ai-agent-book 精选快照（<2MB 代码与文档，来自 github.com/bojieli/ai-agent-book）

chapter7/model-action-threshold/tasks/cache_contract/repo/cachelib/__init__.py

@@ -0,0 +1,3 @@
+from cachelib.cache import Cache
+
+__all__ = ["Cache"]

chapter7/model-action-threshold/tasks/cache_contract/repo/cachelib/cache.py

@@ -0,0 +1,17 @@
+class Cache:
+    def __init__(self):
+        self._values = {}
+
+    def get(self, key, default=None):
+        return self._values.get(key, default)
+
+    def put(self, key, value):
+        self._values[key] = value
+
+    def get_or_load(self, key, loader):
+        cached = self.get(key)
+        if cached is not None:
+            return cached
+        value = loader(key)
+        self.put(key, value)
+        return value

chapter7/model-action-threshold/tasks/cache_contract/repo/cachelib/catalog.py

@@ -0,0 +1,7 @@
+class Catalog:
+    def __init__(self, cache, fetch_product):
+        self.cache = cache
+        self.fetch_product = fetch_product
+
+    def product(self, product_id):
+        return self.cache.get_or_load(product_id, self.fetch_product)

chapter7/model-action-threshold/tasks/cache_contract/repo/tests/test_cache.py

@@ -0,0 +1,40 @@
+import unittest
+
+from cachelib import Cache
+
+
+class CacheContractTests(unittest.TestCase):
+    def test_negative_lookup_is_loaded_once(self):
+        cache = Cache()
+        calls = []
+
+        def loader(key):
+            calls.append(key)
+            return None
+
+        self.assertIsNone(cache.get_or_load("missing", loader))
+        self.assertIsNone(cache.get_or_load("missing", loader))
+        self.assertEqual(calls, ["missing"])
+
+    def test_custom_default_still_distinguishes_missing_from_none(self):
+        cache = Cache()
+        marker = object()
+        self.assertIs(cache.get("unknown", marker), marker)
+        cache.put("known-none", None)
+        self.assertIsNone(cache.get("known-none", marker))
+
+    def test_falsey_values_are_cached(self):
+        cache = Cache()
+        calls = []
+
+        def loader(key):
+            calls.append(key)
+            return 0
+
+        self.assertEqual(cache.get_or_load("zero", loader), 0)
+        self.assertEqual(cache.get_or_load("zero", loader), 0)
+        self.assertEqual(calls, ["zero"])
+
+
+if __name__ == "__main__":
+    unittest.main()

chapter7/model-action-threshold/tasks/cache_contract/task.json

@@ -0,0 +1,5 @@
+{
+  "category": "contract-sensitive",
+  "instruction": "Fix the cache so that negative lookups (a loader returning None) are cached instead of reloaded on every call. Preserve the public get(key, default=None), put, and get_or_load APIs, including the ability to distinguish a missing key when a caller supplies a custom default.",
+  "test_command": ["python", "-m", "unittest", "discover", "-s", "tests", "-v"]
+}