gabsurd

-- Absurd installs a Postgres-native durable workflow system that can be dropped
-- into an existing database.
--
-- It bootstraps the `absurd` schema and required extensions so that jobs, runs,
-- checkpoints, and workflow events all live alongside application data without
-- external services.
--
-- Each queue is materialized as its own set of tables that share a prefix:
-- * `t_` for tasks (what is to be run)
-- * `r_` for runs (attempts to run a task)
-- * `c_` for checkpoints (saved states)
-- * `e_` for emitted events
-- * `w_` for wait registrations
-- * `i_` for idempotency keys (partitioned queues only)
--
-- `create_queue`, `drop_queue`, and `list_queues` provide the management
-- surface for provisioning queues safely.
--
-- Task execution flows through `spawn_task`, which records the logical task and
-- its first run, and `claim_task`, which hands work to workers with leasing
-- semantics, state transitions, and cancellation checks.  Runtime routines
-- such as `complete_run`, `schedule_run`, and `fail_run` advance or retry work,
-- enforce attempt accounting, and keep the task and run tables synchronized.
--
-- Long-running or event-driven workflows rely on lightweight persistence
-- primitives.  Checkpoint helpers (`set_task_checkpoint_state`,
-- `get_task_checkpoint_state`, `get_task_checkpoint_states`) write arbitrary
-- JSON payloads keyed by task and step, while `await_event` and `emit_event`
-- coordinate sleepers and external signals so that tasks can suspend and resume
-- without losing context.  Events are uniquely indexed and use first-write-wins
-- semantics: the first emission per name is cached, later emits are ignored.

create extension if not exists "uuid-ossp";

create schema if not exists absurd;

-- Returns either the actual current timestamp or a fake one if
-- the session sets `absurd.fake_now`.  This lets tests control time.
create function absurd.current_time ()
  returns timestamptz
  language plpgsql
  volatile
as $$
declare
  v_fake text;
begin
  v_fake := current_setting('absurd.fake_now', true);
  if v_fake is not null and length(trim(v_fake)) > 0 then
    return v_fake::timestamptz;
  end if;

  return clock_timestamp();
end;
$$;

create table if not exists absurd.queues (
  queue_name text primary key,
  created_at timestamptz not null default absurd.current_time(),
  storage_mode text not null default 'unpartitioned'
    check (storage_mode in ('unpartitioned', 'partitioned')),
  default_partition text not null default 'enabled'
    check (default_partition in ('enabled', 'disabled')),
  partition_lookahead interval not null default interval '28 days'
    check (partition_lookahead >= interval '0 seconds'),
  partition_lookback interval not null default interval '1 day'
    check (partition_lookback >= interval '0 seconds'),
  cleanup_ttl interval not null default interval '30 days'
    check (cleanup_ttl >= interval '0 seconds'),
  cleanup_limit integer not null default 1000
    check (cleanup_limit >= 1),
  detach_mode text not null default 'none'
    check (detach_mode in ('none', 'empty')),
  detach_min_age interval not null default interval '30 days'
    check (detach_min_age >= interval '0 seconds')
);

-- Returns the Absurd schema release version baked into this SQL file.
-- During development this is usually "main" and release automation replaces
-- it with the actual tag version.

create or replace function absurd.get_schema_version ()
  returns text
  language sql
as $$
  select 'main'::text;
$$;

-- Queue names are used in generated table/index identifiers.
-- We intentionally cap UTF-8 byte length so generated explicit index names
-- (for instance r_<queue>_sai) stay within PostgreSQL's 63-byte identifier
-- limit. Character set is otherwise delegated to PostgreSQL quoted-ident rules.
create function absurd.validate_queue_name (p_queue_name text)
  returns text
  language plpgsql
as $$
begin
  if p_queue_name is null or p_queue_name = '' then
    raise exception 'Queue name must be provided';
  end if;

  if octet_length(p_queue_name) > 57 then
    raise exception 'Queue name "%" is too long (max 57 bytes).', p_queue_name;
  end if;

  return p_queue_name;
end;
$$;

create function absurd.ensure_queue_tables (p_queue_name text)
  returns void
  language plpgsql
as $$
declare
  v_storage_mode text := 'unpartitioned';
  v_t_suffix text;
  v_r_suffix text;
  v_c_suffix text;
  v_w_suffix text;
  v_t_idempotency_def text;
begin
  perform absurd.validate_queue_name(p_queue_name);

  select storage_mode into v_storage_mode
  from absurd.queues
  where queue_name = p_queue_name;

  v_storage_mode := coalesce(v_storage_mode, 'unpartitioned');

  if v_storage_mode not in ('unpartitioned', 'partitioned') then
    raise exception 'Unsupported queue storage mode "%"', v_storage_mode;
  end if;

  if v_storage_mode = 'partitioned' then
    v_t_suffix := 'partition by range (task_id)';
    v_r_suffix := 'partition by range (run_id)';
    v_c_suffix := 'partition by range (task_id)';
    v_w_suffix := 'partition by range (run_id)';
    v_t_idempotency_def := 'idempotency_key text';
  else
    v_t_suffix := 'with (fillfactor=70)';
    v_r_suffix := 'with (fillfactor=70)';
    v_c_suffix := 'with (fillfactor=70)';
    v_w_suffix := '';
    v_t_idempotency_def := 'idempotency_key text unique';
  end if;

  execute format(
    'create table if not exists absurd.%I (
        task_id uuid primary key,
        task_name text not null,
        params jsonb not null,
        headers jsonb,
        retry_strategy jsonb,
        max_attempts integer,
        cancellation jsonb,
        enqueue_at timestamptz not null default absurd.current_time(),
        first_started_at timestamptz,
        state text not null check (state in (''pending'', ''running'', ''sleeping'', ''completed'', ''failed'', ''cancelled'')),
        attempts integer not null default 0,
        last_attempt_run uuid,
        completed_payload jsonb,
        cancelled_at timestamptz,
        %s
     ) %s',
    't_' || p_queue_name,
    v_t_idempotency_def,
    v_t_suffix
  );

  execute format(
    'create table if not exists absurd.%I (
        run_id uuid primary key,
        task_id uuid not null,
        attempt integer not null,
        state text not null check (state in (''pending'', ''running'', ''sleeping'', ''completed'', ''failed'', ''cancelled'')),
        claimed_by text,
        claim_expires_at timestamptz,
        available_at timestamptz not null,
        wake_event text,
        event_payload jsonb,
        started_at timestamptz,
        completed_at timestamptz,
        failed_at timestamptz,
        result jsonb,
        failure_reason jsonb,
        created_at timestamptz not null default absurd.current_time()
     ) %s',
    'r_' || p_queue_name,
    v_r_suffix
  );

  execute format(
    'create table if not exists absurd.%I (
        task_id uuid not null,
        checkpoint_name text not null,
        state jsonb,
        status text not null default ''committed'',
        owner_run_id uuid,
        updated_at timestamptz not null default absurd.current_time(),
        primary key (task_id, checkpoint_name)
     ) %s',
    'c_' || p_queue_name,
    v_c_suffix
  );

  execute format(
    'create table if not exists absurd.%I (
        event_name text primary key,
        payload jsonb,
        emitted_at timestamptz not null default absurd.current_time()
     )',
    'e_' || p_queue_name
  );

  execute format(
    'create table if not exists absurd.%I (
        task_id uuid not null,
        run_id uuid not null,
        step_name text not null,
        event_name text not null,
        timeout_at timestamptz,
        created_at timestamptz not null default absurd.current_time(),
        primary key (run_id, step_name)
     ) %s',
    'w_' || p_queue_name,
    v_w_suffix
  );

  if v_storage_mode = 'partitioned' then
    execute format(
      'create table if not exists absurd.%I (
          idempotency_key text primary key,
          task_id uuid not null
       )',
      'i_' || p_queue_name
    );
  end if;

  execute format(
    'create index if not exists %I on absurd.%I (state, available_at)',
    ('r_' || p_queue_name) || '_sai',
    'r_' || p_queue_name
  );

  execute format(
    'create index if not exists %I on absurd.%I (task_id)',
    ('r_' || p_queue_name) || '_ti',
    'r_' || p_queue_name
  );

  execute format(
    'create index if not exists %I on absurd.%I (claim_expires_at)
      where state = ''running''
        and claim_expires_at is not null',
    ('r_' || p_queue_name) || '_cei',
    'r_' || p_queue_name
  );

  execute format(
    'create index if not exists %I on absurd.%I (event_name)',
    ('w_' || p_queue_name) || '_eni',
    'w_' || p_queue_name
  );

  execute format(
    'create index if not exists %I on absurd.%I (task_id)',
    ('w_' || p_queue_name) || '_ti',
    'w_' || p_queue_name
  );

  execute format(
    'create index if not exists %I on absurd.%I (emitted_at)',
    ('e_' || p_queue_name) || '_eai',
    'e_' || p_queue_name
  );

  if v_storage_mode = 'partitioned' then
    execute format(
      'create index if not exists %I on absurd.%I (task_id)',
      ('i_' || p_queue_name) || '_ti',
      'i_' || p_queue_name
    );

    perform absurd.ensure_partitions(p_queue_name);
  end if;
end;
$$;

-- Creates the queue with the given name and storage mode.
--
-- Existing queues are idempotent as long as the requested mode matches.
create function absurd.create_queue (
  p_queue_name text,
  p_storage_mode text
)
  returns void
  language plpgsql
as $$
declare
  v_storage_mode text;
  v_existing_mode text;
begin
  p_queue_name := absurd.validate_queue_name(p_queue_name);

  v_storage_mode := lower(trim(coalesce(p_storage_mode, '')));
  if v_storage_mode not in ('unpartitioned', 'partitioned') then
    raise exception 'Unsupported queue storage mode "%"', p_storage_mode;
  end if;

  insert into absurd.queues (queue_name, storage_mode)
  values (p_queue_name, v_storage_mode)
  on conflict (queue_name) do nothing;

  select storage_mode into v_existing_mode
  from absurd.queues
  where queue_name = p_queue_name;

  if v_existing_mode is null then
    raise exception 'Queue "%" was not found after create attempt', p_queue_name;
  end if;

  if v_existing_mode <> v_storage_mode then
    raise exception 'Queue "%" already exists with storage mode "%"', p_queue_name, v_existing_mode;
  end if;

  perform absurd.ensure_queue_tables(p_queue_name);
end;
$$;

-- Creates an unpartitioned queue (backward-compatible API).
create or replace function absurd.create_queue (p_queue_name text)
  returns void
  language plpgsql
as $$
begin
  perform absurd.create_queue(p_queue_name, 'unpartitioned');
end;
$$;

-- Drop a queue if it exists.
-- We intentionally don't validate the provided name here so legacy queues
-- created under older naming rules can still be removed.
create function absurd.drop_queue (p_queue_name text)
  returns void
  language plpgsql
as $$
declare
  v_existing_queue text;
begin
  select queue_name into v_existing_queue
  from absurd.queues
  where queue_name = p_queue_name;

  if v_existing_queue is null then
    return;
  end if;

