diff --git a/src/lib/components/MicroSteps.svelte b/src/lib/components/MicroSteps.svelte
index 9d05fa3..f9ff7b3 100644
--- a/src/lib/components/MicroSteps.svelte
+++ b/src/lib/components/MicroSteps.svelte
@@ -1,10 +1,14 @@
 <script lang="ts">
   import { invoke } from '@tauri-apps/api/core';
-  import { ListTree, Check, Timer, Loader2, ThumbsUp, ThumbsDown, Pencil } from 'lucide-svelte';
+  import { ListTree, Check, Timer, Loader2, ThumbsUp, ThumbsDown, Pencil, X } from 'lucide-svelte';
   import { profilesStore } from '$lib/stores/profiles.svelte.ts';
-  import { replaceTaskFromDto } from '$lib/stores/page.svelte.js';
+  import { replaceTaskFromDto, settings } from '$lib/stores/page.svelte.js';
   import type { TaskDto } from '$lib/types/app.ts';
   import SpeakerButton from '$lib/components/SpeakerButton.svelte';
+  import {
+    recordActivity,
+    shouldShowReorientBanner,
+  } from '$lib/utils/microstepActivity.js';
 
   let { parentTaskId, parentTaskText = '', reduceMotion = false } = $props();
 
@@ -35,6 +39,52 @@
   // a faster second save that already committed.
   let saveToken = $state<Record<string, number>>({});
 
+  // B3.4 — "Where was I?" re-orientation banner. Shown when the user
+  // re-opens a parent task whose decomposition has been idle ≥30 min
+  // OR sat across a session boundary (most recent app launch is after
+  // the parent's last activity stamp). Banner self-dismisses on first
+  // interaction (any check/edit/click) or via the explicit X. Never
+  // shown when the list is all-done or all-pending.
+  let reorientShown = $state(false);
+  let reorientDismissed = $state(false);
+
+  const lastDoneStep = $derived(
+    [...subtasks].reverse().find((s) => s.done) ?? null,
+  );
+  const nextPendingStep = $derived(subtasks.find((s) => !s.done) ?? null);
+
+  const reorientBannerText = $derived(
+    lastDoneStep && nextPendingStep
+      ? `Last completed: ${lastDoneStep.text}. Next: ${nextPendingStep.text}.`
+      : '',
+  );
+
+  function dismissReorient() {
+    if (reorientShown) {
+      reorientShown = false;
+      reorientDismissed = true;
+    }
+  }
+
+  // Evaluate whether to surface the banner. Called once after each
+  // subtask load — the gate reads the persisted last-activity map and
+  // the most recent app-launch stamp; both are stable for the duration
+  // of this mount, so we don't need to re-evaluate on every check.
+  function maybeShowReorientBanner() {
+    if (reorientDismissed) return;
+    if (!parentTaskId) return;
+    if (subtasks.length === 0) return;
+    if (!lastDoneStep || !nextPendingStep) return;
+    if (
+      shouldShowReorientBanner({
+        parentTaskId,
+        lastLaunchAt: settings.lastLaunchAt,
+      })
+    ) {
+      reorientShown = true;
+    }
+  }
+
   async function loadSubtasks() {
     loading = true;
     error = '';
@@ -45,6 +95,11 @@
     } finally {
       loading = false;
     }
+    // B3.4 — evaluate the re-orientation gate once after the steps
+    // land. Reads the persisted last-activity map plus the stable
+    // settings.lastLaunchAt stamp; both will not change during this
+    // mount, so a single evaluation is sufficient.
+    maybeShowReorientBanner();
   }
 
   async function decompose() {
@@ -55,6 +110,10 @@
         parentTaskId,
         profileId: profilesStore.activeProfileId,
       });
+      // B3.4 — fresh decomposition counts as activity for the
+      // re-orientation banner (so opening this same task in 30+ min
+      // can surface the banner).
+      recordActivity(parentTaskId);
       // Phase 6 nudge-bus signal. The bus schedules a 15-min idle
       // check on this parent task id — if no step or the task itself
       // is completed in that window, a gentle "still with that one?"
@@ -72,6 +131,10 @@
   }
 
