diff --git a/README.md b/README.md
index 92ed08e..9f0e39e 100644
--- a/README.md
+++ b/README.md
@@ -1,13 +1,8 @@
 # Hexis
 
-ZIO / Scala 3 SDK for [TypeSafe System One](https://docs.typesafe.ai/introduction) (Jev).
+State and questions go in. Structured answers come out.
 
-Send a state and typed questions. Get structured answers, probabilities, and confidence.
-Compose those answers in your code.
-
-Cross-built for JVM, Scala.js, and Scala Native. HTTP is [heddle](https://github.com/early-effect/heddle) 0.4.0+.
-
-Install, including the current version: [earlyeffect.rocks/hexis](https://www.earlyeffect.rocks/hexis/install.html).
+Docs: [earlyeffect.rocks/hexis](https://www.earlyeffect.rocks/hexis/)
 
 ## Quick start
 
diff --git a/build.sbt b/build.sbt
index 0c83531..8547c4e 100644
--- a/build.sbt
+++ b/build.sbt
@@ -131,8 +131,14 @@ lazy val docs = project
     specularBuildMain      := "hexis.docs.BuildSite",
     specularMetaProject    := Some(LocalProject("hexis")),
     specularArtifactKind   := "library",
-    specularSiteDirectory  := (ThisBuild / baseDirectory).value / "target" / "site",
-    specularDisplayVersion := stripCi,
+    specularSiteDirectory := (ThisBuild / baseDirectory).value / "target" / "site",
+    // Do not strip -ci first. sbt-dynver-ci names a distance build 0.1.1-ci, and stripping
+    // that suffix yields 0.1.1, which is not the published coordinate. A raw version that
+    // contains -ci, +, or SNAPSHOT advertises the last Central tag.
+    specularDisplayVersion := { raw =>
+      val distance = raw.contains("-ci") || raw.contains("+") || raw.contains("SNAPSHOT")
+      if raw.nonEmpty && !distance then raw else "0.1.0"
+    },
   )
 
 addCommandAlias("docsPreview", "~docs/specularPreview")
diff --git a/docs/src/test/scala/hexis/docs/BuildSite.scala b/docs/src/test/scala/hexis/docs/BuildSite.scala
index bd29842..a0175ae 100644
--- a/docs/src/test/scala/hexis/docs/BuildSite.scala
+++ b/docs/src/test/scala/hexis/docs/BuildSite.scala
@@ -4,36 +4,48 @@ import earlyeffect.docs.EarlyEffectTheme
 import specular.site.*
 import zio.*
 
-import java.nio.file.Path
+import java.nio.file.{Files, Path, StandardCopyOption}
 
 object BuildSite extends DocsSite:
 
-  def pages =
+  /** The guide. The front page is not in this list, so it is not a second sidebar item. */
+  private val guide: Vector[specular.DocPage] =
     Vector(Overview.doc, Install.doc, Quickstart.doc, Transport.doc, Patterns.doc, Errors.doc, Cookbooks.doc)
 
-  override def site: SiteModel =
-    val m       = meta
-    val branded = EarlyEffectTheme.brand(super.site)
+  /** Not a nav item. The sidebar is the guide; this page is the front. */
+  private val frontPage: specular.DocPage = Front.doc
+
+  def pages: Vector[specular.DocPage] = frontPage +: guide
+
+  override def site(settings: DocsSettings): SiteModel =
+    val branded = EarlyEffectTheme.brand(super.site(settings))
     branded.copy(
-      summaryMarkdown = Some(
-        """**Hexis** is a ZIO SDK for TypeSafe System One. Typed questions, structured
-answers, probabilities you can branch on. HTTP is heddle on JVM, JS, and Native.
-"""
-      ),
+      nav = Some(NavModel.flat(guide)),
+      pages = pages,
+      summaryMarkdown = None,
+      installSnippets = Vector(CodeSnippet("Install", Install.coordinate)),
       brand = Some(
         Brand(
-          name = m.title.getOrElse("hexis"),
+          name = settings.meta.displayTitle,
           links = Vector(EarlyEffectTheme.github("https://github.com/early-effect/hexis")),
         )
       ),
-      installSnippets = Vector(CodeSnippet("Install", Install.coordinate)),
     )
   end site
 
   override def layers: ZLayer[Any, Nothing, SiteBuilder] =
     EarlyEffectTheme.layers
 
