[fix](trx-frontend-http): stop the decode history replay giving up at 20s

Reloading a second time sometimes showed history the first load did not,
and the safety valve is why: it called one function that both released
the buffered live decodes and tore the history worker down, so any load
where the replay had not finished inside twenty seconds — a large
backlog, a cold cache, a slow link — dropped whatever had not arrived,
without a word.  A reload got another go at it, and the second one is
faster because everything is cached by then.

Those are two separate things now.  At the timeout the live decodes are
released so the panels are not held back, the replay carries on, and the
progress says so.  The fallback's error path retries once and then says
"Decode history unavailable" rather than leaving the operator to guess
whether there was anything to see.

The progress is no longer a scrim.  It was fixed to the whole viewport
with a wash over the page — the waterfall, the decode panels, all of it —
for the length of the replay, which is exactly when there is something
worth watching.  It is a corner card with a bar: indeterminate while the
payload is on the wire, then filling as N of M messages replay.

None of this was reachable from a test.  /decode/history answers in CBOR
and the worker reads the body as CBOR unconditionally, but the fixture
served JSON, so every browser run had been exercising the client's retry
path and never its history path.  It encodes CBOR now, including the
64-bit form the millisecond timestamps need, and decode-flow serves 1200
records and holds the client to restoring all of them on the first load,
showing progress while it does, and never covering the page with it.

