# Terraform 1 13

> Apply Terraform 1.13 language, CLI, state, testing, migration, and behaviour changes. Load for Terraform work targeting 1.13 or later when the model's knowledge may predate the 2025-08-20 release.

- Skill: `cedws/terraform-1-13` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add cedws/terraform-1-13`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cedws/terraform-1-13/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: DevOps & Infra
- Author: cedws (https://skillmd.com/u/cedws)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/cedws/terraform-1-13

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# Terraform 1.13

This overview applies when the project's target Terraform version is at least 1.13.

## Stacks and automation

- The `terraform stacks` command exposes stack operations through a separately installed Stacks plugin. Available subcommands depend on that plugin and are discoverable with `terraform stacks -help`.
- `terraform rpcapi` is generally available for internal integrations using the go-plugin-compatible RPC interface; it is not a stable public automation surface.

## Testing

- Test files can declare definitions for external variables they reference, improving type checking and diagnostics for complex inputs.
- File-level variable values can refer to run outputs and other variables.
- Test teardown operations can execute in parallel where their dependencies permit it.

## Validation and state

- Filesystem functions are checked for consistent results between evaluation phases, exposing configuration that would otherwise produce an inconsistent final plan.
- Static validation detects more invalid indexed references before provider operations.
- Nested module outputs preserve their sensitivity marks through state and evaluation.