---
name: historic_sql_patterns
description: Identify recurring cross-table historic-SQL analytical intents from a bounded pattern shard and emit typed pattern evidence for deterministic wiki projection.
callers: [memory_agent]
---
# Historic SQL Patterns
Use this skill when the WorkUnit raw file is a `patterns-input/part-0001.json` style shard from the `historic-sql` adapter. Older staged bundles may still provide root `patterns-input.json`; when that is the WorkUnit raw file, read it the same way.
## Required Workflow
1. Read the WorkUnit notes first.
2. Find the single pattern input file listed under the WorkUnit `rawFiles` section.
3. Call `read_raw_file` for that exact raw file path.
4. Identify recurring analytical intents that span at least two tables and have repeated usage signal.
5. Emit one `pattern` evidence object per durable cross-table intent by calling `emit_historic_sql_evidence`.
6. Stop after all pattern evidence has been emitted.
Every join column mentioned in pattern descriptions must be verified via
entity_details for both sides of the join.
## Identifier Verification Protocol
Before writing a wiki page or SL source on any topic:
1. `discover_data({query: "<topic>"})` - see what wikis, SL sources, and raw
tables already exist. Prefer updating existing pages over creating new ones.
Before emitting any `schema.table` or `schema.table.column` into a wiki body,
SL source, `tables:` frontmatter, `sl_refs`, or `emit_unmapped_fallback`:
2. `entity_details({connectionId, targets: [{display: "<identifier>"}]})` -
confirm the identifier resolves; inspect native types, FK/PK, and
sampleValues.
3. For literal values from the source, such as status codes or plan tiers,
check whether they appear in `entity_details` sampleValues for the relevant
column. If sampleValues is short or the sample may have missed real values,
run a `sql_execution` probe with the same warehouse connection id:
`sql_execution({connectionId, sql: "SELECT DISTINCT <col> FROM <ref> LIMIT 50"})`.
4. If the candidate identifier still does not resolve, do one of:
- Use `sql_execution({connectionId, sql: "SELECT 1 FROM <ref> LIMIT 0"})`.
If it errors, the identifier is fictional.
- Wrap the identifier in `[unverified - from <rawPath>]` in the wiki body,
citing the exact raw path that mentioned it.
- When recording `emit_unmapped_fallback` with `no_physical_table`, include
the failing probe error in `clarification`.
5. Never copy `<schema>.<table>` placeholder strings from these instructions
into output.
## Evidence Shape
Each call to `emit_historic_sql_evidence` must use this shape:
```json
{
"kind": "pattern",
"pattern": {
"slug": "order-lifecycle-analysis",
"title": "Order Lifecycle Analysis",
"narrative": "Analysts compare order statuses with customer segments to understand lifecycle movement.",
"definitionSql": "select o.status, count(*) from public.orders o join public.customers c on c.id = o.customer_id group by o.status",
"tablesInvolved": ["public.orders", "public.customers"],
"slRefs": ["orders", "customers"],
"constituentTemplateIds": ["pg:1", "pg:2"]
}
}
```
The `pattern` object must match `patternOutputSchema`; multiple calls together must form `patternsArraySchema`.
## Pattern Selection Rules
- Prefer patterns that involve two or more tables.
- Prefer templates with `executionsBucket` at least `10-100` and `distinctUsersBucket` above solo usage.
- Merge templates into one pattern only when the business intent is the same.
- Use a stable kebab-case slug based on intent, not a template id.
- Set `definitionSql` to the clearest representative SQL from a constituent template.
- Set `slRefs` to source names when the source name is obvious from table names; omit uncertain refs rather than guessing.
- Treat each pattern shard independently; do not read peer shard files from `peerFileIndex`.
## Boundaries
- Do not call wiki_write.
- Do not call sl_write_source.
- Do not call sl_edit_source.
- Do not call context_candidate_write.
- Do not create single-table pattern pages.
- Do not copy credentials, tokens, user emails, or unredacted literals into evidence.