Added Task number

supabase/migrations/20260221123000_improve_task_number_generation.sql

@@ -0,0 +1,51 @@
+-- Improve task_number generation to eliminate race conditions.
+-- Maintain a separate counter table so concurrent inserts can safely bump the
+-- sequence using an atomic upsert. This migration retains the existing
+-- trigger name but replaces its body, and creates the helper table.
+
+-- 1. Create counter table
+CREATE TABLE IF NOT EXISTS task_number_counters (
+    year_month text PRIMARY KEY,
+    counter bigint NOT NULL
+);
+
+-- 2. Initialize counters from existing tasks
+INSERT INTO task_number_counters(year_month, counter)
+SELECT s.prefix, s.cnt
+FROM (
+    SELECT to_char(created_at::timestamp, 'YYYY-MM-') AS prefix,
+           max((substring(task_number FROM 8))::int) AS cnt
+    FROM tasks
+    GROUP BY prefix
+) s
+ON CONFLICT (year_month) DO UPDATE SET counter = EXCLUDED.counter;
+
+-- 3. Replace trigger function with atomic counter logic
+CREATE OR REPLACE FUNCTION tasks_set_task_number()
+RETURNS trigger AS $$
+DECLARE
+    prefix text;
+    seq bigint;
+BEGIN
+    IF NEW.task_number IS NOT NULL THEN
+        RETURN NEW;
+    END IF;
+
+    prefix := to_char(now(), 'YYYY-MM-');
+    INSERT INTO task_number_counters(year_month, counter)
+        VALUES (prefix, 1)
+        ON CONFLICT (year_month)
+        DO UPDATE SET counter = task_number_counters.counter + 1
+        RETURNING counter INTO seq;
+
+    NEW.task_number := prefix || lpad(seq::text, 5, '0');
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+-- 4. Recreate trigger (drop/recreate to ensure correct function is bound)
+DROP TRIGGER IF EXISTS tasks_set_task_number_before_insert ON tasks;
+CREATE TRIGGER tasks_set_task_number_before_insert
+BEFORE INSERT ON tasks
+FOR EACH ROW
+EXECUTE FUNCTION tasks_set_task_number();