Add explicit per-plan gauge temperature offset

shared/curve.js

@@ -9,11 +9,14 @@ const numeric = (v) =>
     ? Number(v)
     : null;
 
-// No roaster selection, learned median, or override changes these illustrative points.
+// An explicit per-plan gauge offset is a temperature difference: no +32 conversion.
+// Legacy roaster selection, learned medians, and machine overrides remain ignored.
+export const planTemperatureOffsetF = (plan) => numeric(plan?.temperatureOffsetF) ?? 0;
 export function buildPlanCurve(plan, ledger) {
   const t = plan.temps ?? {};
-  const fc = numeric(t.fc?.tempC) ?? 200;
-  const yellow = numeric(t.yellow?.tempC) ?? 160;
+  const offsetC = planTemperatureOffsetF(plan) / 1.8;
+  const fc = numeric(t.fc?.tempC) ?? (200 + offsetC);
+  const yellow = numeric(t.yellow?.tempC) ?? (160 + offsetC);
   const maillardRate =
     ledger.maillard > 0 ? Math.max(0, (fc - yellow) / ledger.maillard) : 0;
   // Development's mean rise is lower than Maillard's, even for a short development.
@@ -23,13 +26,13 @@ export function buildPlanCurve(plan, ledger) {
       key: "charge",
       label: "Charge",
       timeS: 0,
-      tempC: numeric(t.charge?.tempC) ?? 200,
+      tempC: numeric(t.charge?.tempC) ?? (200 + offsetC),
     },
     {
       key: "tp",
       label: "Turning point",
       timeS: t.tp?.time ? parseDuration(t.tp.time) : 60,
-      tempC: numeric(t.tp?.tempC) ?? 95,
+      tempC: numeric(t.tp?.tempC) ?? (95 + offsetC),
     },
     {
       key: "yellow",

shared/fields.js

@@ -19,6 +19,7 @@ export function blankPlan() {
   return {
     schemaVersion: 1,
     sourceUrl: "",
+    temperatureOffsetF: "",
     fields,
     blendComponents: [
       { cultivar: "", group: "", process: "", sharePct: "", fcAnchor: "" },

shared/report.js

@@ -1,6 +1,7 @@
 import { computeLedger } from "./ledger.js?v=__ASSET_VERSION__";
 import {
   buildPlanCurve,
+  planTemperatureOffsetF,
   pointsToPathD,
   curveWarnings,
 } from "./curve.js?v=__ASSET_VERSION__";
@@ -121,6 +122,7 @@ export function renderReportBody(plan, name = "") {
  <h2>Coffee & roast intent</h2><p><b>Origin:</b> ${e(fields["1.3"] || "—")} · <b>Cultivar:</b> ${e(fields["1.1"] || "—")} · <b>Density:</b> ${e(fields["5.2"] || "—")} g/L</p><p><b>Weight-loss target:</b> ${e(fields["4.2"] || "—")}% · <b>Development:</b> ${time(l.C)} · <b>DTR:</b> ${l.checks.dtr.pct?.toFixed(1) ?? "—"}%</p>
  <div class="callout">Use this as a starting hypothesis. Light, fruity coffee depends on the green coffee, roast progression and cup results. Machine selection never changes this plan. * Blank temperatures use an illustrative reference curve, not measured or calibrated targets.</div>
  ${warnings.length ? `<div class="callout">${warnings.map((w) => `<p>${e(w)}</p>`).join("")}</div>` : ""}
+ ${planTemperatureOffsetF(plan) ? `<p><b>Gauge temperature offset:</b> ${planTemperatureOffsetF(plan) > 0 ? "+" : ""}${e(planTemperatureOffsetF(plan))}°F. Applied to illustrative temperature references; drop follows adjusted milestones. Entered targets, preheat and actual readings are unchanged.</p>` : ""}
  <h2>Milestone plan</h2><table><thead><tr><th>Milestone</th><th>Time</th><th>BT (°F)</th><th>What to look for</th></tr></thead><tbody>${rows}</tbody></table>
  <h2>Roast curve</h2><div class="chart">${renderReportCurve(p, l)}</div><p>The smooth line interpolates milestones; it is not a predicted sensor trace. Aim for controlled progression after recovery. Phase averages cannot rule out a brief crash or flick.</p><div class="footer">Roast plan · Grams & Fahrenheit</div></section>
  <section class="sheet"><div class="record-intro"><h1>Roast schedule & record</h1><div class="subtitle">${e(name || fields["0.1"] || "Roast plan")} · Use at the roaster</div>