diff --git a/backend/app/api/routes/scan.py b/backend/app/api/routes/scan.py
index 5377cb6..0ef6398 100644
--- a/backend/app/api/routes/scan.py
+++ b/backend/app/api/routes/scan.py
@@ -1,6 +1,7 @@
 import ipaddress
 import logging
 import uuid
+from datetime import datetime
 from typing import Any
 
 from fastapi import APIRouter, BackgroundTasks, Depends, HTTPException
@@ -193,51 +194,80 @@ async def stop_scan(
     return {"stopping": True}
 
 
-async def _canvas_counts(
-    db: AsyncSession, devices: list[PendingDevice]
-) -> dict[str, int]:
-    """Map each device id → number of distinct canvases (designs) it appears on.
+def _agg(values: list[datetime], *, newest: bool) -> datetime | None:
+    """Pick the newest (max) or oldest (min) of a list of timestamps, or None."""
+    present = [v for v in values if v is not None]
+    if not present:
+        return None
+    return max(present) if newest else min(present)
 
-    Correlates a scanned device to existing nodes by ``ieee_address`` (exact) or
-    ``ip`` (exact). Runs a single node query and groups in Python — node counts are
-    small for a homelab, so this avoids an N+1 per device.
+
+async def _canvas_correlation(
+    db: AsyncSession, devices: list[PendingDevice]
+) -> dict[str, dict[str, Any]]:
+    """Correlate each device to existing canvas nodes by ``ieee_address`` or ``ip``.
+
+    Returns, per device id: the number of distinct canvases (designs) it appears
+    on, plus aggregated timestamps from every matching node — created_at (oldest),
+    last_scan / updated_at / last_seen (newest). One node query, grouped in Python
+    (node counts are small for a homelab), so no N+1 per device.
     """
     if not devices:
         return {}
     rows = (
         await db.execute(
-            select(Node.ip, Node.ieee_address, Node.design_id).where(
-                Node.design_id.isnot(None)
-            )
+            select(
+                Node.ip,
+                Node.ieee_address,
+                Node.design_id,
+                Node.created_at,
+                Node.last_scan,
+                Node.updated_at,
+                Node.last_seen,
+            ).where(Node.design_id.isnot(None))
         )
     ).all()
-    # ip → set(design_id), ieee → set(design_id)
-    by_ip: dict[str, set[str]] = {}
-    by_ieee: dict[str, set[str]] = {}
-    for ip, ieee, design_id in rows:
-        if ip:
-            by_ip.setdefault(ip, set()).add(design_id)
-        if ieee:
-            by_ieee.setdefault(ieee, set()).add(design_id)
+    # Index matching nodes by ip and by ieee so a device can look up both.
+    by_ip: dict[str, list[Any]] = {}
+    by_ieee: dict[str, list[Any]] = {}
+    for row in rows:
+        if row.ip:
+            by_ip.setdefault(row.ip, []).append(row)
+        if row.ieee_address:
+            by_ieee.setdefault(row.ieee_address, []).append(row)
 
-    counts: dict[str, int] = {}
+    info: dict[str, dict[str, Any]] = {}
     for d in devices:
-        designs: set[str] = set()
+        matched = []
         if d.ieee_address:
-            designs |= by_ieee.get(d.ieee_address, set())
+            matched += by_ieee.get(d.ieee_address, [])
         if d.ip:
-            designs |= by_ip.get(d.ip, set())
-        counts[d.id] = len(designs)
-    return counts
+            matched += by_ip.get(d.ip, [])
+        # De-duplicate nodes matched by both ip and ieee.
+        matched = list({id(m): m for m in matched}.values())
+        designs = {m.design_id for m in matched}
+        info[d.id] = {
+            "canvas_count": len(designs),
+            "node_created_at": _agg([m.created_at for m in matched], newest=False),
+            "node_last_scan": _agg([m.last_scan for m in matched], newest=True),
+            "node_last_modified": _agg([m.updated_at for m in matched], newest=True),
+            "node_last_seen": _agg([m.last_seen for m in matched], newest=True),
+        }
+    return info
 
 
 async def _with_canvas_counts(
     db: AsyncSession, devices: list[PendingDevice]
 ) -> list[PendingDevice]:
-    """Attach a transient ``canvas_count`` to each device for the response schema."""
-    counts = await _canvas_counts(db, devices)
+    """Attach transient canvas count + linked-node timestamps for the response."""
+    info = await _canvas_correlation(db, devices)
     for d in devices:
-        d.canvas_count = counts.get(d.id, 0)
+        meta = info.get(d.id, {})
+        d.canvas_count = meta.get("canvas_count", 0)
+        d.node_created_at = meta.get("node_created_at")
+        d.node_last_scan = meta.get("node_last_scan")
+        d.node_last_modified = meta.get("node_last_modified")
+        d.node_last_seen = meta.get("node_last_seen")
     return devices
 
 
@@ -278,15 +308,38 @@ async def bulk_approve_devices(
         first_design = (await db.execute(select(Design).order_by(Design.created_at).limit(1))).scalar()
         default_design_id = first_design.id if first_design else None
 
