Add Happy 404, featured/related sidebars, and next-post nav to the post page

Happy 404: an HTML 404 (unmatched route, or an explicit not-found inside a
real route) now renders a random existing post instead of the error page,
using the exact same context builder as a real post view. Toggle is the
happy_404_enabled site setting (default on, /admin/settings); JSON/API
requests and a handful of excluded prefixes are never affected. The pool of
candidate slugs is cached in-process and resampled periodically so it stays
fast and eventually cycles the whole posts table; on any internal failure it
falls straight through to the real 404 page.

Applying this everywhere surfaced ~60 existing tests that asserted a literal
404 for a legitimate resource-not-found flow (deleted post, unknown
container, wrong project slug, etc.) - each now disables the setting for the
duration of that specific check and restores it after, so the underlying
not-found behavior stays covered independently of the new feature.

Post page also gained, all built on the same shared post_page_context() so
they render identically on both a real post and a happy-404 page:
- A left sidebar (three separate cards, matching /feed's sidebar-card
  convention) for "Gists from {author}", "Projects from {author}" (private
  projects filtered through the normal visibility check), and "Related
  Discussions" - each cached per author and invalidated on create/edit/
  delete so new content shows up immediately.
- A right column reusing /feed's exact Daily Topic widget class for up to
  three "Featured" articles (the existing but previously-unused `featured`
  news flag), cached as a pool with per-request random sampling.
- A "Next post -> " link beside "Back to Feed", pointing at the next older
  post site-wide (blocked authors skipped). Wired through the same next_url
  mechanism already used for listing pagination, so it emits a real
  backend-rendered <link rel="next"> tag for SEO, not just a visible link.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BWJy6PrMMt5hwWxQwia2rd

tests/api/admin/awards.py

@@ -1,12 +1,13 @@
 # retoor <retoor@molodetz.nl>
 
 import io
+import time
 import requests
 from datetime import datetime, timezone
 from PIL import Image
-from tests.conftest import BASE_URL
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
 from devplacepy.attachments import store_attachment
-from devplacepy.database import get_table
+from devplacepy.database import get_table, set_setting
 from devplacepy.utils import generate_uid, make_combined_slug
 
 JSON = {"Accept": "application/json"}
@@ -87,7 +88,13 @@ def test_admin_revoke_soft_deletes_and_recomputes(seeded_db):
     assert get_table("attachments").find_one(uid=att512).get("deleted_at")
     bob = get_table("users").find_one(username="bob_test")
     assert bob.get("award_count") == 0
-    assert requests.get(f"{BASE_URL}/awards/{slug}/64").status_code == 404
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        assert requests.get(f"{BASE_URL}/awards/{slug}/64").status_code == 404
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def test_media_gallery_hides_revoked_attachment(seeded_db):

tests/api/admin/bots/index.py

@@ -1,8 +1,10 @@
 # retoor <retoor@molodetz.nl>
 
+import time
+
 import requests
-from tests.conftest import BASE_URL
-from devplacepy.database import get_table, refresh_snapshot
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import get_table, refresh_snapshot, set_setting
 
 JSON = {"Accept": "application/json"}
 
@@ -49,8 +51,14 @@ def test_bots_data_shape_for_admin(app_server, seeded_db):
 
 def test_bots_frame_missing_is_404(app_server, seeded_db):
     admin = _admin()
-    r = admin.get(f"{BASE_URL}/admin/bots/999/frame.jpg", allow_redirects=False)
-    assert r.status_code == 404
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        r = admin.get(f"{BASE_URL}/admin/bots/999/frame.jpg", allow_redirects=False)
+        assert r.status_code == 404
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def test_bots_frame_requires_admin(app_server, seeded_db):

tests/api/admin/media/purge.py

@@ -1,11 +1,12 @@
 # retoor <retoor@molodetz.nl>
 
 import io
+import time
 import uuid
 import requests
 from PIL import Image
-from tests.conftest import BASE_URL
-from devplacepy.database import get_table
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import get_table, set_setting
 JSON_media = {"Accept": "application/json"}
 def _png_bytes_media(color=(200, 30, 30)):
     buf = io.BytesIO()
@@ -130,4 +131,10 @@ def test_admin_purge_hard_deletes(seeded_db):
     # row gone (not in trash, cannot restore) and file removed from disk
     trash = admin.get(f"{BASE_URL}/admin/media", headers=JSON_media).json()
     assert all(m["uid"] != uid for m in trash["media"])
-    assert owner.get(f"{BASE_URL}{file_url}").status_code == 404
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        assert owner.get(f"{BASE_URL}{file_url}").status_code == 404
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)

tests/api/admin/trash/restore.py

@@ -2,7 +2,8 @@
 
 import time
 import requests
-from tests.conftest import BASE_URL
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import set_setting
 
 JSON_trash = {"Accept": "application/json"}
 _counter_trash = [0]
@@ -146,7 +147,13 @@ def test_restore_revoked_award_recomputes_stats(seeded_db):
     row = get_table("users").find_one(uid=bob["uid"])
     assert row.get("award_count") == 1
     assert row.get("last_award_uid") == uid
-    assert requests.get(f"{BASE_URL}/awards/{slug}/256").status_code in (302, 404)
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        assert requests.get(f"{BASE_URL}/awards/{slug}/256").status_code in (302, 404)
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def _create_quiz_trash(session):

tests/api/awards/index.py

@@ -1,15 +1,26 @@
 # retoor <retoor@molodetz.nl>
 
 import io
+import time
+import pytest
 import requests
 from datetime import datetime, timezone
 from PIL import Image
-from tests.conftest import BASE_URL
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
 from devplacepy.attachments import store_attachment
-from devplacepy.database import get_table
+from devplacepy.database import get_table, set_setting
 from devplacepy.utils import generate_uid, make_combined_slug
 
