diff --git a/docs-site/src/content/docs/guides/web-dashboard.md b/docs-site/src/content/docs/guides/web-dashboard.md
index fa094752c93..a59e92bb180 100644
--- a/docs-site/src/content/docs/guides/web-dashboard.md
+++ b/docs-site/src/content/docs/guides/web-dashboard.md
@@ -203,7 +203,11 @@ The **Usage** summary and Models/Providers tables show end-to-end output through
 
 The **Usage** Models and Providers tables show the estimated priced portion for each row. Requests
 without a matching price or usable usage are counted as excluded beside that amount when the proxy
-reports pricing coverage fields. A row with only excluded requests shows an em dash with that count
+reports pricing coverage fields. Usage that was only partly measured (`unreported` or `unsupported`)
+is not priced, and one excluded part excludes the whole request from that row's priced count. A
+leg that reached no upstream, or that upstream refused with an HTTP error before any output, spent
+nothing and does not; a leg whose response began (or ended without a status) but reported no usage
+may have been billed, so it does. A row with only excluded requests shows an em dash with that count
 instead of a zero-dollar estimate, and a displayed zero-dollar value is a confirmed priced estimate.
 An older proxy that reports no coverage fields keeps a bare em dash with no count, so missing
 coverage stays distinct from an all-excluded row and from a confirmed zero estimate.
diff --git a/src/usage/cost.ts b/src/usage/cost.ts
index d3e7f6a668a..3eb0625e426 100644
--- a/src/usage/cost.ts
+++ b/src/usage/cost.ts
@@ -404,6 +404,15 @@ function vendorPrefixedCost(modelId: string): ReturnType<typeof findVendorCostBy
   return normalize(found.provider) === normalize(claimedVendor) ? found : undefined;
 }
 
+/**
+ * Only measured usage is priced. An `unreported` or `unsupported` row can still carry tokens — a
+ * combo whose first leg failed without usage keeps the second leg's — and pricing them reports an
+ * understated cost as if it were complete.
+ */
+export function isMeasuredStatus(usageStatus: UsageStatus): boolean {
+  return usageStatus === "reported" || usageStatus === "estimated";
+}
+
 function isEstimated(usage: OcxUsage, usageStatus: UsageStatus, priceStatus: ExpectedPriceStatus | "verified"): boolean {
   return usage.estimated === true || usageStatus === "estimated" || priceStatus === "verified-derived";
 }
@@ -592,7 +601,7 @@ export function estimateAttemptCost(
   serviceTier?: ServiceTierInput,
   userOverlays: readonly ExpectedPriceOverlay[] = activeUserCostOverlays(),
 ): AttemptCostEstimate | null {
-  if (!attempt.usage) return null;
+  if (!isMeasuredStatus(attempt.usageStatus) || !attempt.usage) return null;
   const tokens = normalizeCostTokens(attempt.usage);
   if (!tokens) return null;
   const price = resolveMatchedPrice(attempt.provider, attempt.model, overlays, userOverlays, attempt);
@@ -682,7 +691,7 @@ export function estimateRequestCost(
   overlays: readonly ExpectedPriceOverlay[] = EXPECTED_PRICE_OVERLAYS,
   userOverlays: readonly ExpectedPriceOverlay[] = activeUserCostOverlays(),
 ): CostEstimate | null {
-  if (!input.usage) return null;
+  if (!isMeasuredStatus(input.usageStatus) || !input.usage) return null;
   const tokens = normalizeCostTokens(input.usage);
   if (!tokens) return null;
   const price = resolveMatchedPrice(input.provider, input.model, overlays, userOverlays, input);
diff --git a/src/usage/summary.ts b/src/usage/summary.ts
index 6aae84783d1..5cb92a94e16 100644
--- a/src/usage/summary.ts
+++ b/src/usage/summary.ts
@@ -10,7 +10,7 @@ import {
   type PersistedUsageEntry,
   type UsageStatus,
 } from "./log";
-import { type AttemptCostEstimate, type CostEstimate, estimateAttemptCost, estimateRequestCost, serviceTierContext, type ServiceTierContext, tokensPerSecond } from "./cost";
+import { type AttemptCostEstimate, type CostEstimate, estimateAttemptCost, estimateRequestCost, isMeasuredStatus, serviceTierContext, type ServiceTierContext, tokensPerSecond } from "./cost";
 
