refactor(server): extract the shop routes + inject get_progression_content into the seam (R3) (#851)

The progression-content substrate: `_get_progression_content` (a lazy,
double-checked-locking content cache) is now published into the appstate seam as
a CALLABLE. The cache global + lock + the function stay in server.py (startup
uses it, and test_progression_api patches `server._progression_content`
directly), so ZERO test retargeting — routers just call
`appstate.get_progression_content()`.

Because the accessor is defined at server.py:1152 but the import-top configure()
runs at :346, a second `appstate.configure(get_progression_content=...)` publishes
it right after the def (configure is idempotent/additive).

First consumer: routers/shop.py (3 routes: buy/equip/list). Bodies verbatim;
@app -> @router, meta_db -> appstate.meta_db, _clean_str from reqfields,
_get_progression_content() -> appstate.get_progression_content(). This unblocks
stats/progression/profile next (all share the accessor).

server.py: 7,880 -> 7,845.

Verified: pyflakes clean; route table IDENTICAL (143); pytest 2401 passed
(test_progression_api's server._progression_content patch still works via the
kept cache); packaging guard; eslint 0. Boot smoke: GET /api/shop 200 (drives
appstate.get_progression_content), buy 400 on bad body.

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/appstate.py

@@ -82,10 +82,16 @@ static_dir = None
 sloppak_cache_dir = None
 audio_cache_dir = None
 
+# Injected callables (not values): server owns the impl + its state, routers call
+# through the seam. get_progression_content wraps a lazy content cache that stays
+# in server.py (its `setattr(server, "_progression_content")` test is untouched).
+get_progression_content = None
+
 _SLOTS = frozenset({
     "meta_db", "audio_effect_mappings",
     "config_dir", "dlc_dir", "dlc_dir_env",
     "static_dir", "sloppak_cache_dir", "audio_cache_dir",
+    "get_progression_content",
 })
 
 

lib/routers/shop.py

@@ -0,0 +1,62 @@
+"""Cosmetics shop (spec 010) — buy/equip avatars & themes with earned currency.
+
+Extracted verbatim from ``server.py`` (R3); edits: ``@app`` -> ``@router``,
+``meta_db`` -> ``appstate.meta_db``, ``_get_progression_content()`` ->
+``appstate.get_progression_content()`` (the accessor is injected into the seam;
+its lazy content cache stays in server.py).
+"""
+
+from fastapi import APIRouter
+from fastapi.responses import JSONResponse
+
+import appstate
+from reqfields import _clean_str
+
+router = APIRouter()
+
+
+@router.get("/api/shop")
+def api_shop():
+    content = appstate.get_progression_content()
+    owned = appstate.meta_db.get_owned_items()
+    equipped = appstate.meta_db.get_equipped()
+    items = [
+        {**item, "owned": iid in owned, "equipped": equipped.get(item["slot"]) == iid}
+        for iid, item in sorted(content["shop"].items())
+    ]
+    return {"items": items, "wallet": appstate.meta_db.get_wallet()}
+
+
+@router.post("/api/shop/buy")
+def api_shop_buy(data: dict):
+    """Spend Decibels on a cosmetic. Atomic: balance check + spend + ownership
+    in one transaction. Decibels are earned by playing only — never purchasable."""
+    item_id = _clean_str(data.get("item_id"))
+    item = appstate.get_progression_content()["shop"].get(item_id)
+    if not item:
+        return JSONResponse({"error": f"unknown item: {item_id!r}"}, status_code=400)
+    status, wallet = appstate.meta_db.buy_shop_item(item)
+    if status == "owned":
+        return JSONResponse({"error": "already owned", "wallet": wallet}, status_code=409)
+    if status == "insufficient":
+        return JSONResponse({"error": "insufficient balance", "wallet": wallet}, status_code=402)
+    return {"ok": True, "item_id": item_id, "wallet": wallet}
+
+
+@router.post("/api/shop/equip")
+def api_shop_equip(data: dict):
+    """Equip an owned cosmetic into its slot. Body: {slot, item_id|null}
+    (null unequips, restoring the default look)."""
+    import progression as progression_mod
+    slot = _clean_str(data.get("slot"))
+    if slot not in progression_mod.SHOP_SLOTS:
+        return JSONResponse({"error": f"slot must be one of {sorted(progression_mod.SHOP_SLOTS)}"}, status_code=400)
+    item_id = data.get("item_id")
+    if item_id is not None:
+        item_id = _clean_str(item_id)
+        item = appstate.get_progression_content()["shop"].get(item_id)
+        if not item or item["slot"] != slot:
+            return JSONResponse({"error": f"unknown item for slot {slot}: {item_id!r}"}, status_code=400)
+        if item_id not in appstate.meta_db.get_owned_items():
+            return JSONResponse({"error": "item not owned"}, status_code=403)
+    return {"ok": True, "equipped": appstate.meta_db.equip_item(slot, item_id)}