 
+@pytest.fixture(scope="module", autouse=True)
+def _disable_happy_404(app_server):
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+
+
 def _png():
     buf = io.BytesIO()
     Image.new("RGBA", (32, 32), (20, 40, 60, 255)).save(buf, format="PNG")

tests/api/battles/events.py

@@ -5,7 +5,8 @@ import time
 import requests
 
 from tests.api.battles._helpers import _create_war_post, _fight, _join, _session_battles
-from tests.conftest import BASE_URL
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import set_setting
 
 
 def test_events_ordered_and_incremental(app_server):
@@ -39,5 +40,11 @@ def test_events_ordered_and_incremental(app_server):
 
 
 def test_events_unknown_battle_404(app_server):
-    r = requests.get(f"{BASE_URL}/battles/nope/events")
-    assert r.status_code == 404
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        r = requests.get(f"{BASE_URL}/battles/nope/events")
+        assert r.status_code == 404
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)

tests/api/block/visibility.py

@@ -4,8 +4,8 @@ import time
 from uuid import uuid4
 from datetime import datetime, timezone
 import requests
-from tests.conftest import BASE_URL
-from devplacepy.database import get_table
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import get_table, set_setting
 from devplacepy.utils import make_combined_slug
 
 JSON = {"Accept": "application/json"}
@@ -110,8 +110,14 @@ def test_blocked_author_post_detail_404(app_server):
     post = _new_post(author_session)
     blocker_session.post(f"{BASE_URL}/block/{author}", allow_redirects=False)
 
-    r = blocker_session.get(f"{BASE_URL}/posts/{post['slug']}")
-    assert r.status_code == 404
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        r = blocker_session.get(f"{BASE_URL}/posts/{post['slug']}")
+        assert r.status_code == 404
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def test_blocked_author_comment_hidden_on_detail(app_server):

tests/api/containers.py

@@ -1,10 +1,11 @@
 # retoor <retoor@molodetz.nl>
 
 from datetime import timedelta
+import time
 import pytest
 import requests
-from tests.conftest import BASE_URL, run_async
-from devplacepy.database import db, get_table, init_db, refresh_snapshot
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS, run_async
+from devplacepy.database import db, get_table, init_db, refresh_snapshot, set_setting
 from devplacepy import config, project_files
 from devplacepy.services.containers import api, store, runtime
 from devplacepy.services.containers.backend.base import Mount, PortMapping, RunSpec
@@ -98,12 +99,16 @@ def test_http_ingress_proxy(app_server):
         }
     )
     refresh_snapshot()
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
     try:
         r = requests.get(f"{BASE_URL}/p/{slug}/foo")
         assert r.status_code == 200, r.text
         assert "hello from upstream" in r.text and "/foo" in r.text
         assert requests.get(f"{BASE_URL}/p/does-not-exist-slug").status_code == 404
     finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
         httpd.shutdown()
         get_table("instances").delete(uid=uid)
         refresh_snapshot()

tests/api/content/permissions.py

@@ -3,7 +3,7 @@
 import time
 import pytest
 import requests
-from tests.conftest import BASE_URL
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
 from devplacepy.database import get_table, refresh_snapshot, set_setting
 
 JSON = {"Accept": "application/json"}
@@ -19,9 +19,13 @@ def _perm_settings(app_server):
         "maintenance_mode": "0",
         "max_attachments_per_resource": "10",
         "allowed_file_types": "",
+        "happy_404_enabled": "0",
     }.items():
         set_setting(key, value)
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
     yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def _member():

tests/api/docs/downloadmd.py

@@ -3,11 +3,24 @@
 import html
 import json
 import re
+import time
+import pytest
 import requests
-from tests.conftest import BASE_URL
-from devplacepy.database import get_table
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import get_table, set_setting
 from devplacepy.docs_api import API_GROUPS
 from devplacepy.utils import clear_user_cache
+
+
+@pytest.fixture(scope="module", autouse=True)
+def _disable_happy_404(app_server):
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+
+
 def _configs_by_id(text):
     configs = re.findall(r"data-config='(.*?)'", text, re.S)
     return {

tests/api/docs/index.py

@@ -4,7 +4,7 @@ import time
 from datetime import datetime, timezone
 import pytest
 import requests
-from tests.conftest import BASE_URL
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
 from devplacepy.database import get_table, refresh_snapshot, set_setting
 from devplacepy.utils import generate_uid, make_combined_slug
 JSON_audit_log = {"Accept": "application/json"}
@@ -29,9 +29,13 @@ def _audit_test_settings(app_server):
         "session_remember_days": "30",
         "news_service_interval": "3600",
         "news_grade_threshold": "7",
+        "happy_404_enabled": "0",
     }.items():
         set_setting(key, value)
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
     yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 def _db_user(name):
     # the user is created by the server subprocess; refresh the test-process
     # SQLite snapshot before reading it back across the process boundary.

tests/api/error/pages.py

@@ -1,10 +1,80 @@
 # retoor <retoor@molodetz.nl>
 
+import time
+
 import requests
-from tests.conftest import BASE_URL
+
+from devplacepy.database import set_setting
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+
+JSON = {"Accept": "application/json"}
+
+
+def _set_happy_404(enabled: bool) -> None:
+    set_setting("happy_404_enabled", "1" if enabled else "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+
+
+def _login(seeded_db, who="alice"):
+    creds = seeded_db[who]
+    session = requests.Session()
+    session.post(
+        f"{BASE_URL}/auth/login",
+        data={"email": creds["email"], "password": creds["password"]},
+    )
+    return session
 
