feedback6: merge R21A — 突袭 may land on a teammate's half when both halves are occupied (two-helper 联防, Final Assault / Hidden Core pair; the owner's decision of 2026-10-07), Battle.onFieldBoard; DESIGN §26 / §26.1 (docs/history/0.2.1.md); golden as R21A's commit (boss-boss_2/3/4/5/6-pair, hidden-boss_8/10-pair, coop4-ABYSS-7)

docs/DESIGN.md

@@ -4,7 +4,7 @@ This is the **single source of truth** for every implementer. Research lives in
 
 Language: player-facing text is **Simplified Chinese** by default, with an English switch since 0.2.0 (§25.2, docs/I18N.md: UI strings through `t('中文')`, game texts from the official Chinese data or the official EN client's). Code, comments and identifiers are English.
 
-Versions: the first public release was **0.1.0** (2026-10-02, the state of §0–§20.15); the releases after it add the player feedback and GitHub reports — 0.1.1 §21, 0.1.2 §22, 0.1.3 §23, 0.1.4 §24 — and **0.2.0** (`package.json`, `shared/constants.js APP_VERSION`; `CHANGELOG.md`) the maintainability refactor, two languages, 补位, 自选编队 and their fidelity work — §25 — and is the state described by this document. The labels v1 / v2 / v2.1–v2.5.2 in §0, §14–§20 and in the BALANCE / SIM comparisons name the design generations and the private playtest builds that came before it; they are kept as history.
+Versions: the first public release was **0.1.0** (2026-10-02, the state of §0–§20.15); the releases after it add the player feedback and GitHub reports — 0.1.1 §21, 0.1.2 §22, 0.1.3 §23, 0.1.4 §24 — and **0.2.0** (2026-10-07; `CHANGELOG.md`) the maintainability refactor, two languages, 补位, 自选编队 and their fidelity work — §25. The 0.2.1 dev line (`package.json`, `shared/constants.js APP_VERSION`: `0.2.1-dev`) adds §26 and is the state described by this document. The labels v1 / v2 / v2.1–v2.5.2 in §0, §14–§20 and in the BALANCE / SIM comparisons name the design generations and the private playtest builds that came before it; they are kept as history.
 
 ---
 
@@ -32,3 +32,4 @@ normative lines it rewrote).
 | §23 | [history/0.1.3.md](history/0.1.3.md) | 0.1.3 — community reports after 0.1.2 |
 | §24 | [history/0.1.4.md](history/0.1.4.md) | 0.1.4 — community reports after 0.1.3 |
 | §25 | [history/0.2.0.md](history/0.2.0.md) | 0.2.0 |
+| §26 | [history/0.2.1.md](history/0.2.1.md) | 0.2.1 — after the 0.2.0 release |

