid_arguments',
+        'Give exactly one of id or mmsi',
+      );
+    const [key] = given;
+    const wanted = String(args[key]).trim();
+    // A track is asked for by the source's reference for the vessel, which
+    // for an id is the reported vessel's; an MMSI is passed as it is.
+    let reference = wanted;
+    if (key === 'id') {
+      const snapshot = await readVessels(services, signal);
+      const record = snapshot.records.find((item) => item.id === wanted);
+      reference = record?.reference ?? wanted;
+    }
+    const track = await services.vessels.getTrack(reference, { signal });
     const points = track.records
       .filter((point) => Number.isFinite(point.observedAtMs))
       .sort((a, b) => a.observedAtMs - b.observedAtMs);
     const kept = thinEvenly(points, MAX_TRACK_POINTS);
     return {
       summary: points.length
-        ? `${countNoun(points.length, 'position')} for ${args.mmsi} from ${isoTime(points[0].observedAtMs)} to ${isoTime(points.at(-1).observedAtMs)}.`
-        : `No recent track is available for ${args.mmsi}.`,
+        ? `${countNoun(points.length, 'position')} for ${wanted} from ${isoTime(points[0].observedAtMs)} to ${isoTime(points.at(-1).observedAtMs)}.`
+        : `No recent track is available for ${wanted}.`,
       data: {
         view: kept.length
           ? suggestView(services, {
@@ -254,7 +280,7 @@ export const getVesselTrack = defineTool({
               altitudeM: 20_000,
             })
           : null,
-        mmsi: args.mmsi,
+        ...(key === 'id' ? { id: wanted } : { mmsi: wanted }),
         total: points.length,
         returned: kept.length,
         thinned: kept.length < points.length,

src/tools/queries/maritime.test.mjs

@@ -5,8 +5,10 @@ import { LiveSourceError } from '../../sources/live/contract.js';
 import { createVesselSource } from '../../sources/live/standalone.js';
 import { AISSTREAM_CACHE_MAX } from '../../../server/providers/vessels/ais-store.js';
 
+// An AIS source's vessel: keyed by its MMSI, which it also reports.
 const vessel = (id, latitude, longitude, extra = {}) => ({
   id,
+  mmsi: id,
   reference: id,
   latitude,
   longitude,
@@ -79,6 +81,7 @@ test('vessels in an area are nearest first and filterable by type', async () =>
     ['366999712', '538001234'],
   );
   assert.deepEqual(all.data.rows[0], {
+    id: '366999712',
     mmsi: '366999712',
     name: 'GOLDEN BEAR',
     imo: '9123456',
@@ -164,6 +167,53 @@ test('vessel tracks are ordered and drop untimed positions', async () => {
   );
 });
 
+test('vessels sharing an MMSI are found as two, each by its own id', async () => {
+  const shared = [
+    vessel('hull-a', 37.81, -122.41, { mmsi: '366999712', name: 'A' }),
+    vessel('hull-b', 37.79, -122.42, {
+      mmsi: '366999712',
+      name: 'B',
+      reference: 'track:hull-b',
+    }),
+    vessel('hull-c', 37.8, -122.4, { mmsi: undefined, name: 'C' }),
+  ];
+  const tracks = [];
+  const catalog = composeCatalog({
+    tools: coreTools,
+    services: {
+      vessels: {
+        getSnapshot: async () => ({ records: shared, freshness: 'current' }),
+        getTrack: async (reference) => {
+          tracks.push(reference);
+          return { records: [] };
+        },
+      },
+    },
+  });
+  const found = await catalog.call('find_vessel', { mmsi: '366999712' });
+  assert.deepEqual(
+    found.data.rows.map((row) => [row.id, row.mmsi]),
+    [
+      ['hull-a', '366999712'],
+      ['hull-b', '366999712'],
+    ],
+  );
+  const area = await catalog.call('vessels_in_area', { area: bay });
+  assert.deepEqual(
+    area.data.rows.find((row) => row.id === 'hull-c').mmsi,
+    null,
+    'a vessel with no MMSI says so',
+  );
+  const track = await catalog.call('get_vessel_track', { id: 'hull-b' });
+  assert.deepEqual(tracks, ['track:hull-b'], "asked by the vessel's reference");
+  assert.equal(track.data.id, 'hull-b');
+  assert.equal(track.summary, 'No recent track is available for hull-b.');
+  await assert.rejects(
+    catalog.call('get_vessel_track', { id: 'hull-b', mmsi: '366999712' }),
+    /exactly one/,
+  );
+});
+
 test('a missing AIS key surfaces as an unavailable feed', async () => {
   const keyless = {
     getSnapshot: async () => {

src/ui/applicationShell.js

@@ -472,7 +472,12 @@ export class StyleManager extends ShellFacade {
       initialShareCode,
     });
     this.shareLinkManager.setFollowSubjectProvider(({ nowMs }) =>
-      readShareFollowSubject({ viewer: this.viewer, nowMs }),
+      readShareFollowSubject({
+        viewer: this.viewer,
+        nowMs,
+        readSelectedVessel: () =>
+          this.services.aisLiveVesselsLayer?.getSelectedFix?.() ?? null,
+      }),
     );
     this.shareLinkManager.setPanelStateProvider(() =>
       this._buildSharePanelState(),

