fix(FN-1014): add fallback reset time for Claude session window when API omits resets_at

- When the Claude usage API omits resets_at for the 5-hour session window, fall back to using the full window duration as resetMs
- This enables pace calculation and reset text display even without an explicit reset timestamp
- Update existing test to verify fallback behavior (resetMs = 5h, resetText = 'resets in 5h')
- Add new test for pace calculation with fallback reset time

packages/dashboard/src/usage.test.ts

@@ -769,7 +769,7 @@ describe("usage", () => {
       expect(weeklyWindow.resetAt).toBeDefined();
     });
 
-    it("omits resetAt when API response has no resets_at field", async () => {
+    it("uses fallback reset time for session window when API omits resets_at", async () => {
       setupClaudeMocks({
         credFileContent: {
           accessToken: "test-token",
@@ -781,7 +781,7 @@ describe("usage", () => {
       setupClaudeApiResponse({
         five_hour: {
           utilization: 30.0,
-          // no resets_at field
+          // no resets_at field — triggers fallback
         },
       });
 
@@ -791,7 +791,40 @@ describe("usage", () => {
       expect(claude.status).toBe("ok");
       const sessionWindow = claude.windows.find((w) => w.label.includes("Session"))!;
       expect(sessionWindow.resetAt).toBeUndefined();
-      expect(sessionWindow.resetText).toBeNull();
+      // Fallback: when resets_at is missing, session window gets resetMs = 5h
+      expect(sessionWindow.resetMs).toBe(5 * 60 * 60 * 1000);
+      expect(sessionWindow.resetText).toBe("resets in 5h");
+    });
+
+    it("calculates pace for session window with fallback reset time", async () => {
+      setupClaudeMocks({
+        credFileContent: {
+          accessToken: "test-token",
+          scopes: ["user:profile"],
+          subscriptionType: "pro",
+        },
+      });
+
+      setupClaudeApiResponse({
+        five_hour: {
+          utilization: 50.0,
+          // no resets_at — fallback uses full 5h duration
+        },
+      });
+
+      const providers = await fetchAllProviderUsage();
+      const claude = providers.find((p) => p.name === "Claude")!;
+
+      expect(claude.status).toBe("ok");
+      const sessionWindow = claude.windows.find((w) => w.label.includes("Session"))!;
+      expect(sessionWindow.percentUsed).toBe(50);
+      // With fallback resetMs = 5h and percentUsed = 50%, the window duration
+      // and reset time are both set, enabling pace indicator on the frontend.
+      expect(sessionWindow.windowDurationMs).toBe(5 * 60 * 60 * 1000);
+      expect(sessionWindow.resetMs).toBe(5 * 60 * 60 * 1000);
+      expect(sessionWindow.resetText).toBe("resets in 5h");
+      // resetAt stays undefined because the API didn't provide it
+      expect(sessionWindow.resetAt).toBeUndefined();
     });
 
     it("handles empty JSON object from API gracefully", async () => {

packages/dashboard/src/usage.ts

@@ -842,6 +842,13 @@ async function fetchClaudeUsage(): Promise<ProviderUsage> {
         const msLeft = new Date(resetAtValue).getTime() - Date.now();
         resetMs = msLeft > 0 ? msLeft : 0;
         resetText = msLeft > 0 ? `resets in ${formatDuration(msLeft)}` : "resetting now";
+      } else if (windowDurationMs === FIVE_HOURS_MS) {
+        // Fallback for session window: when the API doesn't provide reset time,
+        // use the full window duration as a best-effort estimate. This enables
+        // pace calculation and reset text for the session (5h) window even when
+        // the API omits resets_at / reset_at / resetAt fields.
+        resetMs = windowDurationMs;
+        resetText = "resets in 5h";
       }
 
       return {