diff --git a/Source/Chatbook/Actions.wl b/Source/Chatbook/Actions.wl
index 35cbaa08..787497d6 100644
--- a/Source/Chatbook/Actions.wl
+++ b/Source/Chatbook/Actions.wl
@@ -113,7 +113,6 @@ ChatbookAction[ "TabRight"             , args___ ] := catchMine @ TabRight @ arg
 ChatbookAction[ "ToggleFormatting"     , args___ ] := catchMine @ ToggleFormatting @ args;
 ChatbookAction[ "ToolManage"           , args___ ] := catchMine @ ToolManage @ args;
 ChatbookAction[ "WidgetSend"           , args___ ] := catchMine @ WidgetSend @ args;
-ChatbookAction[ name_String            , args___ ] := catchMine @ throwFailure[ "NotImplemented", name, args ];
 ChatbookAction[ args___                          ] := catchMine @ throwInternalFailure @ ChatbookAction @ args;
 
 (* ::**************************************************************************************************************:: *)
@@ -634,8 +633,9 @@ CopyChatObject // endDefinition;
 (*constructChatObject*)
 constructChatObject // beginDefinition;
 
+(* cSpell: ignore bdprompt *)
 constructChatObject[ messages_List ] :=
-    With[ { chat = chatObject @ standardizeMessageKeys @ messages },
+    With[ { chat = Quiet[ ChatObject @ standardizeMessageKeys @ messages, ChatObject::bdprompt ] },
         chat /; MatchQ[ chat, _chatObject ]
     ];
 
@@ -644,8 +644,6 @@ constructChatObject[ messages_List ] :=
 
 constructChatObject // endDefinition;
 
-chatObject := chatObject = Symbol[ "System`ChatObject" ];
-
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsection::Closed:: *)
 (*standardizeMessageKeys*)
diff --git a/Source/Chatbook/ChatMessages.wl b/Source/Chatbook/ChatMessages.wl
index d6bf88be..67ec5f20 100644
--- a/Source/Chatbook/ChatMessages.wl
+++ b/Source/Chatbook/ChatMessages.wl
@@ -9,7 +9,12 @@ BeginPackage[ "Wolfram`Chatbook`ChatMessages`" ];
 Wolfram`Chatbook`CellToChatMessage;
 
 `$chatDataTag;
+`$multimodalMessages;
+`$tokenBudget;
+`$tokenPressure;
 `constructMessages;
+`getTokenizer;
+`resizeMultimodalImage;
 
 Begin[ "`Private`" ];
 
@@ -25,12 +30,22 @@ Needs[ "Wolfram`Chatbook`Prompting`"        ];
 Needs[ "Wolfram`Chatbook`Serialization`"    ];
 Needs[ "Wolfram`Chatbook`Settings`"         ];
 Needs[ "Wolfram`Chatbook`Tools`"            ];
+Needs[ "Wolfram`Chatbook`Utils`"            ];
+
+$ContextAliases[ "tokens`" ] = "Wolfram`LLMFunctions`Utilities`Tokenization`";
 
 (* ::**************************************************************************************************************:: *)
 (* ::Section::Closed:: *)
 (*Configuration*)
-$$validMessageResult  = _Association? AssociationQ | _Missing | Nothing;
-$$validMessageResults = $$validMessageResult | { $$validMessageResult ... };
+$maxMMImageSize          = 512;
+$multimodalMessages      = False;
+$tokenBudget             = 2^13;
+$tokenPressure           = 0.0;
+$reservedTokens          = 500; (* TODO: determine this at submit time *)
+$cellStringBudget        = Automatic;
+$initialCellStringBudget = $defaultMaxCellStringLength;
+$$validMessageResult     = _Association? AssociationQ | _Missing | Nothing;
+$$validMessageResults    = $$validMessageResult | { $$validMessageResult ... };
 
 $$inlineModifierCell = Alternatives[
     Cell[ _, "InlineModifierReference", ___ ],
@@ -188,18 +203,48 @@ applyPromptTemplate // endDefinition;
 (*makeChatMessages*)
 makeChatMessages // beginDefinition;
 
-makeChatMessages[ settings_, { cells___, cell_ ? promptFunctionCellQ } ] := (
+makeChatMessages[ settings_, cells_ ] :=
+    Block[
+        {
+            $multimodalMessages = TrueQ @ settings[ "Multimodal" ],
+            $tokenBudget        = settings[ "MaxContextTokens" ],
+            $tokenPressure      = 0.0
+        },
+        If[ settings[ "BasePrompt" ] =!= None, decreaseTokenBudget[ settings, $fullBasePrompt ] ];
+        (* FIXME: need to account for persona/tool prompting as well *)
+        makeChatMessages0[ settings, cells ]
+    ];
+
+makeChatMessages // endDefinition;
+
+
+makeChatMessages0 // beginDefinition;
+
+makeChatMessages0[ settings_, { cells___, cell_ ? promptFunctionCellQ } ] := (
     Sow[ <| "RawOutput" -> True |>, $chatDataTag ];
     makePromptFunctionMessages[ settings, { cells, cell } ]
 );
 
-makeChatMessages[ settings0_, cells_List ] := Enclose[
-    Module[ { settings, role, message, toMessage, cell, history, messages, merged },
-        settings  = ConfirmBy[ <| settings0, "HistoryPosition" -> 0, "Cells" -> cells |>, AssociationQ, "Settings" ];
-        role      = makeCurrentRole @ settings;
-        cell      = ConfirmMatch[ Last[ cells, $Failed ], _Cell, "Cell" ];
-        toMessage = Confirm[ getCellMessageFunction @ settings, "CellMessageFunction" ];
-        message   = ConfirmMatch[ toMessage[ cell, settings ], $$validMessageResults, "Message" ];
+makeChatMessages0[ settings0_, cells_List ] := Enclose[
+    Module[ { settings, role, message, toMessage0, toMessage, cell, history, messages, merged },
+        settings   = ConfirmBy[ <| settings0, "HistoryPosition" -> 0, "Cells" -> cells |>, AssociationQ, "Settings" ];
+        role       = makeCurrentRole @ settings;
+        cell       = ConfirmMatch[ Last[ cells, $Failed ], _Cell, "Cell" ];
+        toMessage0 = Confirm[ getCellMessageFunction @ settings, "CellMessageFunction" ];
+
+        $tokenBudgetLog = Internal`Bag[ ];
+        $initialCellStringBudget = Replace[
+            settings[ "MaxCellStringLength" ],
+            Except[ $$size ] -> $defaultMaxCellStringLength
+        ];
+
+        toMessage = Function @ With[
+            { msg = toMessage0[ #1, <| #2, "TokenBudget" -> $tokenBudget, "TokenPressure" -> $tokenPressure |> ] },
+            decreaseTokenBudget[ settings, msg ];
+            msg
+        ];
+
+        message = ConfirmMatch[ toMessage[ cell, settings ], $$validMessageResults, "Message" ];
 
         history = ConfirmMatch[
             Reverse @ Flatten @ MapIndexed[
@@ -210,14 +255,125 @@ makeChatMessages[ settings0_, cells_List ] := Enclose[
             "History"
         ];
 
-        messages = DeleteMissing @ Flatten @ { role, history, message };
-        merged   = If[ TrueQ @ Lookup[ settings, "MergeMessages" ], mergeMessageData @ messages, messages ];
-        merged
+        messages = addExcisedCellMessage @ DeleteMissing @ Flatten @ { role, history, message };
+
+        merged = If[ TrueQ @ Lookup[ settings, "MergeMessages" ], mergeMessageData @ messages, messages ];
+        $lastMessageList = merged
     ],
-    throwInternalFailure[ makeChatMessages[ settings0, cells ], ## ] &
+    throwInternalFailure[ makeChatMessages0[ settings0, cells ], ## ] &
 ];
 
-makeChatMessages // endDefinition;
+makeChatMessages0 // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*addExcisedCellMessage*)
+addExcisedCellMessage // beginDefinition;
+
+addExcisedCellMessage[ messages: { ___Association } ] := Enclose[
+    Module[ { split },
+        split = SplitBy[ messages, MatchQ @ KeyValuePattern[ "Content" -> "[Cell Excised]" ] ];
+        ConfirmMatch[ Flatten[ combineExcisedMessages /@ split ], { ___Association }, "Messages" ]
+    ],
+    throwInternalFailure[ addExcisedCellMessage @ messages, ## ] &
+];
+
+addExcisedCellMessage // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsubsection::Closed:: *)
+(*combineExcisedMessages*)
+combineExcisedMessages // beginDefinition;
+
+combineExcisedMessages[ messages: { msg: KeyValuePattern[ "Content" -> "[Cell Excised]" ], ___ } ] :=
+    <| "Role" -> "System", "Content" -> "[" <> ToString @ Length @ messages <> " Cells Excised]" |>;
+
+combineExcisedMessages[ messages_ ] := messages;
+
+combineExcisedMessages // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*decreaseTokenBudget*)
+decreaseTokenBudget // beginDefinition;
+
+decreaseTokenBudget[ as_Association, message_ ] := Enclose[
+    Module[ { count, budget },
+
+        count  = ConfirmMatch[ tokenCount[ as, message ], $$size, "Count" ];
+        budget = ConfirmMatch[ $tokenBudget, $$size, "Budget" ];
+
+        $tokenBudget      = Max[ 0, budget - count ];
+        $tokenPressure    = 1.0 - ($tokenBudget / as[ "MaxContextTokens" ]);
+        $cellStringBudget = If[ $tokenBudget < $reservedTokens,
+                                0,
+                                Ceiling[ (1 - $tokenPressure) * $initialCellStringBudget ]
+                            ];
+
+        Internal`StuffBag[
+            $tokenBudgetLog,
+            <|
+                "PreviousBudget"   -> budget,
+                "TokenBudget"      -> $tokenBudget,
+                "Pressure"         -> $tokenPressure,
+                "CellStringBudget" -> $cellStringBudget,
+                "MessageTokens"    -> count,
+                "Message"          -> message
+            |>
+        ]
+    ],
+    throwInternalFailure[ decreaseTokenBudget[ as, message ], ## ] &
+];
+
+decreaseTokenBudget // endDefinition;
+
+
+$tokenBudgetLog = Internal`Bag[ ];
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*tokenCount*)
+tokenCount // beginDefinition;
+
+tokenCount[ as_Association, message_ ] := Enclose[
+    Module[ { tokenizer, content },
+        tokenizer = getTokenizer @ as;
+        content = ConfirmBy[ messageContent @ message, validContentQ, "Content" ];
+        Length @ ConfirmMatch[ applyTokenizer[ tokenizer, content ], _List, "TokenCount" ]
+    ],
+    throwInternalFailure[ tokenCount[ as, message ], ## ] &
+];
+
+tokenCount // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*applyTokenizer*)
+applyTokenizer // beginDefinition;
+applyTokenizer[ tokenizer_, content_String ] := tokenizer @ content;
+applyTokenizer[ tokenizer_, content_? graphicsQ ] := tokenizer @ content;
+applyTokenizer[ tokenizer_, content_List ] := Flatten[ tokenizer /@ content ];
+applyTokenizer[ tokenizer_, KeyValuePattern[ "Data" -> data_ ] ] := tokenizer @ data;
+applyTokenizer // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*messageContent*)
+messageContent // beginDefinition;
+
+messageContent[ "[Cell Excised]" ] := "";
+messageContent[ content_String ] := content;
+messageContent[ KeyValuePattern[ "Content" -> content_ ] ] := messageContent @ content;
+messageContent[ KeyValuePattern @ { "Type" -> "Text"|"Image", "Data" -> content_ } ] := messageContent @ content;
+
+messageContent[ content_List ] :=
+    With[ { s = messageContent /@ content },
+        StringRiffle[ s, "\n\n" ] /; AllTrue[ s, StringQ ]
+    ];
+
+messageContent[ content_ ] := content;
+
+messageContent // endDefinition;
 
 (* ::**************************************************************************************************************:: *)
 (* ::Subsection::Closed:: *)
@@ -433,7 +589,7 @@ makeCurrentCellMessage[ settings_, { cells___, cell0_ } ] := Enclose[
     Module[ { modifiers, cell, role, content },
         { modifiers, cell } = ConfirmMatch[ extractModifiers @ cell0, { _, _ }, "Modifiers" ];
         role = ConfirmBy[ cellRole @ cell, StringQ, "CellRole" ];
-        content = ConfirmBy[ Block[ { $CurrentCell = True }, CellToString @ cell ], StringQ, "Content" ];
+        content = ConfirmBy[ Block[ { $CurrentCell = True }, makeMessageContent @ cell ], validContentQ, "Content" ];
         Flatten @ {
             expandModifierMessages[ settings, modifiers, { cells }, cell ],
             <| "Role" -> role, "Content" -> content |>
@@ -444,11 +600,62 @@ makeCurrentCellMessage[ settings_, { cells___, cell0_ } ] := Enclose[
 
 makeCurrentCellMessage // endDefinition;
 
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*makeMessageContent*)
+makeMessageContent // beginDefinition;
+
+makeMessageContent[ cell_Cell ] /; $multimodalMessages := Enclose[
+    Module[ { string, split, joined },
+        string = ConfirmBy[ cellToString @ cell, StringQ, "CellToString" ];
+
+        split = Flatten @ StringSplit[
+            string,
+            md: Shortest[ "MarkdownImageBox[\"" ~~ link: ("![" ~~ __ ~~ "](" ~~ __ ~~ ")") ~~ "\"]" ] :> {
+                md,
+                ConfirmBy[ GetExpressionURI[ link, Tooltip -> False ], ImageQ, "GetExpressionURI" ]
+            }
+        ];
+
+        joined = FixedPoint[ Replace[ { a___, b_String, c_String, d___ } :> { a, b<>c, d } ], split ];
+        Replace[ joined, { msg_String } :> msg ]
+    ],
+    throwInternalFailure[ makeMessageContent @ cell, ## ] &
+];
+
+makeMessageContent[ cell_Cell ] :=
+    cellToString @ cell;
+
+makeMessageContent // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*cellToString*)
+cellToString // beginDefinition;
+cellToString[ cell_Cell ] := CellToString[ cell, "MaxCellStringLength" -> $cellStringBudget ];
+cellToString // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*validContentQ*)
+validContentQ[ string_String ] := StringQ @ string;
+validContentQ[ content_List ] := AllTrue[ content, validContentPartQ ];
+validContentQ[ ___ ] := False;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*validContentPartQ*)
+validContentPartQ[ _String? StringQ ] := True;
+validContentPartQ[ _URL | _File     ] := True;
+validContentPartQ[ _? graphicsQ     ] := True;
+validContentPartQ[ KeyValuePattern[ "Type" -> _String ] ] := True;
+validContentPartQ[ ___ ] := False;
+
 (* ::**************************************************************************************************************:: *)
 (* ::Subsection::Closed:: *)
 (*makeCellMessage*)
 makeCellMessage // beginDefinition;
-makeCellMessage[ cell_Cell ] := <| "Role" -> cellRole @ cell, "Content" -> CellToString @ cell |>;
+makeCellMessage[ cell_Cell ] := <| "Role" -> cellRole @ cell, "Content" -> makeMessageContent @ cell |>;
 makeCellMessage // endDefinition;
 
