Improvement: no retry/fallback strategy when grep returns zero results

[Augustas11]

Problem

The prompt has no explicit fallback instruction for zero-result grep searches. If grep returns nothing, the agent may hallucinate data, give up, or write an empty answer. There is no structured recovery path.

Suggested Fix

Add a fallback ladder to the WORKFLOW section:

If grep returns no results:
  1. Try alternate spellings and abbreviations (e.g. "pub debt" vs "public debt")
  2. Try searching index.txt for the relevant bulletin filename directly
  3. Try a broader term (drop qualifiers, search for the root noun only)
  4. Only if all three fail: state "Data not found in corpus" and write 0 to answer.txt

Impact

Medium — zero-result grep is a common failure mode for OCR-corrupted pre-1996 files and uncommon metric names. A structured fallback would recover several of the 43 always-fail questions.