-  override def afterBuild(out: Path, result: SiteOutput): Task[Unit] =
+  override def afterBuild(out: Path, result: SiteOutput): IO[SiteError, Unit] =
     val _ = result
-    EarlyEffectTheme.writeLogo(out)
+    // Specular always writes index.html as a summary plus a second copy of the nav.
+    // The front DocPage is the index. Copy it over that file. Asset paths stay site-relative.
+    val front   = out.resolve(s"${frontPage.slug}.html")
+    val index   = out.resolve("index.html")
+    val promote =
+      ZIO.attemptBlockingIO(Files.copy(front, index, StandardCopyOption.REPLACE_EXISTING)).mapError { err =>
+        SiteError.WriteFailed(index, err)
+      }
+    promote *> EarlyEffectTheme.writeLogo(out)
+  end afterBuild
 end BuildSite
diff --git a/docs/src/test/scala/hexis/docs/DocsVersion.scala b/docs/src/test/scala/hexis/docs/DocsVersion.scala
new file mode 100644
index 0000000..59bfd39
--- /dev/null
+++ b/docs/src/test/scala/hexis/docs/DocsVersion.scala
@@ -0,0 +1,18 @@
+package hexis.docs
+
+/** Install coordinate. Judge the raw build version. Do not trust a version after `-ci` was stripped. */
+object DocsVersion:
+
+  /** Last published tag. */
+  val published = "0.1.0"
+
+  /** A dynver distance (`-ci`, `+`, `SNAPSHOT`) is the next line. Anything else is advertised as written. */
+  def advertise(raw: String): String =
+    val trimmed  = raw.trim
+    val distance = trimmed.contains("-ci") || trimmed.contains("+") || trimmed.contains("SNAPSHOT")
+    if trimmed.nonEmpty && !distance then trimmed else published
+
+  /** `specular.meta.version` is the raw build version. Absent in unit tests, so those use [[published]]. */
+  def version: String =
+    sys.props.get("specular.meta.version").map(advertise).getOrElse(published)
+end DocsVersion
diff --git a/docs/src/test/scala/hexis/docs/Front.scala b/docs/src/test/scala/hexis/docs/Front.scala
new file mode 100644
index 0000000..c34b95f
--- /dev/null
+++ b/docs/src/test/scala/hexis/docs/Front.scala
@@ -0,0 +1,149 @@
+package hexis.docs
+
+import hexis.*
+import mermoid.ascent.MermoidAscent
+import mermoid.{
+  ContainerFit,
+  Diagram,
+  LayoutConfig,
+  Mermaid,
+  RenderConfig,
+  ResponsiveConfig,
+  SequenceConfig,
+  SequenceModel,
+  Viewport,
+}
+import specular.*
+import specular.ziotest.DocSpecSuite
+import zio.test.*
+
+/** The site front. Specular still emits a summary index; [[BuildSite]] copies this page over it.
+  *
+  * Not a sidebar item.
+  */
+object Front extends DocSpecSuite:
+
+  /** Caller, SystemOne, Transport, then System One. Transport is the client dependency. The remote is
+    * `POST /v1/systemone`. There is no broker.
+    */
+  private val evaluate =
+    Mermaid("""sequenceDiagram
+              |    participant Caller
+              |    participant SystemOne
+              |    participant Transport
+              |    participant API as System One
+              |    Caller->>SystemOne: state,<br/>questions
+              |    SystemOne->>Transport: POST<br/>/v1/systemone
+              |    Transport->>API: Http<br/>Request
+              |    API-->>Transport: answers
+              |    Transport-->>SystemOne: Http<br/>Response
+              |    SystemOne-->>Caller: structured<br/>answers
+              |""".stripMargin)
+
+  /** Phone column is about 390px. Fit scales down to 0.72, then the column scrolls. It does not crop the scene. */
+  private val shown =
+    RenderConfig(
+      layout = LayoutConfig(padding = 8, fontSize = 15, edgeLabelFontSize = 13, lineHeight = 18),
+      sequence = SequenceConfig(
+        actorMinWidth = 48,
+        actorPadH = 6,
+        actorHeight = 32,
+        columnGap = 12,
+        rowPitch = 34,
+        headerGap = 8,
+        footerGap = 10,
+      ),
+      responsive = ResponsiveConfig(fit = ContainerFit.ToWidth(0.72)),