 (* ::**************************************************************************************************************:: *)
@@ -474,9 +681,19 @@ cellRole // endDefinition;
 (* ::Subsection::Closed:: *)
 (*mergeMessageData*)
 mergeMessageData // beginDefinition;
-mergeMessageData[ messages_ ] := mergeMessages /@ SplitBy[ messages, Lookup[ "Role" ] ];
+
+mergeMessageData[ { sys: KeyValuePattern[ "Role" -> "System" ], rest___ } ] :=
+    Flatten @ { sys, mergeMessageData0 @ { rest } };
+
+mergeMessageData[ messages_List ] :=
+    mergeMessageData0 @ messages;
+
 mergeMessageData // endDefinition;
 
+mergeMessageData0 // beginDefinition;
+mergeMessageData0[ messages_List ] := Flatten[ mergeMessages /@ SplitBy[ messages, Lookup[ "Role" ] ] ];
+mergeMessageData0 // endDefinition;
+
 (* ::**************************************************************************************************************:: *)
 (* ::Subsection::Closed:: *)
 (*mergeMessages*)
@@ -485,13 +702,28 @@ mergeMessages // beginDefinition;
 mergeMessages[ { } ] := Nothing;
 mergeMessages[ { message_ } ] := message;
 mergeMessages[ messages: { first_Association, __Association } ] :=
-    Module[ { role, strings },
-        role    = Lookup[ first   , "Role"    ];
-        strings = Lookup[ messages, "Content" ];
-        <|
-            "Role"    -> role,
-            "Content" -> StringDelete[ StringRiffle[ strings, "\n\n" ], "```\n\n```" ]
-        |>
+    Module[ { role, content, stitch },
+        role    = Lookup[ first, "Role" ];
+        content = Flatten @ Lookup[ messages, "Content" ];
+        stitch  = StringDelete[ #1, "```\n\n```" ] &;
+
+        If[ AllTrue[ content, StringQ ],
+            <|
+                "Role"    -> role,
+                "Content" -> stitch @ StringRiffle[ content, "\n\n" ]
+            |>,
+            <|
+                "Role" -> role,
+                "Content" -> FixedPoint[
+                    Replace @ {
+                        { a___, b_String, c_String, d___ } :> { a, stitch[ b<>"\n\n"<>c ], d },
+                        { a___, b_String, { c_String, d___ }, e___ } :> { a, { stitch[ b<>"\n\n"<>c ], d }, e },
+                        { a___, { b___, c_String }, d_String, e___ } :> { a, { b, stitch[ c<>"\n\n"<>d ] }, e }
+                    },
+                    content
+                ]
+            |>
+        ]
     ];
 
 mergeMessages // endDefinition;
@@ -707,7 +939,7 @@ argumentTokenToString[
             b___
         ]
     }
-] := CellToString @ Cell[ TextData @ { a }, "ChatInput", b ];
+] := cellToString @ Cell[ TextData @ { a }, "ChatInput", b ];
 
 argumentTokenToString[
     ">",
@@ -722,17 +954,125 @@ argumentTokenToString[
     }
 ] := "";
 
-argumentTokenToString[ "^", name_, { ___, cell_, _ } ] := CellToString @ cell;
+argumentTokenToString[ "^", name_, { ___, cell_, _ } ] := cellToString @ cell;
 
-argumentTokenToString[ "^^", name_, { history___, _ } ] := StringRiffle[ CellToString /@ { history }, "\n\n" ];
+argumentTokenToString[ "^^", name_, { history___, _ } ] := StringRiffle[ cellToString /@ { history }, "\n\n" ];
 
 argumentTokenToString // endDefinition;
 
+(* ::**************************************************************************************************************:: *)
+(* ::Section::Closed:: *)
+(*Tokenization*)
+$tokenizer := gpt2Tokenizer;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
+(*getTokenizer*)
+getTokenizer // beginDefinition;
+getTokenizer[ KeyValuePattern[ "Tokenizer" -> tokenizer: Except[ $$unspecified ] ] ] := tokenizer;
+getTokenizer[ KeyValuePattern[ "Model" -> model_ ] ] := getTokenizer @ model;
+getTokenizer[ model_ ] := cachedTokenizer @ toModelName @ model;
+getTokenizer // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*cachedTokenizer*)
+cachedTokenizer // beginDefinition;
+cachedTokenizer[ All ] := AssociationMap[ cachedTokenizer, $cachedTokenizerNames ];
+cachedTokenizer[ name_String ] := cachedTokenizer0 @ tokenizerName @ toModelName @ name;
+cachedTokenizer // endDefinition;
+
+
+cachedTokenizer0 // beginDefinition;
+
+cachedTokenizer0[ "chat-bison" ] = ToCharacterCode[ #, "UTF8" ] &;
+
+cachedTokenizer0[ "gpt-4-vision" ] :=
+    If[ graphicsQ[ # ],
+        gpt4ImageTokenizer[ # ],
+        cachedTokenizer[ "gpt-4" ][ # ]
+    ] &;
+
+cachedTokenizer0[ model_String ] := Enclose[
+    Quiet @ Module[ { name, tokenizer },
+        initTools[ ];
+        Quiet @ Needs[ "Wolfram`LLMFunctions`Utilities`Tokenization`" -> None ];
+        name      = ConfirmBy[ tokens`FindTokenizer @ model, StringQ, "Name" ];
+        tokenizer = ConfirmMatch[ tokens`LLMTokenizer[ Method -> name ], Except[ _tokens`LLMTokenizer ], "Tokenizer" ];
+        ConfirmMatch[ tokenizer[ "test" ], _List, "TokenizerTest" ];
+        cachedTokenizer0[ model ] = tokenizer
+    ],
+    gpt2Tokenizer &
+];
+
+cachedTokenizer0 // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*tokenizerName*)
+tokenizerName // beginDefinition;
+tokenizerName[ name_String ] := SelectFirst[ $cachedTokenizerNames, StringContainsQ[ name, # ] &, name ];
+tokenizerName // endDefinition;
+
+$cachedTokenizerNames = { "gpt-4-vision", "gpt-4", "gpt-3.5", "gpt-2", "claude-2", "claude-instant-1", "chat-bison" };
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
+(*GPT-4 Vision Image Tokenizer *)
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*resizeMultimodalImage*)
+resizeMultimodalImage // beginDefinition;
+
+resizeMultimodalImage[ image0_ ] := Enclose[
+    Module[ { image, dimensions, max, small, resized },
+        image = ConfirmBy[ If[ image2DQ @ image0, image0, Rasterize @ image0 ], image2DQ, "Image" ];
+        dimensions = ConfirmMatch[ ImageDimensions @ image, { _Integer, _Integer }, "Dimensions" ];
+        max = ConfirmMatch[ $maxMMImageSize, _Integer? Positive, "MaxSize" ];
+        small = ConfirmMatch[ AllTrue[ dimensions, LessThan @ max ], True|False, "Small" ];
+        resized = ConfirmBy[ If[ small, image, ImageResize[ image, { UpTo @ max, UpTo @ max } ] ], ImageQ, "Resized" ];
+        resizeMultimodalImage[ image0 ] = resized
+    ],
+    throwInternalFailure[ resizeMultimodalImage @ image0, ## ] &
+];
+
+resizeMultimodalImage // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*gpt4ImageTokenizer*)
+gpt4ImageTokenizer // beginDefinition;
+gpt4ImageTokenizer[ image_ ] := gpt4ImageTokenizer[ image, gpt4ImageTokenCount @ image ];
+gpt4ImageTokenizer[ image_, count: $$size ] := ConstantArray[ 0, count ]; (* TODO: just a placeholder for counting *)
+gpt4ImageTokenizer // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*gpt4ImageTokenCount*)
+gpt4ImageTokenCount // beginDefinition;
+gpt4ImageTokenCount[ image_ ] := gpt4ImageTokenCount[ image, gpt4ImageTokenCount0 @ image ];
+gpt4ImageTokenCount[ image_, count: $$size ] := gpt4ImageTokenCount[ image ] = count;
+gpt4ImageTokenCount // endDefinition;
+
+
+gpt4ImageTokenCount0 // beginDefinition;
+gpt4ImageTokenCount0[ image_ ] := gpt4ImageTokenCount0[ image, resizeMultimodalImage @ image ];
+gpt4ImageTokenCount0[ image_, resized_Image ] := gpt4ImageTokenCount0[ image, ImageDimensions @ resized ];
+gpt4ImageTokenCount0[ image_, { w_, h_ } ] := gpt4ImageTokenCount0[ w, h ];
+gpt4ImageTokenCount0[ w_Integer, h_Integer ] := 85 + 170 * Ceiling[ h / 512 ] * Ceiling[ w / 512 ];
+gpt4ImageTokenCount0 // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
+(*Fallback Tokenizer*)
+gpt2Tokenizer := gpt2Tokenizer = ResourceFunction[ "GPT2Tokenizer" ][ ];
+
 (* ::**************************************************************************************************************:: *)
 (* ::Section::Closed:: *)
 (*Package Footer*)
 If[ Wolfram`ChatbookInternal`$BuildingMX,
-    Null;
+    cachedTokenizer[ All ];
 ];
 
 (* :!CodeAnalysis::EndBlock:: *)
diff --git a/Source/Chatbook/Common.wl b/Source/Chatbook/Common.wl
index 071afce8..954e15f8 100644
--- a/Source/Chatbook/Common.wl
+++ b/Source/Chatbook/Common.wl
@@ -26,6 +26,8 @@ BeginPackage[ "Wolfram`Chatbook`Common`" ];
 `$$excludeHistoryStyle;
 `$$nestedCellStyle;
 
+`$$optionsSequence;
+`$$size;
 `$$textData;
 `$$textDataList;
 `$$unspecified;
@@ -105,6 +107,8 @@ $$nestedCellStyle     = cellStylePattern @ $nestedCellStyles;
 $$textDataItem        = (_String|_Cell|_StyleBox|_ButtonBox);
 $$textDataList        = { $$textDataItem... };
 $$textData            = $$textDataItem | $$textDataList;
+$$optionsSequence     = (Rule|RuleDelayed)[ _Symbol|_String, _ ] ...;
+$$size                = Infinity | (_Real|_Integer)? NonNegative;
 $$unspecified         = _Missing | Automatic | Inherited;
 
 (* ::**************************************************************************************************************:: *)
@@ -117,16 +121,21 @@ KeyValueMap[ Function[ MessageName[ Chatbook, #1 ] = #2 ], <|
     "ConnectionFailure"               -> "Server connection failure: `1`. Please try again later.",
     "ConnectionFailure2"              -> "Could not get a valid response from the server: `1`. Please try again later.",
     "ExpectedInstallableResourceType" -> "Expected a resource of type `1` instead of `2`.",
+    "IntegratedServiceError"          -> "The `1` service returned an error: `2`",
+    "IntegratedServiceUnavailable"    -> "The `1` service is currently not available. Please try again in a few minutes.",
     "Internal"                        -> "An unexpected error occurred. `1`",
     "InvalidAPIKey"                   -> "Invalid value for API key: `1`",
     "InvalidArguments"                -> "Invalid arguments given for `1` in `2`.",
+    "InvalidFrontEndScope"            -> "The value `1` is not a valid scope for `2`.",
     "InvalidFunctions"                -> "Invalid setting for ProcessingFunctions: `1`; using defaults instead.",
+    "InvalidHandlerArguments"         -> "Invalid value for $ChatHandlerData: `1`; resetting to default value.",
     "InvalidHandlerKeys"              -> "Invalid setting for HandlerFunctionsKeys: `1`; using defaults instead.",
     "InvalidHandlers"                 -> "Invalid setting for HandlerFunctions: `1`; using defaults instead.",
-    "InvalidHandlerArguments"         -> "Invalid value for $ChatHandlerData: `1`; resetting to default value.",
-    "InvalidResourceSpecification"    -> "The argument `1` is not a valid resource specification.",
     "InvalidMessages"                 -> "The value `2` returned by `1` is not a valid list of messages.",
+    "InvalidResourceSpecification"    -> "The argument `1` is not a valid resource specification.",
     "InvalidResourceURL"              -> "The specified URL does not represent a valid resource object.",
+    "InvalidRootSettings"             -> "The value `1` is not valid for root chat settings.",
+    "InvalidSettingsKey"              -> "The value `1` is not a valid key for `2`.",
     "InvalidStreamingOutputMethod"    -> "Invalid streaming output method: `1`.",
     "InvalidWriteMethod"              -> "Invalid setting for NotebookWriteMethod: `1`; using default instead.",
     "ModelToolSupport"                -> "The model `1` does not support tools.",
diff --git a/Source/Chatbook/Formatting.wl b/Source/Chatbook/Formatting.wl
index 010551ce..66e043c9 100644
--- a/Source/Chatbook/Formatting.wl
+++ b/Source/Chatbook/Formatting.wl
@@ -606,7 +606,9 @@ $textDataFormatRules = {
     "`" ~~ code: Except[ WhitespaceCharacter ].. ~~ "`" /; inlineSyntaxQ @ code :> inlineCodeCell @ code,
     "`" ~~ code: Except[ "`"|"\n" ].. ~~ "`" :> inlineCodeCell @ code,
     "$$" ~~ math: Except[ "$" ].. ~~ "$$" :> mathCell @ math,
-    "$" ~~ math: Except[ "$" ].. ~~ "$" /; StringFreeQ[ math, "\n" ] :> mathCell @ math
+    "\\(" ~~ math__ ~~ "\\)" /; StringFreeQ[ math, "\\)" ] :> mathCell @ math,
+    "\\[" ~~ math__ ~~ "\\]" /; StringFreeQ[ math, "\\]" ] :> mathCell @ math,
+    "$" ~~ math: Except[ "$" ].. ~~ "$" :> mathCell @ math
 };
 