 
 def test_404_renders_error_page(app_server):
-    r = requests.get(f"{BASE_URL}/this-page-does-not-exist-xyz")
+    _set_happy_404(False)
+    try:
+        r = requests.get(f"{BASE_URL}/this-page-does-not-exist-xyz")
+        assert r.status_code == 404
+        assert "404" in r.text or "not found" in r.text.lower()
+    finally:
+        _set_happy_404(True)
+
+
+def test_happy_404_renders_a_real_post(app_server, seeded_db):
+    session = _login(seeded_db)
+    title = f"Happy404 Marker {int(time.time() * 1000)}"
+    created = session.post(
+        f"{BASE_URL}/posts/create",
+        headers=JSON,
+        data={
+            "title": title,
+            "content": "content seeded so the happy 404 pool has something to pick.",
+            "topic": "devlog",
+        },
+    ).json()["data"]
+    assert created["uid"]
+
+    _set_happy_404(True)
+    r = requests.get(f"{BASE_URL}/this-path-was-never-registered-anywhere")
+    assert r.status_code == 200
+    assert 'class="post-detail"' in r.text
+    assert "Page not found" not in r.text
+    assert 'name="robots" content="noindex,nofollow"' in r.text
+
+
+def test_happy_404_disabled_falls_back_to_error_page(app_server):
+    _set_happy_404(False)
+    try:
+        r = requests.get(f"{BASE_URL}/another-path-that-does-not-exist")
+        assert r.status_code == 404
+        assert "Page not found" in r.text
+    finally:
+        _set_happy_404(True)
+
+
+def test_happy_404_never_applies_to_json_requests():
+    _set_happy_404(True)
+    r = requests.get(f"{BASE_URL}/yet-another-missing-path", headers=JSON)
+    assert r.status_code == 404
+    assert r.json()["error"]["status"] == 404
+
+
+def test_happy_404_never_applies_to_api_paths():
+    _set_happy_404(True)
+    r = requests.get(f"{BASE_URL}/api/this-devrant-route-does-not-exist")
     assert r.status_code == 404
-    assert "404" in r.text or "not found" in r.text.lower()

tests/api/forks.py

@@ -1,14 +1,15 @@
 # retoor <retoor@molodetz.nl>
 
 import asyncio
+import time
 from datetime import datetime, timezone
 from pathlib import Path
 import pytest
-from devplacepy.database import init_db, get_table, refresh_snapshot
+from devplacepy.database import init_db, get_table, refresh_snapshot, set_setting
 from devplacepy import project_files
 from devplacepy.services.jobs import queue
 from devplacepy.services.jobs.fork_service import ForkService
-from tests.conftest import run_async
+from tests.conftest import CACHE_VERSION_PROPAGATION_SECONDS, run_async
 @pytest.fixture(autouse=True)
 def _init_db_fork_jobs():
     init_db()
@@ -109,5 +110,11 @@ def _enqueue(source_uid, owner_uid, title="My Fork"):
 def test_fork_status_http_unknown_returns_404(app_server):
     import requests
     from tests.conftest import BASE_URL
-    r = requests.get(f"{BASE_URL}/forks/nonexistent-uid")
-    assert r.status_code == 404
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        r = requests.get(f"{BASE_URL}/forks/nonexistent-uid")
+        assert r.status_code == 404
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)

tests/api/issues/planning.py

@@ -1,12 +1,13 @@
 # retoor <retoor@molodetz.nl>
 
 import json
+import time
 
 import pytest
 import requests
 
 from devplacepy.database import get_table, refresh_snapshot, set_setting
-from tests.conftest import BASE_URL
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
 
 
 @pytest.fixture(scope="module", autouse=True)
@@ -17,9 +18,13 @@ def _planning_settings(app_server):
     set_setting("gitea_repo", "pydevplace")
     set_setting("gitea_token", "planning-test-token")
     set_setting("issue_ai_enhance", "0")
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
     yield
     set_setting("gitea_base_url", "")
     set_setting("gitea_token", "")
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def _admin(seeded_db):

tests/api/posts/create.py

@@ -4,7 +4,7 @@ import time
 from datetime import datetime, timezone
 import pytest
 import requests
-from tests.conftest import BASE_URL
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
 from devplacepy.database import get_table, refresh_snapshot, set_setting
 from devplacepy.utils import generate_uid, make_combined_slug
 JSON_audit_log = {"Accept": "application/json"}
@@ -29,9 +29,13 @@ def _audit_test_settings(app_server):
         "session_remember_days": "30",
         "news_service_interval": "3600",
         "news_grade_threshold": "7",
+        "happy_404_enabled": "0",
     }.items():
         set_setting(key, value)
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
     yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 def _db_user(name):
     # the user is created by the server subprocess; refresh the test-process
     # SQLite snapshot before reading it back across the process boundary.

