diff --git a/.github/workflows/benchmarks.yml b/.github/workflows/benchmarks.yml
index 7072f32..7b40be3 100644
--- a/.github/workflows/benchmarks.yml
+++ b/.github/workflows/benchmarks.yml
@@ -48,7 +48,7 @@ jobs:
       - uses: actions/setup-java@v5
         with:
           distribution: temurin
-          java-version: "21"
+          java-version: "25"
 
       - name: Confirm Docker
         run: docker info
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2199715..81d647f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,7 +22,7 @@ jobs:
       - uses: actions/setup-java@v5
         with:
           distribution: temurin
-          java-version: "21"
+          java-version: "25"
       - uses: gradle/actions/setup-gradle@v6
         with:
           gradle-version: wrapper
@@ -73,7 +73,7 @@ jobs:
       - uses: actions/setup-java@v5
         with:
           distribution: temurin
-          java-version: "21"
+          java-version: "25"
       - uses: gradle/actions/setup-gradle@v6
         with:
           gradle-version: wrapper
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index 07ad068..928ee08 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -18,7 +18,7 @@ on:
       release_version:
         description: "Java release version. Rust and VS Code use the base semver for alpha."
         required: true
-        default: "0.1.0-alpha.2"
+        default: "0.1.0-alpha.3"
       publish_java:
         description: "Publish Java artifacts to Maven Central."
         required: true
@@ -79,7 +79,7 @@ jobs:
         uses: actions/setup-java@v5
         with:
           distribution: temurin
-          java-version: 21
+          java-version: 25
 
       - name: Setup Gradle
         uses: gradle/actions/setup-gradle@v6
@@ -186,7 +186,7 @@ jobs:
         uses: actions/setup-java@v5
         with:
           distribution: temurin
-          java-version: 21
+          java-version: 25
 
       - name: Setup Gradle
         uses: gradle/actions/setup-gradle@v6
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 97d4b59..2935819 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,16 @@ Mortar follows semantic versioning after the first public release. Before `1.0.0
 
 ## Unreleased
 
+## 0.1.0-alpha.3 - 2026-06-23
+
+- Certified the Spring Boot starter against Spring Boot 4.1.0 and Spring
+  Framework 7.0.8.
+- Raised the Java toolchain and processor source-version target to Java 25.
+- Added Foojay toolchain provisioning so Gradle can resolve the Java 25
+  toolchain when it is not already installed locally.
+- Updated the Spring Boot example and public compatibility docs for the
+  4.1.x platform line.
+
 ## 0.1.0-alpha.2 - 2026-06-23
 
 - Added a VS Code package contract check so VSIX builds fail if source files,
diff --git a/README.md b/README.md
index f47e357..62dd0b9 100644
--- a/README.md
+++ b/README.md
@@ -8,14 +8,14 @@ executes. It is not an ORM: it does not provide managed entity state, lazy
 loading, identity maps, implicit graph traversal, or repository method-name
 query derivation.
 
-Status: alpha. Java artifacts are published as `0.1.0-alpha.2`. Rust crates
+Status: alpha. Java artifacts are prepared as `0.1.0-alpha.3`. Rust crates
 and the VS Code extension are published as `0.1.0`. Mortar remains pre-`1.0`;
 APIs may still change, and production adoption should pin exact versions and
 review migration notes.
 
 ## Current Scope
 
-- Java 21 and Spring Boot 3.5.x.
+- Java 25 and Spring Boot 4.1.x.
 - PostgreSQL 16 through a dedicated PostgreSQL renderer.
 - Generated Java metamodels for annotated models.
 - Generated fixed reads: `findById` and explicit `findAll`.
@@ -93,12 +93,12 @@ Java/Spring artifacts:
 
 ```kotlin
 dependencies {
-    implementation("io.github.sequelcore:mortar-core:0.1.0-alpha.2")
-    implementation("io.github.sequelcore:mortar-dialect-postgres:0.1.0-alpha.2")
-    implementation("io.github.sequelcore:mortar-runtime-jdbc:0.1.0-alpha.2")
-    implementation("io.github.sequelcore:mortar-spring-boot-starter:0.1.0-alpha.2")
-    annotationProcessor("io.github.sequelcore:mortar-processor:0.1.0-alpha.2")
-    testImplementation("io.github.sequelcore:mortar-testkit:0.1.0-alpha.2")
+    implementation("io.github.sequelcore:mortar-core:0.1.0-alpha.3")
+    implementation("io.github.sequelcore:mortar-dialect-postgres:0.1.0-alpha.3")
+    implementation("io.github.sequelcore:mortar-runtime-jdbc:0.1.0-alpha.3")
+    implementation("io.github.sequelcore:mortar-spring-boot-starter:0.1.0-alpha.3")
+    annotationProcessor("io.github.sequelcore:mortar-processor:0.1.0-alpha.3")
+    testImplementation("io.github.sequelcore:mortar-testkit:0.1.0-alpha.3")
 }
 ```
 