src/ui/cockpitBridge.test.mjs

@@ -15,6 +15,7 @@ import { vesselCockpitInfo } from '../layers/vessels/cockpitSubject.js';
 import { VesselRecords } from '../layers/vessels/records.js';
 
 const RECORD = Object.freeze({
+  id: '211000000',
   mmsi: '211000000',
   name: 'NORDIC STAR',
   type: '70',
@@ -65,9 +66,9 @@ function vesselLayer(record) {
       enabled && selected
         ? { ...vesselCockpitInfo(selected), seaSurfaceHeightM: 0 }
         : null,
-    setCockpitSubject(mmsi) {
-      calls.push(['subject', mmsi]);
-      subject = mmsi;
+    setCockpitSubject(id) {
+      calls.push(['subject', id]);
+      subject = id;
       return true;
     },
     // Like the layer, leaves out the ship whose bridge the Cockpit rides.
@@ -75,7 +76,7 @@ function vesselLayer(record) {
       radarQueries.push({ lat, lon, rangeM, maxCount });
       const own = {
         ...NEIGHBOUR,
-        id: record.mmsi,
+        id: record.id,
         latitude: record.lat,
         longitude: record.lon,
       };
@@ -257,7 +258,7 @@ test('entering the bridge hides the vessel and shows bridge readouts', async (t)
   await settle();
   assert.equal(cockpit.active, true);
   assert.equal(cockpit.subjectKind, 'vessel');
-  assert.deepEqual(vessels.calls, [['subject', RECORD.mmsi]]);
+  assert.deepEqual(vessels.calls, [['subject', RECORD.id]]);
   assert.equal(document.body.classList.contains('cockpit-mode'), true);
 
   assert.equal(
@@ -303,7 +304,7 @@ test('exiting the bridge releases the vessel and returns to its map view', async
   assert.equal(cockpit.active, false);
   assert.equal(cockpit.subjectKind, null);
   assert.deepEqual(vessels.calls, [
-    ['subject', RECORD.mmsi],
+    ['subject', RECORD.id],
     ['subject', null],
     ['focus'],
   ]);
@@ -374,7 +375,7 @@ test('tracking an aircraft from the bridge ends it without refocusing the vessel
   assert.equal(viewer.trackedEntity, aircraft, 'the aircraft keeps tracking');
   assert.equal(aircraft.show, true, 'the aircraft was never adopted');
   assert.deepEqual(vessels.calls, [
-    ['subject', RECORD.mmsi],
+    ['subject', RECORD.id],
     ['subject', null],
   ]);
 });
@@ -1474,7 +1475,7 @@ test('a fix the feed keeps re-serving goes on ageing into a stale feed', async (
       effects,
     );
   poll();
-  const record = records.byMmsi.get(RECORD.mmsi);
+  const record = records.byId.get(RECORD.id);
   const { $, cockpit, shots } = fixture(t, { record });
   cockpit.enter();
   await settle();
@@ -1540,7 +1541,12 @@ test("a ship's double-click memory does not carry over to another ship", async (
   heightSensitiveProjection(viewer);
   cockpit.onScenePointerDown(1000);
   // Within the memory another ship is selected, drawn elsewhere.
-  vessels.select({ ...RECORD, mmsi: '211000009', name: 'OTHER' });
+  vessels.select({
+    ...RECORD,
+    id: '211000009',
+    mmsi: '211000009',
+    name: 'OTHER',
+  });
   heightSensitiveProjection(viewer, { x: 900 });
   assert.equal(cockpit.onSceneDoubleClick({ x: 400, y: 300 }, 1250), false);
   assert.equal(cockpit.active, false);

src/ui/cockpitBriefing.js

@@ -164,7 +164,7 @@ export function maybeRefreshRegionalBrief(info) {
     !Number.isFinite(info.longitude)
   )
     return;
-  const subjectId = `${info.layerId || 'aircraft'}:${info.icao24 || info.mmsi || info.noradId || info.registration || info.callsign || 'unknown'}`;
+  const subjectId = `${info.layerId || 'aircraft'}:${info.icao24 || (info.kind === 'vessel' ? info.id : '') || info.noradId || info.registration || info.callsign || 'unknown'}`;
   if (subjectId !== this.regionalBriefSubjectId) {
     this.regionalBriefAbort?.abort();
     this.regionalBriefAbort = null;

src/ui/cockpitCamera.js

@@ -128,7 +128,7 @@ function vesselSurfaceM(info, nowMs, at = info) {
     : 0;
   const scene = this.viewer.scene;
   let read =
-    this.vesselWaterline?.mmsi === info.mmsi ? this.vesselWaterline : null;
+    this.vesselWaterline?.vesselId === info.id ? this.vesselWaterline : null;
   if (
     typeof scene?.sampleHeightMostDetailed === 'function' &&
     (!read || nowMs - read.sampledMs >= VESSEL_WATERLINE_REFRESH_MS)
@@ -138,7 +138,7 @@ function vesselSurfaceM(info, nowMs, at = info) {
     );
     if (!read) {
       read = {
-        mmsi: info.mmsi,
+        vesselId: info.id,
         heightM: loadedWaterlineM(scene, probes, seaM),
         sampledMs: nowMs,
         // Whether a full-detail read has answered for this ship.
@@ -219,7 +219,7 @@ function updateVessel(nowMs) {
     return;
   }
   const info = this.readVesselInfo();
-  if (!info || info.mmsi !== this.subjectId) {
+  if (!info || info.id !== this.subjectId) {
     this.exit({ restoreTracking: false });
     return;
   }