 (* ::**************************************************************************************************************:: *)
@@ -637,6 +639,8 @@ $dynamicSplitRules = {
 (* ::**************************************************************************************************************:: *)
 (* ::Subsection::Closed:: *)
 (*$stringFormatRules*)
+
+(* cSpell: ignore textit, textbf *)
 $stringFormatRules = {
     "***" ~~ text: Except[ "*" ].. ~~ "***" :> styleBox[ text, FontWeight -> Bold, FontSlant -> Italic ],
     "___" ~~ text: Except[ "_" ].. ~~ "___" :> styleBox[ text, FontWeight -> Bold, FontSlant -> Italic ],
@@ -644,7 +648,9 @@ $stringFormatRules = {
     "__" ~~ text: Except[ "_" ].. ~~ "__" :> styleBox[ text, FontWeight -> Bold ],
     "*" ~~ text: Except[ "*" ].. ~~ "*" :> styleBox[ text, FontSlant -> Italic ],
     "_" ~~ text: Except[ "_" ].. ~~ "_" :> styleBox[ text, FontSlant -> Italic ],
-    "[" ~~ label: Except[ "[" ].. ~~ "](" ~~ url: Except[ ")" ].. ~~ ")" :> hyperlink[ label, url ]
+    "[" ~~ label: Except[ "[" ].. ~~ "](" ~~ url: Except[ ")" ].. ~~ ")" :> hyperlink[ label, url ],
+    "\\textit{" ~~ text__ ~~ "}" /; StringFreeQ[ text, "{"|"}" ] :> styleBox[ text, FontSlant -> Italic ],
+    "\\textbf{" ~~ text__ ~~ "}" /; StringFreeQ[ text, "{"|"}" ] :> styleBox[ text, FontWeight -> Bold ]
 };
 
 (* ::**************************************************************************************************************:: *)
@@ -679,6 +685,13 @@ inlineToolCall[ string_String, as_Association ] := Cell[
     TaggingRules -> KeyDrop[ as, { "Icon", "Result" } ]
 ];
 
+inlineToolCall[ string_String, failed_Failure ] := Cell[
+    BoxData @ ToBoxes @ failed,
+    "FailedToolCall",
+    Background   -> None,
+    TaggingRules -> <| "ToolCall" -> string |>
+];
+
 inlineToolCall // endDefinition;
 
 (* ::**************************************************************************************************************:: *)
@@ -732,6 +745,9 @@ parseFullToolCallString[ id_String, string_String ] :=
 parseFullToolCallString[ id_, _Missing, string_String ] :=
     parsePartialToolCallString @ string;
 
+parseFullToolCallString[ id_, failed_Failure, string_String ] :=
+    failed;
+
 parseFullToolCallString[ id_String, resp: HoldPattern[ _LLMToolResponse ], string_String ] :=
     parseFullToolCallString[
         id,
diff --git a/Source/Chatbook/FrontEnd.wl b/Source/Chatbook/FrontEnd.wl
index 605f3c59..f70d3950 100644
--- a/Source/Chatbook/FrontEnd.wl
+++ b/Source/Chatbook/FrontEnd.wl
@@ -599,12 +599,14 @@ openerView0[ { a_, b_ }, args___ ] /; ByteCount @ b > 50000 := openerView1[ { a,
 openerView0[ { a_, b_ }, args___ ] := openerView1[ { a, b }, args ];
 openerView0 // endDefinition;
 
-
-openerView1[ args___ ] :=
+(*cspell: ignore patv *)
+openerView1[ args___ ] := Quiet[
     RawBoxes @ ReplaceAll[
         Replace[ ToBoxes @ OpenerView @ args, TagBox[ boxes_, ___ ] :> boxes ],
         InterpretationBox[ boxes_, _OpenerView, ___ ] :> boxes
-    ];
+    ],
+    Pattern::patv
+];
 
 (* ::**************************************************************************************************************:: *)
 (* ::Subsection::Closed:: *)
diff --git a/Source/Chatbook/Models.wl b/Source/Chatbook/Models.wl
index 40d38403..d1a38e7e 100644
--- a/Source/Chatbook/Models.wl
+++ b/Source/Chatbook/Models.wl
@@ -9,6 +9,7 @@ BeginPackage[ "Wolfram`Chatbook`Models`" ];
 `chatModelQ;
 `getModelList;
 `modelDisplayName;
+`multimodalModelQ;
 `snapshotModelQ;
 `standardizeModelData;
 `toModelName;
@@ -138,6 +139,9 @@ modelName // endDefinition;
 (*toModelName*)
 toModelName // beginDefinition;
 
+toModelName[ KeyValuePattern @ { "Service" -> service_, "Model" -> model_ } ] :=
+    toModelName @ { service, model };
+
 toModelName[ { service_String, name_String } ] := toModelName @ name;
 
 toModelName[ name_String? StringQ ] := toModelName[ name ] =
@@ -163,17 +167,35 @@ toModelName0 // endDefinition;
 (* ::Subsection::Closed:: *)
 (*snapshotModelQ*)
 snapshotModelQ // beginDefinition;
-snapshotModelQ[ name_String? fineTunedModelQ ] := snapshotModelQ @ StringSplit[ name, ":" ][[ 2 ]];
-snapshotModelQ[ name_String ] := StringMatchQ[ name, "gpt-"~~__~~"-"~~Repeated[ DigitCharacter, { 4 } ] ];
+
+snapshotModelQ[ name_String? fineTunedModelQ ] := snapshotModelQ[ name ] =
+    snapshotModelQ @ StringSplit[ name, ":" ][[ 2 ]];
+
+snapshotModelQ[ name_String? StringQ ] := snapshotModelQ[ name ] =
+    StringMatchQ[ toModelName @ name, "gpt-"~~__~~"-"~~Repeated[ DigitCharacter, { 4 } ]~~(""|"-preview") ];
+
+snapshotModelQ[ other_ ] :=
+    With[ { name = toModelName @ other }, snapshotModelQ @ name /; StringQ @ name ];
+
 snapshotModelQ // endDefinition;
 
 (* ::**************************************************************************************************************:: *)
 (* ::Subsection::Closed:: *)
 (*fineTunedModelQ*)
 fineTunedModelQ // beginDefinition;
-fineTunedModelQ[ name_String ] := StringMatchQ[ name, "ft:"~~__~~":"~~__ ];
+fineTunedModelQ[ name_String ] := StringMatchQ[ toModelName @ name, "ft:"~~__~~":"~~__ ];
+fineTunedModelQ[ other_ ] := With[ { name = toModelName @ other }, fineTunedModelQ @ name /; StringQ @ name ];
 fineTunedModelQ // endDefinition;
 
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
+(*multimodalModelQ*)
+(* FIXME: this should be a queryable property from LLMServices: *)
+multimodalModelQ // beginDefinition;
+multimodalModelQ[ name_String? StringQ ] := StringContainsQ[ toModelName @ name, "gpt-"~~$$modelVersion~~"-vision" ];
+multimodalModelQ[ other_ ] := With[ { name = toModelName @ other }, multimodalModelQ @ name /; StringQ @ name ];
+multimodalModelQ // endDefinition;
+
 (* ::**************************************************************************************************************:: *)
 (* ::Subsection::Closed:: *)
 (*modelDisplayName*)
@@ -200,6 +222,9 @@ modelDisplayName[ { "gpt", rest___ } ] :=
 modelDisplayName[ { before__, date_String } ] /; StringMatchQ[ date, Repeated[ DigitCharacter, { 4 } ] ] :=
     modelDisplayName @ { before, DateObject @ Flatten @ { 0, ToExpression @ StringPartition[ date, 2 ] } };
 
+modelDisplayName[ { before__, "preview" } ] :=
+    modelDisplayName @ { before } <> " (Preview)";
+
 modelDisplayName[ { before___, date_DateObject } ] :=
     modelDisplayName @ {
 		before,
diff --git a/Source/Chatbook/Personas.wl b/Source/Chatbook/Personas.wl
index 5bfe4925..167f1034 100644
--- a/Source/Chatbook/Personas.wl
+++ b/Source/Chatbook/Personas.wl
@@ -32,6 +32,7 @@ Needs[ "Wolfram`Chatbook`"                   ];
 Needs[ "Wolfram`Chatbook`Errors`"            ];
 Needs[ "Wolfram`Chatbook`ErrorUtils`"        ];
 Needs[ "Wolfram`Chatbook`ResourceInstaller`" ];
+Needs[ "Wolfram`Chatbook`Utils`"             ];
 
 (*========================================================*)
 
@@ -213,12 +214,12 @@ loadPersonaFromDirectory[paclet_PacletObject, personaName_, dir_?StringQ] := Mod
 	config = FileNameJoin[{dir, "LLMConfiguration.wl"}];
 
 	pre = If[FileType[pre] === File,
-		readPromptString[pre],
+		readString[pre],
 		Missing["NotAvailable", pre]
 	];
 
 	post = If[FileType[post] === File,
-		readPromptString[post],
+		readString[post],
 		Missing["NotAvailable", post]
 	];
 
@@ -251,8 +252,6 @@ loadPersonaFromDirectory[paclet_PacletObject, personaName_, dir_?StringQ] := Mod
 	]
 ]
 
-readPromptString[ file_ ] := StringReplace[ ByteArrayToString @ ReadByteArray @ file, "\r\n" -> "\n" ];
-
 
 standardizePersonaData // beginDefinition;
 
diff --git a/Source/Chatbook/Prompting.wl b/Source/Chatbook/Prompting.wl
index c1188bac..b1792c0d 100644
--- a/Source/Chatbook/Prompting.wl
+++ b/Source/Chatbook/Prompting.wl
@@ -2,9 +2,9 @@
 (*Package Header*)
 BeginPackage[ "Wolfram`Chatbook`Prompting`" ];
 
-(* TODO: select portions of base prompt during serialization as needed *)
 `$basePrompt;
 `$basePromptComponents;
+`$fullBasePrompt;
 `needsBasePrompt;
 `withBasePromptBuilder;
 
@@ -31,6 +31,7 @@ $basePromptOrder = {
     "MessageConversionHeader",
     "ConversionLargeOutputs",
     "ConversionGraphics",
+    "MarkdownImageBox",
     "ConversionFormatting",
     "VisibleUserInput",
     "TrivialCode",
@@ -65,6 +66,7 @@ $basePromptDependencies = Append[ "GeneralInstructionsHeader" ] /@ <|
     "MessageConversionHeader"      -> { "NotebooksPreamble" },
     "ConversionLargeOutputs"       -> { "MessageConversionHeader" },
     "ConversionGraphics"           -> { "MessageConversionHeader" },
+    "MarkdownImageBox"             -> { "MessageConversionHeader" },
     "ConversionFormatting"         -> { "MessageConversionHeader" },
     "VisibleUserInput"             -> { },
     "TrivialCode"                  -> { },
@@ -111,10 +113,10 @@ $basePromptComponents[ "DoubleBackticks" ] = "\
 * ALWAYS surround inline code with double backticks to avoid ambiguity with context names: ``MyContext`MyFunction[x]``";
 
 $basePromptComponents[ "MathExpressions" ] = "\
-* Write math expressions using LaTeX and surround them with dollar signs: $x^2 + y^2$";
+* Write math expressions using LaTeX and surround them with dollar signs: $$x^2 + y^2$$";
 
 $basePromptComponents[ "EscapedCharacters" ] = "\
-* IMPORTANT! Whenever you write a literal backtick or dollar sign in text, ALWAYS escape it with a backslash. \
+* IMPORTANT! Whenever you write a literal backtick (`) or dollar sign ($) in text, ALWAYS escape it with a backslash. \
 Example: It costs me \\$99.95 every time you forget to escape \\` or \\$ properly!";
 
 $basePromptComponents[ "DocumentationLinkSyntax" ] = "\
@@ -136,11 +138,15 @@ $basePromptComponents[ "ConversionLargeOutputs" ] = "\
 $basePromptComponents[ "ConversionGraphics" ] = "\
 	* Rendered graphics will typically be replaced with a shortened box representation: \\!\\(\\*GraphicsBox[<<>>]\\)";
 
+$basePromptComponents[ "MarkdownImageBox" ] = "\
+	* If there are images embedded in the notebook, they will be replaced by a box representation in the \
+form ``MarkdownImageBox[\"![label](uri)\"]``. You will also receive the original image immediately after this. \
+You can use the markdown from this box ``![label](uri)`` in your responses if you want to display the original image.";
+
 $basePromptComponents[ "ConversionFormatting" ] = "\
 	* Cell formatting is removed when converting to text, so \
 ``Cell[TextData[{StyleBox[\"Styled\", FontSlant -> \"Italic\"], \" message\"}], \"ChatInput\"]`` \
-becomes \
-``Styled message``.";
+becomes ``Styled message``.";
 
 $basePromptComponents[ "VisibleUserInput" ] = "\
 * The user can still see their input, so there's no need to repeat it in your response";
@@ -260,8 +266,10 @@ $collectedPromptComponents = AssociationMap[
     Keys @ Association[ KeyTake[ $basePromptComponents, $basePromptOrder ], $basePromptComponents ]
 ];
 
+$fullBasePrompt = $basePrompt;
+
 If[ Wolfram`ChatbookInternal`$BuildingMX,
-    Null
+    Null;
 ];
 
 End[ ];
diff --git a/Source/Chatbook/Sandbox.wl b/Source/Chatbook/Sandbox.wl
index fe7700e9..369a7845 100644
--- a/Source/Chatbook/Sandbox.wl
+++ b/Source/Chatbook/Sandbox.wl
@@ -566,48 +566,6 @@ sandboxFormatter[ result_, ___ ] := result;
 
 sandboxFormatter // endDefinition;
 