+    # Accept every selected device that isn't user-hidden. We intentionally do NOT
+    # filter on status == "pending": a device's status is global, but canvas
+    # membership is per-design. A device approved onto another canvas (or whose
+    # node was later deleted) must still be placeable on THIS design. Duplicates
+    # are guarded per-design below, not by the global status flag.
     result = await db.execute(
         select(PendingDevice).where(
             PendingDevice.id.in_(payload.device_ids),
-            PendingDevice.status == "pending",
+            PendingDevice.status != "hidden",
         )
     )
     devices = result.scalars().all()
+
+    # What already sits on the target canvas, so we skip devices already placed
+    # here (by ip or ieee_address) instead of creating duplicate nodes.
+    existing = (
+        await db.execute(
+            select(Node.ip, Node.ieee_address).where(Node.design_id == default_design_id)
+        )
+    ).all()
+    placed_ips = {ip for ip, _ in existing if ip}
+    placed_ieee = {ieee for _, ieee in existing if ieee}
+
     created_nodes: list[Node] = []
+    approved_devices: list[PendingDevice] = []
     for device in devices:
+        already_here = (
+            (device.ip is not None and device.ip in placed_ips)
+            or (device.ieee_address is not None and device.ieee_address in placed_ieee)
+        )
+        if already_here:
+            continue
         device.status = "approved"
         node_type = device.suggested_type or "generic"
         is_wireless = _is_wireless(node_type)
@@ -309,12 +362,20 @@ async def bulk_approve_devices(
         )
         db.add(node)
         created_nodes.append(node)
+        approved_devices.append(device)
+        # Track within this batch so a duplicate selection (same ip/ieee) is not
+        # placed twice on the same canvas.
+        if device.ip:
+            placed_ips.add(device.ip)
+        if device.ieee_address:
+            placed_ieee.add(device.ieee_address)
     await db.flush()  # populates node.id from Python-side default before reading
+    # node_ids and approved_device_ids stay index-aligned for the client's mapping.
     node_ids = [n.id for n in created_nodes]
-    approved_device_ids = [d.id for d in devices]
+    approved_device_ids = [d.id for d in approved_devices]
 
     all_edges: list[dict[str, str]] = []
-    for device in devices:
+    for device in approved_devices:
         all_edges.extend(await _resolve_pending_links_for_ieee(db, device.ieee_address))
 
     await db.commit()
diff --git a/backend/app/db/database.py b/backend/app/db/database.py
index a95258a..041aed9 100644
--- a/backend/app/db/database.py
+++ b/backend/app/db/database.py
@@ -293,6 +293,9 @@ async def init_db() -> None:
                     "UPDATE nodes SET properties = ? WHERE id = ?",
                     (_json.dumps(props), node_id),
                 )
+        # Inventory timestamp: last time a scan observed this node (idempotent)
+        with suppress(OperationalError):
+            await conn.exec_driver_sql("ALTER TABLE nodes ADD COLUMN last_scan DATETIME")
         # Migrate animated column from boolean (0/1) to string ('none'/'snake')
         with suppress(OperationalError):
             await conn.exec_driver_sql("UPDATE edges SET animated = 'snake' WHERE animated = '1' OR animated = 1")
diff --git a/backend/app/db/models.py b/backend/app/db/models.py
index 1e49386..f749cc7 100644
--- a/backend/app/db/models.py
+++ b/backend/app/db/models.py
@@ -61,6 +61,7 @@ class Node(Base):
     bottom_handles: Mapped[int] = mapped_column(Integer, default=1)
     ieee_address: Mapped[str | None] = mapped_column(String, index=True, nullable=True)
     last_seen: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+    last_scan: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
     response_time_ms: Mapped[int | None] = mapped_column(Integer)
     created_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=_now)
     updated_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), default=_now, onupdate=_now)
@@ -99,6 +100,9 @@ class CanvasState(Base):
 
 class PendingDevice(Base):
     __tablename__ = "pending_devices"
+    # Permit the plain (non-Mapped[]) annotations on the transient request-only
+    # attributes below; without this SQLAlchemy 2.0 tries to map them as columns.
+    __allow_unmapped__ = True
 
     id: Mapped[str] = mapped_column(String, primary_key=True, default=_uuid)
     ip: Mapped[str | None] = mapped_column(String, nullable=True)
@@ -120,6 +124,12 @@ class PendingDevice(Base):
     # Transient (not persisted): populated per-request by the scan routes to report
     # how many canvases this device already appears on. Not a mapped column.
     canvas_count: int = 0
+    # Transient (not persisted): timestamps from the linked canvas node(s),
+    # correlated by ip / ieee_address. None when the device is not on any canvas.
+    node_created_at: datetime | None = None
+    node_last_scan: datetime | None = None
+    node_last_modified: datetime | None = None
+    node_last_seen: datetime | None = None
 
 
 class PendingDeviceLink(Base):
diff --git a/backend/app/schemas/nodes.py b/backend/app/schemas/nodes.py
index 5c220ed..4fb3597 100644
--- a/backend/app/schemas/nodes.py
+++ b/backend/app/schemas/nodes.py
@@ -73,6 +73,7 @@ class NodeResponse(NodeBase):
     design_id: str | None = None
     ieee_address: str | None = None
     last_seen: datetime | None = None
+    last_scan: datetime | None = None
     response_time_ms: int | None = None
     created_at: datetime
     updated_at: datetime
diff --git a/backend/app/schemas/scan.py b/backend/app/schemas/scan.py
index b0f5b78..3b7cef7 100644
--- a/backend/app/schemas/scan.py
+++ b/backend/app/schemas/scan.py
@@ -24,6 +24,13 @@ class PendingDeviceResponse(BaseModel):
     # Number of distinct canvases (designs) this device already appears on,
     # correlated by ip / ieee_address against existing nodes. Computed per-request.
     canvas_count: int = 0
+    # Timestamps from the linked canvas node(s), correlated by ip / ieee_address.
+    # Null when the device is not on any canvas yet. Aggregated across matches:
+    # created_at = oldest; last_scan / last_modified / last_seen = newest.
+    node_created_at: datetime | None = None
+    node_last_scan: datetime | None = None
+    node_last_modified: datetime | None = None
+    node_last_seen: datetime | None = None
 