src/ui/cockpitController.js

@@ -139,7 +139,7 @@ export class CockpitViewController {
      */
     this.subjectKind = null;
     /**
-     * The vessel subject's MMSI or the satellite's NORAD id; aircraft are
+     * The vessel subject's id or the satellite's NORAD id; aircraft are
      * identified by trackedEntity.
      */
     this.subjectId = null;

src/ui/cockpitCoordinator.js

@@ -255,7 +255,7 @@ export class CockpitCoordinator {
         : vessel
           ? {
               kind: 'vessel',
-              id: vessel.mmsi,
+              id: vessel.id,
               layerId: vessel.layerId,
               callsign: null,
               name: vessel.name,

src/ui/cockpitInput.js

@@ -83,8 +83,10 @@ export function onScenePointerDown(nowMs = performance.now()) {
     return;
   }
   const at = subjectCanvasPosition.call(this);
-  const mmsi = this.readVesselInfo()?.mmsi ?? null;
-  this.doubleClickStart = at ? { x: at.x, y: at.y, atMs: nowMs, mmsi } : null;
+  const vesselId = this.readVesselInfo()?.id ?? null;
+  this.doubleClickStart = at
+    ? { x: at.x, y: at.y, atMs: nowMs, vesselId }
+    : null;
 }
 
 /**
@@ -111,7 +113,7 @@ export function onSceneDoubleClick(position, nowMs = performance.now()) {
       // The memory is the ship's it was taken for: one followed since (an
       // aircraft, another ship) is hit only where it is drawn.
       this.resolveEntryKind() === 'vessel' &&
-      start.mmsi === (this.readVesselInfo()?.mmsi ?? null) &&
+      start.vesselId === (this.readVesselInfo()?.id ?? null) &&
       doubleClickHitsSubject(position, start));
   if (!hit) return false;
   this.enter();

src/ui/cockpitTrackingController.js

@@ -65,7 +65,12 @@ export function resolveEntryKind() {
 
 export function dispatchCockpitModeChanged(active, info = null) {
   const subjectId = active
-    ? String(info?.icao24 || info?.mmsi || info?.noradId || '')
+    ? String(
+        info?.icao24 ||
+          (info?.kind === 'vessel' ? info.id : '') ||
+          info?.noradId ||
+          '',
+      )
         .trim()
         .toLowerCase() || null
     : null;
@@ -245,7 +250,7 @@ export function enter({ kind = null } = {}) {
   // Each session reads its own water: never a height left from the last.
   this.vesselWaterline = null;
   this.vesselFix = null;
-  this.subjectId = vessel ? info.mmsi : satellite ? info.noradId : null;
+  this.subjectId = vessel ? info.id : satellite ? info.noradId : null;
   this.trackedEntity = entity;
   if (entity) {
     this.trackedEntityWasShown = entity.show;
@@ -255,7 +260,7 @@ export function enter({ kind = null } = {}) {
     this.services.satellitesLayer?.setCockpitSubject?.(info.noradId);
     this.beginOrbital();
   } else {
-    this.services.aisLiveVesselsLayer?.setCockpitSubject?.(info.mmsi);
+    this.services.aisLiveVesselsLayer?.setCockpitSubject?.(info.id);
   }
   // A ship reporting neither heading nor course keeps the camera's own
   // heading: no direction is made up for it.

src/ui/shareFollow.js

@@ -2,6 +2,8 @@ import * as Cesium from 'cesium';
 import { trackedDisplayPositionForCamera } from '../data/trackedCamera.js';
 import {
   SHARE_VIEW_ENTITY_KINDS,
+  SHARE_VIEW_FOLLOW_RANGE_MAX_M,
+  followOffsetFor,
   followOffsetFromEnu,
   followOffsetToEnu,
 } from '../share/follow.js';
@@ -28,17 +30,68 @@ function enuOffset(origin, position) {
   return { east: local.x, north: local.y, up: local.z };
 }
 
