Say what actually went wrong

Every failure produced the same reply: read the directions, and check your
context size. For a card Janitor truncated that was fair. For a request
shape the user never chose, or for a bug in sucker, it blamed them for
something they could not have done anything about — and sent them back to
directions they had already followed.

Failures that can be explained now explain themselves: no card in the
request, no greeting in the chat, a card that arrived truncated (which
keeps the context-size advice, since that is where it belongs), and a
request with nothing in it. Anything else is a bug nobody anticipated, so
the reply says as much, says it is not the user's fault, and asks them to
DM @lyseverian on Discord — an unexplained failure nobody reports never
gets fixed. Internals are never echoed back.

SuckerError is recognised by name as well as by identity, because Next can
bundle a module into more than one chunk and a mismatched class would
quietly send every explained error down the unknown-bug path.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NX2SsmUqQftWTZAY4BDuFa

src/lib/errors.ts

@@ -0,0 +1,71 @@
+/**
+ * Telling people what actually went wrong.
+ *
+ * Every failure used to produce one message: "You dingus, read the directions
+ * on sucker before trying again", with a note about context size. For a
+ * truncated card that was fair. For a request shape the user never chose, or
+ * for a bug in sucker, it blamed them for something they could not have done
+ * anything about — and told them to check directions they had already followed.
+ *
+ * So: anything thrown as a SuckerError is written for the person who hit it
+ * and is shown to them verbatim. Anything else is a bug nobody anticipated,
+ * and the reply says so and asks them to report it, because an unexplained
+ * failure that nobody hears about never gets fixed.
+ */
+
+/** Where to send someone when sucker is at fault. */
+export const CONTACT = "DM @lyseverian on Discord";
+
+export class SuckerError extends Error {
+  constructor(message: string) {
+    super(message);
+    this.name = "SuckerError";
+  }
+}
+
+/**
+ * `instanceof` is checked by name as well: Next can bundle the same module
+ * into more than one chunk, and a class identity that differs between them
+ * would quietly send every explained error down the "unknown bug" path.
+ */
+export function isSuckerError(error: unknown): error is SuckerError {
+  return (
+    error instanceof SuckerError ||
+    (typeof error === "object" &&
+      error !== null &&
+      (error as { name?: unknown }).name === "SuckerError")
+  );
+}
+
+export function userFacingMessage(error: unknown): string {
+  if (isSuckerError(error)) return error.message;
+  return (
+    "Something went wrong that sucker has no explanation for, and nothing was " +
+    `saved. This one is not your fault — please ${CONTACT} and say what you ` +
+    "were pulling, because unreported ones do not get fixed."
+  );
+}
+
+/** The card arrived without the markers sucker needs to read it. */
+export const TRUNCATED_CARD = new SuckerError(
+  "The card came through incomplete — the markers sucker looks for are not in " +
+    "it. That usually means the bot is larger than your context size and " +
+    "Janitor cut it short, so raise Context Size in Generation Settings and " +
+    `try again. If it is already generous, re-read the directions on sucker, and ${CONTACT} if it still will not go.`
+);
+
+export const NO_CARD = new SuckerError(
+  "There is no character card in that request — sucker could not find a " +
+    "system message in it. Point sucker at a chat with a bot in it, not an " +
+    "empty one, and try again."
+);
+
+export const NO_GREETING = new SuckerError(
+  "That chat has no message from the bot yet, so there is nothing to pull. " +
+    "Open the chat until the bot's first message shows, then send again."
+);
+
+export const TOO_FEW_MESSAGES = new SuckerError(
+  "That request barely had anything in it — sucker needs a chat with a bot " +
+    "and at least one message in it. Open the chat properly and try again."
+);