  -- Remove queue-scoped maintenance jobs only when pg_cron is available.
  if to_regclass('cron.job') is not null and exists (
    select 1
    from pg_proc p
    join pg_namespace n on n.oid = p.pronamespace
    where n.nspname = 'cron'
      and p.proname = 'unschedule'
  ) then
    perform absurd.disable_cron(p_queue_name);
  end if;

  execute format('drop table if exists absurd.%I cascade', 'i_' || p_queue_name);
  execute format('drop table if exists absurd.%I cascade', 'w_' || p_queue_name);
  execute format('drop table if exists absurd.%I cascade', 'e_' || p_queue_name);
  execute format('drop table if exists absurd.%I cascade', 'c_' || p_queue_name);
  execute format('drop table if exists absurd.%I cascade', 'r_' || p_queue_name);
  execute format('drop table if exists absurd.%I cascade', 't_' || p_queue_name);

  delete from absurd.queues where queue_name = p_queue_name;
end;
$$;

-- Lists all queues that currently exist.
create function absurd.list_queues ()
  returns table (queue_name text)
  language sql
as $$
  select queue_name from absurd.queues order by queue_name;
$$;

-- Returns queue maintenance policy metadata.
create function absurd.get_queue_policy (
  p_queue_name text
)
  returns table (
    queue_name text,
    storage_mode text,
    default_partition text,
    partition_lookahead interval,
    partition_lookback interval,
    cleanup_ttl interval,
    cleanup_limit integer,
    detach_mode text,
    detach_min_age interval
  )
  language sql
as $$
  select
    q.queue_name,
    q.storage_mode,
    q.default_partition,
    q.partition_lookahead,
    q.partition_lookback,
    q.cleanup_ttl,
    q.cleanup_limit,
    q.detach_mode,
    q.detach_min_age
  from absurd.queues q
  where q.queue_name = p_queue_name;
$$;

-- Updates queue maintenance policy metadata.
--
-- p_policy accepts optional keys:
-- * partition_lookahead (interval text)
-- * partition_lookback (interval text)
-- * cleanup_ttl (interval text, >= 0)
-- * cleanup_limit (integer >= 1)
-- * detach_mode ('none' | 'empty')
-- * detach_min_age (interval text)
-- * default_partition ('enabled' | 'disabled')
create function absurd.set_queue_policy (
  p_queue_name text,
  p_policy jsonb
)
  returns void
  language plpgsql
as $$
declare
  v_policy jsonb := coalesce(p_policy, '{}'::jsonb);
  v_unknown_key text;
  v_exists boolean := false;
  v_storage_mode text;
  v_default_partition text;
  v_previous_default_partition text;
  v_parent_prefix text;
  v_parent_table text;
  v_default_table text;
  v_default_attached boolean;
  v_default_has_rows boolean;

  v_partition_lookahead interval;
  v_partition_lookback interval;
  v_cleanup_ttl interval;
  v_cleanup_limit integer;
  v_detach_mode text;
  v_detach_min_age interval;
begin
  p_queue_name := absurd.validate_queue_name(p_queue_name);

  if jsonb_typeof(v_policy) <> 'object' then
    raise exception 'Queue policy must be a JSON object';
  end if;

  select k.key
    into v_unknown_key
    from jsonb_object_keys(v_policy) as k(key)
   where k.key not in (
      'partition_lookahead',
      'partition_lookback',
      'cleanup_ttl',
      'cleanup_limit',
      'detach_mode',
      'detach_min_age',
      'default_partition'
   )
   limit 1;

  if v_unknown_key is not null then
    raise exception 'Unsupported queue policy key "%"', v_unknown_key;
  end if;

  select exists (
    select 1
    from absurd.queues
    where queue_name = p_queue_name
  )
  into v_exists;

  if not v_exists then
    raise exception 'Queue "%" does not exist', p_queue_name;
  end if;

  select
    storage_mode,
    default_partition,
    partition_lookahead,
    partition_lookback,
    cleanup_ttl,
    cleanup_limit,
    detach_mode,
    detach_min_age
  into
    v_storage_mode,
    v_default_partition,
    v_partition_lookahead,
    v_partition_lookback,
    v_cleanup_ttl,
    v_cleanup_limit,
    v_detach_mode,
    v_detach_min_age
  from absurd.queues
  where queue_name = p_queue_name
  for update;

  if v_policy ? 'partition_lookahead' then
    v_partition_lookahead := (v_policy->>'partition_lookahead')::interval;
  end if;

  if v_policy ? 'partition_lookback' then
    v_partition_lookback := (v_policy->>'partition_lookback')::interval;
  end if;

  if v_policy ? 'cleanup_ttl' then
    v_cleanup_ttl := (v_policy->>'cleanup_ttl')::interval;
  end if;

  if v_policy ? 'cleanup_limit' then
    v_cleanup_limit := (v_policy->>'cleanup_limit')::integer;
  end if;

  if v_policy ? 'detach_mode' then
    v_detach_mode := lower(trim(coalesce(v_policy->>'detach_mode', '')));
  end if;

  if v_policy ? 'detach_min_age' then
    v_detach_min_age := (v_policy->>'detach_min_age')::interval;
  end if;

  v_previous_default_partition := v_default_partition;

  if v_policy ? 'default_partition' then
    v_default_partition := lower(trim(coalesce(v_policy->>'default_partition', '')));
  end if;

  if v_partition_lookahead < interval '0 seconds' then
    raise exception 'partition_lookahead must be non-negative';
  end if;

  if v_partition_lookback < interval '0 seconds' then
    raise exception 'partition_lookback must be non-negative';
  end if;

  if v_cleanup_ttl < interval '0 seconds' then
    raise exception 'cleanup_ttl must be non-negative';
  end if;

  if v_cleanup_limit < 1 then
    raise exception 'cleanup_limit must be at least 1';
  end if;

  if v_detach_mode not in ('none', 'empty') then
    raise exception 'Unsupported detach mode "%"', v_detach_mode;
  end if;

  if v_detach_min_age < interval '0 seconds' then
    raise exception 'detach_min_age must be non-negative';
  end if;

  if v_default_partition not in ('enabled', 'disabled') then
    raise exception 'Unsupported default_partition mode "%"', v_default_partition;
  end if;

  if v_storage_mode <> 'partitioned' and v_policy ? 'default_partition' then
    raise exception 'default_partition policy is only supported for partitioned queues';
  end if;

  update absurd.queues
     set default_partition = v_default_partition,
         partition_lookahead = v_partition_lookahead,
         partition_lookback = v_partition_lookback,
         cleanup_ttl = v_cleanup_ttl,
         cleanup_limit = v_cleanup_limit,
         detach_mode = v_detach_mode,
         detach_min_age = v_detach_min_age
   where queue_name = p_queue_name;

  if v_storage_mode = 'partitioned'
     and v_previous_default_partition <> v_default_partition then
    if v_default_partition = 'enabled' then
      perform absurd.ensure_partitions(p_queue_name);
    else
      foreach v_parent_prefix in array array['t', 'r', 'c', 'w'] loop
        v_parent_table := v_parent_prefix || '_' || p_queue_name;
        v_default_table := v_parent_table || '_d';

        select exists (
          select 1
          from pg_inherits inh
          join pg_class parent on parent.oid = inh.inhparent
          join pg_class child on child.oid = inh.inhrelid
          join pg_namespace n on n.oid = parent.relnamespace
          where n.nspname = 'absurd'
            and parent.relname = v_parent_table
            and child.relname = v_default_table
        )
        into v_default_attached;

        if not coalesce(v_default_attached, false) then
          continue;
        end if;

        -- Block out-of-window writes into the default partition while we
        -- validate emptiness and detach/drop it.
        execute format(
          'lock table absurd.%I in access exclusive mode',
          v_default_table
        );

        execute format(
          'select exists (select 1 from absurd.%I limit 1)',
          v_default_table
        )
        into v_default_has_rows;

        if coalesce(v_default_has_rows, false) then
          raise exception
            'Cannot disable default_partition for queue "%": default partition "%" is not empty',
            p_queue_name,
            v_default_table;
        end if;

        execute format(
          'alter table absurd.%I detach partition absurd.%I',
          v_parent_table,
          v_default_table
        );
        execute format('drop table if exists absurd.%I', v_default_table);
      end loop;
    end if;
  end if;
end;
$$;

-- Returns the current state and terminal payload (if any) for a task.
--
-- Non-terminal states (pending/running/sleeping) return result/failure_reason
-- as NULL. Completed tasks expose completed_payload as result. Failed tasks
-- expose the last run failure_reason.
create function absurd.get_task_result (
  p_queue_name text,
  p_task_id uuid
)
  returns table (
    task_id uuid,
    state text,
    result jsonb,
    failure_reason jsonb
  )
  language plpgsql
as $$
begin
  p_queue_name := absurd.validate_queue_name(p_queue_name);

  return query execute format(
    'select t.task_id,
            t.state,
            case when t.state = ''completed'' then t.completed_payload else null end as result,
            case when t.state = ''failed'' then r.failure_reason else null end as failure_reason
       from absurd.%I t
       left join absurd.%I r on r.run_id = t.last_attempt_run
      where t.task_id = $1',
    't_' || p_queue_name,
    'r_' || p_queue_name
  ) using p_task_id;
end;
$$;

-- Spawns a given task in a queue.
--
-- If an idempotency_key is provided in p_options, the function will check if a task
-- with that key already exists. If so, it returns the existing task_id with run_id
-- and attempt set to NULL to signal "already exists". This is race-safe via
-- INSERT ... ON CONFLICT DO NOTHING.
create function absurd.spawn_task (
  p_queue_name text,
  p_task_name text,
  p_params jsonb,
  p_options jsonb default '{}'::jsonb
)
  returns table (
    task_id uuid,
    run_id uuid,
    attempt integer,
    created boolean
  )
  language plpgsql
as $$
declare
  v_task_id uuid := absurd.portable_uuidv7();
  v_run_id uuid := absurd.portable_uuidv7();
  v_attempt integer := 1;
  v_headers jsonb;
  v_retry_strategy jsonb;
  v_max_attempts integer;
  v_cancellation jsonb;
  v_idempotency_key text;
  v_existing_task_id uuid;
  v_existing_run_id uuid;
  v_existing_attempt integer;
  v_row_count integer;
  v_storage_mode text := 'unpartitioned';
  v_task_inserted boolean := false;
  v_now timestamptz := absurd.current_time();
  v_params jsonb := coalesce(p_params, 'null'::jsonb);
begin
  if p_task_name is null or length(trim(p_task_name)) = 0 then
    raise exception 'task_name must be provided';
  end if;

  if p_options is not null then
    v_headers := p_options->'headers';
    v_retry_strategy := p_options->'retry_strategy';
    if p_options ? 'max_attempts' then
      v_max_attempts := (p_options->>'max_attempts')::int;
      if v_max_attempts is not null and v_max_attempts < 1 then
        raise exception 'max_attempts must be >= 1';
      end if;
    end if;
    v_cancellation := p_options->'cancellation';
    v_idempotency_key := p_options->>'idempotency_key';
  end if;

  if v_idempotency_key is not null then
    select storage_mode into v_storage_mode
    from absurd.queues
    where queue_name = p_queue_name;

    v_storage_mode := coalesce(v_storage_mode, 'unpartitioned');
    if v_storage_mode not in ('unpartitioned', 'partitioned') then
      raise exception 'Unsupported queue storage mode "%"', v_storage_mode;
    end if;

    if v_storage_mode = 'partitioned' then
      -- Reserve idempotency key via dedicated side table.
      execute format(
        'insert into absurd.%I (idempotency_key, task_id)
         values ($1, $2)
         on conflict (idempotency_key) do nothing',
        'i_' || p_queue_name
      )
      using v_idempotency_key, v_task_id;

      get diagnostics v_row_count = row_count;

