fix(review): address CodeRabbit and Gemini review comments

- Design doc: update "No UI changes" to reflect cost disclaimer
- Plan doc: fix MD001 heading level jump (### after #)
- pricing.ts: rename to PRICING_MAP, add isLiteLLMPricing type guard,
  pre-compute LOWERCASE_KEY_MAP for O(1) case-insensitive lookups
- SessionContextHeader: simplify cost disclaimer JSX into single span
- Tests: fix no-empty-function lint (() => {} → () => undefined)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/plans/2026-02-23-unify-cost-calculation-design.md

@@ -62,7 +62,7 @@ Create a single shared pricing module that both processes import.
 
 - Report costs become more accurate (tiered pricing, 206 models instead of 6)
 - Cost numbers between chat view and Session Report now agree exactly
-- No UI changes — same components, same layout
+- Small UI change: Visible Context header adds a "parent only · view full cost" action when available
 
 ## Out of Scope
 

docs/plans/2026-02-23-unify-cost-calculation.md

@@ -10,6 +10,8 @@
 
 ---
 
+## Tasks
+
 ### Task 1: Create the shared pricing module with tests
 
 **Files:**

src/renderer/components/chat/SessionContextPanel/components/SessionContextHeader.tsx

@@ -134,22 +134,22 @@ export const SessionContextHeader = ({
               <span className="font-medium tabular-nums" style={{ color: COLOR_TEXT_SECONDARY }}>
                 {formatCostUsd(sessionMetrics.costUsd)}
               </span>
-              <span style={{ color: COLOR_TEXT_MUTED }}> (parent only</span>
-              {onViewReport ? (
-                <span>
-                  <span style={{ color: COLOR_TEXT_MUTED }}> · </span>
-                  <button
-                    onClick={onViewReport}
-                    className="underline"
-                    style={{ color: COLOR_TEXT_SECONDARY }}
-                  >
-                    view full cost
-                  </button>
-                  <span style={{ color: COLOR_TEXT_MUTED }}>)</span>
-                </span>
-              ) : (
-                <span style={{ color: COLOR_TEXT_MUTED }}>)</span>
-              )}
+              <span style={{ color: COLOR_TEXT_MUTED }}>
+                {' (parent only'}
+                {onViewReport && (
+                  <>
+                    {' · '}
+                    <button
+                      onClick={onViewReport}
+                      className="underline"
+                      style={{ color: COLOR_TEXT_SECONDARY }}
+                    >
+                      view full cost
+                    </button>
+                  </>
+                )}
+                {')'}
+              </span>
             </div>
           )}
         </div>

src/shared/utils/pricing.ts

@@ -22,19 +22,28 @@ export interface DisplayPricing {
 
 const TIER_THRESHOLD = 200_000;
 
-const pricingMap = pricingData as Record<string, unknown>;
+const PRICING_MAP = pricingData as Record<string, unknown>;
 
-function tryGetPricing(key: string): LiteLLMPricing | null {
-  const entry = pricingMap[key];
-  if (
-    entry &&
+// Pre-compute lowercase key map for O(1) case-insensitive lookups
+const LOWERCASE_KEY_MAP = new Map<string, string>();
+for (const key of Object.keys(PRICING_MAP)) {
+  if (!LOWERCASE_KEY_MAP.has(key.toLowerCase())) {
+    LOWERCASE_KEY_MAP.set(key.toLowerCase(), key);
+  }
+}
+
+function isLiteLLMPricing(entry: unknown): entry is LiteLLMPricing {
+  return (
+    !!entry &&
     typeof entry === 'object' &&
     'input_cost_per_token' in entry &&
     'output_cost_per_token' in entry
-  ) {
-    return entry as LiteLLMPricing;
-  }
-  return null;
+  );
+}
+
+function tryGetPricing(key: string): LiteLLMPricing | null {
+  const entry = PRICING_MAP[key];
+  return isLiteLLMPricing(entry) ? entry : null;
 }
 
 export function getPricing(modelName: string): LiteLLMPricing | null {
@@ -42,14 +51,9 @@ export function getPricing(modelName: string): LiteLLMPricing | null {
   if (exact) return exact;
 
   const lowerName = modelName.toLowerCase();
-  const lower = tryGetPricing(lowerName);
-  if (lower) return lower;
-
-  for (const key of Object.keys(pricingMap)) {
-    if (key.toLowerCase() === lowerName) {
-      const match = tryGetPricing(key);
-      if (match) return match;
-    }
+  const originalKey = LOWERCASE_KEY_MAP.get(lowerName);
+  if (originalKey) {
+    return tryGetPricing(originalKey);
   }
 
   return null;

test/main/utils/costCalculation.test.ts

@@ -84,7 +84,7 @@ describe('Cost Calculation', () => {
     });
 
     it('should return 0 cost when model pricing not found', () => {
-      const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
+      const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => undefined);
       const messages: ParsedMessage[] = [
         {
           type: 'assistant',

test/shared/utils/pricing.test.ts

@@ -55,7 +55,7 @@ describe('Shared Pricing Module', () => {
     });
 
     it('should return 0 for unknown models', () => {
-      const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
+      const warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => undefined);
       const cost = calculateMessageCost('unknown-model', 1000, 500, 0, 0);
       expect(cost).toBe(0);
       expect(warnSpy).toHaveBeenCalledWith(