tests/api/posts/featured.py

@@ -0,0 +1,118 @@
+# retoor <retoor@molodetz.nl>
+
+import time
+
+import requests
+
+from devplacepy.database import get_table
+from tests.conftest import BASE_URL
+
+JSON = {"Accept": "application/json"}
+_counter = [0]
+
+
+def _unique(prefix="feat"):
+    _counter[0] += 1
+    return f"{prefix}{int(time.time() * 1000)}{_counter[0]}"
+
+
+def _signup():
+    name = _unique("featuser")
+    session = requests.Session()
+    session.post(
+        f"{BASE_URL}/auth/signup",
+        data={
+            "username": name,
+            "email": f"{name}@t.dev",
+            "password": "secret123",
+            "confirm_password": "secret123",
+            "birth_date": "1990-01-01",
+            "accept_terms": "1",
+        },
+        allow_redirects=True,
+    )
+    return session
+
+
+def _new_post(session):
+    return session.post(
+        f"{BASE_URL}/posts/create",
+        headers=JSON,
+        data={
+            "title": _unique("featpost"),
+            "content": "content for the featured topics test post",
+            "topic": "devlog",
+        },
+    ).json()["data"]
+
+
+def _seed_featured_article():
+    uid = _unique("featnews")
+    get_table("news").insert(
+        {
+            "uid": uid,
+            "title": _unique("Featured Article"),
+            "slug": _unique("featured-article"),
+            "external_id": uid,
+            "status": "published",
+            "source_name": "test",
+            "url": "https://example.com/article",
+            "description": "a featured article for the post-page test",
+            "content": "",
+            "synced_at": "2024-01-01T00:00:00",
+            "grade": 5,
+            "ai_grade": 5,
+            "show_on_landing": 0,
+            "featured": 1,
+            "featured_locked": 1,
+            "landing_locked": 0,
+            "author": "",
+            "article_published": "",
+            "image_url": "",
+            "has_unique_image": 0,
+            "deleted_at": None,
+            "deleted_by": None,
+        }
+    )
+    return uid
+
+
+def test_post_page_shows_featured_topics(app_server):
+    session = _signup()
+    post = _new_post(session)
+    _seed_featured_article()
+
+    r = requests.get(f"{BASE_URL}/posts/{post['slug']}")
+    assert r.status_code == 200
+    assert 'class="feed-right"' in r.text
+    assert "daily-topic-card" in r.text
+
+
+def test_post_page_json_includes_featured_topics(app_server):
+    session = _signup()
+    post = _new_post(session)
+    _seed_featured_article()
+
+    r = requests.get(f"{BASE_URL}/posts/{post['slug']}", headers=JSON)
+    assert r.status_code == 200
+    data = r.json()
+    assert "featured_topics" in data
+    assert len(data["featured_topics"]) <= 3
+    assert all("title" in item for item in data["featured_topics"])
+
+
+def test_post_page_featured_topics_pick_varies(app_server):
+    session = _signup()
+    post = _new_post(session)
+    for _ in range(6):
+        _seed_featured_article()
+
+    seen = set()
+    for _ in range(20):
+        r = requests.get(f"{BASE_URL}/posts/{post['slug']}", headers=JSON)
+        assert r.status_code == 200
+        titles = tuple(item["title"] for item in r.json()["featured_topics"])
+        assert len(titles) == 3
+        assert len(set(titles)) == 3
+        seen.add(titles)
+    assert len(seen) > 1, "featured topics never varied across 20 requests"

tests/api/posts/nextpost.py

@@ -0,0 +1,72 @@
+# retoor <retoor@molodetz.nl>
+
+import time
+
+import requests
+
+from tests.conftest import BASE_URL
+
+JSON = {"Accept": "application/json"}
+_counter = [0]
+
+
+def _unique(prefix="nextpost"):
+    _counter[0] += 1
+    return f"{prefix}{int(time.time() * 1000)}{_counter[0]}"
+
+
+def _signup():
+    name = _unique("nextuser")
+    session = requests.Session()
+    session.post(
+        f"{BASE_URL}/auth/signup",
+        data={
+            "username": name,
+            "email": f"{name}@t.dev",
+            "password": "secret123",
+            "confirm_password": "secret123",
+            "birth_date": "1990-01-01",
+            "accept_terms": "1",
+        },
+        allow_redirects=True,
+    )
+    return session
+
+
+def _new_post(session, title=None):
+    return session.post(
+        f"{BASE_URL}/posts/create",
+        headers=JSON,
+        data={
+            "title": title or _unique("nextpostbody"),
+            "content": "content for the next-post navigation test",
+            "topic": "devlog",
+        },
+    ).json()["data"]
+
+
+def test_newer_post_links_to_the_next_older_post(app_server):
+    session = _signup()
+    older = _new_post(session, title="Older Post For Next Nav")
+    newer = _new_post(session, title="Newer Post For Next Nav")
+
+    r = requests.get(f"{BASE_URL}/posts/{newer['slug']}", headers=JSON)
+    assert r.status_code == 200
+    assert r.json()["next_post_url"] == f"/posts/{older['slug']}"
+
+    html = requests.get(f"{BASE_URL}/posts/{newer['slug']}")
+    assert f'href="/posts/{older["slug"]}" class="back-link next-post-link"' in html.text
+    assert f'<link rel="next" href="{BASE_URL}/posts/{older["slug"]}">' in html.text
+
+
+def test_next_post_link_is_absent_when_the_url_is_none(app_server):
+    session = _signup()
+    post = _new_post(session)
+
+    data = requests.get(f"{BASE_URL}/posts/{post['slug']}", headers=JSON).json()
+    html = requests.get(f"{BASE_URL}/posts/{post['slug']}").text
+    if data["next_post_url"] is None:
+        assert "next-post-link" not in html
+        assert 'rel="next"' not in html
+    else:
+        assert f'href="{data["next_post_url"]}" class="back-link next-post-link"' in html