     model_config = {"from_attributes": True}
 
diff --git a/backend/app/services/scanner.py b/backend/app/services/scanner.py
index c19d1a5..07401e8 100644
--- a/backend/app/services/scanner.py
+++ b/backend/app/services/scanner.py
@@ -11,10 +11,10 @@ from dataclasses import dataclass, field
 from datetime import datetime, timezone
 from typing import Any
 
-from sqlalchemy import select
+from sqlalchemy import or_, select
 from sqlalchemy.ext.asyncio import AsyncSession
 
-from app.db.models import PendingDevice, ScanRun
+from app.db.models import Node, PendingDevice, ScanRun
 from app.services.fingerprint import fingerprint_ports, suggest_node_type
 from app.services.http_probe import probe_open_ports
 
@@ -542,6 +542,20 @@ async def run_scan(
                 ))
                 devices_found += 1
 
+            # Stamp last_scan on any canvas node that matches this device by IP
+            # (or MAC, when known) so the inventory shows when the scanner last
+            # observed it. Matches across designs.
+            host_mac = host.get("mac")
+            node_match = [Node.ip == ip]
+            if host_mac:
+                node_match.append(Node.mac == host_mac)
+            matching_nodes = (await db.execute(
+                select(Node).where(or_(*node_match))
+            )).scalars().all()
+            scanned_at = datetime.now(timezone.utc)
+            for node in matching_nodes:
+                node.last_scan = scanned_at
+
             await db.commit()
             await broadcast_scan_update(run_id=run_id, devices_found=devices_found)
 
diff --git a/backend/tests/test_canvas.py b/backend/tests/test_canvas.py
index 19202b6..d26e9c6 100644
--- a/backend/tests/test_canvas.py
+++ b/backend/tests/test_canvas.py
@@ -51,6 +51,18 @@ async def test_save_canvas_creates_nodes_and_edges(client: AsyncClient, headers:
     assert canvas["viewport"] == {"x": 1, "y": 2, "zoom": 1.5}
 
 
+async def test_load_canvas_exposes_inventory_timestamps(client: AsyncClient, headers: dict):
+    n1 = node_payload(label="Router", type="router")
+    await client.post("/api/v1/canvas/save", json={"nodes": [n1], "edges": [], "viewport": {}}, headers=headers)
+
+    node = (await client.get("/api/v1/canvas", headers=headers)).json()["nodes"][0]
+    # created_at / updated_at always set; last_seen / last_scan null until observed.
+    assert node["created_at"] is not None
+    assert node["updated_at"] is not None
+    assert "last_seen" in node
+    assert node["last_scan"] is None
+
+
 async def test_save_canvas_updates_existing_node(client: AsyncClient, headers: dict):
     n1 = node_payload(label="Old Label")
     await client.post("/api/v1/canvas/save", json={"nodes": [n1], "edges": [], "viewport": {}}, headers=headers)
diff --git a/backend/tests/test_migrations.py b/backend/tests/test_migrations.py
index fe225f9..d4f2d33 100644
--- a/backend/tests/test_migrations.py
+++ b/backend/tests/test_migrations.py
@@ -105,6 +105,28 @@ async def test_legacy_canvas_migrates_into_default_design(legacy_engine):
         await engine.dispose()
 
 
+async def test_legacy_nodes_gain_last_scan_column(legacy_engine):
+    """A legacy nodes table (no last_scan) gains the column after init_db."""
+    db_path, engine = legacy_engine
+    await _build_legacy_schema(engine)
+
+    await database.init_db()
+
+    check = create_async_engine(f"sqlite+aiosqlite:///{db_path}")
+    try:
+        async with check.begin() as conn:
+            cols = (await conn.exec_driver_sql("PRAGMA table_info(nodes)")).fetchall()
+            assert "last_scan" in {c[1] for c in cols}
+            # Existing rows backfill to NULL (never scanned yet).
+            last_scan = (await conn.exec_driver_sql(
+                "SELECT last_scan FROM nodes WHERE id='n1'"
+            )).fetchone()
+            assert last_scan[0] is None
+    finally:
+        await check.dispose()
+        await engine.dispose()
+
+
 async def test_migration_is_idempotent(legacy_engine):
     """Running init_db twice must not duplicate the design or drop any data."""
     db_path, engine = legacy_engine
diff --git a/backend/tests/test_scan.py b/backend/tests/test_scan.py
index b9213c8..3b05eb0 100644
--- a/backend/tests/test_scan.py
+++ b/backend/tests/test_scan.py
@@ -1,5 +1,6 @@
 """Tests for scan routes: trigger, pending devices, approve/hide/ignore, stop."""
 import uuid
+from datetime import datetime, timezone
 from unittest.mock import AsyncMock, patch
 
 import pytest
@@ -229,6 +230,56 @@ async def test_canvas_count_ignores_nodes_without_design(client, headers, db_ses
     assert res.json()[0]["canvas_count"] == 0
 
