diff --git a/docs/_javascript/preset_test.js b/docs/_javascript/preset_test.js
index e059e1b8..5de9023c 100644
--- a/docs/_javascript/preset_test.js
+++ b/docs/_javascript/preset_test.js
@@ -4,10 +4,12 @@
   const DEFAULTS = Object.freeze({
     start: "2026-09-21T17:00:00-07:00",
     end: "2026-09-23T17:00:00-07:00",
+    tz: "America/Los_Angeles",
     freq: "910.1",
     bw: "500",
     sf: "8",
     cr: "7",
+    tx: "22",
   });
   const VALID_BANDWIDTHS = Object.freeze([
     7.8, 10.4, 15.6, 20.8, 31.25, 41.7, 62.5, 125, 250, 500,
@@ -30,6 +32,18 @@
     return parsed;
   }
 
+  function strictSignedNumber(value, name) {
+    const text = String(value).trim();
+    if (!/^[+-]?(?:\d+(?:\.\d*)?|\.\d+)$/.test(text)) {
+      throw new PresetTestError(name + " must be a decimal number");
+    }
+    const parsed = Number(text);
+    if (!Number.isFinite(parsed)) {
+      throw new PresetTestError(name + " is outside the supported range");
+    }
+    return parsed;
+  }
+
   function strictInteger(value, name) {
     const text = String(value).trim();
     if (!/^\d+$/.test(text)) {
@@ -65,6 +79,21 @@
     return String(Number(value));
   }
 
+  function validateTimeZone(value) {
+    const text = String(value || "").trim();
+    if (!text) {
+      throw new PresetTestError("tz must be an IANA time zone such as America/Los_Angeles");
+    }
+    try {
+      return new Intl.DateTimeFormat("en-US", { timeZone: text })
+        .resolvedOptions().timeZone;
+    } catch (error) {
+      throw new PresetTestError(
+        "tz must be a valid IANA time zone such as America/Los_Angeles or UTC"
+      );
+    }
+  }
+
   function configFromSearch(search) {
     const params = new URLSearchParams(search || "");
     const raw = {};
@@ -74,10 +103,12 @@
 
     const startMs = parseTimestamp(raw.start, "start");
     const endMs = parseTimestamp(raw.end, "end");
+    const tz = validateTimeZone(raw.tz);
     const freq = strictNumber(raw.freq, "freq");
     const bw = strictNumber(raw.bw, "bw");
     const sf = strictInteger(raw.sf, "sf");
     const cr = strictInteger(raw.cr, "cr");
+    const tx = strictSignedNumber(raw.tx, "tx");
 
     if (endMs <= startMs) {
       throw new PresetTestError("end must be later than start");
@@ -98,18 +129,24 @@
     if (cr < 5 || cr > 8) {
       throw new PresetTestError("cr must be between 5 and 8");
     }
+    if (tx < -30 || tx > 60) {
+      throw new PresetTestError("tx must be between -30 and 60 dBm");
+    }
 
     return Object.freeze({
       startMs: startMs,
       endMs: endMs,
       startEpoch: Math.floor(startMs / 1000),
       endEpoch: Math.floor(endMs / 1000),
+      tz: tz,
       freq: freq,
       bw: bw,
       sf: sf,
       cr: cr,
+      tx: tx,
       freqText: numberText(freq),
       bwText: numberText(bw),
+      txText: numberText(tx),
     });
   }
 
@@ -155,9 +192,36 @@
         config.startEpoch + "," + config.endEpoch + "\nget tempradioat2",
       stockCancelBefore: "get tempradioat\ndel tempradioat all",
       stockCancelDuring: "normalradio",
+      stockLeaveIn30: "tempradio " + tuple + ",30",
       companionCancelBefore:
         "get tempradioat2\ndel tempradioat2 all\nset radio2.cross auto",
       companionCancelDuring: "set tempradio2 off\nset radio2.cross auto",
+      companionLeaveIn30:
+        "set radio2.cross on\ndel tempradioat2 all\nset tempradio2 " +
+        tuple + ",rxtx,30",
+    });
+  }
+
+  function radioEstimates(config) {
+    const requiredSnr = {
+      5: -2.5,
+      6: -5,
+      7: -7.5,
+      8: -10,
+      9: -12.5,
+      10: -15,
+      11: -17.5,
+      12: -20,
+    }[config.sf];
+    const bandwidthHz = config.bw * 1000;
+    const bitrateKbps = (
+      config.sf * (4 / config.cr) * bandwidthHz / Math.pow(2, config.sf)
+    ) / 1000;
+    const sensitivityDbm = -174 + 10 * Math.log10(bandwidthHz) + 6 + requiredSnr;
+    return Object.freeze({
+      bitrateKbps: bitrateKbps,
+      sensitivityDbm: sensitivityDbm,
+      linkBudgetDb: config.tx - sensitivityDbm,
     });
   }
 
