In 2007 the IETF published RFC 4838 and gave a name to a problem most of us never have to think about: what does a network do when there is no instant path from A to B? Delay-Tolerant Networking — the architecture Vint Cerf and the interplanetary-internet crowd built so a probe out past Mars could still reach home across a light-delay of minutes — answers by refusing to pretend the gap isn’t there. Kevin Fall’s 2003 SIGCOMM paper, A Delay-Tolerant Network Architecture for Challenged Internets, set the template: store a bundle, forward it when a link opens, and treat latency as physics, not failure. The current Bundle Protocol, RFC 9171 (2022), makes store-and-forward the first principle rather than the fallback.

This month a consumer app ships the same idea as social interface. Pigeon (Google Play, package com.lkm.pigeon) is a messaging app where nothing arrives instantly. Per its own listing, a message travels a real geographic distance before it lands, and the farther apart you are, the longer the trip. The Pigeon carrier takes “a couple of hours plus the distance” and holds two pictures; Bat only flies between 6pm and 6am; Whisper reveals itself word by word over six hours; Bottle is cast to no one and can surface to a compatible stranger within 24 hours, each finder replying exactly once. One traveling message per carrier at a time. Instant messaging trained us to reply before we’d read.

Here is the part a BIM lead should sit with. The gap between model and site has always been store-and-forward, and we keep pretending it’s instant. You export an IFC, the site opens it Thursday, and the wall you moved Monday is still in its old place on the drywaller’s tablet. IFC — standardised as ISO 16739-1:2018 — is the most important language the AEC industry built this century precisely because it is a plain-text bundle you can open in Notepad. Read one line of a STEP file and it decodes cleanly:

#12=IFCWALLSTANDARDCASE('2O2Fr$t4X7Zf8NOew3FLOH',#5,'Wall-Ext-01',$,$,#38,#41,$);

#12 is the instance id; IFCWALLSTANDARDCASE the class; the 22-character string is the GlobalId (a compressed 128-bit UUID); #5 points at the IfcOwnerHistory — the postmark; 'Wall-Ext-01' the name; #38 and #41 the placement and geometry. That #5 reference is the whole argument: every model that reaches the site is a delayed message, and it carries the timestamp of when it was actually sent.

←TODAY: Pigeon (2026) sells deliberate latency as a feature; DTN (RFC 4838 / 9171) has treated it as physics since 2007. →3012: The offices that survived treated the model as mail with a postmark, not a live feed — they always knew the age of the file the trowel was following. Fulcrum: Latency stops being a bug the moment you can read the timestamp on the thing that arrived late.

Atelier: A small practice living with AI copilots and cloud sync is drowning in the illusion of instant — the model always looks current, the way Pigeon refuses to let it. This Monday, set one policy: no IFC lands on site without its export timestamp printed in the sheet corner. It costs nothing and kills the “but the model said” argument at the container door.

Hack: Read the postmark on the file the bricklayer is actually building from. Don’t trust the filename date — trust the ownership history the exporter wrote inside the bundle. IFC stores it as an IfcTimeStamp: a plain integer of seconds since the Unix epoch (1 January 1970), so one line turns it back into a date.

import ifcopenshell, datetime as dt
model = ifcopenshell.open("site_export.ifc")
stamp = model.by_type("IfcOwnerHistory")[0].CreationDate
print(dt.datetime.fromtimestamp(stamp))  # the model's real postmark

PAZ has covered the cost of pretending delivery is instant before — our piece on Font Awesome’s 99% SendGrid reputation vanishing silently into Gmail’s own filter, where 90% of their list sat on Gmail addresses, is the same lesson in a different pipe: no bounce, no error, just a message that never arrived and a sender who assumed it had. Pigeon, to its credit, “makes no promises about outcomes.” Neither does your model export. The difference is whether you check.

My generation learned this the hard way on format, not latency. The buildings that aged badly weren’t the ugly ones — they were the ones nobody could reopen because the proprietary tool went dark. Pigeon is a lovely, closed app; IFC is a boring, open ISO. Pick your stack this quarter with one question: when the vendor disappears, can a 25-year-old still open the file? Print the postmark, keep the format open, and let the wait be the point.

Source: play.google.com