From 4d324ecc648bc978214c4999840e5be767517aef Mon Sep 17 00:00:00 2001
From: Thomas Bouldin <inlined@google.com>
Date: Wed, 15 Jul 2026 21:37:29 -0700
Subject: [PATCH 1/2] feat: add built-in functionRegion parameter for region

### Description
GCF v2 does not include the FUNCTION_REGION environment variable by default, which can break some workflows. In particular, Firebase Extensions may depend on this variable to target callable or task queue functions in the same region. This change adds the `functionRegion` built-in parameter (and `region` alias) to the SDK.

### Scenarios Tested
- Unit tests for value extraction and CEL representation.

### Sample Commands
- N/A (SDK library)
---
 spec/params/params.spec.ts | 18 ++++++++++++++++++
 src/params/index.ts        | 13 +++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/spec/params/params.spec.ts b/spec/params/params.spec.ts
index 19d18c83a..df2c39dcd 100644
--- a/spec/params/params.spec.ts
+++ b/spec/params/params.spec.ts
@@ -139,6 +139,16 @@ describe("Params value extraction", () => {
     delete process.env.FIREBASE_CONFIG;
   });
 
+  it("extracts the special case FUNCTION_REGION / functionRegion / region from process.env", () => {
+    process.env.FUNCTION_REGION = "us-east1";
+    expect(params.functionRegion.value()).to.equal("us-east1");
+    expect(params.region.value()).to.equal("us-east1");
+
+    delete process.env.FUNCTION_REGION;
+    expect(params.functionRegion.value()).to.equal("");
+    expect(params.region.value()).to.equal("");
+  });
+
   it("falls back on the javascript zero values in case of type mismatch", () => {
     const stringToInt = params.defineInt("A_STRING");
     expect(stringToInt.value()).to.equal(0);
@@ -378,6 +388,14 @@ describe("Params as CEL", () => {
     expect(params.storageBucket.equals(str).toCEL()).to.equal(
       `{{ params.STORAGE_BUCKET == params.A_STRING }}`
     );
+    expect(params.functionRegion.toCEL()).to.equal(`{{ params.FUNCTION_REGION }}`);
+    expect(params.functionRegion.equals("foo").toCEL()).to.equal(
+      `{{ params.FUNCTION_REGION == "foo" }}`
+    );
+    expect(params.functionRegion.equals(str).toCEL()).to.equal(
+      `{{ params.FUNCTION_REGION == params.A_STRING }}`
+    );
+    expect(params.region.toCEL()).to.equal(`{{ params.FUNCTION_REGION }}`);
   });
 
   it("identity expressions", () => {
diff --git a/src/params/index.ts b/src/params/index.ts
index e824f61fa..fc6341dba 100644
--- a/src/params/index.ts
+++ b/src/params/index.ts
@@ -138,6 +138,19 @@ export const storageBucket: Param<string> = new InternalExpression(
   "STORAGE_BUCKET",
   (env: NodeJS.ProcessEnv) => JSON.parse(env.FIREBASE_CONFIG || "{}")?.storageBucket || ""
 );
+/**
+ * A built-in parameter that resolves to the Cloud region, without prompting
+ * the deployer.
+ */
+export const functionRegion: Param<string> = new InternalExpression(
+  "FUNCTION_REGION",
+  (env: NodeJS.ProcessEnv) => env.FUNCTION_REGION || ""
+);
+/**
+ * A built-in parameter that resolves to the Cloud region, without prompting
+ * the deployer. Alias for {@link functionRegion}.
+ */
+export const region: Param<string> = functionRegion;
 
 /**
  * Declares a secret param, that will persist values only in Cloud Secret Manager.

From b94dfb100246891ec00424063c763b4b6349614f Mon Sep 17 00:00:00 2001
From: Thomas Bouldin <inlined@google.com>
Date: Wed, 15 Jul 2026 22:14:08 -0700
Subject: [PATCH 2/2] chore: wrap test assertion in try...finally

---
 spec/params/params.spec.ts | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/spec/params/params.spec.ts b/spec/params/params.spec.ts
index df2c39dcd..a589840b0 100644
--- a/spec/params/params.spec.ts
+++ b/spec/params/params.spec.ts
@@ -140,11 +140,13 @@ describe("Params value extraction", () => {
   });
 
   it("extracts the special case FUNCTION_REGION / functionRegion / region from process.env", () => {
-    process.env.FUNCTION_REGION = "us-east1";
-    expect(params.functionRegion.value()).to.equal("us-east1");
-    expect(params.region.value()).to.equal("us-east1");
-
-    delete process.env.FUNCTION_REGION;
+    try {
+      process.env.FUNCTION_REGION = "us-east1";
+      expect(params.functionRegion.value()).to.equal("us-east1");
+      expect(params.region.value()).to.equal("us-east1");
+    } finally {
+      delete process.env.FUNCTION_REGION;
+    }
     expect(params.functionRegion.value()).to.equal("");
     expect(params.region.value()).to.equal("");
   });