fix(settings): ceo_name write-through renames the CEO agent row

The ceo_name setting only reached the panel header — the CEO agent row
kept its seeded name, so agent selectors (create-flag, assignee pickers,
kanban) still showed the old name after a rename. Setting ceo_name now
updates the CEO row's name in the same transaction, resolved via the
shared duplicate-tolerant get_agent_by_role lookup. The seed path never
overwrites existing rows, so a custom name survives restarts. The
agent-facing docs/map entries drop the personal name. Write-through
tests pin ancient created_at on fixture rows so they stay deterministic
against CEO rows other suite tests may have committed.

tests/unit/services/test_settings_service.py

@@ -2,9 +2,12 @@
 
 from __future__ import annotations
 
+from datetime import UTC, datetime
 from typing import Any
+from uuid import uuid4
 
 import pytest
+from roboco.db.tables import AgentRole, AgentStatus, AgentTable
 from roboco.services.settings import (
     SettingValidationError,
     get_settings_service,
@@ -12,6 +15,29 @@ from roboco.services.settings import (
 )
 
 
+def _ceo_agent(name: str = "Renzo", created_at: datetime | None = None) -> AgentTable:
+    """A minimal CEO-role agent row for write-through tests.
+
+    `created_at` defaults to an ancient timestamp so this row is the
+    earliest-created CEO regardless of rows other suite tests may have
+    committed into the shared DB — the write-through targets the oldest.
+    """
+    return AgentTable(
+        id=uuid4(),
+        name=name,
+        slug=f"ceo-{uuid4().hex[:6]}",
+        role=AgentRole.CEO,
+        team=None,
+        status=AgentStatus.ACTIVE,
+        model_config={},
+        system_prompt="x",
+        capabilities=[],
+        permissions={},
+        metrics={},
+        created_at=created_at or datetime(2000, 1, 1, tzinfo=UTC),
+    )
+
+
 def test_validate_setting_rejects_unknown_key() -> None:
     with pytest.raises(SettingValidationError):
         validate_setting("not_a_real_setting", "x")
@@ -77,3 +103,57 @@ async def test_ceo_name_set_rejects_blank_value(db_session: Any) -> None:
     svc = get_settings_service(db_session)
     with pytest.raises(SettingValidationError):
         await svc.set("ceo_name", "   ")
+
+
+@pytest.mark.asyncio
+async def test_ceo_name_set_writes_through_to_ceo_agent_row(db_session: Any) -> None:
+    agent = _ceo_agent()
+    db_session.add(agent)
+    await db_session.flush()
+
+    svc = get_settings_service(db_session)
+    await svc.set("ceo_name", "Alice")
+
+    await db_session.refresh(agent)
+    assert agent.name == "Alice"
+
+
+@pytest.mark.asyncio
+async def test_ceo_name_set_strips_whitespace_on_agent_row(db_session: Any) -> None:
+    agent = _ceo_agent()
+    db_session.add(agent)
+    await db_session.flush()
+
+    svc = get_settings_service(db_session)
+    await svc.set("ceo_name", "  Bob  ")
+
+    await db_session.refresh(agent)
+    assert agent.name == "Bob"
+
+
+@pytest.mark.asyncio
+async def test_ceo_name_set_with_no_ceo_agent_does_not_raise(
+    db_session: Any,
+) -> None:
+    svc = get_settings_service(db_session)
+    await svc.set("ceo_name", "Alice")  # no CEO row seeded — no-op, no crash
+    assert await svc.get("ceo_name") == "Alice"
+
+
+@pytest.mark.asyncio
+async def test_ceo_name_set_tolerates_duplicate_ceo_rows(db_session: Any) -> None:
+    """A second role=CEO row must not crash the write-through (no bare one_or_none)."""
+    older = _ceo_agent("Renzo", created_at=datetime(2000, 1, 1, tzinfo=UTC))
+    db_session.add(older)
+    await db_session.flush()
+    newer = _ceo_agent("Renzo", created_at=datetime(2000, 1, 2, tzinfo=UTC))
+    db_session.add(newer)
+    await db_session.flush()
+
+    svc = get_settings_service(db_session)
+    await svc.set("ceo_name", "Alice")  # must not raise MultipleResultsFound
+
+    await db_session.refresh(older)
+    await db_session.refresh(newer)
+    assert older.name == "Alice"  # earliest-created wins
+    assert newer.name == "Renzo"  # the duplicate is left untouched