   async function checkStep(subtaskId: string) {
+    // B3.4 — checking a step counts as activity AND dismisses the
+    // re-orientation banner (the user is clearly back in flow).
+    recordActivity(parentTaskId);
+    dismissReorient();
     try {
       const result = await invoke<{
         updatedSubtask: TaskDto;
@@ -160,6 +223,10 @@
     const next = (draft[step.id] ?? '').trim();
     cancelEdit(step.id);
     if (!next || next === step.text) return;
+    // B3.4 — renaming a subtask counts as activity AND dismisses the
+    // re-orientation banner.
+    recordActivity(parentTaskId);
+    dismissReorient();
     const original = step.text;
     // Update in-memory first so the UI is snappy; roll back if the
     // persistence call fails so we never show stale-but-different text.
@@ -232,6 +299,36 @@
   {:else if error}
     <p class="text-[11px] text-text-tertiary py-1">{error}</p>
   {:else}
+    {#if reorientShown && reorientBannerText}
+      <!-- B3.4 — re-orientation banner. Shown when the parent task's
+           decomposition has been idle ≥30 min OR sat across a session
+           boundary. Self-dismisses on first interaction (handled in
+           checkStep / saveEdit) or via the explicit X. Calm style
+           matches the PR 1.4 / B3.6 / B3.1 inline banners. -->
+      <div
+        class="mb-2 px-3 py-2 rounded-lg bg-accent-subtle border border-accent/20 flex items-start gap-2"
+        role="status"
+        aria-live="polite"
+      >
+        <span class="text-[12px] text-text leading-snug flex-1 min-w-0">
+          {reorientBannerText}
+        </span>
+        <SpeakerButton
+          text={reorientBannerText}
+          label="Read this re-orientation aloud"
+          size={12}
+        />
+        <button
+          type="button"
+          class="p-0.5 text-text-tertiary hover:text-text"
+          onclick={dismissReorient}
+          aria-label="Dismiss re-orientation banner"
+          title="Dismiss"
+        >
+          <X size={12} aria-hidden="true" />
+        </button>
+      </div>
+    {/if}
     {#each subtasks as step (step.id)}
       <div class="flex items-center gap-2 group py-0.5">
         <button
diff --git a/src/lib/components/MorningTriageModal.svelte b/src/lib/components/MorningTriageModal.svelte
index e437cb8..8b1465b 100644
--- a/src/lib/components/MorningTriageModal.svelte
+++ b/src/lib/components/MorningTriageModal.svelte
@@ -18,6 +18,7 @@
   import { hasTauriRuntime } from '$lib/utils/runtime.js';
   import { settings } from '$lib/stores/page.svelte.js';
   import { toasts } from '$lib/stores/toasts.svelte.js';
+  import { inFreshStartWindow } from '$lib/utils/freshStart.js';
 
   interface TriageTask {
     id: string;
@@ -81,6 +82,11 @@
     if (open || applying) return;
     if (!settings.ritualsMorning) return;
     if (!hasTauriRuntime()) return;
+    // B3.1 — fresh-start window suppresses the morning triage modal so
+    // the calm "this week starts fresh" framing isn't undercut by an
+    // immediate triage demand. The shell banner takes the foreground;
+    // triage resumes once the 24h window closes.
+    if (inFreshStartWindow(settings.reentryFreshStartUntil)) return;
     if (currentMinutes() < parseTriggerMinutes(settings.ritualsMorningTime)) return;
 
     let lastShown: string | null = null;
diff --git a/src/lib/pages/ShutdownRitualPage.svelte b/src/lib/pages/ShutdownRitualPage.svelte
index 0a787ee..136c118 100644
--- a/src/lib/pages/ShutdownRitualPage.svelte
+++ b/src/lib/pages/ShutdownRitualPage.svelte
@@ -19,17 +19,18 @@
   import { Moon, ArrowLeft } from 'lucide-svelte';
   import { page, settings } from '$lib/stores/page.svelte.js';
   import { hasTauriRuntime } from '$lib/utils/runtime.js';
+  import { inFreshStartWindow } from '$lib/utils/freshStart.js';
 
