diff --git a/components/graph-view.tsx b/components/graph-view.tsx
index 25acc8c..293bf44 100644
--- a/components/graph-view.tsx
+++ b/components/graph-view.tsx
@@ -303,7 +303,7 @@ function graphUsageLabel(costs: Pick<GraphCostSummary, "stages">): string {
 	const plan = stages.some((stage) => (stage.subscriptionRuns ?? 0) > 0);
 	const priced = stages.some((stage) => stage.runs - stage.unpricedRuns - (stage.subscriptionRuns ?? 0) > 0);
 	const dollars = displayCostTotals(costs).totalDollars;
-	return plan ? (priced ? `$${dollars.toFixed(2)} API + ChatGPT plan` : "ChatGPT plan") : `$${dollars.toFixed(2)}`;
+	return plan ? (priced ? `$${dollars.toFixed(2)} API + ChatGPT plan` : "ChatGPT plan") : priced ? `$${dollars.toFixed(2)}` : "—";
 }
 
 /**
diff --git a/src/core/cost-summary.ts b/src/core/cost-summary.ts
index f6c9ff0..27045b1 100644
--- a/src/core/cost-summary.ts
+++ b/src/core/cost-summary.ts
@@ -106,6 +106,9 @@ function stageDollars(model: string, steps: readonly CallUsage[], price: CallPri
 /** Merge one step-set's tokens into an accumulating CallUsage. */
 function mergeTokens(into: CallUsage, steps: readonly CallUsage[]): void {
 	const summed = sumSteps(steps);
+	// Fold this before updating total writes, so an older write-bearing
+	// aggregate with a missing split remains unknown even after fresh data.
+	into.cacheWrite1hTokens = sumSteps([into, summed]).cacheWrite1hTokens;
 	into.inputTokens = (into.inputTokens ?? 0) + (summed.inputTokens ?? 0);
 	into.outputTokens = (into.outputTokens ?? 0) + (summed.outputTokens ?? 0);
 	into.cacheReadTokens = (into.cacheReadTokens ?? 0) + (summed.cacheReadTokens ?? 0);
diff --git a/tests/graph-pricing.test.tsx b/tests/graph-pricing.test.tsx
new file mode 100644
index 0000000..ee1aa05
--- /dev/null
+++ b/tests/graph-pricing.test.tsx
@@ -0,0 +1,60 @@
+import React from "react";
+(globalThis as Record<string, unknown>).React = React;
+import assert from "node:assert/strict";
+import test from "node:test";
+import { renderToStaticMarkup } from "react-dom/server";
+import { GraphCostControl } from "../components/graph-view.tsx";
+import { graphCostSummary } from "../src/core/cost-summary.ts";
+import { callCost } from "../src/server/pricing.ts";
+import type { CallUsage, ExtractionRunUsage } from "../src/core/contracts.ts";
+
+const usage = (over: Partial<CallUsage> = {}): CallUsage => ({ inputTokens: 1000, outputTokens: 100, cacheReadTokens: 0, cacheWriteTokens: 20_000, reasoningTokens: 0, ...over });
+const run = (steps: CallUsage[], model = "anthropic:claude-haiku-4-5", at = 1): ExtractionRunUsage => ({ startedAt: at, at: "fixture", durationMs: 1, stages: { extractor: { model, steps }, auditor: { model, steps } } });
+const summary = (runs: ExtractionRunUsage[]) => graphCostSummary({ chats: [{ title: "fixture", extractions: runs }], sources: [] }, callCost);
+const headline = (runs: ExtractionRunUsage[]) => renderToStaticMarkup(<GraphCostControl costs={summary(runs)} />);
+
+test("wholly unpriced historical graph costs render unknown, not known-zero dollars", () => {
+	const historical = run([usage()]); // missing long-cache split
+	const costs = summary([historical]);
+	assert.equal(costs.totalDollars, 0);
+	assert.equal(costs.unpricedRuns, 1);
+	assert.equal(costs.stages.extraction.unpricedRuns, 1);
+	const html = headline([historical]);
+	assert.match(html, />—<\/button>/);
+	assert.doesNotMatch(html, /\$0\.00/);
+});
+
+test("known zero, mixed priced/unknown, and subscription headline semantics stay distinct", () => {
+	const zero = run([usage({ inputTokens: 0, outputTokens: 0, cacheWriteTokens: 0 })]);
+	assert.match(headline([zero]), />\$0\.00<\/button>/, "known zero is not unknown");
+	const priced = run([usage({ cacheWrite1hTokens: 0 })]);
+	const historical = run([usage()], undefined, 2);
+	const mixed = summary([priced, historical]);
+	assert.equal(mixed.unpricedRuns, 1);
+	assert.ok(mixed.totalDollars > 0);
+	assert.match(headline([priced, historical]), new RegExp(`>\\$${mixed.totalDollars.toFixed(2).replace(".", "\\.")}<\\/button>`));
+	const plan = run([usage()], "chatgpt:fixture");
+	assert.match(headline([plan]), />ChatGPT plan<\/button>/);
+	assert.match(headline([plan, zero]), />\$0\.00 API \+ ChatGPT plan<\/button>/);
+});
+
+test("graph stage and recent-run aggregates preserve known one-hour cache writes", () => {
+	const costs = summary([run([usage({ cacheWrite1hTokens: 20_000 })]), run([usage({ cacheWrite1hTokens: 5000 })], undefined, 2)]);
+	assert.equal(costs.stages.extraction.tokens.cacheWrite1hTokens, 25_000);
+	assert.equal(costs.stages.audit.tokens.cacheWrite1hTokens, 25_000);
+	assert.deepEqual(costs.runs.map((r) => r.tokens.cacheWrite1hTokens), [10_000, 40_000]);
+});
+
+test("unknown historical long-cache splits stay unknown regardless of merge order", () => {
+	const known = run([usage({ cacheWrite1hTokens: 20_000 })]);
+	const historical = run([usage()], undefined, 2);
+	for (const runs of [[known, historical], [historical, known]]) {
+		const costs = summary(runs);
+		assert.equal(costs.stages.extraction.tokens.cacheWrite1hTokens, undefined);
+		assert.equal(costs.stages.audit.tokens.cacheWrite1hTokens, undefined);
+	}
+	const mixedWithinRun = summary([run([usage({ cacheWrite1hTokens: 20_000 }), usage()])]);
+	assert.equal(mixedWithinRun.stages.extraction.tokens.cacheWrite1hTokens, undefined);
+	const absentNoWrites = run([usage({ cacheWriteTokens: 0 })], undefined, 2);
+	assert.equal(summary([absentNoWrites, known]).stages.extraction.tokens.cacheWrite1hTokens, 20_000, "absence without writes must not poison known write detail");
+});