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Implement @CopilotTool ergonomics#1792

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Implement @CopilotTool ergonomics#1792
edburns wants to merge 29 commits into
mainfrom
edburns/1682-java-tool-ergonomics-review-draft-01

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@edburns edburns commented Jun 24, 2026

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edburns and others added 24 commits June 24, 2026 16:51
Your branch is up to date with 'upstream/edburns/1682-java-tool-ergonomics'.

Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
	new file:   1682-java-tool-ergonomics-prompts-remove-before-merge/20260618-prompts.md

Signed-off-by: Ed Burns <edburns@microsoft.com>
- Add NONE constant to ToolDefer enum for annotation default value
- Create com.github.copilot.tool.CopilotTool annotation
- Create com.github.copilot.tool.Param annotation
- Export com.github.copilot.tool package in module-info.java
- Add CopilotToolAnnotationTest verifying retention, targets, defaults

Closes #1758
NONE is an annotation-only sentinel for @copilotTool(defer=...) defaults.
Its @jsonvalue now returns null so @JsonInclude(NON_NULL) omits it from
the JSON-RPC payload, matching the nullable/optional semantics used by
all other SDKs (.NET CopilotToolDefer?, Node defer?, Go omitempty,
Python | None, Rust Option<DeferMode>).
* WIP Phase 4.1

* Remove prompts, pre-merge

* fix(java): correct ToolDefer.NONE Javadoc on @jsonvalue null semantics

Clarify that @jsonvalue returning null does not cause field omission
by @JsonInclude(NON_NULL) — it only changes the leak from "" to null.
The primary protection is mapping NONE to a null field reference before
constructing ToolDefinition (responsibility of the annotation processor
and ToolDefinition.fromObject()).

* fix(java): address three review comments

Co-authored-by: edburns <75821+edburns@users.noreply.github.com>

* Revert "Remove prompts, pre-merge"

This reverts commit a4fe9b2.

---------

Co-authored-by: Ed Burns <edburns@microsoft.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: edburns <75821+edburns@users.noreply.github.com>
…ity (#1766)

* Initial plan

* feat(java): add SchemaGenerator compile-time type-to-JSON-Schema utility

Creates SchemaGenerator.java that maps javax.lang.model TypeMirror
instances to JSON Schema source code literals (Map.of(...) expressions).

Implements all 24 type mappings from the specification including:
- Primitives and boxed types (int/Integer, long/Long, etc.)
- String, UUID, OffsetDateTime
- Collections (List<T>, Collection<T>, Set<T>)
- Maps (Map<String, V> with typed values)
- Arrays (String[])
- Enums (with constant enumeration)
- Records and POJOs (with properties/required)
- Optional<T>, OptionalInt, OptionalDouble
- Sealed interfaces (oneOf)
- JsonNode and Object (any)

Also adds SchemaGeneratorTest using compilation-testing approach
with javax.tools.JavaCompiler to exercise the generator at compile time.

Closes #1759

* fix: address code review - remove unused param, handle all primitive types

* fix(java): correct SimpleJavaFileObject override - getCharContent not getContent

Co-authored-by: edburns <75821+edburns@users.noreply.github.com>

* spotless

* Remove .class files generated by test

* spotless

* fix: use Map.ofEntries for properties to avoid Map.of 10-entry limit

Address review comment r3461777483: Map.of() only supports up to 10
key-value pairs. Switch properties maps in SchemaGenerator to use
Map.ofEntries(Map.entry(...), ...) so records/POJOs/methods with >10
fields won't cause generated source compilation failures.

Update SchemaGeneratorTest expectations to match the new format.

* fix: add missing Byte/Short/Character boxed type mappings

Address review comment r3461777428: Byte and Short now map to
"integer", Character maps to "string", matching their primitive
equivalents. Add tests for all three.

* fix: add missing OptionalLong mapping in generateDeclaredTypeSchema

Address review comment r3461777459: OptionalLong was handled in
isOptionalType/unwrapOptional but missing from generateDeclaredTypeSchema,
causing it to fall through to POJO introspection when used as a direct
return type. Add the mapping and tests for OptionalInt, OptionalLong,
and OptionalDouble.

* fix: correct misleading @JsonSubTypes comment on sealed interface handling

Address review comment r3461777579: the implementation uses
getPermittedSubclasses() (Java sealed types), not Jackson annotations.

