diff --git a/docs/api/openapi.yaml b/docs/api/openapi.yaml
index 1b8fc1dc1..4b7627433 100644
--- a/docs/api/openapi.yaml
+++ b/docs/api/openapi.yaml
@@ -31356,6 +31356,37 @@ components:
           items:
             $ref: "#/components/schemas/DailyPriorityItem"
           description: Bounded 0–3 rail items, never padded.
+        justIn:
+          anyOf:
+            - type: object
+              properties:
+                kind:
+                  type: string
+                  enum:
+                    - sleep_night
+                    - workout
+                    - weight
+                    - blood_pressure
+                    - labs_panel
+                  description: Closed arrival kind that landed.
+                at:
+                  type: string
+                  description: ISO-8601 instant of the newest sample. NEVER pre-formatted server-side — the client formats it in its own
+                    locale and timezone.
+              required:
+                - kind
+                - at
+              additionalProperties: false
+            - type: "null"
+          description: The day's newest data arrival while it is still news (under three hours old), else null. Additive since
+            v1.31.0.
+        reactionLine:
+          anyOf:
+            - type: string
+            - type: "null"
+          description: One-sentence generated reaction to that arrival, standing for the rest of the local day. Null whenever no
+            line was generated (no provider, no consent, budget exhausted, or generation failed) — consumers fall back
+            to `briefingLead` / `line`. Additive since v1.31.0.
       required:
         - generatedAt
         - phase
@@ -31365,6 +31396,8 @@ components:
         - briefingLead
         - line
         - worthALook
+        - justIn
+        - reactionLine
       additionalProperties: false
       description: The one data spine of the daily-value system — composed from already-cached data, never a fresh AI call.
         Consumed by the Today surface, the daily push, and a future iOS widget.
diff --git a/messages/de.json b/messages/de.json
index ad9268086..9f09092c1 100644
--- a/messages/de.json
+++ b/messages/de.json
@@ -8828,6 +8828,8 @@
       "deltaVsBaseline": "{delta} ggü. deinem Ausgangswert",
       "deltaFlat": "Im Bereich deines Ausgangswerts",
       "sleepPending": "Der Schlaf von letzter Nacht fehlt noch – der heutige Wert ist vorläufig.",
+      "justIn": "Gerade eingetroffen",
+      "justInAt": "Gerade eingetroffen · {time}",
       "worthALook": "Einen Blick wert",
       "allClear": "Heute braucht nichts deine Aufmerksamkeit.",
       "ringLink": "{metric}-Details öffnen"
diff --git a/messages/en.json b/messages/en.json
index c78f6c78c..8daca269b 100644
--- a/messages/en.json
+++ b/messages/en.json
@@ -8828,6 +8828,8 @@
       "deltaVsBaseline": "{delta} vs your baseline",
       "deltaFlat": "In line with your baseline",
       "sleepPending": "Last night's sleep isn't in yet — today's read is provisional.",
+      "justIn": "Just in",
+      "justInAt": "Just in · {time}",
       "worthALook": "Worth a look",
       "allClear": "Nothing needs your attention today.",
       "ringLink": "Open {metric} details"
diff --git a/messages/es.json b/messages/es.json
index 7e77e5ed2..bf95ccd5d 100644
--- a/messages/es.json
+++ b/messages/es.json
@@ -8828,6 +8828,8 @@
       "deltaVsBaseline": "{delta} frente a tu valor de referencia",
       "deltaFlat": "En línea con tu valor de referencia",
       "sleepPending": "El sueño de anoche aún no ha llegado; la lectura de hoy es provisional.",
+      "justIn": "Recién llegado",
+      "justInAt": "Recién llegado · {time}",
       "worthALook": "Merece un vistazo",
       "allClear": "Hoy nada necesita tu atención.",
       "ringLink": "Abrir detalles de {metric}"
diff --git a/messages/fr.json b/messages/fr.json
index a390a4c5f..93299fe3c 100644
--- a/messages/fr.json
+++ b/messages/fr.json
@@ -8828,6 +8828,8 @@
       "deltaVsBaseline": "{delta} par rapport à ta référence",
       "deltaFlat": "Conforme à ta référence",
       "sleepPending": "Le sommeil de la nuit dernière n'est pas encore arrivé — la lecture du jour est provisoire.",
+      "justIn": "Vient d'arriver",
+      "justInAt": "Vient d'arriver · {time}",
       "worthALook": "À regarder",
       "allClear": "Rien ne requiert ton attention aujourd'hui.",
       "ringLink": "Ouvrir les détails de {metric}"
diff --git a/messages/it.json b/messages/it.json
index 827c43c5f..aa96c9100 100644
--- a/messages/it.json
+++ b/messages/it.json
@@ -8828,6 +8828,8 @@
       "deltaVsBaseline": "{delta} rispetto al tuo valore di riferimento",
       "deltaFlat": "In linea con il tuo valore di riferimento",
       "sleepPending": "Il sonno di stanotte non è ancora arrivato: la lettura di oggi è provvisoria.",
+      "justIn": "Appena arrivato",
+      "justInAt": "Appena arrivato · {time}",
       "worthALook": "Da tenere d'occhio",
       "allClear": "Oggi nulla richiede la tua attenzione.",
       "ringLink": "Apri i dettagli di {metric}"
diff --git a/messages/pl.json b/messages/pl.json
index a43e94b7f..3ad6046d8 100644
--- a/messages/pl.json
+++ b/messages/pl.json
@@ -8828,6 +8828,8 @@
       "deltaVsBaseline": "{delta} wzgl. Twojej wartości bazowej",
       "deltaFlat": "Zgodnie z Twoją wartością bazową",
       "sleepPending": "Sen z ostatniej nocy jeszcze nie dotarł — dzisiejszy odczyt jest wstępny.",
+      "justIn": "Właśnie dotarło",
+      "justInAt": "Właśnie dotarło · {time}",
       "worthALook": "Warto sprawdzić",
       "allClear": "Dziś nic nie wymaga Twojej uwagi.",
       "ringLink": "Otwórz szczegóły: {metric}"
diff --git a/src/app/api/daily/digest/__tests__/route.test.ts b/src/app/api/daily/digest/__tests__/route.test.ts
index cac7f1bd8..80a297833 100644
--- a/src/app/api/daily/digest/__tests__/route.test.ts
+++ b/src/app/api/daily/digest/__tests__/route.test.ts
@@ -63,6 +63,8 @@ const DIGEST: DailyDigest = {
   briefingLead: "Blood pressure is holding steady.",
   line: "Blood pressure is holding steady.",
   worthALook: [],
+  justIn: null,
+  reactionLine: null,
 };
 
 const callGet = GET as unknown as (req: NextRequest) => Promise<Response>;
diff --git a/src/components/daily/__tests__/today-hero.test.tsx b/src/components/daily/__tests__/today-hero.test.tsx
index 5a7539b68..9d5949ab6 100644
--- a/src/components/daily/__tests__/today-hero.test.tsx
+++ b/src/components/daily/__tests__/today-hero.test.tsx
@@ -63,6 +63,8 @@ function digest(over: Partial<DailyDigest> = {}): DailyDigest {
     briefingLead: "Your week is trending steady.",
     line: "Your week is trending steady.",
     worthALook: [doseItem, syncItem],
+    justIn: null,
+    reactionLine: null,
     ...over,
   };
 }
diff --git a/src/components/daily/today-hero.tsx b/src/components/daily/today-hero.tsx
index 9550dd18d..8a19e25f0 100644
--- a/src/components/daily/today-hero.tsx
+++ b/src/components/daily/today-hero.tsx
@@ -37,6 +37,7 @@
 import Link from "next/link";
 import { Moon } from "lucide-react";
 
