docs(D.2b): chat-window re-drive session handoff (Plan 2 chat piece)

Captures: current hand-authored chat window (UiNineSlicePanel + UiChatView,
read-only, debug font), the importer toolkit to reuse, the retail gmMainChatUI
oracles, the open design questions (scope / behavioral widgets / dat font), and
the first research step (find the chat LayoutDesc id). Resume via brainstorming.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/research/2026-06-15-chat-window-redrive-handoff.md

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+# Chat-window re-drive — session handoff (2026-06-15)
+
+**Status:** brainstorm STARTED (context gathered, design questions open) — not yet
+designed or implemented. Resume with `superpowers:brainstorming`.
+
+**Branch:** `claude/hopeful-maxwell-214a12` — **continue UI work HERE** (the user's
+call: UI stays on this branch; dungeon lighting / M1.5 goes to a *separate* branch
+off `main`, it's unrelated and easy to merge). This branch is already current with
+`main` (merged `5ac9d8c`).
+
+---
+
+## Where we are (what shipped this session)
+
+**D.2b LayoutDesc importer — Plan 1 SHIPPED + flipped to default + post-flip fixes.**
+The vitals window is now data-driven from the dat `LayoutDesc 0x2100006C` (no
+per-window graphics code). Read **`claude-memory/project_d2b_retail_ui.md`** (the
+SSOT crib) FIRST — it has the full architecture + every correction. Key commits:
+
+- `bf77a23` — flip: importer is the default vitals at `ACDREAM_RETAIL_UI=1`; the
+  hand-authored `vitals.xml` + the `ACDREAM_RETAIL_UI_IMPORTER` flag were retired.
+- `8aa643f` — horizontal resize: edge-anchor mapping corrected to retail
+  `UIElement::UpdateForParentSizeChange @0x00462640` (`RightEdge==1`=stretch).
+- `43064ba` — stamina/mana numbers: `TextRenderer` now draws sprites in
+  **submission (painter) order** (was per-texture batched → later bars overpainted
+  their own numbers).
+- `34243f2` — number sharpness: `DrawStringDat` **pixel-snaps** each glyph dest.
+
+**The importer toolkit to REUSE (all in `src/AcDream.App/UI/Layout/`):**
+- `ElementReader` — `ElementInfo` POCO + `Merge` (BaseElement/BaseLayoutId
+  inheritance) + `ToAnchors` (edge-flag → AnchorEdges, decomp-correct).
+- `UiDatElement` — generic per-DrawMode sprite renderer (the fallback widget).
+- `DatWidgetFactory` — `Type → widget` hybrid: Type 7→`UiMeter`, 12→skip, else
+  generic; sets rect + anchors + `ZOrder=ReadOrder`. **Behavioral Types map to a
+  dedicated widget; the widget CONSUMES the element's children (leaf — importer
+  does not recurse them).** This is the pattern the chat re-drive extends.
+- `LayoutImporter` — `Import`/`ImportInfos`/`Build`/`BuildFromInfos` + cycle-guarded
+  `Resolve`. `ImportedLayout.FindElement(id)` for binding by id.
+- `VitalsController` — binds live data to widgets by element id (mirrors retail
+  `gmVitalsUI::PostInit`). The chat controller will mirror this.
+- Format reference: **`docs/research/2026-06-15-layoutdesc-format.md`** (ElementDesc
+  API, Type table, DrawMode, inheritance). NOTE its §4 edge-flag history: the FIRST
+  reading was inverted; the CORRECT model (per `@0x00462640`) is now in the doc +
+  `ToAnchors` — `RightEdge==1`=stretch, `LeftEdge==2`=track-right.
+
+---
+
+## Next task: re-drive the chat window through the importer (Plan 2 chat piece)
+
+Today the chat window is **hand-authored**, not data-driven. The goal mirrors the
+vitals re-drive: read the chat window's dat `LayoutDesc`, build it via
+`LayoutImporter`, and bind the live chat through a `ChatController`.
+
+### Current chat window (what to reproduce / replace)
+- Built in `src/AcDream.App/Rendering/GameWindow.cs` in the `if (_options.RetailUi)`
+  block (~line 1836, "Retail chat window").
+- `UiNineSlicePanel` (hand-authored 8-piece chrome) at `(10,432)`, `440×184`,
+  `MinWidth 180 / MinHeight 80`, draggable + resizable.
+- Hosts a `UiChatView` (`src/AcDream.App/UI/UiChatView.cs`): scrollable transcript,
+  **bottom-pinned**, mouse-wheel scrollback, **drag-select + Ctrl+C copy + Ctrl+A**,
+  whole-line vertical clipping. **READ-ONLY** (no input box). Uses the **debug
+  bitmap font** (`_debugFont`), NOT the dat font. `LinesProvider` polled each frame.
