docs(status): note the window the age cannot cover, and read better inside it

README.md

@@ -53,6 +53,7 @@ republishes what it last heard rather than going quiet, and the age of that read
 shown alongside it.
 
 ```
+CONNECTED   fw 2.1.2 · 100% (4.17V) · media ok · Q223P4C31420105 · seen just now
 CONNECTED   fw 2.1.2 · 100% (4.17V) · media ok · Q223P4C31420105 · seen 6h ago
 ```
 
@@ -61,6 +62,15 @@ rather than overruling it — a printer that had tape six hours ago is far likel
 still have tape than to have anything else — so the status mapping is unchanged. An
 agent too old to publish the field renders exactly as it did before.
 
+One case the age cannot cover: the agent's MQTT will is fixed when its connection opens
+and the broker holds it, so a printer fault learned *during* that session cannot reach
+it. If the agent is then killed, the broker publishes the older, healthier reading over
+the newer one, and this page renders it — correctly marked `DISCONNECTED`, but with a
+stale-healthy detail line. It is self-correcting rather than sticky: the agent restarts
+(`Restart=always`, `RestartSec=5`), seeds from its spool, which does have the fault, and
+republishes. Nothing here can detect the window, since retained MQTT v3.1.1 messages
+carry no publish timestamp.
+
 ## Print outcomes
 
 `AWAIT_RESULT_S` makes the driver wait for the job's `JobResult` after dispatching, so

inventree_label_dispatch/status.py

@@ -29,9 +29,14 @@
 _GOOD_JOB_STATES = frozenset({"completed"})
 
 
-def _ago(seen, now: datetime) -> str:
+def _ago(seen: object, now: datetime) -> str:
     """How long ago the device fields were true, as a short suffix. ``""`` if unknown.
 
+    ``seen`` is typed as ``object`` rather than ``str | None`` on purpose: it comes
+    straight out of ``json.loads`` on a payload this process did not produce, so it can
+    be any JSON type at all, and pretending otherwise would just move the lie into the
+    annotation.
+
     Empty rather than a guess in three cases, all of which mean the same thing: nobody
     said. An agent older than the field simply omits it, and the page should look
     exactly as it did before rather than sprouting a fake age.
@@ -52,6 +57,11 @@ def _ago(seen, now: datetime) -> str:
     # Clamped at zero: the agent's clock and this one are not the same clock, and a
     # small skew must read as "just now", never as a negative age.
     delta = max(0, int((now - stamp).total_seconds()))
+    # A reading taken while the operator was watching the print happen. "seen 0s ago"
+    # is technically right and reads like a machine; this is the common case, since the
+    # page is usually looked at right after printing something.
+    if delta < 10:
+        return "seen just now"
     if delta < 60:
         return f"seen {delta}s ago"
     if delta < 3600:

tests/test_status.py

@@ -140,7 +140,8 @@ def _seen(delta: timedelta) -> dict:
 @pytest.mark.parametrize(
     ("delta", "expected"),
     [
-        (timedelta(seconds=0), "seen 0s ago"),
+        (timedelta(seconds=0), "seen just now"),
+        (timedelta(seconds=9), "seen just now"),
         (timedelta(seconds=42), "seen 42s ago"),
         (timedelta(minutes=4), "seen 4m ago"),
         (timedelta(hours=6), "seen 6h ago"),
@@ -188,7 +189,8 @@ def test_a_naive_timestamp_is_read_as_utc():
 def test_a_clock_ahead_of_ours_reads_as_just_now_not_a_negative_age():
     """The agent's clock and InvenTree's are not the same clock."""
     _member, text = classify_status(_seen(timedelta(minutes=-5)), now=NOW)
-    assert "seen 0s ago" in text
+    assert "seen just now" in text
+    assert "-" not in text.split("seen")[-1]
 
 
 # -- job outcomes ----------------------------------------------------------- #