Agent skill

Ecto Persistence Patterns

by georgeguimaraes in georgeguimaraes/elixir-agent-tools

Designs and debugs Elixir persistence with Ecto: schemas, changesets, queries, preloads, migrations and multi-tenancy, kept within application contexts.

Apache-2.0Auto-check passedBackend & APIs

Install Ecto Persistence Patterns

skills CLI

$ npx skills add georgeguimaraes/elixir-agent-tools --skill ecto -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install georgeguimaraes/elixir-agent-tools ecto --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/georgeguimaraes/elixir-agent-tools.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/elixir-dev/skills/ecto .claude/skills/ecto && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "ecto" agent skill from https://github.com/georgeguimaraes/elixir-agent-tools/tree/main/plugins/elixir-dev/skills/ecto into .claude/skills/ecto/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ecto", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/georgeguimaraes/elixir-agent-tools/tree/main/plugins/elixir-dev/skills/ecto

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add georgeguimaraes/elixir-agent-tools --skill ecto -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install georgeguimaraes/elixir-agent-tools ecto --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/georgeguimaraes/elixir-agent-tools.git skills-src && mkdir -p .agents/skills && cp -r skills-src/plugins/elixir-dev/skills/ecto .agents/skills/ecto && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "ecto" agent skill from https://github.com/georgeguimaraes/elixir-agent-tools/tree/main/plugins/elixir-dev/skills/ecto into .agents/skills/ecto/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ecto", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add georgeguimaraes/elixir-agent-tools --skill ecto -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install georgeguimaraes/elixir-agent-tools ecto --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/georgeguimaraes/elixir-agent-tools.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/plugins/elixir-dev/skills/ecto .cursor/skills/ecto && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "ecto" agent skill from https://github.com/georgeguimaraes/elixir-agent-tools/tree/main/plugins/elixir-dev/skills/ecto into .cursor/skills/ecto/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ecto", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/georgeguimaraes/elixir-agent-tools.git --path plugins/elixir-dev/skills/ecto

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add georgeguimaraes/elixir-agent-tools --skill ecto -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install georgeguimaraes/elixir-agent-tools ecto --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/georgeguimaraes/elixir-agent-tools.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/plugins/elixir-dev/skills/ecto .gemini/skills/ecto && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "ecto" agent skill from https://github.com/georgeguimaraes/elixir-agent-tools/tree/main/plugins/elixir-dev/skills/ecto into .gemini/skills/ecto/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ecto", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install georgeguimaraes/elixir-agent-tools ecto

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add georgeguimaraes/elixir-agent-tools --skill ecto -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/georgeguimaraes/elixir-agent-tools.git skills-src && mkdir -p .github/skills && cp -r skills-src/plugins/elixir-dev/skills/ecto .github/skills/ecto && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "ecto" agent skill from https://github.com/georgeguimaraes/elixir-agent-tools/tree/main/plugins/elixir-dev/skills/ecto into .github/skills/ecto/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ecto", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add georgeguimaraes/elixir-agent-tools --skill ecto -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install georgeguimaraes/elixir-agent-tools ecto --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/georgeguimaraes/elixir-agent-tools.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/plugins/elixir-dev/skills/ecto .opencode/skills/ecto && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "ecto" agent skill from https://github.com/georgeguimaraes/elixir-agent-tools/tree/main/plugins/elixir-dev/skills/ecto into .opencode/skills/ecto/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "ecto", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: ecto
GitHub stars: 184
Token cost: ~1.2k tokens
SKILL.md length: 444 words
Files: 1
Skills in repo: 5
Repo updated: Sep 20, 2026
First seen: Oct 7, 2026
Licence: Apache-2.0

At a glance

Designs and debugs Elixir persistence with Ecto: schemas, changesets, queries, preloads, migrations and multi-tenancy, kept within application contexts.

Designing Ecto schemas and changesets for a new feature
SKILL.md covers Context = Setting That Changes…, Cross-Context References: IDs,…, DDD Patterns as Pipelines and Schema ≠ Database Table, plus 7 more sections
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md
Choosing between preloads and joins when loading associations

What it does

The skill starts from the idea that a context changes what words mean, so each bounded context may have its own Product schema and table. Design goes top-down from subdomain to context to entity, cross-context references use IDs rather than associations, and queries go through the context. Domain patterns are written as pipelines, with events passed as data structs. It also keeps schema and table apart: embedded schemas serve forms and API payloads, and one schema can have several changesets such as registration, profile and admin.

For multi-tenancy it recommends composite foreign keys and prepare_query/3 for automatic scoping, raising when org_id is missing. For preloads, separate queries suit large has-many sets and join preloads suit belongs-to and has-one, since joins can use ten times the memory on has-many. Plain CRUD contexts are fine, and generators cover simple cases. It lists gotchas from the Ecto core team, including CTEs not inheriting the schema prefix in multi-tenant apps and parameterized queries not being prepared statements.

