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

app/schemas.py

@@ -1,7 +1,10 @@
 """Pydantic request/response schemas (API contract)."""
 from __future__ import annotations
 
-from pydantic import BaseModel, Field
+import uuid
+from datetime import datetime
+
+from pydantic import BaseModel, Field, field_validator
 
 
 class HealthResponse(BaseModel):
@@ -73,3 +76,33 @@ class DocContent(BaseModel):
     content: str
     indexed_at: str
     chunks: int
+
+
+class SteeringNoteIn(BaseModel):
+    """``POST /api/steering`` body: one tuning instruction (phase 15).
+
+    The note is trimmed *before* the length constraints run, so a
+    whitespace-only body is a 422 and a 2000-char note with surrounding
+    spaces still passes.
+    """
+
+    note: str = Field(min_length=1, max_length=2000)
+
+    @field_validator("note", mode="before")
+    @classmethod
+    def _trim_note(cls, v: object) -> object:
+        return v.strip() if isinstance(v, str) else v
+
+
+class SteeringNote(BaseModel):
+    """One stored steering note (API shape — ISO-8601 ``created_at``)."""
+
+    id: uuid.UUID
+    note: str
+    created_at: datetime
+
+
+class SteeringNoteList(BaseModel):
+    """``GET /api/steering`` response: all notes, newest first."""
+
+    notes: list[SteeringNote]