Models that know about each other, and have a self

Three features sharing one idea: a model here started from nothing every
conversation and had no notion that anything else existed.

THE ROSTER. `chat.roster_block` builds one line per model this *person* can
reach -- through `permissions.models_visible_to`, never the table -- and
`{{model_roster}}` carries it, gated on the `friend` family for the reason the
memories block is gated on `memory`: a list of peers a model cannot talk to is
context spent on nothing, and one checkbox is then the whole switch. New
`Model.notes` column, a column and not a `capabilities_json` key for the reason
`context_length` and `reasoning_efforts` both carry.

ASKING A FRIEND. A second entry point in `services/subagent.py` rather than a
second module, so one place still owns the bounds and the lifecycle. `_create_
child` takes the friend's (model_id, connection_id) *pair*, because Model is
unique on both and an id alone does not say which endpoint. Three things differ
from a helper: the effort is the friend's own default and never the parent's (the
1.3.0 bug by another door -- the vocabularies differ and a level a model does not
take raises inside its chat template), the chat is ordinary even when the asker's
is an agent chat, and `scope_json["role"]` marks it so `core.friend` speaks
instead of `core.subagent`. `friend` joins the unattended withdrawal set: a
friend that could ask a friend is the same unbounded fan-out in politer clothes.
Budget, concurrency and quota are shared with helpers, so one reply cannot spend
the allowance twice.

PERSONALITY. One table, two roles, `owner_id IS NULL` the discriminator: the
model's own persona, and its read of one person. Keyed on the model's *text* id
with no foreign key, because "Test & refresh" deletes a model the endpoint has
stopped listing and a personality must not be collateral. `PersonaRevision`
copies SkillRevision, and so does the argument: the safety story for a model
rewriting itself is a record and a way back, not a gate. The reflection is shown
to the person it is about, in their own settings, which is the whole of why
keeping one is acceptable. `persona` is withdrawn from any unattended chat --
a helper's task, a friend's question and a schedule's instruction are all words
nobody watched being written.

Two bugs found while reading for this, both silent:

`review_model_id` stored a `Model` primary key, so a refresh taken while an
endpoint was not listing that model unset the administrator's choice -- and
`_reviewer` then fell back to the chat's own model, so pictures were judged by
a model nobody chose. Now the text id, with the primary key still accepted.

`_messages_after` used a bare `>` on `created_at`, so a row sharing the edited
turn's microsecond survived a rewind -- and `_send` writes a user turn and its
placeholder back to back, which is exactly that tie. Deliberately NOT
`thread_tail`'s `(created_at, id)` tiebreak: ids are random UUIDs, so that
settles a tie by coin toss. A tie now reads as "later", which is the safe
direction for an operation whose purpose is to discard what follows.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/lembas/web/templates/admin/agents.html

@@ -454,6 +454,13 @@
       research fan out instead of queueing. This applies to ordinary chats as
       much as agent ones.
     </p>
+    <p class="field__hint">
+      <strong>Asking another model a question uses the same switch and the same
+      allowance below</strong>, because it costs the same thing: one reply
+      setting another reply going. Which people may do it is a separate
+      permission — <strong>Ask another model</strong> — and which models may is a
+      switch on each model's own page.
+    </p>
 
     <div class="alert">
       {{ icon("shield", "icon--sm") }}
@@ -482,13 +489,17 @@
     </div>
 
     <div class="field">
-      <label class="field__label" for="sub_max_per_reply">Most helpers one reply may send</label>
+      <label class="field__label" for="sub_max_per_reply">
+        Most helpers one reply may send
+      </label>
       <input class="input" id="sub_max_per_reply" name="max_per_reply"
              type="number" min="1" max="20" step="1"
              value="{{ subagents.max_per_reply }}">
       <p class="field__hint">
         Fanning out across a handful of independent questions is what this is
-        for. A reply that wants twenty has misread the tool.
+        for. A reply that wants twenty has misread the tool. Questions put to
+        other models count against this same number, so one reply cannot spend
+        the allowance twice.
       </p>
     </div>