docs/SIM.md

@@ -842,7 +842,8 @@ instance) and skip `'counter'` / `'reflect'` damage. When the guard trips, the l
 | `addLayers(playerId, bondId, n, reason, {source})`, `addCoins(playerId, n)` | layers are a no-op when `flags.layerGainsEnabled` is false (unite/boss); a gain adds at most the room left under `BOND_LAYER_CAP` (999, shared/constants.js `layerGainRoom`: the client's `AddBondCount` min(L + n, 999)) on the live copy — or, without one, on the battle's own gains — and returns what it added (0 at the cap: no hook, no event) |
 | `getPlayer(playerId)` | `{ playerId, seat, side, colOffset, mirror, dir (default unit direction: RIGHT, mirrored side LEFT), facing (its sign), bonds (live copy, layers updated by addLayers), bandId, playerEffects, lpForBoss, dp, units }` |
 | `mapTile(ps, row, col, abs?)` / `mapDir(ps, dir, abs?)` | board → field tile / direction of a player (the FA right-side mirror) |
-| `onOwnBoard(ps, r, c)` | whether a field tile lies on the player's own board — GEO.FIELD (rows 9–12, cols 2–10) mapped onto this field: the 联防 right-hand helper's +8 columns, the boss field's rows 2–5 (never its hand / 临时整备区 rows 0–1), the mirrored right half; the 突袭 landing takes only such tiles (DESIGN §25.18), and so does 乌尔比安's S3 【移动】 (DESIGN §25.17.2) |
+| `onOwnBoard(ps, r, c)` | whether a field tile lies on the player's own board — GEO.FIELD (rows 9–12, cols 2–10) mapped onto this field: the 联防 right-hand helper's +8 columns, the boss field's rows 2–5 (never its hand / 临时整备区 rows 0–1), the mirrored right half; 乌尔比安's S3 【移动】 takes only such tiles (DESIGN §25.17.2) |
+| `onFieldBoard(r, c)` | whether a field tile lies on the board of a player of this field — `onOwnBoard` of any of `players` (the players whose units the battle holds; an eliminated or absent teammate is not one): both halves of the two-helper 联防 field and of a Final Assault / Hidden Core pair field, the own half only for a lone 联防 helper and on a solo boss field, never a boss field's hand / 临时整备区 rows; the 突袭 landing takes only such tiles (DESIGN §25.18, §26.1) |
 | `addDp(playerId, n)`, `retreat(unit, {reason, permanent, dying})`, `relocate(unit, r, c)` | `relocate` only changes the tile (state kept, no event) |
 | `moveRedeploy(unit, r, c, { clearSp })` | a 【移动】 (PRTS 术语释义: "不退场，以当前血量在目标位置部署", a special retreat + redeploy): `relocate`'s checks (false = refused, nothing changed), then a new deployment (`deploySeq` / `aggroSeq` / `deployedAt`) and `deploy {initial:false, move:true}` (deploy effects fire again); no `die` / `death`, timer or cost (不屈 / 阿戈尔's revive never see it); HP, buffs and a running skill are kept (owner's deviation, DESIGN §22.3); `clearSp` empties the SP before the deploy handlers run — 乌尔比安 S3's move (kits/ops/chess_char_5_05-ulpia.js) and 【返回】 (`clearSp`; also the 从不混淆的方向 fallback, content/tokens.js) |
 | `redeploy(unit, { free=true, tile, keepSp })` | immediate (re)deployment of a dead/retreated ally (full HP, `deploy {initial:false}`); `free: false` pays `base.cost` DP (refused without it); without `tile` it lands on the unit's rest tile (`restTile`: where a knocked-out operator lies, else home); `tile: [r, c]` lands on that tile once (home unchanged; refused when off-rect, occupied or a knocked-out operator's tile, no fallback); `keepSp` keeps SP/charges (保留技力), restored before `deploy` fires — 突袭 raids, 阿戈尔 / 不屈 revives where the unit lies |

docs/history/0.2.0.md

@@ -1379,6 +1379,10 @@ briefing types' share of the waves).
 
 #### 25.18.1 「…新约能天使在开了突袭之后蹦到了下方…临时放置溢出的干员和道具的那一栏高台」, 「单人联防时突袭也可以跑到对面的场地上」 (items 40, 16.3): 突袭 lands only on its player's own board — `sim/battle/players.js onOwnBoard`, `content/bonds/addon/battle.js raidTile`
 
+- **Changed in 0.2.1** (§26.1, the owner's decision of 2026-10-07): where both halves of the field are taken — the
+  two-helper 联防 field and a Final Assault / Hidden Core pair field — a member may land on its teammate's half too
+  (`Battle.onFieldBoard`); the hand / 临时整备区 rows, a lone helper's empty half and a solo boss field's other half stay
+  closed. This replaces the own-half rule of **Now** below on those two fields.
 - **Seen**: in a solo leader round a ranged 突袭 member (新约能天使 with the 转职球 and the 突袭手雷) jumped onto the
   boss field's 临时整备区 row; in a 联防 with one helper a member jumped onto the right half of the map.
 - **Cause**: `raidTile` took any tile of the battle rect its position may stand on (grid.canStand). BOSS_RECT holds rows

