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 `persona` is withdrawn from any unattended chat --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>

tests/test_agent_policy.py

@@ -270,6 +270,14 @@ def test_the_builtins_that_change_things_say_so():
         # class as a note. Plan mode meaning "look but do not touch" has to mean
         # this too, even though what it touches is a page rather than a machine.
         "report_write",
+        # Its own character and its own read of the person. Writes for the same
+        # reason `report_write` is one, and more strongly: these outlive the
+        # conversation, are carried into every later one, and change how it
+        # behaves rather than only what is recorded. Being in this set is also
+        # what makes `scope_json["write"] = False` withdraw them, which is how a
+        # read-only helper is kept from rewriting who it is.
+        "persona_write",
+        "impression_write",
     }