 
+# --- Linked-node timestamps on the inventory response ---
+
+@pytest.mark.asyncio
+async def test_pending_device_without_node_has_null_node_timestamps(client, headers, pending_device):
+    # No matching canvas node → node_* timestamps are all null; the device still
+    # carries its own discovered_at for the "Discovered" fallback on the tile.
+    data = (await client.get("/api/v1/scan/pending", headers=headers)).json()[0]
+    assert data["discovered_at"] is not None
+    assert data["node_created_at"] is None
+    assert data["node_last_scan"] is None
+    assert data["node_last_modified"] is None
+    assert data["node_last_seen"] is None
+
+
+@pytest.mark.asyncio
+async def test_pending_device_exposes_linked_node_timestamps(client, headers, db_session, pending_device):
+    d1 = await _add_design(db_session, "Home")
+    node = _node(d1, ip="192.168.1.100")
+    node.last_scan = datetime(2026, 6, 1, 8, 30, tzinfo=timezone.utc)
+    node.last_seen = datetime(2026, 6, 25, 9, 15, tzinfo=timezone.utc)
+    db_session.add(node)
+    await db_session.commit()
+
+    data = (await client.get("/api/v1/scan/pending", headers=headers)).json()[0]
+    assert data["node_created_at"] is not None      # defaulted on insert
+    assert data["node_last_modified"] is not None    # updated_at defaulted on insert
+    assert data["node_last_scan"].startswith("2026-06-01")
+    assert data["node_last_seen"].startswith("2026-06-25")
+
+
+@pytest.mark.asyncio
+async def test_node_timestamps_aggregate_across_matches(client, headers, db_session, pending_device):
+    # Two canvas nodes share the device IP: created_at takes the OLDEST,
+    # last_scan takes the NEWEST.
+    d1 = await _add_design(db_session, "Home")
+    d2 = await _add_design(db_session, "Lab")
+    older = _node(d1, ip="192.168.1.100")
+    older.created_at = datetime(2026, 1, 1, 0, 0, tzinfo=timezone.utc)
+    older.last_scan = datetime(2026, 3, 1, 0, 0, tzinfo=timezone.utc)
+    newer = _node(d2, ip="192.168.1.100")
+    newer.created_at = datetime(2026, 5, 1, 0, 0, tzinfo=timezone.utc)
+    newer.last_scan = datetime(2026, 6, 1, 0, 0, tzinfo=timezone.utc)
+    db_session.add_all([older, newer])
+    await db_session.commit()
+
+    data = (await client.get("/api/v1/scan/pending", headers=headers)).json()[0]
+    assert data["node_created_at"].startswith("2026-01-01")  # oldest
+    assert data["node_last_scan"].startswith("2026-06-01")   # newest
+
+
 # --- Approve device ---
 
 @pytest.mark.asyncio
@@ -741,6 +792,75 @@ async def test_bulk_approve_approves_devices(client: AsyncClient, headers, two_p
     assert all(d["status"] == "approved" for d in inventory)
 
 
+@pytest.mark.asyncio
+async def test_bulk_approve_places_already_approved_device_on_another_design(
+    client: AsyncClient, headers, db_session, two_pending_devices
+):
+    """Regression: a device already approved (status='approved', e.g. placed on
+    another canvas) must still get a node on the design being approved onto.
+
+    Previously bulk-approve filtered status=='pending', so selecting an
+    already-approved device created no node — the user saw fewer nodes than
+    they selected."""
+    ids = [d.id for d in two_pending_devices]
+    design_a = await _add_design(db_session, "Canvas A")
+    design_b = await _add_design(db_session, "Canvas B")
+
+    # Approve both onto design A.
+    res_a = await client.post(
+        "/api/v1/scan/pending/bulk-approve",
+        json={"device_ids": ids, "design_id": design_a},
+        headers=headers,
+    )
+    assert res_a.json()["approved"] == 2
+
+    # Re-approve the same (now status='approved') devices onto design B.
+    res_b = await client.post(
+        "/api/v1/scan/pending/bulk-approve",
+        json={"device_ids": ids, "design_id": design_b},
+        headers=headers,
+    )
+    data_b = res_b.json()
+    assert data_b["approved"] == 2, "already-approved devices must place onto the new canvas"
+    assert data_b["skipped"] == 0
+
+    # Two nodes now exist on each design.
+    from app.db.models import Node as NodeModel
+    nodes_b = (
+        await db_session.execute(select(NodeModel).where(NodeModel.design_id == design_b))
+    ).scalars().all()
+    assert len(nodes_b) == 2
+
+
+@pytest.mark.asyncio
+async def test_bulk_approve_skips_device_already_on_target_design(
+    client: AsyncClient, headers, db_session, two_pending_devices
+):
+    """A device already on the target canvas (same ip) is not placed twice."""
+    ids = [d.id for d in two_pending_devices]
+    design = await _add_design(db_session, "Canvas")
+    # First device already sits on the canvas (matched by ip).
+    db_session.add(_node(design, ip="192.168.1.10"))
+    await db_session.commit()
+
+    res = await client.post(
+        "/api/v1/scan/pending/bulk-approve",
+        json={"device_ids": ids, "design_id": design},
+        headers=headers,
+    )
+    data = res.json()
+    assert data["approved"] == 1   # only the second device (192.168.1.11)
+    assert data["skipped"] == 1
+
+    from app.db.models import Node as NodeModel
+    nodes = (
+        await db_session.execute(select(NodeModel).where(NodeModel.design_id == design))
+    ).scalars().all()
+    # The pre-existing node plus the one newly approved — no duplicate for .10.
+    assert len(nodes) == 2
+    assert sorted(n.ip for n in nodes) == ["192.168.1.10", "192.168.1.11"]
+
+
 @pytest.fixture
 async def zigbee_pending_device(db_session):
     device = PendingDevice(
diff --git a/backend/tests/test_scanner.py b/backend/tests/test_scanner.py
index 2b02326..c493a7d 100644
--- a/backend/tests/test_scanner.py
+++ b/backend/tests/test_scanner.py
@@ -404,6 +404,84 @@ async def test_run_scan_adds_nmap_devices_as_pending(mem_db):
     assert any(d.ip == "192.168.1.5" for d in devices)
 
