fix: prioritise main branch in canary detection

Author: danielroe

config/env.ts

@@ -39,13 +39,16 @@ export const prNumber = process.env.REVIEW_ID || process.env.VERCEL_GIT_PULL_REQ
 export const gitBranch = process.env.BRANCH || process.env.VERCEL_GIT_COMMIT_REF
 
 /**
- * Environment variable `VERCEL_ENV` provided by Vercel.
- * `production`, `preview`, `development`, or a custom environment name (e.g. `canary`).
- * @see {@link https://vercel.com/docs/environment-variables/system-environment-variables#VERCEL_ENV}
+ * Whether this is the canary environment (main.npmx.dev).
  *
- * Whether this is the canary custom Vercel environment (main.npmx.dev).
+ * Detected via the custom Vercel environment (`VERCEL_ENV === 'canary'`),
+ * or as a fallback, a production deploy from the `main` branch.
+ *
+ * @see {@link https://vercel.com/docs/environment-variables/system-environment-variables#VERCEL_ENV}
  */
-export const isCanary = process.env.VERCEL_ENV === 'canary'
+export const isCanary =
+  process.env.VERCEL_ENV === 'canary' ||
+  (process.env.VERCEL_ENV === 'production' && gitBranch === 'main')
 
 /**
  * Environment variable `CONTEXT` provided by Netlify.

test/unit/config/env.spec.ts

@@ -34,13 +34,22 @@ describe('isCanary', () => {
     expect(isCanary).toBe(true)
   })
 
+  it('returns true when VERCEL_ENV is "production" and branch is "main"', async () => {
+    vi.stubEnv('VERCEL_ENV', 'production')
+    vi.stubEnv('VERCEL_GIT_COMMIT_REF', 'main')
+    const { isCanary } = await import('../../../config/env')
+
+    expect(isCanary).toBe(true)
+  })
+
   it.each([
-    ['production', 'production'],
-    ['preview', 'preview'],
-    ['development', 'development'],
-    ['unset', undefined],
-  ])('returns false when VERCEL_ENV is %s', async (_label, value) => {
+    ['production (non-main branch)', 'production', 'v1.0.0'],
+    ['preview', 'preview', undefined],
+    ['development', 'development', undefined],
+    ['unset', undefined, undefined],
+  ])('returns false when VERCEL_ENV is %s', async (_label, value, branch) => {
     if (value !== undefined) vi.stubEnv('VERCEL_ENV', value)
+    if (branch !== undefined) vi.stubEnv('VERCEL_GIT_COMMIT_REF', branch)
     const { isCanary } = await import('../../../config/env')
 
     expect(isCanary).toBe(false)
@@ -98,7 +107,16 @@ describe('getEnv', () => {
     expect(result.env).toBe('preview')
   })
 
-  it('returns "release" for Vercel production deploys', async () => {
+  it('returns "canary" for Vercel production deploys from main branch', async () => {
+    vi.stubEnv('VERCEL_ENV', 'production')
+    vi.stubEnv('VERCEL_GIT_COMMIT_REF', 'main')
+    const { getEnv } = await import('../../../config/env')
+    const result = await getEnv(false)
+
+    expect(result.env).toBe('canary')
+  })
+
+  it('returns "release" for Vercel production deploys from non-main branch', async () => {
     vi.stubEnv('VERCEL_ENV', 'production')
     vi.stubEnv('VERCEL_GIT_COMMIT_REF', 'v1.0.0')
     const { getEnv } = await import('../../../config/env')