      if v_row_count = 0 then
        execute format(
          'select i.task_id, t.last_attempt_run, t.attempts
             from absurd.%I i
             join absurd.%I t on t.task_id = i.task_id
            where i.idempotency_key = $1
              for key share of i',
          'i_' || p_queue_name,
          't_' || p_queue_name
        )
        into v_existing_task_id, v_existing_run_id, v_existing_attempt
        using v_idempotency_key;

        if v_existing_task_id is null then
          raise exception 'Idempotency key "%" in queue "%" was concurrently cleaned up', v_idempotency_key, p_queue_name
            using errcode = '40001',
                  hint = 'Retry spawn_task with the same idempotency key.';
        end if;

        if v_existing_run_id is null then
          raise exception 'Idempotency key "%" in queue "%" resolved to task "%" without a run', v_idempotency_key, p_queue_name, v_existing_task_id;
        end if;

        return query select v_existing_task_id, v_existing_run_id, v_existing_attempt, false;
        return;
      end if;
    else
      -- Unpartitioned queues keep the original unique(idempotency_key)
      -- behavior directly on t_<queue>.
      execute format(
        'insert into absurd.%I (task_id, task_name, params, headers, retry_strategy, max_attempts, cancellation, enqueue_at, first_started_at, state, attempts, last_attempt_run, completed_payload, cancelled_at, idempotency_key)
         values ($1, $2, $3, $4, $5, $6, $7, $8, null, ''pending'', $9, $10, null, null, $11)
         on conflict (idempotency_key) do nothing',
        't_' || p_queue_name
      )
      using v_task_id, p_task_name, v_params, v_headers, v_retry_strategy, v_max_attempts, v_cancellation, v_now, v_attempt, v_run_id, v_idempotency_key;

      get diagnostics v_row_count = row_count;

      if v_row_count = 0 then
        execute format(
          'select task_id, last_attempt_run, attempts
             from absurd.%I
            where idempotency_key = $1',
          't_' || p_queue_name
        )
        into v_existing_task_id, v_existing_run_id, v_existing_attempt
        using v_idempotency_key;

        return query select v_existing_task_id, v_existing_run_id, v_existing_attempt, false;
        return;
      end if;

      v_task_inserted := true;
    end if;
  end if;

  if not v_task_inserted then
    execute format(
      'insert into absurd.%I (task_id, task_name, params, headers, retry_strategy, max_attempts, cancellation, enqueue_at, first_started_at, state, attempts, last_attempt_run, completed_payload, cancelled_at, idempotency_key)
       values ($1, $2, $3, $4, $5, $6, $7, $8, null, ''pending'', $9, $10, null, null, $11)',
      't_' || p_queue_name
    )
    using v_task_id, p_task_name, v_params, v_headers, v_retry_strategy, v_max_attempts, v_cancellation, v_now, v_attempt, v_run_id, v_idempotency_key;
  end if;

  execute format(
    'insert into absurd.%I (run_id, task_id, attempt, state, available_at, wake_event, event_payload, result, failure_reason)
     values ($1, $2, $3, ''pending'', $4, null, null, null, null)',
    'r_' || p_queue_name
  )
  using v_run_id, v_task_id, v_attempt, v_now;

  return query select v_task_id, v_run_id, v_attempt, true;
end;
$$;

-- Workers call this to reserve a task from a given queue
-- for a given reservation period in seconds.
create function absurd.claim_task (
  p_queue_name text,
  p_worker_id text,
  p_claim_timeout integer default 30,
  p_qty integer default 1
)
  returns table (
    run_id uuid,
    task_id uuid,
    attempt integer,
    task_name text,
    params jsonb,
    retry_strategy jsonb,
    max_attempts integer,
    headers jsonb,
    wake_event text,
    event_payload jsonb
  )
  language plpgsql
as $$
declare
  v_now timestamptz := absurd.current_time();
  v_claim_timeout integer := greatest(coalesce(p_claim_timeout, 30), 0);
  v_worker_id text := coalesce(nullif(p_worker_id, ''), 'worker');
  v_qty integer := greatest(coalesce(p_qty, 1), 1);
  v_claim_until timestamptz := null;
  v_sql text;
  v_expired_run record;
  v_cancel_candidate record;
  v_expired_sweep_limit integer;
begin
  if v_claim_timeout > 0 then
    v_claim_until := v_now + make_interval(secs => v_claim_timeout);
  end if;

  -- Keep claim polling work bounded: process at most v_qty expired leases
  -- per claim call.
  v_expired_sweep_limit := greatest(v_qty, 1);

  -- Apply cancellation rules before claiming.
  --
  -- Use cancel_task() so lock order stays consistent (runs first, task second)
  -- with complete_run()/fail_run().
  for v_cancel_candidate in
    execute format(
      'select task_id
         from absurd.%I
        where state in (''pending'', ''sleeping'', ''running'')
          and (
            (
              (cancellation->>''max_delay'')::bigint is not null
              and first_started_at is null
              and extract(epoch from ($1 - enqueue_at)) >= (cancellation->>''max_delay'')::bigint
            )
            or
            (
              (cancellation->>''max_duration'')::bigint is not null
              and first_started_at is not null
              and extract(epoch from ($1 - first_started_at)) >= (cancellation->>''max_duration'')::bigint
            )
          )
        order by task_id',
      't_' || p_queue_name
    )
  using v_now
  loop
    perform absurd.cancel_task(p_queue_name, v_cancel_candidate.task_id);
  end loop;

  for v_expired_run in
    execute format(
      'select run_id,
              claimed_by,
              claim_expires_at,
              attempt
         from absurd.%I
        where state = ''running''
          and claim_expires_at is not null
          and claim_expires_at <= $1
        order by claim_expires_at, run_id
        limit $2
        for update skip locked',
      'r_' || p_queue_name
    )
  using v_now, v_expired_sweep_limit
  loop
    perform absurd.fail_run(
      p_queue_name,
      v_expired_run.run_id,
      jsonb_strip_nulls(jsonb_build_object(
        'name', '$ClaimTimeout',
        'message', 'worker did not finish task within claim interval',
        'workerId', v_expired_run.claimed_by,
        'claimExpiredAt', v_expired_run.claim_expires_at,
        'attempt', v_expired_run.attempt
      )),
      null
    );
  end loop;

  v_sql := format(
    'with candidate as (
        select r.run_id
          from absurd.%1$I r
          join absurd.%2$I t on t.task_id = r.task_id
         where r.state in (''pending'', ''sleeping'')
           and t.state in (''pending'', ''sleeping'', ''running'')
           and r.available_at <= $1
         order by r.available_at, r.run_id
         limit $2
         for update skip locked
     ),
     updated as (
        update absurd.%1$I r
           set state = ''running'',
               claimed_by = $3,
               claim_expires_at = $4,
               started_at = $1,
               available_at = $1
         where run_id in (select run_id from candidate)
         returning r.run_id, r.task_id, r.attempt
     ),
     task_upd as (
        update absurd.%2$I t
           set state = ''running'',
               attempts = greatest(t.attempts, u.attempt),
               first_started_at = coalesce(t.first_started_at, $1),
               last_attempt_run = u.run_id
          from updated u
         where t.task_id = u.task_id
         returning t.task_id
     ),
     wait_cleanup as (
        delete from absurd.%3$I w
         using updated u
        where w.run_id = u.run_id
          and w.timeout_at is not null
          and w.timeout_at <= $1
        returning w.run_id
     )
     select
       u.run_id,
       u.task_id,
       u.attempt,
       t.task_name,
       t.params,
       t.retry_strategy,
       t.max_attempts,
      t.headers,
      r.wake_event,
      r.event_payload
     from updated u
     join absurd.%1$I r on r.run_id = u.run_id
     join absurd.%2$I t on t.task_id = u.task_id
     order by r.available_at, u.run_id',
    'r_' || p_queue_name,
    't_' || p_queue_name,
    'w_' || p_queue_name
  );

  return query execute v_sql using v_now, v_qty, v_worker_id, v_claim_until;
end;
$$;

-- Markes a run as completed
create function absurd.complete_run (
  p_queue_name text,
  p_run_id uuid,
  p_state jsonb default null
)
  returns void
  language plpgsql
as $$
declare
  v_task_id uuid;
  v_state text;
  v_now timestamptz := absurd.current_time();
begin
  execute format(
    'select task_id, state
       from absurd.%I
      where run_id = $1
      for update',
    'r_' || p_queue_name
  )
  into v_task_id, v_state
  using p_run_id;

  if v_task_id is null then
    raise exception 'Run "%" not found in queue "%"', p_run_id, p_queue_name;
  end if;

  if v_state <> 'running' then
    if v_state = 'cancelled' then
      raise exception sqlstate 'AB001' using message = 'Task has been cancelled';
    end if;
    if v_state = 'failed' then
      raise exception sqlstate 'AB002' using message = format('Run "%s" has already failed in queue "%s"', p_run_id, p_queue_name);
    end if;
    raise exception 'Run "%" is not currently running in queue "%"', p_run_id, p_queue_name;
  end if;

  execute format(
    'update absurd.%I
        set state = ''completed'',
            completed_at = $2,
            result = $3
      where run_id = $1',
    'r_' || p_queue_name
  ) using p_run_id, v_now, p_state;

  execute format(
    'update absurd.%I
        set state = ''completed'',
            completed_payload = $2,
            last_attempt_run = $3
      where task_id = $1',
    't_' || p_queue_name
  ) using v_task_id, p_state, p_run_id;

  execute format(
    'delete from absurd.%I where run_id = $1',
    'w_' || p_queue_name
  ) using p_run_id;
end;
$$;

create function absurd.schedule_run (
  p_queue_name text,
  p_run_id uuid,
  p_wake_at timestamptz
)
  returns void
  language plpgsql
as $$
declare
  v_task_id uuid;
begin
  execute format(
    'select task_id
       from absurd.%I
      where run_id = $1
        and state = ''running''
      for update',
    'r_' || p_queue_name
  )
  into v_task_id
  using p_run_id;

  if v_task_id is null then
    raise exception 'Run "%" is not currently running in queue "%"', p_run_id, p_queue_name;
  end if;

  execute format(
    'update absurd.%I
        set state = ''sleeping'',
            claimed_by = null,
            claim_expires_at = null,
            available_at = $2,
            wake_event = null
      where run_id = $1',
    'r_' || p_queue_name
  ) using p_run_id, p_wake_at;

  execute format(
    'update absurd.%I
        set state = ''sleeping''
      where task_id = $1',
    't_' || p_queue_name
  ) using v_task_id;
end;
$$;

create function absurd.fail_run (
  p_queue_name text,
  p_run_id uuid,
  p_reason jsonb,
  p_retry_at timestamptz default null
)
  returns void
  language plpgsql
as $$
declare
  v_task_id uuid;
  v_attempt integer;
  v_run_state text;
  v_retry_strategy jsonb;
  v_max_attempts integer;
  v_now timestamptz := absurd.current_time();
  v_next_attempt integer;
  v_delay_seconds double precision := 0;
  v_next_available timestamptz;
  v_retry_kind text;
  v_base double precision;
  v_factor double precision;
  v_max_seconds double precision;
  v_first_started timestamptz;
  v_cancellation jsonb;
  v_max_duration bigint;
  v_task_cancel boolean := false;
  v_new_run_id uuid;
  v_task_state_after text;
  v_recorded_attempt integer;
  v_last_attempt_run uuid := p_run_id;
  v_cancelled_at timestamptz := null;
begin
  execute format(
    'select r.task_id, r.attempt, r.state
       from absurd.%I r
      where r.run_id = $1
      for update',
    'r_' || p_queue_name
  )
  into v_task_id, v_attempt, v_run_state
  using p_run_id;