+import { useMounted } from "@/hooks/use-mounted";
 import { ScoreRing } from "@/components/insights/derived/score-ring";
 import type { ScoreBand } from "@/components/insights/derived/band-tokens";
 import { ProseBlocks } from "@/components/insights/prose-blocks";
@@ -62,8 +63,40 @@ function formatDelta(
   return t("daily.today.deltaVsBaseline", { delta: signed });
 }
 
+/**
+ * The "just in" chip's clock face.
+ *
+ * Formatted CLIENT-side, and only after mount. `justIn.at` crosses the wire as
+ * an ISO instant precisely so this stays a client concern: the server has no
+ * business rendering a local wall-clock time it would format under its OWN
+ * locale and timezone, and any such string would differ from the browser's on
+ * the hydration render — React #418, a class of bug this project has already
+ * paid for once.
+ *
+ * `undefined` locale lets the browser pick the user's own regional format
+ * (24-hour here, 12-hour there); the chip is a timestamp, not copy.
+ */
+function formatJustInTime(iso: string): string | null {
+  const at = new Date(iso);
+  if (Number.isNaN(at.getTime())) return null;
+  try {
+    return at.toLocaleTimeString(undefined, {
+      hour: "2-digit",
+      minute: "2-digit",
+    });
+  } catch {
+    return null;
+  }
+}
+
 export function TodayHero({ digest }: { digest: DailyDigest }) {
   const { t } = useTranslations();
+  // Gates ONLY the chip's time string — never the chip's presence. The hero
+  // itself is deliberately NOT mount-gated (v1.30.9: it is the LCP element and
+  // paints from the server-dehydrated digest on both the SSR and the hydration
+  // render). So the slot renders on both passes and the formatted time fills in
+  // on the first client re-render, keeping those two passes byte-identical.
+  const mounted = useMounted();
   const { keep, letGo } = useCoachCheckinAction();
   const dismissItem = usePriorityItemDismiss();
 
@@ -83,17 +116,25 @@ export function TodayHero({ digest }: { digest: DailyDigest }) {
 
   const hasScore = digest.score !== null;
   const hasItems = digest.worthALook.length > 0;
-  // The briefing lead is the warmest read; the deterministic `line` is the
-  // floor a keyless self-hoster still gets. Prefer the lead for the hero.
-  const lead = digest.briefingLead ?? digest.line;
+  // Lead precedence, warmest first: the day's reaction line REPLACES the
+  // briefing lead once something landed — it never appends as a second
+  // paragraph, so the hero stays exactly one lead line tall and nothing below
+  // it shifts. The briefing lead is the standing read; the deterministic
+  // `line` is the floor a keyless self-hoster still gets.
+  const lead = digest.reactionLine ?? digest.briefingLead ?? digest.line;
   const topSignal = digest.topSignal;
+  const justInTime = digest.justIn ? formatJustInTime(digest.justIn.at) : null;
 
   // Calm degrade (plan §3): a genuinely empty account — no score, no rail
   // items, and no cached briefing lead — surfaces nothing here. The tile
   // strip below carries its own "add your first reading" empty state, so a
   // second alarming empty card on the hero would be noise. The all-clear
   // state (score present, nothing needs attention) is handled inline below.
-  if (!hasScore && !hasItems && !digest.briefingLead) {
+  // A freshly-generated reaction line counts as content in its own right: an
+  // otherwise-bare account whose first reading just landed has something
+  // honest to say, and swallowing it here would hide the one moment this
+  // surface exists for.
+  if (!hasScore && !hasItems && !digest.briefingLead && !digest.reactionLine) {
     return null;
   }
 
@@ -184,17 +225,46 @@ export function TodayHero({ digest }: { digest: DailyDigest }) {
           </div>
         </div>
 
-        {/* Freshness note (plan §2.4) — provisional day, last night's sleep
-            not yet folded in. Muted, non-blocking, refreshes in place when
-            the morning job lands. */}
-        {digest.sleepPending ? (
-          <p
-            data-slot="today-hero-sleep-pending"
-            className="text-muted-foreground flex items-center gap-1.5 text-xs"
-          >
-            <Moon className="size-3.5 shrink-0" aria-hidden="true" />
-            {t("daily.today.sleepPending")}
-          </p>
+        {/* Meta row — the hero's quiet tier (UI-STANDARDS §text: `text-xs
+            text-muted-foreground` is the meta floor; never an accent, never an
+            opacity modifier). Holds the freshness note and the "just in" chip;
+            they can legitimately co-occur (a weight landed while last night's
+            sleep is still pending), so they share one wrapping row rather than
+            competing for the same slot. */}
+        {digest.sleepPending || digest.justIn ? (
+          <div className="text-muted-foreground flex flex-wrap items-center gap-x-3 gap-y-1 text-xs">
+            {/* Freshness note (plan §2.4) — provisional day, last night's
+                sleep not yet folded in. Muted, non-blocking, refreshes in
+                place when the morning job lands. */}
+            {digest.sleepPending ? (
+              <p
+                data-slot="today-hero-sleep-pending"
+                className="flex items-center gap-1.5"
+              >
+                <Moon className="size-3.5 shrink-0" aria-hidden="true" />
+                {t("daily.today.sleepPending")}
+              </p>
+            ) : null}
+
+            {/* The "just in" chip — a state change, not a notification. No
+                badge count, no accent, no animation: the record simply reads
+                differently on the next refresh, and this names why. It is
+                present for as long as the arrival is news (the server applies
+                the window, so the chip expires on a poll rather than on a
+                client timer) and carries the arrival's local time once the
+                client has mounted and can format it honestly. */}
+            {digest.justIn ? (
+              <p
+                data-slot="today-hero-just-in"
+                data-just-in-kind={digest.justIn.kind}
+                className="flex items-center gap-1.5"
+              >
+                {mounted && justInTime
+                  ? t("daily.today.justInAt", { time: justInTime })
+                  : t("daily.today.justIn")}
+              </p>
+            ) : null}
+          </div>
         ) : null}
 
