refactor(runtime): own combat and magic intent

Move attack build/repeat state, combat-mode policy, authoritative auto-target transitions, and spell-cast intent beneath RuntimeActionState. Keep App as the input, world-query, DAT-policy, transport, and presentation adapter while preserving retail request and busy ordering. Add direct/graphical parity, reset, failure, and instance-isolation coverage.

Co-authored-by: Codex <noreply@openai.com>

docs/research/2026-07-26-slice-j5-3-combat-magic-intent.md

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+# Slice J5.3 — retail combat and magic intent ownership
+
+## Scope
+
+This note pins the retail ordering that must remain unchanged while the
+presentation-independent combat and casting state moves from `AcDream.App` to
+`AcDream.Runtime`. The move changes ownership and command types only. ACE
+remains authoritative for combat mode settlement, attacks, casts, damage,
+motion, component consumption, effects, and completion.
+
+Primary oracle:
+`docs/research/named-retail/acclient_2013_pseudo_c.txt`.
+
+Cross-checks:
+
+- the ACE/ACViewer request-layout cross-checks pinned in
+  `docs/research/2026-07-11-retail-combat-bar-pseudocode.md` and
+  `docs/research/2026-07-15-retail-magic-ui-and-casting-pseudocode.md`;
+- the ACE corpse/death-state cross-check pinned in
+  `docs/research/2026-07-12-death-and-auto-target-pseudocode.md`;
+- existing conformance ports in
+  `src/AcDream.Core/Combat/CombatModel.cs` and
+  `src/AcDream.Core/Spells/RetailSpellTargetPolicy.cs`
+
+## Named retail mechanisms
+
+### `ClientCombatSystem::Begin @ 0x0056A460`
+
+Pseudocode:
+
+```text
+combatMode = NonCombat
+pendingCombatMode = Undefined
+clear jump and power-bar timing
+clear request, server-pending, queued-request, attack, and repeat state
+requestedPower = 0
+requestedHeight = Medium
+desiredUiPower = 0.5
+trackingTarget = false
+advancedCombat = false
+```
+
+This is the session-reset state of the Runtime combat-intent owner.
+
+### `ClientCombatSystem::StartAttackRequest @ 0x0056C040`
+
+Pseudocode:
+
+```text
+target = GetAttackTarget()
+if advanced combat or (target exists and ObjectIsAttackable(target)):
+    attackRequestInProgress = true
+    requestedAttackPower = 1.0
+    FinishJump()
+    MaybeStopCompletely()
+    currentBuildIsAutomatic = false
+    AttemptStartBuildingAttack()
+else:
+    display the retail invalid-target notice
+```
+
+The request flags commit before the shared movement owner is asked to finish
+jump/stop. The host operation preserves that exact boundary and may publish
+the resulting movement packet before a later attack send.
+
+### `StartPowerBarBuild @ 0x0056ADB0`,
+`EndAttackRequest @ 0x0056C0E0`, and `UseTime @ 0x0056C1F0`
+
+Pseudocode:
+
+```text
+StartPowerBarBuild:
+    buildInProgress = true
+    buildStartTime = current game time
+    publish level 0
+    latestPowerBarLevel = 0
+
+EndAttackRequest:
+    if no request: return
+    requestInProgress = false
+    currentLevel = GetPowerBarLevel()
+    requestedPower = explicit power, advanced current level,
+                     or min(desiredUiPower, currentLevel)
+    if server response pending:
+        remember one queued release
+    else if desired power reached or repeating:
+        ExecuteAttack()
+
+UseTime:
+    while building, publish the current level
+    if the player is not ready, cancel/reset according to repeat state
+    after release, execute once the captured requested level is reached
+```
+
+### `AbortAutomaticAttack @ 0x0056AE90`
+
+If a request, attack, server response, or repeat is active, retail sends
+`Event_CancelAttack`, clears repeat, and hides the combat power build.
+`ACCmdInterp::HandleNewForwardMovement @ 0x0058B1F0` invokes this before the
+new forward movement enters the interpreter. Runtime therefore receives a
+typed movement-abort command at that existing ordering boundary.
+
+### `HandleAttackDoneEvent @ 0x0056C500`
+
+Retail releases the attack busy reference (when held), clears server-pending
+state, aborts repeat on authoritative error, starts the next automatic build
+or attack only when repeat remains enabled, and finally drains the one queued
+release. Runtime must never predict completion.
+
+### `GetDefaultCombatMode @ 0x0056B310` and
+`ToggleCombatMode @ 0x0056C8C0`
+
+From non-combat, retail scans equipped contents in inventory-placement order:
+missile equipment selects Missile, a caster in Held selects Magic, ordinary
+melee/two-handed equipment selects Melee, and an incompatible Held item
+rejects the transition with its item-name notice. With no weapon it selects
+unarmed Melee. From any combat mode, Toggle selects NonCombat without running
+the default scan.
+
+The exact decision remains the existing Core port
+`CombatInputPlanner.GetDefaultCombatModeDecision`; Runtime owns the command
+state and App supplies ordered equipment plus transport/presentation sinks.
+
+### `RecvNotice_SelectionChanged @ 0x0056BD80` and
+`AutoTarget @ 0x0056BC80`
+
+When selection becomes zero in Melee/Missile mode and Auto Target is enabled,
+retail enters its next-target selection path. An authoritative Dead motion
+makes the current target unavailable and reaches the same selection-change
+path. Runtime owns the identity transition; App supplies the world query that
+selects the closest retail-compatible hostile.
+
+### `ClientMagicSystem::CastSpell @ 0x00568040`
+
+Pseudocode:
+
+```text
+resolve the exact known spell metadata
+if components are required:
+    resolve the appropriate formula
+    reject when a required component is unavailable
+resolve self, untargeted, or selected target
+validate the target against the spell target mask
+FreeHandsAndCastSpell(spellId, targetId)
+```
+
+### `ClientMagicSystem::FreeHandsAndCastSpell @ 0x00566EF0`
+
+Pseudocode:
+
+```text
+MaybeStopCompletely()
+if targetId == 0:
+    Event_CastUntargetedSpell(spellId)
+else:
+    Event_CastTargetedSpell(targetId, spellId)
+IncrementBusyCount()
+```
+
+The cast owner therefore stops first, emits exactly one packet, and increments
+the shared busy reference only after a successful send. It does not locally
+turn the avatar: retail sends after `MaybeStopCompletely`, and the
+authoritative server turn/cast motion supplies the visible facing. Send
+failure clears the remembered request and cannot increment busy.
+
+`ClientMagicSystem::OnEndCharacterSession @ 0x00566F50` clears selected and
+targeting spell state, which maps to Runtime session reset.
+
+## Ownership result
+
+Runtime owns:
+
+- attack build/request/repeat/queued-release state and time;
+- typed attack commands and movement-abort intent;
+- combat-mode command policy;
+- authoritative target-death/auto-target identity transitions;
+- cast validation intent and last requested spell/target;
+- reset, teardown, revisions, and presentation-independent snapshots.
+
+App retains:
+
+- input-key and retained-widget mapping;
+- ordered equipped-object and closest-hostile world queries;
+- local movement preparation and outbound transport;
+- target/spell compatibility data that depends on the live object table;
+- DAT spell catalog/formulas/components/icons;
+- messages, bars, animations, audio, particles, and camera presentation.
+
+No new retail divergence is introduced by this ownership move.