From dc2739c8986fe40fb22297f4957e3d068bc51faa Mon Sep 17 00:00:00 2001
From: Hatterhat <31829017+Hatterhat@users.noreply.github.com>
Date: Thu, 25 Jun 2026 21:35:39 -0500
Subject: [PATCH] ChemMaster QoL: Reusable Custom Transfer Amounts (#96563)

## About The Pull Request


https://github.com/user-attachments/assets/a6c6d3d9-3284-4a45-80c4-14dbc4956cf8

Adds custom transfer amount functionality to the ChemMaster UI through a
number input (by the eject button) and paired button.

## Why It's Good For The Game

If I have to hit the one-off custom transfer button, several times in a
row, for my artisanal chemical atrocities one more time, I'm going to
lose it.

Less-jokingly, maybe someone has some oddly specific mixing things they
need it for (I know I do!).
---
 .../chemistry/machinery/chem_master.dm        | 15 +++++++++
 tgui/packages/tgui/interfaces/ChemMaster.tsx  | 32 ++++++++++++++++++-
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/code/modules/reagents/chemistry/machinery/chem_master.dm b/code/modules/reagents/chemistry/machinery/chem_master.dm
index a3a33ba7f8e..a5c83ed2519 100644
--- a/code/modules/reagents/chemistry/machinery/chem_master.dm
+++ b/code/modules/reagents/chemistry/machinery/chem_master.dm
@@ -32,6 +32,8 @@
 	var/printing_speed = 0.75 SECONDS
 	/// Amount of layers which printed pills will be coated in
 	var/pill_layers = 3
+	/// Current custom transfer amount
+	var/custom_transfer_amount = 15
 
 /obj/machinery/chem_master/Initialize(mapload)
 	create_reagents(100)
@@ -281,6 +283,7 @@
 	.["selectedPillDuration"] = pill_layers
 	var/obj/item/held_item = user.get_active_held_item()
 	.["hasBeakerInHand"] = held_item?.is_chem_container() || FALSE
+	.["customTransferAmount"] = custom_transfer_amount
 
 	//contents of source beaker
 	var/list/beaker_data = null
@@ -414,6 +417,18 @@
 
 			return TRUE
 
+		if("setCustomTransfer")
+			var/target = params["target"]
+			if(isnull(target))
+				return FALSE
+
+			target = text2num(target)
+			if(isnull(target))
+				return FALSE
+
+			custom_transfer_amount = clamp(target, 0, beaker.volume)
+			return TRUE
+
 		if("transfer")
 			if(is_printing)
 				say("The buffer is locked while printing.")
diff --git a/tgui/packages/tgui/interfaces/ChemMaster.tsx b/tgui/packages/tgui/interfaces/ChemMaster.tsx
index 35496244aab..0ca26f17425 100644
--- a/tgui/packages/tgui/interfaces/ChemMaster.tsx
+++ b/tgui/packages/tgui/interfaces/ChemMaster.tsx
@@ -53,6 +53,7 @@ type AnalyzableBeaker = {
 type Data = {
   categories: Category[];
   isPrinting: BooleanLike;
+  customTransferAmount: number;
   printingProgress: number;
   printingTotal: number;
   selectedPillDuration: number;
@@ -97,6 +98,7 @@ const ChemMasterContent = (props: {
   const { act, data } = useBackend<Data>();
   const {
     isPrinting,
+    customTransferAmount,
     printingProgress,
     printingTotal,
     selectedPillDuration,
@@ -127,6 +129,22 @@ const ChemMasterContent = (props: {
                 <AnimatedNumber value={beaker.currentVolume} initial={0} />
                 {` / ${beaker.maxVolume} units`}
               </Box>
+              <Box inline color="label" mr={2}>
+                <NumberInput
+                  width="55px"
+                  unit="u"
+                  step={5}
+                  stepPixelSize={3}
+                  value={customTransferAmount}
+                  minValue={0}
+                  maxValue={beaker.maxVolume}
+                  onChange={(value) =>
+                    act('setCustomTransfer', {
+                      target: value,
+                    })
+                  }
+                />
+              </Box>
               <Button icon="eject" onClick={() => act('eject')}>
                 Eject
               </Button>
@@ -324,7 +342,7 @@ type ReagentProps = {
 const ReagentEntry = (props: ReagentProps) => {
   const { data, act } = useBackend<Data>();
   const { chemical, transferTo, analyze } = props;
-  const { isPrinting } = data;
+  const { isPrinting, customTransferAmount } = data;
   return (
     <Table.Row key={chemical.ref}>
       <Table.Cell color="label">
@@ -369,6 +387,18 @@ const ReagentEntry = (props: ReagentProps) => {
         >
           10
         </Button>
+        <Button
+          disabled={isPrinting}
+          onClick={() =>
+            act('transfer', {
+              reagentRef: chemical.ref,
+              amount: customTransferAmount,
+              target: transferTo,
+            })
+          }
+        >
+          {customTransferAmount}
+        </Button>
         <Button
           disabled={isPrinting}
           onClick={() =>