diff --git a/open-sse/services/usage.ts b/open-sse/services/usage.ts
index 1f3cade0f6..9d85d18cb5 100644
--- a/open-sse/services/usage.ts
+++ b/open-sse/services/usage.ts
@@ -2917,4 +2917,17 @@ export const __testing = {
   getMiniMaxPlanLabel,
   inferMiniMaxPlanLabelFromTotals,
   getOpencodeUsage,
+  getClaudePlanLabel,
+  createQuotaFromUsage,
+  getMiniMaxQuotaResetAt,
+  isMiniMaxTextQuotaModel,
+  getMiniMaxSessionTotal,
+  getMiniMaxWeeklyTotal,
+  createMiniMaxQuotaFromCount,
+  getMiniMaxAuthErrorMessage,
+  getMiniMaxErrorSummary,
+  mapCodeAssistSubscriptionToPlanLabel,
+  mapCodeAssistTierIdToLabel,
+  mapSubscriptionTierStringToPlanLabel,
+  toDisplayLabel,
 };
diff --git a/tests/unit/usage-utils.test.ts b/tests/unit/usage-utils.test.ts
new file mode 100644
index 0000000000..8d3a99c018
--- /dev/null
+++ b/tests/unit/usage-utils.test.ts
@@ -0,0 +1,447 @@
+/**
+ * Tests for pure utility functions exported via usage.__testing
+ *
+ * Covers: parseResetTime, formatGitHubQuotaSnapshot, inferGitHubPlanName,
+ *         getMiniMaxPlanLabel, inferMiniMaxPlanLabelFromTotals,
+ *         extractCodeAssistSubscriptionTier, extractCodeAssistOnboardTierId.
+ *
+ * These are pure functions (no fetch, no DB) — run without DATA_DIR override.
+ */
+
+import { describe, it } from "node:test";
+import assert from "node:assert/strict";
+
+process.env.NODE_ENV = "test";
+
+const usage = await import("../../open-sse/services/usage.ts");
+const { __testing } = usage;
+
+/* ------------------------------------------------------------------ */
+/*  parseResetTime                                                     */
+/* ------------------------------------------------------------------ */
+describe("parseResetTime", () => {
+  it("returns null for null / undefined", () => {
+    assert.equal(__testing.parseResetTime(null), null);
+    assert.equal(__testing.parseResetTime(undefined), null);
+  });
+
+  it("returns null for epoch-zero", () => {
+    assert.equal(__testing.parseResetTime(0), null);
+    assert.equal(__testing.parseResetTime("1970-01-01T00:00:00.000Z"), null);
+  });
+
+  it("parses a number as ms timestamp (value > 1e12)", () => {
+    const ms = 1_700_000_000_000;
+    const out = __testing.parseResetTime(ms);
+    assert.equal(out, new Date(ms).toISOString());
+  });
+
+  it("parses a number as seconds (value < 1e12)", () => {
+    const sec = 1_700_000_000; // < 1e12
+    const out = __testing.parseResetTime(sec);
+    assert.equal(out, new Date(sec * 1000).toISOString());
+  });
+
+  it("parses an ISO date string", () => {
+    const iso = "2026-06-15T12:00:00.000Z";
+    assert.equal(__testing.parseResetTime(iso), new Date(iso).toISOString());
+  });
+
+  it("parses a Date object", () => {
+    const d = new Date("2026-07-01T00:00:00Z");
+    assert.equal(__testing.parseResetTime(d), d.toISOString());
+  });
+
+  it("returns null for non-date values (objects, booleans)", () => {
+    assert.equal(__testing.parseResetTime({}), null);
+    assert.equal(__testing.parseResetTime(true), null);
+  });
+
+  it("returns null for invalid date strings", () => {
+    assert.equal(__testing.parseResetTime("not-a-date"), null);
+  });
+});
+
+/* ------------------------------------------------------------------ */
+/*  formatGitHubQuotaSnapshot                                          */
+/* ------------------------------------------------------------------ */
+describe("formatGitHubQuotaSnapshot", () => {
+  it("returns null for empty object", () => {
+    assert.equal(__testing.formatGitHubQuotaSnapshot({}), null);
+  });
+
+  it("builds quota from snapshot with all fields", () => {
+    const snap = {
+      entitlement: 1000,
+      used: 300,
+      remaining: 700,
+      percent_remaining: 70,
+    };
+    const q = __testing.formatGitHubQuotaSnapshot(snap, "2026-07-01T00:00:00.000Z");
+    assert.equal(q.total, 1000);
