From f93ad2a8f0f5f048bfbd2bad9ba3237d30e323af Mon Sep 17 00:00:00 2001
From: Nic <162764842+Nic-Polumeyv@users.noreply.github.com>
Date: Fri, 17 Jul 2026 20:45:48 -0400
Subject: [PATCH] Allow skipping only same-file duplicates with skipDuplicates:
 "same-file", fixes #601

---
 README.md                                          | 7 ++++++-
 lib/parse-styles.js                                | 5 +++--
 test/fixtures/imports/same-file-dedup/a/shared.css | 1 +
 test/fixtures/imports/same-file-dedup/b/shared.css | 1 +
 test/fixtures/same-file-dedup.css                  | 3 +++
 test/fixtures/same-file-dedup.expected.css         | 2 ++
 test/import.js                                     | 9 +++++++++
 7 files changed, 25 insertions(+), 3 deletions(-)
 create mode 100644 test/fixtures/imports/same-file-dedup/a/shared.css
 create mode 100644 test/fixtures/imports/same-file-dedup/b/shared.css
 create mode 100644 test/fixtures/same-file-dedup.css
 create mode 100644 test/fixtures/same-file-dedup.expected.css

diff --git a/README.md b/README.md
index 9c96cf2..0bf2617 100644
--- a/README.md
+++ b/README.md
@@ -180,7 +180,7 @@ promised content.
 
 #### `skipDuplicates`
 
-Type: `Boolean`  
+Type: `Boolean` or `"same-file"`  
 Default: `true`
 
 By default, similar files (based on the same content) are being skipped.
@@ -188,6 +188,11 @@ It's to optimize output and skip similar files like `normalize.css` for example.
 If this behavior is not what you want, just set this option to `false` to
 disable it.
 
+Setting this option to `"same-file"` skips repeated imports of the same file,
+but not different files sharing the same content. Use it when imported files
+contain at-rules whose paths resolve relative to the file's own location, so
+that byte-identical files at different paths are not actually duplicates.
+
 #### `addModulesDirectories`
 
 Type: `Array`  
diff --git a/lib/parse-styles.js b/lib/parse-styles.js
index 766de9c..ec0e44b 100644
--- a/lib/parse-styles.js
+++ b/lib/parse-styles.js
@@ -178,8 +178,9 @@ async function loadImportContent(
   }
 
   // skip previous imported files not containing @import rules
+  // (content dedup does not apply in "same-file" mode)
   if (
-    options.skipDuplicates &&
+    options.skipDuplicates === true &&
     state.hashFiles[content]?.[stmtDuplicateCheckKey]
   ) {
     return
@@ -196,7 +197,7 @@ async function loadImportContent(
   const styles = importedResult.root
   result.messages = result.messages.concat(importedResult.messages)
 
-  if (options.skipDuplicates) {
+  if (options.skipDuplicates === true) {
     const hasImport = styles.some(child => {
       return child.type === "atrule" && child.name === "import"
     })
diff --git a/test/fixtures/imports/same-file-dedup/a/shared.css b/test/fixtures/imports/same-file-dedup/a/shared.css
new file mode 100644
index 0000000..6abac48
--- /dev/null
+++ b/test/fixtures/imports/same-file-dedup/a/shared.css
@@ -0,0 +1 @@
+shared {}
diff --git a/test/fixtures/imports/same-file-dedup/b/shared.css b/test/fixtures/imports/same-file-dedup/b/shared.css
new file mode 100644
index 0000000..6abac48
--- /dev/null
+++ b/test/fixtures/imports/same-file-dedup/b/shared.css
@@ -0,0 +1 @@
+shared {}
diff --git a/test/fixtures/same-file-dedup.css b/test/fixtures/same-file-dedup.css
new file mode 100644
index 0000000..ef02919
--- /dev/null
+++ b/test/fixtures/same-file-dedup.css
@@ -0,0 +1,3 @@
+@import "same-file-dedup/a/shared.css";
+@import "same-file-dedup/b/shared.css";
+@import "same-file-dedup/a/shared.css";
diff --git a/test/fixtures/same-file-dedup.expected.css b/test/fixtures/same-file-dedup.expected.css
new file mode 100644
index 0000000..572363e
--- /dev/null
+++ b/test/fixtures/same-file-dedup.expected.css
@@ -0,0 +1,2 @@
+shared {}
+shared {}
diff --git a/test/import.js b/test/import.js
index e2a2bd1..6fc22c5 100644
--- a/test/import.js
+++ b/test/import.js
@@ -46,6 +46,15 @@ test(
 
 test("should import stylesheets with same content", checkFixture, "same")
 
+test(
+  "should only skip same-file duplicates with skipDuplicates: same-file",
+  checkFixture,
+  "same-file-dedup",
+  {
+    skipDuplicates: "same-file",
+  },
+)
+
 test("should ignore & adjust external import", checkFixture, "ignore")
 
 test("should not fail with only one absolute import", t => {