GeezerVison

A new dependency-free module for interfaces that any object can
implement without knowing about a SciJava framework, so that code
wanting only these contracts takes on the smallest possible dependency.

Contains Versioned and GenericTyped, moved out of scijava-common3, plus
Named, Identifiable and Disposable ported from SciJava Common. No
deprecated aliases are left in scijava-common3, which the repository's
current adoption level permits.

Method names are modernized rather than preserved: getIdentifier() is
now id(), and Disposable.dispose() is abstract rather than a no-op
default, since a default that does nothing means implementing the
interface proves nothing to callers. Named exposes name() only --
mutability is a separate contract, rather than a setter that throws
UnsupportedOperationException and forces every caller to feature-detect.

Deliberately omitted for now, pending a consumer:

- Locatable, whose only real content was a default implementation
  requiring common3.Classes.location, which this module cannot depend on.
- Typed, which has no consumer until the plugin layer exists, and whose
  Class<T> type() would silently satisfy GenericTyped.type() as well,
  since Class implements Type.

Both are cheap to add on demand and expensive to remove once published.

Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_013gJpzGd3ksbME4CN6Tu2ni

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ctrueden and claude committed Oct 28, 2026

commit 9084574faec63bfc61ee9dd8642293e3edf4cd92

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30 changes: 25 additions & 5 deletions 30 docs/migration-plan.md

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Expand Up		@@ -61,6 +61,17 @@ The deliverable is not a reimplementation of SJC. It is:
		acceptable for a component in wind-down.
		3. `scijava-legacy` bridges the other way (SJ3 → SJC), and is the only
		place in this repository permitted to depend on `scijava-common`.
		4. **Every component POM must pin the version of every SciJava artifact it
		consumes, transitively included.** The modules here inherit from
		`pom-scijava`, not from this repository's aggregator POM, so a version
		property that is merely absent silently resolves the last released
		artifact instead of the reactor's snapshot. Nothing enforces the "these
		versions must match across all component POMs" convention, and the failure
		is invisible until an API changes — at which point it surfaces as
		`NoSuchMethodError` or `NoClassDefFoundError` at test time, far from its
		cause. Six components were found in this state while moving interfaces into
		`scijava-spi`. An enforcer rule for this would pay for itself; it is
		listed under open decisions.

		## Current state

Expand Down Expand Up		@@ -217,11 +228,11 @@ SLF4J, used directly, as `scijava-types` and `scijava-ops-engine` already do.

		No application context required by anything in this phase.

		- `scijava-spi` (new): pure interfaces, no behavior, no dependencies —
		`Versioned`, `GenericTyped`, `Named`, `Identifiable`, `Locatable`, `Typed`,
		`Disposable`. `Versioned` and `GenericTyped` move here from `common3`, which
		retains deprecated sub-interfaces so implementors stay source-compatible.
		`common3` does not gain a transitive dependency on it.
		- `scijava-spi` (new): pure interfaces, no behavior, no dependencies.
		Done, with `Versioned`, `GenericTyped`, `Named`, `Identifiable` and
		`Disposable`. `Versioned` and `GenericTyped` moved here from `common3` and
		were not left behind as deprecated aliases, which the repository's
		current adoption level permits.
		- The test for membership: *if a class can implement it without knowing
		about any SciJava framework, it is SPI.* `Cancelable` fails that test
		(cancellation concerns a running thing — it belongs with the execution
Expand All		@@ -231,6 +242,12 @@ No application context required by anything in this phase.
		- `Named` exposes `String name()` only. Mutability is a separate contract;
		a default `setName` that throws `UnsupportedOperationException` forces
		every caller to feature-detect.
		- Deferred, pending a consumer: `Locatable`, whose only real content was
		a default implementation that needs `common3.Classes.location` — which
		this module cannot depend on; and `Typed`, which has no consumer until the
		plugin layer exists, and whose `Class<T> type()` would collide awkwardly
		with `GenericTyped.type()` returning a `Type`. Both are cheap to add when
		something needs them; neither is cheap to remove once published.
		- `scijava-common3` absorbs the remaining general utilities: `ArrayUtils`,
		`StringUtils`, `Bytes`, `DigestUtils`, `NumberUtils`, `ProcessUtils`,
		`ListUtils`, `UnitUtils`, and the non-URL parts of `FileUtils`. It stays
Expand Down Expand Up		@@ -393,4 +410,7 @@ independence and should not carry the `scijava-` prefix.
		the bridge content grows.
		- `util.Timing` and `util.TreeNode`: port or drop, pending evidence of
		downstream usage.
		- **A build-time check that every consumed SciJava artifact is version-pinned
		in the consuming POM** — see hard constraint 4. Today this is caught only by
		a full clean build after an API change.
		- `display`: what the redesigned output-presentation mechanism looks like.