Signed-off-by: Stan Grams <sjg@haxx.space>

src/trx-client/trx-frontend/trx-frontend-http/assets/web/generated/app.js

@@ -1689,7 +1689,24 @@ function estimateNoiseFloorDb(bins) {
 
 // src/plugin-loader.ts
 var pluginGroups = {
-  "digital-modes": ["/ft8.js", "/ft4.js", "/ft2.js", "/wspr.js", "/cw.js", "/background-decode.js", "/sat.js", "/wefax.js"],
+  // AIS, VDES and the two APRS decoders have panels on this tab, so they load
+  // with it. They used to come only with the map group, which left their
+  // sub-tabs empty — decodes queueing in the runtime — until something opened
+  // the Map tab. Their map calls are optional, so map-core stays lazy.
+  "digital-modes": [
+    "/ft8.js",
+    "/ft4.js",
+    "/ft2.js",
+    "/wspr.js",
+    "/cw.js",
+    "/background-decode.js",
+    "/sat.js",
+    "/wefax.js",
+    "/ais.js",
+    "/vdes.js",
+    "/aprs.js",
+    "/hf-aprs.js"
+  ],
   "map-data": ["/map-core.js", "/ais.js", "/vdes.js", "/aprs.js", "/hf-aprs.js"],
   map: ["/map-core.js", "/ais.js", "/vdes.js", "/aprs.js", "/hf-aprs.js", "/sat.js", "/sat-scheduler.js"],
   statistics: ["/map-core.js"],
@@ -2048,6 +2065,7 @@ var loadingSub = requiredElement("loading-sub");
 var decodeHistoryOverlayEl = document.getElementById("decode-history-overlay");
 var decodeHistoryOverlayTitleEl = document.getElementById("decode-history-overlay-title");
 var decodeHistoryOverlaySubEl = document.getElementById("decode-history-overlay-sub");
+var decodeHistoryProgressBarEl = document.getElementById("decode-history-progress-bar");
 var connLostOverlayEl = document.getElementById("conn-lost-overlay");
 var connLostOverlayTitleEl = document.getElementById("conn-lost-overlay-title");
 var connLostOverlaySubEl = document.getElementById("conn-lost-overlay-sub");
@@ -2197,10 +2215,19 @@ function syncTopBarAccess() {
   }
 }
 var overviewDrawPending = false;
-function setDecodeHistoryOverlayVisible(visible, title = "", sub = "") {
+function setDecodeHistoryOverlayVisible(visible, title = "", sub = "", fraction = null) {
   if (!decodeHistoryOverlayEl) return;
   if (title && decodeHistoryOverlayTitleEl) decodeHistoryOverlayTitleEl.textContent = title;
   if (decodeHistoryOverlaySubEl) decodeHistoryOverlaySubEl.textContent = sub || "";
+  if (decodeHistoryProgressBarEl) {
+    if (fraction == null) {
+      decodeHistoryOverlayEl.dataset.phase = "fetching";
+      decodeHistoryProgressBarEl.style.width = "";
+    } else {
+      delete decodeHistoryOverlayEl.dataset.phase;
+      decodeHistoryProgressBarEl.style.width = `${Math.round(Math.max(0, Math.min(1, fraction)) * 100)}%`;
+    }
+  }
   decodeHistoryOverlayEl.classList.toggle("is-hidden", !visible);
 }
 function setConnLostOverlay(visible, title = "Connection lost", sub = "Retrying…", fullscreen = false) {
@@ -7502,16 +7529,15 @@ function connectDecode() {
   let historySettled = false;
   let historyWorkerDone = false;
   let historyFallbackStarted = false;
+  let historyRetried = false;
   let historyBatchDrainScheduled = false;
   let historyTotal = 0;
   let historyProcessed = 0;
   const historyGroupQueue = [];
   const liveBuffer = [];
-  function flushLiveBuffer() {
+  function releaseLiveBuffer() {
+    if (historySettled) return;
     historySettled = true;
-    terminateDecodeHistoryWorker();
-    setDecodeHistoryReplayActive(false);
-    setDecodeHistoryOverlayVisible(false);
     for (const msg of liveBuffer) {
       try {
         dispatchDecodeMessage(msg);
@@ -7520,19 +7546,23 @@ function connectDecode() {
     }
     liveBuffer.length = 0;
   }
+  function finishHistoryReplay() {
+    clearTimeout(historyTimeout);
+    releaseLiveBuffer();
+    terminateDecodeHistoryWorker();
+    setDecodeHistoryReplayActive(false);
+    setDecodeHistoryOverlayVisible(false);
+  }
   function updateHistoryReplayOverlay() {
     setDecodeHistoryOverlayVisible(
       true,
       "Loading decode history…",
-      `Replaying ${historyProcessed} / ${historyTotal} decoded messages`
+      `Replaying ${historyProcessed} / ${historyTotal} decoded messages`,
+      historyTotal > 0 ? historyProcessed / historyTotal : null
     );
   }
   function maybeFinishHistoryReplay() {
-    if (historySettled) return;
+    if (historyWorkerDone && historyGroupQueue.length === 0) finishHistoryReplay();
-    if (historyWorkerDone && historyGroupQueue.length === 0) {
-      clearTimeout(historyTimeout);
-      flushLiveBuffer();
-    }
   }
   function pumpDecodeHistoryGroupQueue() {
     historyBatchDrainScheduled = false;
@@ -7586,17 +7616,25 @@ function connectDecode() {
     if (historyFallbackStarted || historySettled) return;
     historyFallbackStarted = true;
     loadDecodeHistoryOnMainThread((groups) => {
-      clearTimeout(historyTimeout);
       const total = totalDecodeHistoryMessages(groups);
       if (total > 0) {
         enqueueDecodeHistoryGroups(groups);
       } else {
-        flushLiveBuffer();
+        finishHistoryReplay();
       }
     }, (err) => {
       console.error("Decode history fallback failed", err);
-      clearTimeout(historyTimeout);
+      if (historyRetried) {
-      flushLiveBuffer();
+        showHint("Decode history unavailable", 3e3);
+        finishHistoryReplay();
+        return;
+      }
+      historyRetried = true;
+      historyFallbackStarted = false;
+      setDecodeHistoryOverlayVisible(true, "Loading decode history…", "Retrying");
+      setTimeout(() => {
+        startDecodeHistoryFallback();
+      }, 2e3);
     });
   }
   function startDecodeHistoryWorkerReplay() {
@@ -7657,10 +7695,9 @@ function connectDecode() {
     return true;
   }
   const historyTimeout = setTimeout(() => {
-    if (!historySettled) {
+    if (historySettled) return;
-      terminateDecodeHistoryWorker();
+    releaseLiveBuffer();
-      flushLiveBuffer();
+    setDecodeHistoryOverlayVisible(true, "Loading decode history…", "Still loading — live decodes are showing");
-    }
   }, 2e4);
   setDecodeHistoryOverlayVisible(true, "Loading decode history…", "Fetching recent decodes from the client buffer");
   decodeSource = new EventSource("/decode");
@@ -7682,7 +7719,7 @@ function connectDecode() {
     const wasClosed = source.readyState === 2;
     source.close();
     terminateDecodeHistoryWorker();
-    if (!historySettled) flushLiveBuffer();
+    if (!historySettled) releaseLiveBuffer();
     if (wasClosed) {
       updateDecodeStatus("Decode not available (check client audio config)");
       setTimeout(connectDecode, 1e4);

