Remove Google Sheets mirror entirely (#13)

Postgres is now the sole source of truth: delete sheets.py and
import_from_sheets.py, strip mirror_entity/mirror_async/_mirror_worker and
POST /api/sync from app.py, drop the tab/mirror keys from db.py's TABLES.
Re-point n8n/renewal-reminder.json at the CRM's own HTTP API (GET
/api/clients, POST /api/activity_log) instead of the Sheets nodes, and drop
SHEET_ID/GOOGLE_SA_JSON from deploy env/compose and requests from
requirements.txt (PyJWT stays — still used by booking_api.py). Updates
docs/README/playbooks accordingly and closes the old #5 (atomic mirror) as
moot.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backoffice/app/app.py

@@ -1,16 +1,12 @@
 """smb-crm back-office service.
 
-Postgres is the source of truth. This serves the operator dashboard + a small
-JSON API (read now; add/edit/delete and the DB->Sheets mirror layered on next).
+Postgres is the source of truth for the operator dashboard + a small JSON API.
 Browser access is gated by Caddy basic-auth on onboard.mivanchenko.de; the
 machine-to-machine ingest path (n8n) is gated by the CRM_API_TOKEN header.
 """
 import os
 import re
 import time
-import queue
-import threading
-import traceback
 from datetime import datetime, date, timezone
 from decimal import Decimal
 
@@ -20,7 +16,6 @@ from waitress import serve
 import booking_db as bdb
 import db
 import owner_mail
-from sheets import Sheets
 from booking_api import bp as booking_bp
 from public_booking import bp as public_booking_bp
 from manage_booking import bp as manage_booking_bp
@@ -47,69 +42,6 @@ CRM_TOKEN = os.environ.get("CRM_API_TOKEN", "")
 # the basic-auth header, so the feed is gated by this query token instead).
 ICS_TOKEN = os.environ.get("ICS_TOKEN", "")
 
-# DB -> Sheets one-way mirror. Postgres is the source of truth; the Sheet is a
-# best-effort projection. A mirror failure never fails the DB write.
-SH = None
-try:
-    SH = Sheets(os.environ["GOOGLE_SA_JSON"], os.environ["SHEET_ID"])
-except Exception:  # noqa: BLE001
-    traceback.print_exc()
-
-
-def _cell(v):
-    if v is None:
-        return ""
-    if isinstance(v, bool):
-        return "TRUE" if v else "FALSE"
-    if isinstance(v, datetime):
-        return v.strftime("%Y-%m-%d %H:%M")
-    if isinstance(v, date):
-        return v.strftime("%Y-%m-%d")
-    if isinstance(v, Decimal):
-        f = float(v)
-        return str(int(f)) if f == int(f) else str(f)
-    s = str(v)
-    return ("'" + s) if s[:1] in "=+-@" else s  # neutralise formula injection
-
-
-def mirror_entity(entity):
-    spec = db.TABLES[entity]
-    if SH is None or spec.get("mirror") is False:
-        return 0
-    cols = spec["cols"]
-    order = LIST_ORDER.get(entity, spec["pk"])
-    with db.connect() as conn, conn.cursor() as cur:
-        cur.execute(f"SELECT {', '.join(cols)} FROM {entity} ORDER BY {order}")
-        rows = cur.fetchall()
-    grid = [[_cell(r[c]) for c in cols] for r in rows]
-    SH.overwrite(spec["tab"], cols, grid)
-    return len(grid)
-
-
-# Serialize all mirror writes through one worker so concurrent mutations can't
-# race on the shared Sheets client / token.
-_mirror_q = queue.Queue()
-
-
-def _mirror_worker():
-    while True:
-        entity = _mirror_q.get()
-        try:
-            mirror_entity(entity)
-        except Exception:  # noqa: BLE001
-            print(f"[mirror] {entity} sync failed:", flush=True)
-            traceback.print_exc()
-        finally:
-            _mirror_q.task_done()
-
-
-threading.Thread(target=_mirror_worker, daemon=True).start()
-
-
-def mirror_async(entity):
-    if SH is not None and db.TABLES[entity].get("mirror") is not False:
-        _mirror_q.put(entity)
-
 # Static dashboard, with the CRM token injected so the (basic-auth-gated)
 # operator page can call the token-protected mutation endpoints.
 with open(os.path.join(os.path.dirname(__file__), "static", "index.html")) as _f:
@@ -235,8 +167,6 @@ def add_entity(entity):
                     [row.get(c) for c in cols])
         log_activity(cur, row.get("client_id"), f"add {entity}", f"{pk}={row.get(pk)}")
         conn.commit()
-    mirror_async(entity)
-    mirror_async("activity_log")
     return jsonify({"added": row.get(pk)}), 201
 
 
@@ -262,8 +192,6 @@ def edit_entity(entity, ident):
         log_activity(cur, ident if entity == "clients" else None,
                      f"edit {entity}", f"{pk}={ident}: {', '.join(setcols)}")
         conn.commit()
-    mirror_async(entity)
-    mirror_async("activity_log")
     return jsonify({"updated": ident, "fields": setcols})
 
 
@@ -281,8 +209,6 @@ def delete_entity(entity, ident):
         log_activity(cur, ident if entity == "clients" else None,
                      f"delete {entity}", f"{pk}={ident}")
         conn.commit()
-    mirror_async(entity)
-    mirror_async("activity_log")
     return jsonify({"deleted": ident})
 
 
@@ -313,26 +239,9 @@ def trigger_owner_password_reset(user_id):
         log_activity(cur, user["client_id"], "owner password reset",
                      f"user_id={user_id} (operator-triggered)")
         conn.commit()
-    mirror_async("activity_log")
     return jsonify({"sent": user_id})
 
 
-@app.post("/api/sync")
-def sync_all():
-    """Full DB -> Sheets resync of every tab (manual / alignment)."""
-    if not authed():
-        return jsonify({"error": "forbidden"}), 403
-    if SH is None:
-        return jsonify({"error": "sheets unavailable"}), 503
-    out = {}
-    for entity in db.TABLES:
-        try:
-            out[entity] = mirror_entity(entity)
-        except Exception as e:  # noqa: BLE001
-            out[entity] = f"error: {e}"
-    return jsonify({"synced": out})
-
-
 def _ics_dt(v):
     if isinstance(v, datetime):
         u = v if v.tzinfo else v.replace(tzinfo=timezone.utc)