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 vaquarkhan/data-engineering-agent-skills --skill schema-evolution-and-contract-migrationsgit clone --depth 1 https://github.com/vaquarkhan/data-engineering-agent-skillsWrote 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/vaquarkhan/data-engineering-agent-skills/schema-evolution-and-contract-migrations)<a href="https://agentmods.dev/skills/vaquarkhan/data-engineering-agent-skills/schema-evolution-and-contract-migrations"><img src="https://agentmods.dev/badge/skills/vaquarkhan/data-engineering-agent-skills/schema-evolution-and-contract-migrations/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/vaquarkhan/data-engineering-agent-skills/schema-evolution-and-contract-migrations"><img src="https://agentmods.dev/badge/skills/vaquarkhan/data-engineering-agent-skills/schema-evolution-and-contract-migrations.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 | $0.00045 | $0.00461 |
| Opus 5 | $0.00023 | $0.00230 |
| Sonnet 5 | $0.00009 | $0.00092 |
| Haiku 4.5 | $0.00005 | $0.00046 |
Grade A, and why
schema-evolution-and-contract-migrations 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 9d 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.
What it actually says
Schema Evolution And Contract Migrations
Overview
Use this skill when a schema change can ripple through pipelines, models, dashboards, or external consumers. It helps agents make schema evolution deliberate, compatible, and recoverable.
When to Use
- changing input or output schemas
- renaming or dropping columns
- changing data types or nullability
- adding keys or changing grain
- migrating consumers from an old contract to a new one
Do not treat schema changes as isolated SQL edits. They are compatibility events.
Workflow
-
Classify the change. Decide whether it is:
- additive
- backward compatible
- breaking
- temporary dual-schema support
-
Map consumers and blast radius. Include:
- upstream producers
- downstream models
- dashboards
- APIs or extracts
- external consumers
-
Create the migration path. Options may include:
- dual writes
- compatibility views
- phased deprecation
- explicit consumer cutover windows
-
Validate old and new contracts during the transition.
-
Remove deprecated paths only after confirmation that consumers moved.
Common Rationalizations
| Rationalization | Reality |
|---|---|
| "It is just a column rename." | Renames break dashboards, notebooks, and joins that depend on the old name. |
| "Consumers will update quickly." | Some consumers are undocumented or owned by other teams. |
| "Additive changes are always safe." | New columns can still change file contracts, schemas, and downstream assumptions. |
Red Flags
- no consumer inventory exists
- breaking changes ship without transition support
- type changes are made without data validation
- deprecation timing is based on hope instead of confirmation
Verification
- The change type and compatibility level are classified
- Consumers and blast radius are identified
- A migration and rollback path exists
- Old and new contract behavior are validated during transition
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.
- 9d ago First seen · 71 lines · 45 tokens per session scan A e969df538aa0
schema-evolution-and-contract-migrations is a skill published in the GitHub repository vaquarkhan/data-engineering-agent-skills (45 stars, last pushed 3mo ago), licensed MIT. It adds 45 tokens to every session and 461 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 2026-09-03.
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