Reconcile legacy ContractClock receipt schema

db/migrations/002_reconcile_execution_receipts.sql

@@ -0,0 +1,36 @@
+-- Earlier generated revisions created execution_receipts with `skill_name`
+-- and without the hashes/task metadata now written by ContractClock. Keep the
+-- migration additive so existing receipts survive and fresh databases (whose
+-- 001 migration already has these columns) remain idempotent.
+ALTER TABLE execution_receipts
+    ADD COLUMN IF NOT EXISTS tool_name TEXT,
+    ADD COLUMN IF NOT EXISTS task_id TEXT,
+    ADD COLUMN IF NOT EXISTS input_hash TEXT,
+    ADD COLUMN IF NOT EXISTS result_hash TEXT;
+
+DO $$
+BEGIN
+    IF EXISTS (
+        SELECT 1
+        FROM information_schema.columns
+        WHERE table_schema = current_schema()
+          AND table_name = 'execution_receipts'
+          AND column_name = 'skill_name'
+    ) THEN
+        EXECUTE 'UPDATE execution_receipts
+                 SET tool_name = COALESCE(tool_name, skill_name)';
+    END IF;
+END
+$$;
+
+UPDATE execution_receipts
+SET tool_name = COALESCE(tool_name, 'legacy'),
+    task_id = COALESCE(task_id, ''),
+    input_hash = COALESCE(input_hash, 'legacy'),
+    result_hash = COALESCE(result_hash, 'legacy');
+
+ALTER TABLE execution_receipts
+    ALTER COLUMN tool_name SET NOT NULL,
+    ALTER COLUMN task_id SET NOT NULL,
+    ALTER COLUMN input_hash SET NOT NULL,
+    ALTER COLUMN result_hash SET NOT NULL;