+    assert.equal(q.used, 300);
+    assert.equal(q.remaining, 700);
+    assert.equal(q.remainingPercentage, 70);
+    assert.equal(q.resetAt, "2026-07-01T00:00:00.000Z");
+    assert.equal(q.unlimited, false);
+  });
+
+  it("uses entitlement when total is missing", () => {
+    const snap = { entitlement: 500, remaining: 0.5, percent_remaining: 50 };
+    const q = __testing.formatGitHubQuotaSnapshot(snap);
+    assert.equal(q.total, 500);
+    assert.ok(q.remaining !== undefined);
+  });
+
+  it("detects unlimited plan", () => {
+    const snap = { entitlement: 0, total: 0, unlimited: true };
+    const q = __testing.formatGitHubQuotaSnapshot(snap);
+    assert.equal(q.unlimited, true);
+    assert.equal(q.total, 0); // total is 0 when percent_remaining is missing
+  });
+
+  it("clamps negative values to 0", () => {
+    const snap = { used: -10, entitlement: 100, remaining: -5, percent_remaining: -1 };
+    const q = __testing.formatGitHubQuotaSnapshot(snap);
+    assert.equal(q.used, 0);
+    assert.equal(q.remaining, 0);
+    assert.equal(q.remainingPercentage, 0);
+  });
+
+  it("computes missing used from total - remaining", () => {
+    const snap = { entitlement: 200, remaining: 50 };
+    const q = __testing.formatGitHubQuotaSnapshot(snap);
+    assert.equal(q.used, 150); // 200 - 50
+  });
+
+  it("computes missing remaining from total - used", () => {
+    const snap = { used: 30, entitlement: 100 };
+    const q = __testing.formatGitHubQuotaSnapshot(snap);
+    assert.equal(q.remaining, 70);
+  });
+});
+
+/* ------------------------------------------------------------------ */
+/*  inferGitHubPlanName                                                */
+/* ------------------------------------------------------------------ */
+describe("inferGitHubPlanName", () => {
+  it("detects Copilot Pro+ from combined string", () => {
+    const data = { copilot_plan: "PRO_PLUS" };
+    assert.equal(__testing.inferGitHubPlanName(data, null), "Copilot Pro+");
+  });
+
+  it("detects Copilot Enterprise", () => {
+    const data = { copilot_plan: "ENTERPRISE" };
+    assert.equal(__testing.inferGitHubPlanName(data, null), "Copilot Enterprise");
+  });
+
+  it("detects Copilot Business", () => {
+    const data = { copilot_plan: "BUSINESS" };
+    assert.equal(__testing.inferGitHubPlanName(data, null), "Copilot Business");
+  });
+
+  it("detects Copilot Student", () => {
+    const data = { copilot_plan: "STUDENT" };
+    assert.equal(__testing.inferGitHubPlanName(data, null), "Copilot Student");
+  });
+
+  it("detects Copilot Free", () => {
+    const data = { copilot_plan: "FREE" };
+    assert.equal(__testing.inferGitHubPlanName(data, null), "Copilot Free");
+  });
+
+  it("detects Copilot Pro", () => {
+    const data = { copilot_plan: "PRO" };
+    assert.equal(__testing.inferGitHubPlanName(data, null), "Copilot Pro");
+  });
+
+  it("infers Pro+ from premiumTotal >= 1400", () => {
+    const data = { copilot_plan: "INDIVIDUAL" };
+    const premium = { used: 0, total: 1500, remaining: 1500, remainingPercentage: 100, unlimited: false };
+    assert.equal(__testing.inferGitHubPlanName(data, premium), "Copilot Pro+");
+  });
+
+  it("infers Enterprise from premiumTotal >= 900", () => {
+    const data = { copilot_plan: "INDIVIDUAL" };
+    const premium = { used: 0, total: 900, remaining: 900, remainingPercentage: 100, unlimited: false };
+    assert.equal(__testing.inferGitHubPlanName(data, premium), "Copilot Enterprise");
+  });
+
+  it("infers Pro when premiumTotal >= 250 and combined has INDIVIDUAL", () => {
+    const data = { copilot_plan: "INDIVIDUAL" };
+    const premium = { used: 0, total: 300, remaining: 300, remainingPercentage: 100, unlimited: false };
+    assert.equal(__testing.inferGitHubPlanName(data, premium), "Copilot Pro");
+  });
+
+  it("returns 'GitHub Copilot' fallback when nothing matches", () => {
