feat(rag): steering notes — tune how Brain answers, stored in Postgres and injected into every system prompt

app/api/steering.py

@@ -0,0 +1,74 @@
+"""Steering notes API — tune how Brain answers (phase 15, story
+``steering-notes``).
+
+Stateless CRUD under ``/api/steering`` (A10): notes are owner instructions
+stored in Postgres (``steering_notes``) and read into the system prompt of
+**every** chat turn as the ``<tuning>`` section (see
+:func:`app.rag.prompts.build_steering_section` and
+:func:`app.api.chat.chat`).
+"""
+from __future__ import annotations
+
+import uuid
+
+from fastapi import APIRouter, Depends, HTTPException, Response
+from sqlalchemy import select
+from sqlalchemy.orm import Session
+
+from app.db import get_db
+from app.models import SteeringNote
+from app.schemas import SteeringNote as SteeringNoteOut
+from app.schemas import SteeringNoteIn, SteeringNoteList
+
+router = APIRouter(prefix="/steering", tags=["steering"])
+
+
+def load_steering_notes(db: Session) -> list[str]:
+    """All steering notes, oldest first (the order they are numbered in the
+    ``<tuning>`` prompt section). Used by the chat turn (``app.api.chat``)."""
+    rows = db.scalars(
+        select(SteeringNote).order_by(SteeringNote.created_at.asc(), SteeringNote.id.asc())
+    ).all()
+    return [row.note for row in rows]
+
+
+@router.get("", response_model=SteeringNoteList)
+def list_steering_notes(
+    db: Session = Depends(get_db),  # noqa: B008
+) -> SteeringNoteList:
+    """All notes, newest first (the UI panel's display order)."""
+    rows = db.scalars(
+        select(SteeringNote).order_by(SteeringNote.created_at.desc(), SteeringNote.id.desc())
+    ).all()
+    return SteeringNoteList(
+        notes=[
+            SteeringNoteOut(id=row.id, note=row.note, created_at=row.created_at) for row in rows
+        ]
+    )
+
+
+@router.post("", response_model=SteeringNoteOut, status_code=201)
+def create_steering_note(
+    payload: SteeringNoteIn,
+    db: Session = Depends(get_db),  # noqa: B008
+) -> SteeringNoteOut:
+    """Store one tuning instruction (trimmed, 1–2000 chars — 422 otherwise)."""
+    row = SteeringNote(note=payload.note)
+    db.add(row)
+    db.commit()
+    db.refresh(row)
+    return SteeringNoteOut(id=row.id, note=row.note, created_at=row.created_at)
+
+
+@router.delete("/{note_id}", status_code=204)
+def delete_steering_note(
+    note_id: uuid.UUID,
+    db: Session = Depends(get_db),  # noqa: B008
+) -> Response:
+    """Remove a note; 404 when the id is unknown."""
+    row = db.get(SteeringNote, note_id)
+    if row is None:
+        raise HTTPException(status_code=404, detail="steering note not found")
+    db.delete(row)
+    db.commit()
+    return Response(status_code=204)