feat(workspace,smart-scroll): per-conversation cwd + LSP view; smart auto-scroll

workspace ([email protected]): a cwd field in the Model sidebar view (GET/PUT /conversations/:id/cwd) + a new 'Language Servers' view (GET /conversations/:id/lsp) with per-server connected/starting/error badges, spinner, error text, and refresh. Store-owned reactive cwd, re-seeded on focus change; works for DRAFTS too (targets the draft's client-minted id, which survives promotion, so turn 1 runs in the chosen cwd). Network seam normalizes the untyped LSP body.

smart-scroll: pure stick-to-bottom reducer + injected controller shell (scroll/scrollend + a ResizeObserver on the content so the view follows async height changes — markdown/highlight, images, collapses, viewport reflow), plus a floating scroll-to-bottom button. FIX: restore the transcript scrollbar — the refactor moved overflow-y-auto to an inner child, so the flex-1 container needed min-h-0 to constrain instead of growing to content.

harness: vitest-setup polyfills Element.scrollTo + ResizeObserver (jsdom implements neither), fixing App component tests. docs: backend-handoff pruned (CR-3 resolved/removed); added cwd/LSP verification courier (backend confirmed all 6 asks ✅); removed the resolved cache-warming-timer courier.

Verified: svelte-check 0 errors, biome clean, 523 tests pass, vite build OK.

1 files changed, 103 insertions, 0 deletions

diff --git a/src/features/smart-scroll/logic/smart-scroll.test.ts b/src/features/smart-scroll/logic/smart-scroll.test.ts
new file mode 100644
index 0000000..fc3e3d1
--- /dev/null
+++ b/src/features/smart-scroll/logic/smart-scroll.test.ts
@@ -0,0 +1,103 @@
+import { describe, expect, it } from "vitest";
+import {
+	createSmartScrollState,
+	isNearBottom,
+	NEAR_BOTTOM_THRESHOLD,
+	onContentChange,
+	onReset,
+	onResume,
+	onScroll,
+	type ScrollGeometry,
+} from "./smart-scroll";
+
+// A viewport 100px tall over 1000px of content: scrollTop 900 == pinned to bottom.
+const atBottom: ScrollGeometry = { scrollTop: 900, scrollHeight: 1000, clientHeight: 100 };
+const nearBottom: ScrollGeometry = {
+	scrollTop: 900 - NEAR_BOTTOM_THRESHOLD,
+	scrollHeight: 1000,
+	clientHeight: 100,
+};
+const scrolledUp: ScrollGeometry = { scrollTop: 200, scrollHeight: 1000, clientHeight: 100 };
+
+describe("isNearBottom", () => {
+	it("is true exactly at the bottom", () => {
+		expect(isNearBottom(atBottom)).toBe(true);
+	});
+
+	it("is true within the threshold of the bottom", () => {
+		expect(isNearBottom(nearBottom)).toBe(true);
+	});
+
+	it("is false just beyond the threshold", () => {
+		expect(
+			isNearBottom({
+				scrollTop: 900 - NEAR_BOTTOM_THRESHOLD - 1,
+				scrollHeight: 1000,
+				clientHeight: 100,
+			}),
+		).toBe(false);
+	});
+
+	it("is false when scrolled well up", () => {
+		expect(isNearBottom(scrolledUp)).toBe(false);
+	});
+
+	it("honours a custom threshold", () => {
+		const geom: ScrollGeometry = { scrollTop: 800, scrollHeight: 1000, clientHeight: 100 };
+		expect(isNearBottom(geom, 50)).toBe(false);
+		expect(isNearBottom(geom, 150)).toBe(true);
+	});
+});
+
+describe("smart-scroll reducer", () => {
+	it("starts stuck and hides the button", () => {
+		const s = createSmartScrollState();
+		expect(s.stuck).toBe(true);
+	});
+
+	it("onScroll up unsticks and shows the button, with no command", () => {
+		const r = onScroll(createSmartScrollState(), scrolledUp);
+		expect(r.state.stuck).toBe(false);
+		expect(r.showButton).toBe(true);
+		expect(r.command).toBeNull();
+	});
+
+	it("onScroll back to the bottom re-sticks and hides the button", () => {
+		const up = onScroll(createSmartScrollState(), scrolledUp).state;
+		const r = onScroll(up, atBottom);
+		expect(r.state.stuck).toBe(true);
+		expect(r.showButton).toBe(false);
+		expect(r.command).toBeNull();
+	});
+
+	it("onContentChange while stuck emits a NON-animated scroll (keep up with the stream)", () => {
+		const r = onContentChange(createSmartScrollState(), atBottom);
+		expect(r.command).toEqual({ kind: "scroll-to-bottom", animate: false });
+		expect(r.state.stuck).toBe(true);
+	});
+
+	it("onContentChange while unstuck emits NO command (leave the reader in place)", () => {
+		const up = onScroll(createSmartScrollState(), scrolledUp).state;
+		const r = onContentChange(up, scrolledUp);
+		expect(r.command).toBeNull();
+		expect(r.state.stuck).toBe(false);
+		expect(r.showButton).toBe(true);
+	});
+
+	it("onResume re-sticks and emits an ANIMATED scroll", () => {
+		const up = onScroll(createSmartScrollState(), scrolledUp).state;
+		const r = onResume(up);
+		expect(r.state.stuck).toBe(true);
+		expect(r.showButton).toBe(false);
+		expect(r.command).toEqual({ kind: "scroll-to-bottom", animate: true });
+	});
+
+	it("onReset returns to stuck and snaps (non-animated) to the bottom", () => {
+		const up = onScroll(createSmartScrollState(), scrolledUp).state;
+		const r = onReset();
+		void up;
+		expect(r.state.stuck).toBe(true);
+		expect(r.command).toEqual({ kind: "scroll-to-bottom", animate: false });
+		expect(r.showButton).toBe(false);
+	});
+});