+/** Degrees to the share format's 10⁻⁴-degree coordinate precision. */
+const toCoordinate = (radians) =>
+  Math.round(Cesium.Math.toDegrees(radians) * 1e4) / 1e4;
+
 /**
- * The entity the camera follows as `{ kind, id, offset, lastKnown }`, with
- * the camera's offset from it and its displayed position as of `nowMs`; null
- * when the camera follows nothing a share link can name. A selected vessel is
- * not followed (the camera stays where the user puts it), so a link made then
- * keeps its own camera.
+ * The selected vessel as a thing view's subject: its drawn position as the
+ * last-known fix, and the follow offset that puts the derived camera
+ * (followCameraFor) where the camera is now. The offset is computed from the
+ * fix at the format's precision, so the opened link's camera matches this
+ * one to within the offset's whole metres and degrees. Null when the offset
+ * cannot carry the camera (it is not above the vessel's horizon, or its range
+ * is outside 1 m to SHARE_VIEW_FOLLOW_RANGE_MAX_M): the link is then a place
+ * view.
  */
-export function readShareFollowSubject({ viewer, nowMs = Date.now() }) {
+function selectedVesselSubject(cameraPosition, vessel, nowMs) {
+  const id = String(vessel?.id || '');
+  if (!id || !vessel.position) return null;
+  const fixAt = Cesium.Cartographic.fromCartesian(vessel.position);
+  const cameraAt = Cesium.Cartographic.fromCartesian(cameraPosition);
+  if (!fixAt || !cameraAt) return null;
+  const lastKnown = {
+    lat: toCoordinate(fixAt.latitude),
+    lon: toCoordinate(fixAt.longitude),
+    alt: Math.round(fixAt.height),
+    observedAtMs: Number.isFinite(vessel.observedAtMs)
+      ? vessel.observedAtMs
+      : nowMs,
+  };
+  const offset = followOffsetFor(lastKnown, {
+    lat: Cesium.Math.toDegrees(cameraAt.latitude),
+    lon: Cesium.Math.toDegrees(cameraAt.longitude),
+    alt: cameraAt.height,
+  });
+  if (
+    !offset ||
+    !(offset.range >= 1 && offset.range <= SHARE_VIEW_FOLLOW_RANGE_MAX_M)
+  )
+    return null;
+  return { kind: 'vessel', id, offset, lastKnown };
+}
+
+/**
+ * The entity a share link made now names, as `{ kind, id, offset, lastKnown }`:
+ * the entity the camera follows, with the camera's offset from it and its
+ * displayed position as of `nowMs`; else, while the camera follows nothing,
+ * the selected vessel (`readSelectedVessel()`, the vessel layer's
+ * `getSelectedFix()`). A selected vessel is not followed (the camera stays
+ * where the user puts it), so its offset is the one that derives the camera
+ * where it is now. Null when there is nothing a share link can name.
+ */
+export function readShareFollowSubject({
+  viewer,
+  nowMs = Date.now(),
+  readSelectedVessel = null,
+}) {
   const cameraPosition = viewer?.camera?.positionWC;
   if (!cameraPosition) return null;
   const tracked = viewer.trackedEntity;
+  if (!tracked) {
+    const vessel = readSelectedVessel?.() ?? null;
+    return vessel ? selectedVesselSubject(cameraPosition, vessel, nowMs) : null;
+  }
   const trackedId = String(tracked?.gevTrackedId || '');
   const separator = trackedId.indexOf(':');
   if (separator <= 0) return null;

src/ui/shareLinks.test.mjs

@@ -12,6 +12,7 @@ import {
 } from './shareFollow.js';
 import { createDefaultLayerState } from '../data/layerState.js';
 import { parseSharePath, shareLinkUrl } from '../share/shareLinkPath.js';
+import { worldClock } from '../time/worldClock.js';
 import {
   decodeShareView,
   encodeShareView,
@@ -234,7 +235,9 @@ test('a code that fails its check restores nothing and says so', async (t) => {
     (await page.owner.initialRestorePromise).status,
     'not-requested',
   );
-  assert.deepEqual(page.notices, ["This share link can't be opened"]);
+  assert.deepEqual(page.notices, [
+    { message: "This share link can't be opened" },
+  ]);
   // The default start's first address write leaves the bad link behind.
   page.manager._updateHash();
   assert.equal(page.location.pathname, '/');
@@ -334,9 +337,10 @@ test('a thing that is not reporting leaves the view at its last-known fix, with
   await flush();
   assert.equal(page.notices.length, 1);
   assert.match(
-    page.notices[0],
-    /^A1B2C3 isn't reporting now — showing where it was at .+/,
+    page.notices[0].message,
+    /^The shared flight isn't reporting now — showing where it was at .+/,
   );
+  assert.equal(page.notices[0].detail, 'ICAO: A1B2C3');
   // A long link names no fix and keeps the existing notice.
   page.owner._initialShareState = { shareView: null };
   page.owner._handleShareTrackingRestoreStatus({
@@ -345,19 +349,48 @@ test('a thing that is not reporting leaves the view at its last-known fix, with
     label: 'flight',
     classification: 'expired',
   });
-  assert.equal(page.notices[1], 'Shared flight follow expired');
+  assert.deepEqual(page.notices[1], {
+    message: 'Shared flight follow expired',
+  });
 });
 
-test('the not-reporting notice names the id and the time of the fix', () => {
+test('the not-reporting notice is a sentence per kind with the id on a second line', () => {
   const at = new Date(2026, 9, 26, 14, 5).getTime();
+  const flight = sharedFixNotice(
+    { kind: 'aircraft', id: 'a1b2c3' },
+    at,
+    at + 60_000,
+  );
   assert.match(
-    sharedFixNotice({ kind: 'aircraft', id: 'a1b2c3' }, at, at + 60_000),
-    /^A1B2C3 isn't reporting now — showing where it was at .*05/,
+    flight.message,
+    /^The shared flight isn't reporting now — showing where it was at .*05/,
   );
+  assert.equal(flight.detail, 'ICAO: A1B2C3');
+  assert.deepEqual(
+    sharedFixNotice({ kind: 'military_aircraft', id: 'ae01ce' }, null),
+    {
+      message:
+        "The shared military flight isn't reporting now — showing where it was last seen",
+      detail: 'ICAO: AE01CE',
+    },
+  );
+  assert.deepEqual(sharedFixNotice({ kind: 'vessel', id: '366999712' }, null), {
+    message:
+      "The shared vessel isn't reporting now — showing where it was last seen",
+    detail: 'MMSI: 366999712',
+  });
   assert.equal(
-    sharedFixNotice({ kind: 'vessel', id: '366999712' }, null),
-    "366999712 isn't reporting now — showing where it was last seen",
+    sharedFixNotice(
+      { kind: 'vessel', id: '3F2504E0-4F89-11D3-9A0C-0305E82C3301' },
+      null,
+    ).detail,
+    'Vessel UUID: 3f2504e0-4f89-11d3-9a0c-0305e82c3301',
   );
+  assert.deepEqual(sharedFixNotice({ kind: 'satellite', id: '25544' }, null), {
+    message:
+      "The shared satellite isn't reporting now — showing where it was last seen",
+    detail: 'NORAD: 25544',
+  });
 });
 
