diff --git a/backend/tests/conftest.py b/backend/tests/conftest.py
new file mode 100644
index 0000000..b63f213
--- /dev/null
+++ b/backend/tests/conftest.py
@@ -0,0 +1,57 @@
+"""Shared setup for the test suite.
+
+pytest imports this file before it imports any test module, which is the only
+reason the database redirection below works. `app.database` reads
+`AIDND_DB_PATH` at import and builds `engine` from it once, so the variable has
+to be set before the first `from app...` line anywhere in the suite.
+
+Every test module used to carry its own copy of that redirection. Only the first
+one to be imported ever took effect, because the engine already existed by the
+time the second one ran. The other copies created a temp file that nothing
+opened and nothing deleted. One copy here does the job, and it cleans up after
+itself.
+
+The tests share one database. That is not new: they already did. Each `client`
+fixture calls `Base.metadata.create_all` on setup and `drop_all` on teardown, so
+no test sees another test's rows.
+"""
+import os
+import tempfile
+
+_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
+_tmp.close()
+os.environ["AIDND_DB_PATH"] = _tmp.name
+# A real `AIDND_DATABASE_URL` or `DATABASE_URL` in the developer's shell points
+# at Postgres, and `app.database` prefers either over the SQLite path above.
+# Clear both, so running the suite never touches a server database.
+os.environ.pop("AIDND_DATABASE_URL", None)
+os.environ.pop("DATABASE_URL", None)
+
+import pytest  # noqa: E402  Import order is load-bearing; see above.
+
+from fakes import ScriptedProvider  # noqa: E402
+
+
+@pytest.fixture(autouse=True)
+def reset_scripted_provider():
+    """Clears the fake provider's state between tests.
+
+    `ScriptedProvider` keeps its replies and its call count on the class, because
+    the code under test constructs the provider itself and a test cannot reach
+    the instance. Class state outlives a test, so reset it here rather than
+    trusting every fixture to remember.
+    """
+    ScriptedProvider.replies = []
+    ScriptedProvider.calls = 0
+    ScriptedProvider.prompts = []
+    yield
+
+
+def pytest_sessionfinish(session, exitstatus):
+    """Deletes the temporary database once the run ends."""
+    try:
+        os.unlink(_tmp.name)
+    except OSError:
+        # The file is already gone, or Windows still holds a handle on it. It is
+        # in the temp directory either way, so leaving it costs nothing.
+        pass
diff --git a/backend/tests/fakes.py b/backend/tests/fakes.py
new file mode 100644
index 0000000..8b035c9
--- /dev/null
+++ b/backend/tests/fakes.py
@@ -0,0 +1,41 @@
+"""Stand-ins for the parts of the app a test must not really call.
+
+Import these rather than writing another copy. Nine test modules each carried
+their own `ScriptedProvider`, and the copies had drifted into four different
+feature sets, so a test that needed to raise a provider error had to be written
+in one of the files whose copy supported it.
+"""
+
+
+class ScriptedProvider:
+    """Streams canned replies in place of `OpenAICompatibleProvider`.
+
+    Set `replies` to the texts the model returns, one per call. The last entry
+    repeats once the list runs out, so a test that plays more turns than it
+    scripted still gets text. To drive the provider-error path, put an
+    `Exception` in the list. It is raised rather than streamed.
+
+    State lives on the class, not on the instance, because the turn engine
+    constructs the provider itself and a test never sees the object. The autouse
+    `reset_scripted_provider` fixture in `conftest.py` clears it between tests.
+
+    `prompts` records every assembled `(system, story)` pair, which is what a
+    test asserts on to check what the model was shown.
+    """
+
+    last_usage = None
+    replies: list = []
+    calls = 0
+    prompts: list = []
+
+    def __init__(self, *a, **k):
+        pass
+
+    async def generate(self, parts, *, temperature, max_tokens):
+        index = min(ScriptedProvider.calls, len(ScriptedProvider.replies) - 1)
+        ScriptedProvider.calls += 1
+        ScriptedProvider.prompts.append((parts.system, parts.story))
+        reply = ScriptedProvider.replies[index]
+        if isinstance(reply, Exception):
+            raise reply
+        yield ("text", reply)
diff --git a/backend/tests/test_accesslog.py b/backend/tests/test_accesslog.py
index d014974..5a1da0c 100644
--- a/backend/tests/test_accesslog.py
+++ b/backend/tests/test_accesslog.py
@@ -9,15 +9,6 @@ accounts on a schedule, and a log that deletes itself is not a log.
 
