Shell/core import law: public API barrels + ESLint enforcement (stage 2)

The shell now imports through exactly two barrels, enforced by
import/no-restricted-paths (npm run lint):

  components/**  ->  "@/src/core"      (pure core API, browser-safe)
  app/**         ->  "@/src/core" + "@/src/server" (server entries)

Zone violations are lint errors with architecture-pointer messages; the
pure-core modules (contracts, question-core, plan-tree, phases, pending,
math-delims, ui-message) may never import agent/server/store.

Supporting moves (direction: IO layers -> core):
- core/index.ts: the core public API barrel
- core/ui-message.ts: moved from src/agent (it was shell-facing all along)
- quiz/ask input zod schemas moved agent/tools -> core/question-core
  (the question contract, alongside the grading logic)
- ChatRecord/ChatSummary moved store/chats -> core/contracts (single schema)
- GraphSnapshot/NodeStateClass moved core/graph -> core/contracts (the
  /api/graph payload IS a contract; the pure renderer needs only these)
- src/server/{chats,graph,jobs}.ts + index.ts: thin server entries for the
  transport layer; GET /api/graph's fold side-effect now lives behind
  graphView() instead of inline in the route

Gates: tsc clean, 190/190 tests, eslint clean (law verified to fire on
store/agent/subpath violations), production build clean.

(Repo repair en route: a git object (app/chat/[id] tree) was missing from
the object store — reconstructed byte-exactly via mktree from its blob;
the broken node_modules that stalled the build was cleanly reinstalled.)

components/ai-elements/message.tsx

@@ -36,7 +36,7 @@ import {
   type PluginConfig,
 } from "streamdown";
 import { MermaidError } from "@/components/mermaid-error.tsx";
-import { transformMathDelimiters } from "@/src/core/math-delims.ts";
+import { transformMathDelimiters } from "@/src/core";
 
 export type MessageProps = HTMLAttributes<HTMLDivElement> & {
   from: UIMessage["role"];

components/ai-elements/reasoning.tsx

@@ -21,7 +21,7 @@ import {
 } from "react";
 import { Streamdown } from "streamdown";
 
-import { transformMathDelimiters } from "@/src/core/math-delims";
+import { transformMathDelimiters } from "@/src/core";
 import { mermaidOptions, streamdownPlugins } from "./message";
 import { Shimmer } from "./shimmer";
 

components/answered-card.tsx

@@ -2,7 +2,7 @@
 
 import { cn } from "@/lib/utils";
 import { MessageResponse } from "@/components/ai-elements/message";
-import type { QuestionAnswerData } from "@/src/core/question-core";
+import type { QuestionAnswerData } from "@/src/core";
 
 /**
  * Static rendering of an answered question (tool part in `output-available`).

components/artifacts/demo-card.tsx

@@ -2,7 +2,7 @@
 
 import { useContext, useEffect, useMemo, useRef, useState } from "react";
 import { ChatActionsContext } from "@/components/chat";
-import type { ArtifactPartProps, DemoResult, JobRecord } from "@/src/core/contracts";
+import type { ArtifactPartProps, DemoResult, JobRecord } from "@/src/core";
 
 /**
  * Demo artifact card (W6): while the part is input-available, a job activity

components/artifacts/index.ts

@@ -1,5 +1,5 @@
 import type { ComponentType } from "react";
-import type { ArtifactPartProps } from "@/src/core/contracts";
+import type { ArtifactPartProps } from "@/src/core";
 import { DemoCard } from "@/components/artifacts/demo-card";
 import { JobCard } from "@/components/artifacts/job-card";
 import { PlanDivider } from "@/components/artifacts/plan-divider";

components/artifacts/job-card.tsx

@@ -3,7 +3,7 @@
 import { useContext, useEffect, useRef, useState } from "react";
 import { MessageResponse } from "@/components/ai-elements/message";
 import { ChatActionsContext } from "@/components/chat";
-import type { ArtifactPartProps, JobRecord, ResearchResult } from "@/src/core/contracts";
+import type { ArtifactPartProps, JobRecord, ResearchResult } from "@/src/core";
 
 /**
  * The research job card (contracts.ts "THE ASYNC PROTOCOL" §4).

components/artifacts/plan-divider.tsx

@@ -1,4 +1,4 @@
-import type { ArtifactPartProps, PlanToolResult } from "@/src/core/contracts";
+import type { ArtifactPartProps, PlanToolResult } from "@/src/core";
 
 /**
  * The probe→teach divider (vision §2 "Two phases, clearly separated").