         {/* Worth-a-look rail — S1's `PriorityCard`s, bounded 0–3. When the
diff --git a/src/lib/ai/ai-budgets.ts b/src/lib/ai/ai-budgets.ts
index c12be7d72..f2757f975 100644
--- a/src/lib/ai/ai-budgets.ts
+++ b/src/lib/ai/ai-budgets.ts
@@ -123,6 +123,18 @@ export const AI_BUDGETS = {
    */
   coachNudge: { temperature: 0.6, maxTokens: 160, timeoutMs: 9000 },
 
+  /**
+   * v1.31.0 — the arrival reaction line. ONE sentence replacing the Today
+   * hero's lead for the rest of the day, written at most once per arrival kind
+   * per local day (the `ArrivalReaction` unique row is the throttle). 220
+   * tokens is generous for a single sentence and leaves room for a model that
+   * warms up before it commits. Temperature between the reference surfaces and
+   * the conversational ones: the verdict must stay stable against the same
+   * evidence, but a line the user reads every day should not read as a
+   * template.
+   */
+  arrivalReaction: { temperature: 0.45, maxTokens: 220, timeoutMs: 12_000 },
+
   /**
    * Coach rolling-conversation summary worker — a compact summary of the
    * elided older turns. 200 tokens.
diff --git a/src/lib/ai/prompts/arrival-reaction.ts b/src/lib/ai/prompts/arrival-reaction.ts
new file mode 100644
index 000000000..830a96aa9
--- /dev/null
+++ b/src/lib/ai/prompts/arrival-reaction.ts
@@ -0,0 +1,99 @@
+/**
+ * The arrival reaction line — one sentence, written once per arrival kind per
+ * local day, that replaces the Today hero's standing lead for the rest of the
+ * day.
+ *
+ * This is the smallest AI surface in the product and it is deliberately the
+ * most constrained. It says ONE thing: something landed, and here is what it
+ * means against this person's own history. It is not a summary, not a plan,
+ * and not an assessment card — those surfaces exist and this one must not
+ * drift into them.
+ *
+ * LOCALE — the load-bearing detail. The body composes through
+ * `getBaseSystemPromptBody(locale)` and closes with `withOutputLanguage`,
+ * which is the SIX-locale path: German readers get the German body, and
+ * fr/es/it/pl get the English body plus a directive, in their own language,
+ * naming the language to write in. Do NOT reintroduce a local
+ * `locale === "de" ? "German" : "English"` here — that two-locale collapse is
+ * exactly the defect the base-system path was fixed to remove, and it silently
+ * ships English prose to four locales.
+ */
+import type { Locale } from "@/lib/i18n/config";
+import type { ArrivalKind } from "@/lib/arrivals/types";
+
+import { getBaseSystemPromptBody } from "./base-system";
+import { instructionLocale, withOutputLanguage } from "./output-language";
+
+/**
+ * The reaction contract, appended to the shared assessment base.
+ *
+ * Every clause here is a bound on FORM, not on content — the base prompt
+ * already owns the safety contract (no diagnosis, no prescription, earned
+ * encouragement, associations never causal). What this adds is the shape that
+ * makes a one-line reaction readable in a hero: verdict first, the number as
+ * support rather than as the opener, and a hard stop at one sentence.
+ */
+const REACTION_CONTRACT_EN = `SURFACE — THE ARRIVAL REACTION LINE:
+- Write EXACTLY ONE sentence. Not two. It renders as a single hero line and anything longer is truncated.
+- Lead with the MEANING, not the measurement. "A solid night, deeper than your recent stretch — 7 h 12 min behind it" reads correctly; "Your sleep is 7 h 12 min" does not. The figure is support; it may appear, but never as the opening clause.
+- Compare against THIS PERSON'S OWN recent baseline, which the evidence block carries already computed. State it; never recompute it, never invent a comparison the block does not contain.
+- Never exclamatory. No exclamation marks, no "great job", no congratulation the numbers did not earn. An unfavourable reading is named plainly and without alarm.
+- Never diagnostic and never prescriptive: no condition names, no risk levels, no dose or treatment suggestions, no training instructions.
+- When the evidence block is too thin to support a verdict, say so plainly in that one sentence. A manufactured verdict is worse than an honest "not much to go on yet".
+- Plain text only — no markdown, no quotation marks around the sentence, no emoji.`;
+
+const REACTION_CONTRACT_DE = `OBERFLÄCHE — DIE REAKTIONSZEILE ZUM DATENEINGANG:
+- Schreibe GENAU EINEN Satz. Nicht zwei. Er erscheint als einzelne Hero-Zeile; alles Längere wird abgeschnitten.
+- Führe mit der BEDEUTUNG, nicht mit dem Messwert. "Eine solide Nacht, tiefer als zuletzt — 7 h 12 min tragen sie" liest sich richtig; "Dein Schlaf beträgt 7 h 12 min" nicht. Die Zahl stützt; sie darf vorkommen, aber nie als einleitender Satzteil.
+- Vergleiche gegen die EIGENE jüngste Baseline dieser Person, die der Evidenzblock bereits fertig berechnet mitführt. Nenne sie; rechne sie nicht neu und erfinde keinen Vergleich, den der Block nicht enthält.
+- Nie ausrufend. Keine Ausrufezeichen, kein "super gemacht", kein Lob, das die Zahlen nicht hergeben. Ein ungünstiger Wert wird sachlich und ohne Alarm benannt.
+- Nie diagnostisch und nie verordnend: keine Krankheitsnamen, keine Risikostufen, keine Dosis- oder Therapievorschläge, keine Trainingsanweisungen.
+- Wenn der Evidenzblock zu dünn für ein Urteil ist, sage das in diesem einen Satz klar. Ein konstruiertes Urteil ist schlechter als ein ehrliches "dafür ist es noch zu wenig".
+- Nur Fließtext — kein Markdown, keine Anführungszeichen um den Satz, keine Emojis.`;
+
+export function getArrivalReactionSystemPrompt(locale: Locale): string {
+  // fr/es/it/pl compose the ENGLISH body — the base prompt names their own
+  // language and `withOutputLanguage` appends their directive last, so the
+  // language instruction is the final thing the model reads.
+  const contract =
+    instructionLocale(locale) === "en"
+      ? REACTION_CONTRACT_EN
+      : REACTION_CONTRACT_DE;
+
+  return withOutputLanguage(
+    `${getBaseSystemPromptBody(locale)}
+
+${contract}`,
+    locale,
+  );
+}
+
+/** What kind of arrival the line is reacting to, in the model's own terms. */
+const KIND_SUBJECT: Record<ArrivalKind, string> = {
+  sleep_night: "last night's completed sleep",
+  workout: "a workout the person just finished",
+  weight: "the first weight reading of the day",
+  blood_pressure: "a fresh blood-pressure reading",
+  labs_panel: "a new lab panel",
+};
+
+export interface ArrivalReactionPromptInput {
+  kind: ArrivalKind;
+  /**
+   * The deterministic, already-grounded evidence the digest read path
+   * computed. Passed verbatim — the model is never asked to derive a figure,
+   * only to say what the block already establishes.
+   */
+  evidence: string;
+}
+
+export function getArrivalReactionUserPrompt(
+  input: ArrivalReactionPromptInput,
+): string {
+  return `WHAT JUST LANDED: ${KIND_SUBJECT[input.kind]}.
+
+EVIDENCE BLOCK — everything below is already computed from this person's own record. Use only what is here; if it does not support a verdict, say so.
+${input.evidence}
+
+Write the one-sentence reaction line. Return only the sentence.`;
+}
diff --git a/src/lib/arrivals/reaction-line-shared.ts b/src/lib/arrivals/reaction-line-shared.ts
new file mode 100644
index 000000000..8c587a792
--- /dev/null
+++ b/src/lib/arrivals/reaction-line-shared.ts
@@ -0,0 +1,78 @@
+/**
+ * Generator-free enqueue contract for the `reaction-line-generate` queue.
+ *
+ * Same split as `emit-shared.ts`, and for the same reason: the spine's worker
+ * (`@/lib/jobs/data-arrival`) must be able to ENQUEUE a reaction line without
+ * importing the module that GENERATES one. The generator reaches a provider;
+ * the spine's central cost claim is that it structurally cannot. A shared
+ * queue-name-plus-payload module is what keeps both true at once, and the
+ * spine's module-graph guard (`data-arrival-provider-isolation.test.ts`)
+ * fails the moment this file grows an import that breaks it.
+ *
+ * Keep this module provider-free and worker-free.
+ */
+import { getGlobalBoss } from "@/lib/jobs/boss-instance";
+import { annotate } from "@/lib/logging/context";
+
+import type { ArrivalKind } from "./types";
+
+export const REACTION_LINE_QUEUE = "reaction-line-generate";
+
+/**
+ * The generation job's payload. It carries the row's identity, not its
+ * content: the worker re-reads the `ArrivalReaction` row it names, so a job
+ * that sat in the queue while the day moved on can still decide honestly
+ * whether the line is still wanted.
+ */
+export interface ReactionLineJob {
+  userId: string;
+  kind: ArrivalKind;
+  /** The user's profile-tz YYYY-MM-DD the marker is filed under. */
+  localDate: string;
+}
+
+/**
+ * Enqueue the day's single reaction-line generation for one arrival kind.
+ *
+ * The CALLER owns the throttle, and it is not a timer: the spine enqueues this
+ * only on the pass that freshly INSERTED the day's `ArrivalReaction` row, so
+ * the row's `@@unique([userId, kind, localDate])` constraint is what bounds
+ * the spend to one call per kind per local day. There is deliberately no
+ * second entry point — a surface that wants a line asks the spine for an
+ * arrival, it does not call the generator.
+ *
+ * The singleton key restates that claim at the queue level so a retried spine
+ * job cannot stack a second generation behind the first.
+ *
+ * Never throws. A queue that is not there means no line, and no line is a
+ * fully-supported state.
+ */
+export async function enqueueReactionLine(job: ReactionLineJob): Promise<void> {
+  try {
+    const boss = getGlobalBoss();
+    if (!boss) {
+      annotate({
+        action: { name: "arrival.reaction_line.skipped" },
+        meta: { reason: "no_boss", kind: job.kind },
+      });
+      return;
+    }
+
+    await boss.send(REACTION_LINE_QUEUE, job, {
+      singletonKey: `reaction-line:${job.userId}:${job.kind}:${job.localDate}`,
+      // The LLM retry policy, not the spine's: a provider hiccup is worth one
+      // patient retry, and a second failure leaves the row line-less — which
+      // is a first-class state, not an error to keep chasing.
+      retryLimit: 1,
+      retryDelay: 120,
+      retryBackoff: true,
+    });
+
+    annotate({
+      action: { name: "arrival.reaction_line.enqueued" },
+      meta: { kind: job.kind, local_date: job.localDate },
+    });
+  } catch {
+    // The data landed and the marker is written; the sentence is garnish.
+  }
+}
diff --git a/src/lib/daily/__tests__/daily-briefing-push.test.ts b/src/lib/daily/__tests__/daily-briefing-push.test.ts
index 6aae8c602..8ef31e2b4 100644
--- a/src/lib/daily/__tests__/daily-briefing-push.test.ts
+++ b/src/lib/daily/__tests__/daily-briefing-push.test.ts
@@ -34,6 +34,8 @@ function makeDigest(over: Partial<DailyDigest> = {}): DailyDigest {
     briefingLead: "Sleep looked solid last night.",
     line: "Sleep looked solid last night.",
     worthALook: [],
+    justIn: null,
+    reactionLine: null,
     ...over,
   };
 }
diff --git a/src/lib/daily/__tests__/load-digest.test.ts b/src/lib/daily/__tests__/load-digest.test.ts
index 5e775572c..f6c2df61a 100644
--- a/src/lib/daily/__tests__/load-digest.test.ts
+++ b/src/lib/daily/__tests__/load-digest.test.ts
@@ -19,6 +19,7 @@ vi.mock("@/lib/db", () => ({
     ecgRecording: { findFirst: vi.fn().mockResolvedValue(null) },
     dismissedPriorityItem: { findMany: vi.fn().mockResolvedValue([]) },
     personalRecord: { findMany: vi.fn().mockResolvedValue([]) },
+    arrivalReaction: { findMany: vi.fn().mockResolvedValue([]) },
   },
 }));
 
