fix: resolve latest before cache check to avoid stale cargo-rail reuse

Author: loadingalias

README.md

@@ -42,7 +42,7 @@ jobs:
 
 | Input | Default | Description |
 |---|---|---|
-| `version` | `latest` | `cargo-rail` version to install |
+| `version` | `latest` | `cargo-rail` version to install (`latest` resolves to the newest GitHub release tag each run) |
 | `checksum` | `required` | `required`, `if-available`, or `off` |
 | `since` | auto | Git ref for planner comparison |
 | `args` | `""` | Extra planner args (see below) |
@@ -135,7 +135,7 @@ The action tries installation methods in this order:
 
 1. **Cached binary** (fastest) — uses GitHub Actions cache (`actions/cache`)
    - Why: Subsequent runs on same runner are instant (no download)
-   - Cache key includes version + platform, auto-invalidates on version change
+   - Cache reuse requires exact version match; when `version: latest`, the action resolves latest first, then compares
 
 2. **Release binary** (fast) — downloads from GitHub Releases
    - Why: Pre-built binaries for all supported platforms, verified against `SHA256SUMS`

action.yaml

@@ -160,10 +160,22 @@ runs:
       run: |
         set -euo pipefail
 
-        # Check if already installed and meets version requirement
+        # Resolve version (latest -> actual version number)
+        VERSION="$REQUESTED_VERSION"
+        if [[ "$VERSION" == "latest" ]]; then
+          RESOLVED_VERSION=$(gh api repos/loadingalias/cargo-rail/releases/latest --jq '.tag_name' 2>/dev/null | sed 's/^v//' || true)
+          if [[ -n "$RESOLVED_VERSION" ]]; then
+            VERSION="$RESOLVED_VERSION"
+          else
+            echo "::warning::Could not determine latest version from GitHub API"
+            VERSION="latest"
+          fi
+        fi
+
+        # Check if already installed and matches resolved version requirement
         if command -v cargo-rail &>/dev/null; then
           INSTALLED_VERSION=$(cargo-rail rail --version 2>/dev/null | grep -oE '[0-9]+\.[0-9]+\.[0-9]+' | head -1 || echo "unknown")
-          if [[ "$REQUESTED_VERSION" == "latest" || "$INSTALLED_VERSION" == "$REQUESTED_VERSION" ]]; then
+          if [[ "$VERSION" != "latest" && "$INSTALLED_VERSION" == "$VERSION" ]]; then
             echo "cargo-rail $INSTALLED_VERSION already installed"
             echo "method=cached" >> "$GITHUB_OUTPUT"
             echo "version=$INSTALLED_VERSION" >> "$GITHUB_OUTPUT"
@@ -188,15 +200,6 @@ runs:
             ;;
         esac
 
-        # Resolve version (latest -> actual version number)
-        VERSION="$REQUESTED_VERSION"
-        if [[ "$VERSION" == "latest" ]]; then
-          VERSION=$(gh api repos/loadingalias/cargo-rail/releases/latest --jq '.tag_name' 2>/dev/null | sed 's/^v//' || echo "")
-          if [[ -z "$VERSION" ]]; then
-            echo "::warning::Could not determine latest version from GitHub API"
-          fi
-        fi
-
         # Fast path: Pre-built binary download
         if [[ -n "$TARGET" && -n "$VERSION" ]]; then
           echo "Attempting binary download: cargo-rail v$VERSION for $TARGET"