components/artifacts/visual-card.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import type { ArtifactPartProps, VisualResult } from "@/src/core/contracts";
+import type { ArtifactPartProps, VisualResult } from "@/src/core";
 import { JobActivityCard } from "@/components/artifacts/demo-card";
 
 /**

components/chat.tsx

@@ -20,11 +20,8 @@ import { Composer } from "@/components/composer";
 import { QuestionDock } from "@/components/question-dock";
 import { SidebarToggle } from "@/components/sidebar";
 import { TreePanel } from "@/components/tree-panel";
-import type { TeacherUIMessage } from "@/src/agent/ui-message";
-import type { ArtifactPartProps } from "@/src/core/contracts";
-import type { QuestionAnswerData } from "@/src/core/question-core";
-import { findPendingJobCall, findPendingToolCall } from "@/src/core/pending";
-import { phaseAt } from "@/src/core/phases";
+import type { ArtifactPartProps, QuestionAnswerData, TeacherUIMessage } from "@/src/core";
+import { findPendingJobCall, findPendingToolCall, phaseAt } from "@/src/core";
 
 /** One width for everything: transcript, cards, and the bottom blob share this column. */
 const COLUMN = "mx-auto w-full max-w-3xl px-4";
@@ -101,7 +98,7 @@ export function Chat({
 		) {
 			void sendMessage();
 		}
-		// eslint-disable-next-line react-hooks/exhaustive-deps -- mount-only by design
+		// mount-only by design
 	}, []);
 
 	const pending = findPendingToolCall(messages);
@@ -318,7 +315,7 @@ function DockOverlay({
 			setExpanded(isAtBottom);
 			if (isAtBottom) void scrollToBottom();
 		}
-		// eslint-disable-next-line react-hooks/exhaustive-deps -- fire only when a NEW question lands
+		// fire only when a NEW question lands
 	}, [pendingId]);
 
 	// ── Collapse state machine with hysteresis ──

components/graph-view.tsx

@@ -20,9 +20,7 @@ import Link from "next/link";
 import { WaypointsIcon } from "lucide-react";
 import Graph from "graphology";
 import forceAtlas2 from "graphology-layout-forceatlas2";
-import type { GraphNode } from "@/src/core/contracts";
-import type { GraphSnapshot, NodeStateClass } from "@/src/core/graph";
-import { seededRandom } from "@/src/core/question-core";
+import { seededRandom, type GraphNode, type GraphSnapshot, type NodeStateClass } from "@/src/core";
 
 /** Per-state visuals: color token + node size (WebGL wants hex, not oklch). */
 const STATE_TOKENS: Record<NodeStateClass, { cssVar: string; size: number }> = {

components/question-dock.tsx

@@ -5,7 +5,6 @@ import { ArrowDownIcon, ChevronRightIcon, PlayIcon } from "lucide-react";
 import { Button } from "@/components/ui/button";
 import { MessageResponse } from "@/components/ai-elements/message";
 import { cn } from "@/lib/utils";
-import type { AskToolInput, QuizToolInput } from "@/src/agent/tools";
 import {
 	buildAnswer,
 	coerceCorrectAnswer,
@@ -14,10 +13,12 @@ import {
 	seededRandom,
 	shuffleOptions,
 	type AnswerRequest,
+	type AskToolInput,
 	type QuestionAnswerData,
 	type QuestionData,
 	type QuestionMode,
-} from "@/src/core/question-core";
+	type QuizToolInput,
+} from "@/src/core";
 
 /**
  * The question dock — a pending quiz/ask REPLACES the chat composer: the

components/sidebar.tsx

@@ -6,7 +6,7 @@ import { usePathname, useRouter } from "next/navigation";
 import { PanelLeftCloseIcon, PanelLeftOpenIcon } from "lucide-react";
 import { Button } from "@/components/ui/button";
 import { cn } from "@/lib/utils";
-import type { ChatSummary } from "@/src/store/chats";
+import type { ChatSummary } from "@/src/core";
 
 /**
  * Toggleable sidebar — NOT a modal drawer: no backdrop, no focus theft. It

components/tree-panel.tsx

@@ -3,12 +3,7 @@
 import { useEffect, useMemo, useState } from "react";
 import { CheckIcon, ChevronsRightIcon, ListTreeIcon } from "lucide-react";
 import { cn } from "@/lib/utils";
-import {
-	planNodeStatus,
-	type PlanNode,
-	type PlanNodeStatus,
-	type PlanTree,
-} from "@/src/core/contracts";
+import { planNodeStatus, type PlanNode, type PlanNodeStatus, type PlanTree } from "@/src/core";
 
 /**
 * The persistent plan-tree panel (vision §2 "Persistent tree view", W7).