src/trx-client/trx-frontend/trx-frontend-http/assets/web/index.html

@@ -1660,11 +1660,12 @@ SPDX-License-Identifier: GPL-2.0-or-later
       <div class="shortcut-overlay-hint">Press <kbd>F1</kbd> or <kbd>Esc</kbd> to close</div>
     </div>
   </div>
-  <div id="decode-history-overlay" class="decode-history-overlay is-hidden" aria-live="polite" aria-atomic="true">
+  <div id="decode-history-overlay" class="history-progress is-hidden" role="status" aria-live="polite" aria-atomic="true">
-    <div class="decode-history-overlay-card">
+    <div class="history-progress-text">
-      <div id="decode-history-overlay-title" class="decode-history-overlay-title">Loading decode history…</div>
+      <span id="decode-history-overlay-title" class="history-progress-title">Loading decode history…</span>
-      <div id="decode-history-overlay-sub" class="decode-history-overlay-sub">Preparing recent decodes for the UI</div>
+      <span id="decode-history-overlay-sub" class="history-progress-sub">Preparing recent decodes for the UI</span>
     </div>
+    <span class="history-progress-track"><span id="decode-history-progress-bar" class="history-progress-bar"></span></span>
   </div>
   <script defer src="/vendor/opus-decoder-0.7.11.min.js" charset="UTF-8"></script>
   <script defer src="/vendor/leaflet.js"></script>

src/trx-client/trx-frontend/trx-frontend-http/assets/web/style.css

@@ -2209,6 +2209,74 @@ small { color: var(--text-muted); }
   color: var(--text-muted);
 }
 
+/* Decode history loads in the corner, not over the page.  It was a full-screen
+   scrim: the operator could not read the waterfall, the decode panels or
+   anything else while a large history replayed, and the replay is exactly when
+   there is something to watch. */
+.history-progress {
+  position: fixed;
+  left: var(--space-4);
+  bottom: var(--space-4);
+  z-index: 120;
+  display: flex;
+  flex-direction: column;
+  gap: 0.4rem;
+  width: min(20rem, calc(100vw - 2rem));
+  padding: 0.6rem 0.75rem 0.7rem;
+  border: 1px solid color-mix(in srgb, var(--border-light) 70%, transparent);
+  border-radius: var(--radius-md);
+  background: color-mix(in srgb, var(--card-bg) 94%, transparent);
+  box-shadow: 0 10px 24px color-mix(in srgb, var(--bg) 35%, transparent);
+  pointer-events: none;
+  transition: opacity var(--dur-base) var(--ease-standard),
+              visibility var(--dur-base) var(--ease-standard);
+}
+.history-progress.is-hidden {
+  opacity: 0;
+  visibility: hidden;
+}
+.history-progress-text {
+  display: flex;
+  flex-direction: column;
+  gap: 0.1rem;
+  min-width: 0;
+}
+.history-progress-title {
+  font-size: var(--fs-xs);
+  font-weight: 700;
+  color: var(--text-heading);
+}
+.history-progress-sub {
+  font-size: var(--fs-xs);
+  color: var(--text-muted);
+  font-variant-numeric: tabular-nums;
+}
+.history-progress-track {
+  height: 0.28rem;
+  border-radius: var(--radius-pill);
+  background: color-mix(in srgb, var(--border-light) 45%, transparent);
+  overflow: hidden;
+}
+.history-progress-bar {
+  display: block;
+  width: 0%;
+  height: 100%;
+  border-radius: inherit;
+  background: var(--accent-green);
+  transition: width var(--dur-base) var(--ease-out);
+}
+/* Indeterminate while the payload is still on the wire. */
+.history-progress[data-phase="fetching"] .history-progress-bar {
+  width: 35%;
+  animation: trx-history-sweep 1.1s var(--ease-standard) infinite;
+}
+@keyframes trx-history-sweep {
+  0%   { transform: translateX(-100%); }
+  100% { transform: translateX(285%); }
+}
+@media (max-width: 760px) {
+  .history-progress { bottom: calc(5.9rem + env(safe-area-inset-bottom)); }
+}
 .decode-history-overlay {
   position: fixed;
   inset: 0;

src/trx-client/trx-frontend/trx-frontend-http/frontend/package.json

@@ -12,7 +12,7 @@
     "typecheck": "tsc --project tsconfig.json && tsc --project tsconfig.worker.json",
     "lint": "eslint \"src/**/*.ts\" \"tests/**/*.mjs\" build.mjs --no-error-on-unmatched-pattern",
     "test": "node --test tests/*.test.mjs",
-    "test:browser": "node tests/browser-smoke.mjs && node tests/spectrum-layout.mjs",
+    "test:browser": "node tests/browser-smoke.mjs && node tests/spectrum-layout.mjs && node tests/decode-flow.mjs",
     "verify-generated": "npm run generate-types && npm run build && git diff --exit-code -- ../assets/web/generated src/api/generated.ts"
   },
   "devDependencies": {

