docs(phys L.2g): design spec for dynamic PhysicsState toggling (doors)

L.2d slice 1.5 ship identified the Holtburg doorway blocker as a closed
Door entity (Setup 0x020019FF) whose PhysicsState.Ethereal bit flips
when the player Uses the door. The L.2d shape-fidelity work doesn't
cover this — the door's collision shape is correct; what's missing is
honoring the *runtime* state change.

L.2g is the new sub-phase that handles it. Scope is narrow:

  * Parse inbound GameMessageSetState (0xF74B).
  * Plumb the new PhysicsState value into ShadowObjectRegistry's
    cached per-entity state so the existing CollisionExemption.IsExempt
    already-in-place short-circuit sees up-to-date bits.
  * Verify the Holtburg inn-door scenario: walk in blocked, Use door,
    walk through, auto-close blocks again after 30s.
  * Confirm UpdateMotion (NonCombat, On/Off) drives non-creature
    entities (door swing animation).

Why a new L.2 sub-letter (and not B.4 or Door-special-case): the wire
mechanism (SetState flipping Ethereal) is also how ACE handles activated
traps, opened chests, spell projectiles becoming ethereal. Generic
infrastructure with doors as the verification scenario; lane is the
informal sixth "dynamic state."

Roadmap state:
  * L.2 plan-of-record adds the L.2g section after L.2f.
  * Milestones doc M1 phase list extended `a-f` -> `a-g`.
  * CLAUDE.md status pointer + "next phase candidates" list updated to
    name L.2g slice 1 implementation as the natural next step.

Risk: low. Wire-byte width has a hex-dump fallback path in slice 1
(holtburger says 12 bytes, ACE writes 16, capture settles it). ETHEREAL
plumbing already exists; we feed it new data. No resolver changes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/plans/2026-04-29-movement-collision-conformance.md

@@ -228,6 +228,44 @@ client sees when observing acdream.
 - Require conformance notes in tests or research docs for every AC-specific
   algorithm ported under L.2.
 
+### L.2g - Dynamic PhysicsState Toggling
+
+Goal: server-driven post-spawn state changes (chiefly `ETHEREAL` flips) are
+honored by the local collision stack.
+
+Triggered 2026-05-12 evening by the L.2d slice 1.5 trace: the Holtburg
+doorway blocker is a closed Door entity (Setup `0x020019FF`) whose
+`PhysicsState.Ethereal` bit flips when the player Uses the door. The L.2d
+shape-fidelity work doesn't cover this — the door's collision shape is
+already correct; what's missing is honoring the *runtime* state change.
+
+Scope is intentionally narrow:
+
+- Parse inbound `GameMessageSetState (opcode 0xF74B)`.
+- Plumb the new `PhysicsState` value into `ShadowObjectRegistry`'s cached
+  per-entity state so the existing `CollisionExemption.IsExempt(...)` check
+  sees the up-to-date bits.
+- Verify the Holtburg inn-door scenario: walk into doorway → blocked, Use
+  door → door swings open AND player can walk through, auto-close after
+  30s → door closes AND player is blocked again.
+- Confirm the existing `UpdateMotion` pipeline drives `(NonCombat, On/Off)`
+  on non-creature entities (door swing animation). If not, one-line fix.
+
+Excluded from L.2g scope (deferred):
+
+- Door-specific UX polish: "door is locked" sound, creature-AI bump-open.
+- Any Door-specific class hierarchy — generic state-flip infrastructure
+  is enough; doors are the verification scenario, not a privileged case.
+
+Lane: informal sixth lane "dynamic state." The existing five-lane table
+treats per-entity state as static-after-spawn; L.2g makes it dynamic.
+
+Full design spec:
+[docs/superpowers/specs/2026-05-12-l2g-dynamic-physicsstate-design.md](../superpowers/specs/2026-05-12-l2g-dynamic-physicsstate-design.md).
+
+M1 critical path: this slice unblocks the *"open the inn door"* demo
+scenario.
+
 ## Named Retail Anchors
 
 Primary source: `docs/research/named-retail/acclient_2013_pseudo_c.txt`.

docs/plans/2026-05-12-milestones.md

@@ -101,9 +101,13 @@ doorway. Open the inn door. Click an NPC and see selection feedback. Pick
 up an item from the ground.
 
 **Phases to ship:**
-- **L.2 (all sub-lanes a–f)** — Movement & Collision Conformance. Currently
-  active; L.2a slices 1+2+3 shipped 2026-05-12.
-- **B.4** — `Use` / `UseWithTarget` / `PickUp` outbound messages.
+- **L.2 (all sub-lanes a–g)** — Movement & Collision Conformance. Currently
+  active; L.2a slices 1+2+3 + L.2d slice 1+1.5 shipped 2026-05-12. L.2g
+  (dynamic PhysicsState toggling — doors) brainstormed + design-spec'd
+  2026-05-12 evening, implementation next.
+- **B.4** — `Use` / `UseWithTarget` / `PickUp` outbound messages
+  (shipped 2026-04-28; remains in M1 scope until L.2g completes the
+  inbound-state half of the Use round-trip).
 
 **Freeze on landing:**
 - L.2 zone (collision, cell ownership, transition parity, wire authority)