fix(status): account cached prompt tokens

src/agents/agents.test.ts

@@ -36,12 +36,17 @@ describe("pi agent helpers", () => {
   it("parses final assistant message and preserves usage meta", () => {
     const stdout = [
       '{"type":"message_start","message":{"role":"assistant"}}',
-      '{"type":"message_end","message":{"role":"assistant","content":[{"type":"text","text":"hello world"}],"usage":{"input":10,"output":5},"model":"pi-1","provider":"inflection","stopReason":"end"}}',
+      '{"type":"message_end","message":{"role":"assistant","content":[{"type":"text","text":"hello world"}],"usage":{"input":10,"output":5,"cacheRead":100,"cacheWrite":20,"totalTokens":135},"model":"pi-1","provider":"inflection","stopReason":"end"}}',
     ].join("\n");
     const parsed = piSpec.parseOutput(stdout);
     expect(parsed.texts?.[0]).toBe("hello world");
     expect(parsed.meta?.provider).toBe("inflection");
     expect((parsed.meta?.usage as { output?: number })?.output).toBe(5);
+    expect((parsed.meta?.usage as { cacheRead?: number })?.cacheRead).toBe(100);
+    expect((parsed.meta?.usage as { cacheWrite?: number })?.cacheWrite).toBe(
+      20,
+    );
+    expect((parsed.meta?.usage as { total?: number })?.total).toBe(135);
   });
 
   it("piSpec carries tool names when present", () => {

src/agents/pi.ts

@@ -6,11 +6,12 @@ import type {
   AgentSpec,
   AgentToolResult,
 } from "./types.js";
+import { normalizeUsage, type UsageLike } from "./usage.js";
 
 type PiAssistantMessage = {
   role?: string;
   content?: Array<{ type?: string; text?: string }>;
-  usage?: { input?: number; output?: number };
+  usage?: UsageLike;
   model?: string;
   provider?: string;
   stopReason?: string;
@@ -153,7 +154,7 @@ function parsePiJson(raw: string): AgentParseResult {
         model: lastAssistant.model,
         provider: lastAssistant.provider,
         stopReason: lastAssistant.stopReason,
-        usage: lastAssistant.usage,
+        usage: normalizeUsage(lastAssistant.usage),
       }
     : undefined;
 

src/agents/usage.ts

@@ -0,0 +1,69 @@
+export type UsageLike = {
+  input?: number;
+  output?: number;
+  cacheRead?: number;
+  cacheWrite?: number;
+  total?: number;
+  // Some agents/logs emit alternate naming.
+  totalTokens?: number;
+  total_tokens?: number;
+  cache_read?: number;
+  cache_write?: number;
+};
+
+const asFiniteNumber = (value: unknown): number | undefined => {
+  if (typeof value !== "number") return undefined;
+  if (!Number.isFinite(value)) return undefined;
+  return value;
+};
+
+export function normalizeUsage(raw?: UsageLike | null):
+  | {
+      input?: number;
+      output?: number;
+      cacheRead?: number;
+      cacheWrite?: number;
+      total?: number;
+    }
+  | undefined {
+  if (!raw) return undefined;
+
+  const input = asFiniteNumber(raw.input);
+  const output = asFiniteNumber(raw.output);
+  const cacheRead = asFiniteNumber(raw.cacheRead ?? raw.cache_read);
+  const cacheWrite = asFiniteNumber(raw.cacheWrite ?? raw.cache_write);
+  const total = asFiniteNumber(
+    raw.total ?? raw.totalTokens ?? raw.total_tokens,
+  );
+
+  if (
+    input === undefined &&
+    output === undefined &&
+    cacheRead === undefined &&
+    cacheWrite === undefined &&
+    total === undefined
+  ) {
+    return undefined;
+  }
+
+  return {
+    input,
+    output,
+    cacheRead,
+    cacheWrite,
+    total,
+  };
+}
+
+export function derivePromptTokens(usage?: {
+  input?: number;
+  cacheRead?: number;
+  cacheWrite?: number;
+}): number | undefined {
+  if (!usage) return undefined;
+  const input = usage.input ?? 0;
+  const cacheRead = usage.cacheRead ?? 0;
+  const cacheWrite = usage.cacheWrite ?? 0;
+  const sum = input + cacheRead + cacheWrite;
+  return sum > 0 ? sum : undefined;
+}