diff --git a/README.md b/README.md
index f9258cf..cb161f6 100644
--- a/README.md
+++ b/README.md
@@ -390,7 +390,8 @@ SIPp adds load in steps, such as 50 more calls/s every minute. For each step:
 - Its latency counts the calls whose request was **sent** in the step, even when the answer came
   in the next one.
 - Its attempted, failed and retransmitted calls are SIPp's 10-second counters (`-trace_stat`)
-  that fall in the step. Failed % is failed / attempted.
+  that fall in the step. Failed % is failed / attempted. So `every` must be a multiple of 10 s:
+  `perfkit validate` rejects a `15s` step, whose counters would mix two steps.
 - **Warm-up.** With `warmup` set, the first step still runs its full `every`, but it is measured
   only from `warmup` after it starts: calls sent, and 10-second counters whose period mid-point
   falls, before that don't count. A cold JIT (EdgePort's JVM and GraalJS) makes the first seconds
diff --git a/docs/perfkit-yaml.md b/docs/perfkit-yaml.md
index f3b19b3..40ec244 100644
--- a/docs/perfkit-yaml.md
+++ b/docs/perfkit-yaml.md
@@ -32,6 +32,7 @@ Rules for the whole file:
 | `project.siteUrl` | URL | yes | | Where the report pages are published, like `https://routr.io/benchmarks`. |
 | `project.accent` | string | yes | | 6-digit hex color, like `#5FCFCE`: the page's accent color. |
 | `project.logo` | path | no | none | An `.svg` file. Without it, the nav shows `project.name`. |
+| `project.favicon` | path | no | none | An `.svg` file: the browser tab's icon on every page. Read when the run starts and inlined into report.json and live.json. Without it, the pages have no icon. |
 | `project.title` | string | yes | | The page's headline. |
 | `project.lead` | string | yes | | The paragraph under the headline. |
 | `project.live.url` | URL | no | `live.url`, else `https://<live.domain>/live.json` | Where the benchmarks page polls a run in progress. Goes into report.json, so the published page knows it. |
@@ -124,7 +125,7 @@ the other kind rejects them.
 | `load.unit` | string | no | `calls` | What one SIPp call is, as a lowercase plural noun shown on the page (`calls`, `messages`). Copied into each report.json benchmark as `unit`. |
 | `load.rate.start` | number (calls/s) | *capacity*: yes | | The first step's rate. |
 | `load.rate.step` | number (calls/s) | *capacity*: yes | | Added at each step. |
-| `load.rate.every` | duration | *capacity*: yes | | How long each step lasts. |
+| `load.rate.every` | duration | *capacity*: yes | | How long each step lasts. A multiple of 10 s, because SIPp reports its counters every 10 s; `15s` is rejected (`expected a multiple of 10 s (SIPp reports every 10 s); got 15s`). |
 | `load.rate.max` | number (calls/s) | *capacity*: yes | | The ramp stops here. Reaching it without breaking a rule makes the limit a lower bound. |
 | `load.rate.cps` | number (calls/s) | *soak*: yes | | The fixed rate. Keep it well below saturation: a soak looks for leaks, not limits. |
 | `telemetry` | object | no | `{ otlp: false }` | |
@@ -156,6 +157,7 @@ project:
   siteUrl: https://routr.io/benchmarks
   accent: "#5FCFCE"               # 6-digit hex; the page's accent color
   logo: logo.svg                  # optional SVG; without it the nav shows project.name
+  favicon: favicon.svg            # optional SVG; the browser tab's icon
   title: How much SIP traffic Routr handles.
   lead: We run these tests after significant changes to the code, on dedicated DigitalOcean servers, one for Routr and one for the load generator. The EdgePort runs alone to find its limit; the whole stack runs for hours to catch leaks.
 infra:
diff --git a/docs/report-page.md b/docs/report-page.md
index 1e4d701..f7507fd 100644
--- a/docs/report-page.md
+++ b/docs/report-page.md
@@ -20,7 +20,8 @@ history and picker list every run published since, and a newer perfkit redraws i
 
 ## Nav and header
 
-The nav has the project's logo, the run picker and a link to the run's `report.json`. The picker
+With `project.faviconSvg` in report.json, every page and shell links it as the tab's icon. The
+nav has the project's logo, the run picker and a link to the run's `report.json`. The picker
 lists up to 8 runs, newest first, each a link to its page; "See all" jumps to Previous runs.
 
