From 4815d28aa49af422320b21c42d509b31e6123af2 Mon Sep 17 00:00:00 2001
From: Cadence Ember <cadence@disroot.org>
Date: Wed, 13 May 2026 14:38:14 +1200
Subject: [PATCH] Code blocks uploaded as attachments when too long

---
 src/m2d/converters/event-to-message.js      |  4 ++-
 src/m2d/converters/event-to-message.test.js | 32 +++++++++++++++++++++
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/src/m2d/converters/event-to-message.js b/src/m2d/converters/event-to-message.js
index 31caef0..fd00827 100644
--- a/src/m2d/converters/event-to-message.js
+++ b/src/m2d/converters/event-to-message.js
@@ -892,7 +892,9 @@ async function eventToMessage(event, guild, channel, di) {
 						}
 						// Check for incompatible backticks in code blocks
 						let preNode
-						if (node.nodeType === 3 && node.nodeValue.includes("```") && (preNode = nodeIsChildOf(node, ["PRE"]))) {
+						let isBackticksTextInPre = node.nodeType === 3 && node.nodeValue.includes("```") && (preNode = nodeIsChildOf(node, ["PRE"]))
+						let isLongPre = node.tagName === "PRE" && node.textContent.length > 1800 && (preNode = node)
+						if (isBackticksTextInPre || isLongPre) {
 							if (preNode.firstChild?.nodeName === "CODE") {
 								let ext = preNode.firstChild.className.match(/language-(\S+)/)?.[1]
 								if (!dUtils.supportedPlaintextPreviewExtensions.has(ext)) ext = "txt"
diff --git a/src/m2d/converters/event-to-message.test.js b/src/m2d/converters/event-to-message.test.js
index 68d519a..70b53d3 100644
--- a/src/m2d/converters/event-to-message.test.js
+++ b/src/m2d/converters/event-to-message.test.js
@@ -1219,6 +1219,38 @@ test("event2message: code blocks are uploaded as attachments instead if they con
 	)
 })
 
+test("event2message: code blocks are uploaded as attachments instead if they are really long", async t => {
+	t.deepEqual(
+		await eventToMessage({
+			type: "m.room.message",
+			sender: "@cadence:cadence.moe",
+			content: {
+				msgtype: "m.text",
+				body: "wrong body",
+				format: "org.matrix.custom.html",
+				formatted_body: `So if you run code like this<pre><code class="language-js">${"A".repeat(2000)}</code></pre>it should print a markdown formatted code block`
+			},
+			event_id: "$pGkWQuGVmrPNByrFELxhzI6MCBgJecr5I2J3z88Gc2s",
+			room_id: "!kLRqKKUQXcibIMtOpl:cadence.moe"
+		}),
+		{
+			ensureJoined: [],
+			messagesToDelete: [],
+			messagesToEdit: [],
+			messagesToSend: [{
+				username: "cadence [they]",
+				content: "So if you run code like this `[inline_code.js]` it should print a markdown formatted code block",
+				attachments: [{id: "0", filename: "inline_code.js"}],
+				pendingFiles: [{name: "inline_code.js", buffer: Buffer.from("A".repeat(2000))}],
+				avatar_url: undefined,
+				allowed_mentions: {
+					parse: ["users", "roles"]
+				}
+			}]
+		}
+	)
+})
+
 test("event2message: characters are encoded properly in code blocks", async t => {
 	t.deepEqual(
 		await eventToMessage({