 
+@pytest.mark.asyncio
+async def test_run_scan_stamps_last_scan_on_matching_node_by_ip(mem_db):
+    """A scan that sees a device matching a canvas node (by IP) stamps last_scan."""
+    from app.services.scanner import run_scan
+
+    run_id = _make_run_id()
+    async with mem_db() as session:
+        session.add(_make_scan_run(run_id))
+        session.add(Node(id="n1", type="server", label="NAS", ip="192.168.1.5"))
+        await session.commit()
+
+    nmap_hosts = [{"ip": "192.168.1.5", "hostname": "nas.lan", "mac": None, "os": None, "open_ports": []}]
+
+    async with mem_db() as session:
+        with patch("app.services.scanner._nmap_scan", return_value=nmap_hosts), \
+             patch("app.services.scanner._mdns_discover", new_callable=AsyncMock, return_value=[]), \
+             patch("app.api.routes.status.broadcast_scan_update", new_callable=AsyncMock):
+            await run_scan(["192.168.1.0/24"], session, run_id)
+
+    async with mem_db() as session:
+        node = await session.get(Node, "n1")
+
+    assert node is not None
+    assert node.last_scan is not None
+
+
+@pytest.mark.asyncio
+async def test_run_scan_stamps_last_scan_on_matching_node_by_mac(mem_db):
+    """A node with no IP but a matching MAC still gets last_scan stamped."""
+    from app.services.scanner import run_scan
+
+    run_id = _make_run_id()
+    async with mem_db() as session:
+        session.add(_make_scan_run(run_id))
+        session.add(Node(id="n2", type="iot", label="Sensor", mac="AA:BB:CC:DD:EE:FF"))
+        await session.commit()
+
+    nmap_hosts = [{"ip": "192.168.1.9", "hostname": None, "mac": "AA:BB:CC:DD:EE:FF", "os": None, "open_ports": []}]
+
+    async with mem_db() as session:
+        with patch("app.services.scanner._nmap_scan", return_value=nmap_hosts), \
+             patch("app.services.scanner._mdns_discover", new_callable=AsyncMock, return_value=[]), \
+             patch("app.api.routes.status.broadcast_scan_update", new_callable=AsyncMock):
+            await run_scan(["192.168.1.0/24"], session, run_id)
+
+    async with mem_db() as session:
+        node = await session.get(Node, "n2")
+
+    assert node is not None
+    assert node.last_scan is not None
+
+
+@pytest.mark.asyncio
+async def test_run_scan_leaves_last_scan_untouched_on_unmatched_node(mem_db):
+    """A node whose IP/MAC is not seen by the scan keeps last_scan = None."""
+    from app.services.scanner import run_scan
+
+    run_id = _make_run_id()
+    async with mem_db() as session:
+        session.add(_make_scan_run(run_id))
+        session.add(Node(id="n3", type="server", label="Other", ip="10.0.0.99"))
+        await session.commit()
+
+    nmap_hosts = [{"ip": "192.168.1.5", "hostname": None, "mac": None, "os": None, "open_ports": []}]
+
+    async with mem_db() as session:
+        with patch("app.services.scanner._nmap_scan", return_value=nmap_hosts), \
+             patch("app.services.scanner._mdns_discover", new_callable=AsyncMock, return_value=[]), \
+             patch("app.api.routes.status.broadcast_scan_update", new_callable=AsyncMock):
+            await run_scan(["192.168.1.0/24"], session, run_id)
+
+    async with mem_db() as session:
+        node = await session.get(Node, "n3")
+
+    assert node is not None
+    assert node.last_scan is None
+
+
 @pytest.mark.asyncio
 async def test_run_scan_mdns_only_device_added(mem_db):
     """Devices found only by mDNS (not nmap) should appear in pending_devices."""
diff --git a/frontend/src/components/modals/PendingDeviceModal.tsx b/frontend/src/components/modals/PendingDeviceModal.tsx
index 542363b..d511dea 100644
--- a/frontend/src/components/modals/PendingDeviceModal.tsx
+++ b/frontend/src/components/modals/PendingDeviceModal.tsx
@@ -29,6 +29,12 @@ export interface PendingDevice {
   discovered_at: string
   // How many canvases (designs) this device already appears on. Computed server-side.
   canvas_count?: number
+  // Timestamps from the linked canvas node(s), correlated by ip/ieee_address.
+  // Null/absent when the device is not on any canvas yet.
+  node_created_at?: string | null
+  node_last_scan?: string | null
+  node_last_modified?: string | null
+  node_last_seen?: string | null
 }
 