src/trx-client/trx-frontend/trx-frontend-http/frontend/src/app.ts

@@ -712,6 +712,7 @@ const loadingSub = requiredElement("loading-sub");
 const decodeHistoryOverlayEl = document.getElementById("decode-history-overlay");
 const decodeHistoryOverlayTitleEl = document.getElementById("decode-history-overlay-title");
 const decodeHistoryOverlaySubEl = document.getElementById("decode-history-overlay-sub");
+const decodeHistoryProgressBarEl = document.getElementById("decode-history-progress-bar");
 const connLostOverlayEl = document.getElementById("conn-lost-overlay");
 const connLostOverlayTitleEl = document.getElementById("conn-lost-overlay-title");
 const connLostOverlaySubEl = document.getElementById("conn-lost-overlay-sub");
@@ -880,10 +881,29 @@ function syncTopBarAccess() {
 }
 
 let overviewDrawPending = false;
-function setDecodeHistoryOverlayVisible(visible: boolean, title = "", sub = "") {
+// Progress, in the corner. This used to dim the whole page behind a scrim,
+// which hid the waterfall and the decode panels for as long as the replay ran
+// — and a replay only happens when there is a backlog worth watching arrive.
+// `fraction` null leaves the bar indeterminate, for the part where the payload
+// is still on the wire and there is nothing to count yet.
+function setDecodeHistoryOverlayVisible(
+  visible: boolean,
+  title = "",
+  sub = "",
+  fraction: number | null = null,
+) {
   if (!decodeHistoryOverlayEl) return;
   if (title && decodeHistoryOverlayTitleEl) decodeHistoryOverlayTitleEl.textContent = title;
   if (decodeHistoryOverlaySubEl) decodeHistoryOverlaySubEl.textContent = sub || "";
+  if (decodeHistoryProgressBarEl) {
+    if (fraction == null) {
+      decodeHistoryOverlayEl.dataset.phase = "fetching";
+      decodeHistoryProgressBarEl.style.width = "";
+    } else {
+      delete decodeHistoryOverlayEl.dataset.phase;
+      decodeHistoryProgressBarEl.style.width = `${Math.round(Math.max(0, Math.min(1, fraction)) * 100)}%`;
+    }
+  }
   decodeHistoryOverlayEl.classList.toggle("is-hidden", !visible);
 }
 
@@ -6494,36 +6514,44 @@ function connectDecode() {
   let historySettled = false;
   let historyWorkerDone = false;
   let historyFallbackStarted = false;
+  let historyRetried = false;
   let historyBatchDrainScheduled = false;
   let historyTotal = 0;
   let historyProcessed = 0;
   const historyGroupQueue: DecodeHistoryGroup[] = [];
   const liveBuffer: DecodeMessage[] = [];
-  function flushLiveBuffer() {
+  // Live decodes wait behind the history so the panels stay in order. Letting
+  // them through is not the same as being finished, and conflating the two is
+  // what made a slow history disappear: the safety valve released the buffer
+  // and tore the worker down with it, so whatever had not arrived never did.
+  function releaseLiveBuffer() {
+    if (historySettled) return;
     historySettled = true;
-    terminateDecodeHistoryWorker();
-    setDecodeHistoryReplayActive(false);
-    setDecodeHistoryOverlayVisible(false);
     for (const msg of liveBuffer) {
       try { dispatchDecodeMessage(msg); } catch (_) {}
     }
     liveBuffer.length = 0;
   }
 
+  function finishHistoryReplay() {
+    clearTimeout(historyTimeout);
+    releaseLiveBuffer();
+    terminateDecodeHistoryWorker();
+    setDecodeHistoryReplayActive(false);
+    setDecodeHistoryOverlayVisible(false);
+  }
+
   function updateHistoryReplayOverlay() {
     setDecodeHistoryOverlayVisible(
       true,
       "Loading decode history…",
-      `Replaying ${historyProcessed} / ${historyTotal} decoded messages`
+      `Replaying ${historyProcessed} / ${historyTotal} decoded messages`,
+      historyTotal > 0 ? historyProcessed / historyTotal : null,
     );
   }
 
   function maybeFinishHistoryReplay() {
-    if (historySettled) return;
+    if (historyWorkerDone && historyGroupQueue.length === 0) finishHistoryReplay();
-    if (historyWorkerDone && historyGroupQueue.length === 0) {
-      clearTimeout(historyTimeout);
-      flushLiveBuffer();
-    }
   }
 
