feat: configurable outbound text chunk limits

src/auto-reply/chunk.test.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from "vitest";
 
-import { chunkText } from "./chunk.js";
+import { chunkText, resolveTextChunkLimit } from "./chunk.js";
 
 describe("chunkText", () => {
   it("keeps multi-line text in one chunk when under limit", () => {
@@ -45,3 +45,30 @@ describe("chunkText", () => {
     expect(chunks).toEqual(["Supercalif", "ragilistic", "expialidoc", "ious"]);
   });
 });
+
+describe("resolveTextChunkLimit", () => {
+  it("uses per-surface defaults", () => {
+    expect(resolveTextChunkLimit(undefined, "whatsapp")).toBe(4000);
+    expect(resolveTextChunkLimit(undefined, "telegram")).toBe(4000);
+    expect(resolveTextChunkLimit(undefined, "signal")).toBe(4000);
+    expect(resolveTextChunkLimit(undefined, "imessage")).toBe(4000);
+    expect(resolveTextChunkLimit(undefined, "discord")).toBe(2000);
+  });
+
+  it("supports a global override", () => {
+    const cfg = { messages: { textChunkLimit: 1234 } };
+    expect(resolveTextChunkLimit(cfg, "whatsapp")).toBe(1234);
+    expect(resolveTextChunkLimit(cfg, "discord")).toBe(1234);
+  });
+
+  it("prefers per-surface overrides over global", () => {
+    const cfg = {
+      messages: {
+        textChunkLimit: 1234,
+        textChunkLimitBySurface: { discord: 111 },
+      },
+    };
+    expect(resolveTextChunkLimit(cfg, "discord")).toBe(111);
+    expect(resolveTextChunkLimit(cfg, "telegram")).toBe(1234);
+  });
+});

src/auto-reply/chunk.ts

@@ -2,6 +2,43 @@
 // unintentionally breaking on newlines. Using [\s\S] keeps newlines inside
 // the chunk so messages are only split when they truly exceed the limit.
 
+import type { ClawdisConfig } from "../config/config.js";
+
+export type TextChunkSurface =
+  | "whatsapp"
+  | "telegram"
+  | "discord"
+  | "signal"
+  | "imessage"
+  | "webchat";
+
+const DEFAULT_CHUNK_LIMIT_BY_SURFACE: Record<TextChunkSurface, number> = {
+  whatsapp: 4000,
+  telegram: 4000,
+  discord: 2000,
+  signal: 4000,
+  imessage: 4000,
+  webchat: 4000,
+};
+
+export function resolveTextChunkLimit(
+  cfg: Pick<ClawdisConfig, "messages"> | undefined,
+  surface?: TextChunkSurface,
+): number {
+  const surfaceOverride = surface
+    ? cfg?.messages?.textChunkLimitBySurface?.[surface]
+    : undefined;
+  if (typeof surfaceOverride === "number" && surfaceOverride > 0) {
+    return surfaceOverride;
+  }
+  const globalOverride = cfg?.messages?.textChunkLimit;
+  if (typeof globalOverride === "number" && globalOverride > 0) {
+    return globalOverride;
+  }
+  if (surface) return DEFAULT_CHUNK_LIMIT_BY_SURFACE[surface];
+  return 4000;
+}
+
 export function chunkText(text: string, limit: number): string[] {
   if (!text) return [];
   if (limit <= 0) return [text];