feat(cdp): shorten vercel log drain hashes to 22-char base64

Author: lricoy

nodejs/src/cdp/templates/_sources/vercel/__snapshots__/vercel_log_drain.template.test.ts.snap

@@ -3,7 +3,7 @@
 exports[`vercel log drain template should capture all Vercel log properties with snake_case naming 1`] = `
 [
   {
-    "distinct_id": "http_log_a2c746dc51d4d25aa95cd6a2ebb31af1f46ce475194e213adfcf9e2f7be982d0",
+    "distinct_id": "http_log_osdG3FHU0lqpXNai67Ma8f",
     "event": "$http_log",
     "properties": {
       "$current_url": "https://my-app.vercel.app/api/users?page=1",

nodejs/src/cdp/templates/_sources/vercel/vercel_log_drain.template.test.ts

@@ -25,7 +25,7 @@ describe('vercel log drain template', () => {
         expect(response.finished).toEqual(true)
         expect(response.capturedPostHogEvents).toHaveLength(1)
         expect(response.capturedPostHogEvents[0].event).toEqual('$http_log')
-        expect(response.capturedPostHogEvents[0].distinct_id).toMatch(/^http_log_[a-f0-9]{64}$/)
+        expect(response.capturedPostHogEvents[0].distinct_id).toMatch(/^http_log_[A-Za-z0-9+/]{22}$/)
         expect(response.capturedPostHogEvents[0].properties).toMatchObject({
             source: 'lambda',
             level: 'info',
@@ -218,7 +218,7 @@ describe('vercel log drain template', () => {
         )
 
         expect(response.error).toBeUndefined()
-        expect(response.capturedPostHogEvents[0].distinct_id).toMatch(/^http_log_[a-f0-9]{64}$/)
+        expect(response.capturedPostHogEvents[0].distinct_id).toMatch(/^http_log_[A-Za-z0-9+/]{22}$/)
     })
 
     it('should capture all Vercel log properties with snake_case naming', async () => {
@@ -306,7 +306,7 @@ describe('vercel log drain template', () => {
 
         expect(response.error).toBeUndefined()
         expect(response.capturedPostHogEvents).toHaveLength(1)
-        expect(response.capturedPostHogEvents[0].distinct_id).toMatch(/^http_log_[a-f0-9]{64}$/)
+        expect(response.capturedPostHogEvents[0].distinct_id).toMatch(/^http_log_[A-Za-z0-9+/]{22}$/)
         // Proxy fields should be null when proxy is missing
         expect(response.capturedPostHogEvents[0].properties.proxy_method).toBeNull()
     })
@@ -549,7 +549,7 @@ describe('vercel log drain template', () => {
             const id1Repeat = day1Repeat.capturedPostHogEvents[0].distinct_id
             const id2 = day2.capturedPostHogEvents[0].distinct_id
 
-            expect(id1).toMatch(/^http_log_[a-f0-9]{64}$/)
+            expect(id1).toMatch(/^http_log_[A-Za-z0-9+/]{22}$/)
             expect(id1Repeat).toBe(id1)
             expect(id2).not.toBe(id1)
             expect(day1.capturedPostHogEvents[0].properties.$distinct_id_strategy).toBe('rotating_salt')
@@ -585,7 +585,7 @@ describe('vercel log drain template', () => {
                 { request: createVercelRequest(vercelLogDrain) }
             )
 
-            expect(day1.capturedPostHogEvents[0].distinct_id).toMatch(/^http_log_[a-f0-9]{64}$/)
+            expect(day1.capturedPostHogEvents[0].distinct_id).toMatch(/^http_log_[A-Za-z0-9+/]{22}$/)
             expect(day2.capturedPostHogEvents[0].distinct_id).toBe(day1.capturedPostHogEvents[0].distinct_id)
             expect(rotated.capturedPostHogEvents[0].distinct_id).not.toBe(day1.capturedPostHogEvents[0].distinct_id)
             expect(day1.capturedPostHogEvents[0].properties.$distinct_id_strategy).toBe('fixed_salt')
@@ -641,7 +641,7 @@ describe('vercel log drain template', () => {
             )
 
             expect(response.error).toBeUndefined()
-            expect(response.capturedPostHogEvents[0].distinct_id).toMatch(/^http_log_[a-f0-9]{64}$/)
+            expect(response.capturedPostHogEvents[0].distinct_id).toMatch(/^http_log_[A-Za-z0-9+/]{22}$/)
             expect(response.capturedPostHogEvents[0].properties.$distinct_id_strategy).toBe('rotating_salt_fallback')
             expect(response.logs.map((l) => l.message)).toContainEqual(
                 expect.stringContaining('custom_template empty, falling back')

nodejs/src/cdp/templates/_sources/vercel/vercel_log_drain.template.ts

@@ -170,17 +170,24 @@ let strategy := inputs.distinct_id_strategy ?? 'rotating_salt'
 let activeStrategy := strategy
 let distinctId := ''
 
+// Hashed strategies emit a 22-char unpadded base64 prefix of sha256, matching
+// the visual format of PostHog cookieless distinct IDs (132 bits of entropy —
+// far more than needed for collision resistance, and short enough to be readable).
+fun shortHash(input) {
+    return substring(sha256(input, 'base64'), 1, 22)
+}
+
 if (strategy == 'rotating_salt') {
-    distinctId := f'http_log_{sha256Hex(f'{salt}:{day}:{clientIp}:{host}:{userAgent}')}'
+    distinctId := f'http_log_{shortHash(f'{salt}:{day}:{clientIp}:{host}:{userAgent}')}'
 } else if (strategy == 'fixed_salt') {
-    distinctId := f'http_log_{sha256Hex(f'{salt}:{clientIp}:{host}:{userAgent}')}'
+    distinctId := f'http_log_{shortHash(f'{salt}:{clientIp}:{host}:{userAgent}')}'
 } else if (strategy == 'ip') {
     distinctId := f'http_log_{clientIp}'
 } else if (strategy == 'custom') {
     let customTemplate := inputs.custom_template ?? ''
     if (empty(customTemplate)) {
         print('vercel log drain: custom_template empty, falling back to rotating_salt')
-        distinctId := f'http_log_{sha256Hex(f'{salt}:{day}:{clientIp}:{host}:{userAgent}')}'
+        distinctId := f'http_log_{shortHash(f'{salt}:{day}:{clientIp}:{host}:{userAgent}')}'
         activeStrategy := 'rotating_salt_fallback'
     } else {
         let result := customTemplate
@@ -195,7 +202,7 @@ if (strategy == 'rotating_salt') {
     }
 } else {
     // Unknown strategy value — treat as rotating_salt
-    distinctId := f'http_log_{sha256Hex(f'{salt}:{day}:{clientIp}:{host}:{userAgent}')}'
+    distinctId := f'http_log_{shortHash(f'{salt}:{day}:{clientIp}:{host}:{userAgent}')}'
     activeStrategy := 'rotating_salt'
 }