@@ -177,9 +241,9 @@
     return parts.join(" ");
   }
 
-  function formatPacific(milliseconds) {
+  function formatZoned(milliseconds, timeZone) {
     return new Intl.DateTimeFormat("en-US", {
-      timeZone: "America/Los_Angeles",
+      timeZone: timeZone,
       weekday: "long",
       year: "numeric",
       month: "long",
@@ -190,6 +254,125 @@
     }).format(new Date(milliseconds));
   }
 
+  function zonedParts(milliseconds, timeZone) {
+    const result = {};
+    new Intl.DateTimeFormat("en-US", {
+      timeZone: timeZone,
+      year: "numeric",
+      month: "2-digit",
+      day: "2-digit",
+      hour: "2-digit",
+      minute: "2-digit",
+      second: "2-digit",
+      hourCycle: "h23",
+    }).formatToParts(new Date(milliseconds)).forEach(function (part) {
+      if (part.type !== "literal") result[part.type] = Number(part.value);
+    });
+    return result;
+  }
+
+  function twoDigits(value) {
+    return String(value).padStart(2, "0");
+  }
+
+  function zonedInputValue(milliseconds, timeZone) {
+    const parts = zonedParts(milliseconds, timeZone);
+    return String(parts.year).padStart(4, "0") + "-" +
+      twoDigits(parts.month) + "-" + twoDigits(parts.day) + "T" +
+      twoDigits(parts.hour) + ":" + twoDigits(parts.minute);
+  }
+
+  function parseLocalDateTime(value, name) {
+    const text = String(value || "").trim();
+    const match = /^(\d{4})-(\d{2})-(\d{2})T(\d{2}):(\d{2})(?::(\d{2}))?$/.exec(text);
+    if (!match) {
+      throw new PresetTestError(name + " must include a date and time");
+    }
+    const parts = {
+      year: Number(match[1]),
+      month: Number(match[2]),
+      day: Number(match[3]),
+      hour: Number(match[4]),
+      minute: Number(match[5]),
+      second: Number(match[6] || 0),
+    };
+    const checked = new Date(Date.UTC(
+      parts.year, parts.month - 1, parts.day,
+      parts.hour, parts.minute, parts.second
+    ));
+    if (checked.getUTCFullYear() !== parts.year ||
+        checked.getUTCMonth() + 1 !== parts.month ||
+        checked.getUTCDate() !== parts.day ||
+        checked.getUTCHours() !== parts.hour ||
+        checked.getUTCMinutes() !== parts.minute ||
+        checked.getUTCSeconds() !== parts.second) {
+      throw new PresetTestError(name + " is not a valid calendar date and time");
+    }
+    return parts;
+  }
+
+  function sameDateTime(left, right) {
+    return left.year === right.year && left.month === right.month &&
+      left.day === right.day && left.hour === right.hour &&
+      left.minute === right.minute && left.second === right.second;
+  }
+
+  function offsetAt(milliseconds, timeZone) {
+    const parts = zonedParts(milliseconds, timeZone);
+    const rounded = Math.floor(milliseconds / 1000) * 1000;
+    return Date.UTC(
+      parts.year, parts.month - 1, parts.day,
+      parts.hour, parts.minute, parts.second
+    ) - rounded;
+  }
+
+  function localDateTimeToMs(value, timeZone, name) {
+    const label = name || "date and time";
+    const zone = validateTimeZone(timeZone);
+    const desired = parseLocalDateTime(value, label);
+    const wallMilliseconds = Date.UTC(
+      desired.year, desired.month - 1, desired.day,
+      desired.hour, desired.minute, desired.second
+    );
+    const offsets = new Set();
+    for (let hours = -48; hours <= 48; hours += 6) {
+      offsets.add(offsetAt(wallMilliseconds + hours * 60 * 60 * 1000, zone));
+    }
+    const matches = Array.from(offsets).map(function (offset) {
+      return wallMilliseconds - offset;
+    }).filter(function (candidate) {
+      return sameDateTime(zonedParts(candidate, zone), desired);
+    }).sort(function (left, right) { return left - right; });
+
+    if (matches.length === 0) {
+      throw new PresetTestError(
+        label + " does not exist in " + zone + " because of a clock change"
+      );
+    }
+    if (matches.length > 1) {
+      throw new PresetTestError(
+        label + " is ambiguous in " + zone + " because of a clock change"
+      );
+    }
+    return matches[0];
+  }
+
+  function configFromGenerator(values) {
+    const tz = validateTimeZone(values.tz);
+    const startMs = localDateTimeToMs(values.start, tz, "start");
+    const endMs = localDateTimeToMs(values.end, tz, "end");
+    const params = new URLSearchParams();
+    params.set("start", new Date(startMs).toISOString());
+    params.set("end", new Date(endMs).toISOString());
+    params.set("tz", tz);
+    params.set("freq", values.freq);
+    params.set("bw", values.bw);
+    params.set("sf", values.sf);
+    params.set("cr", values.cr);
+    params.set("tx", values.tx);
+    return configFromSearch("?" + params.toString());
+  }
+
   function formatUtc(milliseconds) {
     return new Intl.DateTimeFormat("en-US", {
       timeZone: "UTC",
@@ -209,10 +392,12 @@
     url.search = "";
     url.searchParams.set("start", new Date(config.startMs).toISOString());
     url.searchParams.set("end", new Date(config.endMs).toISOString());
+    url.searchParams.set("tz", config.tz);
     url.searchParams.set("freq", config.freqText);
     url.searchParams.set("bw", config.bwText);
     url.searchParams.set("sf", String(config.sf));
     url.searchParams.set("cr", String(config.cr));
+    url.searchParams.set("tx", config.txText);
     return url.toString();
   }
 