     python -m pytest tests/test_accesslog.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
diff --git a/backend/tests/test_action_paging.py b/backend/tests/test_action_paging.py
index 6f4280a..4c09d7c 100644
--- a/backend/tests/test_action_paging.py
+++ b/backend/tests/test_action_paging.py
@@ -12,15 +12,6 @@ to be scrolling. An anchor means the same thing before and after.
 
     python -m pytest tests/test_action_paging.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
diff --git a/backend/tests/test_analytics.py b/backend/tests/test_analytics.py
index e8765c4..f0e3eb4 100644
--- a/backend/tests/test_analytics.py
+++ b/backend/tests/test_analytics.py
@@ -9,15 +9,6 @@ the dashboard, and cannot inflate what it reports beyond hitting the page.
 
     python -m pytest tests/test_analytics.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 from datetime import timedelta
 
 import pytest
diff --git a/backend/tests/test_attempt_siblings.py b/backend/tests/test_attempt_siblings.py
index dbe0252..2afbbb8 100644
--- a/backend/tests/test_attempt_siblings.py
+++ b/backend/tests/test_attempt_siblings.py
@@ -8,15 +8,6 @@ story, and the arrangement costs neither an extra prompt nor an extra turn.
 
     python -m pytest tests/test_attempt_siblings.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
@@ -26,9 +17,10 @@ from app import attempts, auth, limits, models, tree
 from app.context import cursors, history
 from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
-from app.providers import PromptParts
 from app.routers import adventures
 
+from fakes import ScriptedProvider
+
 SCHEMA = {"player": {"hp": {"min": 0, "max": 100, "initial": 100}}}
 
 GOLD_SCRIPT = """
@@ -40,22 +32,6 @@ modifier(text);
 """
 
 
-class ScriptedProvider:
-    last_usage = None
-    replies: list = []
-    calls = 0
-    prompts: list = []
-
-    def __init__(self, *a, **k):
-        pass
-
-    async def generate(self, parts: PromptParts, *, temperature, max_tokens):
-        index = min(ScriptedProvider.calls, len(ScriptedProvider.replies) - 1)
-        ScriptedProvider.calls += 1
-        ScriptedProvider.prompts.append((parts.system, parts.story))
-        yield ("text", ScriptedProvider.replies[index])
-
-
 @pytest.fixture()
 def client(monkeypatch):
     Base.metadata.create_all(bind=engine)
diff --git a/backend/tests/test_branch_clause.py b/backend/tests/test_branch_clause.py
index cf84fdf..6e52fd5 100644
--- a/backend/tests/test_branch_clause.py
+++ b/backend/tests/test_branch_clause.py
@@ -21,15 +21,6 @@ nodes may appear on C.
 
     python -m pytest tests/test_branch_clause.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
diff --git a/backend/tests/test_branch_forking.py b/backend/tests/test_branch_forking.py
index 41cac9b..9fb1181 100644
--- a/backend/tests/test_branch_forking.py
+++ b/backend/tests/test_branch_forking.py
@@ -12,15 +12,6 @@ that makes borrowing possible lives in `lineage`.
 
     python -m pytest tests/test_branch_forking.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
@@ -29,9 +20,10 @@ from app import auth, limits, models
 from app.context import cursors, lineage
 from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
-from app.providers import PromptParts
 from app.routers import adventures
 