 test('a shared vessel is selected once the vessel feed has it', async (t) => {
@@ -398,7 +431,11 @@ test('a shared vessel is selected once the vessel feed has it', async (t) => {
     page.runAll();
   }
   assert.equal(await missing, false);
-  assert.match(page.notices.at(-1), /^366999712 isn't reporting now/);
+  assert.match(
+    page.notices.at(-1).message,
+    /^The shared vessel isn't reporting now/,
+  );
+  assert.equal(page.notices.at(-1).detail, 'MMSI: 366999712');
 });
 
 test('the share button links to /share/<code>, following the followed entity', (t) => {
@@ -552,3 +589,174 @@ test('long links and hash navigation are unaffected by a share code start', asyn
   assert.equal(page.restores.length, 2);
   assert.equal(page.restores[1].style, 'normal');
 });
+
+const VESSEL_UUID = '0770e3ca-b896-c307-f499-4f9df2b8f86b';
+const VESSEL_AT = { lat: 51.93012, lon: 4.05118, alt: 46.6 };
+
+/** A camera `offset` from the vessel, as Cesium places it (WGS84). */
+function cameraAround(offset) {
+  const vessel = Cesium.Cartesian3.fromDegrees(
+    VESSEL_AT.lon,
+    VESSEL_AT.lat,
+    VESSEL_AT.alt,
+  );
+  const local = followOffsetToEnu(offset);
+  return {
+    vessel,
+    camera: Cesium.Matrix4.multiplyByPoint(
+      Cesium.Transforms.eastNorthUpToFixedFrame(vessel),
+      new Cesium.Cartesian3(local.east, local.north, local.up),
+      new Cesium.Cartesian3(),
+    ),
+  };
+}
+
+test('a selected vessel is the subject when the camera follows nothing', (t) => {
+  installPage(t, 'https://gev.example/');
+  const offset = { range: 6400, heading: 250, pitch: -28 };
+  const { vessel, camera } = cameraAround(offset);
+  const viewer = fakeViewer();
+  viewer.camera.positionWC = camera;
+  const fixAtMs = Math.floor(NOW_MS / 1000) * 1000 - 90_000;
+  let selected = { id: VESSEL_UUID, position: vessel, observedAtMs: fixAtMs };
+  const readSelectedVessel = () => selected;
+  const subject = readShareFollowSubject({
+    viewer,
+    nowMs: NOW_MS,
+    readSelectedVessel,
+  });
+  assert.equal(subject.kind, 'vessel');
+  assert.equal(subject.id, VESSEL_UUID);
+  // The fix is the vessel's drawn position at the format's precision.
+  assert.deepEqual(subject.lastKnown, {
+    lat: 51.9301,
+    lon: 4.0512,
+    alt: 47,
+    observedAtMs: fixAtMs,
+  });
+  // The inverse of the derived camera, from the user's camera: within the
+  // offset's whole degrees of the camera that placed it.
+  // (The fix is rounded to 10⁻⁴°, about 11 m, before the offset is taken.)
+  assert.ok(Math.abs(subject.offset.range - offset.range) <= 20);
+  assert.ok(Math.abs(subject.offset.heading - offset.heading) <= 1);
+  assert.ok(Math.abs(subject.offset.pitch - offset.pitch) <= 1);
+
+  // The share button's link opens with its camera where this one is.
+  const manager = new ShareLinkManager(viewer);
+  manager.setFollowSubjectProvider(({ nowMs }) =>
+    readShareFollowSubject({ viewer, nowMs, readSelectedVessel }),
+  );
+  const href = manager.buildLink({ nowMs: NOW_MS });
+  const code = parseSharePath(new URL(href).pathname).code;
+  const { state } = decodeShareView(code, { nowMs: NOW_MS });
+  assert.deepEqual(state.view.entity, { kind: 'vessel', id: VESSEL_UUID });
+  assert.equal(state.view.lastKnown.observedAtMs, fixAtMs);
+  const opened = Cesium.Cartesian3.fromDegrees(state.lon, state.lat, state.alt);
+  const missM = Cesium.Cartesian3.distance(opened, camera);
+  // Whole degrees at 6.4 km are at most about 80 m; 10⁻⁴° is about 11 m.
+  assert.ok(missM < 100, `${missM.toFixed(1)} m from the camera`);
