How long an on-demand model holds a card is a live setting

On one card shared by flux and sf3d, a mesh asked for after a picture
waited out the picture model's five minutes of protection and two of idle.
on_demand.evict_after_idle and on_demand.min_lifetime set those for the
cluster, in force on the leader as they change; unset keeps 2m and 5m.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

docs/reference.md

@@ -205,6 +205,8 @@ rather than repeated.
 | `no_passwords` | `bool` | [OIDC](#oidc) |
 | `mirror` | `string` | [Offline](#offline) |
 | `checksums` | `string` | [Offline](#offline) |
+| `evict_after_idle` | `time.Duration` | [OnDemandSettings](#ondemandsettings) |
+| `min_lifetime` | `time.Duration` | [OnDemandSettings](#ondemandsettings) |
 | `nvidia_smi` | `string` | [Options](#options) |
 | `ib_root` | `string` | [Options](#options) |
 | `prefer_nvml` | `bool` | [Options](#options) |
@@ -346,6 +348,7 @@ rather than repeated.
 | `serving` | `ServingSettings` | [Server](#server) |
 | `firewall` | `FirewallSettings` | [Server](#server) |
 | `presets` | `PresetSettings` | [Server](#server) |
+| `on_demand` | `OnDemandSettings` | [Server](#server) |
 | `agents` | `AgentSettings` | [Server](#server) |
 | `firewall_networks` | `[]string` | [Server](#server) |
 | `backup_recipients` | `[]string` | [Server](#server) |
@@ -1912,6 +1915,25 @@ kept by llmgw bundle import and llmgw bundle trust; every engine file
 a node fetches from the mirror is checked against it. Read again
 whenever it changes. Empty is /etc/llmgw/offline.sha256.
 
+## OnDemandSettings
+
+### `evict_after_idle`
+
+`time.Duration`
+
+EvictAfterIdle is how long an on-demand replica must go unasked-for
+before a model that wants its card may have it. Zero keeps 2m.
+
+### `min_lifetime`
+
+`time.Duration`
+
+MinLifetime is how long a replica that has just come up is safe from
+that, so two models do not take turns paying for loads. Zero keeps
+5m. On one card shared by a picture model and a 3D model, 1m each
+brings the wait between a picture and its mesh to about a minute.
+Both are in force on the leader within seconds.
+
 ## Options
 
 ### `nvidia_smi`
@@ -2984,6 +3006,15 @@ Presets is how the models that come with llmgw reach the catalog.
 
 Takes a [PresetSettings](#presetsettings) block.
 
+### `on_demand`
+
+`OnDemandSettings`
+
+OnDemand is how models that load when asked for take turns on the
+cards.
+
+Takes a [OnDemandSettings](#ondemandsettings) block.
+
 ### `agents`
 
 `AgentSettings`