fix: coalesce fragmented paste events over SSH (#305)

Some terminals (e.g., MobaXterm) fragment large pastes into multiple
bracketed paste sequences, causing premature submit when newlines
trigger the submit handler before the full paste is received.

This adds paste coalescing with a 100ms debounce to buffer consecutive
paste events and process them as a single paste operation. Submit is
blocked while paste coalescing is active to prevent partial submissions.

Author: b3nw

packages/opencode/src/cli/cmd/tui/component/prompt/index.tsx

@@ -58,6 +58,20 @@ export function Prompt(props: PromptProps) {
   let anchor: BoxRenderable
   let autocomplete: AutocompleteRef
 
+  // Paste coalescing: buffer rapid consecutive paste events (e.g., from MobaXterm
+  // which fragments large pastes into multiple bracketed paste sequences)
+  const pasteBuffer: { chunks: string[]; timer: Timer | null } = {
+    chunks: [],
+    timer: null,
+  }
+  const [isPasting, setIsPasting] = createSignal(false)
+  const PASTE_DEBOUNCE_MS = 100
+
+  // Cleanup paste timer on unmount
+  onCleanup(() => {
+    if (pasteBuffer.timer) clearTimeout(pasteBuffer.timer)
+  })
+
   const keybind = useKeybind()
   const local = useLocal()
   const sdk = useSDK()
@@ -488,6 +502,7 @@ export function Prompt(props: PromptProps) {
   async function submit() {
     if (props.disabled) return
     if (autocomplete?.visible) return
+    if (isPasting()) return // Block submit during paste coalescing
     if (!store.prompt.input) return
     const trimmed = store.prompt.input.trim()
     if (trimmed === "exit" || trimmed === "quit" || trimmed === ":q") {
@@ -688,6 +703,59 @@ export function Prompt(props: PromptProps) {
     return
   }
 
+  // Process a coalesced paste (called after debounce timer expires)
+  async function processCoalescedPaste(pastedContent: string) {
+    if (!pastedContent) {
+      command.trigger("prompt.paste")
+      return
+    }
+
+    // Check if pasted content is a file path
+    const filepath = pastedContent.replace(/^'+|'+$/g, "").replace(/\\ /g, " ")
+    const isUrl = /^(https?):\/\//.test(filepath)
+    if (!isUrl) {
+      try {
+        const file = Bun.file(filepath)
+        // Handle SVG as raw text content, not as base64 image
+        if (file.type === "image/svg+xml") {
+          const content = await file.text().catch(() => {})
+          if (content) {
+            pasteText(content, `[SVG: ${file.name ?? "image"}]`)
+            return
+          }
+        }
+        if (file.type.startsWith("image/")) {
+          const content = await file
+            .arrayBuffer()
+            .then((buffer) => Buffer.from(buffer).toString("base64"))
+            .catch(() => {})
+          if (content) {
+            await pasteImage({
+              filename: file.name,
+              mime: file.type,
+              content,
+            })
+            return
+          }
+        }
+      } catch {}
+    }
+
+    const lineCount = (pastedContent.match(/\n/g)?.length ?? 0) + 1
+    if ((lineCount >= 3 || pastedContent.length > 150) && !sync.data.config.experimental?.disable_paste_summary) {
+      pasteText(pastedContent, `[Pasted ~${lineCount} lines]`)
+      return
+    }
+
+    // Insert the text directly for small pastes
+    input.insertText(pastedContent)
+    setTimeout(() => {
+      input.getLayoutNode().markDirty()
+      input.gotoBufferEnd()
+      renderer.requestRender()
+    }, 0)
+  }
+
   const highlight = createMemo(() => {
     if (keybind.leader) return theme.border
     if (store.mode === "shell") return theme.primary
@@ -853,72 +921,36 @@ export function Prompt(props: PromptProps) {
                 }
               }}
               onSubmit={submit}
-              onPaste={async (event: PasteEvent) => {
-                if (props.disabled) {
-                  event.preventDefault()
-                  return
-                }
+              onPaste={(event: PasteEvent) => {
+                event.preventDefault()
+                if (props.disabled) return
 
                 // Normalize line endings at the boundary
                 // Windows ConPTY/Terminal often sends CR-only newlines in bracketed paste
                 // Replace CRLF first, then any remaining CR
                 const normalizedText = event.text.replace(/\r\n/g, "\n").replace(/\r/g, "\n")
-                const pastedContent = normalizedText.trim()
-                if (!pastedContent) {
-                  command.trigger("prompt.paste")
-                  return
-                }
 
-                // trim ' from the beginning and end of the pasted content. just
-                // ' and nothing else
-                const filepath = pastedContent.replace(/^'+|'+$/g, "").replace(/\\ /g, " ")
-                const isUrl = /^(https?):\/\//.test(filepath)
-                if (!isUrl) {
+                // Buffer the paste content for coalescing
+                // Some terminals (e.g., MobaXterm) fragment large pastes into multiple
+                // bracketed paste sequences, which would otherwise trigger premature submit
+                // Don't trim individual chunks - preserve inter-fragment whitespace
+                pasteBuffer.chunks.push(normalizedText)
+                setIsPasting(true)
+
+                // Reset the debounce timer
+                if (pasteBuffer.timer) clearTimeout(pasteBuffer.timer)
+                pasteBuffer.timer = setTimeout(async () => {
+                  // Coalesce all chunks and process
+                  const coalesced = pasteBuffer.chunks.join("").trim()
+                  pasteBuffer.chunks = []
+                  pasteBuffer.timer = null
                   try {
-                    const file = Bun.file(filepath)
-                    // Handle SVG as raw text content, not as base64 image
-                    if (file.type === "image/svg+xml") {
-                      event.preventDefault()
-                      const content = await file.text().catch(() => {})
-                      if (content) {
-                        pasteText(content, `[SVG: ${file.name ?? "image"}]`)
-                        return
-                      }
-                    }
-                    if (file.type.startsWith("image/")) {
-                      event.preventDefault()
-                      const content = await file
-                        .arrayBuffer()
-                        .then((buffer) => Buffer.from(buffer).toString("base64"))
-                        .catch(() => {})
-                      if (content) {
-                        await pasteImage({
-                          filename: file.name,
-                          mime: file.type,
-                          content,
-                        })
-                        return
-                      }
-                    }
-                  } catch {}
-                }
-
-                const lineCount = (pastedContent.match(/\n/g)?.length ?? 0) + 1
-                if (
-                  (lineCount >= 3 || pastedContent.length > 150) &&
-                  !sync.data.config.experimental?.disable_paste_summary
-                ) {
-                  event.preventDefault()
-                  pasteText(pastedContent, `[Pasted ~${lineCount} lines]`)
-                  return
-                }
-
-                // Force layout update and render for the pasted content
-                setTimeout(() => {
-                  input.getLayoutNode().markDirty()
-                  input.gotoBufferEnd()
-                  renderer.requestRender()
-                }, 0)
+                    await processCoalescedPaste(coalesced)
+                  } finally {
+                    // Only clear isPasting if no new paste arrived during processing
+                    if (!pasteBuffer.timer) setIsPasting(false)
+                  }
+                }, PASTE_DEBOUNCE_MS)
               }}
               ref={(r: TextareaRenderable) => {
                 input = r