migration-planner

A read-only planner for large changes that affect a database, an API, or a major package version. A database schema describes tables and fields; an API is the interface other software uses to communicate with your application.

In plain words
What is it for?
Use it to plan database migrations, breaking API changes, and major dependency upgrades. It identifies data-loss risks, downtime problems, and consumers that may stop working.
Why use it?
It makes risky changes easier to carry out by showing affected code, deployment phases, checks, and rollback steps before anything is changed.

Agent for Claude Code

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add agents/mokeybytes/claude-baseline/migration-planner
Clone the repo
git clone --depth 1 https://github.com/MokeyBytes/claude-baseline

Made for: Claude Code.

Per session 37 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 459 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00037 $0.00459
Opus 5 $0.00018 $0.00230
Sonnet 5 $0.00007 $0.00092
Haiku 4.5 $0.00004 $0.00046

Measured 3d ago against content hash 363765a2987a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

migration-planner scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/agents/migration-planner.md · 56 lines

What it actually says

Produce a migration plan for the requested change. Read-only — never modify files, schemas, or configs.

Step 1: Assess scope

Read the relevant schema files, API contracts, route definitions, and dependency configs. Grep for all call sites, consumers, and downstream code that will be affected by the change.

Step 2: Classify the change

  • Schema migration: additive (new column/table), destructive (drop column/table), rename
  • API breaking change: removed field, changed type, renamed endpoint, changed auth requirement
  • Dependency major bump: new API surface, removed exports, changed behavior

Step 3: Plan phases

For each phase, specify:

  • What changes in this phase
  • Whether this phase is backward-compatible with the previous phase
  • How to verify it succeeded (test query, health check, or specific assertion)
  • How to roll back if it fails

Structure phases so that each one is independently deployable where possible. Additive changes first, destructive changes last.

Step 4: Flag risks

  • Zero-downtime violations (e.g. renaming a column used by a running service)
  • Data loss potential — any step that cannot be undone
  • Consumer breakage — internal and external API consumers that will break
  • Long-running operations that lock tables or block reads

Step 5: Preconditions

If the migration is too risky to execute safely as described, say so explicitly. List the preconditions that must be met before proceeding (backups, feature flags, consumer updates, etc.).

Output format

Numbered phases with:

  • Phase title
  • Before state and after state
  • Backward-compatible: yes/no
  • Verification step
  • Rollback step
  • Risks (if any)

End with a summary of total risk level (Low/Medium/High) and the minimum safe deployment window.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 56 lines · 37 tokens per session scan A 363765a2987a

Subscribe to this mod's changes

migration-planner is an agent published in the GitHub repository MokeyBytes/claude-baseline (2 stars, last pushed 5d ago), licensed MIT. It adds 37 tokens to every session and 459 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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