+  // The UUID costs 13 bytes more than an ICAO address: 16 against 3.
+  manager.setFollowSubjectProvider(() => ({
+    ...subject,
+    kind: 'aircraft',
+    id: 'a1b2c3',
+  }));
+  const aircraft = parseSharePath(
+    new URL(manager.buildLink({ nowMs: NOW_MS })).pathname,
+  ).code;
+  assert.ok(
+    code.length - aircraft.length <= 18,
+    `${code.length} against ${aircraft.length} characters`,
+  );
+  manager.destroy();
+
+  // A camera below the vessel's horizon cannot be carried: a place view.
+  viewer.camera.positionWC = Cesium.Cartesian3.fromDegrees(4.0512, 54, 900);
+  assert.equal(
+    readShareFollowSubject({ viewer, nowMs: NOW_MS, readSelectedVessel }),
+    null,
+  );
+  // Nor can one at the vessel.
+  viewer.camera.positionWC = vessel;
+  assert.equal(
+    readShareFollowSubject({ viewer, nowMs: NOW_MS, readSelectedVessel }),
+    null,
+  );
+  // With nothing selected there is no subject.
+  viewer.camera.positionWC = camera;
+  selected = null;
+  assert.equal(
+    readShareFollowSubject({ viewer, nowMs: NOW_MS, readSelectedVessel }),
+    null,
+  );
+});
+
+test('a followed aircraft or satellite keeps priority over a selected vessel', () => {
+  const { vessel, camera } = cameraAround({
+    range: 2400,
+    heading: 30,
+    pitch: -20,
+  });
+  const readSelectedVessel = () => ({
+    id: VESSEL_UUID,
+    position: vessel,
+    observedAtMs: NOW_MS,
+  });
+  const viewer = {
+    camera: { positionWC: camera },
+    clock: { currentTime: Cesium.JulianDate.now() },
+    trackedEntity: {
+      gevTrackedId: 'satellites:25544',
+      gevDisplayPosition: () => vessel,
+    },
+  };
+  const subject = readShareFollowSubject({ viewer, readSelectedVessel });
+  assert.equal(subject.kind, 'satellite');
+  // A followed entity the share format cannot name is still followed: the
+  // link is a place view, not the selected vessel.
+  viewer.trackedEntity.gevTrackedId = 'local-adsb:abc';
+  assert.equal(readShareFollowSubject({ viewer, readSelectedVessel }), null);
+});
+
+test('a link to a UUID vessel at a world time selects it once its snapshot has it', async (t) => {
+  t.after(() => worldClock.goLive());
+  const worldTime = Math.floor((NOW_MS - 3_600_000) / 1000) * 1000;
+  const code = encodeShareView({
+    view: {
+      kind: 'thing',
+      entity: { kind: 'vessel', id: VESSEL_UUID },
+      offset: { range: 3200, heading: 20, pitch: -30 },
+      lastKnown: { ...VESSEL_AT, alt: 47, observedAtMs: worldTime },
+    },
+    sharedAtMs: Math.floor(NOW_MS / 1000) * 1000,
+    worldTime,
+  });
+  const page = openPage(t, `http://localhost/share/${code}`);
+  // The link opens paused at its world time.
+  assert.equal(worldClock.isLive(), false);
+  assert.equal(worldClock.now(), worldTime);
+  // The vessel layer: its records are the snapshot at the clock's time, which
+  // arrives a moment after the layer turns on.
+  const records = new Set();
+  const selected = [];
+  page.owner._dataManager = {
+    layers: new Map([
+      [
+        'ais-live-vessels',
+        {
+          module: {
+            hasContact: (id) => (records.size ? records.has(id) : null),
+            selectById: (id) => records.has(id) && selected.push(id) > 0,
+          },
+        },
+      ],
+    ]),
+  };
+  await restore(page);
+  assert.deepEqual(selected, []);
+  if (worldClock.now() === worldTime) records.add(VESSEL_UUID);
+  page.runAll();
+  await flush();
+  assert.deepEqual(selected, [VESSEL_UUID]);
+  assert.deepEqual(page.notices, []);
+});