+    const data = {};
+    assert.equal(__testing.inferGitHubPlanName(data, null), "GitHub Copilot");
+  });
+
+  it("falls back to sku label when planText is empty", () => {
+    const data = { access_type_sku: "BUSINESS_SPO" };
+    // "BUSINESS_SPO" upper-cased matches "BUSINESS" check first
+    assert.equal(__testing.inferGitHubPlanName(data, null), "Copilot Business");
+  });
+});
+
+/* ------------------------------------------------------------------ */
+/*  getMiniMaxPlanLabel                                                */
+/* ------------------------------------------------------------------ */
+describe("getMiniMaxPlanLabel", () => {
+  it("returns cleaned title from payload", () => {
+    const payload = { current_subscribe_title: "MiniMax Coding Plan Pro" };
+    assert.equal(__testing.getMiniMaxPlanLabel(payload), "Pro");
+  });
+
+  it("removes 'minimax ' prefix and 'coding plan' text", () => {
+    const payload = { plan: "MiniMax Coding Plan Ultra" };
+    assert.equal(__testing.getMiniMaxPlanLabel(payload), "Ultra");
+  });
+
+  it("calls inferMiniMaxPlanLabelFromTotals when no title present", () => {
+    const models = [{ current_interval_total_count: 500, current_weekly_total_count: 200 }];
+    const label = __testing.getMiniMaxPlanLabel({}, models);
+    assert.ok(typeof label === "string");
+    assert.ok(label.length > 0);
+  });
+
+  it("returns 'Coding Plan' fallback when nothing matches", () => {
+    assert.equal(__testing.getMiniMaxPlanLabel({}), "Coding Plan");
+  });
+
+  it("picks first non-empty string from multiple candidate fields", () => {
+    const payload = { combo_title: "", plan_name: "MiniMax Turbo", plan: "" };
+    const label = __testing.getMiniMaxPlanLabel(payload);
+    assert.equal(label, "Turbo");
+  });
+});
+
+/* ------------------------------------------------------------------ */
+/*  inferMiniMaxPlanLabelFromTotals                                    */
+/* ------------------------------------------------------------------ */
+describe("inferMiniMaxPlanLabelFromTotals", () => {
+  it("returns 'Max' for totals >= 15K", () => {
+    const models = [{ current_interval_total_count: 20_000 }];
+    assert.equal(__testing.inferMiniMaxPlanLabelFromTotals(models), "Max");
+  });
+
+  it("returns 'Plus' for totals >= 4.5K but < 15K", () => {
+    const models = [{ current_interval_total_count: 5_000 }];
+    assert.equal(__testing.inferMiniMaxPlanLabelFromTotals(models), "Plus");
+  });
+
+  it("returns 'Starter' for totals >= 1.5K but < 4.5K", () => {
+    const models = [{ current_interval_total_count: 2_000 }];
+    assert.equal(__testing.inferMiniMaxPlanLabelFromTotals(models), "Starter");
+  });
+
+  it("returns null when models array is empty", () => {
+    assert.equal(__testing.inferMiniMaxPlanLabelFromTotals([]), null);
+  });
+});
+
+/* ------------------------------------------------------------------ */
+/*  getMiniMaxQuotaResetAt                                             */
+/* ------------------------------------------------------------------ */
+describe("getMiniMaxQuotaResetAt", () => {
+  it("computes resetAt from remainsMs", () => {
+    const model = { remains_time: 3600_000 }; // 1 hour in ms
+    const capturedAt = 1_700_000_000_000;
+    const result = __testing.getMiniMaxQuotaResetAt(model, capturedAt, "remains_time", "remainsTime", "end_time", "endTime");
+    assert.equal(result, new Date(capturedAt + 3600_000).toISOString());
+  });
+
+  it("falls back to endTime when remainsMs is 0", () => {
+    const model = { end_time: 1_800_000_000_000 };
+    const capturedAt = 1_700_000_000_000;
+    const result = __testing.getMiniMaxQuotaResetAt(model, capturedAt, "remains_time", "remainsTime", "end_time", "endTime");
+    assert.equal(result, new Date(1_800_000_000_000).toISOString());
+  });
+});
+
