fix(cron): send a paste-mode prompt's Enter as its own write

A cron job in "Paste (direct)" input mode wrote `<text>\r` into the pane
in one piece. Claude Code (measured on 2.1.283) takes a burst of about a
hundred characters as a paste, so the `\r` landed as a newline and the
prompt sat unsent on the composer while the run reported `prompt_sent`.

Delivery now lives in `deliverCronPrompt()`. Paste mode writes the text
raw, waits CRON_PASTE_ENTER_DELAY_MS (300 ms), sends `\r` as a separate
write down the same PTY (so it cannot overtake the text), and arms the
session's composer check through the new public
`Session.verifySubmitted()`, which re-presses Enter while the prompt is
still visibly unsent. A session with nothing to write to now fails the
run instead of reporting the prompt as sent. Typed mode is unchanged.

Verified on an isolated instance: a paste-mode job with a 104-character
prompt submitted on the first Enter and Claude answered.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/config/server-timing.ts

@@ -99,3 +99,11 @@ export const STALE_DATA_MAX_AGE_MS = 60 * 60 * 1000;
 
 /** Standard 5-minute inactivity timeout for streams and caches (ms) */
 export const INACTIVITY_TIMEOUT_MS = 5 * 60 * 1000;
+
+/**
+ * Gap between a paste-mode cron prompt's text and its Enter (ms). The two must be
+ * separate writes: Claude Code takes a raw `<text>\r` burst of about a hundred
+ * characters as a paste and turns its `\r` into a newline. A separate `\r` 80 ms
+ * after the text was measured to submit; this leaves room for a longer prompt.
+ */
+export const CRON_PASTE_ENTER_DELAY_MS = 300;

src/cron/cron-service.ts

@@ -20,7 +20,7 @@ import { getErrorMessage, createErrorResponse, ApiErrorCode } from '../types/api
 import { MAX_CONCURRENT_SESSIONS, MAX_CRON_JOBS, MAX_CRON_RUN_HISTORY } from '../config/map-limits.js';
 import { canUsernameRunPrivilegedCommands, resolveClaudeModeForUsername } from '../user-store.js';
 import { sessionCapacityState, isWorkingDirAllowedForUsername } from '../web/route-helpers.js';
-import { CRON_READY_MAX_ATTEMPTS, CRON_READY_SETTLE_MS } from '../config/server-timing.js';
+import { CRON_PASTE_ENTER_DELAY_MS, CRON_READY_MAX_ATTEMPTS, CRON_READY_SETTLE_MS } from '../config/server-timing.js';
 import {
   DEFAULT_BLOCKED_TREES,
   isBlockedAttachmentPath,
@@ -100,6 +100,41 @@ const CRON_WORKING_DIR_BLOCKED_TREES: readonly string[] = [...DEFAULT_BLOCKED_TR
 /** Prompt delivery is single-line only (writeViaMux/Ink constraint). */
 const HAS_NEWLINE = /[\r\n]/;
 
+/** The three session calls prompt delivery needs, so it can be tested without a PTY. */
+type CronPromptTarget = Pick<Session, 'write' | 'writeViaMux' | 'verifySubmitted'>;
+
+/**
+ * Send a cron job's (single-line) prompt into its session and press Enter.
+ *
+ * `typed` goes through the mux: the text is typed, Enter is its own key, and the
+ * session re-presses it while the prompt is still on the composer.
+ *
+ * `paste` writes the text straight into the PTY, and must send its Enter as a
+ * SEPARATE write. It used to send `<text>\r` in one piece, and Claude Code (measured
+ * on 2.1.283) takes a burst of about a hundred characters as a paste, so the `\r`
+ * landed as a newline and the prompt sat unsent while the run reported
+ * `prompt_sent`. The Enter goes down the same PTY as the text, so it cannot overtake
+ * it, and the same composer check then covers a CLI that was not taking Enter yet.
+ *
+ * @returns false when the session had no PTY or mux to write to
+ */
+export async function deliverCronPrompt(
+  target: CronPromptTarget,
+  prompt: string,
+  inputMode: CronJob['inputMode'],
+  wait: (ms: number) => Promise<void> = delay
+): Promise<boolean> {
+  if (inputMode !== 'paste') {
+    return target.writeViaMux(prompt.endsWith('\r') ? prompt : `${prompt}\r`);
+  }
+  const text = prompt.replace(/[\r\n]+$/, '');
+  if (!target.write(text)) return false;
+  await wait(CRON_PASTE_ENTER_DELAY_MS);
+  if (!target.write('\r')) return false;
+  target.verifySubmitted(text);
+  return true;
+}
+
 /** Order-insensitive equality for the weekly-days arrays. */
 function sameDays(a: number[] | undefined, b: number[] | undefined): boolean {
   const x = [...(a ?? [])].sort((p, q) => p - q);
@@ -623,15 +658,9 @@ export class CronService {
         const s = this.deps.sessions.get(sessionId);
         if (!s) return;
         try {
-          const payload = prompt.endsWith('\r') ? prompt : `${prompt}\r`;
-          let delivered = true;
-          if (job.inputMode === 'paste') {
-            s.write(payload);
-          } else {
-            delivered = await s.writeViaMux(payload);
-          }
+          const delivered = await deliverCronPrompt(s, prompt, job.inputMode);
           if (!delivered) {
-            this.failRun(job, run, 'Failed to send prompt: mux write failed');
+            this.failRun(job, run, 'Failed to send prompt: the session could not be written to');
             return;
           }
           run.status = 'prompt_sent';

src/session.ts

@@ -4207,6 +4207,16 @@ export class Session extends EventEmitter {
     return false;
   }
 
+  /**
+   * Arm the composer check for a prompt that went out some other way than
+   * `writeViaMux`, e.g. cron's paste mode, which writes the body raw and its Enter
+   * separately. `text` is what the composer line starts with while the prompt is still
+   * unsent; the check re-presses Enter only while that holds.
+   */
+  verifySubmitted(text: string): void {
+    this._verifySubmitted(`${text}\r`);
+  }
+
   /**
    * Arm the composer check for a write that carried Enter (session-submit-verifier.ts):
    * Claude Code 2.1.277+ ignores Enter for the first 30-50 s after the composer paints,