Make Windows package staging idempotent

CHANGELOG.md

@@ -32,6 +32,9 @@
   executable postinst/postrm scripts that refresh the desktop database.
   All behavior is opt-in per project key; projects without the keys build
   byte-identical installers to before.
+- Recreate the Windows package destination before copying release payloads, so
+  build/package/release retries over a dirty `dist/` tree are idempotent and
+  cannot retain stale files or fail with `copy-file: destination exists`.
 - Add leaf-loadable distribution identity helpers for the canonical manifest
   platform, architecture, installer-extension, and UTC RFC 3339 vocabulary.
   Release tooling and the managed updater now consume the same implementation

rivet-cli/package.rkt

@@ -172,6 +172,10 @@
         (regexp-match? pattern entry))))
 
 (define (copy-windows-release! stage destination)
+  ;; Packaging may be retried in the same workspace after a partial publish.
+  ;; Recreate the target so copy-file never collides with stale payloads and
+  ;; removed files from the new stage cannot survive in the package.
+  (remove-path! destination)
   (make-directory* destination)
   (for ([entry (in-list (directory-list stage))])
     (define source (build-path stage entry))
@@ -197,6 +201,9 @@
     (sign-windows-production! (build-path destination "RivetHost.exe") settings))
   destination)
 
+(module+ test-support
+  (provide copy-windows-release!))
+
 (define (package-linux! project stage name)
   (define destination
     (project-path project "dist" (linux-package-directory-name project)))

rivet/tests/package-freshness.rkt

@@ -7,7 +7,8 @@
 (require rackunit
          racket/file
          racket/runtime-path
-         racket/string)
+         racket/string
+         (submod "../../rivet-cli/package.rkt" test-support))
 
 (define-runtime-path repository-root "../..")
 
@@ -23,3 +24,37 @@
 (check-true (regexp-match? #px"clean-native[?][^)]*fresh-directory! build-dir"
                            build-source)
             "macOS package builds must recreate the Swift scratch tree")
+
+;; A retry over a dirty Windows package target must replace the old tree. This
+;; is the copy path whose previous create-only behavior raised "destination
+;; exists" after a failed or repeated release.
+(define temp-root (make-temporary-file "rivet-package-retry-~a" 'directory))
+(dynamic-wind
+  void
+  (lambda ()
+    (define stage (build-path temp-root "stage"))
+    (define destination (build-path temp-root "dist" "Example-windows-x64"))
+    (make-directory* (build-path stage "res"))
+    (call-with-output-file (build-path stage "RivetHost.exe")
+      #:exists 'truncate/replace
+      (lambda (out) (display "first" out)))
+    (call-with-output-file (build-path stage "res" "current.txt")
+      #:exists 'truncate/replace
+      (lambda (out) (display "current" out)))
+    (copy-windows-release! stage destination)
+
+    (call-with-output-file (build-path destination "stale.txt")
+      #:exists 'truncate/replace
+      (lambda (out) (display "stale" out)))
+    (call-with-output-file (build-path stage "RivetHost.exe")
+      #:exists 'truncate/replace
+      (lambda (out) (display "second" out)))
+    (copy-windows-release! stage destination)
+
+    (check-equal? (file->string (build-path destination "RivetHost.exe"))
+                  "second")
+    (check-true (file-exists? (build-path destination "res" "current.txt")))
+    (check-false (file-exists? (build-path destination "stale.txt"))))
+  (lambda ()
+    (when (directory-exists? temp-root)
+      (delete-directory/files temp-root))))