diff --git a/src/lib/daily/digest.ts b/src/lib/daily/digest.ts
index 8fe0ff7b4..7f93ee277 100644
--- a/src/lib/daily/digest.ts
+++ b/src/lib/daily/digest.ts
@@ -20,6 +20,7 @@
  * populate the same two fields the DTO already carries, so no consumer changes.
  */
 import type { DailyBriefing, DailyBriefingSignal } from "@/lib/ai/schema";
+import type { ArrivalKind } from "@/lib/arrivals/types";
 import type { MedsTodayBlock } from "@/lib/dashboard/meds-today";
 import type { ModuleKey } from "@/lib/modules/registry";
 import type { ServerTranslator } from "@/lib/i18n/server-translator";
@@ -151,6 +152,32 @@ export interface DailyDigestCoachPlan {
   planText: string | null;
 }
 
+/**
+ * A day's arrival marker, as the IO seam read it off `ArrivalReaction`.
+ *
+ * One row per (user, kind, local date) — the spine's unique claim. The builder
+ * picks the NEWEST of them for the "just in" chip and takes its reaction line;
+ * it never sees more than the day's own rows, and it never reads a row it did
+ * not ask for.
+ */
+export interface DailyDigestArrival {
+  kind: ArrivalKind;
+  /** Timestamp of the newest sample that triggered this arrival. */
+  occurredAt: Date;
+  /** Decrypted reaction line, or null when none was ever generated. */
+  line: string | null;
+}
+
+/**
+ * How long an arrival stays NEWS.
+ *
+ * Past this the record is simply current — the reading is still today's, but
+ * announcing it is no longer telling the user anything they don't know. The
+ * chip disappears on its own; the reaction LINE does not (see below), because
+ * the sentence is the day's read, not a notification.
+ */
+export const JUST_IN_WINDOW_MS = 3 * 60 * 60 * 1000;
+
 /** The fully-resolved, IO-free input the composer folds into a digest. */
 export interface DailyDigestInput {
   now: Date;
@@ -203,6 +230,12 @@ export interface DailyDigestInput {
    * never rendered with its actions suppressed.
    */
   dismissedItemKeys: ReadonlySet<string>;
+  /**
+   * Today's arrival markers (`ArrivalReaction` rows for `todayLocalDate`), in
+   * any order. Optional so a consumer that predates the arrival spine stays
+   * valid; the builder treats a missing value as "nothing landed today".
+   */
+  arrivals?: readonly DailyDigestArrival[];
 }
 
 export interface DailyDigest {
@@ -226,6 +259,26 @@ export interface DailyDigest {
   line: string;
   /** Bounded 0–3 rail items, never padded. */
   worthALook: PriorityItem[];
+  /**
+   * The day's newest arrival while it is still news (< `JUST_IN_WINDOW_MS`
+   * old), else null. Drives the hero's calm "just in" chip.
+   *
+   * `at` crosses the wire as an ISO-8601 string and is formatted CLIENT-side —
+   * a server-formatted local time would differ from the client's render and
+   * produce a hydration mismatch (React #418).
+   */
+  justIn: { kind: ArrivalKind; at: string } | null;
+  /**
+   * The generated reaction line for the day's newest arrival, or null.
+   *
+   * Deliberately NOT gated on the just-in window: the chip is the "this just
+   * landed" moment and expires, while the sentence is the day's read and
+   * stands for the rest of the local day. Null whenever no line was generated
+   * — no provider, no consent, budget exhausted, or the generation failed —
+   * in which case the surface falls back to the deterministic lead. The
+   * sentence is garnish; its absence degrades nothing.
+   */
+  reactionLine: string | null;
 }
 
 /** First sentence of a paragraph, trimmed; null when empty. */
@@ -647,6 +700,33 @@ export function buildDailyDigest(
   const topSignal = input.briefing?.signalsOfDay?.[0] ?? null;
   const briefingLead = firstSentence(input.briefing?.paragraph);
 
+  // The day's newest arrival drives both reaction fields, but on two different
+  // clocks: the chip expires with the news, the sentence stands for the day.
+  // Reducing rather than sorting keeps the composer allocation-free and total
+  // over an empty list.
+  const newestArrival = (
+    input.arrivals ?? []
+  ).reduce<DailyDigestArrival | null>(
+    (newest, candidate) =>
+      newest === null || candidate.occurredAt > newest.occurredAt
+        ? candidate
+        : newest,
+    null,
+  );
+  const arrivalAgeMs = newestArrival
+    ? input.now.getTime() - newestArrival.occurredAt.getTime()
+    : null;
+  const justIn =
+    newestArrival && arrivalAgeMs !== null && arrivalAgeMs < JUST_IN_WINDOW_MS
+      ? {
+          kind: newestArrival.kind,
+          at: newestArrival.occurredAt.toISOString(),
+        }
+      : null;
+  // An empty or whitespace-only line is treated as absent rather than shipped
+  // as a blank lead — a degraded generation must fall through to the floor.
+  const reactionLine = newestArrival?.line?.trim() || null;
+
   // Priority order: a due or overdue dose is the most time-sensitive daily
   // action, a broken sync next, then the calm coach check-in, a preventive
   // check-up least urgent. Bounded to 3 — a check-in the cap crowds out
@@ -717,5 +797,7 @@ export function buildDailyDigest(
     briefingLead,
     line: composeLine(briefingLead, topSignal, input.score, t),
     worthALook: visible.slice(0, MAX_WORTH_A_LOOK),
+    justIn,
+    reactionLine,
   };
 }
diff --git a/src/lib/daily/load-digest.ts b/src/lib/daily/load-digest.ts
index 9464470e9..1c683d6e1 100644
--- a/src/lib/daily/load-digest.ts
+++ b/src/lib/daily/load-digest.ts
@@ -24,9 +24,11 @@ import { decryptFromBytes } from "@/lib/ai/coach/bytes-codec";
 import { userDayKey } from "@/lib/tz/format";
 import { cachedSwr, caches, type ServerCache } from "@/lib/cache/server-cache";
 import { DASHBOARD_REFETCH_INTERVAL_MS } from "@/lib/queries/refetch-interval";
+import { isArrivalKind } from "@/lib/arrivals/types";
 import {
   buildDailyDigest,
   type DailyDigest,
+  type DailyDigestArrival,
   type DailyDigestCoachPlan,
   type DailyDigestEcg,
   type DailyDigestPreventiveDue,
@@ -239,10 +241,50 @@ function resolveLocale(locale: string | null | undefined): Locale {
     : defaultLocale;
 }
 
+/**
+ * Today's arrival markers, decrypted fault-isolated.
+ *
+ * One indexed read on `[userId, localDate]` — the exact shape of the model's
+ * `@@index`, and at most one row per arrival kind, so the result is bounded by
+ * the closed `ARRIVAL_KINDS` enum rather than by anything the user can grow.
+ *
+ * A line that fails to decrypt (a key rotated out from under the row) yields a
+ * null line, never a throw: the digest is a hot, must-not-fail path, and the
+ * marker itself — which is what actually drives the "just in" chip — survives
+ * a lost sentence intact. Same discipline as `toCoachPlanCandidate` above.
+ */
+function toDigestArrival(row: {
+  kind: string;
+  occurredAt: Date;
+  lineEncrypted: Uint8Array | null;
+  generatedAt: Date | null;
+}): DailyDigestArrival | null {
+  // A kind this build does not know about (a row written by a newer version)
+  // is dropped rather than widened — the DTO's kind union is closed.
+  if (!isArrivalKind(row.kind)) return null;
+
+  let line: string | null = null;
+  // The ciphertext rides only once the generation actually COMMITTED. A row
+  // mid-generation carries no `generatedAt`, and its line must not surface.
+  if (row.generatedAt !== null && row.lineEncrypted !== null) {
+    try {
+      line = decryptFromBytes(row.lineEncrypted);
+    } catch {
+      line = null;
+    }
+  }
+
+  return { kind: row.kind, occurredAt: row.occurredAt, line };
+}
+
 export async function loadDailyDigest(
   user: User,
   now: Date = new Date(),
 ): Promise<DailyDigest> {
+  // Computed before the fan-out because the arrival read is keyed on it. Pure
+  // (a tz format of `now`), so hoisting it costs nothing.
+  const todayLocalDate = userDayKey(now, user.timezone);
+
   const [
     { body: snapshot, locale },
     modules,
@@ -250,6 +292,7 @@ export async function loadDailyDigest(
     dueReminders,
     planRows,
     ecgRow,
+    arrivalRows,
   ] = await Promise.all([
     readDashboardSnapshotCached(user),
     resolveModuleMap(user.id),
@@ -303,6 +346,18 @@ export async function loadDailyDigest(
       orderBy: { recordedAt: "desc" },
       select: { recordedAt: true, rhythmClassification: true },
     }),
+    // The arrival spine's markers for the user's CURRENT local day. At most
+    // one row per arrival kind by the model's unique constraint, so this is a
+    // bounded indexed read, not a scan.
+    prisma.arrivalReaction.findMany({
+      where: { userId: user.id, localDate: todayLocalDate },
+      select: {
+        kind: true,
+        occurredAt: true,
+        lineEncrypted: true,
+        generatedAt: true,
+      },
+    }),
   ]);
 