@@ -287,8 +472,9 @@
     setText(root, '[data-field="bw-display"]', config.bwText);
     setText(root, '[data-field="sf"]', String(config.sf));
     setText(root, '[data-field="cr"]', String(config.cr));
-    setText(root, '[data-role="start-pacific"]', formatPacific(config.startMs));
-    setText(root, '[data-role="end-pacific"]', formatPacific(config.endMs));
+    setText(root, '[data-role="start-zoned"]', formatZoned(config.startMs, config.tz));
+    setText(root, '[data-role="end-zoned"]', formatZoned(config.endMs, config.tz));
+    setText(root, '[data-role="display-zone"]', config.tz);
     setText(
       root,
       '[data-role="epoch-range"]',
@@ -306,14 +492,86 @@
     setCommand(root, "companion-scheduled", staticCommands.companionScheduled);
     setCommand(root, "stock-cancel-before", staticCommands.stockCancelBefore);
     setCommand(root, "stock-cancel-during", staticCommands.stockCancelDuring);
+    setCommand(root, "stock-leave-30", staticCommands.stockLeaveIn30);
     setCommand(root, "companion-cancel-before", staticCommands.companionCancelBefore);
     setCommand(root, "companion-cancel-during", staticCommands.companionCancelDuring);
+    setCommand(root, "companion-leave-30", staticCommands.companionLeaveIn30);
     setCommand(root, "reset-clock", CLOCK_RESET_COMMAND);
-    setCommand(
-      root,
-      "share-url",
-      configuredUrl(config, global.location ? global.location.href : "https://example.invalid/")
-    );
+
+    const generator = root.querySelector('[data-role="url-generator"]');
+    if (generator) {
+      generator.elements.start.value = zonedInputValue(config.startMs, config.tz);
+      generator.elements.end.value = zonedInputValue(config.endMs, config.tz);
+      generator.elements.tz.value = config.tz;
+      generator.elements.freq.value = config.freqText;
+      generator.elements.bw.value = config.bwText;
+      generator.elements.sf.value = String(config.sf);
+      generator.elements.cr.value = String(config.cr);
+      generator.elements.tx.value = config.txText;
+
+      const zoneList = root.querySelector("#preset-test-time-zones");
+      if (zoneList && typeof Intl.supportedValuesOf === "function") {
+        Intl.supportedValuesOf("timeZone").forEach(function (zone) {
+          if (!zoneList.querySelector('option[value="' + zone + '"]')) {
+            const option = document.createElement("option");
+            option.value = zone;
+            zoneList.appendChild(option);
+          }
+        });
+      }
+
+      function generateUrl() {
+        const errorBox = root.querySelector('[data-role="generator-error"]');
+        try {
+          const generated = configFromGenerator({
+            start: generator.elements.start.value,
+            end: generator.elements.end.value,
+            tz: generator.elements.tz.value,
+            freq: generator.elements.freq.value,
+            bw: generator.elements.bw.value,
+            sf: generator.elements.sf.value,
+            cr: generator.elements.cr.value,
+            tx: generator.elements.tx.value,
+          });
+          const url = configuredUrl(
+            generated,
+            global.location ? global.location.href : "https://example.invalid/"
+          );
+          setCommand(root, "generated-url", url);
+          setCommandEnabled(root, "generated-url", true);
+          const estimates = radioEstimates(generated);
+          setText(root, '[data-role="estimate-rate"]', estimates.bitrateKbps.toFixed(2) + " kbps");
+          setText(root, '[data-role="estimate-sensitivity"]', estimates.sensitivityDbm.toFixed(1) + " dBm");
+          setText(root, '[data-role="estimate-budget"]', estimates.linkBudgetDb.toFixed(1) + " dB");
+          setText(root, '[data-role="estimate-tx"]', generated.txText + " dBm");
+          const openLink = root.querySelector('[data-role="open-generated-url"]');
+          if (openLink) {
+            openLink.href = url;
+            openLink.hidden = false;
+          }
+          if (errorBox) {
+            errorBox.textContent = "";
+            errorBox.hidden = true;
+          }
+        } catch (error) {
+          setCommand(root, "generated-url", "Fix the highlighted configuration error first.");
+          setCommandEnabled(root, "generated-url", false);
+          const openLink = root.querySelector('[data-role="open-generated-url"]');
+          if (openLink) openLink.hidden = true;
+          if (errorBox) {
+            errorBox.textContent = error.message;
+            errorBox.hidden = false;
+          }
+        }
+      }
+
+      generator.addEventListener("submit", function (event) {
+        event.preventDefault();
+        generateUrl();
+      });
+      generator.addEventListener("change", generateUrl);
+      generateUrl();
+    }
 
