What is alembic-migration?

A tool for creating Alembic migrations, which are tracked changes to a database's structure.

Use it when adding tables or columns, changing database fields, or checking migration tests.

It helps keep schema changes linked to the current database version, repeatable, and free of multiple migration branches.

alembic-migration — Skill for Claude Code by jrmatherly

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.

Any agent

npx skills add jrmatherly/mcp-context-forge --skill alembic-migration

Clone the repo

git clone --depth 1 https://github.com/jrmatherly/mcp-context-forge

Made for: Claude Code.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/jrmatherly/mcp-context-forge/alembic-migration/github.svg)](https://agentmods.dev/skills/jrmatherly/mcp-context-forge/alembic-migration)

Your own site

<a href="https://agentmods.dev/skills/jrmatherly/mcp-context-forge/alembic-migration"><img src="https://agentmods.dev/badge/skills/jrmatherly/mcp-context-forge/alembic-migration/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/jrmatherly/mcp-context-forge/alembic-migration"><img src="https://agentmods.dev/badge/skills/jrmatherly/mcp-context-forge/alembic-migration.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 372 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.

Model	Per session	Once invoked
Fable 5.1	$0.00037	$0.00372
Opus 5	$0.00018	$0.00186
Sonnet 5	$0.00007	$0.00074
Haiku 4.5	$0.00004	$0.00037

Measured 6d ago against content hash 6e743f83da3e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

alembic-migration 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 6d 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/skills/alembic-migration/SKILL.md · 50 lines

What it actually says

Create an Alembic migration for: $ARGUMENTS

Critical Rules (from CLAUDE.md)

down_revision MUST point to the actual current head (verified below)
Never guess or copy down_revision from older migrations
Multiple heads = broken tests. Always verify single head after creating.
Write idempotent migrations that check before modifying.

Steps

Verify current head (this is the value for down_revision):
```
cd mcpgateway && alembic heads
```

Generate the migration:

cd mcpgateway && alembic revision --autogenerate -m "$ARGUMENTS"

Edit the generated file to make it idempotent:

def upgrade() -> None:
    inspector = sa.inspect(op.get_bind())
    if "my_table" not in inspector.get_table_names():
        return
    columns = [col["name"] for col in inspector.get_columns("my_table")]
    if "new_column" in columns:
        return
    op.add_column("my_table", sa.Column("new_column", sa.String(), nullable=True))

Verify single head after creation:
```
cd mcpgateway && alembic heads
```
Must show exactly ONE head. If multiple, fix down_revision.
Run tests to confirm:
```
make test
```

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.

6d ago First seen · 50 lines · 37 tokens per session scan A 6e743f83da3e

Subscribe to this mod's changes

alembic-migration is a skill published in the GitHub repository jrmatherly/mcp-context-forge (0 stars, last pushed 6mo ago), licensed Apache-2.0. It adds 37 tokens to every session and 372 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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