+from fakes import ScriptedProvider
+
 # `hp` moves freely. `mana` has a cooldown of 2 turns, so an incorrect
 # advance shows up as a change the referee should have rejected.
 SCHEMA = {
@@ -50,22 +42,6 @@ modifier(text);
 """
 
 
-class ScriptedProvider:
-    last_usage = None
-    replies: list = []
-    calls = 0
-    prompts: list = []
-
-    def __init__(self, *a, **k):
-        pass
-
-    async def generate(self, parts: PromptParts, *, temperature, max_tokens):
-        index = min(ScriptedProvider.calls, len(ScriptedProvider.replies) - 1)
-        ScriptedProvider.calls += 1
-        ScriptedProvider.prompts.append((parts.system, parts.story))
-        yield ("text", ScriptedProvider.replies[index])
-
-
 @pytest.fixture()
 def client(monkeypatch):
     Base.metadata.create_all(bind=engine)
diff --git a/backend/tests/test_branch_management.py b/backend/tests/test_branch_management.py
index 27023ea..5c1f0b0 100644
--- a/backend/tests/test_branch_management.py
+++ b/backend/tests/test_branch_management.py
@@ -19,15 +19,6 @@ Two rules carry most of this file:
 
     python -m pytest tests/test_branch_management.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
@@ -37,22 +28,9 @@ from app import auth, limits, models, schemas
 from app.context import cursors, lineage
 from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
-from app.providers import PromptParts
 from app.routers import adventures
 
-
-class ScriptedProvider:
-    last_usage = None
-    replies: list = []
-    calls = 0
-
-    def __init__(self, *a, **k):
-        pass
-
-    async def generate(self, parts: PromptParts, *, temperature, max_tokens):
-        index = min(ScriptedProvider.calls, len(ScriptedProvider.replies) - 1)
-        ScriptedProvider.calls += 1
-        yield ("text", ScriptedProvider.replies[index])
+from fakes import ScriptedProvider
 
 
 @pytest.fixture()
diff --git a/backend/tests/test_bundle_v2.py b/backend/tests/test_bundle_v2.py
index cb2ff28..e3c0682 100644
--- a/backend/tests/test_bundle_v2.py
+++ b/backend/tests/test_bundle_v2.py
@@ -23,15 +23,6 @@ importer a file that does disagree with itself.
 
     python -m pytest tests/test_bundle_v2.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
@@ -40,9 +31,10 @@ from app import auth, bundle, limits, models
 from app.context import lineage
 from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
-from app.providers import PromptParts
 from app.routers import adventures
 
+from fakes import ScriptedProvider
+
 SCHEMA = {"player": {"hp": {"min": 0, "max": 100, "initial": 100}}}
 
 # Ten gold a turn, so the stored gold total tells how many turns the
@@ -58,20 +50,6 @@ modifier(text);
 OPENING = "You enter a cave."
 
 
-class ScriptedProvider:
-    last_usage = None
-    replies: list = []
-    calls = 0
-
-    def __init__(self, *a, **k):
-        pass
-
-    async def generate(self, parts: PromptParts, *, temperature, max_tokens):
-        index = min(ScriptedProvider.calls, len(ScriptedProvider.replies) - 1)
-        ScriptedProvider.calls += 1
-        yield ("text", ScriptedProvider.replies[index])
-
-
 @pytest.fixture()
 def client(monkeypatch):
     Base.metadata.create_all(bind=engine)
diff --git a/backend/tests/test_chat.py b/backend/tests/test_chat.py
index df52166..42acfce 100644
--- a/backend/tests/test_chat.py
+++ b/backend/tests/test_chat.py
@@ -6,15 +6,6 @@ page.
 
