feat(cache-warming,surfaces,metrics,markdown): conversation-scoped surfaces, cache warming + retention, markdown

Consumes the backend cache-warming + cache-rate handoffs end-to-end and adds supporting infra:

- protocol/transport: conversation-scoped surfaces (conversationId on subscribe/invoke/surface + staleness routing); store auto-subscribes the catalog with the focused conversation and re-scopes on switch.
- surface-host: generic Number field renderer + custom rendererId dispatch (graceful skip on unknown).
- cache-warming feature: enabled toggle, min+sec interval, AUTHORITATIVE countdown from the surface's cache-warming-timer nextWarmAt, manual Warm now (POST /chat/warm), lastWarmAt-keyed history, cache-retention stat, expectedCacheRate headline.
- metrics: cross-turn expected-cache (retention) derivation + bubble badge; cache-rate fix needs no code change (inputTokens now total).
- markdown feature: marked + marked-highlight + highlight.js + dompurify, rendered in ChatView.
- fixes (gemini review): {#key activeConversationId} remount of CacheWarmingView to stop history/feedback leaking across tabs; guard NaN interval inputs from committing 0.
- docs/contracts: regenerated transport/ui-contract mirrors; backend-handoff updated (CR-3 resolved).

Verified: svelte-check 0 errors, biome clean, 494 tests pass, vite build OK.