-(* ::**************************************************************************************************************:: *)
-(* ::Section::Closed:: *)
-(*Misc*)
-
-(* ::**************************************************************************************************************:: *)
-(* ::Subsection::Closed:: *)
-(*Graphics Utilities*)
-
-$$graphics = HoldPattern[ _GeoGraphics | _Graphics | _Graphics3D | _Image | _Image3D | _Legended ];
-
-(* ::**************************************************************************************************************:: *)
-(* ::Subsubsection::Closed:: *)
-(*graphicsQ*)
-graphicsQ[ $$graphics ] := True;
-graphicsQ[ g_         ] := MatchQ[ Quiet @ Show @ Unevaluated @ g, $$graphics ];
-graphicsQ[ ___        ] := False;
-
-(* ::**************************************************************************************************************:: *)
-(* ::Subsubsection::Closed:: *)
-(*validGraphicsQ*)
-validGraphicsQ[ g_? graphicsQ ] := getGraphicsErrors @ Unevaluated @ g === { };
-validGraphicsQ[ ___ ] := False;
-
-(* ::**************************************************************************************************************:: *)
-(* ::Subsubsection::Closed:: *)
-(*getGraphicsErrors*)
-getGraphicsErrors // beginDefinition;
-
-(* TODO: hook this up to outputs to give feedback about pink boxes *)
-getGraphicsErrors[ gfx_ ] :=
-    Module[ { cell, nbo },
-        cell = Cell @ BoxData @ MakeBoxes @ gfx;
-        UsingFrontEnd @ WithCleanup[
-            nbo = NotebookPut[ Notebook @ { cell }, Visible -> False ],
-            SelectionMove[ First @ Cells @ nbo, All, Cell ];
-            MathLink`CallFrontEnd @ FrontEnd`GetErrorsInSelectionPacket @ nbo,
-            NotebookClose @ nbo
-        ]
-    ];
-
-getGraphicsErrors // endDefinition;
-
 (* ::**************************************************************************************************************:: *)
 (* ::Section::Closed:: *)
 (*Package Footer*)
diff --git a/Source/Chatbook/SendChat.wl b/Source/Chatbook/SendChat.wl
index a87fe3f9..b9842951 100644
--- a/Source/Chatbook/SendChat.wl
+++ b/Source/Chatbook/SendChat.wl
@@ -2,6 +2,8 @@
 (*Package Header*)
 BeginPackage[ "Wolfram`Chatbook`SendChat`" ];
 
+(* cSpell: ignore evaliator *)
+
 (* :!CodeAnalysis::BeginBlock:: *)
 
 `$debugLog;
@@ -24,6 +26,7 @@ Needs[ "Wolfram`Chatbook`Handlers`"         ];
 Needs[ "Wolfram`Chatbook`InlineReferences`" ];
 Needs[ "Wolfram`Chatbook`Models`"           ];
 Needs[ "Wolfram`Chatbook`Personas`"         ];
+Needs[ "Wolfram`Chatbook`Serialization`"    ];
 Needs[ "Wolfram`Chatbook`Services`"         ];
 Needs[ "Wolfram`Chatbook`Settings`"         ];
 Needs[ "Wolfram`Chatbook`Tools`"            ];
@@ -306,12 +309,12 @@ makeHTTPRequest[ settings_Association? AssociationQ, messages: { __Association }
         stream      = True;
 
         (* model parameters *)
-        model       = Lookup[ settings, "Model"           , "gpt-3.5-turbo" ];
-        tokens      = Lookup[ settings, "MaxTokens"       , Automatic       ];
-        temperature = Lookup[ settings, "Temperature"     , 0.7             ];
-        topP        = Lookup[ settings, "TopP"            , 1               ];
-        freqPenalty = Lookup[ settings, "FrequencyPenalty", 0.1             ];
-        presPenalty = Lookup[ settings, "PresencePenalty" , 0.1             ];
+        model       = Lookup[ settings, "Model"           , $DefaultModel ];
+        tokens      = Lookup[ settings, "MaxTokens"       , Automatic     ];
+        temperature = Lookup[ settings, "Temperature"     , 0.7           ];
+        topP        = Lookup[ settings, "TopP"            , 1             ];
+        freqPenalty = Lookup[ settings, "FrequencyPenalty", 0.1           ];
+        presPenalty = Lookup[ settings, "PresencePenalty" , 0.1           ];
 
         data = DeleteCases[
             <|
@@ -330,6 +333,7 @@ makeHTTPRequest[ settings_Association? AssociationQ, messages: { __Association }
 
         body = ConfirmBy[ Developer`WriteRawJSONString[ data, "Compact" -> True ], StringQ ];
 
+        $lastHTTPParameters = data;
         $lastRequest = HTTPRequest[
             "https://api.openai.com/v1/chat/completions",
             <|
@@ -349,19 +353,128 @@ makeHTTPRequest // endDefinition;
 (* ::Subsubsection::Closed:: *)
 (*prepareMessagesForHTTPRequest*)
 prepareMessagesForHTTPRequest // beginDefinition;
-prepareMessagesForHTTPRequest[ message_Association ] := prepareMessagesForHTTPRequest0 @ KeyMap[ ToLowerCase, message ];
-prepareMessagesForHTTPRequest[ messages_List ] := prepareMessagesForHTTPRequest /@ messages;
+prepareMessagesForHTTPRequest[ messages_List ] := $lastHTTPMessages = prepareMessageForHTTPRequest /@ messages;
 prepareMessagesForHTTPRequest // endDefinition;
 
-prepareMessagesForHTTPRequest0 // beginDefinition;
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*prepareMessageForHTTPRequest*)
+prepareMessageForHTTPRequest // beginDefinition;
+prepareMessageForHTTPRequest[ message_Association? AssociationQ ] := AssociationMap[ prepareMessageRule, message ];
+prepareMessageForHTTPRequest // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*prepareMessageRule*)
+prepareMessageRule // beginDefinition;
+prepareMessageRule[ "Role"|"role"       -> role_String ] := "role"    -> ToLowerCase @ role;
+prepareMessageRule[ "Content"|"content" -> content_    ] := "content" -> prepareMessageContent @ content;
+prepareMessageRule[ key_String          -> value_      ] := ToLowerCase @ key -> value;
+prepareMessageRule // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*prepareMessageContent*)
+prepareMessageContent // beginDefinition;
+prepareMessageContent[ content_String ] := content;
+prepareMessageContent[ content_List   ] := prepareMessagePart /@ content;
+prepareMessageContent // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*prepareMessagePart*)
+prepareMessagePart // beginDefinition;
+prepareMessagePart[ text_String         ] := prepareMessagePart @ <| "Type" -> "Text" , "Data" -> text  |>;
+prepareMessagePart[ image_? graphicsQ   ] := prepareMessagePart @ <| "Type" -> "Image", "Data" -> image |>;
+prepareMessagePart[ file_File           ] := prepareMessagePart @ <| "Type" -> partType @ file, "Data" -> file |>;
+prepareMessagePart[ url_URL             ] := prepareMessagePart @ <| "Type" -> partType @ url , "Data" -> url  |>;
+prepareMessagePart[ part_? AssociationQ ] := prepareMessagePart0 @ KeyMap[ ToLowerCase, part ];
+prepareMessagePart // endDefinition;
+
+prepareMessagePart0 // beginDefinition;
+
+prepareMessagePart0[ part_Association ] := <|
+    KeyDrop[ part, "data" ],
+    prepareMessagePart0[ part[ "type" ], part[ "data" ] ]
+|>;
+
+prepareMessagePart0[ "Text" , text_   ] := <| "type" -> "text"     , "text"      -> prepareTextPart @ text    |>;
+prepareMessagePart0[ "Image", img_    ] := <| "type" -> "image_url", "image_url" -> prepareImageURLPart @ img |>;
+prepareMessagePart0 // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*prepareImageURLPart*)
+prepareImageURLPart // beginDefinition;
+prepareImageURLPart[ URL[ url_String ] ] := <| "url" -> url |>;
+prepareImageURLPart[ file_File ] := With[ { img = importImage @ file }, prepareImageURLPart @ img /; graphicsQ @ img ];
+prepareImageURLPart[ image_ ] := prepareImageURLPart @ URL @ toDataURI @ image;
+prepareImageURLPart // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsubsection::Closed:: *)
+(*importImage*)
+importImage // beginDefinition;
+importImage[ file_File ] := importImage[ file, fastFileHash @ file ];
+importImage[ file_, hash_Integer ] := With[ { img = $importImageCache[ file, hash ] }, img /; image2DQ @ img ];
+importImage[ file_, hash_Integer ] := $importImageCache[ file ] = <| hash -> importImage0 @ file |>;
+importImage // endDefinition;
+
+$importImageCache = <| |>;
+
+importImage0 // beginDefinition;
+importImage0[ file_ ] := importImage0[ file, Import[ file, "Image" ] ];
+importImage0[ file_, img_? graphicsQ ] := img;
+importImage0 // endDefinition;
 
-prepareMessagesForHTTPRequest0[ message: KeyValuePattern[ "role" -> role_String ] ] :=
-    Insert[ message, "role" -> ToLowerCase @ role, Key[ "role" ] ];
+(* TODO: if an "ExternalFile" type of chat cell is defined, this should throw appropriate error text here *)
 
-prepareMessagesForHTTPRequest0[ message_Association ] :=
-    message;
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*prepareTextPart*)
+prepareTextPart // beginDefinition;
+prepareTextPart[ text_String? StringQ   ] := text;
+prepareTextPart[ file_File? FileExistsQ ] := prepareTextPart @ readString @ file;
+prepareTextPart[ url_URL                ] := prepareTextPart @ URLRead[ url, "Body" ];
+prepareTextPart[ failure_Failure        ] := makeFailureString @ failure;
+prepareTextPart // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*partType*)
+partType // beginDefinition;
+partType[ url_URL   ] := "Image"; (* this could determine type automatically, but it would likely be too slow *)
+partType[ file_File ] := partType[ file, fastFileHash @ file ];
+partType[ file_, hash_Integer ] := With[ { type = $partTypeCache[ file, hash ] }, type /; StringQ @ type ];
+partType[ file_, hash_Integer ] := With[ { t = partType0 @ file }, $partTypeCache[ file ] = <| hash -> t |>; t ];
+partType // endDefinition;
+
+$partTypeCache = <| |>;
+
+partType0 // beginDefinition;
+partType0[ file_ ] := partType0[ file, FileFormat @ file ];
+partType0[ file_, fmt_String ] := partType0[ file, fmt, FileFormatProperties[ fmt, "ImportElements" ] ];
+partType0[ file_, fmt_, { ___, "Image", ___ } ] := "Image";
+partType0[ file_, fmt_, _List ] := "Text";
+partType0 // endDefinition;
+
+(* TODO: if an "ExternalFile" type of chat cell is defined, this should throw appropriate error text here *)
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*toDataURI*)
+toDataURI // beginDefinition;
+
+toDataURI[ image_ ] := Enclose[
+    Module[ { resized, base64 },
+        resized = ConfirmBy[ resizeMultimodalImage @ image, image2DQ, "Resized" ];
+        base64 = ConfirmBy[ ExportString[ resized, { "Base64", "PNG" } ], StringQ, "Base64" ];
+        toDataURI[ image ] = "data:image/png;base64," <> StringDelete[ base64, "\n" ]
+    ],
+    throwInternalFailure[ toDataURI @ image, ## ] &
+];
 
-prepareMessagesForHTTPRequest0 // endDefinition;
+toDataURI // endDefinition;
 
 (* ::**************************************************************************************************************:: *)
 (* ::Subsection::Closed:: *)
@@ -451,7 +564,7 @@ ServiceConnectionUtilities`ConnectionInformation["Anthropic", "ProcessedRequests
 
 makeLLMConfiguration[ as_Association ] :=
     $lastLLMConfiguration = LLMConfiguration @ Association[
-        KeyTake[ as, { "Model" } ],
+        KeyTake[ as, { "Model", "MaxTokens" } ],
         "StopTokens" -> { "ENDTOOLCALL" }
     ];
 
@@ -649,12 +762,24 @@ appendStringContent // Attributes = { HoldFirst };
 
 appendStringContent[ container_, text_String ] :=
     If[ StringQ @ container,
-        container = StringDelete[ container <> convertUTF8 @ text, StartOfString~~Whitespace ],
-        container = convertUTF8 @ text
+        container = autoCorrect @ StringDelete[ container <> convertUTF8 @ text, StartOfString~~Whitespace ],
+        container = autoCorrect @ convertUTF8 @ text
     ];
 
 appendStringContent // endDefinition;
 
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*autoCorrect*)
+autoCorrect // beginDefinition;
+autoCorrect[ string_String ] := StringReplace[ string, $llmAutoCorrectRules ];
+autoCorrect // endDefinition;
+
+$llmAutoCorrectRules = {
+    "wolfram_language_evaliator" -> "wolfram_language_evaluator",
+    "\\!\\(\\*MarkdownImageBox[\"" ~~ uri__ ~~ "\"]\\)" :> uri
+};
+
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsection::Closed:: *)
 (*splitDynamicContent*)
@@ -1057,12 +1182,8 @@ resolveAutoSettings // beginDefinition;
 resolveAutoSettings[ settings: KeyValuePattern[ _ :> _ ] ] :=
     resolveAutoSettings @ AssociationMap[ Apply @ Rule, settings ];
 
-(* Determine if tools are actually enabled based on settings *)
-resolveAutoSettings[ settings: KeyValuePattern[ "ToolsEnabled" -> Automatic ] ] :=
-    resolveAutoSettings @ Association[ settings, "ToolsEnabled" -> toolsEnabledQ @ settings ];
-
 (* Add additional settings and resolve actual LLMTool expressions *)
-resolveAutoSettings[ settings_Association ] := resolveTools @ <|
+resolveAutoSettings[ settings_Association ] := resolveAutoSettings0 @ <|
     settings,
     "HandlerFunctions"    -> getHandlerFunctions @ settings,
     "LLMEvaluator"        -> getLLMEvaluator @ settings,
@@ -1071,7 +1192,157 @@ resolveAutoSettings[ settings_Association ] := resolveTools @ <|
 
 resolveAutoSettings // endDefinition;
 
