Most general managers with an undefeated team would be tempted to lean back and enjoy the view, but San Francisco 49ers GM John Lynch isn’t wired that way.

San Francisco sits at 4-0, alone atop the NFC West, and has won games with a roster that at times has looked more like a preseason depth chart than a contender’s starting lineup.

Lynch knows that kind of tightrope act doesn’t last forever. So with the November 10 trade deadline about a month away, he’s making it clear the 49ers are listening.

“I think you’re always in active mode,” Lynch told KNBR this week.

That shouldn’t surprise anyone who has followed the Lynch-Kyle Shanahan era.

This front office has a long habit of making midseason moves, and the most memorable one, the 2023 deal for Chase Young, helped carry the 49ers to Super Bowl LVIII.

Lynch leaned on that history, signaling the team won’t sit on its hands if the right deal comes along.

What’s driving the urgency is the injury report, which has become a weekly horror story.

No team in football has lost more player-games to injury through the first four weeks. The 49ers have 16 players on injured reserve and two more on the PUP list, and that tally doesn’t even include Nick Bosa (calf) or Kyle Juszczyk (knee sprain), who are both expected back at some point this month.

Wide receiver has taken a beating. Ricky Pearsall is done for the year after knee surgery, and De’Zhaun Stribling and Demarcus Robinson are sidelined with ankle injuries. Christian Kirk’s eventual return should give Shanahan another weapon, but the room is thin.

The defensive front is the real emergency. Alfred Collins suffered a season-ending torn patellar tendon, and C.J. West’s knee surgery could keep him out until late in the year.

Only four defensive linemen from the original 53-man roster are currently healthy. San Francisco has patched the holes with former practice-squad players and street signings, and they’ve held up better than anyone expected.

The underlying numbers, though, tell a less comforting story: the 49ers rank in the bottom third of the league in both run-defense efficiency and sack rate.

Some reinforcements are coming from within. Mykel Williams, working back from last November’s ACL tear, could make his season debut as early as Sunday against Seattle. Romello Height has already returned.

Lynch sounded genuinely excited about what this roster will look like once healthy, predicting opponents will have their hands full.

But counting on a clean recovery for an entire injury list is wishful thinking, especially for a franchise that has been snakebitten in recent seasons. The smart play is to buy insurance.

Expect San Francisco to target a stout interior lineman who can anchor against the run, plus an edge rusher who can collapse the pocket opposite Bosa.

Washington, off to a 1-3 start, could become a seller, and defensive tackle Daron Payne, entering the final year of his deal, fits the profile.

The 49ers have already shown they can win ugly. Lynch’s job over the next month is making sure they don’t have to.