diff --git a/build.gradle.kts b/build.gradle.kts
index 101a300..405f546 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -5,7 +5,7 @@ plugins {
 }
 
 group = "io.github.sequelcore"
-version = "0.1.0-alpha.2"
+version = "0.1.0-alpha.3"
 
 val junitVersion = "6.0.3"
 val assertjVersion = "3.27.7"
@@ -252,7 +252,7 @@ subprojects {
 
     extensions.configure<JavaPluginExtension> {
         toolchain {
-            languageVersion.set(JavaLanguageVersion.of(21))
+            languageVersion.set(JavaLanguageVersion.of(25))
         }
     }
 
diff --git a/docs/plan.md b/docs/plan.md
index 7eb213f..4707f38 100644
--- a/docs/plan.md
+++ b/docs/plan.md
@@ -34,6 +34,17 @@ without changing Mortar into an ORM.
 
 ## Release Recommendation
 
-Consumers need Java artifact version `0.1.0-alpha.2` for this behavior.
+Consumers need Java artifact version `0.1.0-alpha.2` for this behavior on
+Spring Boot 3.5.x. Spring Boot 4.1.x consumers should use `0.1.0-alpha.3`.
+
+## R27 Spring Boot 4.1 Platform Certification
+
+Status: Done.
+
+| Slice | Files | Verification |
+| --- | --- | --- |
+| R27.1 Spring Boot starter baseline | `java/spring-boot-starter/build.gradle.kts`, `java/spring-boot-starter/src/test/java/dev/mortar/spring/MortarSpringBootCompatibilityTest.java` | Starter tests compile and run against Spring Boot 4.1.0. |
+| R27.2 Java 25 toolchain | `build.gradle.kts`, `settings.gradle.kts`, `java/processor/src/main/java/dev/mortar/processor/MortarProcessor.java` | Java modules compile with a Java 25 toolchain; the processor declares `RELEASE_25`. |
+| R27.3 Public docs and release metadata | `README.md`, `CHANGELOG.md`, `docs/spring-boot-compatibility.md`, `docs/release.md`, `docs/roadmap.md`, `docs/spring-boot-postgres-example.md`, `.github/workflows/publish.yml` | Public docs state the Spring Boot 4.1 and Java 25 baseline for `0.1.0-alpha.3`. |
 `0.1.0-alpha.1` does not contain the JPA discovery default change or the UUID
 fixed-read helper fix.
diff --git a/docs/release.md b/docs/release.md
index 51b1500..e7e6f06 100644
--- a/docs/release.md
+++ b/docs/release.md
@@ -42,8 +42,8 @@ change must be listed in `CHANGELOG.md` and linked from release notes.
 
 Current tested compatibility envelope:
 
-- Java 21;
-- Spring Boot 3.5.x for the starter;
+- Java 25;
+- Spring Boot 4.1.x for the starter;
 - PostgreSQL 16 for PostgreSQL Testcontainers evidence;
 - PostgreSQL as the only supported starter dialect;
 - Rust stable toolchain for CLI/compiler/LSP crates.
diff --git a/docs/roadmap.md b/docs/roadmap.md
index 9cfa063..0c3f62e 100644
--- a/docs/roadmap.md
+++ b/docs/roadmap.md
@@ -10,13 +10,13 @@ readiness work. Git history remains the detailed project history.
 ## Current Status
 
 Mortar is alpha. Java artifacts are prepared for Maven Central as
-`0.1.0-alpha.2`. Rust tooling crates and the VS Code extension remain published
+`0.1.0-alpha.3`. Rust tooling crates and the VS Code extension remain published
 as `0.1.0`. The project remains pre-`1.0`; APIs may still change before a
 stable release.
 
