Dj Prefixed Ulids

What it does

When your agent uses it

• Setting up a new model
• Reviewing a schema that still uses auto-increment
• UUID primary keys
• The user mentions IDs

Example prompts

• “/dj-prefixed-ulids”

Requirements

• Python 3
• Pre-approved tools (allowed-tools): Read, Write, Edit, Bash, Grep, Glob

Workflow steps

4 steps, taken from the first numbered list in SKILL.md.

1. 1Add a new CharField column with the prefixed ULID default, nullable at first.
2. 2Backfill with a data migration that assigns prefixed_ulid("prd") to every existing row.
3. 3Add unique=True and make it non-nullable in a follow-up migration.
4. 4Swap it to primary_key=True only after every foreign key has been migrated to reference the new column — this usually means a…

What it can do on your machine

Read from SKILL.md and the folder at commit f17fc2d. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Read
  • Write
  • Edit
  • Bash
  • Grep
  • Glob

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  Shell commands in SKILL.md call:

  • uv

  From the folder's file list and the shell code blocks in SKILL.md.

• Network

  Links to these hosts (documentation or services it may open):

  • github.com

  From URLs in SKILL.md, links to its own repository left out.

• Credentials

  Names no API keys, tokens, secrets or passwords.

  From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Dj Prefixed Ulids loads about 1.4k tokens when it runs. Until then it costs about 108 tokens; SKILL.md has 547 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~108

When it runs · the whole SKILL.md, loaded when a task matches

~1.4k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

• NotePre-approves every shell command (allowed-tools: Bash)SKILL.md

  allowed-tools: Read, Write, Edit, Bash, Grep, Glob

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from dvf/opinionated-django at commit f17fc2d, republished under its MIT licence (© dvf). 547 words, ~1,353 tokens.

name

dj-prefixed-ulids

description

Use Stripe-style prefixed ULID primary keys (e.g. `prd_01jq3v...`) for every Django model instead of integers or UUIDs. Use when setting up a new model, reviewing a schema that still uses auto-increment or UUID primary keys, or when the user mentions IDs, slugs, public identifiers, or referential debugging. Produces short readable prefixes, time-sortable values, and IDs that are safe to expose in URLs and logs.

allowed-tools

Read, Write, Edit, Bash, Grep, Glob

prd_01jq3v8f6a7b2c8d9e0f1g2h3j4k
ord_01jq3v8fgh7x2y5z9a1b2c3d4e5f

from ulid import ULID


def prefixed_ulid(prefix: str) -> str:
    return f"{prefix}_{str(ULID()).lower()}"


def _make_generator(prefix: str):
    def generate() -> str:
        return prefixed_ulid(prefix)

    generate.__name__ = f"generate_{prefix}_id"
    generate.__qualname__ = f"generate_{prefix}_id"
    return generate

generate_prd_id = _make_generator("prd")
generate_ord_id = _make_generator("ord")
generate_itm_id = _make_generator("itm")

from typing import ClassVar

from django.db import models

from project.ids import generate_prd_id


class Product(models.Model):
    __prefix__: ClassVar[str] = "prd"
    id = models.CharField(
        max_length=64,
        primary_key=True,
        default=generate_prd_id,
        editable=False,
    )
    name = models.CharField(max_length=255)

    def __str__(self) -> str:
        return self.name

uv run ruff check src
uv run pyrefly check src
uv run pytest

© dvf, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/dj-prefixed-ulids of dvf/opinionated-django.

Open the folder on GitHubat commit f17fc2d