8 changes: 6 additions & 2 deletions 8 docs/migration.md

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Expand Up		@@ -71,8 +71,12 @@ A dropped row is a successful outcome, not a gap.
		\| SJC class \| Replacement \| Status \|
		\| --- \| --- \| --- \|
		\| `Priority`, `Prioritized` \| `org.scijava.priority.*` \| ported \|
		\| `Versioned` \| `org.scijava.spi.Versioned` (Phase 1; currently `common3`) \| planned \|
		\| `Named`, `Identifiable`, `Locatable`, `Typed`, `Disposable` \| `org.scijava.spi.*` (Phase 1). `Named` becomes read-only — `String name()` — with mutability a separate contract \| planned \|
		\| `Versioned` \| `org.scijava.spi.Versioned` (moved out of `common3`) \| ported \|
		\| `Named` \| `org.scijava.spi.Named` — read-only `String name()`; mutability is a separate contract \| ported \|
		\| `Identifiable` \| `org.scijava.spi.Identifiable` — `getIdentifier()` is now `id()` \| ported \|
		\| `Disposable` \| `org.scijava.spi.Disposable` — `dispose()` is abstract, not a no-op default \| ported \|
		\| `Locatable` \| deferred — its only content was a default implementation needing `common3.Classes.location`, which `scijava-spi` cannot depend on \| open \|
		\| `Typed` \| deferred to the plugin layer — no consumer yet, and `Class<T> type()` collides with `GenericTyped.type()` \| open \|
		\| `Initializable` \| `scijava-context` (Phase 2) — a lifecycle hook, not an SPI contract \| planned \|
		\| `Cancelable` \| execution layer (Phase 3) — cancellation concerns a running thing \| planned \|
		\| `ItemIO` \| `org.scijava.struct.ItemIO` \| ported \|
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1 change: 1 addition & 0 deletions 1 pom.xml

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Expand Up		@@ -75,6 +75,7 @@
		<module>scijava-ops-tutorial</module>
		<module>scijava-priority</module>
		<module>scijava-progress</module>
		<module>scijava-spi</module>
		<module>scijava-struct</module>
		<module>scijava-testutil</module>
		<module>scijava-types</module>
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6 changes: 6 additions & 0 deletions 6 scijava-meta/pom.xml

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Expand Up		@@ -95,6 +95,7 @@

		<!-- Note: These versions must match across all component POMs! -->
		<scijava-common3.version>1.0.1-SNAPSHOT</scijava-common3.version>
		<scijava-spi.version>1.0.0-SNAPSHOT</scijava-spi.version>
		</properties>

		<dependencies>
Expand All		@@ -104,6 +105,11 @@
		<artifactId>scijava-common3</artifactId>
		<version>${scijava-common3.version}</version>
		</dependency>
		<dependency>
		<groupId>org.scijava</groupId>
		<artifactId>scijava-spi</artifactId>
		<version>${scijava-spi.version}</version>
		</dependency>

		<!-- Test scope dependencies -->
		<dependency>
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1 change: 1 addition & 0 deletions 1 scijava-meta/src/main/java/module-info.java

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Expand Up		@@ -31,6 +31,7 @@
		requires java.xml;

		requires org.scijava.common3;
		requires transitive org.scijava.spi;

		exports org.scijava.meta;
		}

2 changes: 1 addition & 1 deletion 2 scijava-meta/src/main/java/org/scijava/meta/Manifest.java

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Expand Up		@@ -39,7 +39,7 @@
		import java.util.jar.Attributes;

		import org.scijava.common3.Classes;
		import org.scijava.common3.Versioned;
		import org.scijava.spi.Versioned;

		/**
		* Helper class for working with JAR manifests.
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2 changes: 1 addition & 1 deletion 2 scijava-meta/src/main/java/org/scijava/meta/POM.java

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Expand Up		@@ -38,7 +38,7 @@
		import org.scijava.common3.Apps;
		import org.scijava.common3.Classes;
		import org.scijava.common3.URLs;
		import org.scijava.common3.Versioned;
		import org.scijava.spi.Versioned;

		/**
		* Helper class for working with Maven POMs.
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6 changes: 6 additions & 0 deletions 6 scijava-ops-api/pom.xml

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Expand Up		@@ -99,6 +99,7 @@
		<scijava-discovery.version>1.0.1-SNAPSHOT</scijava-discovery.version>
		<scijava-function.version>1.0.1-SNAPSHOT</scijava-function.version>
		<scijava-priority.version>1.0.1-SNAPSHOT</scijava-priority.version>
		<scijava-spi.version>1.0.0-SNAPSHOT</scijava-spi.version>
		<scijava-struct.version>1.0.1-SNAPSHOT</scijava-struct.version>
		<scijava-types.version>1.0.1-SNAPSHOT</scijava-types.version>