-  // B3.14 — fresh-start gate. When B3.1 lands and stamps
+  // B3.14 — fresh-start gate. When B3.1 stamps
   // settings.reentryFreshStartUntil with a future timestamp (the user
   // has been away long enough to warrant a "yesterday is sealed"
   // window), the "Still here" reflection is suppressed so the shutdown
   // surface doesn't drag forward what the fresh-start window is
-  // explicitly inviting the user to set down. The `!!` guards against
-  // the legacy null and any malformed string.
-  const inFreshStartWindow = $derived(
-    !!settings.reentryFreshStartUntil &&
-      new Date(settings.reentryFreshStartUntil).getTime() > Date.now(),
+  // explicitly inviting the user to set down. Shared util — same
+  // gate consulted by the shell banner, morning triage, sparkline,
+  // and nudge bus.
+  const inFreshStartWindowNow = $derived(
+    inFreshStartWindow(settings.reentryFreshStartUntil),
   );
 
   interface TaskRow {
@@ -128,7 +129,7 @@
            presented with a "and 27 more" tally on the way out the door.
            Whole section is suppressed inside an active fresh-start
            window — see inFreshStartWindow above. -->
-      {#if !inFreshStartWindow}
+      {#if !inFreshStartWindowNow}
         <section class="mb-8">
           <h2 class="text-[10px] font-medium text-text-tertiary uppercase tracking-wider mb-2">Still here</h2>
           {#if openLoops.length === 0}
diff --git a/src/lib/pages/TasksPage.svelte b/src/lib/pages/TasksPage.svelte
index 2b041fb..fad6dc2 100644
--- a/src/lib/pages/TasksPage.svelte
+++ b/src/lib/pages/TasksPage.svelte
@@ -20,8 +20,18 @@
   import Card from "$lib/components/Card.svelte";
   import { formatTimestamp, todayLocalDate } from "$lib/utils/time.js";
   import { resolveEnergyLabels } from "$lib/utils/energyLabels";
+  import { inFreshStartWindow } from "$lib/utils/freshStart.js";
   import { BUCKET_COLORS, EFFORT_LABELS, EFFORT_ORDER } from "$lib/utils/constants.js";
 
+  // B3.1 — fresh-start gate. While the 24h re-entry window is open, the
+  // momentum sparkline is hidden so the header doesn't push a "look at
+  // your last 7 days" frame onto a user the app has just told "this
+  // week starts fresh". Same gate the shell banner / morning triage /
+  // nudge bus consult.
+  const inFreshStartNow = $derived(
+    inFreshStartWindow(settings.reentryFreshStartUntil),
+  );
+
   // PR 1.2: default landing bucket is Today rather than All. The cold-open
   // surface area for "what should I do now?" is now scoped to today's
   // commitments, with All still reachable as a one-click filter.
@@ -479,7 +489,7 @@
             </span>
           {/if}
 
-          {#if settings.showMomentumSparkline}
+          {#if settings.showMomentumSparkline && !inFreshStartNow}
             <CompletionSparkline data={recentCompletions} />
           {/if}
         </div>
diff --git a/src/lib/stores/nudgeBus.svelte.ts b/src/lib/stores/nudgeBus.svelte.ts
index 6e323e7..2762d36 100644
--- a/src/lib/stores/nudgeBus.svelte.ts
+++ b/src/lib/stores/nudgeBus.svelte.ts
@@ -23,6 +23,7 @@
 import { invoke } from "@tauri-apps/api/core";
 import { hasTauriRuntime } from "$lib/utils/runtime.js";
 import { settings } from "$lib/stores/page.svelte.js";
+import { inFreshStartWindow } from "$lib/utils/freshStart.js";
 