  if v_task_id is null then
    raise exception 'Run "%" cannot be failed in queue "%"', p_run_id, p_queue_name;
  end if;

  if v_run_state = 'cancelled' then
    raise exception sqlstate 'AB001' using message = 'Task has been cancelled';
  end if;

  if v_run_state = 'failed' then
    raise exception sqlstate 'AB002' using message = format('Run "%s" has already failed in queue "%s"', p_run_id, p_queue_name);
  end if;

  if v_run_state not in ('running', 'sleeping') then
    raise exception 'Run "%" cannot be failed in queue "%"', p_run_id, p_queue_name;
  end if;

  execute format(
    'select retry_strategy, max_attempts, first_started_at, cancellation
       from absurd.%I
      where task_id = $1
      for update',
    't_' || p_queue_name
  )
  into v_retry_strategy, v_max_attempts, v_first_started, v_cancellation
  using v_task_id;

  execute format(
    'update absurd.%I
        set state = ''failed'',
            wake_event = null,
            failed_at = $2,
            failure_reason = $3
      where run_id = $1',
    'r_' || p_queue_name
  ) using p_run_id, v_now, p_reason;

  v_next_attempt := v_attempt + 1;
  v_task_state_after := 'failed';
  v_recorded_attempt := v_attempt;

  if v_max_attempts is null or v_next_attempt <= v_max_attempts then
    if p_retry_at is not null then
      v_next_available := p_retry_at;
    else
      v_retry_kind := coalesce(v_retry_strategy->>'kind', 'none');
      if v_retry_kind = 'fixed' then
        v_base := coalesce((v_retry_strategy->>'base_seconds')::double precision, 60);
        v_delay_seconds := v_base;
      elsif v_retry_kind = 'exponential' then
        v_base := coalesce((v_retry_strategy->>'base_seconds')::double precision, 30);
        v_factor := coalesce((v_retry_strategy->>'factor')::double precision, 2);
        v_delay_seconds := v_base * power(v_factor, greatest(v_attempt - 1, 0));
        v_max_seconds := (v_retry_strategy->>'max_seconds')::double precision;
        if v_max_seconds is not null then
          v_delay_seconds := least(v_delay_seconds, v_max_seconds);
        end if;
      else
        v_delay_seconds := 0;
      end if;
      v_next_available := v_now + (v_delay_seconds * interval '1 second');
    end if;

    if v_next_available < v_now then
      v_next_available := v_now;
    end if;

    if v_cancellation is not null then
      v_max_duration := (v_cancellation->>'max_duration')::bigint;
      if v_max_duration is not null and v_first_started is not null then
        if extract(epoch from (v_next_available - v_first_started)) >= v_max_duration then
          v_task_cancel := true;
        end if;
      end if;
    end if;

    if not v_task_cancel then
      v_task_state_after := case when v_next_available > v_now then 'sleeping' else 'pending' end;
      v_new_run_id := absurd.portable_uuidv7();
      v_recorded_attempt := v_next_attempt;
      v_last_attempt_run := v_new_run_id;
      execute format(
        'insert into absurd.%I (run_id, task_id, attempt, state, available_at, wake_event, event_payload, result, failure_reason)
         values ($1, $2, $3, $4, $5, null, null, null, null)',
        'r_' || p_queue_name
      )
      using v_new_run_id, v_task_id, v_next_attempt, v_task_state_after, v_next_available;
    end if;
  end if;

  if v_task_cancel then
    v_task_state_after := 'cancelled';
    v_cancelled_at := v_now;
    v_recorded_attempt := greatest(v_recorded_attempt, v_attempt);
    v_last_attempt_run := p_run_id;
  end if;

  execute format(
    'update absurd.%I
        set state = $2,
            attempts = greatest(attempts, $3),
            last_attempt_run = $4,
            cancelled_at = coalesce(cancelled_at, $5)
      where task_id = $1',
    't_' || p_queue_name
  ) using v_task_id, v_task_state_after, v_recorded_attempt, v_last_attempt_run, v_cancelled_at;

  execute format(
    'delete from absurd.%I where run_id = $1',
    'w_' || p_queue_name
  ) using p_run_id;
end;
$$;

-- Retries a failed task either by extending attempts on the same task or by
-- spawning a brand new task from the original inputs.
--
-- Options:
-- - spawn_new (boolean, default false): create a new task instead of retrying in-place.
-- - max_attempts (integer, optional): for in-place retry, defaults to
--   coalesce(current max_attempts, current attempts) + 1 and must be greater
--   than current attempts; for spawn_new it overrides copied max_attempts on
--   the new task.
create function absurd.retry_task (
  p_queue_name text,
  p_task_id uuid,
  p_options jsonb default '{}'::jsonb
)
  returns table (
    task_id uuid,
    run_id uuid,
    attempt integer,
    created boolean
  )
  language plpgsql
as $$
declare
  v_now timestamptz := absurd.current_time();
  v_spawn_new boolean := false;
  v_requested_max_attempts integer;

  v_task_name text;
  v_params jsonb;
  v_headers jsonb;
  v_retry_strategy jsonb;
  v_task_max_attempts integer;
  v_cancellation jsonb;
  v_task_attempts integer;
  v_task_state text;

  v_new_run_id uuid;
  v_new_attempt integer;
  v_spawn_options jsonb;
begin
  if p_options is not null then
    if p_options ? 'spawn_new' then
      v_spawn_new := coalesce((p_options->>'spawn_new')::boolean, false);
    end if;
    if p_options ? 'max_attempts' then
      v_requested_max_attempts := (p_options->>'max_attempts')::int;
      if v_requested_max_attempts is not null and v_requested_max_attempts < 1 then
        raise exception 'max_attempts must be >= 1';
      end if;
    end if;
  end if;

  execute format(
    'select task_name,
            params,
            headers,
            retry_strategy,
            max_attempts,
            cancellation,
            attempts,
            state
       from absurd.%I
      where task_id = $1
      for update',
    't_' || p_queue_name
  )
  into v_task_name,
       v_params,
       v_headers,
       v_retry_strategy,
       v_task_max_attempts,
       v_cancellation,
       v_task_attempts,
       v_task_state
  using p_task_id;

  if v_task_state is null then
    raise exception 'Task "%" not found in queue "%"', p_task_id, p_queue_name;
  end if;

  if v_task_state <> 'failed' then
    raise exception 'Task "%" is not currently failed in queue "%"', p_task_id, p_queue_name;
  end if;

  if v_spawn_new then
    v_spawn_options := jsonb_strip_nulls(jsonb_build_object(
      'headers', v_headers,
      'retry_strategy', v_retry_strategy,
      'max_attempts', coalesce(v_requested_max_attempts, v_task_max_attempts),
      'cancellation', v_cancellation
    ));

    return query
      select s.task_id, s.run_id, s.attempt, s.created
        from absurd.spawn_task(p_queue_name, v_task_name, v_params, v_spawn_options) s;
    return;
  end if;

  if v_requested_max_attempts is null then
    v_requested_max_attempts := coalesce(v_task_max_attempts, v_task_attempts) + 1;
  end if;

  if v_requested_max_attempts <= v_task_attempts then
    raise exception 'max_attempts (%) must be greater than current attempts (%)',
      v_requested_max_attempts,
      v_task_attempts;
  end if;

  v_new_run_id := absurd.portable_uuidv7();
  v_new_attempt := v_task_attempts + 1;

  execute format(
    'insert into absurd.%I (run_id, task_id, attempt, state, available_at, wake_event, event_payload, result, failure_reason)
     values ($1, $2, $3, ''pending'', $4, null, null, null, null)',
    'r_' || p_queue_name
  )
  using v_new_run_id, p_task_id, v_new_attempt, v_now;

  execute format(
    'update absurd.%I
        set state = ''pending'',
            attempts = greatest(attempts, $2),
            max_attempts = $3,
            last_attempt_run = $4,
            cancelled_at = null
      where task_id = $1',
    't_' || p_queue_name
  )
  using p_task_id, v_new_attempt, v_requested_max_attempts, v_new_run_id;

  return query select p_task_id, v_new_run_id, v_new_attempt, false;
end;
$$;

create function absurd.set_task_checkpoint_state (
  p_queue_name text,
  p_task_id uuid,
  p_step_name text,
  p_state jsonb,
  p_owner_run uuid,
  p_extend_claim_by integer default null
)
  returns void
  language plpgsql
as $$
declare
  v_now timestamptz := absurd.current_time();
  v_new_attempt integer;
  v_existing_attempt integer;
  v_existing_owner uuid;
  v_task_state text;
  v_run_state text;
begin
  if p_step_name is null or length(trim(p_step_name)) = 0 then
    raise exception 'step_name must be provided';
  end if;

  execute format(
    'select r.attempt, r.state, t.state
       from absurd.%I r
       join absurd.%I t on t.task_id = r.task_id
      where r.run_id = $1',
    'r_' || p_queue_name,
    't_' || p_queue_name
  )
  into v_new_attempt, v_run_state, v_task_state
  using p_owner_run;

  if v_new_attempt is null then
    raise exception 'Run "%" not found for checkpoint', p_owner_run;
  end if;

  if v_task_state = 'cancelled' then
    raise exception sqlstate 'AB001' using message = 'Task has been cancelled';
  end if;

  if v_run_state = 'failed' then
    raise exception sqlstate 'AB002' using message = format('Run "%s" has already failed in queue "%s"', p_owner_run, p_queue_name);
  end if;

  -- Extend the claim if requested
  if p_extend_claim_by is not null and p_extend_claim_by > 0 then
    execute format(
      'update absurd.%I
          set claim_expires_at = $2 + make_interval(secs => $3)
        where run_id = $1
          and state = ''running''
          and claim_expires_at is not null',
      'r_' || p_queue_name
    )
    using p_owner_run, v_now, p_extend_claim_by;
  end if;

  execute format(
    'select c.owner_run_id,
            r.attempt
       from absurd.%I c
       left join absurd.%I r on r.run_id = c.owner_run_id
      where c.task_id = $1
        and c.checkpoint_name = $2',
    'c_' || p_queue_name,
    'r_' || p_queue_name
  )
  into v_existing_owner, v_existing_attempt
  using p_task_id, p_step_name;

  if v_existing_owner is null or v_existing_attempt is null or v_new_attempt >= v_existing_attempt then
    execute format(
      'insert into absurd.%I (task_id, checkpoint_name, state, status, owner_run_id, updated_at)
       values ($1, $2, $3, ''committed'', $4, $5)
       on conflict (task_id, checkpoint_name)
       do update set state = excluded.state,
                     status = excluded.status,
                     owner_run_id = excluded.owner_run_id,
                     updated_at = excluded.updated_at',
      'c_' || p_queue_name
    ) using p_task_id, p_step_name, p_state, p_owner_run, v_now;
  end if;
end;
$$;

create function absurd.extend_claim (
  p_queue_name text,
  p_run_id uuid,
  p_extend_by integer
)
  returns void
  language plpgsql
as $$
declare
  v_now timestamptz := absurd.current_time();
  v_task_state text;
  v_run_state text;
  v_claim_expires_at timestamptz;
begin
  if p_extend_by is null or p_extend_by <= 0 then
    raise exception 'extend_by must be > 0';
  end if;

  execute format(
    'select r.state,
            r.claim_expires_at,
            t.state
       from absurd.%I r
       join absurd.%I t on t.task_id = r.task_id
      where r.run_id = $1
      for update',
    'r_' || p_queue_name,
    't_' || p_queue_name
  )
  into v_run_state, v_claim_expires_at, v_task_state
  using p_run_id;

  if v_run_state is null then
    raise exception 'Run "%" not found in queue "%"', p_run_id, p_queue_name;
  end if;

  if v_task_state = 'cancelled' then
    raise exception sqlstate 'AB001' using message = 'Task has been cancelled';
  end if;

  if v_run_state <> 'running' then
    if v_run_state = 'failed' then
      raise exception sqlstate 'AB002' using message = format('Run "%s" has already failed in queue "%s"', p_run_id, p_queue_name);
    end if;
    raise exception 'Run "%" is not currently running in queue "%"', p_run_id, p_queue_name;
  end if;

  if v_claim_expires_at is null then
    raise exception 'Run "%" does not have an active claim in queue "%"', p_run_id, p_queue_name;
  end if;

  execute format(
    'update absurd.%I
        set claim_expires_at = $2 + make_interval(secs => $3)
      where run_id = $1',
    'r_' || p_queue_name
  )
  using p_run_id, v_now, p_extend_by;
end;
$$;

