-- Record which rule a run came from.
--
-- rule_apply_runs stored only counts ("13 matches · 13 transactions"), which is
-- not enough to decide whether to revert: you cannot tell a merchant rename from
-- a 50/50 split of your entire history. The snapshot column already holds the
-- before-state, but nothing said what was applied or why.
--
-- rule_name is denormalised deliberately. A run must stay readable after the
-- rule it came from is edited or deleted -- the history is a record of what
-- happened, not a pointer to what the rule says today.

ALTER TABLE rule_apply_runs
  ADD COLUMN IF NOT EXISTS rule_id   INTEGER,
  ADD COLUMN IF NOT EXISTS rule_name TEXT,
  -- 'all' = bulk run over every enabled rule; 'rule' = one rule by conditions;
  -- 'selection' = one rule against hand-picked transactions (preview → apply).
  ADD COLUMN IF NOT EXISTS source    TEXT;

ALTER TABLE rule_apply_runs DROP CONSTRAINT IF EXISTS rule_apply_runs_source_check;
ALTER TABLE rule_apply_runs ADD CONSTRAINT rule_apply_runs_source_check
  CHECK (source IS NULL OR source IN ('all', 'rule', 'selection'));

-- No FK to rules: deleting a rule must not cascade away the audit trail.
CREATE INDEX IF NOT EXISTS idx_rule_apply_runs_rule
  ON rule_apply_runs (rule_id) WHERE rule_id IS NOT NULL;

-- Existing rows stay NULL. There is no way to recover which rule they ran;
-- the UI shows them as "unknown rule" rather than guessing.