feat: use postgres

mail/docs/flows.md

@@ -6,22 +6,22 @@
 sequenceDiagram
     participant Auth as Auth / Session Service
     participant Mail as Mail Service
-    participant Redis
+    participant Postgres
     participant Scheduler
     participant SMTP as Provider
 
     Auth->>Mail: POST /api/v1/internal/login-code-deliveries + Idempotency-Key
     Mail->>Mail: validate request and idempotency scope
     alt MAIL_SMTP_MODE = stub
-        Mail->>Redis: persist delivery as suppressed
+        Mail->>Postgres: persist delivery as suppressed
         Mail-->>Auth: 200 {outcome=suppressed}
     else MAIL_SMTP_MODE = smtp
-        Mail->>Redis: persist delivery as queued + attempt #1 scheduled
+        Mail->>Postgres: persist delivery as queued + attempt #1 scheduled
         Mail-->>Auth: 200 {outcome=sent}
-        Scheduler->>Redis: claim due attempt
+        Scheduler->>Postgres: claim due attempt (FOR UPDATE SKIP LOCKED)
         Scheduler->>SMTP: send rendered auth mail
         SMTP-->>Scheduler: accepted or classified failure
-        Scheduler->>Redis: commit sent / retry / failed / dead_letter
+        Scheduler->>Postgres: commit sent / retry / failed / dead_letter
     end
 ```
 
@@ -36,16 +36,17 @@ sequenceDiagram
     participant Stream as Redis Stream mail:delivery_commands
     participant Consumer as Command consumer
     participant Mail as Mail Service
+    participant Postgres
     participant Redis
 
     Notify->>Stream: XADD generic command
     Consumer->>Stream: XREAD from last stored offset
     Consumer->>Mail: decode and validate command
     alt malformed or conflicting command
-        Mail->>Redis: record malformed command entry
+        Mail->>Postgres: record malformed command entry
         Consumer->>Redis: save stream offset
     else valid command
-        Mail->>Redis: persist delivery + first attempt + optional payload bundle
+        Mail->>Postgres: persist delivery + first attempt + optional payload bundle
         Consumer->>Redis: save stream offset
     end
 ```
@@ -55,29 +56,29 @@ sequenceDiagram
 ```mermaid
 sequenceDiagram
     participant Scheduler
-    participant Redis
+    participant Postgres
     participant Worker as Attempt worker
     participant SMTP as Provider
 
-    Scheduler->>Redis: find next due delivery
-    Scheduler->>Redis: load work item
+    Scheduler->>Postgres: find next due delivery (next_attempt_at <= now)
+    Scheduler->>Postgres: load work item (delivery + active attempt)
     alt template delivery not yet rendered
-        Scheduler->>Redis: render and store materialized content
+        Scheduler->>Postgres: render and store materialized content
     end
-    Scheduler->>Redis: claim scheduled attempt
+    Scheduler->>Postgres: claim scheduled attempt (FOR UPDATE SKIP LOCKED)
     Scheduler->>Worker: enqueue claimed work
     Worker->>SMTP: send materialized message
     SMTP-->>Worker: accepted / suppressed / transient_failure / permanent_failure
     alt accepted
-        Worker->>Redis: commit sent + provider_accepted
+        Worker->>Postgres: commit sent + provider_accepted
     else suppressed
-        Worker->>Redis: commit suppressed + provider_rejected
+        Worker->>Postgres: commit suppressed + provider_rejected
     else transient failure before retry budget ends
-        Worker->>Redis: commit transport_failed|timed_out + next scheduled attempt
+        Worker->>Postgres: commit transport_failed|timed_out + next scheduled attempt
     else retry budget exhausted
-        Worker->>Redis: commit dead_letter + dead-letter entry
+        Worker->>Postgres: commit dead_letter + dead-letter entry
     else permanent failure
-        Worker->>Redis: commit failed + provider_rejected
+        Worker->>Postgres: commit failed + provider_rejected
     end
 ```
 
@@ -87,12 +88,12 @@ sequenceDiagram
 sequenceDiagram
     participant Ops as Trusted operator
     participant Mail as Mail Service
-    participant Redis
+    participant Postgres
 
     Ops->>Mail: POST /api/v1/internal/deliveries/{delivery_id}/resend
-    Mail->>Redis: load original delivery and optional payload bundle
+    Mail->>Postgres: load original delivery and optional payload bundle
     Mail->>Mail: verify original status is terminal
-    Mail->>Redis: create clone delivery with source=operator_resend
+    Mail->>Postgres: create clone delivery with source=operator_resend
     Mail-->>Ops: 200 {delivery_id=<clone>}
 ```