-- Returns one checkpoint by name. By default only committed checkpoint rows
-- are visible; pass p_include_pending = true to include pending rows.
create function absurd.get_task_checkpoint_state (
  p_queue_name text,
  p_task_id uuid,
  p_step_name text,
  p_include_pending boolean default false
)
  returns table (
    checkpoint_name text,
    state jsonb,
    status text,
    owner_run_id uuid,
    updated_at timestamptz
  )
  language plpgsql
as $$
begin
  return query execute format(
    'select checkpoint_name, state, status, owner_run_id, updated_at
       from absurd.%I
      where task_id = $1
        and checkpoint_name = $2
        and ($3 or status = ''committed'')',
    'c_' || p_queue_name
  ) using p_task_id, p_step_name, coalesce(p_include_pending, false);
end;
$$;

-- Returns committed checkpoints visible to the given run. The run must belong
-- to the provided task, and checkpoints from later attempts are hidden.
create function absurd.get_task_checkpoint_states (
  p_queue_name text,
  p_task_id uuid,
  p_run_id uuid
)
  returns table (
    checkpoint_name text,
    state jsonb,
    status text,
    owner_run_id uuid,
    updated_at timestamptz
  )
  language plpgsql
as $$
declare
  v_run_task_id uuid;
  v_run_attempt integer;
begin
  execute format(
    'select task_id, attempt
       from absurd.%I
      where run_id = $1',
    'r_' || p_queue_name
  )
  into v_run_task_id, v_run_attempt
  using p_run_id;

  if v_run_task_id is null then
    raise exception 'Run "%" not found in queue "%"', p_run_id, p_queue_name;
  end if;

  if v_run_task_id <> p_task_id then
    raise exception 'Run "%" does not belong to task "%" in queue "%"', p_run_id, p_task_id, p_queue_name;
  end if;

  return query execute format(
    'select c.checkpoint_name,
            c.state,
            c.status,
            c.owner_run_id,
            c.updated_at
       from absurd.%1$I c
       left join absurd.%2$I owner_run on owner_run.run_id = c.owner_run_id
      where c.task_id = $1
        and c.status = ''committed''
        and (owner_run.attempt is null or owner_run.attempt <= $2)
      order by c.updated_at asc',
    'c_' || p_queue_name,
    'r_' || p_queue_name
  ) using p_task_id, v_run_attempt;
end;
$$;

create function absurd.await_event (
  p_queue_name text,
  p_task_id uuid,
  p_run_id uuid,
  p_step_name text,
  p_event_name text,
  p_timeout integer default null
)
  returns table (
    should_suspend boolean,
    payload jsonb
  )
  language plpgsql
as $$
declare
  v_run_state text;
  v_existing_payload jsonb;
  v_event_payload jsonb;
  v_checkpoint_payload jsonb;
  v_resolved_payload jsonb;
  v_timeout_at timestamptz;
  v_available_at timestamptz;
  v_now timestamptz := absurd.current_time();
  v_task_state text;
  v_wake_event text;
begin
  if p_event_name is null or length(trim(p_event_name)) = 0 then
    raise exception 'event_name must be provided';
  end if;

  if p_timeout is not null then
    if p_timeout < 0 then
      raise exception 'timeout must be non-negative';
    end if;
    v_timeout_at := v_now + (p_timeout::double precision * interval '1 second');
  end if;

  v_available_at := coalesce(v_timeout_at, 'infinity'::timestamptz);

  execute format(
    'select state
       from absurd.%I
      where task_id = $1
        and checkpoint_name = $2',
    'c_' || p_queue_name
  )
  into v_checkpoint_payload
  using p_task_id, p_step_name;

  if v_checkpoint_payload is not null then
    return query select false, v_checkpoint_payload;
    return;
  end if;

  -- Ensure a row exists for this event so we can take a row-level lock.
  --
  -- We use payload IS NULL as the sentinel for "not emitted yet".  emit_event
  -- always writes a non-NULL payload (at minimum JSON null).
  --
  -- Lock ordering is important to avoid deadlocks: await_event locks the event
  -- row first (FOR SHARE) and then the run row (FOR UPDATE).  emit_event
  -- naturally locks the event row via its UPSERT before touching waits/runs.
  execute format(
    'insert into absurd.%I (event_name, payload, emitted_at)
     values ($1, null, ''epoch''::timestamptz)
     on conflict (event_name) do nothing',
    'e_' || p_queue_name
  ) using p_event_name;

  execute format(
    'select 1
       from absurd.%I
      where event_name = $1
      for share',
    'e_' || p_queue_name
  ) using p_event_name;

  execute format(
    'select r.state, r.event_payload, r.wake_event, t.state
       from absurd.%I r
       join absurd.%I t on t.task_id = r.task_id
      where r.run_id = $1
      for update',
    'r_' || p_queue_name,
    't_' || p_queue_name
  )
  into v_run_state, v_existing_payload, v_wake_event, v_task_state
  using p_run_id;

  if v_run_state is null then
    raise exception 'Run "%" not found while awaiting event', p_run_id;
  end if;

  if v_task_state = 'cancelled' then
    raise exception sqlstate 'AB001' using message = 'Task has been cancelled';
  end if;

  execute format(
    'select payload
       from absurd.%I
      where event_name = $1',
    'e_' || p_queue_name
  )
  into v_event_payload
  using p_event_name;

  if v_existing_payload is not null then
    execute format(
      'update absurd.%I
          set event_payload = null
        where run_id = $1',
      'r_' || p_queue_name
    ) using p_run_id;

    if v_event_payload is not null and v_event_payload = v_existing_payload then
      v_resolved_payload := v_existing_payload;
    end if;
  end if;

  if v_run_state <> 'running' then
    raise exception 'Run "%" must be running to await events', p_run_id;
  end if;

  if v_resolved_payload is null and v_event_payload is not null then
    v_resolved_payload := v_event_payload;
  end if;

  if v_resolved_payload is not null then
    execute format(
      'insert into absurd.%I (task_id, checkpoint_name, state, status, owner_run_id, updated_at)
       values ($1, $2, $3, ''committed'', $4, $5)
       on conflict (task_id, checkpoint_name)
       do update set state = excluded.state,
                     status = excluded.status,
                     owner_run_id = excluded.owner_run_id,
                     updated_at = excluded.updated_at',
      'c_' || p_queue_name
    ) using p_task_id, p_step_name, v_resolved_payload, p_run_id, v_now;
    return query select false, v_resolved_payload;
    return;
  end if;

  -- Detect if we resumed due to timeout: wake_event matches and payload is null
  if v_resolved_payload is null and v_wake_event = p_event_name and v_existing_payload is null then
    -- Resumed due to timeout; don't re-sleep and don't create a new wait
    execute format(
      'update absurd.%I set wake_event = null where run_id = $1',
      'r_' || p_queue_name
    ) using p_run_id;
    return query select false, null::jsonb;
    return;
  end if;

  execute format(
    'insert into absurd.%I (task_id, run_id, step_name, event_name, timeout_at, created_at)
     values ($1, $2, $3, $4, $5, $6)
     on conflict (run_id, step_name)
     do update set event_name = excluded.event_name,
                   timeout_at = excluded.timeout_at,
                   created_at = excluded.created_at',
    'w_' || p_queue_name
  ) using p_task_id, p_run_id, p_step_name, p_event_name, v_timeout_at, v_now;

  execute format(
    'update absurd.%I
        set state = ''sleeping'',
            claimed_by = null,
            claim_expires_at = null,
            available_at = $3,
            wake_event = $2,
            event_payload = null
      where run_id = $1',
    'r_' || p_queue_name
  ) using p_run_id, p_event_name, v_available_at;

  execute format(
    'update absurd.%I
        set state = ''sleeping''
      where task_id = $1',
    't_' || p_queue_name
  ) using p_task_id;

  return query select true, null::jsonb;
  return;
end;
$$;

create function absurd.emit_event (
  p_queue_name text,
  p_event_name text,
  p_payload jsonb default null
)
  returns void
  language plpgsql
as $$
declare
  v_now timestamptz := absurd.current_time();
  v_payload jsonb := coalesce(p_payload, 'null'::jsonb);
  v_emit_applied integer;
begin
  if p_event_name is null or length(trim(p_event_name)) = 0 then
    raise exception 'event_name must be provided';
  end if;

  -- Events are immutable once emitted: first write wins.
  --
  -- await_event() may pre-create a row with payload=NULL as a "not emitted"
  -- sentinel. We allow exactly one transition NULL -> JSON payload.
  execute format(
    'insert into absurd.%1$I as e (event_name, payload, emitted_at)
     values ($1, $2, $3)
     on conflict (event_name)
     do update set payload = excluded.payload,
                   emitted_at = excluded.emitted_at
      where e.payload is null',
    'e_' || p_queue_name
  ) using p_event_name, v_payload, v_now;

  get diagnostics v_emit_applied = row_count;

  -- Event was already emitted earlier; do not overwrite cached payload or
  -- re-run wakeup side effects.
  if v_emit_applied = 0 then
    return;
  end if;

  execute format(
    'with expired_waits as (
        delete from absurd.%1$I w
         where w.event_name = $1
           and w.timeout_at is not null
           and w.timeout_at <= $2
         returning w.run_id
     ),
     affected as (
        select run_id, task_id, step_name
          from absurd.%1$I
         where event_name = $1
           and (timeout_at is null or timeout_at > $2)
     ),
     updated_runs as (
        update absurd.%2$I r
           set state = ''pending'',
               available_at = $2,
               wake_event = null,
               event_payload = $3,
               claimed_by = null,
               claim_expires_at = null
         where r.run_id in (select run_id from affected)
           and r.state = ''sleeping''
         returning r.run_id, r.task_id
     ),
     checkpoint_upd as (
        insert into absurd.%3$I (task_id, checkpoint_name, state, status, owner_run_id, updated_at)
        select a.task_id, a.step_name, $3, ''committed'', a.run_id, $2
          from affected a
          join updated_runs ur on ur.run_id = a.run_id
        on conflict (task_id, checkpoint_name)
        do update set state = excluded.state,
                      status = excluded.status,
                      owner_run_id = excluded.owner_run_id,
                      updated_at = excluded.updated_at
     ),
     updated_tasks as (
        update absurd.%4$I t
           set state = ''pending''
         where t.task_id in (select task_id from updated_runs)
         returning task_id
     )
     delete from absurd.%5$I w
      where w.event_name = $1
        and w.run_id in (select run_id from updated_runs)',
    'w_' || p_queue_name,
    'r_' || p_queue_name,
    'c_' || p_queue_name,
    't_' || p_queue_name,
    'w_' || p_queue_name
  ) using p_event_name, v_now, v_payload;
end;
$$;

