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Devlog #058 - When Faithfulness Includes Bugs

Faithful reimplementation eventually reaches an uncomfortable question: what happens when the original code is wrong?

The Goods Merchant gave us two concrete examples in Darklands 483.07. One is a broken leader shortcut. The other can take the party’s money without giving it the purchased item.

Neither can be handled by quietly “improving” the reconstructed owner.

The Ctrl+F Leader Defect

The quick-reference card says Ctrl+F1 through Ctrl+F5 define the party leader. The generic input dispatcher does exactly that. The nested merchant controller intercepts the same keys, but its implementation is incomplete in a dangerous way.

Inside the merchant it changes the leader byte and repaints only the party panel. It does not update the separate transaction target, recompute the barterer text, rebuild the inventories, or recalculate displayed prices. Execution then falls through into the Purchase/Sell list-toggle block and can change which command appears active.

On leaving the merchant, the saved leader byte is restored, so even the apparent leader change is temporary.

This is now catalogued as DL-ORIG-UI-0001. SDL deliberately consumes the shortcut without mutation while the merchant controller is active. Leader selection elsewhere remains a separate original mechanism.

That is a conscious disable policy, not a failure to implement keyboard support.

Charged, but the Inventory Is Full

The second defect is more severe and is confirmed directly by instruction ordering.

Purchase subtracts money before attempting inventory insertion. The inventory owner tries compatible stacks, then appends a new record only when fewer than 64 records are occupied. If all records are occupied and no compatible stack can accept the extra quantity, insertion returns the unchanged count.

The caller does not interpret that as failure. It does not refund the price. It simply redraws the inventory.

The observable sequence is:

payment succeeds -> insertion cannot add the item -> money remains spent
-> purchased item is absent

This is narrower than “a full inventory always loses purchases.” A compatible existing stack can still accept the item, provided the quantity does not overflow FFh.

The clean controller exposes the result explicitly as InventoryFullAfterCharge. For now its SDL disposition is replicate, because reversing the operations or adding a preflight check would claim a behavior that is not in the original 483.07 owner.

Two Registers, Not One Rumor List

These discoveries led to a formal bug catalogue.

The project’s byte-confirmed register contains defects backed by exact original units and instruction ranges, together with the chosen reimplementation disposition:

  • replicate for strict compatibility;
  • correct for an explicit project fix;
  • disable when executing the original defect is unsafe or confusing;
  • pending while policy is undecided.

A separate research catalogue holds community reports from manuals, old forums, Yahoo/Groups.io archives, and earlier versions. Reports fixed before 483.07 remain historical. Reports allegedly affecting 483.07 are leads for testing, not implementation authority.

The complete versioned research catalogue is published alongside this devlog as DARKLANDS_483_07_REPORTED_BUG_CATALOGUE.md. The website hosts its own copy, including the status and confidence system, version qualifications, evidence targets, archive corrections, and suggested regression boundaries.

This distinction matters because Darklands circulated in several patched versions. Reimplementing a famous 1992 bug that was fixed in 483.07 would be just as inaccurate as silently fixing a defect that remains in 483.07.

COAB Still Follows the Original

The Certified Original-Code Boundary layer does not “repair” either defect. It preserves the original segment/offset owner, reads, writes, call order, and return behavior. That raw relation is our executable historical record.

Policy belongs above it. The clean gameplay or SDL layer may reproduce, correct, or suppress a defect, but only with a documented decision. Tests pin both the original relation and the chosen product behavior.

That separation lets the project be faithful without being careless. Bugs are not erased, accidentally amplified, or allowed to drift into folklore.