 The header has the verdict pill, `N of M benchmarks passed`, followed by how many were not run,
diff --git a/docs/report-v1.md b/docs/report-v1.md
index 81d4fcd..924720b 100644
--- a/docs/report-v1.md
+++ b/docs/report-v1.md
@@ -41,6 +41,7 @@ Rules for both files:
 | :--- | :--- | :--- |
 | `project.name`, `repo`, `siteUrl`, `accent`, `title`, `lead` | string | Copied from perfkit.yaml. |
 | `project.logoSvg` | string | The SVG markup of `project.logo`, inlined. Present only when perfkit.yaml has `logo`. |
+| `project.faviconSvg` | string | The SVG markup of `project.favicon`, inlined. Every page links it as its icon (a URL-encoded `data:image/svg+xml` URI). Present only when perfkit.yaml has `favicon`. |
 | `project.live.url` | URL | Where the latest page polls live.json: `project.live.url`, else `live.url`, else `https://<live.domain>/live.json` of perfkit.yaml. Absent without them. |
 
 ### run
diff --git a/schemas/live-v1.schema.json b/schemas/live-v1.schema.json
index 75622b7..1beb518 100644
--- a/schemas/live-v1.schema.json
+++ b/schemas/live-v1.schema.json
@@ -84,6 +84,10 @@
           "type": "string",
           "pattern": "<svg[\\s>]"
         },
+        "faviconSvg": {
+          "type": "string",
+          "pattern": "<svg[\\s>]"
+        },
         "title": {
           "type": "string",
           "minLength": 1
diff --git a/schemas/perfkit-v1.schema.json b/schemas/perfkit-v1.schema.json
index 9fbbba5..a84a7dd 100644
--- a/schemas/perfkit-v1.schema.json
+++ b/schemas/perfkit-v1.schema.json
@@ -29,6 +29,10 @@
           "type": "string",
           "minLength": 1
         },
+        "favicon": {
+          "type": "string",
+          "minLength": 1
+        },
         "title": {
           "type": "string",
           "minLength": 1
diff --git a/schemas/report-v1.schema.json b/schemas/report-v1.schema.json
index bdbf2e3..52b89f9 100644
--- a/schemas/report-v1.schema.json
+++ b/schemas/report-v1.schema.json
@@ -29,6 +29,10 @@
           "type": "string",
           "pattern": "<svg[\\s>]"
         },
+        "faviconSvg": {
+          "type": "string",
+          "pattern": "<svg[\\s>]"
+        },
         "title": {
           "type": "string",
           "minLength": 1
diff --git a/src/cli/createStartExecutor.ts b/src/cli/createStartExecutor.ts
index 4bd37ce..f05ac75 100644
--- a/src/cli/createStartExecutor.ts
+++ b/src/cli/createStartExecutor.ts
@@ -30,6 +30,12 @@ export function createStartExecutor(deps: CliDeps): BenchmarkExecutor {
           "utf8"
         )
       : undefined;
+    const faviconSvg = config.project.favicon
+      ? await readFile(
+          join(dirname(options.configPath), config.project.favicon),
+          "utf8"
+        )
+      : undefined;
     await createStartRun({
       remote: createSshRemote({
         ssh: infra.ssh,
@@ -47,6 +53,7 @@ export function createStartExecutor(deps: CliDeps): BenchmarkExecutor {
       plan,
       config,
       ...(logoSvg ? { logoSvg: logoSvg.trim() } : {}),
+      ...(faviconSvg ? { faviconSvg: faviconSvg.trim() } : {}),
       hosts: {
         uutIp: run.uut.privateIp,
         loadgenIp: run.loadgen.privateIp,
diff --git a/src/cli/runRunCommand.ts b/src/cli/runRunCommand.ts
index da76d5b..38aab14 100644
--- a/src/cli/runRunCommand.ts
+++ b/src/cli/runRunCommand.ts
@@ -270,6 +270,13 @@ async function runLocal(
         await deps.readFile(join(dirname(options.config), config.project.logo))
       ).trim()
     : undefined;
+  const favicon = config.project.favicon
+    ? (
+        await deps.readFile(
+          join(dirname(options.config), config.project.favicon)
+        )
+      ).trim()
+    : undefined;
   try {
     await createStartRun({
       remote: createLocalRemote({ run: infra.runProgram }),
@@ -284,6 +291,7 @@ async function runLocal(
       plan,
       config,
       ...(logo ? { logoSvg: logo } : {}),
+      ...(favicon ? { faviconSvg: favicon } : {}),
       hosts: {
         uutIp: "127.0.0.1",
         loadgenIp: "127.0.0.1",
diff --git a/src/orchestrate/createStartRun.ts b/src/orchestrate/createStartRun.ts
index facd991..13ebc9e 100644
--- a/src/orchestrate/createStartRun.ts
+++ b/src/orchestrate/createStartRun.ts
@@ -146,6 +146,7 @@ export function createStartRun(deps: StartRunDeps) {
         plan: input.plan,
         config: input.config,
         ...(input.logoSvg ? { logoSvg: input.logoSvg } : {}),
+        ...(input.faviconSvg ? { faviconSvg: input.faviconSvg } : {}),
         hosts: input.hosts,
         ...(input.live ? { live: input.live } : {}),
         machines: { uut, loadgen },
diff --git a/src/orchestrate/runState.schema.ts b/src/orchestrate/runState.schema.ts
index 02e413b..54c1889 100644
--- a/src/orchestrate/runState.schema.ts
+++ b/src/orchestrate/runState.schema.ts
@@ -50,6 +50,7 @@ export const runStateSchema = z.strictObject({
   plan: planSchema,
   config: perfkitConfigSchema,
   logoSvg: z.string().optional(),
+  faviconSvg: z.string().optional(),
   hosts: z.strictObject({
     uutIp: z.ipv4(),
     loadgenIp: z.ipv4(),
diff --git a/src/orchestrate/startRun.schema.ts b/src/orchestrate/startRun.schema.ts
index 1889eda..885553f 100644
--- a/src/orchestrate/startRun.schema.ts
+++ b/src/orchestrate/startRun.schema.ts
@@ -15,6 +15,7 @@ export const startRunInputSchema = z.strictObject({
     plan: true,
     config: true,
     logoSvg: true,
+    faviconSvg: true,
     hosts: true,
     live: true
   }).shape,
diff --git a/src/orchestrate/toReportProject.ts b/src/orchestrate/toReportProject.ts
index f025ca0..a2f95a1 100644
--- a/src/orchestrate/toReportProject.ts
+++ b/src/orchestrate/toReportProject.ts
@@ -21,6 +21,7 @@ export function toReportProject(state: RunState): Report["project"] {
     siteUrl: project.siteUrl,
     accent: project.accent,
     ...(state.logoSvg ? { logoSvg: state.logoSvg } : {}),
+    ...(state.faviconSvg ? { faviconSvg: state.faviconSvg } : {}),
     title: project.title,
     lead: project.lead,
     ...(liveUrl ? { live: { url: liveUrl } } : {})
diff --git a/src/render/createRenderSite.ts b/src/render/createRenderSite.ts
index ded1562..ad8598c 100644
--- a/src/render/createRenderSite.ts
+++ b/src/render/createRenderSite.ts
@@ -41,7 +41,8 @@ type History =
  * (`app/<version>/app.js`), this run's report (`data/runs/<id>/report.json`,
  * and a copy in `runs/<id>/` for the page's report.json link), the history
  * (`data/runs.json`), and the shells (`index.html` and one
- * `runs/<id>/index.html` per run in the history), which load the app. The
+ * `runs/<id>/index.html` per run in the history), which load the app and
+ * carry this report's favicon, so the tab has its icon before the app draws. The
  * app draws each page from the data when it is viewed, so older reports are
  * never read or rewritten, and a new perfkit redraws every run.
  *
@@ -89,7 +90,10 @@ export function createRenderSite(deps: RenderSiteDeps) {
         project: merged.project,
         run,
         page,
-        perfkitVersion: deps.version
+        perfkitVersion: deps.version,
+        ...(report.project.faviconSvg
+          ? { faviconSvg: report.project.faviconSvg }
+          : {})
       });
     const at = (path: string) => join(out, ...path.split("/"));
 