docs/history/0.2.1.md

@@ -0,0 +1,46 @@
+# DESIGN §26 — 0.2.1
+
+Part of [DESIGN.md](../DESIGN.md) (the index; section numbers are global).
+
+## 26. 0.2.1 — after the 0.2.0 release
+
+0.2.1 is built on `feedback6`, branched from the 0.2.0 release (tag v0.2.0) and marked `0.2.1-dev` until it ships. Its
+workstreams branch off it as `fb6-*`, each merged after review with its golden scenarios named. Each rule was checked
+against the official data and PRTS; anything no source backs is marked [ASSUMED]. Where each is handled: the 突袭
+landing on a teammate's half of a shared field → §26.1.
+
+Decisions of the owner: 2026-10-07 — a 突袭 member may land on a teammate's half when both halves of the field are
+taken (the two-helper 联防 field, the Final Assault / Hidden Core pair field), replacing part of §25.18.1; 乌尔比安's
+S3 【移动】 keeps his own board (§26.1).
+
+### 26.1 突袭 may land on a teammate's half when both halves are taken (the owner's decision of 2026-10-07) — `sim/battle/players.js onFieldBoard`, `content/bonds/addon/battle.js raidTile`
+
+- **Seen**: 0.2.0 (§25.18.1) let a member land only on its own board, on every field. Where both halves belong to
+  players — the two-helper 联防 field and a Final Assault / Hidden Core pair field — a member whose target stood on the
+  teammate's half stayed home or took a farther tile of its own half (reproduced: the right player's member with an
+  enemy on the left telin (1,3) of 战场#01 stayed home; on the two-helper 联防 map the left helper's member with an enemy
+  at (10,15) stayed home). After the release the owner decided that such a member may land on the teammate's half.
+- **Official**: the bond text 「保留技力立即再部署至一名地面敌人周围」 names no board, and where the official landing falls
+  among the legal tiles is not in the data (§22.2). PRTS 卫戍协议/帮助 §联防阶段: with two helpers 「两处阵地将前后拼接为一处
+  阵地，玩家在同一阵地作战」; a pair field is one boss map holding both players' boards (research 09 §1.2,
+  ConvertChessPositionInfoToBossMap). A lone helper's other half and a solo boss field's other half hold no player.
+- **Now**: `Battle.onFieldBoard(r, c)` — the tile lies on the board of a player of this field (`onOwnBoard` of any of
+  `players`, the players whose units the battle holds; the 联防 right-hand helper's +8 columns and the mirrored right half
+  of a pair are mapped as before) — and `raidTile` takes only those tiles: both halves on the two-helper 联防 field and on
+  a pair field; the own half for a lone 联防 helper (escaped_single) and on a solo boss field (nobody stands on the other
+  half; a teammate eliminated before the battle or playing another field opens nothing); never a boss field's hand row 0
+  or 临时整备区 row 1 (no board covers them). Every other landing rule is kept: ground / ranged tiles (grid.canStand),
+  free tiles (isReservedTile), a blockable tile first for a melee member (§25.11.3), a target only reachable from a
+  forbidden tile skipped (the next candidate is tried, else the member stays); the candidates are still the player's own
+  enemies first (raidTargets). 乌尔比安's S3 【移动】 keeps `onOwnBoard` (§25.17.2, a separate community report): his landing
+  never takes the teammate's half. This replaces the own-half rule of §25.18.1 on those two fields.
+- [ASSUMED]: none beyond §22.2's landing rule (which legal tile the official landing takes); with both halves open the
+  nearest covering tile wins, on whichever half it lies.
+- Golden: 8 scenarios, each parting from the parent at the first landing on a teammate's half (checked tick by tick with
+  the parent instrumented: identical up to that landing): boss-boss_2 / 3 / 4 / 5 / 6-pair, hidden-boss_8 / 10-pair (the
+  right player's 缄默德克萨斯, 伊内丝, 仇白 or 耀骑士临光 landing on the left player's half, 1–7 times per battle, the first
+  0.3–39.8 s in) and the bot match coop4-ABYSS-7 (its round-6 two-helper 联防: at 52 s ai_2's 斯卡蒂 lands on ai_1's
+  half; of the match digest only the two players' damage totals move, 8263 from ai_1 to ai_2). unite-2 is unchanged (its
+  two landings stay on their own half). Tests: `test/sim/feedback5-raid-own-board.test.js` (4 cases; the pair and the
+  two-helper cases fail on the parent; the solo boss field's hand rows, the lone helper and 乌尔比安 beside a teammate are
+  unchanged). Docs: docs/SIM.md (`onFieldBoard`; `onOwnBoard` is now 乌尔比安's only).