diff --git a/migrations/022_add_done_status.sql b/migrations/022_add_done_status.sql
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+-- Add "done" status and auto-close workflow
+--
+-- Migration: 022_add_done_status
+-- Purpose: Add "done" status for verification period before auto-closing
+-- Related: CF-454
+--
+-- Status lifecycle with done:
+--   - pending: Created, awaiting approval or dependencies
+--   - open: Approved and ready to start
+--   - in_progress: Currently being worked on
+--   - testing: Implementation complete, being tested
+--   - blocked: Stuck waiting for something
+--   - done: Implementation complete, in 7-day verification period
+--   - completed: Verified stable, auto-closed after 7 days
+--
+-- Verification period:
+--   - Tasks marked "done" wait 7 days before auto-closing to "completed"
+--   - If related issues detected during period, task stays "done" (no auto-close)
+--   - Prevents premature closure and catches regressions
+--
+-- Auto-close workflow:
+--   1. Task marked as "done" → auto_close_at = now() + 7 days
+--   2. Cron job checks daily for tasks past auto_close_at
+--   3. Semantic search detects related issues created since task marked "done"
+--   4. If no related issues → auto-close to "completed"
+--   5. If related issues found → notify, keep as "done"
+
+-- Drop existing constraint
+ALTER TABLE tasks DROP CONSTRAINT IF EXISTS tasks_status_check;
+
+-- Add new constraint with done status
+ALTER TABLE tasks ADD CONSTRAINT tasks_status_check
+    CHECK (status IN ('pending', 'open', 'in_progress', 'testing', 'blocked', 'done', 'completed'));
+
+-- Add auto_close_at column for tracking when to auto-close
+ALTER TABLE tasks ADD COLUMN IF NOT EXISTS auto_close_at TIMESTAMP WITH TIME ZONE;
+
+-- Create index for efficient cron job queries
+CREATE INDEX IF NOT EXISTS idx_tasks_auto_close ON tasks(auto_close_at) WHERE auto_close_at IS NOT NULL;
+
+-- Add comment for documentation
+COMMENT ON COLUMN tasks.auto_close_at IS 'Timestamp when task should auto-close from done to completed (7 days after marked done)';