-(* TODO: define singular `resolveAutoSetting` that expands each `Automatic` value *)
+
+resolveAutoSettings0 // beginDefinition;
+
+resolveAutoSettings0[ settings_Association ] := Enclose[
+    Module[ { auto, sorted, resolved },
+        auto     = ConfirmBy[ Select[ settings, SameAs @ Automatic ], AssociationQ, "Auto" ];
+        sorted   = ConfirmBy[ <| KeyTake[ auto, $autoSettingKeyPriority ], auto |>, AssociationQ, "Sorted" ];
+        resolved = ConfirmBy[ Fold[ resolveAutoSetting, settings, Normal @ sorted ], AssociationQ, "Resolved" ];
+        ConfirmBy[ resolveTools @ KeySort @ resolved, AssociationQ, "ResolveTools" ]
+    ],
+    throwInternalFailure[ resolveAutoSettings0 @ settings, ## ] &
+];
+
+resolveAutoSettings0 // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*resolveAutoSetting*)
+resolveAutoSetting // beginDefinition;
+resolveAutoSetting[ settings_, key_ -> value_ ] := <| settings, key -> resolveAutoSetting0[ settings, key ] |>;
+resolveAutoSetting // endDefinition;
+
+resolveAutoSetting0 // beginDefinition;
+resolveAutoSetting0[ as_, "ToolsEnabled"              ] := toolsEnabledQ @ as;
+resolveAutoSetting0[ as_, "DynamicAutoFormat"         ] := dynamicAutoFormatQ @ as;
+resolveAutoSetting0[ as_, "EnableLLMServices"         ] := $useLLMServices;
+resolveAutoSetting0[ as_, "HandlerFunctionsKeys"      ] := chatHandlerFunctionsKeys @ as;
+resolveAutoSetting0[ as_, "IncludeHistory"            ] := Automatic;
+resolveAutoSetting0[ as_, "NotebookWriteMethod"       ] := "PreemptiveLink";
+resolveAutoSetting0[ as_, "ShowMinimized"             ] := Automatic;
+resolveAutoSetting0[ as_, "StreamingOutputMethod"     ] := "PartialDynamic";
+resolveAutoSetting0[ as_, "TrackScrollingWhenPlaced"  ] := scrollOutputQ @ as;
+resolveAutoSetting0[ as_, "Multimodal"                ] := multimodalQ @ as;
+resolveAutoSetting0[ as_, "MaxContextTokens"          ] := autoMaxContextTokens @ as;
+resolveAutoSetting0[ as_, "MaxTokens"                 ] := autoMaxTokens @ as;
+resolveAutoSetting0[ as_, "MaxCellStringLength"       ] := chooseMaxCellStringLength @ as;
+resolveAutoSetting0[ as_, "MaxOutputCellStringLength" ] := chooseMaxOutputCellStringLength @ as;
+resolveAutoSetting0[ as_, "Tokenizer"                 ] := getTokenizer @ as;
+resolveAutoSetting0[ as_, key_String                  ] := Automatic;
+resolveAutoSetting0 // endDefinition;
+
+(* Settings that require other settings to be resolved first: *)
+$autoSettingKeyDependencies = <|
+    "HandlerFunctionsKeys"      -> "EnableLLMServices",
+    "MaxCellStringLength"       -> { "Model", "MaxContextTokens" },
+    "MaxContextTokens"          -> "Model",
+    "MaxOutputCellStringLength" -> "MaxCellStringLength",
+    "MaxTokens"                 -> "Model",
+    "Multimodal"                -> { "EnableLLMServices", "Model" },
+    "Tokenizer"                 -> "Model",
+    "Tools"                     -> { "LLMEvaluator", "ToolsEnabled" },
+    "ToolsEnabled"              -> "Model"
+|>;
+
+(* Sort topologically so dependencies will be satisfied in order: *)
+$autoSettingKeyPriority := Enclose[
+    $autoSettingKeyPriority = ConfirmMatch[
+        TopologicalSort @ Flatten @ KeyValueMap[
+            Thread @* Reverse @* Rule,
+            $autoSettingKeyDependencies
+        ],
+        { __String? StringQ }
+    ],
+    throwInternalFailure[ $autoSettingKeyPriority, ## ] &
+];
+
+(* TODO: resolve these automatic values here:
+    * BasePrompt (might not be possible here)
+    * ChatContextPreprompt
+*)
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*chooseMaxCellStringLength*)
+(* FIXME: need to hook into token pressure to gradually decrease limits *)
+chooseMaxCellStringLength // beginDefinition;
+chooseMaxCellStringLength[ as_Association ] := chooseMaxCellStringLength[ as, as[ "MaxContextTokens" ] ];
+chooseMaxCellStringLength[ as_, tokens: $$size ] := Ceiling[ $defaultMaxCellStringLength * tokens / 2^13 ];
+chooseMaxCellStringLength // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*chooseMaxOutputCellStringLength*)
+chooseMaxOutputCellStringLength // beginDefinition;
+chooseMaxOutputCellStringLength[ as_Association ] := chooseMaxOutputCellStringLength[ as, as[ "MaxCellStringLength" ] ];
+chooseMaxOutputCellStringLength[ as_, size: $$size ] := Min[ Ceiling[ size / 10 ], 1000 ];
+chooseMaxOutputCellStringLength // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*autoMaxContextTokens*)
+autoMaxContextTokens // beginDefinition;
+autoMaxContextTokens[ as_Association ] := autoMaxContextTokens[ as, as[ "Model" ] ];
+autoMaxContextTokens[ as_, model_ ] := autoMaxContextTokens[ as, model, toModelName @ model ];
+autoMaxContextTokens[ _, _, name_String ] := autoMaxContextTokens0 @ name;
+autoMaxContextTokens // endDefinition;
+
+autoMaxContextTokens0 // beginDefinition;
+autoMaxContextTokens0[ name_String ] := autoMaxContextTokens0 @ StringSplit[ name, "-"|Whitespace ];
+autoMaxContextTokens0[ { ___, "gpt", "4", "vision", ___ } ] := 2^17;
+autoMaxContextTokens0[ { ___, "gpt", "4", "turbo" , ___ } ] := 2^17;
+autoMaxContextTokens0[ { ___, "claude", "2"       , ___ } ] := 10^5;
+autoMaxContextTokens0[ { ___, "16k"               , ___ } ] := 2^14;
+autoMaxContextTokens0[ { ___, "32k"               , ___ } ] := 2^15;
+autoMaxContextTokens0[ { ___, "gpt", "4"          , ___ } ] := 2^13;
+autoMaxContextTokens0[ { ___, "gpt", "3.5"        , ___ } ] := 2^12;
+autoMaxContextTokens0[ _List                              ] := 2^12;
+autoMaxContextTokens0 // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*autoMaxTokens*)
+autoMaxTokens // beginDefinition;
+autoMaxTokens[ as_Association ] := autoMaxTokens[ as, as[ "Model" ] ];
+autoMaxTokens[ as_, model_ ] := autoMaxTokens[ as, model, toModelName @ model ];
+autoMaxTokens[ as_, model_, name_String ] := Lookup[ $maxTokensTable, name, Automatic ];
+autoMaxTokens // endDefinition;
+
+(* FIXME: this should be something queryable from LLMServices: *)
+$maxTokensTable = <|
+    "gpt-4-vision-preview" -> 4096,
+    "gpt-4-1106-preview"   -> 4096
+|>;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*multimodalQ*)
+multimodalQ // beginDefinition;
+multimodalQ[ as_Association ] := multimodalQ[ as, multimodalModelQ @ as[ "Model" ], as[ "EnableLLMServices" ] ];
+multimodalQ[ as_, True , False ] := True;
+multimodalQ[ as_, True , True  ] := multimodalPacletsAvailable[ ];
+multimodalQ[ as_, False, _     ] := False;
+multimodalQ // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsubsection::Closed:: *)
+(*$multimodalPacletsAvailable*)
+multimodalPacletsAvailable // beginDefinition;
+
+multimodalPacletsAvailable[ ] := multimodalPacletsAvailable[ ] = (
+    initTools[ ];
+    multimodalPacletsAvailable[
+        PacletObject[ "Wolfram/LLMFunctions"     ],
+        PacletObject[ "ServiceConnection_OpenAI" ]
+    ]
+);
+
+multimodalPacletsAvailable[ llmFunctions_PacletObject? PacletObjectQ, openAI_PacletObject? PacletObjectQ ] :=
+    TrueQ @ And[ PacletNewerQ[ llmFunctions, "1.2.4" ], PacletNewerQ[ openAI, "13.3.18" ] ];
+
+multimodalPacletsAvailable // endDefinition;
 
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsection::Closed:: *)
@@ -1650,7 +1921,9 @@ writeReformattedCell[ settings_, string_String, cell_CellObject ] := Enclose[
 
             With[ { new = new, info = info },
                 createTask @ applyProcessingFunction[ settings, "WriteChatOutputCell", HoldComplete[ cell, new, info ] ]
-            ]
+            ];
+
+            waitForCellObject[ settings, output ]
         ]
     ],
     throwInternalFailure[ writeReformattedCell[ settings, string, cell ], ## ] &
@@ -1675,6 +1948,19 @@ writeReformattedCell[ settings_, other_, cell_CellObject ] :=
 
 writeReformattedCell // endDefinition;
 
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*waitForCellObject*)
+waitForCellObject // beginDefinition;
+
+waitForCellObject[ settings_, cell_CellObject, timeout_: 1 ] :=
+    If[ settings[ "HandlerFunctions", "ChatPost" ] =!= None,
+        TimeConstrained[ While[ ! StringQ @ CurrentValue[ cell, ExpressionUUID ], Pause[ 0.05 ] ], timeout ];
+        cell
+    ];
+
+waitForCellObject // endDefinition;
+
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsubsection::Closed:: *)
 (*scrollOutputQ*)
@@ -2096,7 +2382,7 @@ errorBoxes[ as___ ] :=
 (* ::Section::Closed:: *)
 (*Package Footer*)
 If[ Wolfram`ChatbookInternal`$BuildingMX,
-    Null;
+    $autoSettingKeyPriority;
 ];
 
 (* :!CodeAnalysis::EndBlock:: *)
diff --git a/Source/Chatbook/Serialization.wl b/Source/Chatbook/Serialization.wl
index cfa9bf9c..4955516a 100644
--- a/Source/Chatbook/Serialization.wl
+++ b/Source/Chatbook/Serialization.wl
@@ -11,16 +11,23 @@ CellToString[cell$] serializes a Cell expression as a string for use in chat.\
 
 `$CellToStringDebug;
 `$CurrentCell;
+`$defaultMaxCellStringLength;
+`$defaultMaxOutputCellStringLength;
 `documentationSearchAPI;
 `escapeMarkdownString;
-`$maxOutputCellStringLength;
+`truncateString;
 
 Begin[ "`Private`" ];
 
-Needs[ "Wolfram`Chatbook`"            ];
-Needs[ "Wolfram`Chatbook`ErrorUtils`" ];
-Needs[ "Wolfram`Chatbook`FrontEnd`"   ];
-Needs[ "Wolfram`Chatbook`Prompting`"  ];
+Needs[ "Wolfram`Chatbook`"              ];
+Needs[ "Wolfram`Chatbook`ChatMessages`" ];
+Needs[ "Wolfram`Chatbook`Common`"       ];
+Needs[ "Wolfram`Chatbook`ErrorUtils`"   ];
+Needs[ "Wolfram`Chatbook`FrontEnd`"     ];
+Needs[ "Wolfram`Chatbook`Models`"       ];
+Needs[ "Wolfram`Chatbook`Prompting`"    ];
+Needs[ "Wolfram`Chatbook`Tools`"        ];
+Needs[ "Wolfram`Chatbook`Utils`"        ];
 
 (* ::**************************************************************************************************************:: *)
 (* ::Section::Closed:: *)
@@ -39,13 +46,23 @@ $$outputStyle      = "Output"|"Print"|"Echo";
 $cellCharacterEncoding = "Unicode";
 
 (* Set a max string length for output cells to avoid blowing up token counts *)
-$maxOutputCellStringLength = 500;
+$maxOutputCellStringLength        = Automatic;
+$defaultMaxOutputCellStringLength = 500;
 
 (* Set an overall max string length for any type of cell *)
-$maxCellStringLength = 5000;
+$maxCellStringLength        = Automatic;
+$defaultMaxCellStringLength = 10000;
 
 (* Set a page width for expressions that need to be serialized as InputForm *)
-$cellPageWidth = 100;
+$cellPageWidth        = 100;
+$defaultCellPageWidth = $cellPageWidth;
+
+(* Window width to use when converting cells to multimodal images (Automatic means derive from $cellPageWidth):  *)
+$windowWidth        = Automatic;
+$defaultWindowWidth = 625;
+
+(* Maximum number of images to include in multimodal messages per cell before switching to a fully rasterized cell: *)
+$maxMarkdownBoxes = 5;
 
 (* Whether to collect data that can help discover missing definitions *)
 $CellToStringDebug = False;
@@ -90,6 +107,8 @@ $graphicsHeads = Alternatives[
     Graphics3DBox
 ];
 
+$$graphicsBox = $graphicsHeads[ ___ ] | TemplateBox[ _, "Legended", ___ ];
+
 (* Serialize the first argument of these and ignore the rest *)
 $stringStripHeads = Alternatives[
     ButtonBox,
@@ -173,22 +192,40 @@ WOLFRAM_ALPHA_PARSED_INPUT: %%Code%%
 CellToString // SetFallthroughError;
 
 CellToString // Options = {
-    CharacterEncoding        -> $cellCharacterEncoding,
-    "CharacterNormalization" -> "NFKC", (* FIXME: do this *)
-    "Debug"                  :> $CellToStringDebug,
-    PageWidth                -> $cellPageWidth
+    "CharacterEncoding"         -> $cellCharacterEncoding,
+    "CharacterNormalization"    -> "NFKC", (* FIXME: do this *)
+    "Debug"                     :> $CellToStringDebug,
+    "MaxCellStringLength"       -> $maxCellStringLength,
+    "MaxOutputCellStringLength" -> $maxOutputCellStringLength,
+    "PageWidth"                 -> $cellPageWidth,
+    "WindowWidth"               -> $windowWidth
 };
 