-- Manually cancels a task by its task_id.
-- Sets the task state to 'cancelled' and prevents any future runs.
-- Currently running code will detect cancellation at the next checkpoint or heartbeat.
create function absurd.cancel_task (
  p_queue_name text,
  p_task_id uuid
)
  returns void
  language plpgsql
as $$
declare
  v_now timestamptz := absurd.current_time();
  v_task_state text;
begin
  -- Lock active runs before the task row so cancel_task() uses the same
  -- lock acquisition order as complete_run()/fail_run().
  execute format(
    'select run_id
       from absurd.%I
      where task_id = $1
        and state not in (''completed'', ''failed'', ''cancelled'')
      order by run_id
      for update',
    'r_' || p_queue_name
  ) using p_task_id;

  execute format(
    'select state
       from absurd.%I
      where task_id = $1
      for update',
    't_' || p_queue_name
  )
  into v_task_state
  using p_task_id;

  if v_task_state is null then
    raise exception 'Task "%" not found in queue "%"', p_task_id, p_queue_name;
  end if;

  if v_task_state in ('completed', 'failed', 'cancelled') then
    return;
  end if;

  execute format(
    'update absurd.%I
        set state = ''cancelled'',
            cancelled_at = coalesce(cancelled_at, $2)
      where task_id = $1',
    't_' || p_queue_name
  ) using p_task_id, v_now;

  execute format(
    'update absurd.%I
        set state = ''cancelled'',
            claimed_by = null,
            claim_expires_at = null
      where task_id = $1
        and state not in (''completed'', ''failed'', ''cancelled'')',
    'r_' || p_queue_name
  ) using p_task_id;

  execute format(
    'delete from absurd.%I where task_id = $1',
    'w_' || p_queue_name
  ) using p_task_id;
end;
$$;

-- Runs one cleanup batch for all queues (or one specific queue), using
-- per-queue policy stored in absurd.queues.
create function absurd.cleanup_all_queues (
  p_queue_name text default null
)
  returns table (
    queue_name text,
    tasks_deleted integer,
    events_deleted integer
  )
  language plpgsql
as $$
declare
  v_queue record;
  v_cleanup_ttl_seconds integer;
begin
  if p_queue_name is not null then
    p_queue_name := absurd.validate_queue_name(p_queue_name);

    if not exists (
      select 1
      from absurd.queues q
      where q.queue_name = p_queue_name
    ) then
      raise exception 'Queue "%" does not exist', p_queue_name;
    end if;
  end if;

  for v_queue in
    select
      q.queue_name,
      q.cleanup_ttl,
      q.cleanup_limit
    from absurd.queues q
    where p_queue_name is null or q.queue_name = p_queue_name
    order by q.queue_name
  loop
    v_cleanup_ttl_seconds := greatest(
      floor(extract(epoch from v_queue.cleanup_ttl))::integer,
      0
    );

    queue_name := v_queue.queue_name;
    tasks_deleted := absurd.cleanup_tasks(
      v_queue.queue_name,
      v_cleanup_ttl_seconds,
      v_queue.cleanup_limit
    );
    events_deleted := absurd.cleanup_events(
      v_queue.queue_name,
      v_cleanup_ttl_seconds,
      v_queue.cleanup_limit
    );
    return next;
  end loop;
end;
$$;

-- Cleans up old completed, failed, or cancelled tasks and their related data.
-- Deletes tasks whose terminal timestamp (completed_at, failed_at, or cancelled_at)
-- is older than the specified TTL in seconds.
--
-- Returns the number of tasks deleted.
create function absurd.cleanup_tasks (
  p_queue_name text,
  p_ttl_seconds integer,
  p_limit integer default 1000
)
  returns integer
  language plpgsql
as $$
declare
  v_now timestamptz := absurd.current_time();
  v_cutoff timestamptz;
  v_deleted_count integer;
  v_storage_mode text := 'unpartitioned';
begin
  if p_ttl_seconds is null or p_ttl_seconds < 0 then
    raise exception 'TTL must be a non-negative number of seconds';
  end if;

  v_cutoff := v_now - (p_ttl_seconds * interval '1 second');

  select storage_mode into v_storage_mode
  from absurd.queues
  where queue_name = p_queue_name;

  v_storage_mode := coalesce(v_storage_mode, 'unpartitioned');

  if v_storage_mode = 'partitioned' then
    -- Delete in order: wait registrations, checkpoints, runs, idempotency keys,
    -- then tasks.
    execute format(
      'with eligible_tasks as (
          select t.task_id,
                 case
                   when t.state = ''completed'' then r.completed_at
                   when t.state = ''failed'' then r.failed_at
                   when t.state = ''cancelled'' then t.cancelled_at
                   else null
                 end as terminal_at
            from absurd.%1$I t
            left join absurd.%2$I r on r.run_id = t.last_attempt_run
           where t.state in (''completed'', ''failed'', ''cancelled'')
       ),
       to_delete as (
          select task_id
            from eligible_tasks
           where terminal_at is not null
             and terminal_at < $1
           order by terminal_at
           limit $2
       ),
       del_waits as (
          delete from absurd.%3$I w
           where w.task_id in (select task_id from to_delete)
       ),
       del_checkpoints as (
          delete from absurd.%4$I c
           where c.task_id in (select task_id from to_delete)
       ),
       del_runs as (
          delete from absurd.%2$I r
           where r.task_id in (select task_id from to_delete)
       ),
       del_idempotency as (
          delete from absurd.%5$I i
           where i.task_id in (select task_id from to_delete)
       ),
       del_tasks as (
          delete from absurd.%1$I t
           where t.task_id in (select task_id from to_delete)
           returning 1
       )
       select count(*) from del_tasks',
      't_' || p_queue_name,
      'r_' || p_queue_name,
      'w_' || p_queue_name,
      'c_' || p_queue_name,
      'i_' || p_queue_name
    )
    into v_deleted_count
    using v_cutoff, p_limit;
  else
    -- Unpartitioned queues keep idempotency key ownership on the task row,
    -- so no side-table cleanup is needed.
    execute format(
      'with eligible_tasks as (
          select t.task_id,
                 case
                   when t.state = ''completed'' then r.completed_at
                   when t.state = ''failed'' then r.failed_at
                   when t.state = ''cancelled'' then t.cancelled_at
                   else null
                 end as terminal_at
            from absurd.%1$I t
            left join absurd.%2$I r on r.run_id = t.last_attempt_run
           where t.state in (''completed'', ''failed'', ''cancelled'')
       ),
       to_delete as (
          select task_id
            from eligible_tasks
           where terminal_at is not null
             and terminal_at < $1
           order by terminal_at
           limit $2
       ),
       del_waits as (
          delete from absurd.%3$I w
           where w.task_id in (select task_id from to_delete)
       ),
       del_checkpoints as (
          delete from absurd.%4$I c
           where c.task_id in (select task_id from to_delete)
       ),
       del_runs as (
          delete from absurd.%2$I r
           where r.task_id in (select task_id from to_delete)
       ),
       del_tasks as (
          delete from absurd.%1$I t
           where t.task_id in (select task_id from to_delete)
           returning 1
       )
       select count(*) from del_tasks',
      't_' || p_queue_name,
      'r_' || p_queue_name,
      'w_' || p_queue_name,
      'c_' || p_queue_name
    )
    into v_deleted_count
    using v_cutoff, p_limit;
  end if;

  return v_deleted_count;
end;
$$;

-- Cleans up old emitted events.
-- Deletes events whose emitted_at timestamp is older than the specified TTL in seconds.
--
-- Returns the number of events deleted.
create function absurd.cleanup_events (
  p_queue_name text,
  p_ttl_seconds integer,
  p_limit integer default 1000
)
  returns integer
  language plpgsql
as $$
declare
  v_now timestamptz := absurd.current_time();
  v_cutoff timestamptz;
  v_deleted_count integer;
begin
  if p_ttl_seconds is null or p_ttl_seconds < 0 then
    raise exception 'TTL must be a non-negative number of seconds';
  end if;

  v_cutoff := v_now - (p_ttl_seconds * interval '1 second');

  execute format(
    'with to_delete as (
        select event_name
          from absurd.%I
         where emitted_at < $1
         order by emitted_at
         limit $2
     ),
     del_events as (
        delete from absurd.%I e
         where e.event_name in (select event_name from to_delete)
         returning 1
     )
     select count(*) from del_events',
    'e_' || p_queue_name,
    'e_' || p_queue_name
  )
  into v_deleted_count
  using v_cutoff, p_limit;

  return v_deleted_count;
end;
$$;

-- utility function to generate a uuidv7 even for older postgres versions.
create function absurd.portable_uuidv7 ()
  returns uuid
  language plpgsql
  volatile
as $$
declare
  v_server_num integer := current_setting('server_version_num')::int;
  ts_ms bigint;
  b bytea;
  rnd bytea;
  i int;
begin
  if v_server_num >= 180000 then
    return uuidv7 ();
  end if;
  ts_ms := floor(extract(epoch from absurd.current_time()) * 1000)::bigint;
  rnd := uuid_send(uuid_generate_v4 ());
  b := repeat(E'\\000', 16)::bytea;
  for i in 0..5 loop
    b := set_byte(b, i, ((ts_ms >> ((5 - i) * 8)) & 255)::int);
  end loop;
  for i in 6..15 loop
    b := set_byte(b, i, get_byte(rnd, i));
  end loop;
  b := set_byte(b, 6, ((get_byte(b, 6) & 15) | (7 << 4)));
  b := set_byte(b, 8, ((get_byte(b, 8) & 63) | 128));
  return encode(b, 'hex')::uuid;
end;
$$;

-- Extracts the embedded timestamp from a UUIDv7 value.
-- Returns NULL for non-v7 UUIDs.
create function absurd.uuidv7_timestamp (p_id uuid)
  returns timestamptz
  language sql
  immutable
  strict
as $$
  with bytes as (
    select uuid_send(p_id) as b
  ),
  decoded as (
    select
      (get_byte(b, 6) >> 4) as version,
      ((get_byte(b, 0)::bigint << 40) |
       (get_byte(b, 1)::bigint << 32) |
       (get_byte(b, 2)::bigint << 24) |
       (get_byte(b, 3)::bigint << 16) |
       (get_byte(b, 4)::bigint << 8)  |
        get_byte(b, 5)::bigint) as ts_ms
    from bytes
  )
  select case
           when version = 7 then 'epoch'::timestamptz + (ts_ms * interval '1 millisecond')
           else null
         end
  from decoded;
$$;

-- Returns the lowest UUIDv7 value representable for the given timestamp.
-- This is useful for time-window partition bounds over UUIDv7 keys.
create function absurd.uuidv7_floor (p_ts timestamptz)
  returns uuid
  language plpgsql
  immutable
  strict
as $$
declare
  ts_ms bigint := floor(extract(epoch from p_ts) * 1000)::bigint;
  b bytea;
  i int;
begin
  if ts_ms < 0 or ts_ms > 281474976710655 then
    raise exception 'Timestamp "%" is outside UUIDv7 supported range', p_ts;
  end if;

  b := repeat(E'\\000', 16)::bytea;
  for i in 0..5 loop
    b := set_byte(b, i, ((ts_ms >> ((5 - i) * 8)) & 255)::int);
  end loop;