   function pumpDecodeHistoryGroupQueue() {
@@ -6585,17 +6613,26 @@ function connectDecode() {
     if (historyFallbackStarted || historySettled) return;
     historyFallbackStarted = true;
     loadDecodeHistoryOnMainThread((groups) => {
-      clearTimeout(historyTimeout);
       const total = totalDecodeHistoryMessages(groups);
       if (total > 0) {
         enqueueDecodeHistoryGroups(groups);
       } else {
-        flushLiveBuffer();
+        finishHistoryReplay();
       }
     }, (err: unknown) => {
       console.error("Decode history fallback failed", err);
-      clearTimeout(historyTimeout);
+      // One retry, then say so. Failing silently here is why the history
-      flushLiveBuffer();
+      // sometimes only turned up on a second reload: nothing asked again and
+      // nothing said anything was missing.
+      if (historyRetried) {
+        showHint("Decode history unavailable", 3000);
+        finishHistoryReplay();
+        return;
+      }
+      historyRetried = true;
+      historyFallbackStarted = false;
+      setDecodeHistoryOverlayVisible(true, "Loading decode history…", "Retrying");
+      setTimeout(() => { startDecodeHistoryFallback(); }, 2000);
     });
   }
 
@@ -6664,12 +6701,13 @@ function connectDecode() {
     return true;
   }
 
-  // Safety valve: if the history fetch hangs, unblock after 20 s.
+  // Safety valve: after 20 s, stop holding live decodes back — but keep
+  // loading. The history is what the operator is waiting for, and dropping it
+  // on the floor at the timeout is not something they can even see happen.
   const historyTimeout = setTimeout(() => {
-    if (!historySettled) {
+    if (historySettled) return;
-      terminateDecodeHistoryWorker();
+    releaseLiveBuffer();
-      flushLiveBuffer();
+    setDecodeHistoryOverlayVisible(true, "Loading decode history…", "Still loading — live decodes are showing");
-    }
   }, 20000);
   setDecodeHistoryOverlayVisible(true, "Loading decode history…", "Fetching recent decodes from the client buffer");
 
@@ -6692,7 +6730,7 @@ function connectDecode() {
     const wasClosed = source.readyState === 2;
     source.close();
     terminateDecodeHistoryWorker();
-    if (!historySettled) flushLiveBuffer();
+    if (!historySettled) releaseLiveBuffer();
     if (wasClosed) {
       updateDecodeStatus("Decode not available (check client audio config)");
       setTimeout(connectDecode, 10000);

src/trx-client/trx-frontend/trx-frontend-http/frontend/src/plugin-loader.ts

@@ -5,7 +5,14 @@
 type PluginGroup = "digital-modes" | "map-data" | "map" | "statistics" | "bookmarks" | "recorder" | "settings";
 
 const pluginGroups: Readonly<Record<PluginGroup, readonly string[]>> = {
-  "digital-modes": ["/ft8.js", "/ft4.js", "/ft2.js", "/wspr.js", "/cw.js", "/background-decode.js", "/sat.js", "/wefax.js"],
+  // AIS, VDES and the two APRS decoders have panels on this tab, so they load
+  // with it. They used to come only with the map group, which left their
+  // sub-tabs empty — decodes queueing in the runtime — until something opened
+  // the Map tab. Their map calls are optional, so map-core stays lazy.
+  "digital-modes": [
+    "/ft8.js", "/ft4.js", "/ft2.js", "/wspr.js", "/cw.js", "/background-decode.js",
+    "/sat.js", "/wefax.js", "/ais.js", "/vdes.js", "/aprs.js", "/hf-aprs.js",
+  ],
   "map-data": ["/map-core.js", "/ais.js", "/vdes.js", "/aprs.js", "/hf-aprs.js"],
   map: ["/map-core.js", "/ais.js", "/vdes.js", "/aprs.js", "/hf-aprs.js", "/sat.js", "/sat-scheduler.js"],
   statistics: ["/map-core.js"],