src/ui/shareRestoration.js

@@ -70,34 +70,88 @@ export function shareTrackingRestoreNotice(result) {
       : t('Shared {subject} is unavailable', { subject });
 }
 
+// The not-reporting notice, one ready-made sentence per shared entity kind
+// (SHARE_VIEW_ENTITY_KINDS) for the same reason as SHARE_RESTORE_NOTICES.
+const SHARED_FIX_NOTICES = Object.freeze({
+  aircraft: Object.freeze({
+    lastSeen: msg(
+      "The shared flight isn't reporting now — showing where it was last seen",
+    ),
+    at: msg(
+      "The shared flight isn't reporting now — showing where it was at {time}",
+    ),
+  }),
+  military_aircraft: Object.freeze({
+    lastSeen: msg(
+      "The shared military flight isn't reporting now — showing where it was last seen",
+    ),
+    at: msg(
+      "The shared military flight isn't reporting now — showing where it was at {time}",
+    ),
+  }),
+  vessel: Object.freeze({
+    lastSeen: msg(
+      "The shared vessel isn't reporting now — showing where it was last seen",
+    ),
+    at: msg(
+      "The shared vessel isn't reporting now — showing where it was at {time}",
+    ),
+  }),
+  satellite: Object.freeze({
+    lastSeen: msg(
+      "The shared satellite isn't reporting now — showing where it was last seen",
+    ),
+    at: msg(
+      "The shared satellite isn't reporting now — showing where it was at {time}",
+    ),
+  }),
+});
+
+// The second line names the entity by the id the link carries.
+function sharedFixDetail(entity) {
+  const id = String(entity.id);
+  switch (entity.kind) {
+    case 'aircraft':
+    case 'military_aircraft':
+      // ICAO addresses read as they are written on the aircraft: upper case.
+      return t('ICAO: {id}', { id: id.toUpperCase() });
+    case 'satellite':
+      return t('NORAD: {id}', { id });
+    case 'vessel':
+      return /^\d+$/.test(id)
+        ? t('MMSI: {id}', { id })
+        : t('Vessel UUID: {id}', { id: id.toLowerCase() });
+    default:
+      return id;
+  }
+}
+
 /**
  * The notice for a shared entity that is not reporting: the view shows where
- * it was when the link was made.
+ * it was when the link was made. The sentence is the notice; the entity's id
+ * goes on a second line under it.
  * @param {{kind: string, id: string}} entity
  * @param {number|null} observedAtMs
  * @param {number} [nowMs]
- * @returns {string}
+ * @returns {{message: string, detail: string}}
  */
 export function sharedFixNotice(entity, observedAtMs, nowMs = Date.now()) {
-  // ICAO addresses read as they are written on the aircraft: upper case.
-  const id =
-    ENTITY_BY_KIND.get(entity.kind)?.idForm === 'hex24'
-      ? String(entity.id).toUpperCase()
-      : String(entity.id);
+  const detail = sharedFixDetail(entity);
+  const notices = SHARED_FIX_NOTICES[entity.kind];
+  if (!notices)
+    return {
+      message: t('Shared {subject} is unavailable', { subject: t('entity') }),
+      detail,
+    };
   if (!Number.isFinite(observedAtMs))
-    return t("{id} isn't reporting now — showing where it was last seen", {
-      id,
-    });
+    return { message: t(notices.lastSeen), detail };
   const time = formatDate(
     observedAtMs,
     nowMs - observedAtMs < DAY_MS
       ? { hour: '2-digit', minute: '2-digit' }
       : { month: 'short', day: 'numeric', hour: '2-digit', minute: '2-digit' },
   );
-  return t("{id} isn't reporting now — showing where it was at {time}", {
-    id,
-    time,
-  });
+  return { message: t(notices.at, { time }), detail };
 }
 
 /** Own initial share restoration, durable layer state and restoration notices. */
@@ -181,7 +235,7 @@ export class ShareRestoration {
       this.syncShareState();
       if (this.shareLinkManager?.rejectedShareCode)
         this._presentAfterStartupCover(
-          t("This share link can't be opened"),
+          { message: t("This share link can't be opened") },
           ++this._shareTrackingNoticeGeneration,
         );
     }
@@ -411,7 +465,7 @@ export class ShareRestoration {
     this._presentAfterStartupCover(
       view.lastKnown
         ? sharedFixNotice(view.entity, view.lastKnown.observedAtMs)
-        : t('Shared vessel is unavailable'),
+        : { message: t('Shared vessel is unavailable') },
       ++this._shareTrackingNoticeGeneration,
     );
     return false;
@@ -505,26 +559,36 @@ export class ShareRestoration {
     // A share link that knows where the entity was says so; the view is
     // already there.
     const fix = this._sharedThingFor(result)?.lastKnown;
-    const message = fix
+    const notice = fix
       ? sharedFixNotice(
           this._initialShareState.shareView.entity,
           fix.observedAtMs,
         )
-      : shareTrackingRestoreNotice(result);
+      : { message: shareTrackingRestoreNotice(result) };
     if (this._resolveInitialShareRestore) {
       void this.initialRestorePromise.then(() =>
-        this._presentAfterStartupCover(message, noticeGeneration),
+        this._presentAfterStartupCover(notice, noticeGeneration),
       );
       return;
     }
-    this._presentAfterStartupCover(message, noticeGeneration);
+    this._presentAfterStartupCover(notice, noticeGeneration);
   }
 
   /**
    * Show a status notice once the start-up cover is gone, unless a newer
-   * notice (generation) has taken its place.
+   * notice (generation) has taken its place. A notice with a detail line is
+   * a last-known one: the sentence over the entity's id.
+   * @param {{message: string, detail?: string}} notice
+   * @param {number} noticeGeneration
    */
-  _presentAfterStartupCover(message, noticeGeneration) {
+  _presentAfterStartupCover(notice, noticeGeneration) {
+    const show = () =>
+      notice.detail
+        ? this.showStatus(notice.message, {
+            state: 'last-known',
+            detail: notice.detail,
+          })
+        : this.showStatus(notice.message);
     const showAfterStartupCover = () => {
       this._lifetime.frame(() => {
         if (
@@ -540,7 +604,7 @@ export class ShareRestoration {
           !startupCover ||
           getComputedStyle(startupCover).visibility === 'hidden'
         ) {
-          this.showStatus(message);
+          show();
           return;
         }
         let fallbackTimer = null;
@@ -555,7 +619,7 @@ export class ShareRestoration {
               this._disposed,
             )
           )
-            this.showStatus(message);
+            show();
         };
         removeStartupListener = this._lifetime.listen(
           startupCover,