* test: add sealed interface test for oneOf schema generation

Address review comment r3461777685: the processor had special handling
for TestSealed* types but no test exercised generateSealedSchema().
Add a test with a sealed interface (TestSealedShape) and two record
permits (Circle, Rect) verifying the oneOf schema output.

* test: add >10-field record test proving Map.ofEntries compiles

Address review comment r3461777706: add a test with an 11-component
record that verifies the generated Map.ofEntries(...) expression
actually compiles, proving the Map.of 10-entry limit fix works
end-to-end.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: edburns <75821+edburns@users.noreply.github.com>
Co-authored-by: Ed Burns <edburns@microsoft.com>
…1777)

* Resume 1682 iterating

* Phase 03 answer questions

* On branch edburns/1682-java-tool-ergonomics
Your branch is up to date with 'upstream/edburns/1682-java-tool-ergonomics'.

Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
	new file:   1682-java-tool-ergonomics-prompts-remove-before-merge/20260618-prompts.md

Signed-off-by: Ed Burns <edburns@microsoft.com>

* WIP: Phase 3. Question 3.4

* WIP: Phase 3. Question 3.6

* WIP: Phase 3. Question 3.6: Answer

* Answer 3.7

* Resolve 3.8

* Initial plan

* feat(java): create @copilotTool and @Param annotations with tests

- Add NONE constant to ToolDefer enum for annotation default value
- Create com.github.copilot.tool.CopilotTool annotation
- Create com.github.copilot.tool.Param annotation
- Export com.github.copilot.tool package in module-info.java
- Add CopilotToolAnnotationTest verifying retention, targets, defaults

Closes #1758

* spotless

* fix(java): make ToolDefer.NONE serialize as null to prevent wire leak

NONE is an annotation-only sentinel for @copilotTool(defer=...) defaults.
Its @jsonvalue now returns null so @JsonInclude(NON_NULL) omits it from
the JSON-RPC payload, matching the nullable/optional semantics used by
all other SDKs (.NET CopilotToolDefer?, Node defer?, Go omitempty,
Python | None, Rust Option<DeferMode>).

* WIP Phase 4.1

* feat(java): create @copilotTool and @Param annotations (#1763)

* WIP Phase 4.1

* Remove prompts, pre-merge

* fix(java): correct ToolDefer.NONE Javadoc on @jsonvalue null semantics

Clarify that @jsonvalue returning null does not cause field omission
by @JsonInclude(NON_NULL) — it only changes the leak from "" to null.
The primary protection is mapping NONE to a null field reference before
constructing ToolDefinition (responsibility of the annotation processor
and ToolDefinition.fromObject()).

* fix(java): address three review comments

Co-authored-by: edburns <75821+edburns@users.noreply.github.com>

* Revert "Remove prompts, pre-merge"

This reverts commit a4fe9b2.

---------

Co-authored-by: Ed Burns <edburns@microsoft.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: edburns <75821+edburns@users.noreply.github.com>

* Initial plan

* feat(java): add SchemaGenerator compile-time type-to-JSON-Schema utility (#1766)

* Initial plan

* feat(java): add SchemaGenerator compile-time type-to-JSON-Schema utility

Creates SchemaGenerator.java that maps javax.lang.model TypeMirror
instances to JSON Schema source code literals (Map.of(...) expressions).

Implements all 24 type mappings from the specification including:
- Primitives and boxed types (int/Integer, long/Long, etc.)
- String, UUID, OffsetDateTime
- Collections (List<T>, Collection<T>, Set<T>)
- Maps (Map<String, V> with typed values)
- Arrays (String[])
- Enums (with constant enumeration)
- Records and POJOs (with properties/required)
- Optional<T>, OptionalInt, OptionalDouble
- Sealed interfaces (oneOf)
- JsonNode and Object (any)

Also adds SchemaGeneratorTest using compilation-testing approach
with javax.tools.JavaCompiler to exercise the generator at compile time.

