Root-cause a break
Given a single break row (key, GL values, subledger values, bucket, likely cause), trace it to source and produce a root-cause statement.
Trace path
- Pull the GL side — via the internal-gl MCP, fetch the journal entry or posting that produced this GL line: entry id, posting date, source system, batch id, preparer.
- Pull the subledger side — via the subledger MCP, fetch the matching transaction: trade id, trade/settle dates, counterparty, source feed, FX rate used.
- Diff the attributes — line up posting date, FX rate/date, account mapping, quantity sign, amount sign. The differing attribute is usually the cause.
Cause → statement
Write the root cause as a single sentence in the form "⟨side⟩ ⟨did what⟩ because ⟨reason⟩", e.g.:
- "GL posted on settle date (T+2) while subledger posted on trade date — timing break, will clear on 2026-05-07."
- "Subledger used WM/R 4pm rate; GL used Bloomberg close — FX break of 12 bps on the base amount."
- "Security ABC123 maps to GL account 11420 in the mapping table but the subledger fed 11410 — mapping break, raise to reference-data."
- "Subledger posted the trade twice (trade ids 88412 and 88419 are duplicates) — duplicate post, suppress 88419."
Output
For each traced break, return:
{
"key": "...",
"root_cause": "one sentence as above",
"owner": "ops | reference-data | accounting | upstream-system",
"expected_clear_date": "YYYY-MM-DD or null",
"action": "monitor | adjust | raise-ticket | suppress"
}
Only the resolver writes adjustments — this skill diagnoses, it does not post.