synthetic-seeder

synthetic-seeder is a skill for Claude Code from sfc-gh-dflippo/snowflake-dbt-demo. It costs 88 tokens per session (4,632 once invoked), scanned A, original, Apache-2.0.

A generator for synthetic test cases for migrated stored procedures and functions. It reads the source SQL to find branches, null cases, and boundary values, then writes tests that can run against both the source and Snowflake versions.

In plain words
What is it for?
It creates step-by-step YAML tests for inserting data, calling routines, reading tables or outputs, and validating results.
Why use it?
It avoids using the converted code as its own reference, which could allow the same mistake to pass on both sides.

Skill for Claude Code

Written for Claude Code: installed under .claude/. Also seen: mentions subagents.

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is **YAML schema reference.** See [`../../references/step-based-yaml.md`](../../references/step-based-yaml.md) for the step types (SQL Query / Output Parameter / T.

Part of the snowflake-migration plugin — 72 skills, 7 agents shipped together

Good fit It creates step-by-step YAML tests for inserting data, calling routines, reading tables or outputs, and validating results.

Compare 6 skills from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/sfc-gh-dflippo/snowflake-dbt-demo
agentmods
npx agentmods add skills/sfc-gh-dflippo/snowflake-dbt-demo/synthetic-seeder

Made for: Claude Code.

Or install snowflake-migration, the plugin that ships this one along with the rest of its 72 skills, 7 agents.

Wrote 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.

agentmods badge for synthetic-seeder

README.md
[![agentmods](https://agentmods.dev/badge/skills/sfc-gh-dflippo/snowflake-dbt-demo/synthetic-seeder/github.svg)](https://agentmods.dev/skills/sfc-gh-dflippo/snowflake-dbt-demo/synthetic-seeder)
Your own site
<a href="https://agentmods.dev/skills/sfc-gh-dflippo/snowflake-dbt-demo/synthetic-seeder"><img src="https://agentmods.dev/badge/skills/sfc-gh-dflippo/snowflake-dbt-demo/synthetic-seeder/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.

agentmods 80×15 button for synthetic-seeder

Your own site · 80×15
<a href="https://agentmods.dev/skills/sfc-gh-dflippo/snowflake-dbt-demo/synthetic-seeder"><img src="https://agentmods.dev/badge/skills/sfc-gh-dflippo/snowflake-dbt-demo/synthetic-seeder.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 88 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,632 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00088 $0.04632
Opus 5 $0.00044 $0.02316
Sonnet 5 $0.00018 $0.00926
Haiku 4.5 $0.00009 $0.00463

Measured 2d ago against content hash 7d8381422b6f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

synthetic-seeder 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 2d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (enrich_yamls.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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/skills/snowflake-migration/skills/migration/migrate-objects/baseline-capture/synthetic-seeder/SKILL.md · 415 lines

How it starts

The opening of the file, as written. The whole thing — 415 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Synthetic Seeder Skill

Generate two-sided synthetic data tests for migrated stored procedures and functions. Tests are derived from source SQL analysis — the source is the oracle, not the converted code. Each test is a step-based YAML artifact directly consumable by scai test capture and scai test validate.

YAML schema reference. See ../../references/step-based-yaml.md for the step types (SQL Query / Output Parameter / Table Read / Cursor Read), the validate: true | false | [list] semantics, and the modifies_data / affected_tables inference rules. This file describes what to generate for each procedure; the cheat sheet is the source of truth for the shape of each step. For special cases (multi-RS, OUT params, cursor reads, before/after capture) see ../../migrate-object/EDIT_TEST_YAML.md.

Autonomous mode: When spawned as a subagent, skip interactive stopping points, apply reasonable defaults, document assumptions in the completion report, and send a send_message to main when done.


Scope and Boundaries

This skill does:

  • Analyze source SQL to identify branches, NULL paths, boundary values
  • Generate two-sided INSERT / CALL / SELECT steps in both source and Snowflake dialects
  • Execute the Snowflake side to validate the test SQL (not the object)
  • Write YAML artifacts with test_cases: [[]] for test-runner compatibility
  • Enrich YAMLs with modifies_data and affected_tables for clone isolation
  • Fix test SQL if Snowflake execution fails (up to 3 retries)

This skill does NOT:

  • Repair the migrated object — delegate failures caused by object bugs to migrate-object
  • Run uv run migrate or run_migration_tests — test execution is handled by scai test capture + scai test validate
  • Generate tests for TABLEs or VIEWs (procedures and functions only)
  • Generate tests for BTEQ scripts. Units with kind: "script" (BTEQ) author a validation.steps[].script block per ../seed-script/SKILL.md from user-provided bindings + import fixtures — they are not synthesized here. Do not invent test_cases: for them.

Read the full file on GitHub · 415 lines

Files

What ships with it

3 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.

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. 2d ago First seen · 415 lines · 88 tokens per session scan A 7d8381422b6f

Subscribe to this mod's changes

synthetic-seeder is a skill published in the GitHub repository sfc-gh-dflippo/snowflake-dbt-demo (33 stars, last pushed 3d ago), licensed Apache-2.0. It adds 88 tokens to every session and 4,632 once invoked, about $0.0004 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 2026-09-10.

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