When your agent uses it

Designing Ecto schemas and changesets for a new feature
Choosing between preloads and joins when loading associations
Adding tenant scoping to queries in a multi-tenant Elixir app
Deciding how contexts should reference each other

Example prompts

“Design Ecto schemas and changesets for a signup flow with separate registration and profile updates.”
“This query preloads thousands of comments per post and uses too much memory; fix it.”
“Add tenant scoping by org_id to every query in the Billing context.”
“Review my migration for composite foreign keys across tenants.”

What it can do on your machine

Read from SKILL.md and the folder at commit ac3a5a1. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are elixir).
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
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

Ecto Persistence Patterns loads about 1.2k tokens when it runs. Until then it costs about 61 tokens; SKILL.md has 444 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~61
When it runs · the whole SKILL.md, loaded when a task matches: ~1.2k

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

Auto-check passed

The automated check found no risky patterns in SKILL.md.

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 georgeguimaraes/elixir-agent-tools at commit ac3a5a1, republished under its Apache-2.0 licence (© georgeguimaraes). 444 words, ~1,163 tokens.

Download SKILL.mdSave it as .claude/skills/ecto/SKILL.md (or your agent's skills folder).

name: ecto
description: Design and debug Elixir persistence with Ecto. Use for schemas, changesets, queries, preloads, transactions, migrations, multi-tenancy, and data access through application contexts. Covers database query performance and connection pools.

Ecto

Model persistence, compose queries, and keep data access within application boundaries.

Context = Setting That Changes Meaning

Context isn't just a namespace—it changes what words mean. "Product" means different things in Checkout (SKU, name), Billing (SKU, cost), and Fulfillment (SKU, warehouse). Each bounded context may have its OWN Product schema/table.

Think top-down: Subdomain → Context → Entity. Not "What context does Product belong to?" but "What is a Product in this business domain?"

Cross-Context References: IDs, Not Associations

elixir

schema "cart_items" do
  field :product_id, :integer  # Reference by ID
  # NOT: belongs_to :product, Catalog.Product
end

Query through the context, not across associations. Keeps contexts independent and testable.

DDD Patterns as Pipelines

elixir

def create_product(params) do
  params
  |> Products.build()       # Factory: unstructured → domain
  |> Products.validate()    # Aggregate: enforce invariants
  |> Products.insert()      # Repository: persist
end

Use events (as data structs) to compose bounded contexts with minimal coupling.

Schema ≠ Database Table

Use Case	Approach
Database table	Standard `schema/2`
Form validation only	`embedded_schema/1`
API request/response	Embedded schema or schemaless

Multiple Changesets per Schema

elixir

def registration_changeset(user, attrs)  # Full validation + password
def profile_changeset(user, attrs)       # Name, bio only
def admin_changeset(user, attrs)         # Role, verified_at

Different operations = different changesets.

Multi-Tenancy: Composite Foreign Keys

elixir

add :post_id, references(:posts, with: [org_id: :org_id], match: :full)

Use prepare_query/3 for automatic scoping. Raise if org_id missing.

Preload vs Join Trade-offs

Approach	Best For
Separate preloads	Has-many with many records (less memory)
Join preloads	Belongs-to, has-one (single query)

Join preloads can use 10x more memory for has-many.

CRUD Contexts Are Fine

"If you have a CRUD bounded context, go for it. No need to add complexity."

Use generators for simple cases. Add DDD patterns only when business logic demands it.

Gotchas from Core Team

CTE Queries Don't Inherit Schema Prefix

In multi-tenant apps, CTEs don't get the parent query's prefix.

Fix: Explicitly set prefix: %{recursive_query | prefix: "tenant"}

Parameterized Queries ≠ Prepared Statements

Parameterized queries: WHERE id = $1 — always used by Ecto
Prepared statements: Query plan cached by name — can be disabled

pgbouncer: Use prepare: :unnamed (disables prepared statements, keeps parameterized queries).

Show full SKILL.md (176 more words)Show less

pool_count vs pool_size

More pools with fewer connections = better for benchmarks. But with mixed fast/slow queries, a single larger pool gives better latency.

Rule: pool_count for uniform workloads, larger pool_size for real apps.

Sandbox Mode Doesn't Work With External Processes

Cachex, separate GenServers, or anything outside the test process won't share the sandbox transaction.

Fix: Make the external service use the test process, or accept it's not in the same transaction.

Null Bytes Crash Postgres

PostgreSQL rejects null bytes even though they're valid UTF-8.

Fix: Sanitize at boundaries: String.replace(string, "\x00", "")

preload_order for Association Sorting

elixir

has_many :comments, Comment, preload_order: [desc: :inserted_at]

Note: Doesn't work for through associations.

Runtime Migrations Use List API

elixir

Ecto.Migrator.run(Repo, [{0, Migration1}, {1, Migration2}], :up, opts)

Idioms

Prefer Repo.insert/1 over Repo.insert!/1—handle {:ok, _} / {:error, _} explicitly
Use Repo.transact/1 (Ecto 3.12+) for simple transactions instead of Ecto.Multi

Red Flags - STOP and Reconsider

belongs_to pointing to another context's schema
Single changeset for all operations
Preloading has-many with join
CTEs in multi-tenant apps without explicit prefix
Using pgbouncer without prepare: :unnamed
Testing with Cachex/GenServers assuming sandbox shares transactions
Accepting user input without null byte sanitization

Any of these? Re-read the Gotchas section.