     python -m pytest tests/test_chat.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
diff --git a/backend/tests/test_egress.py b/backend/tests/test_egress.py
index 64cf5b5..372f72e 100644
--- a/backend/tests/test_egress.py
+++ b/backend/tests/test_egress.py
@@ -17,15 +17,6 @@ Two kinds of guard live here, and both are needed:
 
     python -m pytest tests/test_egress.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import json
 import random
 
diff --git a/backend/tests/test_embedding_blob.py b/backend/tests/test_embedding_blob.py
index c45a2c0..6fa82a5 100644
--- a/backend/tests/test_embedding_blob.py
+++ b/backend/tests/test_embedding_blob.py
@@ -7,15 +7,8 @@ for bit, and that the migration reaches every row, however many there are.
 
     python -m pytest tests/test_embedding_blob.py -v
 """
-import os
 import struct
-import tempfile
 
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
 
 import json
 import random
diff --git a/backend/tests/test_embedding_model_switch.py b/backend/tests/test_embedding_model_switch.py
index 4e3db33..292d62d 100644
--- a/backend/tests/test_embedding_model_switch.py
+++ b/backend/tests/test_embedding_model_switch.py
@@ -19,15 +19,6 @@ garbage instead.
 
     python -m pytest tests/test_embedding_model_switch.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import asyncio
 
 import pytest
diff --git a/backend/tests/test_guest_cleanup.py b/backend/tests/test_guest_cleanup.py
index 995ba57..5f180d4 100644
--- a/backend/tests/test_guest_cleanup.py
+++ b/backend/tests/test_guest_cleanup.py
@@ -6,15 +6,8 @@ deleted.
 
     python -m pytest tests/test_guest_cleanup.py -v
 """
-import os
-import tempfile
 from datetime import timedelta
 
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
 
 import pytest
 from sqlalchemy import create_engine, event
diff --git a/backend/tests/test_history_window.py b/backend/tests/test_history_window.py
index d0a5635..54972c0 100644
--- a/backend/tests/test_history_window.py
+++ b/backend/tests/test_history_window.py
@@ -16,15 +16,6 @@ Two things must hold, and both are easy to break by accident:
 
     python -m pytest tests/test_history_window.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from sqlalchemy import event
 
diff --git a/backend/tests/test_length_hint.py b/backend/tests/test_length_hint.py
index 7477e29..0c26659 100644
--- a/backend/tests/test_length_hint.py
+++ b/backend/tests/test_length_hint.py
@@ -16,15 +16,8 @@ Two things are easy to break here:
 
     python -m pytest tests/test_length_hint.py -v
 """
-import os
 import re
-import tempfile
 
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
 
 import pytest
 
diff --git a/backend/tests/test_memory_nodes.py b/backend/tests/test_memory_nodes.py
index e2fa158..2d6f24f 100644
--- a/backend/tests/test_memory_nodes.py
+++ b/backend/tests/test_memory_nodes.py
@@ -19,15 +19,6 @@ exactly as `test_branch_clause.py` builds it.
 
     python -m pytest tests/test_memory_nodes.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import asyncio
 
 import pytest
diff --git a/backend/tests/test_memory_retrieval.py b/backend/tests/test_memory_retrieval.py
index 110902d..98980f2 100644
--- a/backend/tests/test_memory_retrieval.py
+++ b/backend/tests/test_memory_retrieval.py
@@ -14,15 +14,6 @@ failure that no error message would report:
 
     python -m pytest tests/test_memory_retrieval.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import asyncio
 from datetime import timedelta
 
diff --git a/backend/tests/test_memory_settling.py b/backend/tests/test_memory_settling.py
index fa0fdb8..f339b7e 100644
--- a/backend/tests/test_memory_settling.py
+++ b/backend/tests/test_memory_settling.py
@@ -23,14 +23,7 @@ happened.
     python -m pytest tests/test_memory_settling.py -v
 """
 import asyncio
-import os
-import tempfile
 