 const HOUR_MS = 60 * 60 * 1000;
 const INACTIVITY_TIMER_THRESHOLD_MS = 90_000;
@@ -94,6 +95,10 @@ function pruneRecentNudges(now: number): void {
 function canNudgeNow(now: number): boolean {
   if (!settings.nudgesEnabled) return false;
   if (settings.nudgesMuted) return false;
+  // B3.1 — fresh-start window stays quiet on every trigger. The window
+  // is the user explicitly being told "this week starts fresh"; an OS
+  // notification an hour later would directly contradict that frame.
+  if (inFreshStartWindow(settings.reentryFreshStartUntil, now)) return false;
   if (typeof document !== "undefined" && document.hasFocus()) return false;
   pruneRecentNudges(now);
   if (recentNudges.length >= 3) return false;
diff --git a/src/lib/utils/freshStart.ts b/src/lib/utils/freshStart.ts
new file mode 100644
index 0000000..d3f6633
--- /dev/null
+++ b/src/lib/utils/freshStart.ts
@@ -0,0 +1,119 @@
+/**
+ * B3.1 — fresh-start re-entry window.
+ *
+ * Single source of truth for "is the user currently inside the 24-hour
+ * fresh-start window opened by a >7-day re-entry gap?". The window is
+ * stamped onto `settings.reentryFreshStartUntil` by the app-shell launch
+ * logic in `+layout.svelte` (see `runReentryDetection`).
+ *
+ * While the window is active, four UI surfaces stay quiet:
+ *   - the morning-triage modal (won't auto-open)
+ *   - the momentum sparkline on the Tasks page (hidden)
+ *   - the nudge bus (no nudges fire)
+ *   - the ShutdownRitualPage "Still here" reflection (B3.14)
+ *
+ * The B3.1 banner in the layout shell uses the same gate to know when to
+ * render itself. Callers that depend on Svelte 5 reactivity should wrap
+ * the `inFreshStartWindow(settings.reentryFreshStartUntil)` call inside
+ * a `$derived(...)` expression so changes to the setting flow through.
+ */
+
+/**
+ * Pure check: is the supplied ISO timestamp parseable AND in the future
+ * relative to `nowMs`? Both branches that could fail (null/undefined,
+ * malformed string) collapse to `false` so callers can treat any value
+ * as safe input.
+ */
+export function inFreshStartWindow(
+  reentryFreshStartUntil: string | null | undefined,
+  nowMs: number = Date.now(),
+): boolean {
+  if (!reentryFreshStartUntil) return false;
+  const parsed = new Date(reentryFreshStartUntil).getTime();
+  if (Number.isNaN(parsed)) return false;
+  return parsed > nowMs;
+}
+
+/**
+ * Re-entry classifier used at app-shell mount.
+ *
+ * Branches:
+ *   - `firstLaunch` — `lastLaunchAt` is null (or unparseable). Caller
+ *     just stamps `lastLaunchAt = now` and saves; no fresh-start window.
+ *   - `freshStart` — gap from `lastLaunchAt` to now exceeds the
+ *     threshold (default 7 days). Caller stamps both
+ *     `reentryFreshStartUntil = now + windowMs` AND `lastLaunchAt = now`.
+ *   - `normal` — gap is within the threshold. Caller just bumps
+ *     `lastLaunchAt = now`.
+ *
+ * Returns `freshStartUntilIso` only on the freshStart branch so callers
+ * have the exact ISO string to write back without recomputing.
+ */
+export type ReentryDecision =
+  | { kind: "firstLaunch"; lastLaunchAtIso: string }
