Devlog · Engine & Netcode

21 Decks: Locking Blackjack's Full Interior Spec

The largest Strider class got its current name and a complete floor-by-floor interior spec in the same stretch — including a geometry conflict that had already survived three previous attempts to fix it.

Locked17–22 July 2026
CategoryEngine & Netcode
Scope21 decks, full interior spec

Blackjack is COGHEIM's largest Strider class, and it took its current name in the same stretch it got its first complete interior spec — 21 decks, from Roof Aerodrome down to Engine Core. Twenty-one decks, twenty-one for blackjack. That one wasn't an accident.

A Conflict That Took Three Tries

One deck — the Council chamber — had a geometry problem that had already come back across three prior passes at roughly the same 1.2–1.3× ratio mismatch each time. The fix, when it finally landed, was almost embarrassingly simple: the hull doesn't need to be square. Deck 10 is just elongated. Three attempts spent trying to force a symmetric solution onto a problem that only needed permission to be asymmetric.

The actual lesson: a spec problem that keeps recurring in slightly different forms is usually not a spec problem. It's an unexamined assumption sitting upstream of the spec — in this case, that the hull had to be square at all.

Small Locks That Add Up

Past the headline geometry fix, this pass closed out a list of smaller open questions that had been sitting unresolved: the stairwell locked as interior-only with jogged positions — deliberately the opposite of the Long Climb's exposed panoramic route, so the two vertical-transit experiences don't compete with each other. Deck 4 locked as the Resource Hub, closing an open function slot. Architect slot count locked at exactly three per Syndicate.

One naming payoff made it in on purpose: the Tavern's minigame is blackjack — the card game — specifically because the class is named Blackjack. Small, but that's the kind of detail that only lands if someone notices the opportunity and takes it.

A Real Bug, Caught by Tests

The mid-hop combat lockout mechanic had been coded correctly from the start, but it was effectively inert under the project's old discrete-hop movement model — there was no real in-transit window for it to lock out. Moving to continuous motion made the in-transit window real, which meant the lockout mechanic suddenly mattered, and a stale test in the stairwell spec (written assuming instant-snap movement) needed correcting to drive the actual BeginHop/AdvanceMotion sequence.

Worth flagging plainly: a packing-waste overflow cap bug in the same pass was caught by the test suite, not by re-reading the code. That's the test suite doing its actual job, and it's the right way to catch this class of bug going forward.

What's Still Open

  1. UE5.8 C++ build — the spec is locked; the engine implementation is still pending.
  2. Three decks flagged as integration wiring, not standalone systems — Academy, Engine Core, and Promenade Terminal all hook into frameworks that live outside this module.
  3. Aerodrome and Garage locked as deliberately symmetric — air versus ground, same system, different configuration — still to be built out in parallel.
Blackjack Interior Spec Design Testing

Three tries at the same fix means the fix was never the problem. The assumption underneath it was.

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