As an outgrowth of the Maker research I did a while back, I ran across
https://wiki.travellerrpg.com/Quarter_Hammer_class_Construction_Drone
and the associated other drones.

These made sense. I did a sketch using T5 build rules, and checked the
Baronet's finances for 1107, and had him pick up a Legionary on
payments
https://wiki.travellerrpg.com/Legionary_class_Corvette

The goal was to crank up Carmel's industry by exploiting the various
trojan belts.

The concern was that cranking it up too much would attract the
attention of the MegaCorps and then things would get ugly. He builds
the swarm up in a set of trojans in the outer system, where nobody
hangs out, and keeps the whole thing quiet. There's originally not
much of a long term plan on how to crank the mainworld up without
attracting the ire of MegaCorps, but having the industrial capability
in hand seems worth while and it would be years before the swarm
matured and surely during that time he'd think of something.

So the timeline I'm working with has Legionary purchase in 1107, and a
mature swarm in 1111/1112, with some of the production diverted along
the way to producing a few 10-ton launches for sale to cover the
payments on the Legionary and pay for the work crews

1111 also sees hiring some naval architects, construction of a space
station for them to live and work on, and building a type-A a year,
selling them, and paying off the Legionary by 1114ish

1114 to 1117 see selling a Type-A a year for expenses and banking most
of it.. and by "banking" we're talking about half of it being buying
stocks in planet-side businesses and helping them expand. Figure
pumping about 15Mcr/year into business growth, and avoiding inflation
by selling needed expansion goods from a shell company the Baronet
owns that's actually the Swarm making stuff.

Early 1117 there's a player adventure we're in the middle of running:
A Vargr courier gets word to the pirate clans that the Emperor was
assasinated before word gets to Carmel. A Vargr pirate chieftan
decides to raid the planet - and the Baronet's swarm is way and gone
out system and can't arrive in time. (The players don't even know the
swarm exists.) This adventure is an introduction for the players to
the Assemblage of 1116

After such a dramatic method of finding out the Imperium is in dire
straits, and finding out his fief is vulnerable, the Baronet goes nuts
on making sure this never happens again. He also suspects that his
liege lords are going to want ships, and that the MegaCorps are going
to be either distracted by the madness or wanting to make huge profits
building ships and want to squish his operation if it becomes a
competitor.

In the short term, he build a lot of SDBs in different variations on
the theme, and plays around with various starship designs. He sees his
main priority as making Carmel safe for his people. He doesn't want to
rely on being left out of the loop again, and builds some couriers of
his own, and a few mini-swarms to support them, sort of a mini X-boat
network that he puts at the disposal of the subsector and sector
nobles. He figures if he keeps it low key, nobody will do the math to
add up what the investment was and nobody's going to ask questions
that bring the MegaCorp hammer down on him.

In 1132, the Assemblage sends  scouts as part of the planning for what
eventually becomes the Battle of Ashes.... and this is where the
sanity check is way off the rails.  Industrial capacity and a
"Invasion will never happen again" has about 1,000,000 dtons of
SDBs/monitors/etc stacked up.  This would explain why the Battle of
Ashes does not mention any Vargr hitting Carmel.

Anything glaringly out of sync above? It all seems to hang together
for me, but it feels like there's something I'm missing.
Is the worry about MegaCorps too strong? What's the threshold there
for getting noticed?
Would building starships to go help the rest of the Domain make more sense?