+  | { kind: "freshStart"; lastLaunchAtIso: string; freshStartUntilIso: string }
+  | { kind: "normal"; lastLaunchAtIso: string };
+
+const DAY_MS = 24 * 60 * 60 * 1000;
+const DEFAULT_REENTRY_THRESHOLD_MS = 7 * DAY_MS;
+const DEFAULT_FRESH_START_WINDOW_MS = 24 * 60 * 60 * 1000;
+
+export interface ReentryDecisionOptions {
+  /** Override "now" for testing. Defaults to `Date.now()`. */
+  nowMs?: number;
+  /** Gap above which we open a fresh-start window. Default 7 days. */
+  thresholdMs?: number;
+  /** Length of the fresh-start window. Default 24 h. */
+  windowMs?: number;
+}
+
+export function decideReentry(
+  lastLaunchAt: string | null | undefined,
+  opts: ReentryDecisionOptions = {},
+): ReentryDecision {
+  const nowMs = opts.nowMs ?? Date.now();
+  const thresholdMs = opts.thresholdMs ?? DEFAULT_REENTRY_THRESHOLD_MS;
+  const windowMs = opts.windowMs ?? DEFAULT_FRESH_START_WINDOW_MS;
+  const nowIso = new Date(nowMs).toISOString();
+
+  if (!lastLaunchAt) {
+    return { kind: "firstLaunch", lastLaunchAtIso: nowIso };
+  }
+  const last = new Date(lastLaunchAt).getTime();
+  if (Number.isNaN(last)) {
+    // Treat unparseable as first launch — safer than silently skipping
+    // the gap calculation and never stamping a fresh-start window.
+    return { kind: "firstLaunch", lastLaunchAtIso: nowIso };
+  }
+  if (nowMs - last > thresholdMs) {
+    return {
+      kind: "freshStart",
+      lastLaunchAtIso: nowIso,
+      freshStartUntilIso: new Date(nowMs + windowMs).toISOString(),
+    };
+  }
+  return { kind: "normal", lastLaunchAtIso: nowIso };
+}
+
+/**
+ * Module-scoped once-per-launch latch. The app shell calls
+ * `claimReentryLatch()` on mount; the first caller gets `true`, every
+ * subsequent caller gets `false`. Living here (not in the layout
+ * component) means HMR re-mounts of `+layout.svelte` don't double-stamp
+ * `lastLaunchAt`, and secondary windows that share the JS module graph
+ * see the same already-claimed latch.
+ *
+ * `resetReentryLatchForTests()` is provided for unit tests only — never
+ * called from production code.
+ */
+let reentryLatchClaimed = false;
+
+export function claimReentryLatch(): boolean {
+  if (reentryLatchClaimed) return false;
+  reentryLatchClaimed = true;
+  return true;
+}
+
+export function resetReentryLatchForTests(): void {
+  reentryLatchClaimed = false;
+}
diff --git a/src/lib/utils/microstepActivity.ts b/src/lib/utils/microstepActivity.ts
new file mode 100644
index 0000000..f105807
--- /dev/null
+++ b/src/lib/utils/microstepActivity.ts
@@ -0,0 +1,92 @@
+/**
+ * B3.4 — per-parent-task last-activity tracking for the MicroSteps
+ * "Where was I?" re-orientation banner.
+ *
+ * Persisted to a single localStorage key as a JSON object keyed by
+ * parent task id; the value is the ms-since-epoch timestamp of the
+ * most recent meaningful activity (subtask check, decomposition
+ * generation, subtask rename).
+ *
+ * Lives in localStorage rather than SQLite (per the spec) because the
+ * banner is a UX hint, not durable user data — the cost of losing the
+ * map on a localStorage clear is one missed banner, not a regression.