diff --git a/src/render/live/renderLivePage.ts b/src/render/live/renderLivePage.ts
index 7919caa..54e4f15 100644
--- a/src/render/live/renderLivePage.ts
+++ b/src/render/live/renderLivePage.ts
@@ -4,6 +4,7 @@
 import { esc } from "../html.js";
 import { pageStyles } from "../pageStyles.js";
 import { PICKER_SCRIPT } from "../pickerScript.js";
+import { renderFaviconLink } from "../renderFaviconLink.js";
 import { liveStyles } from "./liveStyles.js";
 import { renderLiveView } from "./renderLiveView.js";
 import type { LiveViewContext } from "./types.js";
@@ -25,7 +26,7 @@ export function renderLivePage(ctx: LiveViewContext): string {
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>${esc(`${live.project.name} benchmarks · running now · v${live.version}`)}</title>
-<meta name="description" content="${esc(live.project.title)}">
+${renderFaviconLink(live.project.faviconSvg)}<meta name="description" content="${esc(live.project.title)}">
 <meta name="generator" content="perfkit ${esc(ctx.perfkitVersion)}">
 <link rel="preconnect" href="https://fonts.googleapis.com">
 <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
diff --git a/src/render/renderFaviconLink.ts b/src/render/renderFaviconLink.ts
new file mode 100644
index 0000000..040bcba
--- /dev/null
+++ b/src/render/renderFaviconLink.ts
@@ -0,0 +1,14 @@
+/**
+ * Copyright (C) 2026 by Fonoster Inc (https://fonoster.com). MIT License.
+ */
+
+/**
+ * The page head's icon link for `project.faviconSvg`, as a URL-encoded data
+ * URI and ending in a newline, or an empty string without a favicon, so a
+ * page without one is unchanged.
+ */
+export function renderFaviconLink(faviconSvg: string | undefined): string {
+  return faviconSvg
+    ? `<link rel="icon" type="image/svg+xml" href="data:image/svg+xml,${encodeURIComponent(faviconSvg)}">\n`
+    : "";
+}
diff --git a/src/render/renderRunPage.ts b/src/render/renderRunPage.ts
index ad75fd2..084d54a 100644
--- a/src/render/renderRunPage.ts
+++ b/src/render/renderRunPage.ts
@@ -3,6 +3,7 @@
  */
 import { esc } from "./html.js";
 import { pageStyles } from "./pageStyles.js";
+import { renderFaviconLink } from "./renderFaviconLink.js";
 import { PICKER_SCRIPT } from "./pickerScript.js";
 import { renderCapacitySection } from "./sections/renderCapacitySection.js";
 import { renderFooter } from "./sections/renderFooter.js";
@@ -38,7 +39,7 @@ export function renderRunPage(ctx: PageContext): string {
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>${esc(title)}</title>
-<meta name="description" content="${esc(report.project.title)}">
+${renderFaviconLink(report.project.faviconSvg)}<meta name="description" content="${esc(report.project.title)}">
 <meta name="generator" content="perfkit ${esc(ctx.perfkitVersion)}">
 <link rel="preconnect" href="https://fonts.googleapis.com">
 <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
diff --git a/src/render/renderShell.ts b/src/render/renderShell.ts
index 8d6196c..bcefab0 100644
--- a/src/render/renderShell.ts
+++ b/src/render/renderShell.ts
@@ -5,6 +5,7 @@ import type { RunEntry } from "../schemas/index.js";
 import { SITE_PATHS } from "./app/sitePaths.js";
 import { formatDate, formatTime, shortCommit } from "./format.js";
 import { esc } from "./html.js";
+import { renderFaviconLink } from "./renderFaviconLink.js";
 import type { PageKind } from "./types.js";
 import { summaryText } from "./verdicts.js";
 