 /**
  * Canonical range members. The warm-up loop in the management usage route
@@ -303,7 +303,10 @@ export function computeEntryCost(entry: PersistedUsageEntry): EntryCostInfo {
         isPriced = true;
       }
     }
-    return { tier, estimate: null, attemptEstimates, costTotal, isPriced };
+    // A usage-less leg that may have generated billed tokens leaves the total unknown, not short.
+    const unknownCost = entry.attempts.some((attempt, index) =>
+      !attemptEstimates[index] && !attempt.usage && !spentNothing(attempt));
+    return { tier, estimate: null, attemptEstimates, costTotal, isPriced: isPriced && !unknownCost };
   }
   const estimate = estimateRequestCost({
     ...usageModelPriceOptions(entry, entry),
@@ -428,10 +431,6 @@ function blankTotals(): UsageSummaryTotals {
   };
 }
 
-function isMeasuredStatus(status: UsageStatus): boolean {
-  return status === "reported" || status === "estimated";
-}
-
 export interface UsageAttribution {
   requestId: string;
   provider: string;
@@ -814,14 +813,28 @@ function blankRequestCounts(): UsageRequestCounts {
   };
 }
 
+/**
+ * A usage-less attempt that provably cost nothing: it never reached upstream, or upstream refused it
+ * with an HTTP error before any output (providers do not bill a pre-generation 429/401/5xx). One
+ * whose stream began, aborted, or ended without a status may have generated billed tokens, so it
+ * stays an unknown cost. A request made only of such zeros carries neither fact and counts unpriced.
+ */
+function spentNothing(attempt: NonNullable<PersistedUsageEntry["attempts"]>[number] | undefined): boolean {
+  if (!attempt || attempt.usage) return false;
+  if (attempt.sendCount === 0 || attempt.locallyAnswered === true) return true;
+  return attempt.status >= 400 && attempt.streamAborted !== true && attempt.firstOutputMs === undefined;
+}
+
 function bumpRequestCounts(counts: UsageRequestCounts, facts: number, amount = 1): void {
   counts.requests += amount;
   const status = statusFromRequestFacts(facts);
   if (isMeasuredStatus(status)) counts.measuredRequests += amount;
   if (status === "reported") counts.reportedRequests += amount;
   else if (status === "estimated") counts.estimatedRequests += amount;
-  if ((facts & REQUEST_PRICED) !== 0) counts.pricedRequests += amount;
-  if ((facts & REQUEST_UNPRICED) !== 0) counts.unpricedRequests += amount;
+  // Unpriced dominates: one unpriceable part makes the request's cost unknown, and counting it
+  // on both sides overstated price coverage.
+  if ((facts & REQUEST_PRICED) !== 0 && (facts & REQUEST_UNPRICED) === 0) counts.pricedRequests += amount;
+  else counts.unpricedRequests += amount;
 }
 