   const score: DailyDigestScore | null = snapshot.healthScore
@@ -321,7 +376,6 @@ export async function loadDailyDigest(
   // local date (profile tz). Read fresh off the row here, so it flips the
   // instant the refresh job runs — ahead of the snapshot cache that feeds
   // `sleepLastSeenDaysAgo`.
-  const todayLocalDate = userDayKey(now, user.timezone);
   const morningRefreshedToday =
     user.morningDigestRefreshedOn !== null &&
     user.morningDigestRefreshedOn === todayLocalDate;
@@ -423,6 +477,9 @@ export async function loadDailyDigest(
       latestEcg,
       todayLocalDate,
       dismissedItemKeys,
+      arrivals: arrivalRows
+        .map(toDigestArrival)
+        .filter((a): a is DailyDigestArrival => a !== null),
     },
     t,
   );
@@ -440,6 +497,8 @@ export async function loadDailyDigest(
       daily_digest_has_milestone: digest.worthALook.some(
         (i) => i.kind === "milestone",
       ),
+      daily_digest_just_in_kind: digest.justIn?.kind ?? null,
+      daily_digest_has_reaction_line: digest.reactionLine !== null,
     },
   });
 
diff --git a/src/lib/jobs/data-arrival.ts b/src/lib/jobs/data-arrival.ts
index 67582c091..c4f3d33b5 100644
--- a/src/lib/jobs/data-arrival.ts
+++ b/src/lib/jobs/data-arrival.ts
@@ -36,6 +36,7 @@ import { annotate } from "@/lib/logging/context";
 import { withBackgroundEvent } from "@/lib/logging/background";
 
 import { DATA_ARRIVAL_QUEUE } from "@/lib/arrivals/emit-shared";
+import { enqueueReactionLine } from "@/lib/arrivals/reaction-line-shared";
 import { isArrivalKind, type DataArrival } from "@/lib/arrivals/types";
 
 import { getWorkerPrisma, workerLog } from "./reminder/shared";
@@ -142,9 +143,16 @@ export async function runDataArrival(
   }
 
   if (claimed) {
-    // DISPATCH POINT — the day's single reaction line consumes this.
-    // Gated on `claimed` precisely BECAUSE the unique row is the throttle:
-    // there is no code path to a second generation for this kind today.
+    // The day's single reaction line. Gated on `claimed` precisely BECAUSE the
+    // unique row is the throttle: this is the only pass that can have won the
+    // claim, so there is no code path to a second generation for this kind
+    // today. The enqueue helper is provider-free by construction (see its
+    // docblock and the module-graph guard) — this worker still spends nothing.
+    await enqueueReactionLine({
+      userId: arrival.userId,
+      kind: arrival.kind,
+      localDate: arrival.localDate,
+    });
     actions.push("line_pending");
   }
 