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
 
 import pytest
 
diff --git a/backend/tests/test_netguard.py b/backend/tests/test_netguard.py
index a0465f4..4b4e962 100644
--- a/backend/tests/test_netguard.py
+++ b/backend/tests/test_netguard.py
@@ -2,15 +2,6 @@
 
     python -m pytest tests/test_netguard.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 
 from app import auth, netguard
diff --git a/backend/tests/test_prompt_caching.py b/backend/tests/test_prompt_caching.py
index a84c0dd..88d51af 100644
--- a/backend/tests/test_prompt_caching.py
+++ b/backend/tests/test_prompt_caching.py
@@ -25,13 +25,7 @@ than assumed.
     python -m pytest tests/test_prompt_caching.py -v
 """
 import os
-import tempfile
 
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
 
 import pytest
 
diff --git a/backend/tests/test_ratelimit_hardening.py b/backend/tests/test_ratelimit_hardening.py
index 60328e0..a83455f 100644
--- a/backend/tests/test_ratelimit_hardening.py
+++ b/backend/tests/test_ratelimit_hardening.py
@@ -9,15 +9,6 @@ also has an email-keyed throttle that no IP trick can weaken.
 
     python -m pytest tests/test_ratelimit_hardening.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 
 from app import auth, limits
diff --git a/backend/tests/test_retry_variants.py b/backend/tests/test_retry_variants.py
index 4623bbf..fad75c6 100644
--- a/backend/tests/test_retry_variants.py
+++ b/backend/tests/test_retry_variants.py
@@ -4,15 +4,6 @@ switchable, restoring the world/script state that attempt produced.
 
     python -m pytest tests/test_retry_variants.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
@@ -20,9 +11,11 @@ from fastapi.testclient import TestClient
 from app import auth, limits, models
 from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
-from app.providers import PromptParts, ProviderError
+from app.providers import ProviderError
 from app.routers import adventures
 
+from fakes import ScriptedProvider
+
 SCHEMA = {"player": {"hp": {"min": 0, "max": 100, "initial": 100}}}
 
 # Each turn spends 10 gold, so a double-applied or un-rolled-back attempt shows.
@@ -35,26 +28,6 @@ modifier(text);
 """
 
 
-class ScriptedProvider:
-    """Streams the next canned reply each call, so successive retries differ."""
-    last_usage = None
-    replies: list = []
-    calls = 0
-    prompts: list = []  # every assembled (system, story) pair, for context assertions
-
-    def __init__(self, *a, **k):
-        pass
-
-    async def generate(self, parts: PromptParts, *, temperature, max_tokens):
-        index = min(ScriptedProvider.calls, len(ScriptedProvider.replies) - 1)
-        ScriptedProvider.calls += 1
-        ScriptedProvider.prompts.append((parts.system, parts.story))
-        reply = ScriptedProvider.replies[index]
-        if isinstance(reply, Exception):
-            raise reply
-        yield ("text", reply)
-
-
 @pytest.fixture()
 def client(monkeypatch):
     Base.metadata.create_all(bind=engine)
diff --git a/backend/tests/test_scenario_art.py b/backend/tests/test_scenario_art.py
index 44d8180..3d7e46c 100644
--- a/backend/tests/test_scenario_art.py
+++ b/backend/tests/test_scenario_art.py
@@ -9,14 +9,7 @@ player's last line.
     python -m pytest tests/test_scenario_art.py -v
 """
 import base64
-import os
-import tempfile
 
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
 
 import pytest
 from fastapi import Depends
diff --git a/backend/tests/test_scenario_refresh.py b/backend/tests/test_scenario_refresh.py
index d5c0d73..9e37532 100644
--- a/backend/tests/test_scenario_refresh.py
+++ b/backend/tests/test_scenario_refresh.py
@@ -3,15 +3,6 @@ story cards and stat schema back down over a running adventure's copy.
 
     python -m pytest tests/test_scenario_refresh.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
diff --git a/backend/tests/test_seed_sweep.py b/backend/tests/test_seed_sweep.py
index c5affd0..0ff965d 100644
--- a/backend/tests/test_seed_sweep.py
+++ b/backend/tests/test_seed_sweep.py
@@ -8,14 +8,7 @@ deletes seeded rows no file claims any more.
     python -m pytest tests/test_seed_sweep.py -v
 """
 import json
-import os
-import tempfile
 
