feat(tui): refine quiet terminal interactions

tui/src/composer-draft.ts

@@ -0,0 +1,44 @@
+const LARGE_PASTE_CHARS = 1_000
+const LARGE_PASTE_LINES = 10
+
+export interface PasteInsertion {
+  text: string
+  compacted: boolean
+  description: string
+}
+
+/** Keeps large pasted text out of the editor without changing what is sent. */
+export class ComposerDraft {
+  private readonly pastes = new Map<string, string>()
+
+  paste(value: string): PasteInsertion {
+    const text = value.replace(/\r\n/gu, "\n").replace(/\r/gu, "\n")
+    const lines = text.split("\n").length
+    if (text.length < LARGE_PASTE_CHARS && lines < LARGE_PASTE_LINES) {
+      return { text, compacted: false, description: "" }
+    }
+
+    const description = lines > 1 ? `${lines} lines` : `${text.length} characters`
+    const base = `[Pasted ${description}]`
+    let label = base
+    for (let index = 2; this.pastes.has(label); index += 1) label = `${base.slice(0, -1)} #${index}]`
+    this.pastes.set(label, text)
+    return { text: `${label} `, compacted: true, description }
+  }
+
+  expand(visible: string): string {
+    let expanded = visible
+    for (const [label, content] of this.pastes) expanded = expanded.split(label).join(content)
+    return expanded
+  }
+
+  prune(visible: string): void {
+    for (const label of this.pastes.keys()) {
+      if (!visible.includes(label)) this.pastes.delete(label)
+    }
+  }
+
+  clear(): void {
+    this.pastes.clear()
+  }
+}