diff --git a/src/lib/jobs/reaction-line.ts b/src/lib/jobs/reaction-line.ts
new file mode 100644
index 000000000..eef7925af
--- /dev/null
+++ b/src/lib/jobs/reaction-line.ts
@@ -0,0 +1,308 @@
+/**
+ * The `reaction-line-generate` worker — the day's single sentence about what
+ * just landed.
+ *
+ * This is the ONE provider call the arrival spine can cause, and the whole
+ * design of the surface is arranged so that call is bounded before it is made:
+ *
+ *   - The THROTTLE is a durable unique row, not a timer. The spine enqueues
+ *     this only on the pass that freshly INSERTED today's `ArrivalReaction`
+ *     for the kind (`data-arrival.ts`, the `claimed` branch), and this worker
+ *     re-checks `generatedAt` before spending anything. Both ends of that
+ *     claim are the same `@@unique([userId, kind, localDate])` constraint, so
+ *     there is no code path to a second call for a kind on a day — not a
+ *     racing spine job, not a retry, not a hand-sent job.
+ *   - The SPEND is reserved before the call and reconciled on EVERY exit,
+ *     including each failure path. A provider that times out still burned
+ *     upstream tokens; a reservation that is never reconciled is a silent
+ *     over-charge against the user's own daily ceiling.
+ *   - The FLOOR is complete without any of this. No provider, no consent, an
+ *     exhausted budget, a refused output, a dead network — every one of them
+ *     leaves the row line-less, and a line-less row still drives the "just in"
+ *     chip and the provisional→final flip. The reaction is a state change; the
+ *     sentence is garnish. `reaction-line-degradation.test.ts` holds that line.
+ *
+ * The grounding is deliberately the digest itself: it is already cached,
+ * already deterministic, already the thing the surface will render the line
+ * next to, and reading it costs no new query path. A line grounded in a
+ * DIFFERENT snapshot than the one on screen is how a surface starts
+ * contradicting itself.
+ */
+import type { Job } from "pg-boss";
+
+import { prisma } from "@/lib/db";
+import { annotate } from "@/lib/logging/context";
+import { withBackgroundEvent } from "@/lib/logging/background";
+import { resolveProviderChain } from "@/lib/ai/provider";
+import {
+  chainRequiresServerManagedConsent,
+  hasActiveConsentForSurface,
+} from "@/lib/ai/consent-guard";
+import {
+  buildDateKey,
+  reconcileSpend,
+  reserveBudget,
+  resolveDailyCap,
+} from "@/lib/ai/coach/budget";
+import { AI_BUDGETS } from "@/lib/ai/ai-budgets";
+import { singleUserTurn } from "@/lib/ai/types";
+import { screenCoachReply } from "@/lib/ai/coach/outbound-guard";
+import { encryptToBytes } from "@/lib/ai/coach/bytes-codec";
+import { defaultLocale, locales, type Locale } from "@/lib/i18n/config";
+import { loadDailyDigest } from "@/lib/daily/load-digest";
+import {
+  getArrivalReactionSystemPrompt,
+  getArrivalReactionUserPrompt,
+} from "@/lib/ai/prompts/arrival-reaction";
+import {
+  REACTION_LINE_QUEUE,
+  type ReactionLineJob,
+} from "@/lib/arrivals/reaction-line-shared";
+
+import { workerLog } from "./reminder/shared";
+
+export { REACTION_LINE_QUEUE };
+
+/** Upstream timeout. A hero line is not worth holding a worker slot for long. */
+export const REACTION_LINE_TIMEOUT_MS = 12_000;
+
+/**
+ * Hard ceiling on a shippable line. The contract asks for one sentence; a
+ * model that returns a paragraph has not followed it, and clamping mid-thought
+ * would ship a truncated verdict. Reject and keep the deterministic lead.
+ */
+export const REACTION_LINE_MAX_CHARS = 240;
+
+/**
+ * Tokens reserved per call.
+ *
+ * Sized to the whole call, not the output ceiling: the base assessment system
+ * prompt plus a compact evidence block plus the 220-token output. Reserving
+ * only the output would let a day's reactions spend materially more than they
+ * booked against the user's daily cap — the reconcile corrects the number
+ * afterwards, but the CAP check happens at reservation time.
+ */
+export const ARRIVAL_REACTION_RESERVE_TOKENS = 1_400;
+
+export type ReactionLineOutcome =
+  { status: "skipped"; reason: string } | { status: "generated" };
+
+function resolveLocale(locale: string | null | undefined): Locale {
+  return locales.includes(locale as Locale)
+    ? (locale as Locale)
+    : defaultLocale;
+}
+
+/**
+ * Normalise the model's output into a shippable sentence, or null.
+ *
+ * Rejects rather than repairs: a line that broke the shape broke the contract,
+ * and the deterministic lead it would replace is already good.
+ */
+export function sanitiseReactionLine(
+  raw: string,
+  locale: Locale,
+): string | null {
+  let text = (raw ?? "").trim();
+  if (!text) return null;
+  text = text
+    .replace(/^["“”'`]+/, "")
+    .replace(/["“”'`]+$/, "")
+    .trim()
+    .replace(/\s+/g, " ");
+  if (!text) return null;
+  if (text.length > REACTION_LINE_MAX_CHARS) return null;
+  // The same outbound content fence the Coach reply path runs — a dose
+  // prescription or a fabricated risk score never reaches the hero.
+  if (screenCoachReply(text, locale).block) return null;
+  return text;
+}
+
+/**
+ * The deterministic evidence block. Built from the ALREADY-COMPUTED digest —
+ * no figure here is derived in this module, which is what keeps the line
+ * grounded in the same numbers the surface is rendering.
+ */
+function buildEvidence(digest: {
+  score: { value: number; band: string; delta: number | null } | null;
+  topSignal: { headline: string; delta: string | null } | null;
+  briefingLead: string | null;
+}): string {
+  const parts: string[] = [];
+  if (digest.score) {
+    const delta =
+      digest.score.delta === null
+        ? "no baseline comparison available"
+        : `${digest.score.delta > 0 ? "+" : ""}${Math.round(digest.score.delta)} vs their baseline`;
+    parts.push(
+      `- Health score: ${Math.round(digest.score.value)} (${digest.score.band}), ${delta}.`,
+    );
+  }
+  if (digest.topSignal) {
+    parts.push(
+      `- Today's leading signal: ${digest.topSignal.headline}${
+        digest.topSignal.delta ? ` (${digest.topSignal.delta})` : ""
+      }.`,
+    );
+  }
+  if (digest.briefingLead) {
+    parts.push(`- The day's standing read: ${digest.briefingLead}`);
+  }
+  return parts.length > 0
+    ? parts.join("\n")
+    : "- (No computed comparison is available for this person yet.)";
+}
+
+/**
+ * Generate and persist one reaction line.
+ *
+ * Every refusal RETURNS a status rather than throwing — the discipline the
+ * spine's worker documents at length. A ceiling that does not move until the
+ * local day rolls over must never be retried against.
+ */
+export async function runReactionLine(
+  job: ReactionLineJob,
+): Promise<ReactionLineOutcome> {
+  const row = await prisma.arrivalReaction.findUnique({
+    where: {
+      userId_kind_localDate: {
+        userId: job.userId,
+        kind: job.kind,
+        localDate: job.localDate,
+      },
+    },
+    select: { id: true, generatedAt: true },
+  });
+
+  // The marker is gone (retention swept it, or the account was deleted) or a
+  // line already committed. Either way there is nothing left to write, and the
+  // unique row having a `generatedAt` IS the once-per-kind-per-day claim.
+  if (!row) return { status: "skipped", reason: "no_marker" };
+  if (row.generatedAt !== null) {
+    return { status: "skipped", reason: "already_generated" };
+  }
+
+  // The whole row: the locale decides the prompt, and `loadDailyDigest` takes
+  // a `User` (it reads the timezone and the morning-refresh marker off it), so
+  // one read serves both rather than two.
+  const user = await prisma.user.findUnique({ where: { id: job.userId } });