 (* :!CodeAnalysis::BeginBlock:: *)
 (* :!CodeAnalysis::Disable::SuspiciousSessionSymbol:: *)
 CellToString[ cell_, opts: OptionsPattern[ ] ] :=
-    Block[
+    Catch @ Block[
         {
             $cellCharacterEncoding = OptionValue[ "CharacterEncoding" ],
-            $CellToStringDebug     = TrueQ @ OptionValue[ "Debug" ],
-            $cellPageWidth         = OptionValue[ "PageWidth" ]
+            $CellToStringDebug = TrueQ @ OptionValue[ "Debug" ],
+            $cellPageWidth, $windowWidth, $maxCellStringLength, $maxOutputCellStringLength
         },
-        $fasterCellToStringFailBag = Internal`Bag[ ];
+        $cellPageWidth = toSize[ OptionValue @ PageWidth, $defaultCellPageWidth ];
+        $windowWidth = toWindowWidth[ OptionValue @ WindowWidth, $cellPageWidth ];
+
+        $maxCellStringLength = Ceiling @ toSize[
+            OptionValue[ "MaxCellStringLength" ],
+            $defaultMaxCellStringLength
+        ];
+
+        If[ $maxCellStringLength <= 0, Throw[ "[Cell Excised]" ] ];
+
+        $maxOutputCellStringLength = Ceiling @ toSize[
+            OptionValue[ "MaxOutputCellStringLength" ],
+            $defaultMaxOutputCellStringLength
+        ];
+
+        If[ $CellToStringDebug, $fasterCellToStringFailBag = Internal`Bag[ ] ];
         If[ ! StringQ @ $cellCharacterEncoding, $cellCharacterEncoding = "UTF-8" ];
         WithCleanup[
             Replace[
@@ -204,10 +241,25 @@ CellToString[ cell_, opts: OptionsPattern[ ] ] :=
     ];
 (* :!CodeAnalysis::EndBlock:: *)
 
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
+(*toSize*)
+toSize // beginDefinition;
+toSize[ size: $$size, default_ ] := size;
+toSize[ size_, default: $$size ] := default;
+toSize // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
+(*toWindowWidth*)
+toWindowWidth[ width: $$size, pageWidth_ ] := width;
+toWindowWidth[ width_, pageWidth: $$size ] := 6.25 * pageWidth;
+toWindowWidth[ ___ ] := $defaultWindowWidth;
+
 (* ::**************************************************************************************************************:: *)
 (* ::Subsection::Closed:: *)
 (*cellToString*)
-cellToString // SetFallthroughError;
+cellToString // beginDefinition;
 
 (* Argument normalization *)
 cellToString[ data: _TextData|_BoxData|_RawData ] := cellToString @ Cell @ data;
@@ -311,6 +363,8 @@ cellToString[ cell: Cell[ _String, "ChatOutput", ___ ] ] := Block[ { $escapeMark
 cellToString[ cell: Cell[ _TextData|_String, ___ ] ] := Block[ { $escapeMarkdown = True }, cellToString0 @ cell ];
 cellToString[ cell_ ] := Block[ { $escapeMarkdown = False }, cellToString0 @ cell ];
 
+cellToString // endDefinition;
+
 (* Recursive serialization of the cell content *)
 cellToString0[ cell0_ ] :=
     With[
@@ -346,10 +400,10 @@ fasterCellToString[ arg_ ] :=
 
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsubsection::Closed:: *)
-(*Ignored/Skipped*)
-
-fasterCellToString0[ $ignoredBoxPatterns ] := "";
-fasterCellToString0[ $stringStripHeads[ a_, ___ ] ] := fasterCellToString0 @ a;
+(*Multimodal Cell Images*)
+fasterCellToString0[ cell: Cell[ _BoxData, ___ ] ] /;
+    $multimodalMessages && Count[ cell, $$graphicsBox, Infinity ] > $maxMarkdownBoxes :=
+        toMarkdownImageBox @ cell;
 
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsubsection::Closed:: *)
@@ -361,6 +415,15 @@ fasterCellToString0[ (Cell|StyleBox)[ a_, "Subsubsubsection", ___ ] ] := "#### "
 fasterCellToString0[ (Cell|StyleBox)[ a_, "Subsubsubsubsection", ___ ] ] := "##### "<>fasterCellToString0 @ a;
 fasterCellToString0[ (Cell|StyleBox)[ a_, "ChatBlockDivider", ___ ] ] := "# "<>fasterCellToString0 @ a;
 
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsubsection::Closed:: *)
+(*Styles*)
+fasterCellToString0[ (h: Cell|StyleBox)[ a__, FontWeight -> Bold|"Bold", b___ ] ] :=
+    "**" <> fasterCellToString0 @ h[ a, b ] <> "**";
+
+fasterCellToString0[ (h: Cell|StyleBox)[ a__, FontSlant -> Italic|"Italic", b___ ] ] :=
+    "*" <> fasterCellToString0 @ h[ a, b ] <> "*";
+
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsubsection::Closed:: *)
 (*String Normalization*)
@@ -481,7 +544,7 @@ fasterCellToString0[ NamespaceBox[
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsubsection::Closed:: *)
 (*Graphics*)
-fasterCellToString0[ box: GraphicsBox[ TagBox[ RasterBox[ _, r___ ], t___ ], g___ ] ] :=
+fasterCellToString0[ box: GraphicsBox[ TagBox[ RasterBox[ _, r___ ], t___ ], g___ ] ] /; ! TrueQ @ $multimodalMessages :=
     StringJoin[
         "\\!\\(\\*",
         StringReplace[
@@ -491,23 +554,66 @@ fasterCellToString0[ box: GraphicsBox[ TagBox[ RasterBox[ _, r___ ], t___ ], g__
         "\\)"
     ];
 
-fasterCellToString0[ box: $graphicsHeads[ ___ ] ] :=
-    If[ TrueQ[ ByteCount @ box < $maxOutputCellStringLength ],
+fasterCellToString0[ box: $$graphicsBox ] :=
+    Which[
+        (* If in multimodal mode, sow the rasterized box and insert the id: *)
+        TrueQ @ $multimodalMessages,
+        toMarkdownImageBox @ box,
+
         (* For relatively small graphics expressions, we'll give an InputForm string *)
-        needsBasePrompt[ "Notebooks" ];
-        truncateString @ makeGraphicsString @ box,
+        TrueQ[ ByteCount @ box < $maxOutputCellStringLength ],
+        (
+            needsBasePrompt[ "Notebooks" ];
+            truncateString @ makeGraphicsString @ box
+        ),
+
         (* Otherwise, give the same thing you'd get in a standalone kernel*)
-        needsBasePrompt[ "ConversionGraphics" ];
-        truncateString[ "\\!\\(\\*" <> StringReplace[ inputFormString @ box, $graphicsBoxStringReplacements ] <> "\\)" ]
+        True,
+        (
+            needsBasePrompt[ "ConversionGraphics" ];
+            truncateString[
+                "\\!\\(\\*" <> StringReplace[ inputFormString @ box, $graphicsBoxStringReplacements ] <> "\\)"
+            ]
+        )
     ];
 
 
+
 $graphicsBoxStringReplacements = {
     a: DigitCharacter ~~ "." ~~ b: Repeated[ DigitCharacter, { 4, Infinity } ] :> a <> "." <> StringTake[ b, 3 ],
     "\"$$DATA$$\"" -> "...",
     "$$DATA$$" -> "..."
 };
 
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsubsubsection::Closed:: *)
+(*toMarkdownImageBox*)
+toMarkdownImageBox // beginDefinition;
+
+toMarkdownImageBox[ graphics_ ] := Enclose[
+    Module[ { img, uri },
+        img    = ConfirmBy[ rasterizeGraphics @ graphics, ImageQ, "RasterizeGraphics" ];
+        uri    = ConfirmBy[ MakeExpressionURI[ "image", img ], StringQ, "RasterID" ];
+        needsBasePrompt[ "MarkdownImageBox" ];
+        "\\!\\(\\*MarkdownImageBox[\"" <> uri <> "\"]\\)"
+    ],
+    throwInternalFailure[ toMarkdownImageBox @ graphics, ## ] &
+];
+
+toMarkdownImageBox // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsubsubsection::Closed:: *)
+(*rasterizeGraphics*)
+rasterizeGraphics // beginDefinition;
+rasterizeGraphics[ gfx: $$graphicsBox ] := rasterizeGraphics[ gfx ] = Rasterize @ RawBoxes @ gfx;
+rasterizeGraphics[ cell_Cell ] := rasterizeGraphics[ cell, 6.25*$cellPageWidth ];
+
+rasterizeGraphics[ cell_Cell, width_Real ] := rasterizeGraphics[ cell, width ] =
+    Rasterize @ Append[ cell, PageWidth -> width ];
+
+rasterizeGraphics // endDefinition;
+
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsubsection::Closed:: *)
 (*Template Boxes*)
@@ -525,6 +631,12 @@ fasterCellToString0[ StyleBox[ code_, "TI", ___ ] ] :=
         "``" <> fasterCellToString0 @ code <> "``"
     ];
 
+fasterCellToString0[ Cell[ code_, "InlineCode", ___ ] ] :=
+    Block[ { $escapeMarkdown = False },
+        needsBasePrompt[ "DoubleBackticks" ];
+        "``" <> fasterCellToString0 @ code <> "``"
+    ];
+
 (* Messages *)
 fasterCellToString0[ TemplateBox[ args: { _, _, str_String, ___ }, "MessageTemplate" ] ] := (
     needsBasePrompt[ "WolframLanguage" ];
@@ -575,6 +687,17 @@ fasterCellToString0[ ButtonBox[ StyleBox[ label_, "SymbolsRefLink", ___ ], ___,
     "[" <> fasterCellToString0 @ label <> "](" <> uri <> ")"
 );
 
+fasterCellToString0[
+    ButtonBox[
+        label_,
+        OrderlessPatternSequence[
+            BaseStyle  -> "Hyperlink",
+            ButtonData -> { url: _String|_URL, _ },
+            ___
+        ]
+    ]
+] := "[" <> fasterCellToString0 @ label <> "](" <> TextString @ url <> ")";
+
 (* TeXAssistantTemplate *)
 fasterCellToString0[ TemplateBox[ KeyValuePattern[ "input" -> string_ ], "TeXAssistantTemplate" ] ] := (
     needsBasePrompt[ "Math" ];
@@ -805,6 +928,12 @@ fasterCellToString0[ DynamicModuleBox[ a___ ] ] /; ! TrueQ @ $CellToStringDebug
     "DynamicModule[<<" <> ToString @ Length @ HoldComplete @ a <> ">>]"
 );
 
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsubsection::Closed:: *)
+(*Ignored/Skipped*)
+fasterCellToString0[ $ignoredBoxPatterns ] := "";
+fasterCellToString0[ $stringStripHeads[ a_, ___ ] ] := fasterCellToString0 @ a;
+
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsubsection::Closed:: *)
 (*Missing Definition*)
@@ -940,14 +1069,13 @@ escapeMarkdownCharactersQ[ ___ ] := True;
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsection::Closed:: *)
 (*truncateString*)
-truncateString // SetFallthroughError;
+truncateString // beginDefinition;
 truncateString[ str_String ] := truncateString[ str, $maxOutputCellStringLength ];
-truncateString[ str_String, max_Integer ] := truncateString[ str, Ceiling[ max / 2 ], Floor[ max / 2 ] ];
-truncateString[ str_String, l_Integer, r_Integer ] /; StringLength @ str <= l + r + 5 := str;
-truncateString[ str_String, l_Integer, r_Integer ] := StringTake[ str, l ] <> " ... " <> StringTake[ str, -r ];
+truncateString[ str_String, Automatic ] := truncateString[ str, $defaultMaxOutputCellStringLength ];
+truncateString[ str_String, max: $$size ] := stringTrimMiddle[ str, max ];
 truncateString[ other_ ] := other;
 truncateString[ other_, _Integer ] := other;
-truncateString[ other_, _Integer, _Integer ] := other;
+truncateString // endDefinition;
 