Expand Down Expand Up		@@ -126,6 +127,11 @@
		<artifactId>scijava-priority</artifactId>
		<version>${scijava-priority.version}</version>
		</dependency>
		<dependency>
		<groupId>org.scijava</groupId>
		<artifactId>scijava-spi</artifactId>
		<version>${scijava-spi.version}</version>
		</dependency>
		<dependency>
		<groupId>org.scijava</groupId>
		<artifactId>scijava-struct</artifactId>
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1 change: 1 addition & 0 deletions 1 scijava-ops-api/src/main/java/module-info.java

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Expand Up		@@ -31,6 +31,7 @@
		exports org.scijava.ops.api;

		requires org.scijava.common3;
		requires transitive org.scijava.spi;
		requires org.scijava.function;
		requires transitive org.scijava.priority;
		requires transitive org.scijava.struct;
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2 changes: 1 addition & 1 deletion 2 scijava-ops-api/src/main/java/org/scijava/ops/api/OpEnvironment.java

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Expand Up		@@ -333,7 +333,7 @@ default OpBuilder op(final String opName, final Hints hints) {
		* contract of the stated {@code opType}.
		* @return An enriched version of the lambda object that embeds knowledge of
		* its generic type by implementing the
		* {@link org.scijava.common3.GenericTyped} interface.
		* {@link org.scijava.spi.GenericTyped} interface.
		*/
		<T> T typeLambda(Nil<T> opType, T lambda);

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2 changes: 1 addition & 1 deletion 2 scijava-ops-api/src/main/java/org/scijava/ops/api/OpInstance.java

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Expand Up		@@ -32,7 +32,7 @@
		import java.lang.reflect.Type;
		import java.util.Objects;

		import org.scijava.common3.GenericTyped;
		import org.scijava.spi.GenericTyped;

		/**
		* An instance of an {@link OpInfo}. They can be constructed directly, but are
Expand Down

2 changes: 1 addition & 1 deletion 2 scijava-ops-api/src/main/java/org/scijava/ops/api/RichOp.java

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Expand Up		@@ -31,7 +31,7 @@

		import java.lang.reflect.Type;

		import org.scijava.common3.GenericTyped;
		import org.scijava.spi.GenericTyped;

		/**
		* An {@link OpInstance} with state
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6 changes: 6 additions & 0 deletions 6 scijava-ops-engine/pom.xml

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Expand Up		@@ -127,6 +127,7 @@
		<scijava-ops-spi.version>1.0.1-SNAPSHOT</scijava-ops-spi.version>
		<scijava-priority.version>1.0.1-SNAPSHOT</scijava-priority.version>
		<scijava-progress.version>1.0.1-SNAPSHOT</scijava-progress.version>
		<scijava-spi.version>1.0.0-SNAPSHOT</scijava-spi.version>
		<scijava-struct.version>1.0.1-SNAPSHOT</scijava-struct.version>
		<scijava-taglets.version>1.0.1-SNAPSHOT</scijava-taglets.version>
		<scijava-testutil.version>1.0.1-SNAPSHOT</scijava-testutil.version>
Expand Down Expand Up		@@ -184,6 +185,11 @@
		<artifactId>scijava-progress</artifactId>
		<version>${scijava-progress.version}</version>
		</dependency>
		<dependency>
		<groupId>org.scijava</groupId>
		<artifactId>scijava-spi</artifactId>
		<version>${scijava-spi.version}</version>
		</dependency>
		<dependency>
		<groupId>org.scijava</groupId>
		<artifactId>scijava-struct</artifactId>
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1 change: 1 addition & 0 deletions 1 scijava-ops-engine/src/main/java/module-info.java

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Expand Up		@@ -35,6 +35,7 @@
		requires java.compiler;

		requires org.scijava.common3;
		requires org.scijava.spi;
		requires org.scijava.collections;
		requires org.scijava.discovery;
		requires org.scijava.function;
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2 changes: 1 addition & 1 deletion 2 scijava-ops-engine/src/main/java/org/scijava/ops/engine/impl/LambdaTypeBaker.java

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Expand Up		@@ -34,7 +34,7 @@
		import java.lang.reflect.Modifier;
		import java.lang.reflect.Type;

		import org.scijava.common3.GenericTyped;
		import org.scijava.spi.GenericTyped;
		import org.scijava.common3.Types;

		import javassist.CannotCompileException;
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2 changes: 1 addition & 1 deletion 2 scijava-ops-engine/src/test/java/org/scijava/ops/engine/impl/LambdaTypeBakerTest.java

