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.
npx skills add wyattowalsh/agents --skill schema-evolution-plannergit clone --depth 1 https://github.com/wyattowalsh/agentsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/wyattowalsh/agents/schema-evolution-planner)<a href="https://agentmods.dev/skills/wyattowalsh/agents/schema-evolution-planner"><img src="https://agentmods.dev/badge/skills/wyattowalsh/agents/schema-evolution-planner/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/wyattowalsh/agents/schema-evolution-planner"><img src="https://agentmods.dev/badge/skills/wyattowalsh/agents/schema-evolution-planner.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00040 | $0.01825 |
| Opus 5.5 | $0.00016 | $0.00730 |
| Sonnet 5.5 | $0.00008 | $0.00365 |
| Haiku 4.5 | $0.00004 | $0.00183 |
Grade A, and why
schema-evolution-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 1mo 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.
How it starts
The opening of the file, as written. The whole thing — 167 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Schema Evolution Planner
Plan safe, staged database schema changes across application code, backfills, and cutovers.
Scope: Expand-contract and compatibility planning for live systems. NOT for greenfield schema design (database-architect) or DBA operations.
Canonical Vocabulary
| Term | Definition |
|---|---|
| expand | Additive schema change compatible with existing code |
| backfill | Data migration that populates new structures from old data |
| dual-write | Temporarily writing old and new representations |
| dual-read | Temporarily reading from both old and new representations |
| cutover | The point where traffic or logic switches to the new path |
| contract | Removal of deprecated schema after compatibility window closes |
| compatibility window | Period where old and new code must both work |
| invariant | Condition that must remain true during migration |
| shadow column | New field added beside the old field during migration |
| rollback point | Last safe state that can be restored without data loss |
Dispatch
| $ARGUMENTS | Mode |
|---|---|
plan <change> |
Build the full migration sequence |
review <migration or rollout> |
Audit an existing evolution plan |
backfill <change> |
Design the data backfill strategy |
cutover <change> |
Plan read or write switchover |
deprecate <change> |
Plan the contract and removal stage |
| Natural language about zero-downtime schema changes | Auto-detect the closest mode |
| Empty | Show the mode menu with examples |
Mode Menu
| # | Mode | Example |
|---|---|---|
| 1 | Plan | plan rename users.username to handle |
| 2 | Review | review migration plan for orders status enum change |
| 3 | Backfill | backfill new account_id on invoices |
| 4 | Cutover | cutover reads to new customer_profile table |
| 5 | Deprecate | deprecate legacy address columns |
When to Use
- Renaming columns or tables in a live system
- Splitting or merging tables without downtime
- Adding required fields to existing tables
- Introducing new identifiers or foreign keys gradually
- Coordinating schema changes with multiple application deploys
What ships with it
13 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
- evals/evals.json 4.8 KB
- references/change-type-decision-matrix.md 3.8 KB
- references/migration-failure-modes.md 3.3 KB
- references/output-templates.md 1.5 KB
- references/sample-rollout-sequences.md 2.5 KB
- scripts/asset_toolkit/__init__.py 303 B runs code
- scripts/asset_toolkit/_shared.py 5.6 KB runs code
- scripts/asset_toolkit/common.py 3.0 KB runs code
- scripts/asset_toolkit/package.py 43 KB runs code
- scripts/asset_toolkit/validate_evals.py 11 KB runs code
- scripts/asset_toolkit/validate_hooks.py 13 KB runs code
- scripts/asset_toolkit/validate_skill.py 3.6 KB runs code
- scripts/check.py 2.2 KB runs code
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.
- 1mo ago First seen · 167 lines · 40 tokens per session scan A d30b44a2c677
schema-evolution-planner is a skill published in the GitHub repository wyattowalsh/agents (5 stars, last pushed 1mo ago), licensed MIT. It adds 40 tokens to every session and 1,825 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-09-03.
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