@@ -21,8 +22,10 @@ export function renderShell(params: {
   run: RunEntry;
   page: PageKind;
   perfkitVersion: string;
+  /** The project's favicon, from the report being rendered. */
+  faviconSvg?: string;
 }): string {
-  const { project, run, page, perfkitVersion } = params;
+  const { project, run, page, perfkitVersion, faviconSvg } = params;
   const base = page === "latest" ? "" : "../../";
   const title = `${project} benchmarks · v${run.version}`;
   const description = `${summaryText(run.verdict)}. ${project} v${run.version}, run of ${formatDate(run.startedAt)} ${formatTime(run.startedAt)} UTC, commit ${shortCommit(run.commit)}.`;
@@ -36,7 +39,7 @@ export function renderShell(params: {
 <meta charset="utf-8">
 <meta name="viewport" content="width=device-width, initial-scale=1">
 <title>${esc(title)}</title>
-<meta name="description" content="${esc(description)}">
+${renderFaviconLink(faviconSvg)}<meta name="description" content="${esc(description)}">
 <meta property="og:type" content="website">
 <meta property="og:site_name" content="${esc(`${project} benchmarks`)}">
 <meta property="og:title" content="${esc(title)}">
diff --git a/src/render/sections/renderHistory.ts b/src/render/sections/renderHistory.ts
index 3e1040e..ff4202e 100644
--- a/src/render/sections/renderHistory.ts
+++ b/src/render/sections/renderHistory.ts
@@ -104,7 +104,7 @@ export function renderHistory(ctx: PageContext): string {
 <div>
 <p class="eyebrow">HISTORY</p>
 <h2 class="section-title" id="previous-runs">Previous runs</h2>
-<p class="section-sub">Every run keeps its own page and report.json. Open one to see it exactly as it was.</p>
+<p class="section-sub">Every run keeps its own page and report.json.</p>
 </div>
 ${trend}
 </div>
diff --git a/src/schemas/checkStepEveryMultipleOfSippInterval.ts b/src/schemas/checkStepEveryMultipleOfSippInterval.ts
new file mode 100644
index 0000000..48fdae6
--- /dev/null
+++ b/src/schemas/checkStepEveryMultipleOfSippInterval.ts
@@ -0,0 +1,29 @@
+/**
+ * Copyright (C) 2026 by Fonoster Inc (https://fonoster.com). MIT License.
+ */
+import type { z } from "zod/v4";
+import { durationSeconds } from "./durationSeconds.js";
+
+/** How often SIPp writes its statistics (`-trace_stat`), in seconds. */
+export const SIPP_STAT_INTERVAL_S = 10;
+
+/**
+ * Adds an issue at `load.rate.every` when a capacity step is not a whole
+ * number of SIPp's 10-second statistics periods: a period would then span
+ * two steps, and the step's counters would mix both rates. For use inside
+ * the capacity benchmark's `superRefine`.
+ */
+export function checkStepEveryMultipleOfSippInterval(
+  benchmark: { load: { rate: { every: string } } },
+  ctx: z.core.$RefinementCtx
+): void {
+  const { every } = benchmark.load.rate;
+  if (durationSeconds(every) % SIPP_STAT_INTERVAL_S !== 0) {
+    ctx.addIssue({
+      code: "custom",
+      path: ["load", "rate", "every"],
+      message: `expected a multiple of ${SIPP_STAT_INTERVAL_S} s (SIPp reports every ${SIPP_STAT_INTERVAL_S} s); got ${every}`,
+      input: every
+    });
+  }
+}
diff --git a/src/schemas/checkWarmupShorterThanStep.ts b/src/schemas/checkWarmupShorterThanStep.ts
index ebe44a1..d2e950a 100644
--- a/src/schemas/checkWarmupShorterThanStep.ts
+++ b/src/schemas/checkWarmupShorterThanStep.ts
@@ -2,8 +2,7 @@
  * Copyright (C) 2026 by Fonoster Inc (https://fonoster.com). MIT License.
  */
 import type { z } from "zod/v4";
-
-const UNIT_S = { s: 1, m: 60, h: 3600 } as const;
+import { durationSeconds } from "./durationSeconds.js";
 