+- Data: `ChatVM` (`displayLimit: 200`) → `RecentLinesDetailed()` → per-`ChatKind`
+  colour via `RetailChatColor(...)` (local static in GameWindow).
+
+### Chat pipeline (already shipped, Phase I — reuse, don't rebuild)
+`ChatLog (Core) → ChatVM (UI.Abstractions) → view`; outbound `input →
+ChatInputParser → LiveCommandBus → WorldSession`. See
+`claude-memory/project_chat_pipeline.md`. The re-drive is a VIEW/layout change; the
+pipeline stays.
+
+### Retail chat UI classes (decomp oracles — analogous to gmVitalsUI)
+`gmMainChatUI`, `gmFloatyMainChatUI`, `gmFloatyChatUI`, `gmChatOptionsUI`
+(`docs/research/named-retail/acclient.h` ~line 54923; `symbols.json` has
+`gmMainChatUI::Register` etc.). Chat-layout notes:
+`docs/research/retail-ui/05-panels.md:120` (chat window layout) +
+`06-hud-and-assets.md:651` (every chat window layout is a `LayoutDesc`).
+
+### FIRST research step (the Task-1 analogue): identify the chat `LayoutDesc` id
+The vitals id was `0x2100006C`; the chat window's id is **NOT yet known**. Find it:
+- `dump-vitals-layout <datdir> [0xId]` enumerates LayoutDescs (it already lists all
+  layouts containing given element ids). Use it to scan for the chat window, or grep
+  the decomp for the layout id referenced by `gmMainChatUI`/`gmFloatyMainChatUI`.
+- Then dump it and enumerate its element Types (expect a scroll/list region +
+  scrollbar, maybe a text-input/edit element + channel tabs) — this drives the
+  factory/widget work.
+
+---
+
+## Open design questions (resume the brainstorm here)
+
+1. **Scope.** Re-drive the EXISTING read-only window (frame from dat + reuse
+   `UiChatView` for the transcript, parity with today), OR expand to the FULL retail
+   chat (input box for typing, channel tabs)? Recommendation to discuss: do the
+   frame re-drive + transcript first (parity), defer input/tabs to a follow-up —
+   but confirm with the user.
+2. **Behavioral widgets.** The chat dat layout introduces the long-tail Types the
+   vitals didn't have — Type 5 `ListBox`, Type 0xB `Scrollbar`, maybe Type 0xC
+   `Text`/edit. Two options:
+   - **(A, recommended) Hybrid reuse** — like Type-7→`UiMeter`: map the transcript
+     region's Type → the existing `UiChatView` (which already scrolls/selects/copies);
+     a `ChatController` binds the tail by element id. Minimal new code; fastest parity.
+   - **(B) Port faithful widgets** — implement `UiScrollbar`/`UiListBox` per the
+     decomp so the dat's scrollbar element drives scrolling. More faithful, more work;
+     better as a later step.
+3. **Dat font for the transcript.** Switch `UiChatView` from the debug bitmap font
+   to the dat font (`UiDatFont`, faithful + now pixel-snapped) — OR keep the debug
+   font for parity first? `UiChatView`'s measure/selection logic is `BitmapFont`-based,
+   so a dat-font port is non-trivial (a `UiDatFont` measure/advance path + selection
+   hit-test rework). Likely a follow-up, not the first cut.
+
+---
+
+## Watchouts / lessons (don't regress these)
+- **`TextRenderer` draws sprites in submission order** (`_spriteSegs`). Do NOT revert
+  to per-texture batching — it overpaints later same-atlas text (the stamina/mana bug).
+- **`DrawStringDat` pixel-snaps glyphs.** Keep it (sharp text on resize).
+- **Edge-flag/anchor model is `@0x00462640`** (`RightEdge==1`=stretch). The format
+  doc §4's first reading was inverted; trust the corrected `ToAnchors`.
+- **Behavioral widgets are leaf** — the factory's widget consumes the element's dat
+  children; the importer doesn't recurse into them. Apply the same to the chat
+  transcript widget.
+- **Don't fabricate dat reader internals** — `Chorizite.DatReaderWriter` is a NuGet
+  package (not in `references/`); verify member names via the dump tool / reflection.
+
+## Process for the next session
+1. Read `claude-memory/project_d2b_retail_ui.md`, this handoff, and
+   `docs/research/2026-06-15-layoutdesc-format.md`.
+2. Resume `superpowers:brainstorming` — settle scope + behavioral-widget approach
+   (the 3 questions above), present a design, write the spec.
+3. Then `superpowers:writing-plans` → `superpowers:subagent-driven-development`
+   (same flow that shipped the vitals importer cleanly).
+4. Stay on `claude/hopeful-maxwell-214a12`. Visual checks: launch live (ACE on
+   `127.0.0.1:9000`) with `ACDREAM_RETAIL_UI=1`; test accounts `testaccount2 /
+   testpassword2` or `notan / MittSnus81!` (character `+Je`).