src/trx-client/trx-frontend/trx-frontend-http/frontend/tests/decode-flow.mjs

@@ -0,0 +1,166 @@
+// SPDX-FileCopyrightText: 2026 Stan Grams <sjg@haxx.space>
+//
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+// What happens to a decode after it arrives: the panel on its tab, the mini
+// view over the waterfall, the marker on the map, and the link between them.
+// Nothing exercised this before — the fixture served an empty decode stream —
+// which is how the map links came to be broken for every decoder at once.
+
+import assert from "node:assert/strict";
+import { chromium } from "playwright-core";
+import { startBrowser, startWebFixture } from "./web-fixture.mjs";
+
+/* global document, getComputedStyle, window, location */
+
+const VESSEL = {
+  type: "ais", mmsi: 244660000, lat: 52.37, lon: 4.89, vessel_name: "NEDERLAND",
+  callsign: "PBTX", sog_knots: 8.2, cog_deg: 91, channel: "A", message_type: 1, rig_id: "rig-a",
+};
+const BEACON = {
+  type: "aprs", src_call: "SP2SJG-9", dest_call: "APRS", path: "WIDE1-1", info: "Test beacon",
+  packet_type: "position", crc_ok: true, lat: 54.35, lon: 18.65,
+  symbol_table: "/", symbol_code: ">", rig_id: "rig-a",
+};
+
+// AIS is what the mini view for vessels is gated on; the rig has to be on it.
+const fixture = await startWebFixture({ spectrum: true, decodes: [VESSEL, BEACON], mode: "AIS" });
+const { browser, page, runtimeErrors } = await startBrowser(chromium);
+
+try {
+  await page.setViewportSize({ width: 1500, height: 950 });
+  await page.goto(`${fixture.origin}/digital-modes`, { waitUntil: "domcontentloaded" });
+  await page.locator("#tab-digital-modes").waitFor({ state: "visible" });
+  await page.waitForTimeout(2000);
+
+  // The decoders with panels on this tab have to load with it. They used to
+  // come only with the map group, so these panels stayed empty — decodes
+  // queued in the plugin runtime — until something opened the Map tab.
+  const panels = await page.evaluate(() => ({
+    ais: document.getElementById("ais-messages")?.children.length ?? 0,
+    aprs: document.getElementById("aprs-packets")?.children.length ?? 0,
+    aisStatus: document.getElementById("ais-status")?.textContent ?? "",
+    aprsStatus: document.getElementById("aprs-status")?.textContent ?? "",
+    mapLoaded: !!window.trx.modules.map,
+  }));
+  assert.equal(panels.mapLoaded, false, "the map module was loaded, so this proves nothing");
+  assert.ok(panels.ais > 0, `the AIS panel is empty (status: ${panels.aisStatus})`);
+  assert.ok(panels.aprs > 0, `the APRS panel is empty (status: ${panels.aprsStatus})`);
+
+  // The mini view rides over the waterfall on the radio page.
+  await page.locator('.tab[data-tab="main"]').click();
+  await page.waitForTimeout(1500);
+  const miniView = await page.evaluate(() => {
+    const bar = document.getElementById("ais-bar-overlay");
+    return {
+      shown: getComputedStyle(bar).display !== "none",
+      pins: bar.querySelectorAll(".aprs-bar-pin").length,
+      names: bar.textContent.includes("NEDERLAND"),
+    };
+  });
+  assert.equal(miniView.shown, true, "the AIS mini view did not appear");
+  assert.ok(miniView.pins > 0, "the mini view has no pin to follow");
+  assert.equal(miniView.names, true, "the mini view does not name the vessel");
+
+  // Following the pin: the map opens, on the vessel. This is the path that was
+  // broken for every decoder — the module that owned the navigation had not
+  // been loaded, so the pin did nothing at all.
+  await page.locator("#ais-bar-overlay .aprs-bar-pin").first().click();
+  await page.locator("#aprs-map .leaflet-pane").first().waitFor({ state: "attached" });
+  await page.waitForTimeout(800);
+  const followed = await page.evaluate(() => {
+    const centre = window.trx.modules.map?.aprsMap?.getCenter?.();
+    return {
+      path: location.pathname,
+      lat: centre ? Number(centre.lat.toFixed(2)) : null,
+      lon: centre ? Number(centre.lng.toFixed(2)) : null,
+    };
+  });
+  assert.equal(followed.path, "/map", `the pin left the page on ${followed.path}`);
