Slurm beside llmgw, P1: its settings and the files a controller runs on

slurm.{enabled,cluster_name,controller,nodes,lent,partition} in the cluster's
settings, checked; internal/slurm writes slurm.conf (configless), gres.conf
and cgroup.conf from the nodes' slurmd -C lines and GPUs, derives the munge
key from a cluster secret, and reads scontrol and version output.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/reference.md

@@ -376,6 +376,7 @@ rather than repeated.
 | `mail` | `mail.Config` | [Server](#server) |
 | `serving` | `ServingSettings` | [Server](#server) |
 | `firewall` | `FirewallSettings` | [Server](#server) |
+| `slurm` | `SlurmSettings` | [Server](#server) |
 | `presets` | `PresetSettings` | [Server](#server) |
 | `on_demand` | `OnDemandSettings` | [Server](#server) |
 | `agents` | `AgentSettings` | [Server](#server) |
@@ -401,6 +402,12 @@ rather than repeated.
 | `timeout` | `time.Duration` | [Service](#service) |
 | `stopped` | `bool` | [ServingSettings](#servingsettings) |
 | `bin` | `string` | [SimConfig](#simconfig) |
+| `enabled` | `bool` | [SlurmSettings](#slurmsettings) |
+| `cluster_name` | `string` | [SlurmSettings](#slurmsettings) |
+| `controller` | `string` | [SlurmSettings](#slurmsettings) |
+| `nodes` | `[]string` | [SlurmSettings](#slurmsettings) |
+| `lent` | `[]string` | [SlurmSettings](#slurmsettings) |
+| `partition` | `string` | [SlurmSettings](#slurmsettings) |
 | `dir` | `string` | [StrataConfig](#strataconfig) |
 | `python` | `string` | [StrataConfig](#strataconfig) |
 | `engine` | `string` | [StrataConfig](#strataconfig) |
@@ -3279,6 +3286,15 @@ Firewall turns llmgw's firewall on every machine on or off.
 
 Takes a [FirewallSettings](#firewallsettings) block.
 
+### `slurm`
+
+`SlurmSettings`
+
+Slurm is a Slurm cluster run beside llmgw on some of its nodes, and
+which of them it may use now.
+
+Takes a [SlurmSettings](#slurmsettings) block.
+
 ### `presets`
 
 `PresetSettings`
@@ -3480,6 +3496,50 @@ entries ask. In force on every control plane within seconds.
 Bin is the llmgw binary itself; the engine is one of its subcommands.
 Empty means whatever started this agent, which is right almost always.
 
+## SlurmSettings
+
+### `enabled`
+
+`bool`
+
+Enabled runs Slurm on the nodes below. False stops llmgw keeping it;
+what was installed is left installed, and every node is llmgw's.
+
+### `cluster_name`
+
+`string`
+
+ClusterName is Slurm's ClusterName. Empty is "llmgw".
+
+### `controller`
+
+`string`
+
+Controller is the llmgw node whose agent runs slurmctld. It needs no
+GPU, and need not be one of Nodes.
+
+### `nodes`
+
+`[]string`
+
+Nodes are the llmgw nodes that run slurmd. Each stays llmgw's, drained
+in Slurm, until it is also in Lent.
+
+### `lent`
+
+`[]string`
+
+Lent are the nodes of Nodes Slurm may run jobs on now. A node put here
+is drained of llmgw's replicas first, as `ctl drain` does, and resumed
+in Slurm once none is left; a node taken out is drained in Slurm and
+given back to llmgw when its last job ends.
+
+### `partition`
+
+`string`
+
+Partition is the one partition every node is in. Empty is "gpu".
+
 ## StrataConfig
 
 ### `dir`