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
 
 import pytest
 
diff --git a/backend/tests/test_snapshot_compression.py b/backend/tests/test_snapshot_compression.py
index 20e9fd9..26b8e23 100644
--- a/backend/tests/test_snapshot_compression.py
+++ b/backend/tests/test_snapshot_compression.py
@@ -17,16 +17,9 @@ Three things must hold, and only the first is obvious:
     python -m pytest tests/test_snapshot_compression.py -v
 """
 import json
-import os
 import random
-import tempfile
 import zlib
 
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
 
 import pytest
 from sqlalchemy import text
diff --git a/backend/tests/test_starter_adventure.py b/backend/tests/test_starter_adventure.py
index 38e478a..3ca393e 100644
--- a/backend/tests/test_starter_adventure.py
+++ b/backend/tests/test_starter_adventure.py
@@ -8,14 +8,7 @@ empty account would.
     python -m pytest tests/test_starter_adventure.py -v
 """
 import json
-import os
-import tempfile
 
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
 
 import pytest
 from sqlalchemy import create_engine, event
diff --git a/backend/tests/test_state_revert.py b/backend/tests/test_state_revert.py
index 9fe18aa..998241b 100644
--- a/backend/tests/test_state_revert.py
+++ b/backend/tests/test_state_revert.py
@@ -11,17 +11,10 @@ only in their outcome.
 
 Run from the backend dir:  python -m pytest tests/test_state_revert.py -v
 """
-import os
-import tempfile
 
 # Point the app at a throwaway SQLite file before importing anything that
 # binds the engine at import time. `app.database` reads `AIDND_DB_PATH`
 # on import.
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
 
 import pytest
 from fastapi import HTTPException
diff --git a/backend/tests/test_story_tree_baseline.py b/backend/tests/test_story_tree_baseline.py
index 36b7697..f5cf8b5 100644
--- a/backend/tests/test_story_tree_baseline.py
+++ b/backend/tests/test_story_tree_baseline.py
@@ -17,15 +17,6 @@ those subphases, the change is wrong, not the test. SP4 is the first
 subphase allowed to move it, and only for the variant-count semantics
 called out in plan/14.
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
@@ -33,9 +24,10 @@ from fastapi.testclient import TestClient
 from app import auth, limits, models
 from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
-from app.providers import PromptParts
 from app.routers import adventures
 
+from fakes import ScriptedProvider
+
 # A world-state schema, so the RPG layer is exercised rather than skipped.
 SCHEMA = {"player": {"hp": {"min": 0, "max": 100, "initial": 100}}}
 
@@ -52,27 +44,6 @@ modifier(text);
 OPENING = "You enter a cave."
 
 
-class ScriptedProvider:
-    """Streams the next canned reply each call, so successive turns differ."""
-    last_usage = None
-
-    replies: list = []
-    calls = 0
-    prompts: list = []  # every assembled (system, story) pair
-
-    def __init__(self, *a, **k):
-        pass
-
-    async def generate(self, parts: PromptParts, *, temperature, max_tokens):
-        index = min(ScriptedProvider.calls, len(ScriptedProvider.replies) - 1)
-        ScriptedProvider.calls += 1
-        ScriptedProvider.prompts.append((parts.system, parts.story))
-        reply = ScriptedProvider.replies[index]
-        if isinstance(reply, Exception):
-            raise reply
-        yield ("text", reply)
-
-
 def _make_world(monkeypatch, *, seeded_actions: int = 0):
     """Create a user, a scenario, and an adventure, with `seeded_actions`
     extra story actions written straight to the database. Paging tests need
diff --git a/backend/tests/test_take_edit.py b/backend/tests/test_take_edit.py
index 5300490..d02c433 100644
--- a/backend/tests/test_take_edit.py
+++ b/backend/tests/test_take_edit.py
@@ -20,15 +20,6 @@ be silently broken.
 