 function mergeRequestCounts(target: UsageRequestCounts, source: UsageRequestCounts): void {
@@ -1557,7 +1570,7 @@ class StreamingUsageSummaryAccumulator implements UsageSummaryAccumulator {
         : costInfo.estimate;
       const ordinal = this.nextOrdinal++;
       const facts = requestStatusFact(attribution.usageStatus)
-        | (estimate ? REQUEST_PRICED : REQUEST_UNPRICED);
+        | (estimate ? REQUEST_PRICED : spentNothing(entry.attempts?.[index]) ? 0 : REQUEST_UNPRICED);
       const modelKey = this.addModelAttribution(partition, attribution, estimate, ordinal);
       modelFacts.set(modelKey, (modelFacts.get(modelKey) ?? 0) | facts);
       if (this.mode === "row-unique") {
diff --git a/structure/dashboard-and-usage.md b/structure/dashboard-and-usage.md
index 8254b5a1de5..f6181e5176f 100644
--- a/structure/dashboard-and-usage.md
+++ b/structure/dashboard-and-usage.md
@@ -290,7 +290,7 @@ neither the old byte window nor the parsed-entry cap can discard an earlier pref
 surface filtering. `managementUsageMaxReadBytes` remains a recognized compatibility setting for
 bounded legacy readers, but it is not an accuracy limit or tuning knob for `GET /api/usage`.
 A Codex-surface response includes an `accounts` breakdown keyed by stable non-PII `accountLogLabel`; cards join it to the management account DTO for 30-day tokens, API-equivalent cost and coverage. New main-pool rows use `main`; legacy bare `openai` rows remain ambiguous.
-A missing `usage.jsonl` returns a zeroed summary with 200 because a fresh install has no usage. Unmeasured requests remain distinct from measured zero through `measured / reported / unreported / unsupported / estimated` counts and their coverage totals.
+A missing `usage.jsonl` returns a zeroed summary with 200 because a fresh install has no usage. Unmeasured requests remain distinct from measured zero through `measured / reported / unreported / unsupported / estimated` counts and their coverage totals. Cost estimates in `src/usage/cost.ts` price only `reported` or `estimated` usage, so a partly measured row is never given a confident, understated cost; per-row `pricedRequests` / `unpricedRequests` count a request once, unpriced when any attempt is unpriceable, while a usage-less attempt that made no physical send (`sendCount === 0` or `locallyAnswered`) or was refused with an HTTP status >= 400 before any output (no `streamAborted`, no `firstOutputMs`) is a known zero. A usage-less attempt whose response began, aborted, or has no error status may have been billed and stays unpriced.
 Normal dashboard pages use the document as their vertical scroller. In `gui/src/styles.css`, body horizontal overflow is clipped without creating a second scrollport; the mobile open-drawer state also locks document overflow. The shared sidebar stays viewport-height through the end of Codex and Claude account pages. `gui/tests/shared-scroll-browser.ts` checks the built entry and App styles with short/long content, both themes, desktop chrome, collapsed navigation and mobile widths. The Usage tab renders that shape and the main Dashboard shows its 30-day summary. The 200-entry in-memory `requestLog` is not the aggregation source; the JSONL ledger is. Usage table scrollports in `gui/src/styles-usage-workspace.css` contain absolute screen-reader captions so long tables do not extend the outer document beyond the report; `gui/tests/usage-scroll-browser.ts` measures that boundary and last-row reachability at desktop and mobile widths.
 Ledger read failures instead return `500 { error: "read_failed" }`. Shared GUI usage admission reads that body before classifying HTTP failure and also rejects the legacy HTTP-200 envelope, so every shared cache retains its last valid report rather than fabricating zero totals.
 > Decision record: [ADR-0106](decisions/ADR-0106-usage-read-failure-contract.md)
diff --git a/tests/usage/usage-cost.test.ts b/tests/usage/usage-cost.test.ts
index 2ce91c458b0..2ada075897e 100644
--- a/tests/usage/usage-cost.test.ts
+++ b/tests/usage/usage-cost.test.ts
@@ -25,6 +25,8 @@ import {
   refreshUserCostOverlays,
   userCostOverlayVersion,
 } from "../../src/usage/user-cost-overlays";
+import { summarizeUsage } from "../../src/usage/summary";
+import type { PersistedUsageAttempt } from "../../src/usage/log";
 import type { OcxConfig } from "../../src/types";
 