+    )
+
+  private val phone = Some(Viewport(390))
+
+  def doc = page("State and questions go in. Structured answers come out.")(
+    illustration(MermoidAscent.diagram(evaluate, shown, phone)).assert { ui =>
+      val text = ui.toString
+      assertTrue(
+        text.contains("mermoid-root"),
+        text.contains("mermoid-fit"),
+        text.contains("Caller"),
+        text.contains("SystemOne"),
+        text.contains("Transport"),
+        text.contains("System One"),
+        text.contains("state,"),
+        text.contains("questions"),
+        text.contains("/v1/systemone"),
+        text.contains("Http"),
+        text.contains("Request"),
+        text.contains("Response"),
+        text.contains("structured"),
+        text.contains("answers"),
+      )
+    },
+    section("Install")(
+      md"""
+```scala
+${Install.coordinate}
+```
+"""
+    ),
+    section("SystemOne.evaluate")(
+      md"""
+`SystemOne.evaluate` is the client. The state and the questions go in. A structured answer comes out.
+""",
+      cite(
+        SystemOne.evaluate(_: String, _: Question[Boolean], _: Option[Model])(using
+          _: ToState[String],
+          _: Ask.Aux[Question[Boolean], Answer[Boolean]],
+        )
+      ),
+    ),
+  )
+
+  override def spec =
+    suite("Front")(
+      super.spec,
+      test("install coordinate is 0.1.0") {
+        val version = DocsVersion.version
+        assertTrue(
+          version == DocsVersion.published,
+          Install.coordinate.contains(version),
+          Install.coordinate.contains("%% \"hexis\""),
+          Install.coordinate.contains("%%% \"hexis\""),
+          !Install.coordinate.contains("0.1.1"),
+          !Install.coordinate.contains("-ci"),
+          !Install.coordinate.contains("SNAPSHOT"),
+          !Install.coordinate.contains("<version>"),
+          DocsVersion.advertise("0.1.1-ci") == DocsVersion.published,
+          DocsVersion.advertise("0.1.1-SNAPSHOT") == DocsVersion.published,
+          DocsVersion.advertise("0.1.0+4-abcdef") == DocsVersion.published,
+          DocsVersion.advertise("0.1.0") == "0.1.0",
+        )
+      },
+      test("the figure is evaluate, and fit keeps it inside a phone column") {
+        val order = evaluate.diagram match
+          case Diagram.Sequence(stmts) => SequenceModel.participantOrder(stmts).map(_.value)
+          case _                       => Nil
+        val ui    = MermoidAscent.diagram(evaluate, shown, phone)
+        val width = sceneWidth(ui)
+        // 0.72 is the fit floor. A 390px phone has room for about 360px of figure after page padding.
+        val fits = width.exists(w => w > 0 && w * 0.72 <= 360)
+        assertTrue(
+          order == List("Caller", "SystemOne", "Transport", "API"),
+          evaluate.source.contains("sequenceDiagram"),
+          !evaluate.source.contains("broker"),
+          fits,
+        ).label(s"scene width $width")
+      },
+    )
+
+  private def sceneWidth(ui: ascent.ast.UI[Any]): Option[Double] =
+    ui match
+      case element: ascent.ast.UI.Element[?] =>
+        val here = element.attrs.collectFirst {
+          case ascent.ast.Attr.StaticAttr("data-mermoid-width", ascent.domtypes.AttrValue.Str(raw)) =>
+            raw.toDoubleOption
+        }.flatten
+        here.orElse(element.children.iterator.map(sceneWidth).collectFirst { case Some(w) => w })
+      case ascent.ast.UI.Fragment(children) =>
+        children.iterator.map(sceneWidth).collectFirst { case Some(w) => w }
+      case _ => None
+end Front
diff --git a/docs/src/test/scala/hexis/docs/Install.scala b/docs/src/test/scala/hexis/docs/Install.scala
index 540aba6..a7e0c95 100644
--- a/docs/src/test/scala/hexis/docs/Install.scala
+++ b/docs/src/test/scala/hexis/docs/Install.scala
@@ -1,15 +1,13 @@
 package hexis.docs
 
