CAT-N1: the bus module's keeper, its own events stream, state and the seat's reading verbs in the manifest

The keeper is a process of the tools bundle on its own account (own secret
broker-keeper, ADR 0436 §1): it hears the indexer's manifest-accepted, keeps
what it heard in its old state asked and the persons' requests in requests
(ADR 0595 §10), and says its nine events on its own stream broker-events,
30 days at 256 MiB (design 25 § 12.3, ADR 0620 §2). mesh-broker serves its
four reading verbs; its acting verbs are the keeper's own work. The server
gains a tcp check, which the keeper's tool check stands beside.

Claude-Session: https://claude.ai/code/session_01JG73KJNrH5EgFXMKKYSrig

modules/nats/module.json

@@ -24,14 +24,24 @@
   "claims": [
     {
       "name": "mesh-broker",
-      "scope": "mesh"
+      "scope": "mesh",
+      "serves": [
+        "list",
+        "show",
+        "check",
+        "orphans"
+      ]
     }
   ],
   "bus-users": "/var/lib/nats-module/conf/accounts.conf",
   "core-credentials": true,
   "own-secrets": {
     "broker": "${dir:mesh-state}/broker",
-    "broker-nats-tools": "${dir:tools-secret}/broker-nats-tools"
+    "broker-nats-tools": "${dir:tools-secret}/broker-nats-tools",
+    "broker-keeper": {
+      "path": "${dir:keeper-state}/broker-keeper",
+      "owner": "nats-keeper"
+    }
   },
   "capabilities": [
     "container-runtime"
@@ -43,16 +53,51 @@
     "bucket-expiry-set"
   ],
   "invokes": [
-    "seat:mesh-hand-acts.hand-act"
+    "seat:mesh-hand-acts.hand-act",
+    "mesh-delivery-indexer.indexer_bus_state"
+  ],
+  "consumes": [
+    "mesh-delivery-indexer.manifest-accepted"
+  ],
+  "uses": [
+    "operator-channel"
+  ],
+  "streams": [
+    {
+      "name": "broker-events",
+      "events": [
+        "created",
+        "refused",
+        "drifted",
+        "drift-cleared",
+        "full",
+        "full-cleared",
+        "orphaned",
+        "recreated",
+        "dropped"
+      ],
+      "max-age-days": 30,
+      "max-mib": 256
+    }
+  ],
+  "state": [
+    {
+      "name": "asked",
+      "history": 5
+    },
+    {
+      "name": "requests",
+      "history": 5,
+      "ttl-seconds": 86400
+    }
   ],
-  "consumes": [],
   "listens": [
     {
       "name": "bus",
       "port": 4222,
       "protocol": "tcp",
       "from": "mesh",
-      "why": "the mesh bus — every link the mesh has, over TLS, reached across the overlay"
+      "why": "the mesh bus \u2014 every link the mesh has, over TLS, reached across the overlay"
     }
   ],
   "tools": [
@@ -96,6 +141,13 @@
     ]
   },
   "resources": [
+    {
+      "id": "keeper-account",
+      "type": "user",
+      "name": "nats-keeper",
+      "shell": "/usr/bin/nologin",
+      "home": "/var/lib/nats-keeper"
+    },
     {
       "id": "jetstream-data",
       "type": "directory",
@@ -117,6 +169,14 @@
       "mode": "0711",
       "unknown": "program"
     },
+    {
+      "id": "keeper-state",
+      "type": "directory",
+      "path": "/var/lib/nats-keeper",
+      "mode": "0700",
+      "owner": "nats-keeper",
+      "unknown": "program"
+    },
     {
       "id": "snapshots",
       "type": "directory",
@@ -158,6 +218,41 @@
       "artifact": "entrypoint",
       "unknown": "program"
     },
+    {
+      "id": "keeper",
+      "type": "process",
+      "name": "nats-keeper",
+      "artifact": "tools",
+      "run": [
+        "./nats-tools",
+        "keep"
+      ],
+      "user": "nats-keeper",
+      "env": {
+        "MESH_BROKER_FILE": "${dir:keeper-state}/broker-keeper",
+        "MESH_NATS_FULL_RAISE": "75",
+        "MESH_NATS_FULL_CLEAR": "70"
+      },
+      "bus": {
+        "state": [
+          "asked",
+          "requests"
+        ],
+        "asks": true,
+        "invokes": [
+          "mesh-delivery-indexer.indexer_bus_state",
+          "seat:mesh-hand-acts.hand-act"
+        ]
+      },
+      "health": {
+        "kind": "tool",
+        "tool": "nats_keeper_health",
+        "interval": "60s",
+        "timeout": "10s",
+        "looks": 2,
+        "grace": "180s"
+      }
+    },
     {
       "id": "server",
       "type": "container",
@@ -181,7 +276,11 @@
       "restart-on": [
         "program-snapshot",
         "program-entrypoint"
-      ]
+      ],
+      "health": {
+        "kind": "tcp",
+        "endpoint": "bus"
+      }
     }
   ],
   "accesses": [