 interface PendingDeviceModalProps {
diff --git a/frontend/src/components/modals/PendingDevicesModal.tsx b/frontend/src/components/modals/PendingDevicesModal.tsx
index b458fea..27b09f6 100644
--- a/frontend/src/components/modals/PendingDevicesModal.tsx
+++ b/frontend/src/components/modals/PendingDevicesModal.tsx
@@ -13,6 +13,7 @@ import type { NodeType, ServiceInfo } from '@/types'
 import { buildZigbeeProperties, isZigbeeType } from '@/utils/zigbeeProperties'
 import { buildZwaveProperties, isZwaveType } from '@/utils/zwaveProperties'
 import { buildMacProperty } from '@/utils/macProperty'
+import { formatRelative, formatTimestamp } from '@/utils/timeFormat'
 
 interface PendingDevicesModalProps {
   open: boolean
@@ -562,7 +563,7 @@ export function PendingDevicesModal({ open, onClose, highlightId, initialStatus
               </p>
             )}
             {!loading && filtered.length > 0 && (
-              <div className="grid grid-cols-1 lg:grid-cols-2 2xl:grid-cols-3 gap-3">
+              <div className="grid grid-cols-1 md:grid-cols-2 xl:grid-cols-3 gap-2">
                 {filtered.map((d) => (
                   <DeviceCard
                     key={d.id}
@@ -663,6 +664,22 @@ function DeviceCard({ device, selected, selectMode, highlighted, onClick, cardRe
   const visibleServices = services.slice(0, 4)
   const moreServices = services.length - visibleServices.length
 
+  // Timestamps: a device placed on a canvas shows its linked node's lifecycle
+  // (created / last scan / last modified / last seen). A device that is only in
+  // the discovery inventory has no node yet, so it falls back to when the
+  // scanner first saw it.
+  const onCanvas = (device.canvas_count ?? 0) > 0
+  const timestamps: { label: string; iso: string }[] = []
+  if (onCanvas) {
+    if (device.node_created_at) timestamps.push({ label: 'Created', iso: device.node_created_at })
+    if (device.node_last_scan) timestamps.push({ label: 'Scan', iso: device.node_last_scan })
+    if (device.node_last_modified) timestamps.push({ label: 'Modified', iso: device.node_last_modified })
+    if (device.node_last_seen) timestamps.push({ label: 'Seen', iso: device.node_last_seen })
+  }
+  if (timestamps.length === 0) {
+    timestamps.push({ label: 'Discovered', iso: device.discovered_at })
+  }
+
   const borderClass = highlighted
     ? 'border-[#e3b341] bg-[#2d3748]'
     : selected
@@ -674,7 +691,7 @@ function DeviceCard({ device, selected, selectMode, highlighted, onClick, cardRe
       ref={cardRef}
       onClick={onClick}
       data-testid={`pending-card-${device.id}`}
-      className={`relative text-left rounded-lg border p-3 transition-all duration-150 ${borderClass}`}
+      className={`relative text-left rounded-lg border p-2.5 transition-all duration-150 ${borderClass}`}
     >
       {selectMode && selected && (
         <CheckCircle2
@@ -759,6 +776,14 @@ function DeviceCard({ device, selected, selectMode, highlighted, onClick, cardRe
           )}
         </div>
       )}
+
+      {/* Timestamps — compact relative times, full date on hover. Kept tiny so
+          the tile footprint stays the same as before. */}
+      <div className="mt-2 pt-2 border-t border-border/50 grid grid-cols-2 gap-x-2 gap-y-0.5 text-[10px]">
+        {timestamps.map((t) => (
+          <TimeLine key={t.label} label={t.label} iso={t.iso} />
+        ))}
+      </div>
     </button>
   )
 }
@@ -771,3 +796,12 @@ function InfoLine({ label, value }: { label: string; value: string }) {
     </div>
   )
 }
+
+function TimeLine({ label, iso }: { label: string; iso: string }) {
+  return (
+    <div className="flex items-baseline gap-1 min-w-0" title={formatTimestamp(iso)}>
+      <span className="text-muted-foreground shrink-0">{label}</span>
+      <span className="font-mono text-foreground/80 truncate">{formatRelative(iso)}</span>
+    </div>
+  )
+}
diff --git a/frontend/src/components/modals/__tests__/PendingDevicesModal.test.tsx b/frontend/src/components/modals/__tests__/PendingDevicesModal.test.tsx
index 92baef6..25b27be 100644
--- a/frontend/src/components/modals/__tests__/PendingDevicesModal.test.tsx
+++ b/frontend/src/components/modals/__tests__/PendingDevicesModal.test.tsx
@@ -1,5 +1,5 @@
 import { describe, it, expect, beforeEach, vi } from 'vitest'
-import { render, screen, fireEvent, waitFor } from '@testing-library/react'
+import { render, screen, fireEvent, waitFor, within } from '@testing-library/react'
 import { PendingDevicesModal } from '../PendingDevicesModal'
 import { useCanvasStore } from '@/stores/canvasStore'
 