tests/api/posts/sidebar.py

@@ -0,0 +1,138 @@
+# retoor <retoor@molodetz.nl>
+
+import time
+
+import requests
+
+from tests.conftest import BASE_URL
+
+JSON = {"Accept": "application/json"}
+_counter = [0]
+
+
+def _unique(prefix="side"):
+    _counter[0] += 1
+    return f"{prefix}{int(time.time() * 1000)}{_counter[0]}"
+
+
+def _signup():
+    name = _unique("sideuser")
+    session = requests.Session()
+    session.post(
+        f"{BASE_URL}/auth/signup",
+        data={
+            "username": name,
+            "email": f"{name}@t.dev",
+            "password": "secret123",
+            "confirm_password": "secret123",
+            "birth_date": "1990-01-01",
+            "accept_terms": "1",
+        },
+        allow_redirects=True,
+    )
+    return session, name
+
+
+def _new_post(session):
+    return session.post(
+        f"{BASE_URL}/posts/create",
+        headers=JSON,
+        data={
+            "title": _unique("sidepost"),
+            "content": "content for the author-sidebar test post",
+            "topic": "devlog",
+        },
+    ).json()["data"]
+
+
+def _new_gist(session, title=None):
+    return session.post(
+        f"{BASE_URL}/gists/create",
+        headers=JSON,
+        data={
+            "title": title or _unique("sidegist"),
+            "description": "a gist used for the author sidebar test",
+            "source_code": "print('hi')",
+            "language": "python",
+        },
+    ).json()["data"]
+
+
+def _new_project(session, title=None, is_private=None):
+    data = {
+        "title": title or _unique("sideproj"),
+        "description": "a project used for the author sidebar test",
+        "project_type": "software",
+        "status": "In Development",
+        "platforms": "",
+    }
+    created = session.post(f"{BASE_URL}/projects/create", headers=JSON, data=data).json()["data"]
+    if is_private:
+        session.post(
+            f"{BASE_URL}/projects/{created['slug']}/private",
+            headers=JSON,
+            data={"value": "true"},
+        )
+    return created
+
+
+def test_post_page_has_no_author_cards_with_nothing_else(app_server):
+    session, name = _signup()
+    post = _new_post(session)
+    r = requests.get(f"{BASE_URL}/posts/{post['slug']}")
+    assert r.status_code == 200
+    assert f"Gists from {name}" not in r.text
+    assert f"Projects from {name}" not in r.text
+
+
+def test_post_page_shows_author_gists_and_projects(app_server):
+    session, name = _signup()
+    post = _new_post(session)
+    _new_gist(session, title="Alpha Gist")
+    _new_project(session, title="Alpha Project")
+
+    r = requests.get(f"{BASE_URL}/posts/{post['slug']}")
+    assert r.status_code == 200
+    assert f"Gists from {name}" in r.text
+    assert f"Projects from {name}" in r.text
+    assert "Alpha Gist" in r.text
+    assert "Alpha Project" in r.text
+
+
+def test_post_page_sidebar_json_parity_and_limit(app_server):
+    session, name = _signup()
+    post = _new_post(session)
+    for i in range(7):
+        _new_gist(session, title=f"Gist {i}")
+
+    r = requests.get(f"{BASE_URL}/posts/{post['slug']}", headers=JSON)
+    assert r.status_code == 200
+    data = r.json()
+    assert len(data["author_gists"]) == 5
+    assert data["author_projects"] == []
+
+
+def test_post_page_hides_private_project_from_stranger(app_server):
+    session, name = _signup()
+    post = _new_post(session)
+    _new_project(session, title="Hidden Project", is_private=True)
+
+    stranger = requests.Session()
+    r = stranger.get(f"{BASE_URL}/posts/{post['slug']}", headers=JSON)
+    assert r.status_code == 200
+    titles = [p["title"] for p in r.json()["author_projects"]]
+    assert "Hidden Project" not in titles
+
+
+def test_post_page_sidebar_updates_live_after_new_gist(app_server):
+    session, name = _signup()
+    post = _new_post(session)
+
+    r0 = requests.get(f"{BASE_URL}/posts/{post['slug']}", headers=JSON)
+    assert r0.json()["author_gists"] == []
+
+    _new_gist(session, title="Just Created Gist")
+
+    r1 = requests.get(f"{BASE_URL}/posts/{post['slug']}", headers=JSON)
+    titles = [g["title"] for g in r1.json()["author_gists"]]
+    assert "Just Created Gist" in titles

tests/api/profile/delete.py

@@ -2,15 +2,25 @@
 
 import time
 
+import pytest
 import requests
 
-from devplacepy.database import get_table, refresh_snapshot
-from tests.conftest import BASE_URL
+from devplacepy.database import get_table, refresh_snapshot, set_setting
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
 
 JSON = {"Accept": "application/json"}
 _counter = [0]
 
 
+@pytest.fixture(scope="module", autouse=True)
+def _disable_happy_404(app_server):
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+
+
 def _unique(prefix="del"):
     _counter[0] += 1
     return f"{prefix}{int(time.time() * 1000)}{_counter[0]}"

tests/api/profile/index.py

@@ -1,7 +1,11 @@
 # retoor <retoor@molodetz.nl>
 
+import time
+
+import pytest
 import requests
-from tests.conftest import BASE_URL
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import set_setting
 def _seed_news_seo():
     from datetime import datetime, timezone
     from devplacepy.database import get_table
@@ -166,7 +170,16 @@ def _seed_feed_posts(count):
     return topic
 
 
-def test_missing_profile_returns_404(app_server):
+@pytest.fixture()
+def _disable_happy_404(app_server):
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+
+
+def test_missing_profile_returns_404(app_server, _disable_happy_404):
     r = requests.get(f"{BASE_URL}/profile/no-such-user-xyz", allow_redirects=False)
     assert r.status_code == 404
 

tests/api/proxy.py

@@ -1,7 +1,20 @@
 # retoor <retoor@molodetz.nl>
 
+import time
+
+import pytest
 import requests
-from tests.conftest import BASE_URL
+from devplacepy.database import set_setting
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+
+
+@pytest.fixture(scope="module", autouse=True)
+def _disable_happy_404(app_server):
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def test_proxy_unknown_slug_returns_404(app_server):

tests/api/tools/deepsearch/export.py

@@ -1,9 +1,10 @@
 # retoor <retoor@molodetz.nl>
 
 import json
+import time
 import pytest
 import requests
-from tests.conftest import BASE_URL
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
 from devplacepy.database import create_deepsearch_session, get_table, refresh_snapshot, set_setting
 from devplacepy.services.jobs import queue
 
@@ -11,7 +12,11 @@ from devplacepy.services.jobs import queue
 @pytest.fixture(scope="module", autouse=True)
 def _settings(app_server):
     set_setting("rate_limit_per_minute", "1000000")
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
     yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def _weasyprint_available() -> bool:

tests/api/tools/deepsearch/session.py

@@ -1,17 +1,29 @@
 # retoor <retoor@molodetz.nl>
 
 import json
+import time
 
+import pytest
 import requests
-from tests.conftest import BASE_URL
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
 from devplacepy.database import (
     create_deepsearch_session,
     get_table,
     refresh_snapshot,
+    set_setting,
 )
 from devplacepy.services.jobs import queue
 
 
+@pytest.fixture
+def _no_happy_404(app_server):
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+
+
 def _json_headers():
     return {"Accept": "application/json"}
 
@@ -204,6 +216,6 @@ def test_export_json(app_server):
         _clear()
 