     root.querySelectorAll("[data-copy-command]").forEach(function (button) {
       button.addEventListener("click", function () {
@@ -418,12 +676,18 @@
     CLOCK_RESET_COMMAND: CLOCK_RESET_COMMAND,
     PresetTestError: PresetTestError,
     configFromSearch: configFromSearch,
+    configFromGenerator: configFromGenerator,
+    validateTimeZone: validateTimeZone,
     phaseAt: phaseAt,
     remainingMinutes: remainingMinutes,
     immediateAvailable: immediateAvailable,
     scheduleAvailability: scheduleAvailability,
     commandsFor: commandsFor,
+    radioEstimates: radioEstimates,
     formatCountdown: formatCountdown,
+    formatZoned: formatZoned,
+    zonedInputValue: zonedInputValue,
+    localDateTimeToMs: localDateTimeToMs,
     configuredUrl: configuredUrl,
     init: init,
   });
diff --git a/docs/_stylesheets/preset_test.css b/docs/_stylesheets/preset_test.css
index 30df5b77..c383a6c9 100644
--- a/docs/_stylesheets/preset_test.css
+++ b/docs/_stylesheets/preset_test.css
@@ -244,10 +244,139 @@
   font-family: var(--md-code-font-family);
 }
 
+.preset-test-generator-layout {
+  display: grid;
+  grid-template-columns: minmax(0, 3fr) minmax(15rem, 2fr);
+  gap: 1rem;
+  align-items: start;
+}
+
+.preset-test-generator,
+.preset-test-estimates {
+  min-width: 0;
+  border: 1px solid var(--preset-border);
+  border-radius: 0.65rem;
+  padding: 1rem;
+  background: var(--md-default-bg-color);
+}
+
+.preset-test-generator-fields {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 0.8rem;
+}
+
+.preset-test-generator label {
+  display: grid;
+  align-content: start;
+  gap: 0.25rem;
+  min-width: 0;
+}
+
+.preset-test-generator label > span {
+  font-size: 0.78rem;
+  font-weight: 700;
+}
+
+.preset-test-generator input,
+.preset-test-generator select {
+  box-sizing: border-box;
+  width: 100%;
+  min-width: 0;
+  border: 1px solid var(--preset-border);
+  border-radius: 0.3rem;
+  padding: 0.52rem 0.58rem;
+  background: var(--md-default-bg-color);
+  color: var(--md-default-fg-color);
+  font: inherit;
+}
+
+.preset-test-generator input:focus,
+.preset-test-generator select:focus {
+  border-color: var(--preset-cyan);
+  outline: 2px solid color-mix(in srgb, var(--preset-cyan) 24%, transparent);
+  outline-offset: 1px;
+}
+
+.preset-test-generator small {
+  color: var(--md-default-fg-color--light);
+  font-size: 0.68rem;
+  line-height: 1.35;
+}
+
+.preset-test-generator > button {
+  margin-top: 0.9rem;
+}
+
+.preset-test-estimates h3 {
+  margin-top: 0;
+}
+
+.preset-test-estimates dl {
+  display: grid;
+  gap: 0.7rem;
+  margin: 0 0 1rem;
+}
+
+.preset-test-estimates dl > div {
+  display: flex;
+  justify-content: space-between;
+  gap: 1rem;
+  border-bottom: 1px solid var(--preset-border);
+  padding-bottom: 0.55rem;
+}
+
+.preset-test-estimates dt {
+  color: var(--md-default-fg-color--light);
+  font-size: 0.74rem;
+  font-weight: 700;
+}
+
+.preset-test-estimates dd {
+  margin: 0;
+  color: var(--preset-accent);
+  font-family: var(--md-code-font-family);
+  font-weight: 750;
+  text-align: right;
+}
+
+.preset-test-generator-error {
+  margin-top: 1rem;
+}
+
+.preset-test-generated-url code {
+  white-space: pre-wrap;
+  overflow-wrap: anywhere;
+}
+
+.preset-test-generator-actions {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 0.65rem;
+  align-items: center;
+}
+
+.preset-test-generator-actions a {
+  border: 1px solid var(--preset-accent);
+  border-radius: 0.25rem;
+  padding: 0.48rem 0.8rem;
+  color: var(--preset-accent);
+  font-size: 0.78rem;
+  font-weight: 750;
+  text-decoration: none;
+}
+
+.preset-test-generator-actions a:hover,
+.preset-test-generator-actions a:focus-visible {
+  background: color-mix(in srgb, var(--preset-accent) 10%, transparent);
+}
+
 @media (max-width: 44rem) {
   .preset-test-grid,
   .preset-test-grid--clock,
-  .preset-test-clock-check {
+  .preset-test-clock-check,
+  .preset-test-generator-layout,
+  .preset-test-generator-fields {
     grid-template-columns: 1fr;
   }
 
diff --git a/docs/preset_test.md b/docs/preset_test.md
index b1cadb1b..dd886275 100644
--- a/docs/preset_test.md
+++ b/docs/preset_test.md
@@ -6,8 +6,8 @@ September 21, 2026 at 5:00 PM through Wednesday, September 23 at 5:00 PM
 Pacific time** (48 hours), using **910.1 MHz, 500 kHz, SF8, CR7**.
 
 The page reads the complete test definition from its URL. Change the query
-parameters to reuse it for a different window or radio tuple; no source edit is
-required.
+parameters to reuse it for a different window, display time zone, or radio
+tuple; no source edit is required.
 