+  assert.equal(followed.lat, VESSEL.lat, `the map centred on ${followed.lat}, not the vessel`);
+  assert.equal(followed.lon, VESSEL.lon, `the map centred on ${followed.lon}, not the vessel`);
+
+  // Both decoders put their own marker on it.
+  await page.waitForTimeout(1200);
+  const markers = await page.evaluate(() => {
+    const map = window.trx.modules.map;
+    const size = (collection) => (collection instanceof Map
+      ? collection.size
+      : Object.keys(collection ?? {}).length);
+    return { ais: size(map?.aisMarkers), stations: size(map?.stationMarkers) };
+  });
+  assert.ok(markers.ais > 0, "the vessel never reached the map");
+  assert.ok(markers.stations > 0, "the APRS station never reached the map");
+
+  assert.deepEqual(runtimeErrors, []);
+} finally {
+  await browser.close();
+  await fixture.close();
+}
+
+// Stored history, which is what is on screen a second after a page load. The
+// endpoint answers in CBOR, so the fixture speaks CBOR: serving anything else
+// left the client on its retry path and the history path untested.
+const HISTORY_AIS = 900;
+const HISTORY_APRS = 300;
+const historyFixture = await startWebFixture({
+  spectrum: true,
+  mode: "AIS",
+  history: {
+    ais: Array.from({ length: HISTORY_AIS }, (_, index) => ({
+      mmsi: 244660000 + index, lat: 52.3 + index * 0.001, lon: 4.8,
+      vessel_name: `HISTORIC ${index}`, channel: "A", message_type: 1,
+      rig_id: "rig-a", ts_ms: Date.now() - (index + 1) * 1000,
+    })),
+    aprs: Array.from({ length: HISTORY_APRS }, (_, index) => ({
+      src_call: `SP2SJG-${index % 15}`, dest_call: "APRS", path: "WIDE1-1",
+      info: `history ${index}`, packet_type: "position", crc_ok: true,
+      lat: 54.3, lon: 18.6, rig_id: "rig-a", ts_ms: Date.now() - (index + 1) * 1000,
+    })),
+  },
+});
+const replay = await startBrowser(chromium);
+
+try {
+  await replay.page.setViewportSize({ width: 1400, height: 900 });
+  await replay.page.goto(`${historyFixture.origin}/digital-modes`, { waitUntil: "domcontentloaded" });
+  await replay.page.locator("#tab-digital-modes").waitFor({ state: "visible" });
+
+  // While it loads, the operator can still see the radio. This used to be a
+  // full-screen scrim over everything for as long as the replay ran.
+  const samples = [];
+  for (let attempt = 0; attempt < 30; attempt++) {
+    samples.push(await replay.page.evaluate(() => {
+      const element = document.getElementById("decode-history-overlay");
+      if (!element || element.classList.contains("is-hidden")) return null;
+      const rect = element.getBoundingClientRect();
+      return {
+        width: Math.round(rect.width),
+        coversCentre: document.elementFromPoint(700, 450)?.id === "decode-history-overlay",
+      };
+    }));
+    await replay.page.waitForTimeout(100);
+  }
+  const shown = samples.filter(Boolean);
+  assert.ok(shown.length > 0, "no progress was shown while the history loaded");
+  for (const sample of shown) {
+    assert.ok(sample.width < 700, `the progress covers ${sample.width}px of a 1400px page`);
+    assert.equal(sample.coversCentre, false, "the progress sits over the page");
+  }
+
+  // And all of it arrives, on the first load.
+  await replay.page.waitForTimeout(2000);
+  const restored = await replay.page.evaluate(() => ({
+    ais: document.getElementById("ais-messages")?.children.length ?? 0,
+    aprs: document.getElementById("aprs-packets")?.children.length ?? 0,
+    progressHidden: document.getElementById("decode-history-overlay").classList.contains("is-hidden"),
+  }));
+  assert.equal(restored.ais, HISTORY_AIS, `restored ${restored.ais} of ${HISTORY_AIS} AIS records`);
+  assert.equal(restored.aprs, HISTORY_APRS, `restored ${restored.aprs} of ${HISTORY_APRS} APRS records`);
+  assert.equal(restored.progressHidden, true, "the progress stayed up after the replay finished");
+
+  assert.deepEqual(replay.runtimeErrors, []);
+} finally {
+  await replay.browser.close();
+  await historyFixture.close();
+}

