Resume was a claim without a path
Zero sessions in the corpus ever resumed. Durability was a product claim with no exercised path — instrument it or stop claiming it.
The corpus contains 1,186 sessions. The number with a resumed flag is zero. Zero finish events. Seven sessions with workspace changes. If session durability and resume were product claims — and they were, implicitly, every time someone said 'sessions survive restarts' — they were claims without an exercised path.
This is the most common lie in infrastructure software, and it's rarely told deliberately. The persistence layer works: events are written to disk, immutable, replayable. The engineers know the data is there. So 'resume works' feels true. But nobody ever walked the path — kill the server mid-session, restart, continue the same session — and watched it happen. The data existing and the path working are different claims.
Why it matters
An untested recovery path is a liability disguised as a feature. When a real failure hits — a deploy restart, a power cut, a killed process — the operator reaches for resume expecting it to work, because the docs imply it does. That's the worst possible moment to discover it doesn't. The 478-turn session that completed cleanly over ten days is proof the machinery can sustain long work. It's not proof anyone can pick it back up.
There's a second-order cost too. Every feature built on top of resume — handoff between operators, pause-and-continue workflows, disaster recovery stories — inherits the untested foundation. You're building a staircase on a step nobody stood on.
What the fix looks like
Make resume a first-class, named, tested event. When a session continues after an interruption, the runtime emits an explicit resumed event carrying the session id — exactly once, at the continuation point. Not inferred from gaps in timestamps. Not reconstructed from logs. Emitted, named, countable.
Then the corpus can count it. The acceptance test is almost insultingly simple: fresh session, zero resumed events; second prompt on the same session id, exactly one resumed event. The control is the fresh path staying unmarked. If the event never fires in production, the dashboard shows zero and someone asks why — which is exactly the conversation the uninstrumented version never had.
The rule is general and worth tattooing somewhere: a claim without an exercised path is a wish. Instrument the path, count the events, or stop making the claim.
Test it the way disasters happen, not the way demos do: kill -9 the server mid-turn, restart, and continue. If the session picks up with its history intact and exactly one resumed event in the log, the path works. Anything less choreographed than that is theater.