chore: add rust-precommit skill and cross-platform script

Author: karthiknadig

.github/skills/rust-precommit/SKILL.md

@@ -0,0 +1,47 @@
+---
+name: "rust-precommit"
+description: "Run the mandatory PET Rust pre-commit checks (cargo fmt + cargo clippy -D warnings) before every commit. Invoke whenever you are about to commit Rust changes, after applying review feedback, or whenever you need to verify formatting and lint cleanliness."
+---
+
+# Rust Pre-Commit Checks
+
+The PET maintainer workflow requires `cargo fmt --all` and `cargo clippy --all -- -D warnings` to pass before every commit. This skill wraps both into a single script invocation.
+
+## When to use
+
+- Before staging any Rust changes for commit.
+- After fixing review comments on a PR, before pushing.
+- Whenever the agent is asked "run pre-commit checks" or "validate the Rust code".
+
+## How to run
+
+From the workspace root:
+
+### Windows (pwsh)
+
+```powershell
+./scripts/rust-precommit.ps1
+```
+
+### macOS / Linux
+
+```bash
+./scripts/rust-precommit.sh
+```
+
+Both scripts:
+
+1. Run `cargo fmt --all` (auto-formats; fails only on unrecoverable errors).
+2. Run `cargo clippy --all -- -D warnings` (treats warnings as errors).
+3. Exit non-zero on the first failure so callers can gate commits.
+
+## Handling failures
+
+- **fmt failure:** rare; usually a syntax error preventing parsing. Fix the underlying compile error first.
+- **clippy failure:** read the diagnostic, fix the code. Do **not** add `#[allow(...)]` to suppress unless absolutely justified.
+- After any fix, re-run the script until it reports `ALL PRE-COMMIT CHECKS PASSED`.
+
+## Notes
+
+- The script must be run from the repository root (or pass the workspace path as the first arg to the `.sh` variant / `-WorkspacePath` to the `.ps1` variant).
+- Keep the script in sync with `.github/copilot-instructions.md` "Required Before Committing" section.

scripts/rust-precommit.ps1

@@ -0,0 +1,41 @@
+#!/usr/bin/env pwsh
+# Rust pre-commit checks for PET workspace.
+# Runs `cargo fmt --all` and `cargo clippy --all -- -D warnings`.
+# Exits non-zero on any failure so callers can gate commits.
+
+[CmdletBinding()]
+param(
+    [string]$WorkspacePath = (Get-Location).Path
+)
+
+$ErrorActionPreference = 'Stop'
+Set-Location -Path $WorkspacePath
+
+Write-Host '=== RUST PRE-COMMIT CHECKS ===' -ForegroundColor Cyan
+
+if (-not (Get-Command cargo -ErrorAction SilentlyContinue)) {
+    Write-Error 'FAIL: cargo not found in PATH'
+    exit 1
+}
+
+Write-Host ''
+Write-Host '--- Step 1: cargo fmt --all ---' -ForegroundColor Cyan
+& cargo fmt --all
+if ($LASTEXITCODE -ne 0) {
+    Write-Error 'FAIL: cargo fmt failed.'
+    exit 1
+}
+Write-Host 'PASS: Formatting complete.' -ForegroundColor Green
+
+Write-Host ''
+Write-Host '--- Step 2: cargo clippy --all -- -D warnings ---' -ForegroundColor Cyan
+& cargo clippy --all -- -D warnings
+if ($LASTEXITCODE -ne 0) {
+    Write-Error 'FAIL: clippy reported errors. Fix them, then re-run.'
+    exit 1
+}
+Write-Host 'PASS: Clippy clean.' -ForegroundColor Green
+
+Write-Host ''
+Write-Host '=== ALL PRE-COMMIT CHECKS PASSED ===' -ForegroundColor Green
+Write-Host 'Safe to commit.'

scripts/rust-precommit.sh

@@ -0,0 +1,41 @@
+#!/usr/bin/env bash
+# Rust pre-commit checks for PET workspace.
+# Runs `cargo fmt --all` and `cargo clippy --all -- -D warnings`.
+# Exits non-zero on any failure so callers can gate commits.
+
+set -euo pipefail
+
+WORKSPACE="${1:-.}"
+cd "$WORKSPACE"
+
+echo "=== RUST PRE-COMMIT CHECKS ==="
+
+if ! command -v cargo &> /dev/null; then
+    if [ -f "$HOME/.cargo/env" ]; then
+        # shellcheck disable=SC1091
+        source "$HOME/.cargo/env"
+    else
+        echo "FAIL: cargo not found in PATH" >&2
+        exit 1
+    fi
+fi
+
+echo ""
+echo "--- Step 1: cargo fmt --all ---"
+if ! cargo fmt --all; then
+    echo "FAIL: cargo fmt failed." >&2
+    exit 1
+fi
+echo "PASS: Formatting complete."
+
+echo ""
+echo "--- Step 2: cargo clippy --all -- -D warnings ---"
+if ! cargo clippy --all -- -D warnings; then
+    echo "FAIL: clippy reported errors. Fix them, then re-run." >&2
+    exit 1
+fi
+echo "PASS: Clippy clean."
+
+echo ""
+echo "=== ALL PRE-COMMIT CHECKS PASSED ==="
+echo "Safe to commit."