Add local fix script and codex validation guidance

AGENTS.md

@@ -59,6 +59,19 @@ Changes should keep the provider idiomatic, easy to contribute to, and ready for
 
 ## Agent instructions
 
+## Validation workflow (Codex and local)
+
+When you modify **Go** or **Terraform** files, always run this sequence before concluding work:
+
+1. `./scripts/fix.sh`
+2. `./scripts/check.sh`
+
+### Expectations
+- Do not leave formatting changes unapplied.
+- Do not hand-edit formatting that `gofmt` or `terraform fmt` can apply automatically.
+- Treat `./scripts/check.sh` as the required final validation gate.
+- If Terraform is unavailable in the environment, note that Terraform formatting/checking could not be run locally.
+
 ### Local validation for this repository
 
 This provider is not yet published to the Terraform Registry.

README.md

@@ -181,6 +181,18 @@ data "dynu_dns_records" "selected" {
   - Symptom: Terraform behavior doesn't reflect latest code.
   - Fix: rebuild binary (`go build -o terraform-provider-dynu`) and re-run `terraform validate` and `terraform plan`.
 
+## Development checks
+
+Before committing, run:
+
+```bash
+./scripts/fix.sh
+./scripts/check.sh
+```
+
+`fix.sh` applies standard formatting and module hygiene.  
+`check.sh` is the strict verification script used by CI.
+
 ## Developer workflow
 
 - `./scripts/setup-dev.sh` - validate local toolchain requirements

scripts/fix.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+echo "[fix] formatting Go files"
+files="$(git ls-files '*.go')"
+if [[ -n "${files}" ]]; then
+  gofmt -w ${files}
+fi
+
+echo "[fix] running go mod tidy"
+go mod tidy
+
+if command -v terraform >/dev/null 2>&1; then
+  echo "[fix] running terraform fmt for examples/"
+  terraform fmt -recursive examples
+else
+  echo "[fix][warn] terraform not found; skipping examples/ formatting" >&2
+fi
+
+echo "[fix] complete"