# Two MSAs, one summary: missing document-boundary check merges contracts

## TL;DR
Hash every input document and tag each extracted clause with its document id, processing one contract per run. Without a boundary check, clauses from two MSAs with the same counterparty blend into a single summary that cites the wrong terms. Fail the run if one summary ever carries two document ids.

```text
summary cites "liability cap $500k" from MSA-2024.pdf inside the MSA-2026.pdf review - no document boundary enforced
```

1. Hash each input file and assign a document id before extraction starts.
   Expected: every document has a stable id in the run manifest.
2. Tag every extracted clause with its source document id.
   Expected: each clause record carries the id of the file it came from.
3. Process one document per extraction run. Never batch two MSAs into a single context.
   Expected: cross-document mixing becomes structurally impossible.
4. Assert a single document id per summary. If clauses with two ids land in one summary, fail loudly.
   Expected: a mixing bug stops the run instead of shipping a blended summary.

## Use this when
- a summary cites terms that belong to a different contract
- two documents from the same counterparty are processed together
- citations resolve to pages in the wrong file
- clause counts look doubled or terms contradict each other

## Not for this skill when
- the merge happened inside one document (amendment vs base text confusion)
- the two files are actually the same contract in different formats (a dedupe problem)
- you intentionally compare two contracts (use a diff workflow, not one summary)

## Variant phrasings
- agent merged two contracts into one summary
- clause extraction mixed up two MSAs same counterparty
- document boundary check missing contract review pipeline
- summary cites wrong contract terms blended

## Why it happens
Batching documents into one context window is faster and cheaper, so pipelines do it by default. The model has no reliable sense of file boundaries inside a flat text stream, especially when both documents share a counterparty, similar structure, and overlapping defined terms. The summary reads coherently, which is exactly why nobody catches it.

## Edge cases
- Filenames lie. Hash content, not names, for the document id.
- Amendments belong with their base contract; model the relationship explicitly instead of relying on batching.
- The assertion in step 4 needs the clause-level tags from step 2; summaries alone cannot be checked.
- Re-run both contracts separately after the fix. The blended summary is untrustworthy.

## Provenance

Resolved from the public thread: https://vectle.com/posts/pst_TuRbaXvXsg6XnAvq4hEecA