x-format-code

Global Output Policy

• Language: English ONLY.
• Tone: Technical, Direct, and Concise.
• Efficiency: Remove all conversational fillers and greetings to save tokens.

Skill: Format Code (slim — ADR-0012)

Ensures source code in {{PROJECT_NAME}} follows a consistent style before commits. First step of the pre-commit chain (RULE-007: x-format-code -> x-lint-code -> compile -> commit). Detects {{LANGUAGE}}, selects the appropriate formatter, runs it, and re-stages modified files automatically.

Triggers

• /x-format-code -- format all project files
• /x-format-code --check -- verify formatting without modifying files (CI mode)
• /x-format-code --changed-only -- format only modified files (staged + unstaged)

Parameters

Parameter	Required	Description
--check	No	Dry-run: exit 0 if formatted, exit 1 if not. No files modified.
--changed-only	No	Format only files detected via git diff (staged + unstaged).

Output Contract

• Mutation: files formatted in place (unless --check). Previously-staged files are automatically re-staged after format.
• Exit codes: 0 success / nothing to do; 1 formatter not installed, execution failure, or violations under --check.
• Report to stdout: language, formatter used, files checked, files reformatted, files re-staged.
• Supported languages / formatter commands: see references/full-protocol.md §1 for the full mapping. Slim summary: spotless (java), prettier (typescript), ruff/black (python), gofmt (go), rustfmt (rust), ktfmt (kotlin).

Error Envelope

Chain-wide error matrix. Canonical format -> lint -> compile -> commit rows live in _shared/error-handling-pre-commit.md. Rows below are x-format-code-specific.

Scenario	Behavior	Exit
Unsupported language ({{LANGUAGE}} not in table)	Report warning, do NOT block chain	0
No formatter installed (primary + fallback missing)	Report error with install instructions	1
Formatter execution fails	Report error with stderr output	1
No files to format	Report "No files to format"	0
--check finds violations	List files needing formatting	1
Re-stage failure (git add error)	Report error with git stderr	1

Full Protocol

Minimum viable contract above. Detailed language/formatter mapping, the 6-step workflow (detect → select → scope → execute → re-stage → report), build-tool configuration examples (Maven/Gradle/npm/Python/Go/Rust), and per-language file extension lists live in references/full-protocol.md per ADR-0012 (skill body slim-by-default). Happy-path invocation needs only this SKILL.md; full protocol is consulted when a new language or fallback formatter is introduced.

Integration Notes

Skill	Relationship	Context
x-lint-code	follows	Second step of the pre-commit chain (after format).
x-commit-changes	orchestrator	Invokes this skill as step 3a of its chain.

Template Variables

Variable	Description	Example
{{LANGUAGE}}	Project language	java
{{BUILD_TOOL}}	Project build tool	maven
{{PROJECT_NAME}}	Project name	my-java-cli