 <div class="preset-test" data-preset-test>
   <div class="preset-test-error" data-role="config-error" role="alert" hidden></div>
@@ -35,8 +35,9 @@ required.
       </div>
 
       <dl class="preset-test-window">
-        <div><dt>Start</dt><dd data-role="start-pacific"></dd></div>
-        <div><dt>End</dt><dd data-role="end-pacific"></dd></div>
+        <div><dt>Start</dt><dd data-role="start-zoned"></dd></div>
+        <div><dt>End</dt><dd data-role="end-zoned"></dd></div>
+        <div><dt>Display time zone</dt><dd data-role="display-zone"></dd></div>
         <div><dt>Firmware epochs</dt><dd><code data-role="epoch-range"></code></dd></div>
       </dl>
     </section>
@@ -211,12 +212,20 @@ clock</code></pre>
 
         <article class="preset-test-card">
           <h3>Stock · while it is running</h3>
+          <h4>Leave now</h4>
           <pre><code data-command="stock-cancel-during"></code></pre>
           <button type="button" data-copy-command="stock-cancel-during">Copy restore command</button>
           <p class="preset-test-note">
             <code>normalradio</code> cancels pending and active primary TempRadio
             windows and restores the saved primary tuple after its reply drains.
           </p>
+          <h4>Leave in 30 minutes</h4>
+          <pre><code data-command="stock-leave-30"></code></pre>
+          <button type="button" data-copy-command="stock-leave-30">Copy 30-minute command</button>
+          <p class="preset-test-note">
+            This replaces the current temporary timeout with 30 minutes, then
+            restores the saved primary tuple automatically.
+          </p>
         </article>
 
         <article class="preset-test-card">
@@ -227,26 +236,133 @@ clock</code></pre>
 
         <article class="preset-test-card">
           <h3>Companion · while it is running</h3>
+          <h4>Leave now</h4>
           <pre><code data-command="companion-cancel-during"></code></pre>
           <button type="button" data-copy-command="companion-cancel-during">Copy restore commands</button>
           <p class="preset-test-note">
             If <code>get radio2.cross</code> was not <code>auto</code> before the
             test, restore that recorded value instead.
           </p>
+          <h4>Leave in 30 minutes</h4>
+          <pre><code data-command="companion-leave-30"></code></pre>
+          <button type="button" data-copy-command="companion-leave-30">Copy 30-minute commands</button>
+          <p class="preset-test-note">
+            These commands clear any absolute second-profile schedule and give
+            the test profile a fresh 30-minute lease. The saved second profile
+            returns at expiry, but crossing remains <code>on</code>; afterward,
+            restore the value you recorded before the test (<code>auto</code> is
+            the normal default).
+          </p>
         </article>
       </div>
     </section>
 