  -- Set UUIDv7 version and RFC4122 variant; keep all randomness bits at 0.
  b := set_byte(b, 6, (7 << 4));
  b := set_byte(b, 8, 128);

  return encode(b, 'hex')::uuid;
end;
$$;

-- Buckets a timestamp to ISO week start (Monday 00:00) in UTC.
create function absurd.week_bucket_utc (p_ts timestamptz)
  returns timestamptz
  language sql
  immutable
  strict
as $$
  select date_trunc('week', p_ts at time zone 'UTC') at time zone 'UTC';
$$;

-- Returns a compact weekly partition tag in YWW format, where:
-- * Y = last digit of the ISO year in UTC
-- * WW = zero-padded ISO week number in UTC (01..53)
--
-- ISO weeks do not have week 0; days at year boundaries can belong
-- to week 52/53 of the previous ISO year.
--
-- Examples:
-- * 2024-01-01 UTC -> 401
-- * 2021-01-01 UTC -> 053 (ISO week 53 of ISO year 2020)
create function absurd.partition_week_tag (p_ts timestamptz)
  returns text
  language sql
  immutable
  strict
as $$
  with bucket as (
    select absurd.week_bucket_utc(p_ts) at time zone 'UTC' as ts
  )
  select
    ((extract(isoyear from ts)::int % 10)::text) ||
    lpad((extract(week from ts)::int)::text, 2, '0')
  from bucket;
$$;

-- Ensures weekly UUIDv7 partitions exist for partitioned queues.
--
-- Window selection is queue-policy driven:
-- * start = week_bucket_utc(now() - partition_lookback)
-- * end   = week_bucket_utc(now() + partition_lookahead)
create function absurd.ensure_partitions (
  p_queue_name text default null
)
  returns void
  language plpgsql
as $$
declare
  v_now timestamptz := absurd.current_time();
  v_window_start timestamptz;
  v_window_end timestamptz;
  v_week_start timestamptz;
  v_week_end timestamptz;
  v_partition_tag text;
  v_uuid_from uuid;
  v_uuid_to uuid;
  v_queue record;
begin
  if p_queue_name is not null then
    p_queue_name := absurd.validate_queue_name(p_queue_name);

    if not exists (
      select 1
      from absurd.queues q
      where q.queue_name = p_queue_name
    ) then
      raise exception 'Queue "%" does not exist', p_queue_name;
    end if;
  end if;

  for v_queue in
    select
      queue_name,
      default_partition,
      partition_lookahead,
      partition_lookback
    from absurd.queues
    where storage_mode = 'partitioned'
      and (p_queue_name is null or queue_name = p_queue_name)
    order by queue_name
  loop
    v_window_start := absurd.week_bucket_utc(v_now - v_queue.partition_lookback);
    v_window_end := absurd.week_bucket_utc(v_now + v_queue.partition_lookahead);

    if v_queue.default_partition = 'enabled' then
      execute format(
        'create table if not exists absurd.%I partition of absurd.%I default',
        't_' || v_queue.queue_name || '_d',
        't_' || v_queue.queue_name
      );
      execute format(
        'create table if not exists absurd.%I partition of absurd.%I default',
        'r_' || v_queue.queue_name || '_d',
        'r_' || v_queue.queue_name
      );
      execute format(
        'create table if not exists absurd.%I partition of absurd.%I default',
        'c_' || v_queue.queue_name || '_d',
        'c_' || v_queue.queue_name
      );
      execute format(
        'create table if not exists absurd.%I partition of absurd.%I default',
        'w_' || v_queue.queue_name || '_d',
        'w_' || v_queue.queue_name
      );
    end if;

    v_week_start := v_window_start;
    while v_week_start <= v_window_end loop
      v_week_end := v_week_start + interval '7 days';
      v_partition_tag := absurd.partition_week_tag(v_week_start);
      v_uuid_from := absurd.uuidv7_floor(v_week_start);
      v_uuid_to := absurd.uuidv7_floor(v_week_end);

      execute format(
        'create table if not exists absurd.%I partition of absurd.%I
         for values from (%L::uuid) to (%L::uuid)',
        't_' || v_queue.queue_name || '_' || v_partition_tag,
        't_' || v_queue.queue_name,
        v_uuid_from,
        v_uuid_to
      );
      execute format(
        'create table if not exists absurd.%I partition of absurd.%I
         for values from (%L::uuid) to (%L::uuid)',
        'r_' || v_queue.queue_name || '_' || v_partition_tag,
        'r_' || v_queue.queue_name,
        v_uuid_from,
        v_uuid_to
      );
      execute format(
        'create table if not exists absurd.%I partition of absurd.%I
         for values from (%L::uuid) to (%L::uuid)',
        'c_' || v_queue.queue_name || '_' || v_partition_tag,
        'c_' || v_queue.queue_name,
        v_uuid_from,
        v_uuid_to
      );
      execute format(
        'create table if not exists absurd.%I partition of absurd.%I
         for values from (%L::uuid) to (%L::uuid)',
        'w_' || v_queue.queue_name || '_' || v_partition_tag,
        'w_' || v_queue.queue_name,
        v_uuid_from,
        v_uuid_to
      );

      v_week_start := v_week_end;
    end loop;
  end loop;
end;
$$;

-- Lists eligible partition tables for detach/drop planning.
--
-- This does not execute detach directly.
-- Callers should construct SQL locally from parent/partition names.
create function absurd.list_detach_candidates (
  p_queue_name text default null
)
  returns table (
    queue_name text,
    parent_table text,
    partition_table text
  )
  language plpgsql
as $$
declare
  v_now timestamptz := absurd.current_time();
  v_queue record;
  v_parent_prefix text;
  v_parent_table text;
  v_parent_oid oid;
  v_part record;
  v_upper_uuid uuid;
  v_upper_ts timestamptz;
  v_has_rows boolean;
begin
  if p_queue_name is not null then
    p_queue_name := absurd.validate_queue_name(p_queue_name);

    if not exists (
      select 1
      from absurd.queues q
      where q.queue_name = p_queue_name
    ) then
      raise exception 'Queue "%" does not exist', p_queue_name;
    end if;
  end if;

  for v_queue in
    select
      q.queue_name,
      q.detach_mode,
      q.detach_min_age
    from absurd.queues q
    where q.storage_mode = 'partitioned'
      and q.detach_mode = 'empty'
      and (p_queue_name is null or q.queue_name = p_queue_name)
    order by q.queue_name
  loop
    foreach v_parent_prefix in array array['t', 'r', 'c', 'w'] loop
      v_parent_table := v_parent_prefix || '_' || v_queue.queue_name;

      select c.oid
        into v_parent_oid
        from pg_class c
        join pg_namespace n on n.oid = c.relnamespace
       where n.nspname = 'absurd'
         and c.relname = v_parent_table;

      if v_parent_oid is null then
        continue;
      end if;

      for v_part in
        select
          child.relname as partition_name,
          pg_get_expr(child.relpartbound, child.oid) as part_bound
        from pg_inherits inh
        join pg_class child on child.oid = inh.inhrelid
        where inh.inhparent = v_parent_oid
      loop
        if v_part.part_bound = 'DEFAULT' then
          continue;
        end if;

        select
          (regexp_match(v_part.part_bound, 'TO \(''([^'']+)''(::uuid)?\)'))[1]::uuid
          into v_upper_uuid;

        if v_upper_uuid is null then
          continue;
        end if;

        v_upper_ts := absurd.uuidv7_timestamp(v_upper_uuid);

        if v_upper_ts is null then
          continue;
        end if;

        if v_upper_ts >= (v_now - v_queue.detach_min_age) then
          continue;
        end if;

        execute format(
          'select exists (select 1 from absurd.%I limit 1)',
          v_part.partition_name
        )
        into v_has_rows;

        if coalesce(v_has_rows, false) then
          continue;
        end if;

        queue_name := v_queue.queue_name;
        parent_table := v_parent_table;
        partition_table := v_part.partition_name;
        return next;
      end loop;
    end loop;
  end loop;
end;
$$;

-- Drops a detached partition table if it is no longer attached.
--
-- Returns true when the table was dropped. If p_unschedule_job_name is
-- provided and pg_cron is available, the matching cron job is unscheduled
-- once the partition is gone. The paired detach job (if derivable from
-- p_unschedule_job_name) is unscheduled as soon as the partition is observed
-- detached so DETACH does not keep retrying.
create function absurd.drop_detached_partition (
  p_partition_table text,
  p_unschedule_job_name text default null
)
  returns boolean
  language plpgsql
as $$
declare
  v_partition_table text := nullif(trim(coalesce(p_partition_table, '')), '');
  v_partition_oid oid;
  v_is_attached boolean := false;
  v_detach_job_name text;
begin
  if p_unschedule_job_name like 'absurd_drop_run_%' then
    v_detach_job_name :=
      'absurd_detach_run_' || substr(p_unschedule_job_name, length('absurd_drop_run_') + 1);
  end if;

  if v_partition_table is null then
    raise exception 'partition table must be provided';
  end if;

  select c.oid
    into v_partition_oid
    from pg_class c
    join pg_namespace n on n.oid = c.relnamespace
   where n.nspname = 'absurd'
     and c.relname = v_partition_table;

  if v_partition_oid is null then
    if p_unschedule_job_name is not null and to_regclass('cron.job') is not null then
      perform cron.unschedule(jobid)
        from cron.job
       where jobname in (p_unschedule_job_name, coalesce(v_detach_job_name, ''));
    end if;
    return false;
  end if;

  select exists (
    select 1
    from pg_inherits
    where inhrelid = v_partition_oid
  )
  into v_is_attached;

  if v_is_attached then
    return false;
  end if;

  -- Once detached, stop retrying detach runs immediately. Keep drop
  -- scheduled until the table is actually dropped.
  if v_detach_job_name is not null and to_regclass('cron.job') is not null then
    perform cron.unschedule(jobid)
      from cron.job
     where jobname = v_detach_job_name;
  end if;

  execute format('drop table if exists absurd.%I', v_partition_table);

  if p_unschedule_job_name is not null and to_regclass('cron.job') is not null then
    perform cron.unschedule(jobid)
      from cron.job
     where jobname = p_unschedule_job_name;
  end if;

  return true;
end;
$$;

