feat: checkpoint scripted battle decisions

docs/rfcs/0005-battle-runtime-checkpoints.md

@@ -15,9 +15,12 @@ references, completion is currently an `onFinish` closure, and scripted battles
 resume a suspended `ScriptRunner` coroutine. Copying the controller would create
 a record that is neither data-only nor process-independent.
 
-The engine can instead expose a narrow semantic safe point. This gives all mods
-the strongest persistent battle checkpoint the current architecture can prove,
-without claiming mid-animation or suspended-script support.
+The engine can instead expose a narrow semantic safe point. Ordinary encounters
+use fixed engine-owned completion descriptors. A scripted story encounter may
+also participate when its active command row and remaining row-list are
+detached data, its NPC can be rebound by stable object id, and its completion is
+one of the engine-declared semantic forms. The suspended coroutine itself is
+never captured.
 
 ## API delta
 
@@ -26,7 +29,7 @@ second format-1 runtime kind.
 
 ### Capability
 
-`mod.checkpoints:inspect(game)` returns this only when an ordinary single-player
+`mod.checkpoints:inspect(game)` returns this only when a supported single-player
 wild or trainer battle is settled at the player command menu:
 
 ```lua
@@ -35,13 +38,15 @@ wild or trainer battle is settled at the player command menu:
 
 The action/message queue, waits, UI, animations, HP/status presentation, and
 faint processing must be settled. The player must actually control the menu.
-The underlying overworld must have no running/queued script or scripted move,
-and the battle must carry an engine-owned semantic continuation descriptor.
+The battle must carry an engine-owned semantic continuation descriptor. An
+ordinary encounter requires an idle overworld. A scripted story encounter may
+have exactly its originating foreground runner suspended at the battle command;
+queued/parallel scripts and scripted movement remain unsafe.
 
 Additional refusal codes are `battle_phase_busy`, `battle_origin_unsupported`,
 `battle_variant_unsupported`, and `link_battle_unsupported`. Link, Safari,
-ghost, old-man/demo, fishing, static-object, script-suspended, and mod-created
-closure continuations remain rejected.
+ghost, old-man/demo, fishing, opaque callback continuations, non-data-only
+scripts, and unsupported concurrent script work remain rejected.
 
 ### Capture
 
@@ -107,10 +112,20 @@ trainer class/party, and optional header event; a win reapplies the same defeate
 flag, event, reward, and `afterBattle` path. Reconstructed overworld input and
 NPC freeze state are normalized instead of reviving the old closure.
 
-`Commands.start_battle` is deliberately unsupported: its completion closure
-mutates script context and resumes a coroutine whose program counter and Lua
-stack cannot be serialized. Existing script rejection remains the correct safe
-contract until a separate semantic ScriptRunner checkpoint RFC exists.
+For `start_battle`, `rival_battle`, and `static_battle`, the runner records the
+detached row list and current command program counter plus stable source/NPC
+identity where present. On restore, battle completion starts a fresh runner at
+that command with a one-use semantic battle result. Replaying the current
+command (rather than skipping to the next row) preserves wrapper behavior such
+as rival-party consequences, static-object removal, `lastCheck`, and deferred
+`afterBattle` evolution ordering. The reconstructed overworld starts with
+normalized input/NPC freeze state, so an engine-marked `release_npc` callback
+needs no closure revival.
+
+Arbitrary `onDone` callbacks, function-bearing rows, unknown commands, missing
+NPC identities, old-man/demo flows, and concurrent scripts fail closed. This is
+not a general ScriptRunner snapshot: no coroutine, Lua stack, local variable,
+function, or runtime object enters the checkpoint.
 
 ## Migration note
 
@@ -138,3 +153,6 @@ No-mod behavior is unchanged when checkpoints are unused.
 - exactly one post-verification `checkpoint.restored` event and none on failure;
 - legacy overworld checkpoint compatibility;
 - complete ROM-free engine and public mod-API suites.
+- scripted trainer and static/wild story continuation, including wrapper-row
+  replay, cold reconstruction, malformed row rejection, and opaque callback
+  refusal.