Complete Economic Observatory MVP (ADAPTIVE-WP-0002)

Add file-based Bubble, Stripe, and OpenRouter importers; usage attribution,
cost allocation, pricing simulator, credit wallets, and recommendations in the
dashboard API. Document whynot-design UI workflow and archive the finished
workplan with all ten tasks marked done.

projects/coulomb-pricing/observatory/credits.py

@@ -0,0 +1,48 @@
+from __future__ import annotations
+
+from decimal import Decimal, ROUND_HALF_UP
+from pathlib import Path
+from typing import Any
+
+from .load import _read_json, default_data_dir
+
+TWOPLACES = Decimal("0.01")
+
+
+def _money(value: Decimal) -> Decimal:
+    return value.quantize(TWOPLACES, rounding=ROUND_HALF_UP)
+
+
+def load_credit_wallets(data_dir=None) -> dict[str, Any]:
+    root = data_dir or default_data_dir()
+    path = Path(root) / "credit_wallets.json"
+    if not path.exists():
+        return {"version": 1, "currency": "EUR", "wallets": []}
+    return _read_json(path)
+
+
+def build_credit_summary(raw: dict, usage_by_member: dict[str, Decimal], period: str) -> dict:
+    wallets = []
+    for item in raw.get("wallets", []):
+        member_id = item["member_id"]
+        allowance = Decimal(str(item.get("monthly_allowance_eur", "0")))
+        used = usage_by_member.get(member_id, Decimal(str(item.get("used_eur", "0"))))
+        remaining = max(Decimal("0"), allowance - used)
+        wallets.append(
+            {
+                "member_id": member_id,
+                "period": period,
+                "monthly_allowance_eur": _money(allowance),
+                "used_eur": _money(used),
+                "remaining_eur": _money(remaining),
+                "overage_eur": _money(max(Decimal("0"), used - allowance)),
+            }
+        )
+
+    return {
+        "period": period,
+        "currency": raw.get("currency", "EUR"),
+        "wallet_count": len(wallets),
+        "wallets": wallets,
+        "notes": "Observatory-only credit accounting; no customer billing in MVP.",
+    }