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsection::Closed:: *)
@@ -1282,5 +1410,9 @@ firstMatchingCellGroup[ nb_, patt_, "Content" ] := Catch[
 (* ::**************************************************************************************************************:: *)
 (* ::Section::Closed:: *)
 (*Package Footer*)
+If[ Wolfram`ChatbookInternal`$BuildingMX,
+    Null;
+];
+
 End[ ];
 EndPackage[ ];
diff --git a/Source/Chatbook/Settings.wl b/Source/Chatbook/Settings.wl
index a2639a37..abbc46d5 100644
--- a/Source/Chatbook/Settings.wl
+++ b/Source/Chatbook/Settings.wl
@@ -20,43 +20,49 @@ Needs[ "Wolfram`Chatbook`FrontEnd`" ];
 (* ::Section::Closed:: *)
 (*Configuration*)
 $defaultChatSettings = <|
-    "Assistance"               -> Automatic,
-    "AutoFormat"               -> True,
-    "BasePrompt"               -> Automatic,
-    "ChatContextPreprompt"     -> Automatic,
-    "ChatDrivenNotebook"       -> False,
-    "ChatHistoryLength"        -> 25,
-    "DynamicAutoFormat"        -> Automatic,
-    "EnableChatGroupSettings"  -> False,
-    "EnableLLMServices"        -> Automatic, (* TODO: remove this once LLMServices is widely available *)
-    "FrequencyPenalty"         -> 0.1,
-    "HandlerFunctions"         :> $DefaultChatHandlerFunctions,
-    "HandlerFunctionsKeys"     -> Automatic,
-    "IncludeHistory"           -> Automatic,
-    "InitialChatCell"          -> True,
-    "LLMEvaluator"             -> "CodeAssistant",
-    "MaxTokens"                -> Automatic,
-    "MergeMessages"            -> True,
-    "Model"                    :> $DefaultModel,
-    "NotebookWriteMethod"      -> Automatic,
-    "OpenAIKey"                -> Automatic, (* TODO: remove this once LLMServices is widely available *)
-    "PresencePenalty"          -> 0.1,
-    "ProcessingFunctions"      :> $DefaultChatProcessingFunctions,
-    "Prompts"                  -> { },
-    "ShowMinimized"            -> Automatic,
-    "StreamingOutputMethod"    -> Automatic,
-    "Temperature"              -> 0.7,
-    "ToolOptions"              :> $DefaultToolOptions,
-    "Tools"                    -> Automatic,
-    "ToolsEnabled"             -> Automatic,
-    "TopP"                     -> 1,
-    "TrackScrollingWhenPlaced" -> Automatic
+    "Assistance"                -> Automatic,
+    "AutoFormat"                -> True,
+    "BasePrompt"                -> Automatic,
+    "ChatContextPreprompt"      -> Automatic,
+    "ChatDrivenNotebook"        -> False,
+    "ChatHistoryLength"         -> 100,
+    "DynamicAutoFormat"         -> Automatic,
+    "EnableChatGroupSettings"   -> False,
+    "EnableLLMServices"         -> Automatic, (* TODO: remove this once LLMServices is widely available *)
+    "FrequencyPenalty"          -> 0.1,
+    "HandlerFunctions"          :> $DefaultChatHandlerFunctions,
+    "HandlerFunctionsKeys"      -> Automatic,
+    "IncludeHistory"            -> Automatic,
+    "InitialChatCell"           -> True,
+    "LLMEvaluator"              -> "CodeAssistant",
+    "MaxCellStringLength"       -> Automatic,
+    "MaxContextTokens"          -> Automatic,
+    "MaxOutputCellStringLength" -> Automatic,
+    "MaxTokens"                 -> Automatic,
+    "MergeMessages"             -> True,
+    "Model"                     :> $DefaultModel,
+    "Multimodal"                -> Automatic,
+    "NotebookWriteMethod"       -> Automatic,
+    "OpenAIKey"                 -> Automatic, (* TODO: remove this once LLMServices is widely available *)
+    "PresencePenalty"           -> 0.1,
+    "ProcessingFunctions"       :> $DefaultChatProcessingFunctions,
+    "Prompts"                   -> { },
+    "ShowMinimized"             -> Automatic,
+    "StreamingOutputMethod"     -> Automatic,
+    "Temperature"               -> 0.7,
+    "Tokenizer"                 -> Automatic,
+    "ToolOptions"               :> $DefaultToolOptions,
+    "Tools"                     -> Automatic,
+    "ToolsEnabled"              -> Automatic,
+    "TopP"                      -> 1,
+    "TrackScrollingWhenPlaced"  -> Automatic
 |>;
 
 (* ::**************************************************************************************************************:: *)
 (* ::Subsection::Closed:: *)
 (*Argument Patterns*)
 $$feObj = _FrontEndObject | $FrontEndSession | _NotebookObject | _CellObject | _BoxObject;
+$$validRootSettingValue = Inherited | _? (AssociationQ@*Association);
 
 (* ::**************************************************************************************************************:: *)
 (* ::Section::Closed:: *)
@@ -140,21 +146,120 @@ CurrentChatSettings[ args___ ] :=
 (* ::**************************************************************************************************************:: *)
 (* ::Subsection::Closed:: *)
 (*UpValues*)
-CurrentChatSettings /: HoldPattern @ Set[ CurrentChatSettings[ obj0_, key_String ], value_ ] :=
-    With[ { obj = obj0 },
-        (CurrentValue[ obj, { TaggingRules, "ChatNotebookSettings", key } ] = value) /; MatchQ[ obj, $$feObj ]
-    ];
+CurrentChatSettings /: HoldPattern @ Set[ CurrentChatSettings[ args___ ], value_ ] :=
+    catchTop[ UsingFrontEnd @ setCurrentChatSettings[ args, value ], CurrentChatSettings ];
+
+CurrentChatSettings /: HoldPattern @ Unset[ CurrentChatSettings[ args___ ] ] :=
+    catchTop[ UsingFrontEnd @ unsetCurrentChatSettings @ args, CurrentChatSettings ];
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*setCurrentChatSettings*)
+setCurrentChatSettings // beginDefinition;
+
+(* Root settings: *)
+setCurrentChatSettings[ value: $$validRootSettingValue ] :=
+    setCurrentChatSettings0[ $FrontEnd, value ];
+
+setCurrentChatSettings[ obj: $$feObj, value: $$validRootSettingValue ] :=
+    setCurrentChatSettings0[ obj, value ];
+
+(* Key settings: *)
+setCurrentChatSettings[ key_String? StringQ, value_ ] :=
+    setCurrentChatSettings0[ $FrontEnd, key, value ];
+
+setCurrentChatSettings[ obj: $$feObj, key_String? StringQ, value_ ] :=
+    setCurrentChatSettings0[ obj, key, value ];
+
+(* Invalid scope: *)
+setCurrentChatSettings[ obj: Except[ $$feObj ], a__ ] := throwFailure[
+    "InvalidFrontEndScope",
+    obj,
+    CurrentChatSettings,
+    HoldForm @ setCurrentChatSettings[ obj, a ]
+];
+
+(* Invalid key: *)
+setCurrentChatSettings[ obj: $$feObj, key_, value_ ] := throwFailure[
+    "InvalidSettingsKey",
+    key,
+    CurrentChatSettings,
+    HoldForm @ setCurrentChatSettings[ obj, key, value ]
+];
+
+(* Invalid root settings: *)
+setCurrentChatSettings[ value: Except[ $$validRootSettingValue ] ] := throwFailure[
+    "InvalidRootSettings",
+    value,
+    CurrentChatSettings,
+    HoldForm @ setCurrentChatSettings @ value
+];
+
+setCurrentChatSettings[ obj: $$feObj, value: Except[ $$validRootSettingValue ] ] := throwFailure[
+    "InvalidRootSettings",
+    value,
+    CurrentChatSettings,
+    HoldForm @ setCurrentChatSettings @ value
+];
 
-CurrentChatSettings /: HoldPattern @ Set[ CurrentChatSettings[ key_String ], value_ ] :=
-    CurrentValue[ $currentEvaluationObject, { TaggingRules, "ChatNotebookSettings", key } ] = value;
+setCurrentChatSettings // endDefinition;
 
-CurrentChatSettings /: HoldPattern @ Unset[ CurrentChatSettings[ obj0_, key_String ] ] :=
-    With[ { obj = obj0 },
-        (CurrentValue[ obj, { TaggingRules, "ChatNotebookSettings", key } ] = Inherited) /; MatchQ[ obj, $$feObj ]
+
+setCurrentChatSettings0 // beginDefinition;
+
+setCurrentChatSettings0[ scope: $$feObj, Inherited ] :=
+    CurrentValue[ scope, { TaggingRules, "ChatNotebookSettings" } ] = Inherited;
+
+setCurrentChatSettings0[ scope: $$feObj, value_ ] :=
+    With[ { as = Association @ value },
+        (CurrentValue[ scope, { TaggingRules, "ChatNotebookSettings" } ] = as) /; AssociationQ @ as
     ];
 
-CurrentChatSettings /: HoldPattern @ Unset[ CurrentChatSettings[ key_String ] ] :=
-    CurrentValue[ $currentEvaluationObject, { TaggingRules, "ChatNotebookSettings", key } ] = Inherited;
+setCurrentChatSettings0[ scope: $$feObj, key_String? StringQ, value_ ] :=
+    CurrentValue[ scope, { TaggingRules, "ChatNotebookSettings", key } ] = value;
+
+setCurrentChatSettings0 // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*unsetCurrentChatSettings*)
+unsetCurrentChatSettings // beginDefinition;
+
+(* Root settings: *)
+unsetCurrentChatSettings[ ] := unsetCurrentChatSettings0 @ $FrontEnd;
+unsetCurrentChatSettings[ obj: $$feObj ] := unsetCurrentChatSettings0 @ obj;
+
+(* Key settings: *)
+unsetCurrentChatSettings[ key_? StringQ ] := unsetCurrentChatSettings0[ $FrontEnd, key ];
+unsetCurrentChatSettings[ obj: $$feObj, key_? StringQ ] := unsetCurrentChatSettings0[ obj, key ];
+
+(* Invalid scope: *)
+unsetCurrentChatSettings[ obj: Except[ $$feObj ], a___ ] := throwFailure[
+    "InvalidFrontEndScope",
+    obj,
+    CurrentChatSettings,
+    HoldForm @ unsetCurrentChatSettings[ obj, a ]
+];
+
+(* Invalid key: *)
+unsetCurrentChatSettings[ obj: $$feObj, key_ ] := throwFailure[
+    "InvalidSettingsKey",
+    key,
+    CurrentChatSettings,
+    HoldForm @ unsetCurrentChatSettings[ obj, key ]
+];
+
+unsetCurrentChatSettings // endDefinition;
+
+unsetCurrentChatSettings0 // beginDefinition;
+
+unsetCurrentChatSettings0[ obj: $$feObj ] :=
+    (CurrentValue[ obj, { TaggingRules, "ChatNotebookSettings" } ] = Inherited);
+
+unsetCurrentChatSettings0[ obj: $$feObj, key_? StringQ ] :=
+    (CurrentValue[ obj, { TaggingRules, "ChatNotebookSettings" } ] = Inherited);
+
+unsetCurrentChatSettings0 // endDefinition;
 
 (* ::**************************************************************************************************************:: *)
 (* ::Subsection::Closed:: *)
@@ -293,6 +398,8 @@ mergeChatSettings0[ { e_ } ] := e;
 mergeChatSettings0[ { } ] := Missing[ ];
 mergeChatSettings0 // endDefinition;
 
+(* TODO: need to apply special merging/inheritance for things like "Prompts" *)
+
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsection::Closed:: *)
 (*getPrecedingDelimiter*)
diff --git a/Source/Chatbook/Tools.wl b/Source/Chatbook/Tools.wl
index b2f96f35..d52ecd52 100644
--- a/Source/Chatbook/Tools.wl
+++ b/Source/Chatbook/Tools.wl
@@ -828,7 +828,7 @@ documentationBasicExamples // endDefinition;
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsubsection::Closed:: *)
 (*cellToString*)
-cellToString[ args___ ] := Block[ { $maxOutputCellStringLength = 100 }, CellToString @ args ];
+cellToString[ args___ ] := CellToString[ args, "MaxCellStringLength" -> 100 ];
 
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsection::Closed:: *)
@@ -1489,31 +1489,40 @@ MakeExpressionURI[ args: Repeated[ _, { 1, 3 } ] ] := makeExpressionURI @ args;
 (* ::Subsection::Closed:: *)
 (*GetExpressionURIs*)
 GetExpressionURIs // ClearAll;
+GetExpressionURIs // Options = { Tooltip -> Automatic };
 
-GetExpressionURIs[ str_ ] := GetExpressionURIs[ str, ## & ];
+GetExpressionURIs[ str_, opts: OptionsPattern[ ] ] :=
+    GetExpressionURIs[ str, ## &, opts ];
 
-GetExpressionURIs[ str_String, wrapper_ ] := catchMine @ StringSplit[
-    str,
-    link: Shortest[ "![" ~~ __ ~~ "](" ~~ __ ~~ ")" ] :> catchAlways @ GetExpressionURI[ link, wrapper ]
-];
+GetExpressionURIs[ str_String, wrapper_, opts: OptionsPattern[ ] ] :=
+    catchMine @ Block[ { $uriTooltip = OptionValue @ Tooltip },
+        StringSplit[
+            str,
+            link: Shortest[ "![" ~~ __ ~~ "](" ~~ __ ~~ ")" ] :> catchAlways @ GetExpressionURI[ link, wrapper ]
+        ]
+    ];
 
 (* ::**************************************************************************************************************:: *)
 (* ::Subsection::Closed:: *)
 (*GetExpressionURI*)
 GetExpressionURI // ClearAll;
+GetExpressionURI // Options = { Tooltip -> Automatic };
 
-GetExpressionURI[ uri_ ] := catchMine @ GetExpressionURI[ uri, ## & ];
-GetExpressionURI[ URL[ uri_ ], wrapper_ ] := catchMine @ GetExpressionURI[ uri, wrapper ];
+GetExpressionURI[ uri_, opts: OptionsPattern[ ] ] :=
+    catchMine @ GetExpressionURI[ uri, ## &, opts ];
 
-GetExpressionURI[ uri_String, wrapper_ ] := catchMine @ Enclose[
+GetExpressionURI[ URL[ uri_ ], wrapper_, opts: OptionsPattern[ ] ] :=
+    catchMine @ GetExpressionURI[ uri, wrapper, opts ];
+
+GetExpressionURI[ uri_String, wrapper_, opts: OptionsPattern[ ] ] := catchMine @ Enclose[
     Module[ { held },
-        held = ConfirmMatch[ getExpressionURI @ uri, _HoldComplete, "GetExpressionURI" ];
+        held = ConfirmMatch[ getExpressionURI[ uri, OptionValue[ Tooltip ] ], _HoldComplete, "GetExpressionURI" ];
         wrapper @@ held
     ],
     throwInternalFailure[ GetExpressionURI[ uri, wrapper ], ## ] &
 ];
 
-GetExpressionURI[ All, wrapper_ ] := catchMine @ Enclose[
+GetExpressionURI[ All, wrapper_, opts: OptionsPattern[ ] ] := catchMine @ Enclose[
     Module[ { attachments },
         attachments = ConfirmBy[ $attachments, AssociationQ, "Attachments" ];
         ConfirmAssert[ AllTrue[ attachments, MatchQ[ _HoldComplete ] ], "HeldAttachments" ];
@@ -1524,26 +1533,31 @@ GetExpressionURI[ All, wrapper_ ] := catchMine @ Enclose[
 
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsection::Closed:: *)
-(*getExpressionURI*)
+(*getExpressionURI0*)
 getExpressionURI // beginDefinition;
+getExpressionURI[ uri_, tooltip_ ] := Block[ { $tooltip = tooltip }, getExpressionURI0 @ uri ];
+getExpressionURI // endDefinition;
 