 
-def test_export_unknown_uid_404(app_server):
+def test_export_unknown_uid_404(app_server, _no_happy_404):
     r = requests.get(f"{BASE_URL}/tools/deepsearch/nope/export.md")
     assert r.status_code == 404

tests/api/tools/isslop.py

@@ -3,16 +3,26 @@
 import time
 import uuid
 
+import pytest
 import requests
 
-from tests.conftest import BASE_URL
-from devplacepy.database import get_table, refresh_snapshot
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import get_table, refresh_snapshot, set_setting
 from devplacepy.services.jobs.isslop import store
 from devplacepy.utils import generate_uid
 
 _counter_isslop = [0]
 
 
+@pytest.fixture
+def _no_happy_404(app_server):
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+
+
 def _json_headers():
     return {"Accept": "application/json"}
 
@@ -132,7 +142,7 @@ def test_status_unknown_uid_404(app_server):
     assert r.status_code == 404
 
 
-def test_report_json_while_pending(app_server):
+def test_report_json_while_pending(app_server, _no_happy_404):
     session = requests.Session()
     try:
         run = session.post(
@@ -287,7 +297,7 @@ def test_media_route_serves_a_thumbnail(app_server):
         store.purge_analysis(uid)
 
 
-def test_media_route_rejects_a_name_outside_the_hex_pattern(app_server):
+def test_media_route_rejects_a_name_outside_the_hex_pattern(app_server, _no_happy_404):
     uid = generate_uid()
     store.create_analysis(uid, "https://github.com/owner/repository", "guest", "media-traversal-owner")
     try:

tests/api/tools/seo.py

@@ -1,11 +1,23 @@
 # retoor <retoor@molodetz.nl>
 
+import time
+
+import pytest
 import requests
-from tests.conftest import BASE_URL
-from devplacepy.database import get_table, refresh_snapshot
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import get_table, refresh_snapshot, set_setting
 from devplacepy.services.jobs import queue
 
 
+@pytest.fixture(scope="module", autouse=True)
+def _disable_happy_404(app_server):
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+
+
 def _json_headers():
     return {"Accept": "application/json"}
 

tests/api/topics.py

@@ -2,9 +2,10 @@
 
 import time
 from datetime import datetime, timedelta, timezone
+import pytest
 import requests
-from tests.conftest import BASE_URL
-from devplacepy.database import get_table, refresh_snapshot
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import get_table, refresh_snapshot, set_setting
 from devplacepy.database.pagination import PAGE_SIZE
 from devplacepy.utils import generate_uid
 
@@ -12,6 +13,15 @@ JSON_topics = {"Accept": "application/json"}
 _counter_topics = [0]
 
 
+@pytest.fixture
+def _no_happy_404(app_server):
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+
+
 def _session_topics():
     _counter_topics[0] += 1
     name = f"tpc{int(time.time() * 1000)}{_counter_topics[0]}"
@@ -107,7 +117,7 @@ def test_topic_page_lists_only_that_topics_posts(app_server):
     assert showcase_title not in titles
 
 
-def test_topic_page_rejects_an_unknown_topic(app_server):
+def test_topic_page_rejects_an_unknown_topic(app_server, _no_happy_404):
     r = requests.get(f"{BASE_URL}/topics/not-a-real-topic", allow_redirects=False)
     assert r.status_code == 404
 

tests/api/zips/download.py

@@ -6,14 +6,24 @@ import json
 import time
 import zipfile
 from pathlib import Path
+import pytest
 import requests
 from playwright.sync_api import expect
-from tests.conftest import BASE_URL
-from devplacepy.database import get_table, refresh_snapshot
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import get_table, refresh_snapshot, set_setting
 from devplacepy.services.jobs import queue
 from devplacepy.services.jobs.zip_service import ZipService
 from tests.conftest import run_async
 _counter_zip_download = [0]
+
+
+@pytest.fixture(scope="module", autouse=True)
+def _disable_happy_404(app_server):
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 def _signup_zip_download():
     _counter_zip_download[0] += 1
     name = f"zd{int(time.time() * 1000)}{_counter_zip_download[0]}"

tests/conftest.py

@@ -39,6 +39,9 @@ os.environ["DEVPLACE_SITEMAP_TTL"] = "0"
 os.environ["DEVPLACE_HOME_CACHE_TTL"] = "0"
 os.environ["DEVPLACE_RANKING_TTL"] = "0"
 os.environ["DEVPLACE_MARKET_SATURATION_TTL"] = "0"
+os.environ["DEVPLACE_HAPPY_404_POOL_TTL"] = "0"
+os.environ["DEVPLACE_FEATURED_TOPICS_POOL_TTL"] = "0"
+os.environ["DEVPLACE_USER_RECENT_ITEMS_TTL"] = "0"
 
 
 _ASYNC_LOOP = None

tests/e2e/admin/auditlog.py

@@ -2,7 +2,7 @@
 
 from uuid import uuid4
 from datetime import datetime, timezone
-from tests.conftest import BASE_URL
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
 from devplacepy.database import get_table
 from devplacepy.utils import make_combined_slug
 def seed_admin_news(count=3):
@@ -265,10 +265,16 @@ def test_audit_log_view_detail(alice):
 
 def test_audit_log_detail_unknown_404(alice):
     page, _ = alice
-    resp = page.goto(
-        f"{BASE_URL}/admin/audit-log/nonexistent", wait_until="domcontentloaded"
-    )
-    assert resp.status == 404
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        resp = page.goto(
+            f"{BASE_URL}/admin/audit-log/nonexistent", wait_until="domcontentloaded"
+        )
+        assert resp.status == 404
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def test_audit_log_guest_redirects_to_login(page, app_server):

tests/e2e/admin/containers/index.py

@@ -1,9 +1,11 @@
 # retoor <retoor@molodetz.nl>
 
+import time
+
 import requests
 from playwright.sync_api import expect
-from tests.conftest import BASE_URL
-from devplacepy.database import get_table
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import get_table, set_setting
 
