Document persistent editable Overview prompts, regeneration and safe publishing

README.md

@@ -681,6 +681,60 @@ docker compose exec -T scene-search python -m scene_search.cli \
   jellyfin-overview --title "Exact Film Title" --restore
 ```
 
+### Customise AI Overview generation prompts
+
+The **Generate Overview** feature now has two editable prompt files, just
+like visual captioning. The **general** prompt is used when the chosen
+style is `general` (or `auto` selects general); the **specialist**
+prompt is used when `auto` selects specialist or you explicitly choose it.
+
+On a standard Tardis installation, their host locations are:
+
+```text
+/opt/jellyfin-search/data/overview_prompt.txt
+/opt/jellyfin-search/data/overview_prompt_specialist.txt
+```
+
+Run `docker compose exec -T scene-search python -m scene_search.cli init`
+to create missing files from the bundled defaults. They are **created only
+when missing**, never overwritten by a later container rebuild or `init`.
+The first Overview generation also creates any missing file automatically.
+
+Edit them directly on the host, for example:
+
+```bash
+nano /opt/jellyfin-search/data/overview_prompt.txt
+nano /opt/jellyfin-search/data/overview_prompt_specialist.txt
+```
+
+The generator reads the relevant prompt **for each new draft**; you don't
+need to restart the container after editing the text. The selected caption
+evidence is appended automatically after the prompt, so **do not paste
+captions or placeholders into the file**. Keep prompts reasonably short,
+especially with `OVERVIEW_NUM_CTX=4096`.
+
+You can override the saved locations in `.env`:
+
+```dotenv
+OVERVIEW_PROMPT_FILE=./data/overview_prompt.txt
+OVERVIEW_SPECIALIST_PROMPT_FILE=./data/overview_prompt_specialist.txt
+```
+
+The prompt text contributes to the Overview draft fingerprint, so
+regenerating after an edit uses the new instructions rather than returning
+the previously cached draft. For **existing unpublished drafts**, select
+**Regenerate unpublished drafts** in the Overview Sync page or run:
+
+```bash
+docker compose exec -T scene-search python -m scene_search.cli jellyfin-overviews --draft --refresh-drafts --limit 20
+```
+
+For a single film use `jellyfin-overview --title "Film" --regenerate`.
+Published Jellyfin Overviews are **never changed automatically**; restore
+the original and explicitly regenerate/publish if you want to replace one.
+Changing these Overview prompts does **not** recaption frames, modify
+Meilisearch or rebuild embeddings.
+
 ### Avoid captions describing the contact sheet
 
 Some visual models introduce captions with boilerplate such as