1 files changed, 220 insertions, 0 deletions

diff --git a/src/features/cache-warming/logic/view-model.test.ts b/src/features/cache-warming/logic/view-model.test.ts
new file mode 100644
index 0000000..3d6f6d0
--- /dev/null
+++ b/src/features/cache-warming/logic/view-model.test.ts
@@ -0,0 +1,220 @@
+import type { SurfaceSpec } from "@dispatch/ui-contract";
+import { describe, expect, it } from "vitest";
+import {
+	clampMinutes,
+	clampSeconds,
+	colorClass,
+	formatCountdown,
+	formatWarmLabel,
+	fromMinSec,
+	initialWarmingState,
+	observeWarm,
+	parseControls,
+	parsePct,
+	secondsUntilNext,
+	statusForPct,
+	toMinSec,
+} from "./view-model";
+
+const spec = (fields: SurfaceSpec["fields"]): SurfaceSpec => ({
+	id: "cache-warming",
+	region: "side",
+	title: "Cache Warming",
+	fields,
+});
+
+describe("parsePct", () => {
+	it("parses a percentage string", () => {
+		expect(parsePct("100%")).toBe(100);
+		expect(parsePct("93 %")).toBe(93);
+		expect(parsePct("0%")).toBe(0);
+	});
+	it("returns null for a dash / non-numeric", () => {
+		expect(parsePct("—")).toBeNull();
+		expect(parsePct("n/a")).toBeNull();
+	});
+});
+
+describe("parseControls", () => {
+	it("returns empty defaults for a null spec", () => {
+		const c = parseControls(null);
+		expect(c).toEqual({
+			enabled: false,
+			toggleActionId: null,
+			intervalSeconds: 0,
+			setIntervalActionId: null,
+			lastPct: null,
+			retentionPct: null,
+			nextWarmAt: null,
+			lastWarmAt: null,
+		});
+	});
+
+	it("extracts toggle / number / both stats / timer by kind", () => {
+		const c = parseControls(
+			spec([
+				{
+					kind: "toggle",
+					label: "Enabled",
+					value: true,
+					action: { actionId: "cache-warming/toggle" },
+				},
+				{
+					kind: "number",
+					label: "Interval",
+					value: 240,
+					unit: "s",
+					action: { actionId: "cache-warming/set-interval" },
+				},
+				{ kind: "stat", label: "Last cache rate", value: "61%" },
+				{ kind: "stat", label: "Cache retention", value: "100%" },
+				{
+					kind: "custom",
+					rendererId: "cache-warming-timer",
+					payload: { nextWarmAt: 1_700_000_240_000, lastWarmAt: 1_700_000_000_000 },
+				},
+			]),
+		);
+		expect(c).toEqual({
+			enabled: true,
+			toggleActionId: "cache-warming/toggle",
+			intervalSeconds: 240,
+			setIntervalActionId: "cache-warming/set-interval",
+			lastPct: 61,
+			retentionPct: 100,
+			nextWarmAt: 1_700_000_240_000,
+			lastWarmAt: 1_700_000_000_000,
+		});
+	});
+
+	it("tells the retention stat apart from the rate stat by label", () => {
+		const c = parseControls(
+			spec([
+				{ kind: "stat", label: "Cache retention", value: "100%" },
+				{ kind: "stat", label: "Last cache rate", value: "61%" },
+			]),
+		);
+		expect(c.retentionPct).toBe(100);
+		expect(c.lastPct).toBe(61);
+	});
+
+	it("treats a '—' stat as no pct", () => {
+		const c = parseControls(spec([{ kind: "stat", label: "Last cache rate", value: "—" }]));
+		expect(c.lastPct).toBeNull();
+	});
+
+	it("ignores an unknown custom renderer and a malformed timer payload", () => {
+		const c = parseControls(
+			spec([
+				{ kind: "custom", rendererId: "something-else", payload: { nextWarmAt: 5 } },
+				{ kind: "custom", rendererId: "cache-warming-timer", payload: "nope" },
+			]),
+		);
+		expect(c.nextWarmAt).toBeNull();
+		expect(c.lastWarmAt).toBeNull();
+	});
+});
+
+describe("interval ↔ min/sec", () => {
+	it("clampSeconds caps at 0..59", () => {
+		expect(clampSeconds(75)).toBe(59);
+		expect(clampSeconds(-3)).toBe(0);
+		expect(clampSeconds(30)).toBe(30);
+		expect(clampSeconds(Number.NaN)).toBe(0);
+	});
+	it("clampMinutes floors at 0", () => {
+		expect(clampMinutes(-1)).toBe(0);
+		expect(clampMinutes(4)).toBe(4);
+	});
+	it("toMinSec splits total seconds", () => {
+		expect(toMinSec(240)).toEqual({ minutes: 4, seconds: 0 });
+		expect(toMinSec(125)).toEqual({ minutes: 2, seconds: 5 });
+		expect(toMinSec(45)).toEqual({ minutes: 0, seconds: 45 });
+	});
+	it("fromMinSec combines (clamping seconds to 59)", () => {
+		expect(fromMinSec(4, 0)).toBe(240);
+		expect(fromMinSec(2, 5)).toBe(125);
+		expect(fromMinSec(1, 75)).toBe(119); // 75s clamped to 59
+	});
+});
+
+describe("status + formatting", () => {
+	it("statusForPct buckets high/mid/low", () => {
+		expect(statusForPct(100)).toBe("success");
+		expect(statusForPct(80)).toBe("success");
+		expect(statusForPct(60)).toBe("warning");
+		expect(statusForPct(40)).toBe("warning");
+		expect(statusForPct(10)).toBe("error");
+	});
+	it("colorClass maps to literal DaisyUI classes", () => {
+		expect(colorClass("success")).toBe("text-success");
+		expect(colorClass("warning")).toBe("text-warning");
+		expect(colorClass("error")).toBe("text-error");
+	});
+	it("formatWarmLabel matches the manual-warm phrasing", () => {
+		expect(formatWarmLabel(100)).toBe("Warmed — 100% cache hit");
+		expect(formatWarmLabel(92.6)).toBe("Warmed — 93% cache hit");
+	});
+	it("formatCountdown renders s and m:ss", () => {
+		expect(formatCountdown(9)).toBe("9s");
+		expect(formatCountdown(59)).toBe("59s");
+		expect(formatCountdown(60)).toBe("1:00");
+		expect(formatCountdown(185)).toBe("3:05");
+		expect(formatCountdown(-5)).toBe("0s");
+	});
+});
+
+describe("warming history reducer (observeWarm)", () => {
+	it("starts empty", () => {
+		const s = initialWarmingState();
+		expect(s.history).toEqual([]);
+		expect(s.lastWarmAt).toBeNull();
+	});
+
+	it("records a new entry on each new authoritative lastWarmAt", () => {
+		let s = initialWarmingState();
+		s = observeWarm(s, 1000, 100);
+		s = observeWarm(s, 2000, 90);
+		expect(s.history).toEqual([
+			{ pct: 90, at: 2000 },
+			{ pct: 100, at: 1000 },
+		]);
+		expect(s.lastWarmAt).toBe(2000);
+	});
+
+	it("de-duplicates on the timestamp, not the pct (a re-pushed surface → no dup)", () => {
+		let s = initialWarmingState();
+		s = observeWarm(s, 1000, 100); // warm
+		s = observeWarm(s, 1000, 100); // toggle/interval re-push, same lastWarmAt → skip
+		expect(s.history).toHaveLength(1);
+	});
+
+	it("records two warms with the SAME pct (distinct timestamps both count)", () => {
+		let s = initialWarmingState();
+		s = observeWarm(s, 1000, 100);
+		s = observeWarm(s, 2000, 100);
+		expect(s.history.map((e) => e.at)).toEqual([2000, 1000]);
+	});
+
+	it("ignores a null lastWarmAt; a null pct advances the key without an entry", () => {
+		let s = initialWarmingState();
+		s = observeWarm(s, null, 100);
+		expect(s.history).toEqual([]);
+		s = observeWarm(s, 1000, null);
+		expect(s.history).toEqual([]);
+		expect(s.lastWarmAt).toBe(1000);
+	});
+});
+
+describe("secondsUntilNext (authoritative, from nextWarmAt)", () => {
+	it("is null when nothing is scheduled (nextWarmAt null)", () => {
+		expect(secondsUntilNext(null, 5000)).toBeNull();
+	});
+
+	it("counts down to nextWarmAt, floored at 0", () => {
+		expect(secondsUntilNext(10_000, 10_000)).toBe(0);
+		expect(secondsUntilNext(250_000, 10_000)).toBe(240);
+		expect(secondsUntilNext(70_000, 10_000)).toBe(60);
+		expect(secondsUntilNext(5_000, 999_999)).toBe(0); // already past
+	});
+});