feat: key usage panel — display usage data for Claude, OpenCode, and Copilot

Adds 'Key Usage' to the sidebar dropdown with per-provider live usage:
- Claude: 5-hour and weekly utilization bars with reset timestamps
  (normalizes Anthropic's 0-100% API response to 0-1 internally)
- OpenCode: Scrapes usage from workspace page via OPENCODE_COOKIE
  session cookie, mapping key IDs to OPENCODE_WS1_ID/OPENCODE_WS2_ID
- Copilot: Fetches from api.github.com/copilot_internal/user with
  entitlement/remaining/quota reset tracking

New files: opencode.ts, copilot.ts (usage fetchers), KeyUsage.svelte
New route: GET /models/key-usage?keyId=X dispatches by provider

4 files changed, 215 insertions, 11 deletions

diff --git a/packages/core/src/credentials/claude.ts b/packages/core/src/credentials/claude.ts
index 87568e6..cc6daec 100644
--- a/packages/core/src/credentials/claude.ts
+++ b/packages/core/src/credentials/claude.ts
@@ -429,7 +429,9 @@ async function fetchClaudeUsage(accessToken: string): Promise<ClaudeUsageReport
 		const parseBucket = (bucket: unknown): ClaudeUsageBucket | undefined => {
 			if (!bucket || typeof bucket !== "object" || Array.isArray(bucket)) return undefined;
 			const b = bucket as Record<string, unknown>;
-			const utilization = typeof b.utilization === "number" ? b.utilization : undefined;
+			// API returns utilization as 0-100 percentage; normalize to 0-1 fraction
+			const rawUtil = typeof b.utilization === "number" ? b.utilization : undefined;
+			const utilization = rawUtil !== undefined ? rawUtil / 100 : undefined;
 			const resetsAt = typeof b.resets_at === "string" ? Date.parse(b.resets_at as string) : undefined;
 			if (utilization === undefined && resetsAt === undefined) return undefined;
 			return { utilization, resetsAt };
diff --git a/packages/core/src/credentials/copilot.ts b/packages/core/src/credentials/copilot.ts
new file mode 100644
index 0000000..8baf6f4
--- /dev/null
+++ b/packages/core/src/credentials/copilot.ts
@@ -0,0 +1,64 @@
+// ─── GitHub Copilot Usage Tracking ───────────────────────────
+// Uses the internal GitHub Copilot user endpoint (same one the
+// official VS Code Copilot extension calls).
+
+export interface CopilotUsageReport {
+	tokensConsumed?: number;
+	tokensRemaining?: number;
+	percentUsed?: number; // 0-100
+	resetAt?: number; // Unix timestamp ms
+	plan?: string;
+}
+
+export async function fetchCopilotUsage(
+	token: string,
+	_baseUrl: string,
+): Promise<CopilotUsageReport | null> {
+	const url = "https://api.github.com/copilot_internal/user";
+	const headers: Record<string, string> = {
+		authorization: `Bearer ${token}`,
+		accept: "application/json",
+	};
+
+	try {
+		const response = await fetch(url, { headers });
+		if (!response.ok) return null;
+
+		const data = (await response.json()) as Record<string, unknown>;
+		const plan = typeof data.copilot_plan === "string" ? data.copilot_plan : undefined;
+
+		const resetDate = typeof data.quota_reset_date === "string" ? data.quota_reset_date : undefined;
+		const resetAt = resetDate ? Date.parse(resetDate) : undefined;
+
+		const qs = data.quota_snapshots as Record<string, unknown> | undefined;
+		const pi = qs?.premium_interactions as Record<string, unknown> | undefined;
+
+		const entitlement = typeof pi?.entitlement === "number" ? pi.entitlement : undefined;
+		const remaining = typeof pi?.remaining === "number" ? pi.remaining : undefined;
+		const percentRemaining =
+			typeof pi?.percent_remaining === "number" ? pi.percent_remaining : undefined;
+
+		if (entitlement === undefined && remaining === undefined) {
+			return null;
+		}
+
+		const tokensConsumed =
+			entitlement !== undefined && remaining !== undefined ? entitlement - remaining : undefined;
+		const percentUsed =
+			percentRemaining !== undefined
+				? Math.round((100 - percentRemaining) * 100) / 100
+				: tokensConsumed !== undefined && entitlement !== undefined && entitlement > 0
+					? Math.round((tokensConsumed / entitlement) * 10000) / 100
+					: undefined;
+
+		return {
+			tokensConsumed,
+			tokensRemaining: remaining,
+			percentUsed,
+			resetAt: resetAt && !Number.isNaN(resetAt) ? resetAt : undefined,
+			plan,
+		};
+	} catch {
+		return null;
+	}
+}
diff --git a/packages/core/src/credentials/index.ts b/packages/core/src/credentials/index.ts
index d72ad48..0ae4edb 100644
--- a/packages/core/src/credentials/index.ts
+++ b/packages/core/src/credentials/index.ts
@@ -1,18 +1,27 @@
 export {
-	type ClaudeCredentials,
+	ANTHROPIC_MODELS_FALLBACK,
+	buildBillingHeaderValue,
 	type ClaudeAccount,
+	type ClaudeCredentials,
+	type ClaudeProfile,
 	type ClaudeUsageBucket,
 	type ClaudeUsageReport,
-	type ClaudeProfile,
-	ANTHROPIC_MODELS_FALLBACK,
-	fetchAnthropicModels,