+  if (!user) return { status: "skipped", reason: "no_user" };
+
+  const locale = resolveLocale(user.locale);
+
+  const chain = await resolveProviderChain(job.userId);
+  // A provider-less install is the DEFAULT self-hosted shape, not an error.
+  if (chain.length === 0) return { status: "skipped", reason: "no_provider" };
+
+  // Consent gate before the reservation, so a user without a receipt never
+  // spends a token. This tick is unattended, so it carries the same receipt
+  // requirement as the interactive surfaces. BYOK / local / ChatGPT-OAuth
+  // chains are the user's own egress and stay ungated.
+  if (
+    chainRequiresServerManagedConsent(chain) &&
+    !(await hasActiveConsentForSurface(job.userId, "insights"))
+  ) {
+    return { status: "skipped", reason: "consent_required" };
+  }
+
+  const budget = AI_BUDGETS.arrivalReaction;
+  const maxTokens = budget.maxTokens ?? 220;
+  const dateKey = buildDateKey();
+  const reservation = await reserveBudget(
+    job.userId,
+    // Reserve the documented ceiling for this surface, not the output cap
+    // alone: the reservation has to cover the prompt the call actually sends,
+    // or a day of these under-reports its own spend against the user's cap.
+    ARRIVAL_REACTION_RESERVE_TOKENS,
+    dateKey,
+    resolveDailyCap(chain),
+  );
+  if (!reservation.allowed) {
+    return { status: "skipped", reason: "budget_exceeded" };
+  }
+
+  // From here every exit MUST reconcile — the reservation is already on the
+  // user's ledger.
+  let line: string | null = null;
+  try {
+    // The digest is the grounding AND the thing the line will sit inside.
+    const digest = await loadDailyDigest(user);
+
+    const result = await chain[0].instance.generateCompletion(
+      singleUserTurn({
+        system: getArrivalReactionSystemPrompt(locale),
+        user: getArrivalReactionUserPrompt({
+          kind: job.kind,
+          evidence: buildEvidence(digest),
+        }),
+        temperature: budget.temperature,
+        maxTokens,
+        timeoutMs: REACTION_LINE_TIMEOUT_MS,
+        signal: AbortSignal.timeout(REACTION_LINE_TIMEOUT_MS + 1_000),
+      }),
+    );
+
+    await reconcileSpend(
+      job.userId,
+      reservation.reserved,
+      result.tokensUsed ?? 0,
+      dateKey,
+      result.cachedInputTokens ?? 0,
+    ).catch(() => {});
+
+    line = sanitiseReactionLine(result.content, locale);
+  } catch (err) {
+    // Timeout / network / provider / grounding failure. Reconcile against a
+    // zero actual so the unspent reservation is returned, then degrade.
+    await reconcileSpend(job.userId, reservation.reserved, 0, dateKey).catch(
+      () => {},
+    );
+    workerLog("error", "[reaction-line] generation failed", err);
+    return { status: "skipped", reason: "provider_failed" };
+  }
+
+  if (!line) return { status: "skipped", reason: "unusable_output" };
+
+  // Commit. `generatedAt` and the ciphertext land together and are read
+  // together (`load-digest.ts` requires both), so a half-written row can never
+  // surface a line.
+  await prisma.arrivalReaction.update({
+    where: { id: row.id },
+    data: { lineEncrypted: encryptToBytes(line), generatedAt: new Date() },
+  });
+
+  return { status: "generated" };
+}
+
+export async function handleReactionLine(
+  jobs: Job<ReactionLineJob>[],
+): Promise<void> {
+  await withBackgroundEvent("job.reaction_line", async (evt) => {
+    for (const job of jobs) {
+      try {
+        const outcome = await runReactionLine(job.data);
+
+        if (outcome.status === "skipped") {
+          annotate({
+            action: { name: "arrival.reaction_line.skipped" },
+            meta: { reason: outcome.reason, kind: job.data.kind },
+          });
+          evt.addMeta("reaction_line", `skipped:${outcome.reason}`);
+          continue;
+        }
+
+        annotate({
+          action: { name: "arrival.reaction_line.generated" },
+          meta: { kind: job.data.kind, local_date: job.data.localDate },
+        });
+        evt.addMeta("reaction_line", "generated");
+      } catch (err) {
+        // Only a genuine transient fault reaches here — every business refusal
+        // returned a status. Let the queue's single retry apply; the
+        // `generatedAt` check makes the retry idempotent.
+        workerLog("error", "[reaction-line] pass failed", err);
+        throw err;
+      }
+    }
+  });
+}
diff --git a/src/lib/jobs/reminder/register-status.ts b/src/lib/jobs/reminder/register-status.ts
index c8cab6683..831b6f70a 100644
--- a/src/lib/jobs/reminder/register-status.ts
+++ b/src/lib/jobs/reminder/register-status.ts
@@ -30,6 +30,11 @@ import {
   type MorningDigestRefreshPayload,
 } from "@/lib/jobs/morning-digest-refresh";
 import { DATA_ARRIVAL_QUEUE, handleDataArrival } from "@/lib/jobs/data-arrival";
+import {
+  REACTION_LINE_QUEUE,
+  handleReactionLine,
+} from "@/lib/jobs/reaction-line";
+import type { ReactionLineJob } from "@/lib/arrivals/reaction-line-shared";
 import type { DataArrival } from "@/lib/arrivals/types";
 import {
   DAILY_BRIEFING_QUEUE,
@@ -179,6 +184,10 @@ const allQueues = [
   // this entry pg-boss never provisions the queue and every emit silently
   // drops (the v1.4.37 dead-queue class).
   DATA_ARRIVAL_QUEUE,
+  // v1.31.0 — the day's single arrival reaction line. Send-only, enqueued by
+  // the spine worker on the pass that claimed the day's marker. Without this
+  // entry pg-boss never provisions the queue and every enqueue silently drops.
+  REACTION_LINE_QUEUE,
   // v1.10.0 — computed scores (WX-C / WX-E). Nightly Recovery / Stress /
   // Strain compute + store. The queue MUST be registered here or pg-boss
   // never provisions it and the nightly schedule silently never fires.
@@ -302,6 +311,16 @@ const queuePolicies: QueuePolicyTable = {
   // id and DOES pass `singletonSeconds`, so it is constrained by pg-boss's
   // `job_i4` index regardless of this policy. Both shapes coexist on one
   // queue safely: they populate different columns.
+  // The reaction line's key is `reaction-line:<user>:<kind>:<localDate>` — the
+  // same day-scoped shape, and for the same reason: a wall-clock window cannot
+  // express a user's local date. `exclusive` is what makes the key real, and it
+  // is the queue-level restatement of the durable claim the worker re-checks
+  // (`generatedAt`) before it spends anything.
+  [REACTION_LINE_QUEUE]: {
+    policy: "exclusive",
+    reason:
+      "Day-scoped per-kind keys carry the user's local date; under standard they coalesce nothing and a retried spine job could stack a second provider call behind the first.",
+  },
   [DATA_ARRIVAL_QUEUE]: {
     policy: "exclusive",
     reason:
@@ -532,6 +551,14 @@ export async function registerStatusQueues(
     { localConcurrency: 1 },
     handleDataArrival,
   );
+  // v1.31.0 — the arrival reaction line. Single-flight: this is the spine's
+  // ONE provider call, and a second concurrent slot would only race the same
+  // durable `generatedAt` claim exactly one of them can win.
+  await boss.work<ReactionLineJob>(
+    REACTION_LINE_QUEUE,
+    { localConcurrency: 1 },
+    handleReactionLine,
+  );
   // S5 — daily-briefing fallback slot. Single-flight; the `push_attempts`
   // frequency cap makes an overlapping tick a no-op (a second same-day attempt
   // is suppressed), and the tick only loads a digest for opted-in users at
diff --git a/src/lib/openapi/routes/daily.ts b/src/lib/openapi/routes/daily.ts
index 06c791f99..72213df18 100644
--- a/src/lib/openapi/routes/daily.ts
+++ b/src/lib/openapi/routes/daily.ts
@@ -11,6 +11,7 @@
 import { z } from "zod/v4";
 import type { ZodOpenApiObject } from "zod-openapi";
 