+ *
+ * Map is read lazily, mutated, and re-written on each update. The
+ * cardinality is bounded by the number of parent tasks the user has
+ * decomposed in the lifetime of the install; well within localStorage
+ * comfort.
+ */
+
+const STORAGE_KEY = "kon.microstep.lastActivity.v1";
+
+type ActivityMap = Record<string, number>;
+
+function canUseStorage(): boolean {
+  return typeof localStorage !== "undefined";
+}
+
+function readMap(): ActivityMap {
+  if (!canUseStorage()) return {};
+  const raw = localStorage.getItem(STORAGE_KEY);
+  if (!raw) return {};
+  try {
+    const parsed = JSON.parse(raw);
+    if (parsed && typeof parsed === "object") return parsed as ActivityMap;
+  } catch {
+    // Corrupt blob — drop it so we don't keep tripping the parse.
+    try { localStorage.removeItem(STORAGE_KEY); } catch {}
+  }
+  return {};
+}
+
+function writeMap(map: ActivityMap): void {
+  if (!canUseStorage()) return;
+  try {
+    localStorage.setItem(STORAGE_KEY, JSON.stringify(map));
+  } catch {
+    // Quota / disabled storage — silently drop the write. The banner
+    // gate falls back to "no last-activity recorded", which means the
+    // idle/session checks fail closed (no banner). That's fine.
+  }
+}
+
+export function getLastActivity(parentTaskId: string): number | null {
+  const map = readMap();
+  const v = map[parentTaskId];
+  return typeof v === "number" && Number.isFinite(v) ? v : null;
+}
+
+export function recordActivity(parentTaskId: string, nowMs: number = Date.now()): void {
+  if (!parentTaskId) return;
+  const map = readMap();
+  map[parentTaskId] = nowMs;
+  writeMap(map);
+}
+
+const IDLE_THRESHOLD_MS = 30 * 60 * 1000;
+
+/**
+ * The B3.4 gate: returns true when the parent's decomposition has been
+ * either (a) idle ≥30 min, OR (b) sat across a session boundary
+ * (the most recent app launch happened *after* the parent's last
+ * recorded activity — i.e. the user closed and reopened Kon since
+ * they last touched these steps).
+ *
+ * Returns false if there's no recorded activity — a fresh decomposition
+ * the user is actively working on shouldn't trigger the banner.
+ */
+export function shouldShowReorientBanner(args: {
+  parentTaskId: string;
+  lastLaunchAt: string | null | undefined;
+  nowMs?: number;
+}): boolean {
+  const last = getLastActivity(args.parentTaskId);
+  if (last === null) return false;
+  const nowMs = args.nowMs ?? Date.now();
+  if (nowMs - last > IDLE_THRESHOLD_MS) return true;
+  if (args.lastLaunchAt) {
+    const launch = new Date(args.lastLaunchAt).getTime();
+    if (!Number.isNaN(launch) && launch > last) return true;
+  }
+  return false;
+}
diff --git a/src/routes/+layout.svelte b/src/routes/+layout.svelte
index 97f9f36..77bcaf7 100644
--- a/src/routes/+layout.svelte
+++ b/src/routes/+layout.svelte
@@ -30,6 +30,11 @@
     startImplementationIntentions,
     stopImplementationIntentions,
   } from "$lib/stores/implementationIntentions.svelte.ts";
+  import {
+    claimReentryLatch,
+    decideReentry,
+    inFreshStartWindow,
+  } from "$lib/utils/freshStart.js";
 