Closes #1759

* fix: address code review - remove unused param, handle all primitive types

* fix(java): correct SimpleJavaFileObject override - getCharContent not getContent

Co-authored-by: edburns <75821+edburns@users.noreply.github.com>

* spotless

* Remove .class files generated by test

* spotless

* fix: use Map.ofEntries for properties to avoid Map.of 10-entry limit

Address review comment r3461777483: Map.of() only supports up to 10
key-value pairs. Switch properties maps in SchemaGenerator to use
Map.ofEntries(Map.entry(...), ...) so records/POJOs/methods with >10
fields won't cause generated source compilation failures.

Update SchemaGeneratorTest expectations to match the new format.

* fix: add missing Byte/Short/Character boxed type mappings

Address review comment r3461777428: Byte and Short now map to
"integer", Character maps to "string", matching their primitive
equivalents. Add tests for all three.

* fix: add missing OptionalLong mapping in generateDeclaredTypeSchema

Address review comment r3461777459: OptionalLong was handled in
isOptionalType/unwrapOptional but missing from generateDeclaredTypeSchema,
causing it to fall through to POJO introspection when used as a direct
return type. Add the mapping and tests for OptionalInt, OptionalLong,
and OptionalDouble.

* fix: correct misleading @JsonSubTypes comment on sealed interface handling

Address review comment r3461777579: the implementation uses
getPermittedSubclasses() (Java sealed types), not Jackson annotations.

* test: add sealed interface test for oneOf schema generation

Address review comment r3461777685: the processor had special handling
for TestSealed* types but no test exercised generateSealedSchema().
Add a test with a sealed interface (TestSealedShape) and two record
permits (Circle, Rect) verifying the oneOf schema output.

* test: add >10-field record test proving Map.ofEntries compiles

Address review comment r3461777706: add a test with an 11-component
record that verifies the generated Map.ofEntries(...) expression
actually compiles, proving the Map.of 10-entry limit fix works
end-to-end.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: edburns <75821+edburns@users.noreply.github.com>
Co-authored-by: Ed Burns <edburns@microsoft.com>

* WIP 4.3

* Initial plan

* feat(java): Add CopilotToolProcessor annotation processor (task 4.3)

Implements JSR 269 annotation processor that finds @CopilotTool-annotated
methods and generates $$CopilotToolMeta companion classes containing tool
definitions, JSON Schema, and invocation lambdas.

Key features:
- snake_case tool name conversion from camelCase method names
- Access level enforcement (compile error for private methods)
- Return type handling (String, void, CompletableFuture<String>, etc.)
- Argument deserialization (direct cast for primitives/String, convertValue for complex)
- @Param description and defaultValue support in schema
- ToolDefer support (NONE maps to null/regular create)
- overridesBuiltInTool and skipPermission support

Also includes comprehensive test suite using javax.tools.JavaCompiler
programmatic compilation.

Closes #1760

Co-authored-by: edburns <75821+edburns@users.noreply.github.com>

* fix: Address code review feedback

- Use fully qualified type names in generated code for type safety
- Fix Files.walk() resource leak in test with try-with-resources
- Rename exception variables for clarity

Co-authored-by: edburns <75821+edburns@users.noreply.github.com>

* fix: Fix Spotless formatting and test classpath for JDK 17

- Remove unused Collections import
- Reformat boolean expressions: && at start of continuation lines
- Reformat ternary: ? at start of continuation line
- Reformat .replace() chain with one call per line
- Fix hasErrorContaining stream method chain formatting
- Fix resolveClasspath() to use System.getProperty("java.class.path")
  first, ensuring Jackson and all test deps are available when compiling
  generated $$CopilotToolMeta code

* fix: Fix remaining Spotless violations and test classpath resolution

- Merge propertyEntries.add() onto one line per formatter requirement
- Fix sb.append() chain formatting to match Eclipse formatter output
- Revert escapeJava to original line-breaking style (formatter preference)
- Fix resolveClasspath() to combine system classpath with CodeSource
  paths from key classes (SDK, Jackson, RPC types) ensuring all
  dependencies are available for javac in the annotation processor test

* fix: Add jackson-core and jackson-annotations to test classpath

The generated 6342CopilotToolMeta code uses ObjectMapper which requires
jackson-core (Versioned, JsonFactory) and jackson-annotations at
compile time. Add these transitive dependencies to the key classes
list so their CodeSource paths are included in the javac classpath.