 Supported current scope:
 
-- Java 21, Spring Boot 3.5.x, JDBC, and PostgreSQL 16 evidence.
+- Java 25, Spring Boot 4.1.x, JDBC, and PostgreSQL 16 evidence.
 - Framework-free core query model and DSL.
 - Java annotation processor for generated `Q*` metamodels.
 - Generated fixed reads for `findById` and explicit `findAll`.
@@ -50,6 +50,7 @@ Current limits:
 | R24 Public documentation and pre-release readiness | Done | Public documentation, API/Javadocs, examples, packaging dry-runs, CI/security posture, performance wording, benchmark evidence boundaries, and the first alpha publication decision are complete. |
 | R25 Formal release automation and first alpha publication | Done | Guarded release workflow added; Java artifacts, Rust crates, and VS Code extension published for the first alpha. |
 | R26 Incremental Spring/JPA adoption hardening | Done | Mortar processor discovery is explicit by default so existing Spring/JPA applications can adopt Mortar without generating metamodels for every JPA entity. UUID identifier row models compile generated fixed-read helpers. |
+| R27 Spring Boot 4.1 platform certification | Done | The Spring Boot starter compiles and tests against Spring Boot 4.1.0 and Spring Framework 7.0.8, with Java 25 toolchain certification for Java modules. |
 
 R23 retained evidence covers the reviewed Java runtime, Rust tooling/LSP, and
 VS Code editor-latency families. The durable evidence reference is the retained
@@ -150,15 +151,39 @@ choose it deliberately.
 R26 prepares Java artifact version `0.1.0-alpha.2`. Rust crates and editor
 artifacts remain at `0.1.0`.
 
+## R27: Spring Boot 4.1 Platform Certification
+
+Status: Done
+
+Purpose: align Mortar with Sequel's 2026 backend platform direction after
+Vigil's Spring Boot 4.1 certification. Mortar remains Java-first,
+SQL-transparent, and not an ORM; this slice certifies the Spring Boot adapter
+line and Java toolchain, not a broader persistence abstraction.
+
+| Slice | Status | Outcome |
+| --- | --- | --- |
+| R27.1 Spring Boot starter certification | Done | `java/spring-boot-starter` compiles and tests against Spring Boot 4.1.0 and Spring Framework 7.0.8. |
+| R27.2 Java 25 toolchain certification | Done | Java modules use a Java 25 Gradle toolchain, the processor declares `RELEASE_25`, and Foojay toolchain provisioning is enabled. |
+| R27.3 Documentation and release alignment | Done | README, compatibility docs, release policy, changelog, and the Spring Boot example state the Boot 4.1 and Java 25 baseline. |
+
+R27 prepares Java artifact version `0.1.0-alpha.3`. Rust crates and editor
+artifacts remain at `0.1.0`.
+
 ## Release Path
 
 R25 closes the first alpha publication action. Published artifacts:
 
-- Maven Central: `io.github.sequelcore:mortar-*` version `0.1.0-alpha.2`.
+- Maven Central: `io.github.sequelcore:mortar-*` version `0.1.0-alpha.1`.
 - crates.io: `sequel-mortar-compiler`, `sequel-mortar-cli`, and
   `sequel-mortar-lsp` version `0.1.0`.
 - Visual Studio Marketplace: `sequelcore.mortar-vscode` version `0.1.0`
   pre-release.
 
+Prepared Java artifacts:
+
+- `0.1.0-alpha.2` for incremental Spring/JPA adoption hardening on the Spring
+  Boot 3.5.x line.
+- `0.1.0-alpha.3` for Spring Boot 4.1.x and Java 25 platform certification.
+
 Application migration, stable API commitments, and public performance claims
 remain outside the first alpha.
diff --git a/docs/spring-boot-compatibility.md b/docs/spring-boot-compatibility.md
index b487841..be0e2d9 100644
--- a/docs/spring-boot-compatibility.md
+++ b/docs/spring-boot-compatibility.md
@@ -6,8 +6,8 @@ Mortar's Spring Boot starter follows Spring Boot's current auto-configuration mo
 
 | Spring Boot line | Status | Verification | Notes |
 | --- | --- | --- | --- |
-| 3.5.x | Tested | `java/spring-boot-starter` compiles and tests against Spring Boot 3.5.14 | Primary supported line for the current Mortar development cycle. |
-| 4.x | Planned | Not yet compiled in CI | Support requires a dedicated compatibility lane before being marked tested. |
+| 4.1.x | Tested | `java/spring-boot-starter` compiles and tests against Spring Boot 4.1.0 | Primary supported line for the current Mortar development cycle. |
+| 3.5.x | Previous alpha line | Last tested in `0.1.0-alpha.2` against Spring Boot 3.5.14 | Supported consumers should stay pinned to `0.1.0-alpha.2` until they migrate to Spring Boot 4.1.x. |
 
 ## Compatibility Rules
 
@@ -63,9 +63,10 @@ The boundary follows current platform practice:
 