 /**
  * Adds an issue at `warmup` when a capacity benchmark's warm-up is not
@@ -15,8 +14,8 @@ export function checkWarmupShorterThanStep(
   benchmark: { warmup: string; load: { rate: { every: string } } },
   ctx: z.core.$RefinementCtx
 ): void {
-  const warmupS = seconds(benchmark.warmup);
-  const everyS = seconds(benchmark.load.rate.every);
+  const warmupS = durationSeconds(benchmark.warmup);
+  const everyS = durationSeconds(benchmark.load.rate.every);
   if (warmupS > 0 && warmupS >= everyS) {
     ctx.addIssue({
       code: "custom",
@@ -26,8 +25,3 @@ export function checkWarmupShorterThanStep(
     });
   }
 }
-
-function seconds(duration: string): number {
-  const match = /^(\d+)([smh])$/.exec(duration);
-  return match ? Number(match[1]) * UNIT_S[match[2] as keyof typeof UNIT_S] : 0;
-}
diff --git a/src/schemas/durationSeconds.ts b/src/schemas/durationSeconds.ts
new file mode 100644
index 0000000..561f3f2
--- /dev/null
+++ b/src/schemas/durationSeconds.ts
@@ -0,0 +1,13 @@
+/**
+ * Copyright (C) 2026 by Fonoster Inc (https://fonoster.com). MIT License.
+ */
+const UNIT_S = { s: 1, m: 60, h: 3600 } as const;
+
+/**
+ * The seconds in a perfkit duration (`30s`, `5m`, `2h`), or 0 when it is not
+ * one; the schema has already rejected a bad duration by then.
+ */
+export function durationSeconds(duration: string): number {
+  const match = /^(\d+)([smh])$/.exec(duration);
+  return match ? Number(match[1]) * UNIT_S[match[2] as keyof typeof UNIT_S] : 0;
+}
diff --git a/src/schemas/perfkitConfig.schema.ts b/src/schemas/perfkitConfig.schema.ts
index ecbc80b..fa103f6 100644
--- a/src/schemas/perfkitConfig.schema.ts
+++ b/src/schemas/perfkitConfig.schema.ts
@@ -10,6 +10,7 @@
 import { z } from "zod/v4";
 import { checkUniqueIds } from "./checkUniqueIds.js";
 import { projectLiveSchema } from "./report.schema.js";
+import { checkStepEveryMultipleOfSippInterval } from "./checkStepEveryMultipleOfSippInterval.js";
 import { checkWarmupShorterThanStep } from "./checkWarmupShorterThanStep.js";
 import {
   benchmarkIdSchema,
@@ -40,6 +41,11 @@ const configProjectSchema = z.strictObject({
       error: "expected an .svg file"
     })
     .optional(),
+  favicon: relativePathSchema
+    .refine((value) => value.toLowerCase().endsWith(".svg"), {
+      error: "expected an .svg file"
+    })
+    .optional(),
   title: nonEmptyString,
   lead: nonEmptyString,
   live: projectLiveSchema.optional()
@@ -230,7 +236,8 @@ export const capacityBenchmarkConfigSchema = z
     telemetry: telemetrySchema,
     thresholds: capacityThresholdsSchema
   })
-  .superRefine(checkWarmupShorterThanStep);
+  .superRefine(checkWarmupShorterThanStep)
+  .superRefine(checkStepEveryMultipleOfSippInterval);
 