     python -m pytest tests/test_take_edit.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
@@ -36,22 +27,9 @@ from fastapi.testclient import TestClient
 from app import auth, limits, models
 from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
-from app.providers import PromptParts
 from app.routers import adventures
 
-
-class ScriptedProvider:
-    last_usage = None
-    replies: list = []
-    calls = 0
-
-    def __init__(self, *a, **k):
-        pass
-
-    async def generate(self, parts: PromptParts, *, temperature, max_tokens):
-        index = min(ScriptedProvider.calls, len(ScriptedProvider.replies) - 1)
-        ScriptedProvider.calls += 1
-        yield ("text", ScriptedProvider.replies[index])
+from fakes import ScriptedProvider
 
 
 @pytest.fixture()
diff --git a/backend/tests/test_take_parentage.py b/backend/tests/test_take_parentage.py
index 47fbe84..0ce72e0 100644
--- a/backend/tests/test_take_parentage.py
+++ b/backend/tests/test_take_parentage.py
@@ -20,14 +20,7 @@ they mean.
     python -m pytest tests/test_take_parentage.py -v
 """
 import json
-import os
-import tempfile
 
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
 
 import pytest
 from fastapi import Depends
@@ -36,22 +29,9 @@ from fastapi.testclient import TestClient
 from app import attempts, auth, limits, models
 from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
-from app.providers import PromptParts
 from app.routers import adventures
 
-
-class ScriptedProvider:
-    last_usage = None
-    replies: list = []
-    calls = 0
-
-    def __init__(self, *a, **k):
-        pass
-
-    async def generate(self, parts: PromptParts, *, temperature, max_tokens):
-        index = min(ScriptedProvider.calls, len(ScriptedProvider.replies) - 1)
-        ScriptedProvider.calls += 1
-        yield ("text", ScriptedProvider.replies[index])
+from fakes import ScriptedProvider
 
 
 @pytest.fixture()
diff --git a/backend/tests/test_take_state.py b/backend/tests/test_take_state.py
index c02e1cb..49429d5 100644
--- a/backend/tests/test_take_state.py
+++ b/backend/tests/test_take_state.py
@@ -15,15 +15,6 @@ the line it was on.
 
     python -m pytest tests/test_take_state.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
@@ -31,9 +22,10 @@ from fastapi.testclient import TestClient
 from app import auth, limits, models
 from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
-from app.providers import PromptParts
 from app.routers import adventures
 
+from fakes import ScriptedProvider
+
 SCHEMA = {"player": {"hp": {"min": 0, "max": 100, "initial": 100}}}
 
 # Ten gold a turn, every turn. A number that only ever increases makes a
@@ -48,20 +40,6 @@ modifier(text);
 """
 
 
-class ScriptedProvider:
-    last_usage = None
-    replies: list = []
-    calls = 0
-
-    def __init__(self, *a, **k):
-        pass
-
-    async def generate(self, parts: PromptParts, *, temperature, max_tokens):
-        index = min(ScriptedProvider.calls, len(ScriptedProvider.replies) - 1)
-        ScriptedProvider.calls += 1
-        yield ("text", ScriptedProvider.replies[index])
-
-
 @pytest.fixture()
 def client(monkeypatch):
     Base.metadata.create_all(bind=engine)
diff --git a/backend/tests/test_tree_migration.py b/backend/tests/test_tree_migration.py
index e775b59..05746b8 100644
--- a/backend/tests/test_tree_migration.py
+++ b/backend/tests/test_tree_migration.py
@@ -16,14 +16,7 @@ place, would silently skip the DDL and test only half the change.
     python -m pytest tests/test_tree_migration.py -v
 """
 import json
-import os
-import tempfile
 
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
 
 import pytest
 from fastapi import Depends
diff --git a/backend/tests/test_turn_flow_integration.py b/backend/tests/test_turn_flow_integration.py
index c5745f4..0630065 100644
--- a/backend/tests/test_turn_flow_integration.py
+++ b/backend/tests/test_turn_flow_integration.py
@@ -7,15 +7,6 @@ adventure's stored gold total stays correct across play, undo, and retry.
 