 ## Current Baseline
 
-- Spring Boot autoconfigure: `3.5.14`
-- Spring Boot starter test: `3.5.14`
-- Spring Boot starter JDBC: `3.5.14`
-- Spring Boot starter Actuator: `3.5.14`
+- Spring Boot autoconfigure: `4.1.0`
+- Spring Boot starter test: `4.1.0`
+- Spring Boot starter JDBC: `4.1.0`
+- Spring Boot starter Actuator: `4.1.0`
+- Spring Framework JDBC: `7.0.8`
 
 The canonical version source is `java/spring-boot-starter/build.gradle.kts`.
diff --git a/docs/spring-boot-postgres-example.md b/docs/spring-boot-postgres-example.md
index b6fac95..2f982bc 100644
--- a/docs/spring-boot-postgres-example.md
+++ b/docs/spring-boot-postgres-example.md
@@ -6,7 +6,7 @@ For copyable repository recipes using the same patterns, see
 
 ## What It Shows
 
-- Spring Boot 3.5 wiring through `java/spring-boot-starter`.
+- Spring Boot 4.1 wiring through `java/spring-boot-starter`.
 - PostgreSQL rendering through `java/dialect-postgres`.
 - JDBC execution boundary through `MortarJdbcClient`.
 - Generated Java metamodels through `java/processor`.
diff --git a/examples/spring-boot-postgres/build.gradle.kts b/examples/spring-boot-postgres/build.gradle.kts
index db9eeff..e04f2ee 100644
--- a/examples/spring-boot-postgres/build.gradle.kts
+++ b/examples/spring-boot-postgres/build.gradle.kts
@@ -1,15 +1,17 @@
 description = "Runnable Spring Boot PostgreSQL example for Mortar."
 
+val springBootVersion = "4.1.0"
+
 dependencies {
     implementation(project(":java:spring-boot-starter"))
-    implementation("org.springframework.boot:spring-boot-starter-jdbc:3.5.14")
+    implementation("org.springframework.boot:spring-boot-starter-jdbc:$springBootVersion")
 
     compileOnly(project(":java:processor"))
     annotationProcessor(project(":java:processor"))
     runtimeOnly("org.postgresql:postgresql:42.7.11")
 
     testImplementation(project(":java:testkit"))
-    testImplementation("org.springframework.boot:spring-boot-starter-test:3.5.14")
+    testImplementation("org.springframework.boot:spring-boot-starter-test:$springBootVersion")
 }
 
 tasks.withType<JavaCompile>().configureEach {
diff --git a/java/processor/src/main/java/dev/mortar/processor/MortarProcessor.java b/java/processor/src/main/java/dev/mortar/processor/MortarProcessor.java
index 805e7d3..e957b9d 100644
--- a/java/processor/src/main/java/dev/mortar/processor/MortarProcessor.java
+++ b/java/processor/src/main/java/dev/mortar/processor/MortarProcessor.java
@@ -38,7 +38,7 @@
  */
 @SupportedAnnotationTypes("*")
 @SupportedOptions(MortarProcessor.JPA_DISCOVERY_OPTION)
-@SupportedSourceVersion(SourceVersion.RELEASE_21)
+@SupportedSourceVersion(SourceVersion.RELEASE_25)
 public final class MortarProcessor extends AbstractProcessor {
     static final String JPA_DISCOVERY_OPTION = "mortar.jpaDiscovery";
     private final List<EntityMetadata> sharedMetadata = new ArrayList<>();
diff --git a/java/processor/src/test/java/dev/mortar/processor/MortarProcessorGradleIncrementalConvergenceTest.java b/java/processor/src/test/java/dev/mortar/processor/MortarProcessorGradleIncrementalConvergenceTest.java
index 706f62a..d23c37d 100644
--- a/java/processor/src/test/java/dev/mortar/processor/MortarProcessorGradleIncrementalConvergenceTest.java
+++ b/java/processor/src/test/java/dev/mortar/processor/MortarProcessorGradleIncrementalConvergenceTest.java
@@ -99,7 +99,7 @@ private static void writeFixtureProject(Path projectDir) throws Exception {
 
                 java {
                     toolchain {
-                        languageVersion = JavaLanguageVersion.of(21)
+                        languageVersion = JavaLanguageVersion.of(25)
                     }
                 }
 
diff --git a/java/processor/src/test/java/dev/mortar/processor/MortarProcessorTest.java b/java/processor/src/test/java/dev/mortar/processor/MortarProcessorTest.java
index af4b35f..f00eaff 100644
--- a/java/processor/src/test/java/dev/mortar/processor/MortarProcessorTest.java
+++ b/java/processor/src/test/java/dev/mortar/processor/MortarProcessorTest.java
@@ -20,7 +20,7 @@ void processorDoesNotClaimRoundsYet() {
         MortarProcessor processor = new MortarProcessor();
 
         assertThat(processor.process(Set.of(), null)).isFalse();
-        assertThat(processor.getSupportedSourceVersion().name()).isEqualTo("RELEASE_21");
+        assertThat(processor.getSupportedSourceVersion().name()).isEqualTo("RELEASE_25");
     }
 