 USER_INPUT = '#cm-admin-create-form input[data-search="user"]'
 USER_OPTIONS = '#cm-admin-create-form [data-suggest="user"] li[data-value]'
@@ -29,8 +31,14 @@ def test_containers_admin_page_loads(alice, app_server):
 
 def test_container_instance_page_404_for_missing(alice, app_server):
     page, _ = alice
-    page.goto(f"{BASE_URL}/admin/containers/nonexistent", wait_until="domcontentloaded")
-    assert page.is_visible("text=Not Found") or page.is_visible("text=404")
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        page.goto(f"{BASE_URL}/admin/containers/nonexistent", wait_until="domcontentloaded")
+        assert page.is_visible("text=Not Found") or page.is_visible("text=404")
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def test_user_search_arrow_keys_highlight_and_enter_selects(alice, seeded_db):

tests/e2e/admin/containers/manage.py

@@ -2,12 +2,13 @@
 
 import time
 import requests
-from tests.conftest import BASE_URL, login_user
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS, login_user
 from devplacepy.database import (
     get_table,
     get_primary_admin_uid,
     invalidate_admins_cache,
     refresh_snapshot,
+    set_setting,
 )
 from devplacepy.utils import clear_user_cache
 
@@ -201,11 +202,15 @@ def test_admin_detail_page_404_for_non_viewer_on_private_project(page, app_serve
     other = _make_admin()
     project = _create_project(owner["api_key"], "E2E Manage Detail Private", is_private=True)
     inst_uid = _insert_instance(project["uid"], owner["uid"])
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
     try:
         login_user(page, other)
         page.goto(f"{BASE_URL}/admin/containers/{inst_uid}", wait_until="domcontentloaded")
         assert page.is_visible("text=Not Found") or page.is_visible("text=404")
     finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
         _cleanup(inst_uid)
 
 

tests/e2e/admin/services/data.py

@@ -1,7 +1,9 @@
 # retoor <retoor@molodetz.nl>
 
-from tests.conftest import BASE_URL, login_user
-from devplacepy.database import get_table
+import time
+
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS, login_user
+from devplacepy.database import get_table, set_setting
 def _promote_to_admin(username: str) -> None:
     users = get_table("users")
     user = users.find_one(username=username)
@@ -26,9 +28,15 @@ def test_service_detail_unknown_404(page, seeded_db):
     user = seeded_db["alice"]
     _promote_to_admin(user["username"])
     login_user(page, user)
-    resp = page.request.get(f"{BASE_URL}/admin/services/nope")
-    assert resp.status == 404
-    assert page.request.get(f"{BASE_URL}/admin/services/nope/data").status == 404
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        resp = page.request.get(f"{BASE_URL}/admin/services/nope")
+        assert resp.status == 404
+        assert page.request.get(f"{BASE_URL}/admin/services/nope/data").status == 404
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def test_bots_service_registered_and_opt_in(page, seeded_db):

tests/e2e/docs.py

@@ -3,11 +3,22 @@
 import html
 import json
 import re
+import time
+import pytest
 import requests
-from tests.conftest import BASE_URL
-from devplacepy.database import get_table
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import get_table, set_setting
 from devplacepy.docs_api import API_GROUPS
 from devplacepy.utils import clear_user_cache
+
+
+@pytest.fixture(scope="module", autouse=True)
+def _disable_happy_404(app_server):
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 def _configs_by_id(text):
     configs = re.findall(r"data-config='(.*?)'", text, re.S)
     return {

tests/e2e/feed.py

@@ -1,6 +1,6 @@
 # retoor <retoor@molodetz.nl>
 
-from tests.conftest import BASE_URL, create_post_with_files, paste_image
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS, create_post_with_files, paste_image
 import time
 import requests
 from playwright.sync_api import expect
@@ -11,6 +11,7 @@ from devplacepy.database import (
     list_custom_overrides,
     set_custom_override,
     set_customization_pref,
+    set_setting,
 )
 from devplacepy.utils import clear_user_cache
 def _user_customization_toggle(username):
@@ -851,8 +852,14 @@ def test_delete_own_post(alice):
     page.locator(".post-action-btn:has-text('Delete')").click()
     page.locator(".dialog-overlay.visible .dialog-confirm").click()
     page.wait_for_url(f"{BASE_URL}/feed", wait_until="domcontentloaded")
-    resp = page.goto(post_url, wait_until="domcontentloaded")
-    assert resp.status == 404
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        resp = page.goto(post_url, wait_until="domcontentloaded")
+        assert resp.status == 404
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def test_profile_nav_from_topbar(alice):

tests/e2e/forks.py

@@ -1,9 +1,20 @@
 # retoor <retoor@molodetz.nl>
 
 import json
-from tests.conftest import BASE_URL
-from devplacepy.database import get_table
+import time
+import pytest
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import get_table, set_setting
 from devplacepy.services.jobs import queue
+
+
+@pytest.fixture(scope="module", autouse=True)
+def _disable_happy_404(app_server):
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    yield
+    set_setting("happy_404_enabled", "1")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 def _seed_job(uid="test-fork-uid-001"):
     jobs = get_table("jobs")
     jobs.upsert(

tests/e2e/game/farm.py

@@ -1,11 +1,13 @@
 # retoor <retoor@molodetz.nl>
 
+import time
 from datetime import datetime, timedelta, timezone
 
 from playwright.sync_api import expect
 
-from tests.conftest import BASE_URL
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
 from tests.e2e.game.index import reset_farm, warp_ready
+from devplacepy.database import set_setting
 
 
 def _plant_growing(username, crop="python", slot=0):
@@ -84,10 +86,16 @@ def test_guest_can_view_farm(page):
 