 export const soakBenchmarkConfigSchema = z.strictObject({
   id: benchmarkIdSchema,
diff --git a/src/schemas/report.schema.ts b/src/schemas/report.schema.ts
index 2b47acf..d9eab93 100644
--- a/src/schemas/report.schema.ts
+++ b/src/schemas/report.schema.ts
@@ -46,6 +46,10 @@ export const reportProjectSchema = z.strictObject({
     .string()
     .regex(/<svg[\s>]/, { error: "expected inline SVG markup" })
     .optional(),
+  faviconSvg: z
+    .string()
+    .regex(/<svg[\s>]/, { error: "expected inline SVG markup" })
+    .optional(),
   title: nonEmptyString,
   lead: nonEmptyString,
   live: projectLiveSchema.optional()
diff --git a/src/validate/checkConfigPaths.ts b/src/validate/checkConfigPaths.ts
index bcc1af2..4c724a6 100644
--- a/src/validate/checkConfigPaths.ts
+++ b/src/validate/checkConfigPaths.ts
@@ -17,6 +17,7 @@ export async function checkConfigPaths(
 ): Promise<DocumentError[]> {
   const named: Array<[string, string | undefined]> = [
     ["project.logo", config.project.logo],
+    ["project.favicon", config.project.favicon],
     ...config.benchmarks.flatMap(
       (benchmark, i): Array<[string, string | undefined]> => {
         const at = `benchmarks[${i}]`;
diff --git a/test/orchestrate/toReportProject.unit.test.ts b/test/orchestrate/toReportProject.unit.test.ts
index 4513e05..5b3966c 100644
--- a/test/orchestrate/toReportProject.unit.test.ts
+++ b/test/orchestrate/toReportProject.unit.test.ts
@@ -10,6 +10,12 @@ describe("toReportProject", () => {
     const project = toReportProject(runState());
     expect(project.name).to.equal("Routr");
     expect(project).to.not.have.property("live");
+    expect(project).to.not.have.property("faviconSvg");
+  });
+
+  it("should carry the favicon SVG when the run has one", () => {
+    const state = { ...runState(), faviconSvg: "<svg/>" };
+    expect(toReportProject(state).faviconSvg).to.equal("<svg/>");
   });
 
   it("should take project.live.url first, then live.url, then the live domain's live.json", () => {
diff --git a/test/render/createRenderSite.unit.test.ts b/test/render/createRenderSite.unit.test.ts
index 1ac3b58..1ddb249 100644
--- a/test/render/createRenderSite.unit.test.ts
+++ b/test/render/createRenderSite.unit.test.ts
@@ -86,6 +86,26 @@ describe("perfkit render", () => {
     expect(shells).to.have.length(1 + site.runs().runs.length);
   });
 
+  it("should put the report's favicon in every shell", async () => {
+    // Arrange
+    const report = loadReport("failed");
+    report.project.faviconSvg = '<svg xmlns="http://www.w3.org/2000/svg"/>';
+
+    // Act
+    const site = await renderSite(report, loadHistory(RUNS_4));
+
+    // Assert
+    const shells = [...site.written.entries()].filter(([path]) =>
+      path.endsWith("index.html")
+    );
+    expect(shells).to.have.length(1 + site.runs().runs.length);
+    shells.forEach(([, html]) =>
+      expect(html).to.contain(
+        `<link rel="icon" type="image/svg+xml" href="data:image/svg+xml,${encodeURIComponent(report.project.faviconSvg)}">`
+      )
+    );
+  });
+
   it("should print the warning and render without deltas when there is no history", async () => {
     // Act
     const result = await runRender(
diff --git a/test/render/live/renderLiveView.unit.test.ts b/test/render/live/renderLiveView.unit.test.ts
index d200b3d..4b98d17 100644
--- a/test/render/live/renderLiveView.unit.test.ts
+++ b/test/render/live/renderLiveView.unit.test.ts
@@ -193,5 +193,15 @@ describe("renderLivePage", () => {
     );
     expect($("style").text()).to.contain("prefers-reduced-motion");
     expect($("[data-picker]")).to.have.length(1);
+    expect($('link[rel="icon"]')).to.have.length(0);
+  });
+
+  it("should link the project's favicon in the head", () => {
+    const live = sampleLive(NOW - 8_000);
+    live.project = { ...live.project, faviconSvg: "<svg/>" };
+    const $ = cheerio.load(renderLivePage(ctx({ live })));
+    expect($('head link[rel="icon"]').attr("href")).to.equal(
+      `data:image/svg+xml,${encodeURIComponent("<svg/>")}`
+    );
   });
 });
diff --git a/test/render/renderFaviconLink.unit.test.ts b/test/render/renderFaviconLink.unit.test.ts
new file mode 100644
index 0000000..46c4652
--- /dev/null
+++ b/test/render/renderFaviconLink.unit.test.ts
@@ -0,0 +1,17 @@
+/**
+ * Copyright (C) 2026 by Fonoster Inc (https://fonoster.com). MIT License.
+ */
+import { expect } from "chai";
+import { renderFaviconLink } from "../../src/render/renderFaviconLink.js";
+
+describe("renderFaviconLink", () => {
+  it("should link the SVG as a URL-encoded data URI on its own line", () => {
+    expect(renderFaviconLink('<svg a="1"/>')).to.equal(
+      '<link rel="icon" type="image/svg+xml" href="data:image/svg+xml,%3Csvg%20a%3D%221%22%2F%3E">\n'
+    );
+  });
+
+  it("should be empty without a favicon", () => {
+    expect(renderFaviconLink(undefined)).to.equal("");
+  });
+});
diff --git a/test/render/renderRunPage.unit.test.ts b/test/render/renderRunPage.unit.test.ts
index 38946bf..1d5cf5a 100644
--- a/test/render/renderRunPage.unit.test.ts
+++ b/test/render/renderRunPage.unit.test.ts
@@ -567,6 +567,22 @@ describe("the report page", () => {
     expect($(".nav svg circle[fill]")).to.have.length(0);
   });
 
