feat: execute durable client commands through supervisor

internal/client/spool/migrations.go

@@ -16,6 +16,7 @@ type migration struct {
 var migrations = []migration{
 	{version: 1, sql: schemaV1},
 	{version: 2, sql: schemaV2},
+	{version: 3, sql: schemaV3},
 }
 
 func applyMigrations(ctx context.Context, db *sql.DB) error {
@@ -132,3 +133,15 @@ CREATE TABLE command_specs (
   charged_bytes INTEGER NOT NULL CHECK(charged_bytes > 0)
 ) STRICT, WITHOUT ROWID;
 `
+
+// schemaV3 adds a small durable launch barrier to every accepted command. A
+// value of 2 means launch authorization may have crossed the OS boundary; on
+// restart the client must interrupt that command instead of redispatching it.
+// Keeping these fields on commands makes the barrier part of the existing
+// command-owned quota/accounting row and lets terminal cleanup remove it with
+// the command.
+const schemaV3 = `
+ALTER TABLE commands ADD COLUMN launch_phase INTEGER NOT NULL DEFAULT 0 CHECK(launch_phase BETWEEN 0 AND 2);
+ALTER TABLE commands ADD COLUMN launch_context TEXT NOT NULL DEFAULT '';
+ALTER TABLE commands ADD COLUMN launch_pid INTEGER NOT NULL DEFAULT 0 CHECK(launch_pid >= 0);
+`