     python -m pytest tests/test_turn_flow_integration.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
@@ -23,9 +14,10 @@ from fastapi.testclient import TestClient
 from app import auth, limits, models
 from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
-from app.providers import PromptParts
 from app.routers import adventures
 
+from fakes import ScriptedProvider
+
 GOLD_SCRIPT = """
 const modifier = (text) => {
   state.gold = (state.gold || 0) + 10;
@@ -35,14 +27,7 @@ modifier(text);
 """
 
 
-class FakeProvider:
-    """Stand-in for OpenAICompatibleProvider: streams one fixed line, no network."""
-    last_usage = None
-    def __init__(self, *a, **k):
-        pass
-
-    async def generate(self, parts: PromptParts, *, temperature, max_tokens):
-        yield ("text", "The torch flickers as you press onward.")
+AI_REPLY = "The torch flickers as you press onward."
 
 
 @pytest.fixture()
@@ -66,7 +51,8 @@ def client(monkeypatch):
     setup.close()
 
     # Force a real, non-demo turn that uses the fake provider.
-    monkeypatch.setattr(adventures, "OpenAICompatibleProvider", FakeProvider)
+    ScriptedProvider.replies = [AI_REPLY]
+    monkeypatch.setattr(adventures, "OpenAICompatibleProvider", ScriptedProvider)
     monkeypatch.setattr(auth, "resolve_provider_config", lambda s: auth.ProviderConfig(
         "http://fake", "k", "test-model", False))
     monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)
diff --git a/backend/tests/test_worldstate_integration.py b/backend/tests/test_worldstate_integration.py
index 87a195f..1054344 100644
--- a/backend/tests/test_worldstate_integration.py
+++ b/backend/tests/test_worldstate_integration.py
@@ -4,15 +4,6 @@ undo rolling the world state back.
 
     python -m pytest tests/test_worldstate_integration.py -v
 """
-import os
-import tempfile
-
-_tmp = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
-_tmp.close()
-os.environ["AIDND_DB_PATH"] = _tmp.name
-os.environ.pop("AIDND_DATABASE_URL", None)
-os.environ.pop("DATABASE_URL", None)
-
 import pytest
 from fastapi import Depends
 from fastapi.testclient import TestClient
@@ -20,9 +11,10 @@ from fastapi.testclient import TestClient
 from app import auth, limits, models
 from app.database import Base, SessionLocal, engine, get_db
 from app.main import app
-from app.providers import PromptParts
 from app.routers import adventures
 
+from fakes import ScriptedProvider
+
 SCHEMA = {
     "player": {"hp": {"min": 0, "max": 100, "initial": 100, "max_delta_per_turn": 30}},
     "npcs": {
@@ -45,15 +37,6 @@ AI_REPLY = (
 )
 
 
-class FakeProvider:
-    last_usage = None
-    def __init__(self, *a, **k):
-        pass
-
-    async def generate(self, parts: PromptParts, *, temperature, max_tokens):
-        yield ("text", AI_REPLY)
-
-
 @pytest.fixture()
 def client(monkeypatch):
     Base.metadata.create_all(bind=engine)
@@ -78,7 +61,8 @@ def client(monkeypatch):
     adv_id, user_id = adv.id, user.id
     setup.close()
 
-    monkeypatch.setattr(adventures, "OpenAICompatibleProvider", FakeProvider)
+    ScriptedProvider.replies = [AI_REPLY]
+    monkeypatch.setattr(adventures, "OpenAICompatibleProvider", ScriptedProvider)
     monkeypatch.setattr(auth, "resolve_provider_config", lambda s: auth.ProviderConfig(
         "http://fake", "k", "test-model", False))
     monkeypatch.setattr(limits, "rate_limit", lambda *a, **k: None)