The former world No 1 improved her match record on the hardcourts of the La Costa Hotel and Spa to 21wins and no defeats. It was her ninth win in as many matches against the Frenchwoman.
"I'm somebody who looks forward rather than backwards," the 29-year-old German said. "But it's a nice feeling to know I've never lost here before."
Graf, who has seen limited action due to injuries over the past two years, is concentrating on getting match tough as the season heads towards the US Open and an attempt at her 22nd major title.
"I'm feeling better and better. My game is pretty solid right now and I'm getting used to playing matches," she said.
Graf began her seventh tournament of the year by breaking Halard-Decugis twice in each set of Tuesday's 57-minute rout.
The former teenage prodigy Jennifer Capriati, who won the tournament in 1991 and 1992, saw her latest comeback effort stalled in the first round again.
After being forced to come through qualifying to get into the main draw, Capriati was beaten 5-7, 6-2, 6-2 by Ai Sugiyama of Japan.
"I'm getting closer but it's real disappointing. I thought I was playing well enough to win," Capriati said. "But being out of the spotlight gives me time to come back."
She has now lost six times in the first round in her last 12 tournaments.