Add scripted event withdrawals

docs/ARCHITECTURE.md

@@ -43,7 +43,7 @@
 8. Player ends turn.
 9. Enemy AI moves, picks physical attacks from damage, defeat, priority, and weapon-effectiveness scores, and can cast single-target or area damage, healing, support, debuff, movement-modifier, accuracy/evasion-modifier, damage-over-time, or action-lock tactics through the same combat and skill resolvers.
 10. Battle checks scenario-defined defeat conditions first, including commander loss and turn limits, then victory conditions such as enemy defeat or reaching a marked destination tile.
-11. Turn-start and movement-triggered scenario events run as phases change or units enter marked cells, and may update objectives with HUD notices, grant inventory pickups, or deploy reinforcements.
+11. Turn-start and movement-triggered scenario events run as phases change or units enter marked cells, and may update objectives with HUD notices, grant inventory pickups, deploy reinforcements, or withdraw units from the battlefield.
 12. On first-time victory, `CampaignState` snapshots player progression and the battle inventory, applies rewards once, advances `current_scenario_id`, and writes `user://campaign_save.json`.
 13. If the scenario defines post-battle dialogue, it plays once before the victory result panel opens.
 14. The victory result panel splits rewards, roster changes, saved player growth, campaign status, and pending choices into sections.

docs/DATA_MODEL.md

@@ -465,7 +465,7 @@ Conditions may include `after_event` to stay inactive until a one-shot event has
 
 `post_battle_choices` are shown on the victory result panel after first-time scenario rewards are applied. Each choice needs a unique stable lowercase `id`, a non-empty `label`, and a `set_flags` object whose keys are stable lowercase flag ids. Choices may also grant positive `gold`, known `items`, `join_officers`, and `leave_officers`. When rewards are saved but the player has not selected a choice yet, `CampaignState.pending_post_battle_choice_scenario_id` records that scenario id so reloading the game returns to the victory choice panel instead of skipping the branch. The selected choice is saved to `CampaignState.flags`, `CampaignState.applied_post_battle_choices`, and campaign membership only when the player presses its result-panel button; completed-scenario replays do not show choices again. Save-load migration for older saves uses flags as a conservative choice signal, so avoid designing multiple choices in one scenario that can all match the same saved flag state.
 
