Browser picker - offer each browser once, not twice

On any upgraded install update_35 has migrated the old per-engine request timeout and
User-Agent into browser configs keyed by the engine name ('html_requests',
'html_webdriver'), so those ids exist in BOTH the built-in engine list and browsers.json.
list_watch_browser_choices() concatenated the two sources, so the watch edit page rendered
the same browser as two radios with the same label - and the group override select did the
same, from its own copy of that concatenation.

Deduplicated by value at the source, keeping each value's first position (built-ins stay in
engine order) with its last label - the saved one, since it is the same browser under the
name the user can actually change. The group override select and the Add-Watch list now
derive from that single list instead of rebuilding or re-deduplicating it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

changedetectionio/blueprint/add_watch_ui/browser_config.py

@@ -91,13 +91,8 @@ def list_visual_browser_choices(datastore):
     """
     from changedetectionio.model.browser_config import list_watch_browser_choices
 
-    # A saved browser config deliberately shares its id with the built-in engine it was
-    # migrated from (see update_35), so the candidate list can name the same browser twice -
-    # keep the later (saved) label, which is the one the user can rename.
-    candidates = {value: label for value, label in list_watch_browser_choices(datastore)
-                  if value != SYSTEM_DEFAULT}
-    choices = [(value, str(label)) for value, label in candidates.items()
-               if is_visual_capable(value, datastore)]
+    choices = [(value, str(label)) for value, label in list_watch_browser_choices(datastore)
+               if value != SYSTEM_DEFAULT and is_visual_capable(value, datastore)]
     logger.debug(f"Add-watch browsers offered for the live preview: "
                  f"{[value for value, _label in choices] or 'none'}")
     return choices

changedetectionio/blueprint/tags/__init__.py

@@ -10,17 +10,13 @@ from changedetectionio.llm.evaluator import get_llm_config as _get_llm_config
 
 
 def _browser_config_choices(datastore):
-    """Browsers the group can override with: the always-present built-in engines, then the
-    user's saved browsers - the same set a watch can pick. No 'None' entry: the enabler
-    checkbox (browser_config_overrides_watch) is what turns the override on/off, and the
-    select is disabled when it's unchecked."""
-    from changedetectionio.model.browser_config import list_builtin_browsers
-    choices = []
-    for b in list_builtin_browsers():
-        choices.append((b['id'], b['label']))
-    for cid, entry in datastore.browser_config_store.all().items():
-        choices.append((cid, entry.get('label') or cid))
-    return choices
+    """Browsers the group can override with: exactly what a watch can pick, minus 'system'.
+
+    No 'None'/'system' entry: the enabler checkbox (browser_config_overrides_watch) is what
+    turns the override on/off, and the select is disabled when it's unchecked."""
+    from changedetectionio.model.browser_config import list_watch_browser_choices
+    return [(value, label) for value, label in list_watch_browser_choices(datastore)
+            if value != 'system']
 
 
 def construct_blueprint(datastore: ChangeDetectionStore):

changedetectionio/model/browser_config.py

@@ -485,13 +485,19 @@ def is_valid_browser_selector(value, datastore, allow_empty=True):
 def list_watch_browser_choices(datastore):
     """(value, label) choices for the watch-level 'Browser' picker:
     system default, the always-present built-in engine browsers, then the user's saved browsers.
+
+    Deduplicated by value, because a saved config legitimately shares a built-in engine's id -
+    update_35 migrated the old per-engine request timeout / User-Agent into configs keyed
+    'html_requests' and 'html_webdriver' - and listing one browser twice is not a choice. The
+    saved label wins: it is the same browser, and that is the name the user can change.
     """
-    choices = [('system', _system_default_label(datastore))]
+    choices = {'system': _system_default_label(datastore)}
     for b in list_builtin_browsers():
-        choices.append((b['id'], b['label']))
+        choices[b['id']] = b['label']
     for cid, entry in datastore.browser_config_store.all().items():
-        choices.append((cid, entry.get('label') or cid))
-    return choices
+        choices[cid] = entry.get('label') or cid
+    # dict keeps each value's first position (built-ins stay in engine order) with its last label
+    return list(choices.items())
 
 
 def _system_default_label(datastore):

changedetectionio/tests/test_browser_config.py

@@ -1008,3 +1008,33 @@ def test_update_36_survives_an_unusable_legacy_endpoint(client, live_server, mea
     assert datastore.browser_config_store.get('extra_browser_Broken') is None
     assert datastore.browser_config_store.get('extra_browser_Good')['browser_config']['connection_url'] \
         == 'wss://good.example:9222'
+
+
+def test_browser_picker_lists_each_browser_once(client, live_server, measure_memory_usage, datastore_path):
+    """A saved config that shares a built-in engine's id must not appear twice in the picker.
+
+    update_35 migrates the old per-engine request timeout / User-Agent into configs keyed
+    'html_requests' / 'html_webdriver', so on any upgraded install those ids exist in BOTH the
+    built-in engine list and browsers.json - which rendered the same browser as two radios on the
+    watch edit page (and in the group override select).
+    """
+    from changedetectionio.model.browser_config import list_watch_browser_choices
+    datastore = client.application.config.get('DATASTORE')
+
+    # Exactly what an upgraded install looks like after update_35
+    datastore.browser_config_store.upsert('html_requests', label='Basic fast Plaintext/HTTP Client',
+                                          base_fetcher='html_requests', browser_config={'timeout': 33})
+
+    values = [value for value, _label in list_watch_browser_choices(datastore)]
+    assert len(values) == len(set(values)), f"each browser must be offered once: {values}"
+    assert values.count('html_requests') == 1
+
+    # ...and the watch edit page renders one radio per browser
+    uuid = datastore.add_watch(url="https://example.com")
+    res = client.get(url_for("ui.ui_edit.edit_page", uuid=uuid))
+    assert res.status_code == 200
+    assert res.data.count(b'name="fetch_backend" type="radio" value="html_requests"') == 1
+
+    # A renamed config wins the label, since it is the same browser under a name the user chose
+    datastore.browser_config_store.update('html_requests', label='Fast plain client')
+    assert dict(list_watch_browser_choices(datastore))['html_requests'] == 'Fast plain client'