+  it("should link the favicon in the head, and none without one", async () => {
+    // Arrange
+    const report = loadReport("passed");
+    report.project.faviconSvg = '<svg xmlns="http://www.w3.org/2000/svg"/>';
+
+    // Act
+    const site = await renderSite(report);
+    const plain = (await renderSite(loadReport("passed"))).latest();
+
+    // Assert
+    const href = `data:image/svg+xml,${encodeURIComponent(report.project.faviconSvg)}`;
+    expect(site.latest()('head link[rel="icon"]').attr("href")).to.equal(href);
+    expect(site.runPage()('head link[rel="icon"]').attr("href")).to.equal(href);
+    expect(plain('link[rel="icon"]')).to.have.length(0);
+  });
+
   it("should fall back to the project name without a logo", async () => {
     // Arrange
     const report = loadReport("passed");
diff --git a/test/render/renderShell.unit.test.ts b/test/render/renderShell.unit.test.ts
index 9df91c1..3cfd0d4 100644
--- a/test/render/renderShell.unit.test.ts
+++ b/test/render/renderShell.unit.test.ts
@@ -83,4 +83,38 @@ describe("renderShell", () => {
       '<b>"Routr"</b> benchmarks · v2.31.5'
     );
   });
+
+  it("should link the favicon as a URL-encoded SVG data URI", () => {
+    // Act
+    const $ = load(
+      renderShell({
+        project: "Routr",
+        run,
+        page: "run",
+        perfkitVersion: "1.2.3",
+        faviconSvg: '<svg viewBox="0 0 1 1"/>'
+      })
+    );
+
+    // Assert
+    expect($('link[rel="icon"]').attr("type")).to.equal("image/svg+xml");
+    expect($('link[rel="icon"]').attr("href")).to.equal(
+      `data:image/svg+xml,${encodeURIComponent('<svg viewBox="0 0 1 1"/>')}`
+    );
+  });
+
+  it("should have no icon link without a favicon", () => {
+    // Act
+    const $ = load(
+      renderShell({
+        project: "Routr",
+        run,
+        page: "run",
+        perfkitVersion: "1.2.3"
+      })
+    );
+
+    // Assert
+    expect($('link[rel="icon"]')).to.have.length(0);
+  });
 });
diff --git a/test/schemas/durationSeconds.unit.test.ts b/test/schemas/durationSeconds.unit.test.ts
new file mode 100644
index 0000000..79e7c5a
--- /dev/null
+++ b/test/schemas/durationSeconds.unit.test.ts
@@ -0,0 +1,17 @@
+/**
+ * Copyright (C) 2026 by Fonoster Inc (https://fonoster.com). MIT License.
+ */
+import { expect } from "chai";
+import { durationSeconds } from "../../src/schemas/durationSeconds.js";
+
+describe("durationSeconds", () => {
+  it("should convert seconds, minutes and hours", () => {
+    expect(durationSeconds("15s")).to.equal(15);
+    expect(durationSeconds("2m")).to.equal(120);
+    expect(durationSeconds("1h")).to.equal(3600);
+  });
+
+  it("should return 0 for a string that is not a duration", () => {
+    expect(durationSeconds("1.5m")).to.equal(0);
+  });
+});
diff --git a/test/schemas/perfkitConfig.unit.test.ts b/test/schemas/perfkitConfig.unit.test.ts
index 11370f8..bd7a32a 100644
--- a/test/schemas/perfkitConfig.unit.test.ts
+++ b/test/schemas/perfkitConfig.unit.test.ts
@@ -87,6 +87,22 @@ describe("perfkitConfigSchema", () => {
       delete raw.project.logo;
       expect(errorsOf(perfkitConfigSchema, raw)).to.deep.equal([]);
     });
+
+    it("should accept an .svg favicon", () => {
+      const raw = loadConfig();
+      raw.project.favicon = "favicon.svg";
+      expect(perfkitConfigSchema.parse(raw).project.favicon).to.equal(
+        "favicon.svg"
+      );
+    });
+
+    it("should accept a capacity step that is a multiple of 10 s", () => {
+      const raw = loadConfig();
+      raw.benchmarks[0].load.rate.every = "30s";
+      expect(errorsOf(perfkitConfigSchema, raw)).to.deep.equal([]);
+      raw.benchmarks[0].load.rate.every = "2m";
+      expect(errorsOf(perfkitConfigSchema, raw)).to.deep.equal([]);
+    });
   });
 