-- Schedules per-parent one-at-a-time cron jobs for detach/drop.
--
-- For each parent table, only the oldest eligible partition is scheduled and
-- only when there is no active detach/drop job for that parent.
--
-- Detach jobs run the raw DETACH statement. They use CONCURRENTLY when
-- possible; if a parent still has an attached DEFAULT partition, they fall
-- back to non-concurrent DETACH (Postgres limitation).
--
-- Drop jobs poll via absurd.drop_detached_partition(); once a partition is
-- detached, that function unschedules the paired detach job immediately and
-- keeps retrying drop until the table is gone.
create function absurd.schedule_detach_jobs (
  p_queue_name text default null
)
  returns table (
    job_name text,
    job_id bigint,
    queue_name text,
    partition_table text,
    job_kind text
  )
  language plpgsql
as $$
declare
  v_scope text;
  v_candidate record;
  v_parent_key text;
  v_candidate_key text;
  v_detach_job_name text;
  v_drop_job_name text;
  v_detach_command text;
  v_drop_command text;
  v_parent_has_default_partition boolean;
  v_job_id bigint;
begin
  if p_queue_name is not null then
    p_queue_name := absurd.validate_queue_name(p_queue_name);
  end if;

  if to_regclass('cron.job') is null then
    raise exception 'pg_cron is not available (missing cron.job)';
  end if;

  if not exists (
    select 1
    from pg_proc p
    join pg_namespace n on n.oid = p.pronamespace
    where n.nspname = 'cron'
      and p.proname = 'schedule'
  ) then
    raise exception 'pg_cron is not available (missing cron.schedule)';
  end if;

  if not exists (
    select 1
    from pg_proc p
    join pg_namespace n on n.oid = p.pronamespace
    where n.nspname = 'cron'
      and p.proname = 'unschedule'
  ) then
    raise exception 'pg_cron is not available (missing cron.unschedule)';
  end if;

  v_scope := case
    when p_queue_name is null then 'all'
    else substr(md5(p_queue_name), 1, 12)
  end;

  for v_candidate in
    with candidates as (
      select
        c.*,
        absurd.uuidv7_timestamp(
          (regexp_match(
            pg_get_expr(child.relpartbound, child.oid),
            'TO \(''([^'']+)''(::uuid)?\)'
          ))[1]::uuid
        ) as upper_ts
      from absurd.list_detach_candidates(p_queue_name) c
      join pg_class child on child.relname = c.partition_table
      join pg_namespace n on n.oid = child.relnamespace
      where n.nspname = 'absurd'
    ),
    ranked as (
      select
        candidates.*,
        row_number() over (
          partition by candidates.parent_table
          order by candidates.upper_ts asc nulls last, candidates.partition_table asc
        ) as rn
      from candidates
    )
    select
      ranked.queue_name,
      ranked.parent_table,
      ranked.partition_table
    from ranked
    where ranked.rn = 1
    order by ranked.queue_name, ranked.parent_table, ranked.partition_table
  loop
    v_parent_key := substr(md5(v_candidate.parent_table), 1, 8);

    -- Only one active detach pipeline per parent table.
    if exists (
      select 1
      from cron.job
      where jobname like ('absurd_detach_run_%_' || v_parent_key || '_%')
         or jobname like ('absurd_drop_run_%_' || v_parent_key || '_%')
    ) then
      continue;
    end if;

    v_candidate_key := substr(
      md5(v_candidate.parent_table || ':' || v_candidate.partition_table),
      1,
      12
    );

    v_detach_job_name := format(
      'absurd_detach_run_%s_%s_%s',
      v_scope,
      v_parent_key,
      v_candidate_key
    );
    v_drop_job_name := format(
      'absurd_drop_run_%s_%s_%s',
      v_scope,
      v_parent_key,
      v_candidate_key
    );

    if not exists (
      select 1
      from cron.job
      where jobname = v_detach_job_name
         or jobname like ('absurd_detach_run_%_' || v_candidate_key)
    ) then
      select exists (
        select 1
        from pg_class parent
        join pg_namespace pn on pn.oid = parent.relnamespace
        join pg_inherits inh on inh.inhparent = parent.oid
        join pg_class child on child.oid = inh.inhrelid
        where pn.nspname = 'absurd'
          and parent.relname = v_candidate.parent_table
          and pg_get_expr(child.relpartbound, child.oid) = 'DEFAULT'
      )
      into v_parent_has_default_partition;

      v_detach_command := format(
        'alter table absurd.%I detach partition absurd.%I',
        v_candidate.parent_table,
        v_candidate.partition_table
      );

      if not coalesce(v_parent_has_default_partition, false) then
        v_detach_command := v_detach_command || ' concurrently';
      end if;

      execute 'select cron.schedule($1, $2, $3)'
        into v_job_id
        using v_detach_job_name, '* * * * *', v_detach_command;

      job_name := v_detach_job_name;
      job_id := v_job_id;
      queue_name := v_candidate.queue_name;
      partition_table := v_candidate.partition_table;
      job_kind := 'detach';
      return next;
    end if;

    if not exists (
      select 1
      from cron.job
      where jobname = v_drop_job_name
         or jobname like ('absurd_drop_run_%_' || v_candidate_key)
    ) then
      v_drop_command := format(
        'select absurd.drop_detached_partition(%L, %L);',
        v_candidate.partition_table,
        v_drop_job_name
      );

      execute 'select cron.schedule($1, $2, $3)'
        into v_job_id
        using v_drop_job_name, '* * * * *', v_drop_command;

      job_name := v_drop_job_name;
      job_id := v_job_id;
      queue_name := v_candidate.queue_name;
      partition_table := v_candidate.partition_table;
      job_kind := 'drop';
      return next;
    end if;
  end loop;
end;
$$;

-- Configures pg_cron jobs for partition provisioning, cleanup, and detach planning.
--
-- Detach planning schedules per-partition jobs (via absurd.schedule_detach_jobs)
-- that run raw DETACH statements and follow-up drop checks.
--
-- Requires pg_cron to be installed (or compatible cron schema/functions).
create function absurd.enable_cron (
  p_queue_name text default null,
  p_partition_schedule text default '5 * * * *',
  p_cleanup_schedule text default '17 * * * *',
  p_detach_schedule text default '29 * * * *'
)
  returns table (
    job_name text,
    job_id bigint
  )
  language plpgsql
as $$
declare
  v_queue_exists boolean := false;
  v_queue_literal text;
  v_partition_job_name text;
  v_cleanup_job_name text;
  v_detach_plan_job_name text;
  v_partition_command text;
  v_cleanup_command text;
  v_detach_plan_command text;
  v_partitions_job_id bigint;
  v_cleanup_job_id bigint;
  v_detach_plan_job_id bigint;
  v_existing_job_id bigint;
  v_job_suffix text;
begin
  if p_queue_name is not null then
    p_queue_name := absurd.validate_queue_name(p_queue_name);

    select exists (
      select 1
      from absurd.queues
      where queue_name = p_queue_name
    )
    into v_queue_exists;

    if not v_queue_exists then
      raise exception 'Queue "%" does not exist', p_queue_name;
    end if;
  end if;

  if p_partition_schedule is null or length(trim(p_partition_schedule)) = 0 then
    raise exception 'Partition schedule must be provided';
  end if;

  if p_cleanup_schedule is null or length(trim(p_cleanup_schedule)) = 0 then
    raise exception 'Cleanup schedule must be provided';
  end if;

  if p_detach_schedule is null or length(trim(p_detach_schedule)) = 0 then
    raise exception 'Detach schedule must be provided';
  end if;

  if to_regclass('cron.job') is null then
    raise exception 'pg_cron is not available (missing cron.job)';
  end if;

  if not exists (
    select 1
    from pg_proc p
    join pg_namespace n on n.oid = p.pronamespace
    where n.nspname = 'cron'
      and p.proname = 'schedule'
  ) then
    raise exception 'pg_cron is not available (missing cron.schedule)';
  end if;

  if not exists (
    select 1
    from pg_proc p
    join pg_namespace n on n.oid = p.pronamespace
    where n.nspname = 'cron'
      and p.proname = 'unschedule'
  ) then
    raise exception 'pg_cron is not available (missing cron.unschedule)';
  end if;

  v_queue_literal := case
    when p_queue_name is null then 'null::text'
    else quote_literal(p_queue_name)
  end;

  v_partition_command := format(
    'select absurd.ensure_partitions(%s);',
    v_queue_literal
  );

  v_cleanup_command := format(
    'select * from absurd.cleanup_all_queues(%s);',
    v_queue_literal
  );

  v_job_suffix := case
    when p_queue_name is null then 'all'
    else substr(md5(p_queue_name), 1, 12)
  end;

  v_partition_job_name := 'absurd_partitions_' || v_job_suffix;
  v_cleanup_job_name := 'absurd_cleanup_' || v_job_suffix;
  v_detach_plan_job_name := 'absurd_detach_plan_' || v_job_suffix;

  v_detach_plan_command := format(
    'select * from absurd.schedule_detach_jobs(%s);',
    v_queue_literal
  );

  for v_existing_job_id in
    execute 'select jobid from cron.job where jobname = $1'
    using v_partition_job_name
  loop
    execute 'select cron.unschedule($1)' using v_existing_job_id;
  end loop;

  for v_existing_job_id in
    execute 'select jobid from cron.job where jobname = $1'
    using v_cleanup_job_name
  loop
    execute 'select cron.unschedule($1)' using v_existing_job_id;
  end loop;

  for v_existing_job_id in
    execute 'select jobid from cron.job where jobname = $1'
    using v_detach_plan_job_name
  loop
    execute 'select cron.unschedule($1)' using v_existing_job_id;
  end loop;

  execute 'select cron.schedule($1, $2, $3)'
    into v_partitions_job_id
    using v_partition_job_name, p_partition_schedule, v_partition_command;

  execute 'select cron.schedule($1, $2, $3)'
    into v_cleanup_job_id
    using v_cleanup_job_name, p_cleanup_schedule, v_cleanup_command;

  execute 'select cron.schedule($1, $2, $3)'
    into v_detach_plan_job_id
    using v_detach_plan_job_name, p_detach_schedule, v_detach_plan_command;

  job_name := v_partition_job_name;
  job_id := v_partitions_job_id;
  return next;

  job_name := v_cleanup_job_name;
  job_id := v_cleanup_job_id;
  return next;

  job_name := v_detach_plan_job_name;
  job_id := v_detach_plan_job_id;
  return next;
end;
$$;

-- Removes pg_cron jobs previously installed by absurd.enable_cron.
--
-- If p_queue_name is null, this removes the global ('all') maintenance jobs
-- and global-scope detach/drop run jobs.
-- If p_queue_name is provided, this removes jobs for that specific queue scope,
-- including detach/drop run jobs.
create function absurd.disable_cron (
  p_queue_name text default null
)
  returns table (
    job_name text,
    job_id bigint
  )
  language plpgsql
as $$
declare
  v_job_suffix text;
  v_partition_job_name text;
  v_cleanup_job_name text;
  v_detach_plan_job_name text;
  v_detach_run_pattern text;
  v_drop_run_pattern text;
  v_existing_job record;
begin
  if p_queue_name is not null then
    p_queue_name := absurd.validate_queue_name(p_queue_name);
  end if;

  if to_regclass('cron.job') is null then
    raise exception 'pg_cron is not available (missing cron.job)';
  end if;

  if not exists (
    select 1
    from pg_proc p
    join pg_namespace n on n.oid = p.pronamespace
    where n.nspname = 'cron'
      and p.proname = 'unschedule'
  ) then
    raise exception 'pg_cron is not available (missing cron.unschedule)';
  end if;

  v_job_suffix := case
    when p_queue_name is null then 'all'
    else substr(md5(p_queue_name), 1, 12)
  end;

  v_partition_job_name := 'absurd_partitions_' || v_job_suffix;
  v_cleanup_job_name := 'absurd_cleanup_' || v_job_suffix;
  v_detach_plan_job_name := 'absurd_detach_plan_' || v_job_suffix;
  v_detach_run_pattern := 'absurd_detach_run_' || v_job_suffix || '_%';
  v_drop_run_pattern := 'absurd_drop_run_' || v_job_suffix || '_%';

  for v_existing_job in
    execute 'select jobid, jobname
               from cron.job
              where jobname = $1
                 or jobname = $2
                 or jobname = $3
                 or jobname like $4
                 or jobname like $5
              order by jobname, jobid'
    using v_partition_job_name,
          v_cleanup_job_name,
          v_detach_plan_job_name,
          v_detach_run_pattern,
          v_drop_run_pattern
  loop
    execute 'select cron.unschedule($1)' using v_existing_job.jobid;

    job_name := v_existing_job.jobname;
    job_id := v_existing_job.jobid;
    return next;
  end loop;
end;
$$;