feat: add task workflow and asset downloads

supabase/schema.sql

@@ -15,6 +15,7 @@ create table if not exists assets (
 create table if not exists generation_jobs (
   id text primary key,
   owner_id text not null,
+  external_client_id text,
   capability text not null,
   provider text not null,
   req_key text not null,
@@ -28,10 +29,38 @@ create table if not exists generation_jobs (
   response_payload jsonb,
   error jsonb,
   retry_of text,
+  idempotency_key text,
+  idempotency_fingerprint text,
+  priority integer not null default 0,
+  attempts integer not null default 0,
+  max_attempts integer not null default 3,
+  scheduled_at timestamptz not null default now(),
+  locked_at timestamptz,
+  locked_by text,
+  started_at timestamptz,
+  completed_at timestamptz,
+  webhook_url text,
+  webhook_attempts integer not null default 0,
+  webhook_last_status jsonb,
   created_at timestamptz not null default now(),
   updated_at timestamptz not null default now()
 );
 
+alter table generation_jobs add column if not exists external_client_id text;
+alter table generation_jobs add column if not exists idempotency_key text;
+alter table generation_jobs add column if not exists idempotency_fingerprint text;
+alter table generation_jobs add column if not exists priority integer not null default 0;
+alter table generation_jobs add column if not exists attempts integer not null default 0;
+alter table generation_jobs add column if not exists max_attempts integer not null default 3;
+alter table generation_jobs add column if not exists scheduled_at timestamptz not null default now();
+alter table generation_jobs add column if not exists locked_at timestamptz;
+alter table generation_jobs add column if not exists locked_by text;
+alter table generation_jobs add column if not exists started_at timestamptz;
+alter table generation_jobs add column if not exists completed_at timestamptz;
+alter table generation_jobs add column if not exists webhook_url text;
+alter table generation_jobs add column if not exists webhook_attempts integer not null default 0;
+alter table generation_jobs add column if not exists webhook_last_status jsonb;
+
 create table if not exists usage_events (
   id text primary key,
   owner_id text not null,
@@ -56,4 +85,47 @@ create table if not exists projects (
 create index if not exists assets_owner_created_idx on assets(owner_id, created_at desc);
 create index if not exists generation_jobs_owner_created_idx on generation_jobs(owner_id, created_at desc);
 create index if not exists generation_jobs_status_idx on generation_jobs(status);
+create index if not exists generation_jobs_claim_idx on generation_jobs(status, scheduled_at, locked_at, priority desc);
+create index if not exists generation_jobs_external_client_idx on generation_jobs(owner_id, external_client_id, created_at desc);
+create unique index if not exists generation_jobs_idempotency_idx
+  on generation_jobs(owner_id, external_client_id, idempotency_key)
+  where external_client_id is not null and idempotency_key is not null;
 create index if not exists usage_events_owner_created_idx on usage_events(owner_id, created_at desc);
+
+create or replace function claim_generation_jobs(
+  p_worker_id text,
+  p_limit integer default 1,
+  p_lock_timeout_seconds integer default 300
+)
+returns setof generation_jobs
+language plpgsql
+as $$
+declare
+  v_now timestamptz := now();
+begin
+  return query
+  with candidates as (
+    select id
+    from generation_jobs
+    where status in ('queued', 'running')
+      and coalesce(scheduled_at, created_at) <= v_now
+      and (
+        locked_at is null
+        or locked_at < v_now - make_interval(secs => p_lock_timeout_seconds)
+      )
+    order by coalesce(priority, 0) desc, coalesce(scheduled_at, created_at) asc, created_at asc
+    limit greatest(1, least(coalesce(p_limit, 1), 20))
+    for update skip locked
+  ),
+  updated as (
+    update generation_jobs
+    set locked_at = v_now,
+        locked_by = p_worker_id,
+        started_at = coalesce(generation_jobs.started_at, v_now),
+        updated_at = v_now
+    where id in (select id from candidates)
+    returning generation_jobs.*
+  )
+  select * from updated;
+end;
+$$;