src/trx-client/trx-frontend/trx-frontend-http/frontend/tests/web-fixture.mjs

@@ -44,6 +44,68 @@ const CONTENT_TYPES = new Map([
   [".woff2", "font/woff2"],
 ]);
 
+// The history endpoint answers in CBOR (see api/decoder.rs), and the worker
+// that reads it takes the body as CBOR unconditionally. Serving JSON here left
+// every run exercising the client's retry path instead of its history path.
+function encodeCbor(value) {
+  const chunks = [];
+  const head = (major, length) => {
+    if (length < 24) return Buffer.from([(major << 5) | length]);
+    if (length < 0x100) return Buffer.from([(major << 5) | 24, length]);
+    if (length < 0x10000) {
+      const buffer = Buffer.alloc(3);
+      buffer[0] = (major << 5) | 25;
+      buffer.writeUInt16BE(length, 1);
+      return buffer;
+    }
+    if (length < 0x1_0000_0000) {
+      const buffer = Buffer.alloc(5);
+      buffer[0] = (major << 5) | 26;
+      buffer.writeUInt32BE(length, 1);
+      return buffer;
+    }
+    // Timestamps are past 2^32 milliseconds, so the 64-bit form is needed.
+    const buffer = Buffer.alloc(9);
+    buffer[0] = (major << 5) | 27;
+    buffer.writeBigUInt64BE(BigInt(length), 1);
+    return buffer;
+  };
+  const write = (item) => {
+    if (item === null || item === undefined) { chunks.push(Buffer.from([0xf6])); return; }
+    if (typeof item === "boolean") { chunks.push(Buffer.from([item ? 0xf5 : 0xf4])); return; }
+    if (typeof item === "number") {
+      if (Number.isInteger(item) && item >= 0) { chunks.push(head(0, item)); return; }
+      if (Number.isInteger(item) && item < 0) { chunks.push(head(1, -item - 1)); return; }
+      const buffer = Buffer.alloc(9);
+      buffer[0] = 0xfb;
+      buffer.writeDoubleBE(item, 1);
+      chunks.push(buffer);
+      return;
+    }
+    if (typeof item === "string") {
+      const bytes = Buffer.from(item, "utf8");
+      chunks.push(head(3, bytes.length), bytes);
+      return;
+    }
+    if (Array.isArray(item)) {
+      chunks.push(head(4, item.length));
+      item.forEach(write);
+      return;
+    }
+    const entries = Object.entries(item);
+    chunks.push(head(5, entries.length));
+    for (const [key, entryValue] of entries) {
+      const keyBytes = Buffer.from(key, "utf8");
+      chunks.push(head(3, keyBytes.length), keyBytes);
+      write(entryValue);
+    }
+  };
+  write(value);
+  return Buffer.concat(chunks);
+}
+
+const HISTORY_GROUPS = ["ais", "vdes", "aprs", "hf_aprs", "cw", "ft8", "ft4", "ft2", "wspr", "wefax"];
+
 function assetPath(urlPath) {
   // Every tab route has its own index handler on the server (see api/assets.rs),
   // so a deep link or a refresh serves the SPA shell, not a 404.
@@ -65,6 +127,9 @@ export async function startWebFixture({
   spectrum = false,
   tx = false,
   meterDb = -70,
+  decodes = [],
+  mode = "FM",
+  history = {},
   bookmarks = [],
   bandplan = {},
   bandplanEnabled = false,
@@ -112,7 +177,7 @@ export async function startWebFixture({
         signal_meter: spectrum,
       },
     },
-    status: { freq: { hz: 100_000_000 }, mode: "FM", tx_en: false, vfo: null, tx: null, rx: { sig: meterDb }, lock: null },
+    status: { freq: { hz: 100_000_000 }, mode, tx_en: false, vfo: null, tx: null, rx: { sig: meterDb }, lock: null },
     // Reported only by SDR backends, and what makes the client show the
     // squelch control at all.
     filter: spectrum
@@ -228,6 +293,37 @@ export async function startWebFixture({
       request.on("close", () => clearInterval(timer));
       return;
     }
+    // Decodes arrive on this stream in the server's own shape: a routing
+    // "type" naming the decoder, snake_case fields inside. The mini views, the
+    // map markers and the history all hang off it, and serving nothing left
+    // every one of them untested.
+    if (url.pathname === "/decode/history") {
+      const payload = Object.fromEntries(HISTORY_GROUPS.map((group) => [group, history[group] ?? []]));
+      response.writeHead(200, { "content-type": "application/cbor" });
+      response.end(encodeCbor(payload));
+      return;
+    }
+    if (url.pathname === "/decode") {
+      response.writeHead(200, {
+        "cache-control": "no-cache",
+        connection: "keep-alive",
+        "content-type": "text/event-stream",
+      });
+      response.write(": decode stream\n\n");
+      // Repeats: a live decoder keeps producing, and the views that collapse
+      // by station or vessel need more than one frame to behave like they do
+      // in front of a radio.
+      let sent = 0;
+      const timer = setInterval(() => {
+        if (!decodes.length) return;
+        const decode = decodes[sent++ % decodes.length];
+        // Stamped as they leave: the client prunes anything older than the
+        // retention window, so a fixed epoch would be dropped on arrival.
+        response.write(`data: ${JSON.stringify({ ts_ms: Date.now(), ...decode })}\n\n`);
+      }, 400);
+      request.on("close", () => clearInterval(timer));
+      return;
+    }
     if (["/events", "/decode", "/spectrum", "/meter"].includes(url.pathname)) {
       response.writeHead(200, {
         "cache-control": "no-cache",