Migration Pattern — Subagents

Pattern: Migration
Component: subagents.md
Version: 1.1 | Updated: 2026-07-16

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Subagent	Role	When invoked	Output
Consumer Inventory	Finds services, jobs, BI, partners using the surface	Start	Owned consumer table
Reconciler	Writes and runs count/semantic comparisons	Before cutover	Gate pass/fail + samples
Rollback Author	Specifies rollback per phase	During plan	Rollback steps + scripts refs

Consumer Inventory contract

• Include sync APIs, async consumers, batch jobs, reverse ETL, partner feeds
• Each row needs owner and “breakage mode”
• “Unknown” is not acceptable for High risk without explicit accept risk

Reconciler contract

• At least one global count check and one semantic sample check
• Thresholds numeric (e.g. mismatch < 0.01%)
• Fail closed: no cutover on red gates

Rollback Author contract

• Expand rollback: usually leave additive objects
• Dual rollback: stop dual-write; keep expand
• Cutover rollback: flip primary back
• Contract rollback: often impossible — mark PONR