Add documentation for prompt templates and getSuggestedTitle function (#159)

README.md

@@ -184,6 +184,7 @@ paperless-gpt’s flexible **prompt templates** let you shape how AI responds:
 1. **`title_prompt.tmpl`**: For document titles.  
 2. **`tag_prompt.tmpl`**: For tagging logic.
 3. **`ocr_prompt.tmpl`**: For LLM OCR.
+4. **`correspondent_prompt.tmpl`**: For correspondent identification.
 
 Mount them into your container via:
 
@@ -194,6 +195,34 @@ Mount them into your container via:
 
 Then tweak at will—**paperless-gpt** reloads them automatically on startup!
 
+#### Template Variables
+
+Each template has access to specific variables:
+
+**title_prompt.tmpl**:
+- `{{.Language}}` - Target language (e.g., "English")
+- `{{.Content}}` - Document content text
+- `{{.Title}}` - Original document title
+
+**tag_prompt.tmpl**:
+- `{{.Language}}` - Target language
+- `{{.AvailableTags}}` - List of existing tags in paperless-ngx
+- `{{.OriginalTags}}` - Document's current tags
+- `{{.Title}}` - Document title
+- `{{.Content}}` - Document content text
+
+**ocr_prompt.tmpl**:
+- `{{.Language}}` - Target language
+
+**correspondent_prompt.tmpl**:
+- `{{.Language}}` - Target language
+- `{{.AvailableCorrespondents}}` - List of existing correspondents
+- `{{.BlackList}}` - List of blacklisted correspondent names
+- `{{.Title}}` - Document title
+- `{{.Content}}` - Document content text
+
+The templates use Go's text/template syntax. paperless-gpt automatically reloads template changes on startup.
+
 ---
 
 ## Usage

app_llm.go

@@ -191,7 +191,7 @@ func (app *App) doOCRViaLLM(ctx context.Context, jpegBytes []byte, logger *logru
 }
 
 // getSuggestedTitle generates a suggested title for a document using the LLM
-func (app *App) getSuggestedTitle(ctx context.Context, content string, suggestedTitle string, logger *logrus.Entry) (string, error) {
+func (app *App) getSuggestedTitle(ctx context.Context, content string, originalTitle string, logger *logrus.Entry) (string, error) {
 	likelyLanguage := getLikelyLanguage()
 
 	templateMutex.RLock()
@@ -201,7 +201,7 @@ func (app *App) getSuggestedTitle(ctx context.Context, content string, suggested
 	err := titleTemplate.Execute(&promptBuffer, map[string]interface{}{
 		"Language": likelyLanguage,
 		"Content":  content,
-		"Title":    suggestedTitle,
+		"Title":    originalTitle,
 	})
 	if err != nil {
 		return "", fmt.Errorf("error executing title template: %v", err)