Files

Just SKILL.md in plugins/elixir-dev/skills/ecto of georgeguimaraes/elixir-agent-tools.

Open the folder on GitHubat commit ac3a5a1

Compare with similar skills

Ecto Persistence Patterns next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Ecto Persistence Patterns compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Ecto Persistence Patterns this skillgeorgeguimaraes/elixir-agent-tools	184	—	~1.2k	Automated safety check: Pass	Apache-2.0	19 days ago
Dsqlawslabs/agent-plugins	915	—	~6.9k	Automated safety check: Pass	Apache-2.0	yesterday
DB SculptorEliasOulkadi/shokunin	114	—	~3.1k	Automated safety check: Notes	MIT	4 days ago
Jpa Patternsaffaan-m/ECC	276k	5 repos	~1.2k	Automated safety check: Pass	MIT	4 days ago
Prisma Expertdavila7/claude-code-templates	32k	7 repos	~2.6k	Automated safety check: Pass	MIT	today
Discover Databaserand/cc-polymath	181	—	~2k	Automated safety check: Pass	MIT	7 mo ago

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Questions about Ecto Persistence Patterns

What does Ecto Persistence Patterns do?

Designs and debugs Elixir persistence with Ecto: schemas, changesets, queries, preloads, migrations and multi-tenancy, kept within application contexts. The skill starts from the idea that a context changes what words mean, so each bounded context may have its own Product schema and table. Design goes top-down from subdomain to context to entity, cross-context references use IDs rather than associations, and queries go through the context.

When should I use Ecto Persistence Patterns?

Ecto Persistence Patterns fits situations like: designing Ecto schemas and changesets for a new feature; choosing between preloads and joins when loading associations; adding tenant scoping to queries in a multi-tenant Elixir app; deciding how contexts should reference each other.

How do I install Ecto Persistence Patterns in Claude Code?

Run `npx skills add georgeguimaraes/elixir-agent-tools --skill ecto -a claude-code`. Or copy the skill folder (plugins/elixir-dev/skills/ecto in georgeguimaraes/elixir-agent-tools) into .claude/skills/ecto in your project. Claude Code loads it when a task matches its description.

How do I install Ecto Persistence Patterns in Codex?

Run `npx skills add georgeguimaraes/elixir-agent-tools --skill ecto -a codex`. Or copy the skill folder (plugins/elixir-dev/skills/ecto in georgeguimaraes/elixir-agent-tools) into .agents/skills/ecto in your project. Codex loads it when a task matches its description.

Can I use Ecto Persistence Patterns in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add georgeguimaraes/elixir-agent-tools --skill ecto -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/ecto, .gemini/skills/ecto, .github/skills/ecto and .opencode/skills/ecto in your project.

What does Ecto Persistence Patterns need to run?

SKILL.md names no scripts, command-line tools or credentials: Ecto Persistence Patterns is instructions for the agent only.

Does Ecto Persistence Patterns access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Ecto Persistence Patterns safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Ecto Persistence Patterns use?

Ecto Persistence Patterns is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Ecto Persistence Patterns use?

About 1.2k tokens (SKILL.md is roughly 4.7k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Ecto Persistence Patterns?

Skills that share tags, products or a category with Ecto Persistence Patterns: Dsql (awslabs/agent-plugins, 915 stars), DB Sculptor (EliasOulkadi/shokunin, 114 stars), Jpa Patterns (affaan-m/ECC, 276k stars) and Prisma Expert (davila7/claude-code-templates, 32k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Ecto Persistence Patterns?

georgeguimaraes (a GitHub user) maintains it in georgeguimaraes/elixir-agent-tools, which has 184 GitHub stars. The repository holds 5 skills in this directory. The repository was last updated on September 20, 2026.

Source: georgeguimaraes/elixir-agent-tools on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Ecto Persistence Patterns

Facts

At a glance

What it does

When your agent uses it

Example prompts

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Ecto

Context = Setting That Changes Meaning

Cross-Context References: IDs, Not Associations

DDD Patterns as Pipelines

Schema ≠ Database Table

Multiple Changesets per Schema

Multi-Tenancy: Composite Foreign Keys

Preload vs Join Trade-offs

CRUD Contexts Are Fine

Gotchas from Core Team

CTE Queries Don't Inherit Schema Prefix

Parameterized Queries ≠ Prepared Statements

pool_count vs pool_size

Sandbox Mode Doesn't Work With External Processes

Null Bytes Crash Postgres

preload_order for Association Sorting

Runtime Migrations Use List API

Idioms

Red Flags - STOP and Reconsider

Files

Compare with similar skills

Similar skills

More from georgeguimaraes/elixir-agent-tools

Related

Questions about Ecto Persistence Patterns