 def test_unknown_farm_is_404(bob):
     page, _ = bob
-    response = page.goto(
-        f"{BASE_URL}/game/farm/nope_nobody", wait_until="domcontentloaded"
-    )
-    assert response is not None and response.status == 404
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        response = page.goto(
+            f"{BASE_URL}/game/farm/nope_nobody", wait_until="domcontentloaded"
+        )
+        assert response is not None and response.status == 404
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def test_ready_build_is_protected_during_grace(bob):

tests/e2e/issues/index.py

@@ -1,6 +1,9 @@
 # retoor <retoor@molodetz.nl>
 
-from tests.conftest import BASE_URL
+import time
+
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import set_setting
 
 
 def test_issues_page_loads(alice):
@@ -61,6 +64,12 @@ def test_issue_button_icon_spacing(alice):
 
 def test_issue_detail_not_configured(alice):
     page, _ = alice
-    page.goto(f"{BASE_URL}/issues/999", wait_until="domcontentloaded")
-    assert page.is_visible("h1.error-code:has-text('404')")
-    assert page.is_visible("text=Page not found")
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        page.goto(f"{BASE_URL}/issues/999", wait_until="domcontentloaded")
+        assert page.is_visible("h1.error-code:has-text('404')")
+        assert page.is_visible("text=Page not found")
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)

tests/e2e/issues/jobs.py

@@ -1,10 +1,19 @@
 # retoor <retoor@molodetz.nl>
 
-from tests.conftest import BASE_URL
+import time
+
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
+from devplacepy.database import set_setting
 
 
 def test_issue_job_status_not_found(alice):
     page, _ = alice
-    page.goto(f"{BASE_URL}/issues/jobs/nonexistent-job", wait_until="domcontentloaded")
-    assert page.is_visible("h1.error-code:has-text('404')")
-    assert page.is_visible("text=Page not found")
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        page.goto(f"{BASE_URL}/issues/jobs/nonexistent-job", wait_until="domcontentloaded")
+        assert page.is_visible("h1.error-code:has-text('404')")
+        assert page.is_visible("text=Page not found")
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)

tests/e2e/news.py

@@ -1,10 +1,12 @@
 # retoor <retoor@molodetz.nl>
 
+import time
+
 import pytest
 from uuid import uuid4
 from datetime import datetime, timedelta, timezone
-from tests.conftest import BASE_URL, assert_share_copies
-from devplacepy.database import get_table
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS, assert_share_copies
+from devplacepy.database import get_table, set_setting
 from devplacepy.utils import make_combined_slug
 def _seed_news_paginated(count):
     news_table = get_table("news")
@@ -258,8 +260,14 @@ def test_news_detail_loads(page, news_article):
 
 
 def test_news_detail_404(page, app_server):
-    page.goto(f"{BASE_URL}/news/nonexistent-article", wait_until="domcontentloaded")
-    assert page.is_visible("text=not found", timeout=5000)
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        page.goto(f"{BASE_URL}/news/nonexistent-article", wait_until="domcontentloaded")
+        assert page.is_visible("text=not found", timeout=5000)
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def test_news_comment(alice, news_article):

tests/e2e/projects/index.py

@@ -4,9 +4,20 @@ import re
 from uuid import uuid4
 from datetime import datetime, timedelta, timezone
 from playwright.sync_api import expect
-from tests.conftest import BASE_URL, assert_share_copies
-from devplacepy.database import get_table
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS, assert_share_copies
+from devplacepy.database import get_table, set_setting
 from devplacepy.utils import make_combined_slug
+
+
+def _goto_expect_404(page, url):
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        resp = page.goto(url, wait_until="domcontentloaded")
+        assert resp.status == 404
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 def _seed_posts(count):
     suite = uuid4().hex[:8]
     topic = f"pag{suite}"
@@ -496,8 +507,7 @@ def test_delete_own_project(alice):
     page.locator(".context-menu-item:has-text('Delete')").click()
     page.locator(".dialog-overlay.visible .dialog-confirm").click()
     page.wait_for_url(f"{BASE_URL}/projects", wait_until="domcontentloaded")
-    resp = page.goto(proj_url, wait_until="domcontentloaded")
-    assert resp.status == 404
+    _goto_expect_404(page, proj_url)
 
 
 def test_project_edit_button(alice):
@@ -850,8 +860,7 @@ def test_data_confirm_accept_proceeds(alice):
     _click_delete(page)
     page.locator(".dialog-overlay.visible .dialog-confirm").click()
     page.wait_for_url(f"{BASE_URL}/projects", wait_until="domcontentloaded")
-    resp = page.goto(proj_url, wait_until="domcontentloaded")
-    assert resp.status == 404
+    _goto_expect_404(page, proj_url)
 
 
 def test_detail_download_button_downloads(app_server, page):

tests/e2e/reports/ui.py

@@ -1,9 +1,11 @@
 # retoor <retoor@molodetz.nl>
 
+import time
+
 from playwright.sync_api import expect
 
-from devplacepy.database import get_table, refresh_snapshot
-from tests.conftest import BASE_URL
+from devplacepy.database import get_table, refresh_snapshot, set_setting
+from tests.conftest import BASE_URL, CACHE_VERSION_PROPAGATION_SECONDS
 
 
 def _create_post(page, content):
@@ -124,10 +126,16 @@ def test_the_legal_pages_render_for_a_guest(page, app_server):
 
 
 def test_the_admin_operations_page_is_hidden_from_a_guest(page, app_server):
-    page.goto(
-        f"{BASE_URL}/docs/moderation-operations.html", wait_until="domcontentloaded"
-    )
-    assert "not found" in page.content().lower()
+    set_setting("happy_404_enabled", "0")
+    time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
+    try:
+        page.goto(
+            f"{BASE_URL}/docs/moderation-operations.html", wait_until="domcontentloaded"
+        )
+        assert "not found" in page.content().lower()
+    finally:
+        set_setting("happy_404_enabled", "1")
+        time.sleep(CACHE_VERSION_PROPAGATION_SECONDS)
 
 
 def test_the_admin_operations_page_renders_for_an_admin(alice):