From 46a575f48a05457b782fb21f7827d338c9b59320 Mon Sep 17 00:00:00 2001
From: Tim <hello@timsmart.co>
Date: Sat, 24 Aug 2024 00:02:02 +1200
Subject: [PATCH] fix nested Config.array (#3499)

---
 .changeset/tricky-mails-confess.md             |  5 +++++
 packages/effect/src/internal/configProvider.ts |  2 +-
 packages/effect/test/Config.test.ts            | 12 ++++++++++++
 3 files changed, 18 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/tricky-mails-confess.md

diff --git a/.changeset/tricky-mails-confess.md b/.changeset/tricky-mails-confess.md
new file mode 100644
index 0000000000..3b05e9e6ef
--- /dev/null
+++ b/.changeset/tricky-mails-confess.md
@@ -0,0 +1,5 @@
+---
+"effect": patch
+---
+
+fix nested Config.array, by ensuring path patches aren't applied twice in sequences
diff --git a/packages/effect/src/internal/configProvider.ts b/packages/effect/src/internal/configProvider.ts
index fe8a0f9227..772a922fd1 100644
--- a/packages/effect/src/internal/configProvider.ts
+++ b/packages/effect/src/internal/configProvider.ts
@@ -329,7 +329,7 @@ const fromFlatLoop = <A>(
             core.flatMap((indices) => {
               if (indices.length === 0) {
                 return core.suspend(() =>
-                  core.map(fromFlatLoop(flat, patchedPrefix, op.config, true), Arr.of)
+                  core.map(fromFlatLoop(flat, prefix, op.config, true), Arr.of)
                 ) as unknown as Effect.Effect<Array<A>, ConfigError.ConfigError>
               }
               return pipe(
diff --git a/packages/effect/test/Config.test.ts b/packages/effect/test/Config.test.ts
index 5b012a6440..00ec1ecc4c 100644
--- a/packages/effect/test/Config.test.ts
+++ b/packages/effect/test/Config.test.ts
@@ -557,4 +557,16 @@ describe("Config", () => {
     ))
     assert.strictEqual(result, "value")
   })
+
+  it("array nested", () => {
+    const result = Config.array(Config.number(), "ARRAY").pipe(
+      Effect.withConfigProvider(
+        ConfigProvider.fromMap(new Map([["NESTED.ARRAY", "1,2,3"]])).pipe(
+          ConfigProvider.nested("NESTED")
+        )
+      ),
+      Effect.runSync
+    )
+    assert.deepStrictEqual(result, [1, 2, 3])
+  })
 })