Reservation lease time; reservations by MAC address or client ID

- A reservation can have its own lease time (--lease-time, the
  reservation dialog), over the subnet's. Schema migration 6.
- A reservation with a MAC address and a client ID matches either one
  (a dual-boot machine sends two client IDs from one MAC); before, it
  was found by MAC and then refused. A lease of the reserved address by
  the client's other identity counts as its own.
- The Leases page shows a client's client ID; reserving a lease uses
  both, or one with --by / the dialog's choice.

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

docs/api.md

@@ -111,7 +111,7 @@ out. `lease_time` 0 means the settings'.
 | | |
 |---|---|
 | `GET /reservations[?subnet=REF]` | each with `subnet_id`, `subnet` and its current `lease` |
-| `POST /reservations` | `{"ip", "mac", "client_id", "hostname", "options", "disabled", "comment"}`; `ip` and `mac` or `client_id` needed |
+| `POST /reservations` | `{"ip", "mac", "client_id", "hostname", "options", "lease_time", "disabled", "comment"}`; `ip` and `mac` or `client_id` needed (with both, either matches); `lease_time` 0 is the subnet's |
 | `GET`, `PATCH`, `DELETE /reservations/{ref}` | by ID, address, or MAC address (when it has one reservation) |
 
 ### Leases and activity
@@ -121,7 +121,7 @@ out. `lease_time` 0 means the settings'.
 | `GET /leases[?subnet=&state=&interface=&q=]` | every lease, with its state now (`active`, `expired`, `released`, `declined`), `subnet` and its reservation, and `last_seen` when the client last answered a ping (left out if it never has); `q` searches address, MAC and host name |
 | `GET /leases/{ip}` | one |
 | `DELETE /leases/{ip}` | forget it (audited) |
-| `POST /leases/{ip}/reserve` | make it a reservation; optional `{"hostname", "comment"}` |
+| `POST /leases/{ip}/reserve` | make it a reservation; optional `{"hostname", "comment", "by"}`, `by` being `mac`, `client_id` or `both` (the default) |
 | `GET /events[?mac=&subnet=&interface=&limit=]` | the latest DHCP messages, newest first (the last 1000 are kept in memory). `subnet` (ID, name or prefix) keeps messages for its addresses, and those without an address on its interface |
 
 ### History and import

docs/cli.md

@@ -77,8 +77,8 @@ one. An option Steward doesn't know: `--option 224:string=hello`.
 |---|---|
 | `reservation list [--subnet SUBNET]` | reservations, whether each client is online, and when it last answered a ping |
 | `reservation show RES` | RES is its ID, address or MAC address |
-| `reservation add IP MAC [--hostname H] [--client-id HEX] [--option NAME=VALUE]... [--comment C]` | `-` for MAC with `--client-id` |
-| `reservation update RES [--ip] [--mac] [--client-id] [--hostname] [--option]... [--unset-option]... [--comment]` | |
+| `reservation add IP MAC [--hostname H] [--client-id HEX] [--lease-time 7d] [--option NAME=VALUE]... [--comment C]` | `-` for MAC with `--client-id`; with both, either matches |
+| `reservation update RES [--ip] [--mac] [--client-id] [--hostname] [--lease-time 7d\|default] [--option]... [--unset-option]... [--comment]` | |
 | `reservation enable\|disable RES` | use a reservation, or keep it but ignore it |
 | `reservation delete RES` | |
 
@@ -88,7 +88,7 @@ one. An option Steward doesn't know: `--option 224:string=hello`.
 |---|---|
 | `lease list [--subnet S] [--state STATE] [--interface I] [--search TEXT] [-a]` | active and held-back leases; `-a` all |
 | `lease show IP` | one lease |
-| `lease reserve IP [--hostname H]` | make the address its client's reservation |
+| `lease reserve IP [--hostname H] [--by mac\|client-id\|both]` | make the address its client's reservation, by its MAC address and client ID (either matches) unless `--by` says one |
 | `lease delete IP [-y]` | free the address at once |
 
 ### activity

docs/subnets.md

@@ -58,15 +58,20 @@ steward reservation add 10.0.10.20 aa:bb:cc:dd:ee:01 --hostname nas
 steward lease reserve 10.0.10.57       # the address a client has now
 ```
 
-* **The client** is known by its MAC address, or by its client identifier
-  (option 61) when the reservation has one (`--client-id`; give `-` as the
-  MAC). Some devices change their identifier but not their MAC address,
-  and others the other way round. When unsure, use the MAC address.
+* **The client** is known by its MAC address, its client identifier
+  (option 61, `--client-id`; give `-` as the MAC for an identifier alone),
+  or both. With both, **either one** gets the client its address: a
+  machine that boots two systems sends different identifiers from one MAC
+  address, and a device with a randomised MAC may keep its identifier.
+  The Leases page and `steward lease show` show the identifier a client
+  sent; `steward lease reserve IP` uses both when it sent one (`--by mac`
+  or `--by client-id` for just one).
 * **The address picks the subnet**: the subnet whose network holds it. It
   may be inside a pool or outside one; either way, nobody else gets it.
 * **The host name** is sent to the client (option 12).
 * **Options** set on the reservation are for that client only, and win
   over the subnet's and the settings'.
+* **A lease time** of its own (`--lease-time 7d`) wins over the subnet's.
 * **A device on two VLANs** can have a reservation in each subnet. Within
   one subnet, a client has at most one.
 
@@ -108,7 +113,9 @@ a list, it gets every option set for it.
 ## Lease times
 
 The settings have the default (12 hours, `steward settings set
---lease-time 1d`); a subnet can have its own (`--lease-time 1h`). Clients
+--lease-time 1d`); a subnet can have its own (`--lease-time 1h`), and a
+reservation its own over that (`steward reservation update nas
+--lease-time 7d`). Clients
 renew halfway through. Short times let changes reach clients sooner;
 long ones keep clients working longer if Steward is down.