+/* ------------------------------------------------------------------ */
+/*  getMiniMaxSessionTotal / getMiniMaxWeeklyTotal                     */
+/* ------------------------------------------------------------------ */
+describe("getMiniMaxSessionTotal", () => {
+  it("returns current_interval_total_count", () => {
+    assert.equal(__testing.getMiniMaxSessionTotal({ current_interval_total_count: 999 }), 999);
+  });
+
+  it("clamps to 0 for negative", () => {
+    assert.equal(__testing.getMiniMaxSessionTotal({ current_interval_total_count: -5 }), 0);
+  });
+});
+
+describe("getMiniMaxWeeklyTotal", () => {
+  it("returns current_weekly_total_count", () => {
+    assert.equal(__testing.getMiniMaxWeeklyTotal({ current_weekly_total_count: 500 }), 500);
+  });
+
+  it("clamps to 0 for negative", () => {
+    assert.equal(__testing.getMiniMaxWeeklyTotal({ current_weekly_total_count: -1 }), 0);
+  });
+});
+
+/* ------------------------------------------------------------------ */
+/*  createMiniMaxQuotaFromCount                                        */
+/* ------------------------------------------------------------------ */
+describe("createMiniMaxQuotaFromCount", () => {
+  it("computes used = total - count when countMeansRemaining", () => {
+    const q = __testing.createMiniMaxQuotaFromCount(100, 30, null, true);
+    assert.equal(q.used, 70);
+    assert.equal(q.remaining, 30);
+  });
+
+  it("treats count as used when countMeansRemaining is false", () => {
+    const q = __testing.createMiniMaxQuotaFromCount(100, 30, null, false);
+    assert.equal(q.used, 30);
+    assert.equal(q.remaining, 70);
+  });
+});
+
+/* ------------------------------------------------------------------ */
+/*  createQuotaFromUsage                                               */
+/* ------------------------------------------------------------------ */
+describe("createQuotaFromUsage", () => {
+  it("builds UsageQuota with correct math", () => {
+    const q = __testing.createQuotaFromUsage(200, 1000, "2026-07-01T00:00:00.000Z");
+    assert.equal(q.used, 200);
+    assert.equal(q.total, 1000);
+    assert.equal(q.remaining, 800);
+    assert.equal(q.remainingPercentage, 80);
+    assert.equal(q.resetAt, "2026-07-01T00:00:00.000Z");
+    assert.equal(q.unlimited, false);
+  });
+
+  it("clamps used to total", () => {
+    const q = __testing.createQuotaFromUsage(9999, 100, null);
+    assert.equal(q.used, 100);
+    assert.equal(q.remaining, 0);
+    assert.equal(q.remainingPercentage, 0);
+  });
+});
+
+/* ------------------------------------------------------------------ */
+/*  isMiniMaxTextQuotaModel                                            */
+/* ------------------------------------------------------------------ */
+describe("isMiniMaxTextQuotaModel", () => {
+  it("returns true for minimax-m prefixed models", () => {
+    assert.equal(__testing.isMiniMaxTextQuotaModel("minimax-m1"), true);
+    assert.equal(__testing.isMiniMaxTextQuotaModel("Minimax-M2.5"), true);
+  });
+
+  it("returns true for coding-plan prefixed models", () => {
+    assert.equal(__testing.isMiniMaxTextQuotaModel("Coding-Plan-1"), true);
+  });
+
+  it("returns false for other models", () => {
+    assert.equal(__testing.isMiniMaxTextQuotaModel("tts-1"), false);
+    assert.equal(__testing.isMiniMaxTextQuotaModel("") as boolean, false);
+  });
+});
+
+/* ------------------------------------------------------------------ */
+/*  getMiniMaxAuthErrorMessage                                         */
+/* ------------------------------------------------------------------ */
+describe("getMiniMaxAuthErrorMessage", () => {
+  it("returns token plan message when message includes 'token plan'", () => {
+    const msg = __testing.getMiniMaxAuthErrorMessage("invalid token plan key");
+    assert.ok(msg.includes("Token Plan API key"));
+  });
+