     @Test
diff --git a/java/runtime-jdbc/src/main/java/dev/mortar/jdbc/MortarJdbcLogger.java b/java/runtime-jdbc/src/main/java/dev/mortar/jdbc/MortarJdbcLogger.java
index ec87dc2..5bbf5ae 100644
--- a/java/runtime-jdbc/src/main/java/dev/mortar/jdbc/MortarJdbcLogger.java
+++ b/java/runtime-jdbc/src/main/java/dev/mortar/jdbc/MortarJdbcLogger.java
@@ -1,9 +1,9 @@
 package dev.mortar.jdbc;
 
-@FunctionalInterface
 /**
  * Logging boundary for applications that want visibility into executed SQL.
  */
+@FunctionalInterface
 public interface MortarJdbcLogger {
     void log(MortarJdbcLogEvent event);
 
diff --git a/java/spring-boot-starter/build.gradle.kts b/java/spring-boot-starter/build.gradle.kts
index d35bbb6..7717104 100644
--- a/java/spring-boot-starter/build.gradle.kts
+++ b/java/spring-boot-starter/build.gradle.kts
@@ -1,18 +1,21 @@
 description = "Spring Boot auto-configuration for Mortar."
 
+val springBootVersion = "4.1.0"
+val springFrameworkVersion = "7.0.8"
+
 dependencies {
     api(project(":java:core"))
     api(project(":java:dialect-postgres"))
     api(project(":java:runtime-jdbc"))
 
-    compileOnly("org.springframework.boot:spring-boot-autoconfigure:3.5.14")
-    compileOnly("org.springframework.boot:spring-boot-actuator-autoconfigure:3.5.14")
-    compileOnly("org.springframework:spring-jdbc:6.2.9")
-    annotationProcessor("org.springframework.boot:spring-boot-autoconfigure-processor:3.5.14")
+    compileOnly("org.springframework.boot:spring-boot-autoconfigure:$springBootVersion")
+    compileOnly("org.springframework.boot:spring-boot-actuator-autoconfigure:$springBootVersion")
+    compileOnly("org.springframework:spring-jdbc:$springFrameworkVersion")
+    annotationProcessor("org.springframework.boot:spring-boot-autoconfigure-processor:$springBootVersion")
 
-    testImplementation("org.springframework.boot:spring-boot-starter-test:3.5.14")
-    testImplementation("org.springframework.boot:spring-boot-starter-jdbc:3.5.14")
-    testImplementation("org.springframework.boot:spring-boot-starter-actuator:3.5.14")
+    testImplementation("org.springframework.boot:spring-boot-starter-test:$springBootVersion")
+    testImplementation("org.springframework.boot:spring-boot-starter-jdbc:$springBootVersion")
+    testImplementation("org.springframework.boot:spring-boot-starter-actuator:$springBootVersion")
 }
 
 tasks.withType<JavaCompile>().configureEach {
diff --git a/java/spring-boot-starter/src/test/java/dev/mortar/spring/MortarSpringBootCompatibilityTest.java b/java/spring-boot-starter/src/test/java/dev/mortar/spring/MortarSpringBootCompatibilityTest.java
index cc5ef9d..b09dd3e 100644
--- a/java/spring-boot-starter/src/test/java/dev/mortar/spring/MortarSpringBootCompatibilityTest.java
+++ b/java/spring-boot-starter/src/test/java/dev/mortar/spring/MortarSpringBootCompatibilityTest.java
@@ -7,7 +7,7 @@
 
 final class MortarSpringBootCompatibilityTest {
     @Test
-    void runsAgainstDocumentedSpringBoot35Baseline() {
-        assertThat(SpringBootVersion.getVersion()).startsWith("3.5.");
+    void runsAgainstDocumentedSpringBoot41Baseline() {
+        assertThat(SpringBootVersion.getVersion()).startsWith("4.1.");
     }
 }
diff --git a/settings.gradle.kts b/settings.gradle.kts
index 8ae6085..8243418 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -9,6 +9,7 @@ pluginManagement {
 
 plugins {
     id("org.jetbrains.intellij.platform.settings") version "2.16.0"
+    id("org.gradle.toolchains.foojay-resolver-convention") version "1.0.0"
 }
 
 dependencyResolutionManagement {