src/ui/styles/status.css

@@ -166,6 +166,24 @@ html:not([lang='en']) #global-loading-detail {
 #global-loading-status[data-state='cancelled'] #global-loading-detail {
   color: #ffd488;
 }
+/* A last-known notice is a sentence with the entity's id on a second line;
+   the id is shown whole (a vessel UUID is 36 characters). */
+#global-loading-status[data-state='last-known'] {
+  flex-direction: column;
+  gap: 3px;
+  border-color: rgba(255, 212, 136, 0.55);
+  text-align: center;
+}
+#global-loading-status[data-state='last-known'] #global-loading-label {
+  color: #ffd488;
+}
+#global-loading-status[data-state='last-known'] #global-loading-detail {
+  max-width: none;
+  color: rgba(255, 228, 176, 0.82);
+  letter-spacing: 1.2px;
+  text-align: center;
+  text-transform: none;
+}
 #global-loading-status[data-state='acquiring'] {
   border-color: rgba(0, 212, 255, 0.42);
   box-shadow:

src/voice/gevActions.js

@@ -2824,7 +2824,7 @@ async function trackEntity(
       () => {
         let trackedOk = false;
         if (family.kind === 'vessel') {
-          trackedOk = !!module.selectById?.(found.mmsi);
+          trackedOk = !!module.selectById?.(found.id ?? found.mmsi);
           flyToLandmark(viewer, found.latitude, found.longitude, {
             range: 6000,
             pitch: -45,
@@ -4003,8 +4003,13 @@ function locateLayerEntity(dataManager, { layerId, id, lat, lon }) {
         ?.module?.getAnalystRecords?.()
         .filter(
           (item) =>
-            String(item.icao24 ?? item.mmsi ?? item.noradId ?? item.id) ===
-            String(id),
+            String(
+              item.icao24 ??
+                item.vesselId ??
+                item.mmsi ??
+                item.noradId ??
+                item.id,
+            ) === String(id),
         ) || [];
     // Bikeshare uses station names as IDs: retain the coordinate identity
     // even if a namesake disappears. Moving records use their fresh fix.
@@ -5344,6 +5349,7 @@ function cameraViewBox(viewer) {
 /** Identity fields every compact analyst item keeps when present. */
 const ANALYST_IDENTITY_FIELDS = Object.freeze([
   'icao24',
+  'vesselId',
   'mmsi',
   'registration',
   'label',
@@ -5361,6 +5367,7 @@ const ANALYST_CANONICAL_FIELDS = new Set([
   'layerKey',
   'id',
   'icao24',
+  'vesselId',
   'mmsi',
   'noradId',
   'registration',
@@ -5373,7 +5380,7 @@ const ANALYST_CANONICAL_FIELDS = new Set([
  * follow-up can fly to it), distance, and that layer's manifest fields with
  * times as ISO text. The full record set stays engine-side for follow-ups.
  *
- * `icao24`/`mmsi` ride along because the tool instructions tell the model to
+ * `icao24`/`vesselId`/`mmsi` ride along because the tool instructions tell the model to
  * hand this result straight to track_entity, and `id` is a DISPLAY label
  * (callsign, else registration, else hex). A callsign-less contact therefore
  * handed track_entity a tail number the lookup could not resolve, and the

src/voice/pointAndAskReview.test.mjs

@@ -245,6 +245,31 @@ test('P2-7: duplicate callsigns and names resolve by canonical identity', () =>
   );
 });
 
+test('vessels sharing an MMSI resolve by their vessel id', () => {
+  const referents = createReferentRegistry();
+  referents.recordResult('analyst_query', {
+    ok: true,
+    items: ['hull-a', 'hull-b'].map((vesselId) => ({
+      layerKey: 'ais-live-vessels',
+      id: 'EVER GIVEN',
+      vesselId,
+      mmsi: '353136000',
+      name: 'EVER GIVEN',
+    })),
+  });
+  assert.deepEqual(
+    [1, 2].map(
+      (n) =>
+        resolveDeicticArgs(
+          'track_entity',
+          { query: 'x', referent: n },
+          { referents },
+        ).args.query,
+    ),
+    ['hull-a', 'hull-b'],
+  );
+});
+
 test('P1-1: a result from before the last clear cannot repopulate the registry', () => {
   const referents = createReferentRegistry();
   const since = referents.generation();

src/voice/referents.js

@@ -23,10 +23,17 @@ function finite(value) {
 
 function normalize(entry, index) {
   if (!entry || typeof entry !== 'object') return null;
-  // Identity is the canonical key (transponder hex, MMSI, NORAD id); a
+  // Identity is the canonical key (transponder hex, vessel id, NORAD id); a
   // display `id` such as a callsign is only a label, and two contacts can
-  // share one.
-  const id = entry.icao24 ?? entry.mmsi ?? entry.noradId ?? entry.id ?? null;
+  // share one. Vessels can share an MMSI too, so a vessel's key is its
+  // `vesselId` when the row names one.
+  const id =
+    entry.icao24 ??
+    entry.vesselId ??
+    entry.mmsi ??
+    entry.noradId ??
+    entry.id ??
+    null;
   const label = String(
     entry.label ?? entry.callsign ?? entry.name ?? entry.id ?? id ?? '',
   ).trim();

src/voice/speech.js

@@ -501,7 +501,7 @@ function frameOverhead(result) {
     .filter((entry) => entry?.label || entry?.id)
     .map((entry, index) => ({
       n: index + 1,
-      id: entry.icao24 || entry.mmsi || entry.id || null,
+      id: entry.icao24 || entry.id || entry.mmsi || null,
       label: spokenLabel(entry.label || entry.id),
       layerId: result.layerId,
     }));