     <section aria-labelledby="share-title">
-      <h2 id="share-title">Reuse this page for another test</h2>
+      <h2 id="share-title">Build a link for another test</h2>
       <p>
-        Set <code>start</code> and <code>end</code> to ISO-8601 timestamps with an
-        explicit UTC offset, or to Unix epoch seconds. Set <code>freq</code>,
-        <code>bw</code>, <code>sf</code>, and <code>cr</code> to the desired radio
-        tuple. The current configuration link is normalized to UTC.
+        Enter the test times in the selected time zone and choose the radio
+        tuple. The generated URL converts the times to exact UTC instants and
+        keeps <code>tz</code> so the page displays them in the organizer's local
+        time zone.
+      </p>
+
+      <div class="preset-test-generator-layout">
+        <form class="preset-test-generator" data-role="url-generator">
+          <div class="preset-test-generator-fields">
+            <label>
+              <span>Start date and time</span>
+              <input type="datetime-local" name="start" step="60" required>
+            </label>
+            <label>
+              <span>End date and time</span>
+              <input type="datetime-local" name="end" step="60" required>
+            </label>
+            <label>
+              <span>Time zone</span>
+              <input type="text" name="tz" list="preset-test-time-zones" required
+                     autocomplete="off" spellcheck="false">
+              <small>Use an IANA name such as America/Los_Angeles or UTC.</small>
+            </label>
+            <label>
+              <span>Frequency (MHz)</span>
+              <input type="number" name="freq" min="150" max="2500" step="0.001" required>
+            </label>
+            <label>
+              <span>Bandwidth (kHz)</span>
+              <select name="bw" required>
+                <option>7.8</option><option>10.4</option><option>15.6</option>
+                <option>20.8</option><option>31.25</option><option>41.7</option>
+                <option>62.5</option><option>125</option><option>250</option><option>500</option>
+              </select>
+            </label>
+            <label>
+              <span>Spreading factor</span>
+              <select name="sf" required>
+                <option>5</option><option>6</option><option>7</option><option>8</option>
+                <option>9</option><option>10</option><option>11</option><option>12</option>
+              </select>
+            </label>
+            <label>
+              <span>Coding-rate denominator</span>
+              <select name="cr" required>
+                <option>5</option><option>6</option><option>7</option><option>8</option>
+              </select>
+            </label>
+            <label>
+              <span>TX output for estimate (dBm)</span>
+              <input type="number" name="tx" min="-30" max="60" step="0.1" required>
+              <small>This estimate-only value does not change the TempRadio commands.</small>
+            </label>
+          </div>
+          <button type="submit">Generate test URL</button>
+        </form>
+
+        <aside class="preset-test-estimates" aria-labelledby="radio-estimates-title">
+          <h3 id="radio-estimates-title">Radio estimates</h3>