@@ -364,4 +364,37 @@ describe('PendingDevicesModal', () => {
     expect(screen.queryByTestId('pending-card-dev-b')).not.toBeInTheDocument()
     expect(screen.getByTestId('pending-card-dev-a')).toBeInTheDocument()
   })
+
+  describe('tile timestamps', () => {
+    it('shows the linked node lifecycle timestamps for on-canvas devices', async () => {
+      mockPending.mockResolvedValue({
+        data: [{
+          ...DEVICE_IP,
+          canvas_count: 1,
+          node_created_at: '2026-01-02T10:00:00Z',
+          node_last_scan: '2026-06-01T08:30:00Z',
+          node_last_modified: '2026-06-20T12:00:00Z',
+          node_last_seen: '2026-06-25T09:15:00Z',
+        }],
+      })
+      render(<PendingDevicesModal {...baseProps} />)
+      const card = await screen.findByTestId('pending-card-dev-a')
+      const inCard = within(card)
+      expect(inCard.getByText('Created')).toBeInTheDocument()
+      expect(inCard.getByText('Scan')).toBeInTheDocument()
+      expect(inCard.getByText('Modified')).toBeInTheDocument()
+      expect(inCard.getByText('Seen')).toBeInTheDocument()
+      // Discovered fallback is not shown once node timestamps are present.
+      expect(inCard.queryByText('Discovered')).not.toBeInTheDocument()
+    })
+
+    it('falls back to Discovered for devices not on any canvas', async () => {
+      mockPending.mockResolvedValue({ data: [DEVICE_IP] })
+      render(<PendingDevicesModal {...baseProps} />)
+      const card = await screen.findByTestId('pending-card-dev-a')
+      const inCard = within(card)
+      expect(inCard.getByText('Discovered')).toBeInTheDocument()
+      expect(inCard.queryByText('Created')).not.toBeInTheDocument()
+    })
+  })
 })
diff --git a/frontend/src/components/panels/DetailPanel.tsx b/frontend/src/components/panels/DetailPanel.tsx
index 7b5f748..b75ff31 100644
--- a/frontend/src/components/panels/DetailPanel.tsx
+++ b/frontend/src/components/panels/DetailPanel.tsx
@@ -8,6 +8,7 @@ import { NODE_TYPE_LABELS, STATUS_COLORS, type ServiceInfo, type ServiceStatus,
 import { getServiceUrl } from '@/utils/serviceUrl'
 import { splitIps } from '@/utils/maskIp'
 import { PROPERTY_ICONS, PROPERTY_ICON_NAMES, resolvePropertyIcon } from '@/utils/propertyIcons'
+import { formatTimestamp } from '@/utils/timeFormat'
 import type { Node } from '@xyflow/react'
 
 interface DetailPanelProps {
@@ -252,7 +253,10 @@ export function DetailPanel({ onEdit }: DetailPanelProps) {
         {data.mac && <DetailRow label="MAC" value={data.mac} mono />}
         {data.os && <DetailRow label="OS" value={data.os} />}
         {data.check_method && <DetailRow label="Check" value={data.check_method} mono />}
-        {data.last_seen && <DetailRow label="Last Seen" value={new Date(/[Zz]|[+-]\d{2}:?\d{2}$/.test(data.last_seen) ? data.last_seen : data.last_seen + 'Z').toLocaleString()} />}
+        {data.last_seen && <DetailRow label="Last Seen" value={formatTimestamp(data.last_seen)} />}
+        {data.last_scan && <DetailRow label="Last Scan" value={formatTimestamp(data.last_scan)} />}
+        {data.created_at && <DetailRow label="Created" value={formatTimestamp(data.created_at)} />}
+        {data.updated_at && <DetailRow label="Last Modified" value={formatTimestamp(data.updated_at)} />}
       </div>
 
       {/* Size section — manual width/height entry for pixel-exact sizing */}
diff --git a/frontend/src/components/panels/__tests__/DetailPanel.test.tsx b/frontend/src/components/panels/__tests__/DetailPanel.test.tsx
index e81e1d5..03b5982 100644
--- a/frontend/src/components/panels/__tests__/DetailPanel.test.tsx
+++ b/frontend/src/components/panels/__tests__/DetailPanel.test.tsx
@@ -212,6 +212,37 @@ describe('DetailPanel', () => {
     })
   })
 
