PR #801 follow-up: default-config template contradicted the retry engine's documented default

CI failed all 7 requeue tests that passed locally. Root cause is a real
shipping bug, not test flake: config/settings.py's default template set
retry_next_candidate_on_mismatch: False ("Default off — opt-in") while the
monitor reads it with inline default True and the PR documents it as ON.
Outcome split the userbase: a FRESH install (or CI's clean runner) gets the
template key = retry engine silently OFF; an existing config.json lacks the
key = inline True wins = engine ON. Same code, opposite behavior, decided by
install age.

- template aligned to True (the documented + approved default; existing
  installs already behave this way via the inline default)
- the requeue tests now pin the toggle ON via the wiring helper instead of
  reading the runner's ambient config — CI's fresh defaults vs a dev's
  lived-in config.json must never decide whether they pass. _patch_config
  composes (it wraps the pinned get and falls through).

64 retry-engine tests pass; fresh-default simulation confirms the toggle
resolves True.

config/settings.py

@@ -497,8 +497,12 @@ class ConfigManager:
             "post_processing": {
                 # When a download is quarantined (AcoustID mismatch, integrity /
                 # duration failure), retry the next-best candidate instead of
-                # failing outright. Default off — opt-in.
-                "retry_next_candidate_on_mismatch": False,
+                # failing outright. Default ON (PR #801's documented default —
+                # the monitor reads this with inline default True; this template
+                # said False, so fresh installs silently shipped with the retry
+                # engine off while existing configs got it on. CI caught the
+                # split: its fresh default config failed all 7 requeue tests).
+                "retry_next_candidate_on_mismatch": True,
                 # Opt-in exhaustive retry: budget retries PER SOURCE so every
                 # source (Soulseek, then HiFi/Tidal/…) gets its own attempts
                 # before the track gives up. Default off (single global cap).

tests/imports/test_import_pipeline.py

@@ -326,6 +326,18 @@ def _wire_retry_engine(monkeypatch):
     monkeypatch.setattr(monitor, "missing_download_executor", _Exec())
     monkeypatch.setattr(monitor, "_download_track_worker", lambda task_id, batch_id: None)
     monkeypatch.setattr(monitor, "MAX_QUARANTINE_RETRIES", 5)
+
+    # Pin the retry toggle ON instead of reading the runner's ambient config —
+    # CI's fresh default config vs a dev's lived-in config.json must not
+    # decide whether these tests pass (they did: 7 failures, CI-only).
+    real_get = monitor.config_manager.get
+
+    def _pinned_get(key, default=None):
+        if key == "post_processing.retry_next_candidate_on_mismatch":
+            return True
+        return real_get(key, default)
+
+    monkeypatch.setattr(monitor.config_manager, "get", _pinned_get)
     return submitted