Migration Pattern — Context

Pattern: Migration
Component: context.md
Version: 1.2 | Updated: 2026-07-29

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Purpose

Define the minimum evidence package required before the Migration pattern may start — and when to refuse to start.

Required before activation

• Phased plan with rollback owners
• Data class and access paths
• Parity/integrity checks defined
• Digest-pinned jobs and environments

Refuse to start when

• Irreversible drop scheduled without verify evidence
• No dual-write or shadow-read window when required by data class
• Write DB MCP enabled without SELECT-only start

Trust and data class

• Label segments as trusted, internal, or untrusted for Migration packs.
• Keep untrusted retrieval out of the Migration system channel.
• Migration MCP enablement follows data class in mcps.md.

Pack shape for Migration

1. Trigger / AC (human-owned)
2. Ranked evidence inside the Migration budget
3. Constraints and non-goals for this activation
4. Open questions (empty before irreversible Migration steps)

Related

• Context pattern when packing is itself the hard problem
• Prompt variable bindings
• Skills activation triggers

Changelog

• 1.2 (2026-07-29): Migration context gates (required/refuse) rewritten for this envelope.