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no-fstring-sql-interpolation

Do not build SQL by interpolating values with f-strings, .format(), or +.

Skill by StopThatSlop

IndexedMIT★ 4
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Works with Claude Code, Claude apps, Codex, Cursor, Gemini CLI, GitHub Copilot, VS Code, OpenCode, Goose, Windsurf. Read the repository before you give any tool access to your data.

npx agentmarket install skill/stopthatslop-no-fstring-sql-interpolation

Asks which of your tools to add it to (Claude Code, Codex, Cursor, VS Code, Windsurf, Gemini CLI, Claude Desktop) and shows the change first. See https://agentmart.dev/cli.

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About

Do not build SQL by interpolating values with f-strings, .format(), or +. Use bound parameters. Use only when editing Python code that composes SQL or Cypher queries. Do not use for ORM query builders, identifiers assembled from a trusted allowlist, or non-SQL string templates.

Use cases: backend, writing

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Permissions

What this skill can do and what it asks for, from its SKILL.md. Checked Oct 25, 2026.

Tools
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Install scripts
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Network hosts it talks to 1

  • codeload.github.com · found in install command

Files it touches

  • ~/.claude/skills/no-fstring-sql-interpolation

What's inside

Skill name
no-fstring-sql-interpolation
Description
Do not build SQL by interpolating values with f-strings, .format(), or +. Use bound parameters. Use only when editing Python code that composes SQL or Cypher queries. Do not use for ORM query builders, identifiers assembled from a trusted allowlist, or non-SQL string templates.
License
MIT
Metadata
pack: stopthatslop-python-fastapi-v1 · globs: **/*.py · engine_rule_id: python.sql.no-fstring-sql-interpolation
Instructions
36 lines in SKILL.md · view on GitHub

Files (1)

  • SKILL.md

SKILL.md (first lines)

# No f-string SQL interpolation

Interpolated values are an injection surface and a plan-cache killer. Agents
write `f"... WHERE email = '{email}'"` because it reads nicely. Bound
parameters read nearly as well and are safe.

## Do

```python
def find_user(conn, email: str) -> dict | None:
    row = conn.execute(
        "SELECT id, email FROM users WHERE email = %s",
        (email,),
    ).fetchone()
    return dict(row) if row else None
```

## Do not

```python
def find_user(conn, email: str) -> dict | None:
    row = conn.execute(
        f"SELECT id, email FROM users WHERE email = '{email}'"
    ).fetchone()
    return dict(row) if row else None
```

The same rule covers `.format()`, `%` formatting, and string concatenation of
user-controlled values into any query text.

## Enforce

This skill is teach-only. No engine detector exists yet; CI must not fail on
it.

From StopThatSlop/stopthatslop, MIT.

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Signals

Stars
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Last commit (this folder)
Sep 1, 2026 (1 month ago)
Last release
Sep 13, 2026 (1 month ago)

From GitHub (fetched Oct 24, 2026).

Details

License
MIT
Repository
github.com/StopThatSlop/stopthatslop
Website
stopthatslop.com
First seen
Oct 24, 2026
Last checked
Oct 24, 2026
Source
GitHubgithub-graphql

More from StopThatSlop

Cite this page

no-fstring-sql-interpolation skill. Agent Mart. https://agentmart.dev/skills/stopthatslop-no-fstring-sql-interpolation (last updated 2026-10-24)