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Agent skill

Frl Coding Standard

by FoundationDB in FoundationDB/fdb-record-layer

Coding standards for all Java code in fdb-record-layer. An agent skill from FoundationDB/fdb-record-layer.

Apache-2.0Auto-check passedDevelopment

Install Frl Coding Standard

skills CLI
$ npx skills add FoundationDB/fdb-record-layer --skill frl-coding-standard -a claude-code

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

GitHub CLI
$ gh skill install FoundationDB/fdb-record-layer frl-coding-standard --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/FoundationDB/fdb-record-layer.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/skills/frl-coding-standard .claude/skills/frl-coding-standard && 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/

Facts

Skill name
frl-coding-standard
GitHub stars
675
Token cost
~1.2k tokens
SKILL.md length
433 words
Files
1
Skills in repo
10
Repo updated
First seen
Licence
Apache-2.0

At a glance

Coding standards for all Java code in fdb-record-layer. An agent skill from FoundationDB/fdb-record-layer.

  • Tasks that involve Code quality
  • SKILL.md covers Exceptions, Logging, Futures (async code) and Checkstyle-banned imports, plus 2 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Frl Coding Standard is an agent skill from FoundationDB/fdb-record-layer. Coding standards for all Java code in fdb-record-layer. Apply when writing or reviewing any Java code. Some example usages: "Review this class for coding standards" "Write a new implementation of RecordCursor"

Its SKILL.md is about 1.2k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Development, covering Code quality. It works with Java. The repository describes itself as: A relational database with SQL support built on FoundationDB. The licence is Apache-2.0.

When your agent uses it

  • Tasks that involve Code quality

Example prompts

  • “Review this class for coding standards”
  • “Write a new implementation of RecordCursor”
  • “/frl-coding-standard”

Requirements

  • A credential in PRIMARY_KEY

What it can do on your machine

Read from SKILL.md and the folder at commit 20a2376. 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 java).

    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

Frl Coding Standard loads about 1.2k tokens when it runs. Until then it costs about 57 tokens; SKILL.md has 433 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~57
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 FoundationDB/fdb-record-layer at commit 20a2376, republished under its Apache-2.0 licence (© FoundationDB). 433 words, ~1,163 tokens.

Download SKILL.mdSave it as .claude/skills/frl-coding-standard/SKILL.md (or your agent's skills folder).
name
frl-coding-standard
description
Coding standards for all Java code in fdb-record-layer. Apply when writing or reviewing any Java code. Some example usages: "Review this class for coding standards" "Write a new implementation of RecordCursor"

All Java, Gradle, and property files MUST end with a newline character.

Target Java 17 language level, compiled with JDK 21.

Exceptions

The two layers use different exception systems. Know which layer you are in.

fdb-record-layer-* (record layer)

Exceptions extend RecordCoreException, which extends LoggableException (unchecked).

  • The exception message MUST be a static string — no string interpolation or variables.
  • Use .addLogInfo(LogMessageKeys.KEY, value) to attach context. Include as much as needed to diagnose the error: subspace, primary key, record type, index name, etc.
java
// Wrong
throw new RecordCoreException("Found corrupt record: " + record.getPrimaryKey());

// Correct
throw new RecordCoreException("Found corrupt record")
    .addLogInfo(LogMessageKeys.PRIMARY_KEY, record.getPrimaryKey())
    .addLogInfo(LogMessageKeys.RECORD_TYPE, record.getRecordType());
fdb-relational-* (relational / SQL layer)

Exceptions are RelationalException (checked, extends Exception). Always pair with an ErrorCode, which maps to a SQLSTATE-standard 5-digit code.

  • Message must still be a static string.
  • Attach context with .addContext("key", value) — this travels with the exception for logging and is preserved when converting to SQLException.
java
// Minimal form
throw new RelationalException("Transaction rolled back", ErrorCode.SERIALIZATION_FAILURE);

// With context
throw new RelationalException("Unsupported type in column", ErrorCode.CANNOT_CONVERT_TYPE)
    .addContext("columnName", colName)
    .addContext("typeName", typeName);

At JDBC interface boundaries (where the signature throws SQLException), convert via .toSqlException(), which produces a ContextualSQLException carrying the ErrorCode as the SQLState and the context map for logging:

java
throw new RelationalException("Element is not of STRUCT type", ErrorCode.CANNOT_CONVERT_TYPE)
    .toSqlException();

Specialized subclasses (InvalidColumnReferenceException, InvalidTypeException) exist for common error cases — prefer them when they fit. InternalErrorException is deprecated; use new RelationalException("...", ErrorCode.INTERNAL_ERROR) directly.

UncheckedRelationalException wraps a RelationalException as a RuntimeException for contexts where checked exceptions cannot be thrown (e.g., inside lambdas). Unwrap with .unwrap() to recover the original RelationalException.

Logging

Same principle as exceptions — structured, static messages:

  • Always use KeyValueLogMessage.of("static message", key, value, ...).
  • The message text must be a static string. Variables go in key/value pairs.
java
// Wrong
LOGGER.info("Unable to open file: " + filename);

// Correct
LOGGER.info(KeyValueLogMessage.of("Unable to open file", LogMessageKeys.FILENAME, filename));
Show full SKILL.md (201 more words)Show less

Futures (async code)

The fdb-record-layer-* and lower-level parts of fdb-relational-core are fully asynchronous via CompletableFuture. The JDBC-facing relational API presents a synchronous surface, but async code is common in the implementation beneath it.