-getExpressionURI[ str_String ] :=
+
+getExpressionURI0 // beginDefinition;
+
+getExpressionURI0[ str_String ] :=
     Module[ { split },
         split = First[ StringSplit[ str, "![" ~~ alt__ ~~ "](" ~~ url__ ~~ ")" :> { alt, url } ], $Failed ];
-        getExpressionURI @@ split /; MatchQ[ split, { _String, _String } ]
+        getExpressionURI0 @@ split /; MatchQ[ split, { _String, _String } ]
     ];
 
-getExpressionURI[ uri_String ] := getExpressionURI[ None, uri ];
+getExpressionURI0[ uri_String ] := getExpressionURI0[ None, uri ];
 
-getExpressionURI[ tooltip_, uri_String ] := getExpressionURI[ tooltip, uri, URLParse @ uri ];
+getExpressionURI0[ tooltip_, uri_String ] := getExpressionURI0[ tooltip, uri, URLParse @ uri ];
 
-getExpressionURI[ tooltip_, uri_, as: KeyValuePattern @ { "Scheme" -> $$expressionScheme, "Domain" -> key_ } ] :=
+getExpressionURI0[ tooltip_, uri_, as: KeyValuePattern @ { "Scheme" -> $$expressionScheme, "Domain" -> key_ } ] :=
     Enclose[
         ConfirmMatch[ displayAttachment[ uri, tooltip, key ], _HoldComplete, "DisplayAttachment" ],
-        throwInternalFailure[ getExpressionURI[ tooltip, uri, as ], ## ] &
+        throwInternalFailure[ getExpressionURI0[ tooltip, uri, as ], ## ] &
     ];
 
-getExpressionURI // endDefinition;
+getExpressionURI0 // endDefinition;
 
 (* ::**************************************************************************************************************:: *)
 (* ::Subsubsection::Closed:: *)
@@ -1556,7 +1570,11 @@ displayAttachment[ uri_, None, key_ ] :=
 displayAttachment[ uri_, tooltip_String, key_ ] := Enclose[
     Replace[
         ConfirmMatch[ getAttachment[ uri, key ], _HoldComplete, "GetAttachment" ],
-        HoldComplete[ expr_ ] :> HoldComplete @ Tooltip[ expr, tooltip ]
+        HoldComplete[ expr_ ] :>
+            If[ TrueQ @ $tooltip,
+                HoldComplete @ Tooltip[ expr, tooltip ],
+                HoldComplete @ expr
+            ]
     ],
     throwInternalFailure[ displayAttachment[ uri, tooltip, key ], ## ] &
 ];
@@ -1578,6 +1596,8 @@ getAttachment // endDefinition;
 (*makeToolResponseString*)
 makeToolResponseString // beginDefinition;
 
+makeToolResponseString[ failure_Failure ] := makeFailureString @ failure;
+
 makeToolResponseString[ expr_? simpleResultQ ] :=
     With[ { string = fixLineEndings @ TextString @ expr },
         If[ StringLength @ string < $toolResultStringLength,
diff --git a/Source/Chatbook/Utils.wl b/Source/Chatbook/Utils.wl
index 17d57911..1cd71a84 100644
--- a/Source/Chatbook/Utils.wl
+++ b/Source/Chatbook/Utils.wl
@@ -1,99 +1,27 @@
-(*
-	This package contains utility functions that are not tied to Chatbook
-	directly in any way.
-*)
+(* ::Section::Closed:: *)
+(*Package Header*)
+BeginPackage[ "Wolfram`Chatbook`Utils`" ];
+
+HoldComplete[
+    `associationKeyDeflatten;
+    `convertUTF8;
+    `fastFileHash;
+    `fixLineEndings;
+    `getPinkBoxErrors;
+    `graphicsQ;
+    `image2DQ;
+    `makeFailureString;
+    `readString;
+    `stringTrimMiddle;
+    `validGraphicsQ;
+];
 
-(* cSpell: ignore deflatten *)
+Begin[ "`Private`" ];
 
-BeginPackage["Wolfram`Chatbook`Utils`"]
-
-`associationKeyDeflatten;
-`convertUTF8;
-`fixLineEndings;
-
-CellPrint2
-
-FirstMatchingPositionOrder::usage = "FirstMatchingPositionOrder[patterns][a, b] returns an ordering value based on the positions of the first pattern in patterns to match a and b."
-
-Begin["`Private`"]
-
-Needs[ "Wolfram`Chatbook`"            ];
-Needs[ "Wolfram`Chatbook`Common`"     ];
-Needs[ "Wolfram`Chatbook`ErrorUtils`" ];
-Needs[ "Wolfram`Chatbook`UI`"         ];
-
-(*====================================*)
-
-SetFallthroughError[CellPrint2]
-
-(*
-	Alternative to CellPrint[] where the first argument is an evaluation input
-	cell, and the new cell will be printed after any existing output cells.
-
-	`CellPrint[arg]` is conceptually `CellPrint2[EvaluationCell[], arg]`.
-*)
-CellPrint2[
-	evalCell_CellObject,
-	Cell[cellData_, cellStyles___?StringQ, cellOpts___?OptionQ]
-] := With[{
-	uuid = CreateUUID[]
-}, Module[{
-	cell = Cell[
-		cellData,
-		cellStyles,
-		GeneratedCell -> True,
-		CellAutoOverwrite -> True,
-		ExpressionUUID -> uuid,
-		cellOpts
-	],
-	obj
-},
-	RaiseAssert[
-		Experimental`CellExistsQ[evalCell],
-		"Unable to print cell: evaluation cell does not exist."
-	];
-
-	Wolfram`Chatbook`UI`Private`moveAfterPreviousOutputs[evalCell];
-
-	RaiseConfirm @ NotebookWrite[ParentNotebook[evalCell], cell];
-
-	obj = CellObject[uuid];
-
-	RaiseAssert[
-		Experimental`CellExistsQ[obj],
-		<| "CellExpression" -> cell |>,
-		"Error printing cell: written cell was not created or could not be found."
-	];
-
-	obj
-]]
-
-(*====================================*)
-
-FirstMatchingPositionOrder[patterns_?ListQ][a_, b_] := Module[{
-	aPos,
-	bPos
-},
-	aPos = FirstPosition[patterns, _?(patt |-> MatchQ[a, patt]), None, {1}];
-	bPos = FirstPosition[patterns, _?(patt |-> MatchQ[b, patt]), None, {1}];
-
-	Replace[{aPos, bPos}, {
-		(* If neither `a` nor `b` match, then they are already in order. *)
-		{None, None} -> True,
-		(* If only `a` matches, it's already in order. *)
-		{Except[None], None} -> True,
-		(* If only `b` matches, it should come earlier. *)
-		{None, Except[None]} -> -1,
-		(* If both `a` and `b` match, sort based on the position of the matched pattern. *)
-		{{aIdx_?IntegerQ}, {bIdx_?IntegerQ}} :> Order[aIdx, bIdx],
-		other_ :> FailureMessage[
-			FirstMatchingPositionOrder::unexpected,
-			"Unexpected position values: ``",
-			{other}
-		]
-	}]
-]
+Needs[ "Wolfram`Chatbook`"        ];
+Needs[ "Wolfram`Chatbook`Common`" ];
 
+(* cSpell: ignore deflatten *)
 (* ::**************************************************************************************************************:: *)
 (* ::Section::Closed:: *)
 (*AssociationKeyDeflatten*)
@@ -102,13 +30,17 @@ importResourceFunction[ associationKeyDeflatten, "AssociationKeyDeflatten" ];
 
 (* ::**************************************************************************************************************:: *)
 (* ::Section::Closed:: *)
+(*Strings*)
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
 (*fixLineEndings*)
 fixLineEndings // beginDefinition;
 fixLineEndings[ string_String? StringQ ] := StringReplace[ string, "\r\n" -> "\n" ];
 fixLineEndings // endDefinition;
 
 (* ::**************************************************************************************************************:: *)
-(* ::Section::Closed:: *)
+(* ::Subsection::Closed:: *)
 (*convertUTF8*)
 convertUTF8 // beginDefinition;
 convertUTF8[ string_String ] := convertUTF8[ string, True ];
@@ -116,6 +48,170 @@ convertUTF8[ string_String, True  ] := FromCharacterCode[ ToCharacterCode @ stri
 convertUTF8[ string_String, False ] := FromCharacterCode @ ToCharacterCode[ string, "UTF-8" ];
 convertUTF8 // endDefinition;
 
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
+(*stringTrimMiddle*)
+stringTrimMiddle // beginDefinition;
+stringTrimMiddle[ str_String, Infinity ] := str;
+stringTrimMiddle[ str_String, max_Integer? Positive ] := stringTrimMiddle[ str, Ceiling[ max / 2 ], Floor[ max / 2 ] ];
+stringTrimMiddle[ str_String, l_Integer, r_Integer ] /; StringLength @ str <= l + r + 5 := str;
+stringTrimMiddle[ str_String, l_Integer, r_Integer ] := StringTake[ str, l ] <> " ... " <> StringTake[ str, -r ];
+stringTrimMiddle // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
+(*makeFailureString*)
+makeFailureString // beginDefinition;
+
+makeFailureString[ failure: Failure[ tag_, as_Association ] ] := Enclose[
+    Module[ { message },
+        message = ToString @ ConfirmBy[ failure[ "Message" ], StringQ, "Message" ];
+        StringJoin[
+            "Failure[",
+                ToString[ tag, InputForm ],
+                ", ",
+                StringReplace[
+                    ToString[ as, InputForm ],
+                    StartOfString~~"<|" -> "<|" <> ToString[ "Message" -> message, InputForm ] <> ", "
+                ],
+            "]"
+        ]
+    ],
+    throwInternalFailure[ makeFailureString @ failure, ##1 ] &
+];
+
+makeFailureString // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Section::Closed:: *)
+(*Files*)
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
+(*readString*)
+readString // beginDefinition;
+
+readString[ file_ ] := Quiet[ readString[ file, ReadByteArray @ file ], $CharacterEncoding::utf8 ];
+
+readString[ file_, bytes_? ByteArrayQ ] := readString[ file, ByteArrayToString @ bytes ];
+readString[ file_, string_? StringQ   ] := fixLineEndings @ string;
+readString[ file_, failure_Failure    ] := failure;
+
+readString[ file_, $Failed ] :=
+    Module[ { exists, tag, template },
+        exists   = TrueQ @ FileExistsQ @ file;
+        tag      = If[ exists, "FileUnreadable", "FileNotFound" ];
+        template = If[ exists, "Cannot read content from `1`.", "The file `1` does not exist." ];
+        Failure[ tag, <| "MessageTemplate" -> template, "MessageParameters" -> { file } |> ]
+    ];
+
+readString // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsubsection::Closed:: *)
+(*unreadableFileFailure*)
+unreadableFileFailure // beginDefinition;
+
+unreadableFileFailure[ file_ ] :=
+    Failure[
+        "FileUnreadable",
+        <|
+            "MessageTemplate" -> "Cannot read content from `1`.",
+            "MessageParameters" -> { file }
+        |>
+    ];
+
+unreadableFileFailure // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
+(*fastFileHash*)
+fastFileHash // beginDefinition;
+fastFileHash[ file_ ] := fastFileHash[ file, ReadByteArray @ file ];
+fastFileHash[ file_, bytes_ByteArray ] := Hash @ bytes;
+fastFileHash // endDefinition;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Section::Closed:: *)
+(*Graphics*)
+$$graphics = HoldPattern @ Alternatives[
+    _System`AstroGraphics,
+    _GeoGraphics,
+    _Graphics,
+    _Graphics3D,
+    _Image,
+    _Image3D,
+    _Legended
+];
+
+$$definitelyNotGraphics = HoldPattern @ Alternatives[
+    _Association,
+    _CloudObject,
+    _File,
+    _List,
+    _String,
+    _URL,
+    Null,
+    True|False
+];
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
+(*graphicsQ*)
+graphicsQ[ $$graphics              ] := True;
+graphicsQ[ $$definitelyNotGraphics ] := False;
+graphicsQ[ g_                      ] := MatchQ[ Quiet @ Show @ Unevaluated @ g, $$graphics ];
+graphicsQ[ ___                     ] := False;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
+(*validGraphicsQ*)
+validGraphicsQ[ g_? graphicsQ ] := getPinkBoxErrors @ Unevaluated @ g === { };
+validGraphicsQ[ ___ ] := False;
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
+(*getPinkBoxErrors*)
+getPinkBoxErrors // beginDefinition;
+(* TODO: hook this up to evaluator outputs and CellToString to give feedback about pink boxes *)
+
+getPinkBoxErrors[ { } ] :=
+    { };
+
+getPinkBoxErrors[ cells: _CellObject | { __CellObject } ] :=
+    getPinkBoxErrors @ NotebookRead @ cells;
+
+getPinkBoxErrors[ cells: _Cell | { __Cell } ] :=
+    Module[ { nbo },
+        UsingFrontEnd @ WithCleanup[
+            nbo = NotebookPut[ Notebook @ Flatten @ { cells }, Visible -> False ],
+            SelectionMove[ nbo, All, Notebook ];
+            MathLink`CallFrontEnd @ FrontEnd`GetErrorsInSelectionPacket @ nbo,
+            NotebookClose @ nbo
+        ]
+    ];
+
+getPinkBoxErrors[ data: _TextData | _BoxData | { __BoxData } ] :=
+    getPinkBoxErrors @ Cell @ data;
+
+getPinkBoxErrors[ exprs_List ] :=
+    getPinkBoxErrors[ Cell @* BoxData /@ MakeBoxes /@ Unevaluated @ exprs ];
+
+getPinkBoxErrors[ expr_ ] :=
+    getPinkBoxErrors @ { Cell @ BoxData @ MakeBoxes @ expr };
+
+getPinkBoxErrors // endDefinition;
+
+
+(* ::**************************************************************************************************************:: *)
+(* ::Subsection::Closed:: *)
+(*image2DQ*)
+(* Matches against the head in addition to checking ImageQ to avoid passing Image3D when a 2D image is expected: *)
+image2DQ // beginDefinition;
+image2DQ[ _Image? ImageQ ] := True;
+image2DQ[ _              ] := False;
+image2DQ // endDefinition;
+
 (* ::**************************************************************************************************************:: *)
 (* ::Section::Closed:: *)
 (*Package Footer*)