+  it("returns token plan message when message includes 'coding plan'", () => {
+    const msg = __testing.getMiniMaxAuthErrorMessage("coding plan inactive");
+    assert.ok(msg.includes("Token Plan API key"));
+  });
+
+  it("returns token plan message when message includes 'active period'", () => {
+    const msg = __testing.getMiniMaxAuthErrorMessage("active period ended");
+    assert.ok(msg.includes("Token Plan API key"));
+  });
+
+  it("returns generic message for unknown errors", () => {
+    const msg = __testing.getMiniMaxAuthErrorMessage("something else");
+    assert.ok(msg.includes("access denied"));
+  });
+});
+
+/* ------------------------------------------------------------------ */
+/*  getMiniMaxErrorSummary                                             */
+/* ------------------------------------------------------------------ */
+describe("getMiniMaxErrorSummary", () => {
+  it("returns status-only when message is empty", () => {
+    const s = __testing.getMiniMaxErrorSummary(500, "");
+    assert.equal(s, "MiniMax usage endpoint error (500).");
+  });
+
+  it("includes message when under 160 chars", () => {
+    const s = __testing.getMiniMaxErrorSummary(403, "forbidden");
+    assert.equal(s, "MiniMax usage endpoint error (403): forbidden");
+  });
+
+  it("truncates message over 160 chars", () => {
+    const long = "x".repeat(200);
+    const s = __testing.getMiniMaxErrorSummary(429, long);
+    assert.ok(s.length < 200);
+    assert.ok(s.endsWith("..."));
+  });
+});
+
+/* ------------------------------------------------------------------ */
+/*  getClaudePlanLabel                                                 */
+/* ------------------------------------------------------------------ */
+describe("getClaudePlanLabel", () => {
+  it("returns first valid candidate", () => {
+    assert.equal(__testing.getClaudePlanLabel(null, "Pro Plan", "Free"), "Pro Plan");
+  });
+
+  it("skips null/undefined/empty candidates", () => {
+    assert.equal(__testing.getClaudePlanLabel(null, "", "Pro", undefined), "Pro");
+  });
+
+  it("ignores 'claude code' or 'unknown'", () => {
+    assert.equal(__testing.getClaudePlanLabel("Claude Code"), null);
+    assert.equal(__testing.getClaudePlanLabel("Unknown"), null);
+  });
+
+  it("returns null when all candidates are filtered out", () => {
+    assert.equal(__testing.getClaudePlanLabel("claude code", "unknown"), null);
+    assert.equal(__testing.getClaudePlanLabel(), null);
+  });
+});
+
+/* ------------------------------------------------------------------ */
+/*  extractCodeAssist helpers                                          */
+/* ------------------------------------------------------------------ */
+describe("extractCodeAssistOnboardTierId", () => {
+  it("extracts tier id from paidTier", () => {
+    const sub = { paidTier: { id: "pro-tier" } };
+    assert.equal(__testing.extractCodeAssistOnboardTierId(sub), "pro-tier");
+  });
+
+  it("extracts tier id from currentTier when paidTier is absent", () => {
+    const sub = { currentTier: { id: "starter-tier" } };
+    assert.equal(__testing.extractCodeAssistOnboardTierId(sub), "starter-tier");
+  });
+
+  it("returns 'legacy-tier' when no tier data is present", () => {
+    assert.equal(__testing.extractCodeAssistOnboardTierId({}), "legacy-tier");
+  });
+});
+
+describe("extractCodeAssistSubscriptionTier", () => {
+  it("reads tier name from paidTier.name", () => {
+    const info = { paidTier: { name: "ULTRA" } };
+    assert.equal(__testing.extractCodeAssistSubscriptionTier(info), "ULTRA");
+  });
+
+  it("reads tier from currentTier.name", () => {
+    const info = { currentTier: { name: "Pro" } };
+    assert.equal(__testing.extractCodeAssistSubscriptionTier(info), "Pro");
+  });
+
+  it("returns null when nothing matches", () => {
+    assert.equal(__testing.extractCodeAssistSubscriptionTier({}), null);
+  });
+});