  • Never call join() or get() in production code. Use context.asyncToSync() or database.asyncToSync() instead — they enforce timeouts, record wait timers, and handle error wrapping.
  • Never call any blocking method from inside a CompletableFuture completion lambda. The thread pool is finite; blocking inside a future can deadlock the entire system.
  • Avoid thenApplyAsync() / thenComposeAsync() unless the lambda does significant CPU work. These enqueue a new task on the executor for no benefit in the common case. When you do need them, always pass an explicit Executor.
  • Always pass an Executor to any AsyncUtil or MoreAsyncUtil method that accepts one (e.g. AsyncUtil.whileTrue()). Never use the overload without an executor.

Checkstyle-banned imports

The authoritative list is in gradle/check.gradle (BANNED_IMPORTS).

Inline comments

Describe intent, not mechanics. Explain the why — a hidden constraint, a non-obvious invariant, a workaround for a specific FDB behavior. If removing the comment would not confuse a future reader, don't write it.

Javadoc

Add Javadoc for public APIs. It is not necessary for private methods unless the logic is genuinely non-obvious.

© FoundationDB, Apache-2.0. 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 .claude/skills/frl-coding-standard of FoundationDB/fdb-record-layer.

Open the folder on GitHubat commit 20a2376

Compare with similar skills

Frl Coding Standard 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.

Frl Coding Standard compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Frl Coding Standard this skillFoundationDB/fdb-record-layer675—~1.2kAutomated safety check: PassApache-2.0
Code Review Skillawesome-skills/code-review-skill2.1k—~2.8kAutomated safety check: NotesMIT
New Rule for sonar-javaSonarSource/sonar-java1.2k—~833Automated safety check: PassCustom licence
Cross-Language Coding Standardszereight/gitlab-mcp2k1 repos~1.4kAutomated safety check: PassMIT
Code Qualitypiomin/claude-ai-spring-boot1.3k—~2.2kAutomated safety check: PassApache-2.0
Android Code Quality Checkerwordpress-mobile/WordPress-Android3.2k—~587Automated safety check: PassGPL-2.0

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More from FoundationDB/fdb-record-layer

All 10 skills in this repo

  • Relational Query Processor

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    Specialized skill for working in the fdb-relational-core SQL processing layer — parser, plan generator, and Cascades planner.

    675 GitHub stars~1k tokensUpdated today
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  • Using Gradle

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  • Context Resumption

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  • Docs Writer

    FoundationDB/fdb-record-layer

    Write or update documentation in docs/sphinx/source/. An agent skill from FoundationDB/fdb-record-layer.

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  • Frl Test Coding Standard

    FoundationDB/fdb-record-layer

    Standards for writing tests in fdb-record-layer. An agent skill from FoundationDB/fdb-record-layer.

    675 GitHub stars~792 tokensUpdated today
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  • Stacked PRs

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    Create and manage stacked pull requests on FoundationDB/fdb-record-layer using the gh stack CLI extension.

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Works with

Categories

Questions about Frl Coding Standard

What does Frl Coding Standard do?

Coding standards for all Java code in fdb-record-layer. An agent skill from FoundationDB/fdb-record-layer. Frl Coding Standard is an agent skill from FoundationDB/fdb-record-layer. Coding standards for all Java code in fdb-record-layer.

When should I use Frl Coding Standard?

Frl Coding Standard fits situations like: tasks that involve Code quality.

How do I install Frl Coding Standard in Claude Code?

Run `npx skills add FoundationDB/fdb-record-layer --skill frl-coding-standard -a claude-code`. Or copy the skill folder (.claude/skills/frl-coding-standard in FoundationDB/fdb-record-layer) into .claude/skills/frl-coding-standard in your project. Claude Code loads it when a task matches its description.

How do I install Frl Coding Standard in Codex?

Run `npx skills add FoundationDB/fdb-record-layer --skill frl-coding-standard -a codex`. Or copy the skill folder (.claude/skills/frl-coding-standard in FoundationDB/fdb-record-layer) into .agents/skills/frl-coding-standard in your project. Codex loads it when a task matches its description.

Can I use Frl Coding Standard 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 FoundationDB/fdb-record-layer --skill frl-coding-standard -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/frl-coding-standard, .gemini/skills/frl-coding-standard, .github/skills/frl-coding-standard and .opencode/skills/frl-coding-standard in your project.

What does Frl Coding Standard need to run?

SKILL.md names no scripts, command-line tools or credentials: Frl Coding Standard is instructions for the agent only. Our summary lists: A credential in PRIMARY_KEY.

Does Frl Coding Standard 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 Frl Coding Standard 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 Frl Coding Standard use?

Frl Coding Standard 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 Frl Coding Standard 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 Frl Coding Standard?

Skills that share tags, products or a category with Frl Coding Standard: Code Review Skill (awesome-skills/code-review-skill, 2.1k stars), New Rule for sonar-java (SonarSource/sonar-java, 1.2k stars), Cross-Language Coding Standards (zereight/gitlab-mcp, 2k stars) and Code Quality (piomin/claude-ai-spring-boot, 1.3k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Frl Coding Standard?

FoundationDB (a GitHub organization) maintains it in FoundationDB/fdb-record-layer, which has 675 GitHub stars. The repository holds 10 skills in this directory. The repository was last updated on October 6, 2026.

Source: FoundationDB/fdb-record-layer on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.