 	discoverClaudeAccounts,
-	refreshAccountCredentials,
-	refreshAccountCredentialsAsync,
-	validateAccountCredentials,
-	buildBillingHeaderValue,
+	fetchAnthropicModels,
+	getAccountUsage,
 	getAnthropicBetas,
 	getAnthropicHeaders,
-	getAccountUsage,
+	refreshAccountCredentials,
+	refreshAccountCredentialsAsync,
 	SYSTEM_IDENTITY,
-} from "./claude.js";
\ No newline at end of file
+	validateAccountCredentials,
+} from "./claude.js";
+export {
+	type CopilotUsageReport,
+	fetchCopilotUsage,
+} from "./copilot.js";
+export {
+	fetchOpencodeUsage,
+	type OpencodeUsageBucket,
+	type OpencodeUsageReport,
+} from "./opencode.js";
diff --git a/packages/core/src/credentials/opencode.ts b/packages/core/src/credentials/opencode.ts
new file mode 100644
index 0000000..7a74486
--- /dev/null
+++ b/packages/core/src/credentials/opencode.ts
@@ -0,0 +1,129 @@
+// ─── OpenCode Usage Tracking ──────────────────────────────────
+// OpenCode has no public usage API. We scrape usage from the
+// SolidStart SSR-rendered workspace page using a session cookie.
+// Requires OPENCODE_COOKIE env var.
+// Workspace IDs: OPENCODE_WS1_ID for opencode-1, OPENCODE_WS2_ID for opencode-2.
+
+export interface OpencodeUsageBucket {
+	utilization?: number; // 0-1 fraction
+	resetsAt?: number; // Unix timestamp ms
+}
+
+export interface OpencodeUsageReport {
+	fiveHour?: OpencodeUsageBucket;
+	weekly?: OpencodeUsageBucket;
+	monthly?: OpencodeUsageBucket;
+}
+
+function getWorkspaceId(keyId: string): string | undefined {
+	// Match ai-usage convention: opencode-1 → OPENCODE_WS1_ID, opencode-2 → OPENCODE_WS2_ID
+	const match = keyId.match(/opencode-(\d+)$/i);
+	if (match) {
+		const num = match[1];
+		const specific = process.env[`OPENCODE_WS${num}_ID`];
+		if (specific) return specific;
+	}
+	return process.env.OPENCODE_WS_ID;
+}
+
+function parseOcDouble(html: string, key: string): number {
+	const idx = html.indexOf(`${key}:`);
+	if (idx === -1) return 0;
+	let start = idx + key.length + 1;
+	while (start < html.length && html[start] === " ") start++;
+	let end = start;
+	while (end < html.length && html[end] !== "," && html[end] !== "}") {
+		end++;
+	}
+	const val = parseFloat(html.slice(start, end));
+	return Number.isNaN(val) ? 0 : val;
+}
+
+function parseOcInt(html: string, key: string): number {
+	const idx = html.indexOf(`${key}:`);
+	if (idx === -1) return 0;
+	let i = idx + key.length + 1;
+	while (i < html.length && html[i] === " ") i++;
+	return parseInt(html.slice(i), 10) || 0;
+}
+
+function parseOcBucket(
+	html: string,
+	bucketName: string,
+): { utilization: number; resetsAt: number } | null {
+	const search = `${bucketName}:`;
+	const pos = html.indexOf(search);
+	if (pos === -1) return null;
+
+	// Find the opening brace after the bucket name
+	const brace = html.indexOf("{", pos);
+	if (brace === -1) return null;
+
+	const resetSecs = parseOcInt(html.slice(brace), "resetInSec");
+	const usagePct = parseOcDouble(html.slice(brace), "usagePercent");
+
+	const utilization = usagePct / 100; // convert 0-100% to 0-1 fraction
+	const resetsAt = Date.now() + resetSecs * 1000;
+
+	return { utilization, resetsAt };
+}
+
+export async function fetchOpencodeUsage(
+	keyId: string,
+): Promise<OpencodeUsageReport | null> {
+	const cookie = process.env.OPENCODE_COOKIE;
+	const wsId = getWorkspaceId(keyId);
+
+	if (!cookie || !wsId) {
+		return null;
+	}
+
+	const url = `https://opencode.ai/workspace/${encodeURIComponent(wsId)}/go`;
+
+	try {
+		const response = await fetch(url, {
+			headers: {
+				accept: "text/html",
+				cookie: `auth=${cookie}`,
+			},
+			redirect: "follow",
+		});
+
+		if (!response.ok) return null;
+
+		const html = await response.text();
+
+		// Auth redirect check
+		if (
+			html.includes("/auth/authorize") ||
+			html.includes('window.location="/auth/authorize"')
+		) {
+			return null;
+		}
+
+		// Find the lite.subscription data block.
+		// HTML contains: lite.subscription.get[\"<wsId>\"]
+		// We need literal backslashes; use \x5c (hex for backslash).
+		const wsKey = `lite.subscription.get[\x5c"${wsId}\x5c"]`;
+		const wsPos = html.indexOf(wsKey);
+		if (wsPos === -1) return null;
+
+		// Search for the resolved data starting from the ws key position
+		const minePos = html.indexOf("mine:", wsPos);
+		const slice = minePos !== -1 ? html.slice(minePos) : "";
+
+		const fiveHour = parseOcBucket(slice, "rollingUsage");
+		const weekly = parseOcBucket(slice, "weeklyUsage");
+		const monthly = parseOcBucket(slice, "monthlyUsage");
+
+		if (!fiveHour && !weekly && !monthly) return null;
+
+		return {
+			fiveHour: fiveHour ?? undefined,
+			weekly: weekly ?? undefined,
+			monthly: monthly ?? undefined,
+		};
+	} catch {
+		return null;
+	}
+}