Fix composable rendered twice in fullstack SSR projects

  Generated fullstack client Main.kt called renderComposableRoot instead of hydrateComposableRoot, so the JS app appended new DOM below the
  server-rendered HTML instead of replacing it.

  - Switch generated fullstack client templates to hydrateComposableRoot
  - Clear container innerHTML in renderComposable even for SSR containers
    as a safety net against duplicates
  - Update test assertions to match new API call
  - Bump version to 0.7.0.2

Author: codeyousef

CHANGELOG.md

@@ -2,6 +2,18 @@
 
 All notable changes to this project will be documented in this file.
 
+## [0.7.0.2] - 2026-02-10
+
+### Fixed
+
+- **Composable rendered twice in fullstack SSR projects** - The server-rendered HTML and the
+  client-side app both appeared on screen because the generated client `Main.kt` used
+  `renderComposableRoot` instead of `hydrateComposableRoot`, causing the JS app to append below
+  the static SSR content rather than replacing it
+- **`renderComposable` safety net** - Calling `renderComposableRoot` on an SSR container now
+  always clears existing content before rendering, preventing duplicate output even if
+  `hydrateComposableRoot` is not used
+
 ## [0.7.0.1] - 2026-02-09
 
 ### Fixed

summon-cli/src/jvmMain/kotlin/codes/yousef/summon/cli/generators/ProjectGenerator.kt

@@ -1020,10 +1020,10 @@ fun main() {
         return """
 package ${variables["PACKAGE_NAME"]}
 
-import codes.yousef.summon.renderComposableRoot
+import codes.yousef.summon.hydrateComposableRoot
 
 fun main() {
-    renderComposableRoot("${variables["ROOT_ELEMENT_ID"]}") {
+    hydrateComposableRoot("${variables["ROOT_ELEMENT_ID"]}") {
         App()
     }
 }

summon-cli/src/jvmTest/kotlin/codes/yousef/summon/cli/generators/ProjectGeneratorTest.kt

@@ -464,7 +464,7 @@ class ProjectGeneratorTest {
         val jsBootstrap = File(tempDir, "app/src/jsMain/kotlin/com/example/full/Main.kt")
         assertTrue(jsBootstrap.exists(), "JS bootstrap should exist inside the app module")
         val jsContent = jsBootstrap.readText()
-        assertTrue(jsContent.contains("renderComposableRoot("), "JS bootstrap should use renderComposableRoot API")
+        assertTrue(jsContent.contains("hydrateComposableRoot("), "JS bootstrap should use hydrateComposableRoot API")
 
         val serverFile = File(tempDir, "backend/src/main/kotlin/com/example/full/Application.kt")
         assertTrue(serverFile.exists(), "Ktor server entrypoint should be generated in backend module")
@@ -534,8 +534,8 @@ class ProjectGeneratorTest {
             assertTrue(jsMain.exists(), "$type: JS Main.kt should exist")
             val jsContent = jsMain.readText()
             assertTrue(
-                jsContent.contains("renderComposableRoot(\"$expectedRootId\")"),
-                "$type: JS Main.kt should call renderComposableRoot(\"$expectedRootId\") but was:\n$jsContent"
+                jsContent.contains("hydrateComposableRoot(\"$expectedRootId\")"),
+                "$type: JS Main.kt should call hydrateComposableRoot(\"$expectedRootId\") but was:\n$jsContent"
             )
 
             // Generated index.html root element should match

summon-core/src/jsMain/kotlin/codes/yousef/summon/Composable.kt

@@ -1,7 +1,10 @@
 package codes.yousef.summon
 
 import codes.yousef.summon.annotation.Composable
-import codes.yousef.summon.runtime.*
+import codes.yousef.summon.runtime.LocalPlatformRenderer
+import codes.yousef.summon.runtime.PlatformRenderer
+import codes.yousef.summon.runtime.RecomposerHolder
+import codes.yousef.summon.runtime.setPlatformRenderer
 import org.w3c.dom.HTMLElement
 
 /**
@@ -29,13 +32,12 @@ fun renderComposable(renderer: PlatformRenderer, composable: @Composable () -> U
             container.getAttribute("data-ssr") == "true"
 
     if (isSSRContainer) {
-        js("console.warn('renderComposable called on SSR container - this may break hydration. Use SummonHydrationClient instead.');")
-        // Don't clear the container in SSR mode - it contains server-rendered content
-    } else {
-        // Clear container only for client-side rendering
-        container.innerHTML = ""
+        js("console.warn('renderComposable called on SSR container - use hydrateComposableRoot for hydration. Clearing SSR content to avoid duplicates.');")
     }
 
+    // Always clear the container to prevent duplicate rendering
+    container.innerHTML = ""
+
     try {
         setPlatformRenderer(renderer)
         val recomposer = RecomposerHolder.current()

version.properties

@@ -1,6 +1,6 @@
 # Centralized version information for Summon
 # This file is the single source of truth for version information
 # and is used by both the main project and example projects
-VERSION=0.7.0.1
+VERSION=0.7.0.2
 GROUP=codes.yousef
 ARTIFACT_ID=summon