+          <dl>
+            <div><dt>Nominal LoRa bitrate</dt><dd data-role="estimate-rate">—</dd></div>
+            <div><dt>Estimated sensitivity</dt><dd data-role="estimate-sensitivity">—</dd></div>
+            <div><dt>TX output used</dt><dd data-role="estimate-tx">—</dd></div>
+            <div><dt>Estimated link budget</dt><dd data-role="estimate-budget">—</dd></div>
+          </dl>
+          <p class="preset-test-note">
+            The bitrate is the nominal LoRa physical-layer rate; usable payload
+            throughput is lower. Sensitivity assumes a 6 dB receiver noise figure
+            and the standard LoRa SNR threshold for the selected spreading factor.
+            Link budget is TX output minus that sensitivity, before antenna gain,
+            cable loss, path loss, interference, and implementation differences.
+          </p>
+        </aside>
+      </div>
+
+      <datalist id="preset-test-time-zones">
+        <option value="America/Los_Angeles"></option>
+        <option value="America/Denver"></option>
+        <option value="America/Chicago"></option>
+        <option value="America/New_York"></option>
+        <option value="America/Phoenix"></option>
+        <option value="Pacific/Honolulu"></option>
+        <option value="UTC"></option>
+        <option value="Europe/London"></option>
+        <option value="Europe/Berlin"></option>
+        <option value="Asia/Tokyo"></option>
+        <option value="Australia/Sydney"></option>
+      </datalist>
+
+      <p class="preset-test-error preset-test-generator-error"
+         data-role="generator-error" role="alert" hidden></p>
+      <pre class="preset-test-generated-url"><code data-command="generated-url"></code></pre>
+      <div class="preset-test-generator-actions">
+        <button type="button" data-copy-command="generated-url">Copy generated URL</button>
+        <a data-role="open-generated-url" target="_blank" rel="noopener">Open generated page</a>
+      </div>
+
+      <p class="preset-test-note">
+        Advanced use: <code>start</code> and <code>end</code> also accept ISO-8601
+        timestamps with explicit UTC offsets or Unix epoch seconds. The other URL
+        parameters are <code>tz</code>, <code>freq</code>, <code>bw</code>,
+        <code>sf</code>, <code>cr</code>, and estimate-only <code>tx</code>.
       </p>
-      <pre><code>?start=2026-09-21T17:00:00-07:00&amp;end=2026-09-23T17:00:00-07:00&amp;freq=910.1&amp;bw=500&amp;sf=8&amp;cr=7</code></pre>
-      <button type="button" data-copy-command="share-url">Copy configured page URL</button>
     </section>
   </div>
 </div>
diff --git a/test/test_preset_test.js b/test/test_preset_test.js
index 11e81c85..dfcba65d 100644
--- a/test/test_preset_test.js
+++ b/test/test_preset_test.js
@@ -16,9 +16,12 @@ assert.strictEqual(config.endEpoch - config.startEpoch, 48 * 60 * 60);
 assert.strictEqual(config.freq, 910.1);
 assert.strictEqual(config.sf, 8);
 assert.strictEqual(config.cr, 7);
+assert.strictEqual(config.tz, "America/Los_Angeles");
+assert.strictEqual(config.tx, 22);
 assert.strictEqual(defaults.startEpoch, config.startEpoch);
 assert.strictEqual(defaults.endEpoch, config.endEpoch);
 assert.strictEqual(defaults.freq, config.freq);
+assert.strictEqual(defaults.tz, config.tz);
 