-Scenario `events` support `battle_start`, `battle_begin`, `turn_start`, and movement-triggered `unit_reaches_tile` triggers. Each event needs a stable lowercase `id` that is unique within the scenario; `after_event` conditions can only reference those explicit ids. `battle_begin` runs after the briefing is closed. `unit_reaches_tile` events run when a moved unit enters the zero-based `pos` cell; use `team`, `unit_ids`, or `officer_ids` to limit who can trigger the event. Actions currently include `log`, `dialogue`, `set_objective`, `grant_item`, `grant_items`, `spawn_deployment`, and `spawn_deployments`. `set_objective` updates visible objective text, emits concrete log lines for changed victory/defeat text, and raises an objective-update signal so the battle scene can refresh the HUD and show a short notice. Event `dialogue` actions use the same dialogue line format, portrait default rules, and optional `side` placement as `post_battle_dialogue`. Event item grants add to the battle inventory immediately; they persist to the campaign save only when the battle is won.
+Scenario `events` support `battle_start`, `battle_begin`, `turn_start`, and movement-triggered `unit_reaches_tile` triggers. Each event needs a stable lowercase `id` that is unique within the scenario; `after_event` conditions can only reference those explicit ids. `battle_begin` runs after the briefing is closed. `unit_reaches_tile` events run when a moved unit enters the zero-based `pos` cell; use `team`, `unit_ids`, or `officer_ids` to limit who can trigger the event. Actions currently include `log`, `dialogue`, `set_objective`, `grant_item`, `grant_items`, `spawn_deployment`, `spawn_deployments`, `withdraw_unit`, and `withdraw_units`. `set_objective` updates visible objective text, emits concrete log lines for changed victory/defeat text, and raises an objective-update signal so the battle scene can refresh the HUD and show a short notice. `withdraw_unit` accepts `unit_id` or `id`, while `withdraw_units` accepts a `unit_ids` array; living deployed targets leave the battlefield without being marked defeated, so they are removed from map occupancy and living-unit counts while protected-unit defeat checks still distinguish withdrawal from death. Event `dialogue` actions use the same dialogue line format, portrait default rules, and optional `side` placement as `post_battle_dialogue`. Event item grants add to the battle inventory immediately; they persist to the campaign save only when the battle is won.
 
 ```json
 {
@@ -487,6 +487,7 @@ Scenario `events` support `battle_start`, `battle_begin`, `turn_start`, and move
     },
     { "type": "set_objective", "victory": "Defeat the vanguard and reinforcements." },
     { "type": "grant_item", "item_id": "bean" },
+    { "type": "withdraw_units", "unit_ids": ["enemy_scout_1", "enemy_scout_2"] },
     {
       "type": "spawn_deployment",
       "deployment": {
@@ -563,4 +564,4 @@ Before a battle starts, `BattleScene` can buy priced items through `CampaignStat
 
 When every campaign scenario id is present in `completed_scenarios`, the battle scene shows a campaign completion panel. Starting a new campaign clears the automatic save file and resets `current_scenario_id` to `start_scenario`; the manual checkpoint is left alone until overwritten from the Save menu.
 
-Run `tools/validate_data.ps1` after data edits to check campaign paths, chapter ranges, map dimensions, terrain keys, class/officer/item/skill references, skill area shapes, skill status/action-lock effect shapes, item effect names and cure statuses, officer and deployment portraits, officer and deployment equipment slot compatibility including accessory types and weapon effectiveness fields, promotion routes and promotion equipment compatibility, condition/event names, event item grants, condition unit references, destination condition coordinates, campaign flag references, joined-officer gates, briefing line blocks, deployment ids, deployment bounds, impassable spawn cells, shop stock, roster rules, formation cells, post-battle dialogue, post-battle choices, and reward item ids.
+Run `tools/validate_data.ps1` after data edits to check campaign paths, chapter ranges, map dimensions, terrain keys, class/officer/item/skill references, skill area shapes, skill status/action-lock effect shapes, item effect names and cure statuses, officer and deployment portraits, officer and deployment equipment slot compatibility including accessory types and weapon effectiveness fields, promotion routes and promotion equipment compatibility, condition/event names, event item grants, event withdrawal unit ids, condition unit references, destination condition coordinates, campaign flag references, joined-officer gates, briefing line blocks, deployment ids, deployment bounds, impassable spawn cells, shop stock, roster rules, formation cells, post-battle dialogue, post-battle choices, and reward item ids.

docs/GODOT_4_6_MIGRATION.md

@@ -50,6 +50,7 @@ powershell -NoProfile -ExecutionPolicy Bypass -File tools\check_godot46_readines
 - Hovering an occupied tile shows the unit's class, movement type, AGI, movement, range, equipped weapon/armor/accessory, and a HUD portrait thumbnail when no unit is selected, with empty gear slots shown as `-`.
 - The battle HUD and briefing objective panels split objective, progress, and risk details, including pending unlocks, destination reach status, defeated enemy counts, named protected-unit or commander safety, and turns remaining.
 - `set_objective` scenario events show concrete objective-update logs, play a UI confirmation sound, refresh the HUD immediately, and briefly show the objective notice panel.
+- `withdraw_unit` and `withdraw_units` scenario events remove living targets from the battlefield without marking them defeated.
 - Movement-triggered supply cache events grant battle inventory items with pickup feedback, and the items persist only after victory.
 - The Threat toggle or `Y` key shows enemy physical and hostile tactic reach, hovered threatened tiles name the threatening units, and occupied player tiles show physical damage/hit estimates plus hostile tactic damage or status hints.
 - Area tactics such as Blaze, Great Mend, and Poison Mist highlight affected cells, apply only to valid targets in the area, and spend MP once per cast.

docs/ROADMAP.md

@@ -43,10 +43,10 @@
 
 - Pre-battle briefing exists with a campaign chapter header, battle header, objective summary, and condition tracker. Full dialogue scenes are still planned.
 - Scenario events exist for battle start, battle begin, turn start, movement-triggered map tiles, and objective-change notices.
-- Mid-battle map/action events have a first action system with movement ambushes.
+- Mid-battle map/action events have a first action system with movement ambushes and scripted unit withdrawals.
 - Opening battle dialogue exists through event actions.
 - Post-battle dialogue exists before the victory result panel.
-- Reinforcements, objective changes with HUD/log feedback, and inventory pickup events exist in a basic form.
+- Reinforcements, scripted unit withdrawals, objective changes with HUD/log feedback, and inventory pickup events exist in a basic form.
 - Post-battle reward save, campaign choice flags, first flag-driven briefing/shop/event branches, sectioned result summaries, and choice reward previews exist in a basic form. Richer reward screens and wider branch support are still planned.
 
 ## Milestone 4: Campaign Progression