+import { ARRIVAL_KINDS } from "@/lib/arrivals/types";
 import { PRIORITY_ITEM_KINDS } from "@/lib/daily/priority-item";
 import { dismissPriorityItemSchema } from "@/lib/validations/daily";
 import { dataEnvelope, moduleDisabledResponse, stdResponses } from "./shared";
@@ -95,6 +96,27 @@ const dailyDigestResponse = z
     worthALook: z
       .array(priorityItemSchema)
       .describe("Bounded 0–3 rail items, never padded."),
+    justIn: z
+      .object({
+        kind: z
+          .enum([...ARRIVAL_KINDS])
+          .describe("Closed arrival kind that landed."),
+        at: z
+          .string()
+          .describe(
+            "ISO-8601 instant of the newest sample. NEVER pre-formatted server-side — the client formats it in its own locale and timezone.",
+          ),
+      })
+      .nullable()
+      .describe(
+        "The day's newest data arrival while it is still news (under three hours old), else null. Additive since v1.31.0.",
+      ),
+    reactionLine: z
+      .string()
+      .nullable()
+      .describe(
+        "One-sentence generated reaction to that arrival, standing for the rest of the local day. Null whenever no line was generated (no provider, no consent, budget exhausted, or generation failed) — consumers fall back to `briefingLead` / `line`. Additive since v1.31.0.",
+      ),
   })
   .meta({
     id: "DailyDigest",