 const before = Date.parse("2026-09-21T16:59:00-07:00");
 const beforeSetup = Date.parse("2026-09-21T15:59:59-07:00");
@@ -54,6 +57,13 @@ assert.strictEqual(
     "set tempradioat2 910.1,500,8,7,rxtx,1790035200,1790208000\n" +
     "get tempradioat2"
 );
+assert.strictEqual(commands.stockLeaveIn30, "tempradio 910.1,500,8,7,30");
+assert.strictEqual(
+  commands.companionLeaveIn30,
+  "set radio2.cross on\n" +
+    "del tempradioat2 all\n" +
+    "set tempradio2 910.1,500,8,7,rxtx,30"
+);
 
 assert.strictEqual(tool.scheduleAvailability(config, before).available, true);
 assert.strictEqual(tool.scheduleAvailability(config, active).available, false);
@@ -62,6 +72,46 @@ assert.strictEqual(
   false
 );
 
+assert.strictEqual(
+  tool.zonedInputValue(config.startMs, "America/Los_Angeles"),
+  "2026-09-21T17:00"
+);
+assert.strictEqual(
+  tool.zonedInputValue(config.startMs, "America/New_York"),
+  "2026-09-21T20:00"
+);
+assert.strictEqual(
+  tool.localDateTimeToMs("2026-09-21T17:00", "America/Los_Angeles"),
+  config.startMs
+);
+assert.throws(
+  () => tool.localDateTimeToMs("2026-03-08T02:30", "America/Los_Angeles"),
+  /does not exist/
+);
+assert.throws(
+  () => tool.localDateTimeToMs("2026-11-01T01:30", "America/Los_Angeles"),
+  /ambiguous/
+);
+
+const generated = tool.configFromGenerator({
+  start: "2026-09-21T17:00",
+  end: "2026-09-23T17:00",
+  tz: "America/Los_Angeles",
+  freq: "910.1",
+  bw: "500",
+  sf: "8",
+  cr: "7",
+  tx: "22",
+});
+assert.strictEqual(generated.startEpoch, config.startEpoch);
+assert.strictEqual(generated.endEpoch, config.endEpoch);
+assert.strictEqual(generated.tz, "America/Los_Angeles");
+
+const estimates = tool.radioEstimates(config);
+assert.ok(Math.abs(estimates.bitrateKbps - 8.9285714286) < 0.000001);
+assert.ok(Math.abs(estimates.sensitivityDbm - (-121.0102999566)) < 0.000001);
+assert.ok(Math.abs(estimates.linkBudgetDb - 143.0102999566) < 0.000001);
+
 assert.throws(
   () => tool.configFromSearch("?start=bad"),
   /start must include an explicit UTC offset/
@@ -78,6 +128,14 @@ assert.throws(
   () => tool.configFromSearch("?start=1790208000&end=1790035200"),
   /end must be later/
 );
+assert.throws(
+  () => tool.configFromSearch("?tz=Moon%2FTranquility"),
+  /tz must be a valid IANA time zone/
+);
+assert.throws(
+  () => tool.configFromSearch("?tx=61"),
+  /tx must be between/
+);
 
 const changed = tool.configFromSearch(
   "?start=1790035200&end=1790208000&freq=915.25&bw=125&sf=10&cr=5"
@@ -94,6 +152,8 @@ const shared = new URL(tool.configuredUrl(
 assert.strictEqual(shared.searchParams.get("start"), "2026-09-22T00:00:00.000Z");
 assert.strictEqual(shared.searchParams.get("end"), "2026-09-24T00:00:00.000Z");
 assert.strictEqual(shared.searchParams.get("freq"), "915.25");
+assert.strictEqual(shared.searchParams.get("tz"), "America/Los_Angeles");
+assert.strictEqual(shared.searchParams.get("tx"), "22");
 assert.strictEqual(shared.searchParams.has("stale"), false);
 assert.strictEqual(shared.hash, "#commands");