+  describe('Inventory timestamps', () => {
+    it('renders Created, Last Scan and Last Modified rows when present', () => {
+      setupStore({
+        created_at: '2026-01-02T10:00:00Z',
+        last_scan: '2026-06-01T08:30:00Z',
+        updated_at: '2026-06-20T12:00:00Z',
+        last_seen: '2026-06-25T09:15:00Z',
+      })
+      render(<DetailPanel onEdit={vi.fn()} />)
+      expect(screen.getByText('Created')).toBeInTheDocument()
+      expect(screen.getByText('Last Scan')).toBeInTheDocument()
+      expect(screen.getByText('Last Modified')).toBeInTheDocument()
+      expect(screen.getByText('Last Seen')).toBeInTheDocument()
+    })
+
+    it('omits rows whose timestamps are absent', () => {
+      setupStore({ created_at: '2026-01-02T10:00:00Z' })
+      render(<DetailPanel onEdit={vi.fn()} />)
+      expect(screen.getByText('Created')).toBeInTheDocument()
+      expect(screen.queryByText('Last Scan')).not.toBeInTheDocument()
+      expect(screen.queryByText('Last Modified')).not.toBeInTheDocument()
+    })
+
+    it('parses naive (suffix-less) UTC timestamps without throwing', () => {
+      setupStore({ created_at: '2026-01-02 10:00:00' })
+      render(<DetailPanel onEdit={vi.fn()} />)
+      // Renders a locale string for the date (year is locale-independent).
+      expect(screen.getByText(/2026/)).toBeInTheDocument()
+    })
+  })
+
   describe('Panel actions', () => {
     it('calls setSelectedNode(null) when close button is clicked', () => {
       const setSelectedNode = vi.fn()
diff --git a/frontend/src/types/index.ts b/frontend/src/types/index.ts
index 22132b7..7f438fb 100644
--- a/frontend/src/types/index.ts
+++ b/frontend/src/types/index.ts
@@ -102,6 +102,9 @@ export interface NodeData extends Record<string, unknown> {
   check_target?: string
   services: ServiceInfo[]
   last_seen?: string
+  last_scan?: string
+  created_at?: string
+  updated_at?: string
   response_time_ms?: number
   notes?: string
   cpu_count?: number
diff --git a/frontend/src/utils/__tests__/timeFormat.test.ts b/frontend/src/utils/__tests__/timeFormat.test.ts
new file mode 100644
index 0000000..8fd2635
--- /dev/null
+++ b/frontend/src/utils/__tests__/timeFormat.test.ts
@@ -0,0 +1,53 @@
+import { describe, it, expect } from 'vitest'
+import { formatTimestamp, formatRelative } from '../timeFormat'
+
+describe('formatTimestamp', () => {
+  it('parses an ISO string with a Z suffix', () => {
+    expect(formatTimestamp('2026-01-02T10:00:00Z')).toContain('2026')
+  })
+
+  it('treats a suffix-less timestamp as UTC (appends Z)', () => {
+    // Same instant expressed with and without the explicit Z must match.
+    expect(formatTimestamp('2026-01-02 10:00:00')).toBe(formatTimestamp('2026-01-02T10:00:00Z'))
+  })
+})
+
+describe('formatRelative', () => {
+  const now = Date.parse('2026-06-27T12:00:00Z')
+
+  it('returns "just now" for sub-minute deltas', () => {
+    expect(formatRelative('2026-06-27T11:59:30Z', now)).toBe('just now')
+  })
+
+  it('formats minutes', () => {
+    expect(formatRelative('2026-06-27T11:45:00Z', now)).toBe('15m ago')
+  })
+
+  it('formats hours', () => {
+    expect(formatRelative('2026-06-27T09:00:00Z', now)).toBe('3h ago')
+  })
+
+  it('formats days', () => {
+    expect(formatRelative('2026-06-25T12:00:00Z', now)).toBe('2d ago')
+  })
+
+  it('formats weeks', () => {
+    expect(formatRelative('2026-06-06T12:00:00Z', now)).toBe('3w ago')
+  })
+
+  it('formats months', () => {
+    expect(formatRelative('2026-02-27T12:00:00Z', now)).toBe('4mo ago')
+  })
+
+  it('formats years', () => {
+    expect(formatRelative('2024-06-27T12:00:00Z', now)).toBe('2y ago')
+  })
+
+  it('clamps future timestamps to "just now"', () => {
+    expect(formatRelative('2026-06-27T12:05:00Z', now)).toBe('just now')
+  })
+
+  it('handles suffix-less (naive UTC) input', () => {
+    expect(formatRelative('2026-06-27 11:45:00', now)).toBe('15m ago')
+  })
+})
diff --git a/frontend/src/utils/timeFormat.ts b/frontend/src/utils/timeFormat.ts
new file mode 100644
index 0000000..7b482d1
--- /dev/null
+++ b/frontend/src/utils/timeFormat.ts
@@ -0,0 +1,36 @@
+// Shared timestamp formatting. Backend timestamps may arrive without a timezone
+// suffix (naive UTC); append 'Z' when absent so the browser parses them as UTC
+// rather than local time.
+
+function toUtcIso(value: string): string {
+  return /[Zz]|[+-]\d{2}:?\d{2}$/.test(value) ? value : value + 'Z'
+}
+
+/** Full locale date+time, e.g. for tooltips and the detail panel. */
+export function formatTimestamp(value: string): string {
+  return new Date(toUtcIso(value)).toLocaleString()
+}
+
+/**
+ * Compact relative time, e.g. "just now", "5m ago", "3h ago", "2d ago",
+ * "4w ago", "5mo ago", "2y ago". Future timestamps clamp to "just now".
+ * `now` is injectable for deterministic tests.
+ */
+export function formatRelative(value: string, now: number = Date.now()): string {
+  const then = new Date(toUtcIso(value)).getTime()
+  if (Number.isNaN(then)) return ''
+  const sec = Math.floor((now - then) / 1000)
+  if (sec < 60) return 'just now'
+  const min = Math.floor(sec / 60)
+  if (min < 60) return `${min}m ago`
+  const hr = Math.floor(min / 60)
+  if (hr < 24) return `${hr}h ago`
+  const day = Math.floor(hr / 24)
+  if (day < 7) return `${day}d ago`
+  const week = Math.floor(day / 7)
+  if (week < 5) return `${week}w ago`
+  const month = Math.floor(day / 30)
+  if (month < 12) return `${month}mo ago`
+  const year = Math.floor(day / 365)
+  return `${year}y ago`
+}