 import specular.*
-import specular.site.ProjectMeta
 import specular.ziotest.DocSpecSuite
 import zio.test.*
 
 object Install extends DocSpecSuite:
 
-  /** Site builds pass `-Dspecular.meta.*`. Doc tests load this page without them. */
-  def docsVersion: String =
-    ProjectMeta.fromSystemProperties.map(_.docsVersion).getOrElse("0.0.0")
+  /** Site builds pass `-Dspecular.meta.version`. Doc tests load this page without it. */
+  def docsVersion: String = DocsVersion.version
 
   def coordinate: String =
     s"""libraryDependencies += "rocks.earlyeffect" %% "hexis" % "$docsVersion"
diff --git a/project/ZipxVersions.scala b/project/ZipxVersions.scala
index 5394012..3f656ef 100644
--- a/project/ZipxVersions.scala
+++ b/project/ZipxVersions.scala
@@ -21,21 +21,50 @@ object MyVersions extends ZipxVersions:
   val scalaJavaTime     = Lib("io.github.cquiroz", "scala-java-time", "2.7.0")
   val scalaJavaTimeTzdb = scalaJavaTime.mod("scala-java-time-tzdb")
 
-  val specular        = Lib("rocks.earlyeffect", "specular-core", "0.17.0")
+  val specular        = Lib("rocks.earlyeffect", "specular-core", "0.20.0")
   val specularZioTest = specular.mod("specular-zio-test").test
-  val specularTheme   = specular.mod("early-effect-docs-theme").test
-  val ascentJs        = Lib("rocks.earlyeffect", "ascent-js", "0.7.4")
-  val ascentCss       = ascentJs.mod("ascent-css")
+
+  /** Specular 0.20 depends on heddle 0.9. The published client stays on 0.4, so docs do not take that edge. */
+  val specularSite = specular
+    .mod("specular-site")
+    .excluding(
+      ZipxExclude.org("rocks.earlyeffect", "heddle_3"),
+      ZipxExclude.org("rocks.earlyeffect", "ascent-preview_3"),
+    )
+    .test
+  val specularTheme = specular
+    .mod("early-effect-docs-theme")
+    .excluding(
+      ZipxExclude.org("rocks.earlyeffect", "heddle_3"),
+      ZipxExclude.org("rocks.earlyeffect", "ascent-preview_3"),
+    )
+    .test
+
+  /** Docs figures only. The published hexis artifact does not select this. */
+  val mermoidAscent = Lib("rocks.earlyeffect", "mermoid-ascent", "0.2.0")
+
+  /** What mermoid-ascent 0.2.0 and specular 0.20 resolve. No docs client, so ascent-js stays off this classpath. */
+  val ascentCore = Lib("rocks.earlyeffect", "ascent-core", "0.10.1")
+  val ascentCss  = ascentCore.mod("ascent-css")
+  val ascentHtml = Lib("rocks.earlyeffect", "ascent-html", "0.10.0")
 
   val scalafmt       = Plugin("org.scalameta", "sbt-scalafmt", "2.6.2")
   val scalajs        = Plugin("org.scala-js", "sbt-scalajs", "1.22.0")
   val scalaNative    = Plugin("org.scala-native", "sbt-scala-native", "0.5.12")
-  val specularPlugin = Plugin("rocks.earlyeffect", "sbt-specular", "0.17.0")
+  val specularPlugin = Plugin("rocks.earlyeffect", "sbt-specular", "0.20.0")
   val sbtReload      = Plugin("com.jamesward", "sbt-reload", "0.0.7")
 
   def coreLib   = library(zio, zioStreams, zioJson, heddle)
   def coreTest  = library(zioTest, zioTestSbt)
-  def docsTest  = library(specularZioTest, specularTheme, ascentCss)
+  def docsTest  = library(
+    specularZioTest,
+    specularSite,
+    specularTheme,
+    mermoidAscent.test,
+    ascentCore,
+    ascentCss,
+    ascentHtml,
+  )
   def javaTime  = library(scalaJavaTime, scalaJavaTimeTzdb)
   def jsRuntime = javaTime
 
diff --git a/project/plugins.sbt b/project/plugins.sbt
index be11db6..ca94c45 100644
--- a/project/plugins.sbt
+++ b/project/plugins.sbt
@@ -3,5 +3,5 @@ addSbtPlugin("rocks.earlyeffect" % "sbt-zipx" % "0.18.0")
 addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.6.2")
 addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.22.0")
 addSbtPlugin("org.scala-native" % "sbt-scala-native" % "0.5.12")
-addSbtPlugin("rocks.earlyeffect" % "sbt-specular" % "0.17.0")
+addSbtPlugin("rocks.earlyeffect" % "sbt-specular" % "0.20.0")
 addSbtPlugin("com.jamesward" % "sbt-reload" % "0.0.7")