src/plugins/agents/base.ts (1)

147-180: Duplicate implementation of appendWithCharLimit — extract to a shared utility.

This function is duplicated verbatim in src/engine/index.ts (lines 92–125). Both copies share the same algorithm and signature. If a bug is found or the truncation logic changes, both sites must be updated in lockstep.

Consider extracting it into a shared module (e.g., src/utils/string-limits.ts) and importing it in both base.ts and engine/index.ts, each supplying its own constants and prefix.

♻️ Proposed shared utility

Create a new file src/utils/string-limits.ts:

/**
 * ABOUTME: Shared helper for capping in-memory string buffers while preserving tail content.
 */

/**
 * Append chunk data while enforcing an in-memory size cap.
 * Keeps the most recent content (tail) to preserve completion markers near the end.
 */
export function appendWithCharLimit(
  current: string,
  chunk: string,
  maxChars: number,
  prefix: string
): string {
  if (!chunk) return current;
  if (maxChars <= 0) return '';

  const totalLen = current.length + chunk.length;
  if (totalLen <= maxChars) {
    return current + chunk;
  }

  if (maxChars <= prefix.length) {
    return prefix.slice(0, maxChars);
  }

  const keep = maxChars - prefix.length;
  const combinedTailStart = totalLen - keep;

  let tail: string;
  if (combinedTailStart >= current.length) {
    const startInChunk = combinedTailStart - current.length;
    tail = chunk.slice(startInChunk);
  } else {
    const tailFromCurrent = current.slice(combinedTailStart);
    const remaining = keep - tailFromCurrent.length;
    const tailFromChunk = remaining > 0 ? chunk.slice(-remaining) : '';
    tail = tailFromCurrent + tailFromChunk;
  }

  return prefix + tail;
}

Then in both base.ts and engine/index.ts:

-function appendWithCharLimit(
-  current: string,
-  chunk: string,
-  maxChars: number,
-  prefix = STREAM_TRUNCATED_PREFIX
-): string {
-  // ... duplicated body ...
-}
+import { appendWithCharLimit } from '../../utils/string-limits.js';

src/engine/index.ts (2)

1020-1044: A write failure on one stream disables both raw output streams.

If writeSync to stdout fails, both rawStdoutFilePath and rawStderrFilePath are set to undefined, losing the stderr raw capture as well (and vice-versa). This is probably intentional as a defensive measure (shared temp directory likely broken), but worth a brief inline comment to clarify intent.

---

75-129: Extract appendWithCharLimit to a shared utility module.

The function is defined identically in both src/engine/index.ts (line 96) and src/plugins/agents/base.ts (line 147), differing only in the default prefix parameter. This duplication risks divergence and violates DRY principles. Extract it into a shared utility module (e.g. src/utils/buffer.ts) and import from both locations, passing the context-specific prefix strings as needed.