diff --git a/server/state.ts b/server/state.ts
index 8eabff3..875b248 100644
--- a/server/state.ts
+++ b/server/state.ts
@@ -454,6 +454,10 @@ export interface StatusState {
   reaction: string;
   muted: boolean;
   achievement: string;
+  /** Epoch ms the achievement was awarded; 0 when none. The statusline expires
+   *  the trophy banner on this, otherwise it latches into the shared
+   *  status.json and pins every session's bubble to the last unlock. */
+  achievementAt: number;
   frames: string[];
   compactFrames: string[];
   minimalFrames: string[];
@@ -543,6 +547,7 @@ export function writeStatusState(
     reaction: "",
     muted: muted ?? false,
     achievement: achievement ?? "",
+    achievementAt: achievement ? Date.now() : 0,
     frames,
     compactFrames,
     minimalFrames,
diff --git a/statusline/buddy-status.sh b/statusline/buddy-status.sh
index 62404a8..b8d1c15 100755
--- a/statusline/buddy-status.sh
+++ b/statusline/buddy-status.sh
@@ -58,6 +58,9 @@ STARS=$(jq -r '.stars // ""' "$STATE" 2>/dev/null)
 SHINY=$(jq -r '.shiny // false' "$STATE" 2>/dev/null)
 REACTION_FILE="$BUDDY_STATE_DIR/reaction.$SID.json"
 ACHIEVEMENT=$(jq -r '.achievement // ""' "$STATE" 2>/dev/null)
+# "absent" distinguishes a legacy status.json (no field at all) from an explicit
+# 0, which means "no achievement pending" and must not render.
+ACHIEVEMENT_AT=$(jq -r 'if has("achievementAt") then (.achievementAt // 0) else "absent" end' "$STATE" 2>/dev/null)
 LEVEL=$(jq -r '.level // 1' "$STATE" 2>/dev/null)
 MOOD=$(jq -r '.mood // "focused"' "$STATE" 2>/dev/null)
 
@@ -229,10 +232,10 @@ DETECTED_COLS="$COLS"
 DETECTED_ROWS="$ROWS"
 
 # ─── Reaction bubble (with TTL check) ────────────────────────────────────────
+# The achievement banner is resolved further down, once REACTION_TTL is known —
+# it expires on the same clock as a reaction. Without that it latches into the
+# shared status.json and pins every session's bubble to the last trophy.
 BUBBLE=""
-if [ -n "$ACHIEVEMENT" ] && [ "$ACHIEVEMENT" != "null" ] && [ "$ACHIEVEMENT" != "" ]; then
-    BUBBLE=$'\xf0\x9f\x8f\x86'" $ACHIEVEMENT"
-fi
 REACTION_TTL=900
 INNER_W=44
 MARGIN=8
@@ -307,6 +310,31 @@ _sweep_expired_reactions() {
 }
 
