support raw generation requests (#952)

- add the optional `raw` generate request parameter to bypass prompt formatting and response context
-add raw request to docs

server/routes.go

@@ -158,9 +158,14 @@ func GenerateHandler(c *gin.Context) {
 		return
 	}
 
-	if req.Model == "" {
+	// validate the request
+	switch {
+	case req.Model == "":
 		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"error": "model is required"})
 		return
+	case req.Raw && (req.Template != "" || req.System != "" || len(req.Context) > 0):
+		c.AbortWithStatusJSON(http.StatusBadRequest, gin.H{"error": "raw mode does not support template, system, or context"})
+		return
 	}
 
 	model, err := GetModel(req.Model)
@@ -189,10 +194,13 @@ func GenerateHandler(c *gin.Context) {
 
 	checkpointLoaded := time.Now()
 
-	prompt, err := model.Prompt(req)
-	if err != nil {
-		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
-		return
+	prompt := req.Prompt
+	if !req.Raw {
+		prompt, err = model.Prompt(req)
+		if err != nil {
+			c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+			return
+		}
 	}
 
 	ch := make(chan any)
@@ -215,6 +223,11 @@ func GenerateHandler(c *gin.Context) {
 				r.LoadDuration = checkpointLoaded.Sub(checkpointStart)
 			}
 
+			if req.Raw {
+				// in raw mode the client must manage history on their own
+				r.Context = nil
+			}
+
 			ch <- r
 		}