 const RATE = { input: 3, output: 15, cacheRead: 0.3, cacheWrite: 3.75 };
@@ -763,6 +765,74 @@ describe("estimateRequestCost", () => {
     expect(est?.estimated).toBe(true);
     expect(estimateRequestCost({ provider: "p", model: "m", usageStatus: "unreported" }, overlays)).toBeNull();
   });
+
+  test("usage that was only partly measured gets no confident price", () => {
+    const overlays: ExpectedPriceOverlay[] = [
+      { provider: "p", modelId: "m", cost4: { input: 1, output: 1, cacheRead: 0, cacheWrite: 0 }, source: "s", verifiedAt: "2026-07-20", status: "verified" },
+    ];
+    // A combo row whose first leg failed without usage is `unreported` while still carrying the
+    // second leg's tokens; pricing those tokens reports an understated cost as if complete.
+    const usage = { inputTokens: 10, outputTokens: 5 };
+    for (const usageStatus of ["unreported", "unsupported"] as const) {
+      expect(estimateRequestCost({ provider: "p", model: "m", usageStatus, usage }, overlays)).toBeNull();
+      expect(estimateAttemptCost({ ordinal: 1, provider: "p", model: "m", usageStatus, usage }, overlays)).toBeNull();
+    }
+  });
+});
+
+describe("summary price coverage on partly measured requests", () => {
+  const attempt = (ordinal: number, usage?: { inputTokens: number; outputTokens: number }, sendCount = 1) => ({
+    ordinal, provider: "openai", model: "gpt-5.5", adapter: "openai-responses",
+    status: usage ? 200 : 429, durationMs: 10, sendCount, recoveryKinds: [],
+    usageStatus: usage ? "reported" as const : "unreported" as const,
+    ...(usage ? { usage } : {}),
+  });
+  const row = (requestId: string, attempts: PersistedUsageAttempt[]) => ({
+    requestId, timestamp: Date.UTC(2026, 5, 28), provider: "openai", model: "gpt-5.5",
+    status: 200, durationMs: 20, usageStatus: "unreported" as const, attempts,
+  });
+  const gpt = (entries: ReturnType<typeof row>[]) =>
+    summarizeUsage(entries, "30d", Date.UTC(2026, 5, 28, 12)).models.find(model => model.model === "gpt-5.5")!;
+
+  test("a request with an unpriceable part counts unpriced, never both", () => {
+    const partial = { ...attempt(2, { inputTokens: 100, outputTokens: 10 }), usageStatus: "unreported" as const };
+    expect(gpt([row("mixed", [attempt(1, { inputTokens: 100, outputTokens: 10 }), partial])]))
+      .toMatchObject({ requests: 1, pricedRequests: 0, unpricedRequests: 1 });
+  });
+
+  test("a leg that cost nothing is a known zero and does not unprice the request", () => {
+    const served = attempt(2, { inputTokens: 100, outputTokens: 10 });
+    const priced = { requests: 1, pricedRequests: 1, unpricedRequests: 0 };
+    expect(gpt([row("no-send", [{ ...attempt(1, undefined, 0), status: 0 }, served])])).toMatchObject(priced);
+    expect(gpt([row("local", [{ ...attempt(1), status: 200, locallyAnswered: true }, served])])).toMatchObject(priced);
+    // Sent, refused with an HTTP error before any output: providers do not bill it.
+    expect(gpt([row("refused", [attempt(1), served])])).toMatchObject(priced);
+  });
+
+  test("a leg that may have generated tokens without reporting usage unprices the request", () => {
+    const served = attempt(2, { inputTokens: 100, outputTokens: 10 });
+    const unpriced = { requests: 1, pricedRequests: 0, unpricedRequests: 1 };
+    // Mid-stream failure after the 200 head, a stream that began before its error, and a 200 that
+    // simply never carried a usage frame.
+    expect(gpt([row("aborted", [{ ...attempt(1), status: 502, streamAborted: true }, served])])).toMatchObject(unpriced);
+    expect(gpt([row("began", [{ ...attempt(1), status: 503, firstOutputMs: 40 }, served])])).toMatchObject(unpriced);
+    expect(gpt([row("silent", [{ ...attempt(1), status: 200 }, served])])).toMatchObject(unpriced);
+  });
+
+  test("a retry row reported from its last leg does not total a cost an earlier leg may have added", () => {
+    // Non-combo retry: the row's status and usage come from the served leg alone, so the row reads
+    // `reported` while an earlier leg died mid-stream without usage.
+    const usage = { inputTokens: 100, outputTokens: 10 };
+    const entry = {
+      ...row("retry", [{ ...attempt(1), status: 502, streamAborted: true }, attempt(2, usage)]),
+      usageStatus: "reported" as const, usage,
+    };
+    expect(summarizeUsage([entry], "30d", Date.UTC(2026, 5, 28, 12)).summary)
+      .toMatchObject({ requests: 1, pricedRequests: 0, unpricedRequests: 1, estimatedCostUsd: 0 });
+    const refused = { ...entry, attempts: [attempt(1), attempt(2, usage)] };
+    expect(summarizeUsage([refused], "30d", Date.UTC(2026, 5, 28, 12)).summary)
+      .toMatchObject({ requests: 1, pricedRequests: 1, unpricedRequests: 0 });
+  });
 });
 
 describe("OpenAI API-reference pricing", () => {
diff --git a/tests/usage/usage-summary.test.ts b/tests/usage/usage-summary.test.ts
index c109d861f4d..50242799917 100644
--- a/tests/usage/usage-summary.test.ts
+++ b/tests/usage/usage-summary.test.ts
@@ -1958,7 +1958,7 @@ describe("UsageSummaryAccumulator modes", () => {
       attemptCount: 2,
       measuredRequests: 0,
       reportedRequests: 0,
-      pricedRequests: 1,
+      pricedRequests: 0,
       unpricedRequests: 1,
     });
     const dayOther = compactSummary.days.find(day => day.requests > 0)?.models