docs: Superset 6.1 documentation catch-up (security, alerts/reports, theming, config) (#39440)

Co-authored-by: Superset Dev <dev@superset.apache.org>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

docs/admin_docs/configuration/alerts-reports.mdx

@@ -81,6 +81,87 @@ SLACK_CACHE_TIMEOUT = int(timedelta(days=2).total_seconds())
 SLACK_API_RATE_LIMIT_RETRY_COUNT = 5
 ```
 
+### Webhook integration
+
+Superset can send alert and report notifications to any HTTP endpoint — useful for chat platforms, incident management tools, or custom automation.
+
+#### Enabling Webhooks
+
+Enable the feature flag in `superset_config.py`:
+
+```python
+FEATURE_FLAGS = {
+    "ALERT_REPORTS": True,
+    "ALERT_REPORT_WEBHOOK": True,
+}
+```
+
+#### Configuring a Webhook Recipient
+
+When creating or editing an alert or report, select **Webhook** as the notification method and enter your endpoint URL.
+
+#### Payload Format
+
+Superset sends an HTTP POST with `Content-Type: application/json`:
+
+```json
+{
+  "name": "My Alert",
+  "header": {
+    "notification_format": "JSON",
+    "notification_type": "Alert",
+    "notification_source": "Alert",
+    "chart_id": 42,
+    "dashboard_id": null
+  },
+  "text": "Alert condition met: value exceeded threshold",
+  "description": "Monthly revenue dropped below target",
+  "url": "https://your-superset-host/superset/dashboard/1/"
+}
+```
+
+When a report includes file attachments (CSV, PDF, or PNG screenshots), the request is sent as `multipart/form-data` instead. In that case, each top-level payload field (`name`, `text`, `description`, `url`) becomes its own form field, and nested structures like `header` are serialized as a JSON-encoded string in their own field. Every attachment is added as a repeated form field named `files`:
+
+```
+POST /webhook HTTP/1.1
+Content-Type: multipart/form-data; boundary=...
+
+--...
+Content-Disposition: form-data; name="name"
+
+My Alert
+--...
+Content-Disposition: form-data; name="header"
+
+{"notification_format": "JSON", "notification_type": "Alert", ...}
+--...
+Content-Disposition: form-data; name="text"
+
+Alert condition met: value exceeded threshold
+--...
+Content-Disposition: form-data; name="files"; filename="report.csv"
+Content-Type: text/csv
+
+<file bytes>
+--...
+```
+
+Webhook consumers should branch on `Content-Type`: parse the body as JSON when `application/json`, or read the individual form fields (decoding `header` as JSON) when `multipart/form-data`.
+
+#### HTTPS Enforcement
+
+To require HTTPS webhook URLs (recommended for production), set:
+
+```python
+ALERT_REPORTS_WEBHOOK_HTTPS_ONLY = True
+```
+
+When enabled, Superset rejects webhook configurations that use `http://` URLs.
+
+#### Retry Behavior
+
+Superset automatically retries webhook deliveries on `429 Too Many Requests` and `5xx` server errors using exponential backoff.
+
 ### Kubernetes-specific
 
 - You must have a `celery beat` pod running. If you're using the chart included in the GitHub repository under [helm/superset](https://github.com/apache/superset/tree/master/helm/superset), you need to put `supersetCeleryBeat.enabled = true` in your values override.

docs/admin_docs/configuration/configuring-superset.mdx

@@ -472,6 +472,38 @@ FEATURE_FLAGS = {
 
 A current list of feature flags can be found in the [Feature Flags](/admin-docs/configuration/feature-flags) documentation.
 
+## Security Configuration
+
+### HASH_ALGORITHM
+
+Controls the hashing algorithm used for internal checksums and cache keys (thumbnails, cache keys, etc.). The default is `sha256`, which satisfies environments with stricter compliance requirements (e.g., FedRAMP). Set it to `md5` to retain the legacy behavior from older Superset deployments:
+
+```python
+HASH_ALGORITHM = "sha256"  # default; set to "md5" for legacy behavior
+```
+
+A companion `HASH_ALGORITHM_FALLBACKS` list (default: `["md5"]`) lets UUID lookups fall back to older algorithms, which enables gradual migration without breaking existing entries. Set it to `[]` for strict mode (use only `HASH_ALGORITHM`).
+
+:::note
+This setting affects internal Superset operations only, not user passwords or authentication tokens. Changing it in an existing deployment may invalidate cached values but does not require a database migration.
+:::
+
+## SQL Lab Query History Pruning
+
+SQL Lab query history is stored in the metadata database and is **not** pruned by default. To trim older rows, enable the `prune_query` Celery beat task by uncommenting it in `CELERY_BEAT_SCHEDULE` and choosing a retention window:
+
+```python
+CELERY_BEAT_SCHEDULE = {
+    "prune_query": {
+        "task": "prune_query",
+        "schedule": crontab(minute=0, hour=0, day_of_month=1),
+        "kwargs": {"retention_period_days": 180},
+    },
+}
+```
+
+Adjust `retention_period_days` to control how long query rows are kept. Companion opt-in tasks (`prune_logs`, `prune_tasks`) exist for pruning the logs and tasks tables; see the commented-out examples in `superset/config.py`. Without enabling these tasks, the metadata database will grow unbounded over time.
+
 :::resources
 - [Blog: Feature Flags in Apache Superset](https://preset.io/blog/feature-flags-in-apache-superset-and-preset/)
 :::

docs/admin_docs/configuration/theming.mdx

@@ -122,6 +122,17 @@ When `ENABLE_UI_THEME_ADMINISTRATION = True`:
 3. Administrators can change system themes without restarting Superset
 4. Configuration file themes serve as fallbacks when no UI themes are set
 
+### Theme Validation and Fallback
+
+Superset validates theme JSON when it is saved, either through the UI or via configuration. If a theme contains invalid tokens or an unrecognized structure, Superset logs a warning and falls back to the built-in default theme rather than applying a broken configuration. This prevents a bad theme from rendering the application unusable.
+
+The fallback order is:
+1. **UI-configured system theme** (highest priority, if `ENABLE_UI_THEME_ADMINISTRATION = True`)
+2. **`THEME_DEFAULT` / `THEME_DARK`** from `superset_config.py`
+3. **Built-in Superset default theme** (always present as a safety net)
+
+If you see unexpected styling after a config change, check the Superset server logs for theme validation warnings.
+
 ### Copying Themes Between Systems
 
 To export a theme for use in configuration files or another instance:
@@ -143,7 +154,11 @@ Superset supports custom fonts through the theme configuration, allowing you to
 
 ### Default Fonts
 
-By default, Superset uses Inter and Fira Code fonts which are bundled with the application via `@fontsource` packages. These fonts work offline and require no external network calls.
+By default, Superset uses **Inter** for UI text and **IBM Plex Mono** for code (SQL editors, JSON fields, and other monospace contexts). Both fonts are bundled with the application via `@fontsource` packages and work offline without any external network calls.
+
+:::note
+IBM Plex Mono replaced Fira Code as the default code font in Superset 6.1. If you have an existing theme that explicitly sets `fontFamilyCode: "Fira Code, ..."`, you may want to update it.
+:::
 
 ### Configuring Custom Fonts