 _sweep_expired_reactions
+
+# Achievement banner: shown only while fresh. ACHIEVEMENT_AT is epoch ms, written
+# alongside the name by writeStatusState. A legacy status.json without the field
+# (pre-upgrade, or a snapshot fixture) is treated as fresh — the next write from
+# the server backfills it.
+#
+# Validity and age are separate gates on purpose. A zeroed or malformed
+# achievementAt means "nothing pending" and must never render, including under
+# reactionTTL=0 — that opt-out disables *expiry*, not the field's meaning.
+if [ -n "$ACHIEVEMENT" ] && [ "$ACHIEVEMENT" != "null" ]; then
+    ACH_FRESH=1
+    if [ "$ACHIEVEMENT_AT" != "absent" ]; then
+        case "$ACHIEVEMENT_AT" in
+            ''|0|*[!0-9]*) ACH_FRESH=0 ;;
+            *)
+                if [ "$REACTION_TTL" -gt 0 ] 2>/dev/null; then
+                    ACH_AGE=$(( ($(date +%s) * 1000 - ACHIEVEMENT_AT) / 1000 ))
+                    [ "$ACH_AGE" -ge "$REACTION_TTL" ] && ACH_FRESH=0
+                fi
+                ;;
+        esac
+    fi
+    [ "$ACH_FRESH" -eq 1 ] && BUBBLE=$'\xf0\x9f\x8f\x86'" $ACHIEVEMENT"
+fi
+
 REACTION=$(jq -r '.reaction // ""' "$REACTION_FILE" 2>/dev/null)
 if [ -n "$REACTION" ] && [ "$REACTION" != "null" ] && [ "$REACTION" != "" ]; then
     FRESH=0
diff --git a/statusline/buddy-status.test.ts b/statusline/buddy-status.test.ts
index 5ed3576..3c840d9 100644
--- a/statusline/buddy-status.test.ts
+++ b/statusline/buddy-status.test.ts
@@ -584,3 +584,86 @@ describe("statusline density", () => {
     expect(narrow.stdout.toString()).not.toContain("long-reaction-text");
   });
 });
+
+describe("achievement banner expiry", () => {
+  function writeStatus(stateDir: string, extra: Record<string, unknown>) {
+    writeFileSync(join(stateDir, "status.json"), JSON.stringify({
+      name: "Nimbus",
+      rarity: "common",
+      stars: "★",
+      shiny: false,
+      reaction: "",
+      level: 1,
+      mood: "focused",
+      frames: ["  art"],
+      frameSequence: [0],
+      ...extra,
+    }));
+  }
+
+  test("shows a freshly awarded achievement", () => {
+    const { configDir, stateDir } = createStatuslineFixture({ reactionTTL: 900 });
+    writeStatus(stateDir, { achievement: "🕊️ Diplomat", achievementAt: Date.now() });
+
+    const result = runStatusline(configDir);
+
+    expect(result.status).toBe(0);
+    expect(result.stdout.toString()).toContain("Diplomat");
+  });
+
+  test("drops an achievement older than the reaction TTL", () => {
+    const { configDir, stateDir } = createStatuslineFixture({ reactionTTL: 900 });
+    writeStatus(stateDir, {
+      achievement: "🕊️ Diplomat",
+      achievementAt: Date.now() - 901_000,
+    });
+
+    const result = runStatusline(configDir);
+
+    expect(result.status).toBe(0);
+    expect(result.stdout.toString()).not.toContain("Diplomat");
+  });
+
+  test("does not render a banner when achievementAt is zeroed", () => {
+    const { configDir, stateDir } = createStatuslineFixture({ reactionTTL: 900 });
+    writeStatus(stateDir, { achievement: "🕊️ Diplomat", achievementAt: 0 });
+
+    const result = runStatusline(configDir);
+
+    expect(result.status).toBe(0);
+    expect(result.stdout.toString()).not.toContain("Diplomat");
+  });
+
+  test("never renders a zeroed achievementAt even when reactionTTL disables expiry", () => {
+    const { configDir, stateDir } = createStatuslineFixture({ reactionTTL: 0 });
+    writeStatus(stateDir, { achievement: "\u{1F54A}\uFE0F Diplomat", achievementAt: 0 });
+
+    const result = runStatusline(configDir);
+
+    expect(result.status).toBe(0);
+    expect(result.stdout.toString()).not.toContain("Diplomat");
+  });
+
+  test("reactionTTL=0 keeps a validly stamped achievement from expiring", () => {
+    const { configDir, stateDir } = createStatuslineFixture({ reactionTTL: 0 });
+    writeStatus(stateDir, {
+      achievement: "\u{1F54A}\uFE0F Diplomat",
+      achievementAt: Date.now() - 86_400_000,
+    });
+
+    const result = runStatusline(configDir);
+
+    expect(result.status).toBe(0);
+    expect(result.stdout.toString()).toContain("Diplomat");
+  });
+
+  test("treats a legacy status.json without achievementAt as fresh", () => {
+    const { configDir, stateDir } = createStatuslineFixture({ reactionTTL: 900 });
+    writeStatus(stateDir, { achievement: "🕊️ Diplomat" });
+
+    const result = runStatusline(configDir);
+
+    expect(result.status).toBe(0);
+    expect(result.stdout.toString()).toContain("Diplomat");
+  });
+});