   describe("with an invalid config", () => {
@@ -106,6 +122,22 @@ describe("perfkitConfigSchema", () => {
       ]);
     });
 
+    it("should reject a favicon that is not an .svg file", () => {
+      const raw = loadConfig();
+      raw.project.favicon = "favicon.png";
+      expect(errorsOf(perfkitConfigSchema, raw)).to.deep.equal([
+        "project.favicon: expected an .svg file"
+      ]);
+    });
+
+    it("should reject a capacity step that is not a multiple of 10 s", () => {
+      const raw = loadConfig();
+      raw.benchmarks[0].load.rate.every = "15s";
+      expect(errorsOf(perfkitConfigSchema, raw)).to.deep.equal([
+        "benchmarks[0].load.rate.every: expected a multiple of 10 s (SIPp reports every 10 s); got 15s"
+      ]);
+    });
+
     it("should reject a capacity warm-up as long as a step", () => {
       const raw = loadConfig();
       raw.benchmarks[0].warmup = "1m";
diff --git a/test/schemas/report.unit.test.ts b/test/schemas/report.unit.test.ts
index 7d33b40..c647f9e 100644
--- a/test/schemas/report.unit.test.ts
+++ b/test/schemas/report.unit.test.ts
@@ -32,6 +32,12 @@ describe("reportSchema", () => {
       expect(errorsOf(reportSchema, report)).to.deep.equal([]);
     });
 
+    it("should accept a report with a faviconSvg", () => {
+      const report = loadReport("passed");
+      report.project.faviconSvg = '<svg xmlns="http://www.w3.org/2000/svg"/>';
+      expect(errorsOf(reportSchema, report)).to.deep.equal([]);
+    });
+
     it("should accept a report without logoSvg, hops or otelcol", () => {
       const report = loadReport("passed");
       delete report.project.logoSvg;
@@ -42,6 +48,14 @@ describe("reportSchema", () => {
   });
 
   describe("with an invalid report", () => {
+    it("should reject a faviconSvg that is not SVG markup", () => {
+      const report = loadReport("passed");
+      report.project.faviconSvg = "favicon.svg";
+      expect(errorsOf(reportSchema, report)).to.deep.equal([
+        'project.faviconSvg: expected inline SVG markup; got "favicon.svg"'
+      ]);
+    });
+
     it('should reject verdict "ok" with the Contract\'s message', () => {
       const report = loadReport("passed");
       report.benchmarks[1].verdict = "ok";
diff --git a/test/validate/checkConfigPaths.unit.test.ts b/test/validate/checkConfigPaths.unit.test.ts
index 39bdb97..c1e7963 100644
--- a/test/validate/checkConfigPaths.unit.test.ts
+++ b/test/validate/checkConfigPaths.unit.test.ts
@@ -40,6 +40,27 @@ describe("checkConfigPaths", () => {
     );
   });
 
+  it("should check project.favicon when it is set", async () => {
+    // Arrange
+    const withFavicon = perfkitConfigSchema.parse({
+      ...loadConfig(),
+      project: { ...loadConfig().project, favicon: "favicon.svg" }
+    });
+    const isFile = sinon
+      .stub()
+      .callsFake(
+        async (path: string) => path !== resolve("/perf", "favicon.svg")
+      );
+
+    // Act
+    const errors = await checkConfigPaths(withFavicon, "/perf", isFile);
+
+    // Assert
+    expect(errors).to.deep.equal([
+      { path: "project.favicon", message: "file not found: favicon.svg" }
+    ]);
+  });
+
   it("should name the field of each missing file", async () => {
     // Arrange
     const missing = [