MVP M1–M3: visual port, TipTap text editor, React Flow diagram

apps/web — Next.js 16 + TypeScript + React 19 (no Tailwind)

M1 Visual port
- Manuscript theme + base styles ported verbatim from design-source
- 100dvh layout with internal scroll regions (rail / narrative / dock thread)
- TopBar, LeftRail (collapsible sections + collapsed strip), CanvasHeader,
  StatusBar, EditorShell composing the dual-canvas
- SocratesDock (subtle/default/prominent) with bubbles + numbered options
- Sigil (Σ + laurel) used across editor and seed screens
- SeedScreen with emerging-seed rail, mini-graph, confidence bar, thread,
  typing indicator, input row
- Routes: / (homepage), /editor/[projectId], /seed
- Aristotle fixture in lib/fixtures (ported from data.js)

M2 Real text editor
- TipTap (StarterKit + custom Chip atom inline node + ReactNodeViewRenderer)
- Slash-menu insertion via @tiptap/suggestion with arrow / number-key shortcuts
- ChipFocusContext bridges narrative ↔ diagram hover/selection across the
  TipTap render boundary
- fixtureToDoc converts the fixture narrative → ProseMirror JSON

M3 Real diagram
- React Flow (@xyflow/react) custom node (block / actor / constraint / system)
  matching prototype's softened look
- Custom edge with bezier path + label renderer (association / composition /
  constraint variants)
- Drag-create from a left-side palette via HTML5 DnD + screenToFlowPosition
- NodeInspector panel: edit kind / label / properties (or expression for
  constraints); delete cascades to incident edges
- Bidirectional focus highlighting between chips (narrative) and blocks
  (diagram)
- Removed redundant legend (stereotype labels on nodes serve same purpose)

State for M3 lives in component memory; persistence + bidirectional sync land
in M4–M5.

apps/web/components/text-canvas/SlashExtension.ts

@@ -0,0 +1,20 @@
+// TipTap extension wrapping the slash-menu suggestion plugin.
+
+"use client";
+
+import { Extension } from "@tiptap/core";
+import Suggestion from "@tiptap/suggestion";
+import { slashSuggestion } from "./slashSuggestion";
+
+export const SlashExtension = Extension.create({
+  name: "slashMenu",
+
+  addProseMirrorPlugins() {
+    return [
+      Suggestion({
+        editor: this.editor,
+        ...slashSuggestion,
+      }),
+    ];
+  },
+});