   import { page as sveltePage } from "$app/stores";
 
@@ -243,6 +248,72 @@
   let onWindowError = null;
   let onUnhandledRejection = null;
 
+  // ---------------------------------------------------------------
+  // B3.1 — re-entry / fresh-start detection.
+  //
+  // Runs exactly once per app launch (the module-scoped flag below
+  // survives Svelte's HMR re-mounts and protects the secondary-window
+  // case where +layout.svelte may be parsed twice). A >7-day gap from
+  // the last launch opens a 24h fresh-start window; the banner below
+  // renders while that window is in the future, and the four
+  // suppression sites (morning-triage modal, momentum sparkline,
+  // nudge bus, shutdown ritual) all read the same gate via
+  // inFreshStartWindow() in $lib/utils/freshStart.
+  let archivingOldInbox = $state(false);
+  // Per-session dismiss for the welcome-back banner. Module-scoped so
+  // dismissing on one navigation doesn't re-show on the next; reset on
+  // app restart by virtue of being a fresh module load.
+  let bannerDismissedThisSession = $state(false);
+
+  // Reactive banner gate. The fresh-start util takes the raw setting so
+  // any change to settings.reentryFreshStartUntil flows through.
+  const showFreshStartBanner = $derived(
+    inFreshStartWindow(settings.reentryFreshStartUntil) &&
+      !bannerDismissedThisSession,
+  );
+
+  function runReentryDetection() {
+    // claimReentryLatch() returns true exactly once per JS module load
+    // — secondary windows that share the module graph and HMR remounts
+    // both see "already claimed" and skip the stamp.
+    if (!claimReentryLatch()) return;
+    const decision = decideReentry(settings.lastLaunchAt);
+    settings.lastLaunchAt = decision.lastLaunchAtIso;
+    if (decision.kind === "freshStart") {
+      settings.reentryFreshStartUntil = decision.freshStartUntilIso;
+    }
+    saveSettings();
+  }
+
+  async function archiveOldInbox() {
+    if (archivingOldInbox) return;
+    if (!hasTauriRuntime()) {
+      bannerDismissedThisSession = true;
+      return;
+    }
+    archivingOldInbox = true;
+    try {
+      // Inbox-only by design — see archive_old_inbox_cmd in tasks.rs.
+      // We swallow the rows_affected count: the toast copy is
+      // system-attributable per the B3.1 memo §A and must not say
+      // "we archived N items" (RSD-sensitive copy rule).
+      await invoke("archive_old_inbox_cmd", { days: 7 });
+      toasts.success(
+        "The inbox overflowed. Anything important will come back.",
+      );
+    } catch (err) {
+      const msg = err instanceof Error ? err.message : String(err);
+      toasts.error("Couldn't archive old Inbox", msg);
+    } finally {
+      archivingOldInbox = false;
+      bannerDismissedThisSession = true;
+    }
+  }
+
+  function dismissFreshStartBanner() {
+    bannerDismissedThisSession = true;
+  }
+
   function installGlobalErrorCapture() {
     if (!hasTauriRuntime()) return;
 
@@ -272,6 +343,11 @@
   }
 
   onMount(async () => {
+    // B3.1 — re-entry / fresh-start detection. Runs first so the
+    // suppression sites (morning triage, momentum sparkline, nudge
+    // bus) see the right gate state when they initialise below.
+    runReentryDetection();
+
     // Auto-collapse if window is already narrow on first load
     handleResize();
     window.addEventListener("resize", handleResize);
@@ -425,8 +501,43 @@
       {#if page.current !== "first-run"}
         <Sidebar />
       {/if}
-      <div class="flex-1 overflow-hidden bg-bg">
-        {@render children()}
+      <div class="flex-1 overflow-hidden bg-bg flex flex-col min-w-0">
+        {#if showFreshStartBanner && page.current !== "first-run"}
+          <!-- B3.1 fresh-start banner. Shown when the user has been
+               away >7 days; offers a one-tap Inbox archive (Inbox-only
+               via archive_old_inbox_cmd) and a per-session dismiss.
+               Calm style matches the PR 1.4 / B3.6 inline banners. -->
+          <div class="px-7 pt-3 pb-1 animate-fade-in">
+            <div
+              class="px-4 py-2 rounded-lg bg-accent-subtle border border-accent/20 text-[12px] flex items-center gap-3"
+              role="status"
+              aria-live="polite"
+            >
+              <span class="text-text">Welcome back. This week starts fresh.</span>
+              <div class="flex-1"></div>
+              <button
+                type="button"
+                class="px-3 py-1 rounded-md text-[11px] font-medium bg-accent text-white hover:bg-accent-hover disabled:opacity-50"
+                onclick={archiveOldInbox}
+                disabled={archivingOldInbox}
+              >
+                {archivingOldInbox ? "Archiving…" : "Archive old Inbox"}
+              </button>
+              <button
+                type="button"
+                class="px-2 py-1 text-text-tertiary hover:text-text"
+                onclick={dismissFreshStartBanner}
+                aria-label="Dismiss this banner for this session"
+                title="Dismiss"
+              >
+                ×
+              </button>
+            </div>
+          </div>
+        {/if}
+        <div class="flex-1 min-h-0 overflow-hidden">
+          {@render children()}
+        </div>
       </div>
       {#if page.taskSidebarOpen && page.current !== "first-run"}
         <div class="w-[280px] min-w-[280px] shadow-xl">