fix(observatory): clamp held_seconds and treat epoch-0 claim as present

Fold gitar edge-case: use 'claimed_at is not None' so an epoch-0 timestamp is
not read as missing, and max(0, ...) so clock skew (a claim stamped slightly in
the future) cannot report a negative age. Adds a clock-skew test.

Author: jaylfc

tests/test_routes_observatory.py

@@ -211,3 +211,24 @@ async def test_fleet_idle_agent_has_uniform_badge_shape(app, client):
     assert len(idle) == 1
     assert idle[0]["held_seconds"] is None
     assert idle[0]["stale"] is False
+
+
+@pytest.mark.asyncio
+async def test_fleet_clamps_held_seconds_under_clock_skew(app, client):
+    import time
+
+    pstore = app.state.project_store
+    tstore = app.state.project_task_store
+    proj = await pstore.create_project(name="ObsSkew", slug="obs-skew", created_by="admin", user_id="admin")
+    task = await tstore.create_task(proj["id"], title="Future card", created_by="admin")
+    await tstore.claim_task(task["id"], "@lane-skew")
+    # Claim stamped slightly in the future (clock skew) must not yield a negative age.
+    await tstore._db.execute(
+        "UPDATE project_tasks SET claimed_at = ? WHERE id = ?", (time.time() + 600, task["id"]))
+    await tstore._db.commit()
+
+    agents = (await client.get("/api/observatory/fleet")).json()["agents"]
+    mine = [a for a in agents if a["handle"] == "@lane-skew"]
+    assert len(mine) == 1
+    assert mine[0]["held_seconds"] == 0
+    assert mine[0]["stale"] is False

tinyagentos/routes/observatory.py

@@ -210,9 +210,13 @@ async def get_fleet(request: Request, user: CurrentUser = Depends(current_user))
                 continue
             working.add(handle)
             # Claim age drives the stale badge. claimed_at is a Unix epoch set on
-            # claim; guard a missing/None value (it must not break the view).
+            # claim. Use `is not None` so an epoch-0 timestamp is not mistaken for
+            # missing, and clamp to >= 0 so clock skew (claimed_at slightly in the
+            # future) cannot report a negative age.
             claimed_at = t.get("claimed_at")
-            held_seconds = int(now - claimed_at) if claimed_at else None
+            held_seconds = (
+                max(0, int(now - claimed_at)) if claimed_at is not None else None
+            )
             agents.append({
                 "handle": handle,
                 "state": "working",