[calebl]

What

G1 from the design research report: the doctor's "the arc can complete" check (P3) ignored locks. It walked every connection row, so a world whose key lay behind its own door passed as completable.

• Story::Doctor#reachable_from_the_opening is now lock-aware. A keyed door opens only once its key, or any lockpick (the engine's pick choice), lies somewhere already reached. The walk repeats until the set of keys in hand stops growing, so chained keys are followed and a key behind its own lock, or a cycle of keys behind each other's locks, opens nothing. A jammed door always counts as passable, because force needs no tool. Where a door has rows in both directions, each direction follows its own row; where only one row is recorded, the walk uses that row both ways, as before.
• New warning lock_whose_key_lies_behind_it (remedy manual). It names each door the walk leaves shut with its far side out of reach, and says where the key is: on the far side of that same door, behind another lock whose key is also out of reach, or nowhere reachable. Any arc target behind such a door is still reported as the fatal quest_target_unreachable. A door whose near side is itself out of reach is not reported; the lock in front of it is the one to fix.
• New sweep world lib/engine_sweep/worlds/a-key-locked-in-with-its-door.yml trips both findings: one key behind its own door, and two keys behind each other's doors. EngineSweepTest lets this world, and only this world, carry those two findings. No sweep script walks it, because scripts play against engine-vendored goldens.
• Story::DoctorLocksTest covers passing and failing cases: a key on the near side, a key in the protagonist's starting hands, a chain of keys, a reachable lockpick, a jammed door, a key behind its own lock, a two-key cycle, and the sweep world. SeededWorldsTest's arc findings now include the new code.

The doctor still only reads and reports. It never changes a world.

Idea source: Scouten2/LevelDesignSkill graph_check.py (MIT). This is a Ruby reimplementation over the doctor's own records; no code was copied.

Every world doctored

The doctor was run over every hand-made world in db/seeds/worlds/ and every sweep world. No hand-made world fails. The only world with either finding is the new one. a-key-for-the-other-door keeps a key behind its own lock but passes, because a lockpick lies in the opening room.

Checks

The full suite passes except two ViewportPinControllerTest cases that failed on the second run with a headless Chromium/dbus error. They are unrelated to this change, and they passed on the first full run. rubocop, zeitwerk:check and brakeman are clean. bin/rails engine:rust_gates passes on all 114 scripts. No model calls were made: the model keys were unset.