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Expand Up		@@ -34,7 +34,7 @@

		import org.junit.jupiter.api.Assertions;
		import org.junit.jupiter.api.Test;
		import org.scijava.common3.GenericTyped;
		import org.scijava.spi.GenericTyped;
		import org.scijava.types.Nil;

		public class LambdaTypeBakerTest {
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2 changes: 1 addition & 1 deletion 2 scijava-ops-engine/src/test/java/org/scijava/ops/engine/matcher/OpWrappersTest.java

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Expand Up		@@ -47,7 +47,7 @@
		import org.scijava.ops.api.OpBuilder;
		import org.scijava.ops.engine.AbstractTestEnvironment;
		import org.scijava.ops.engine.OpBuilderTestOps;
		import org.scijava.common3.GenericTyped;
		import org.scijava.spi.GenericTyped;
		import org.scijava.types.Nil;

		/**
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130 changes: 130 additions & 0 deletions 130 scijava-spi/pom.xml

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		@@ -0,0 +1,130 @@
		<?xml version="1.0" encoding="UTF-8"?>
		<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
		<modelVersion>4.0.0</modelVersion>

		<parent>
		<groupId>org.scijava</groupId>
		<artifactId>pom-scijava</artifactId>
		<version>44.0.0</version>
		<relativePath />
		</parent>

		<artifactId>scijava-spi</artifactId>
		<version>1.0.0-SNAPSHOT</version>

		<name>SciJava SPI</name>
		<description>Minimal interfaces implementable by any SciJava-friendly object.</description>
		<url>https://github.com/scijava/scijava</url>
		<inceptionYear>2026</inceptionYear>
		<organization>
		<name>SciJava</name>
		<url>https://scijava.org/</url>
		</organization>
		<licenses>
		<license>
		<name>Simplified BSD License</name>
		<distribution>repo</distribution>
		</license>
		</licenses>

		<developers>
		<developer>
		<id>ctrueden</id>
		<name>Curtis Rueden</name>
		<roles>
		<role>founder</role>
		<role>lead</role>
		<role>reviewer</role>
		<role>support</role>
		<role>maintainer</role>
		</roles>
		</developer>
		<developer>
		<id>gselzer</id>
		<name>Gabriel Selzer</name>
		<roles>
		<role>founder</role>
		<role>debugger</role>
		<role>reviewer</role>
		<role>support</role>
		</roles>
		</developer>
		</developers>
		<contributors>
		<contributor>
		<name>Johannes Schindelin</name>
		<properties><id>dscho</id></properties>
		</contributor>
		</contributors>

		<mailingLists>
		<mailingList>
		<name>Image.sc Forum</name>
		<archive>https://forum.image.sc/tag/scijava</archive>
		</mailingList>
		</mailingLists>

		<scm>
		<connection>scm:git:https://github.com/scijava/scijava</connection>
		<developerConnection>scm:git:[email protected]:scijava/scijava</developerConnection>
		<tag>HEAD</tag>
		<url>https://github.com/scijava/scijava</url>
		</scm>
		<issueManagement>
		<system>GitHub Issues</system>
		<url>https://github.com/scijava/scijava/issues</url>
		</issueManagement>
		<ciManagement>
		<system>GitHub Actions</system>
		<url>https://github.com/scijava/scijava/actions</url>
		</ciManagement>

		<properties>
		<package-name>org.scijava.spi</package-name>

		<license.licenseName>bsd_2</license.licenseName>
		<license.copyrightOwners>SciJava developers.</license.copyrightOwners>
		</properties>

		<dependencies>
		<!-- No dependencies allowed! -->

		<!-- Test scope dependencies -->
		<dependency>
		<groupId>org.junit.jupiter</groupId>
		<artifactId>junit-jupiter-api</artifactId>
		<scope>test</scope>
		</dependency>
		</dependencies>

		<build>
		<plugins>
		<plugin>
		<artifactId>maven-enforcer-plugin</artifactId>
		<executions>
		<execution>
		<id>enforce-package-rules</id>
		<goals>
		<goal>enforce</goal>
		</goals>
		<phase>test</phase>
		<configuration>
		<rules>
		<NoPackageCyclesRule implementation="org.scijava.maven.plugin.enforcer.NoPackageCyclesRule" />
		<NoSubpackageDependenceRule implementation="org.scijava.maven.plugin.enforcer.NoSubpackageDependenceRule" />
		</rules>
		</configuration>
		</execution>
		</executions>
		</plugin>
		<plugin>
		<artifactId>maven-javadoc-plugin</artifactId>
		<configuration>
		<links>
		<link>https://javadoc.scijava.org/Java11/</link>
		</links>
		</configuration>
		</plugin>
		</plugins>
		</build>
		</project>

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