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 `persona` is withdrawn from any unattended chat --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/db/models/__init__.py

@@ -62,6 +62,7 @@ from lembas.db.models.library import (
     SkillRevision,
     chat_knowledge_bases,
 )
+from lembas.db.models.persona import Persona, PersonaRevision
 from lembas.db.models.report import (
     SOURCE_CHAT,
     SOURCE_MANUAL,
@@ -178,6 +179,8 @@ __all__ = [
     "KnowledgeBase",
     "McpServer",
     "Memory",
+    "Persona",
+    "PersonaRevision",
     "Message",
     "Model",
     "Note",

src/lembas/db/models/connection.py

@@ -101,6 +101,16 @@ class Model(UUIDPrimaryKey, Timestamps, Base):
     model_id: Mapped[str] = mapped_column(String(300), nullable=False)
     display_name: Mapped[str] = mapped_column(String(300), default="")
     description: Mapped[str] = mapped_column(Text, default="")
+
+    # What the *other* models are told about this one, when the roster is in
+    # front of them. Separate from `description`, which is written for people
+    # and reads like marketing; this is meant to be facts -- parameters,
+    # quantisation, a benchmark figure, what it is bad at.
+    #
+    # A column and not a key in `capabilities_json`, for the reason
+    # `context_length` and `reasoning_efforts` both carry: that dict is rebuilt
+    # wholesale from the submitted checkboxes on every save.
+    notes: Mapped[str] = mapped_column(Text, default="")
     enabled: Mapped[bool] = mapped_column(Boolean, default=True, nullable=False)
 
     # Sort order in every picker. Ties fall back to model_id so the order is

src/lembas/db/models/persona.py

@@ -0,0 +1,96 @@
+"""Who a model is, and what it has made of the person it is talking to.
+
+Two different things, one table, and the discriminator is a column:
+
+* ``owner_id IS NULL`` -- the model's **persona**. Instance-wide, seeded by an
+  administrator, and rewritten by the model itself when it is allowed to.
+* ``owner_id`` set -- that model's **read of that person**, kept as it goes.
+  Per (model, person) rather than per model, because two models may honestly
+  arrive at different views of the same somebody, and on an instance with more
+  than one account nobody should inherit another person's reflection.
+
+Why not a fourth prompt layer: because *"system prompts replace, never stack"*
+is a decision this project has already taken. Both of these reach the model as
+``{{persona}}`` and ``{{person_view}}``, through ordinary fragments, exactly the
+way the memories block does.
+
+⚠ **``model_key`` is the model's text id, not the ``Model`` row's primary key**,
+and there is deliberately no foreign key to ``models``. "Test & refresh" on the
+connection screen deletes any model the endpoint no longer lists and recreates
+it when it comes back -- so a row keyed on the primary key would lose a model's
+whole personality to a refresh taken while its endpoint happened to be loading
+something else. This is the reasoning ``Chat.model_id`` already carries: the
+text id survives, and a row naming a model that no longer exists is invisible
+rather than broken.
+"""
+
+from __future__ import annotations
+
+from sqlalchemy import Boolean, ForeignKey, String, Text, UniqueConstraint
+from sqlalchemy.orm import Mapped, mapped_column, relationship
+
+from lembas.db.base import Base, Timestamps, UUIDPrimaryKey
+from lembas.db.models.library import AUTHOR_MODEL, AUTHOR_USER
+
+
+class Persona(UUIDPrimaryKey, Timestamps, Base):
+    """One model's personality, or one model's read of one person."""
+
+    __tablename__ = "personas"
+    __table_args__ = (UniqueConstraint("model_key", "owner_id"),)
+
+    # The model's `model_id`, not a `models.id`. See the module docstring.
+    model_key: Mapped[str] = mapped_column(String(300), nullable=False, index=True)
+
+    # NULL means "this is the model's own persona". Set means "this is what that
+    # model makes of this person".
+    owner_id: Mapped[str | None] = mapped_column(
+        String(32), ForeignKey("users.id", ondelete="CASCADE"), nullable=True, index=True
+    )
+
+    content: Mapped[str] = mapped_column(Text, default="")
+    # Who wrote what is in `content` now. A person reading their own reflection
+    # is entitled to know which of the two put each version there.
+    author: Mapped[str] = mapped_column(String(16), default=AUTHOR_MODEL, nullable=False)
+    # Switched off rather than deleted, so turning it off does not throw the text
+    # away and turning it back on does not need it retyped.
+    enabled: Mapped[bool] = mapped_column(Boolean, default=True, nullable=False)
+
+    revisions: Mapped[list[PersonaRevision]] = relationship(
+        back_populates="persona",
+        cascade="all, delete-orphan",
+        order_by="PersonaRevision.created_at.desc()",
+    )
+
+    @property
+    def is_reflection(self) -> bool:
+        return self.owner_id is not None
+
+    def __repr__(self) -> str:
+        kind = "reflection" if self.is_reflection else "persona"
+        return f"<Persona {kind} {self.model_key} {self.content[:30]!r}>"
+
+
+class PersonaRevision(UUIDPrimaryKey, Timestamps, Base):
+    """The state of a persona before a change.
+
+    The same safety story as `SkillRevision`, for the same reason and with the
+    same limit stated plainly: a model that has just read a hostile page can
+    rewrite its own personality, and what stops that being permanent is a record
+    and a way back rather than a gate.
+    """
+
+    __tablename__ = "persona_revisions"
+
+    persona_id: Mapped[str] = mapped_column(
+        String(32), ForeignKey("personas.id", ondelete="CASCADE"), nullable=False, index=True
+    )
+    content: Mapped[str] = mapped_column(Text, default="")
+    # Who made the change this revision is the "before" of.
+    author: Mapped[str] = mapped_column(String(16), default=AUTHOR_USER, nullable=False)
+    note: Mapped[str] = mapped_column(String(200), default="")
+
+    persona: Mapped[Persona] = relationship(back_populates="revisions")
+
+
+__all__ = ["AUTHOR_MODEL", "AUTHOR_USER", "Persona", "PersonaRevision"]