This is a Stargate SG-1 fanfic that describes the development of the titular Stargate system of interstellar portals.
I found its presentation of the show's mysterious advanced technology as analogous to a contemporary software project particularly memorable.
read online several years ago
The linked version at ArchiveOfOurOwn was posted in 2015; earlier versions were freely available on MacIver's webite.
company that built interstellar portals
Most of the story is presented as a found document, a
diary of one of the Ancients who developed the first Stargates.
However, instead of a "company", the engineer is working for a research council.
worked with very thorough, furry aliens from a species that was paranoid about safety
The narrator of the story worked with one other human and only one alien, a Furling named Temit. The description of Furlings in general as well as the actions of Temit in particular are both consistent with the description "very thorough [and] paranoid about safety".
Furling technology has been so thoroughly overdesigned and tested for bugs that you can never find anything wrong with it.
You may remember Temit as multiple aliens because Furlings in general and Temit an particular use the singular they as a pronoun. For a representative sample of Temit's "paranoia about safety", consider their test procedure:
At this point Temit stepped in and informed us in no uncertain terms that when testing this we would be employing the proper Stargate test procedure that they had implemented ... That is, we would be putting the Stargate in orbit of a planet that was currently on the opposite side of the sun, surround the gate with a forcefield, and operate it remotely from a suitably safe distance ...
Several accidents with the portals were described
Many accidents are described; one that I found especially memorable is the final narrated accident, immediately following the description of Temit's test procedure. The description of the accident ends with the punchline
The bad news is that we're going to have to find another planet to use for testing next time.
Earlier accidents are described in less detail.
Fortunately the receiving room wasn't flammable, and the burns were easily treatable.
We thought things were going pretty well. Then the Earth Stargate exploded.
the aliens bristled when they learned that the teleporter designs weren't fully specified
This is not an exact match; the narrator suggests that Temit bristles to express displeasure.
I'm almost certain the way their fur bristled when they did their first reading of the Stargate source code was a bad sign.
The specific phrase "designs weren't fully specified" does not appear, but a running theme of the story is that the portal system ("Stargates") started with a vague idea, was put into production much sooner than desired by the engineers, and was plagued by unintended and unexpected behavior throughout. Consider the selected quotes:
I still have nightmares when I think about how early in the project we risked this. Some of the bugs we found in the system later could have killed us or worse.
Temit asked me what happened if the wormhole was blocked only after it had properly been formed ... I said that I didn't think that was very likely and they gave me a look.
Anyway, I'm mostly not too worried. Most of these scenarios are really hard to hit, and we'll have plenty of time to work out the issues and the quirks of the behaviour in the next version of the software.
They eventually left, but the company carried on.
As noted earlier in this answer, "they" refers to a singular alien in this story.
The council have decided to deploy the gate network anyway, despite our requests that we would really like another six months of field testing.
In response, Temit announced that they intended to return home to the Furling worlds