* fix: Fix Spotless formatting for keyClasses array initializer

* fix(java): Pass ObjectMapper as parameter in generated $$CopilotToolMeta contract

Address PR #1777 review comment (r3463252393): the generated
$$CopilotToolMeta class was using `new ObjectMapper()`, which lacks
the SDK Jackson configuration (JavaTimeModule, NON_NULL inclusion,
lenient unknown-properties). This would break tool argument coercion
and return serialization at runtime for java.time.* and other types.

Instead of embedding a bare or configured ObjectMapper in the
generated code, change the generated `definitions()` method signature
from:
    definitions(MyTools instance)
to:
    definitions(MyTools instance, ObjectMapper mapper)

This establishes an internal contract: the caller (the future
ToolDefinition.fromObject() in issue #1761) is responsible for
supplying a properly configured mapper via reflective invocation.
The generated code uses `mapper` for all convertValue() and
writeValueAsString() calls.

Benefits:
- No DRY violation (mapper config stays canonical in JsonRpcClient)
- No new public API exposing ObjectMapper
- No package-visibility workarounds
- Clean separation: generated code declares its needs, caller supplies

Issue #1761 description has been updated to document this contract
so the implementing agent knows to pass ObjectMapper as the second
argument when reflectively invoking definitions().

* fix(java): restrict single-param shortcut to records only

Address review comment on PR #1777: the isRecordOrPojo heuristic
incorrectly triggered for JDK container types (List, Map, etc.)
when used as a single tool parameter. For example, a tool with
parameter List<String> would attempt to deserialize the entire
arguments object as a List, failing at runtime.

Replace the heuristic with a deterministic check: only Java records
qualify for the getArgumentsAs() shortcut. Records are immutable
data carriers with compiler-guaranteed component lists, making them
safe for whole-object deserialization. POJOs and all other class
types now fall through to the per-field extraction path, which
always works correctly.

Removed isSimpleType() helper which was only used by the old
heuristic.

* fix(java): emit typed default values in JSON Schema

Address review comment on PR #1777: @Param(defaultValue=...) was
always emitted as a JSON string in the generated schema's 'default'
field, making numeric and boolean defaults the wrong type (e.g.,
"10" instead of 10, "true" instead of true).

Changes:
- withMeta helper: String defaultValue -> Object defaultValue
- buildPropertySchema: reuse generateDefaultLiteral() to emit typed
  Java literals (int, boolean, etc.) instead of always quoting
- Add test emitsTypedDefaultValuesInSchema verifying int -> 10,
  boolean -> true, String -> "hello" in generated code

* fix(java): fix double 61059CopilotToolMeta suffix in test helper

Address review comment on PR #1777: getGeneratedSource() fallback
search appended 61059CopilotToolMeta to a simpleName that already
contained it, producing MyTools$$CopilotToolMeta$$CopilotToolMeta.
Simplify to just match on 'class <simpleName>'.

* fix(java): use record constructor for independent flag combination

Address SDK Consistency Review on PR #1777: the if/else if chain
in writeToolDefinition silently dropped combined annotation flags
(e.g., overridesBuiltInTool + skipPermission + defer). All other
SDKs support combining these flags simultaneously.

Replace the factory method dispatch with a direct call to the
ToolDefinition record constructor, which accepts all seven fields
independently. Each flag is now emitted as its own argument:
Boolean.TRUE or null for overridesBuiltInTool/skipPermission,
ToolDefer.X or null for defer.

Add test generatesCombinedFlags verifying all three flags appear
in generated code when set together.

---------

Signed-off-by: Ed Burns <edburns@microsoft.com>
Co-authored-by: Ed Burns <edburns@microsoft.com>
Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: edburns <75821+edburns@users.noreply.github.com>
…ion API (#1779)

* Initial plan

* feat(java): Add ToolDefinition.fromObject() and fromClass() static methods

Adds static methods that load processor-generated $$CopilotToolMeta
classes and return List<ToolDefinition> with fully working tool
definitions (schema + invocation handlers).

- fromObject(Object): discovers tools from an instance with @copilotTool methods
- fromClass(Class<?>): discovers tools from a class with static @copilotTool methods
- Private getConfiguredMapper(): provides ObjectMapper matching JsonRpcClient config
- Throws IllegalStateException with helpful message if generated class not found
- Both methods annotated with @CopilotExperimental

Includes comprehensive test suite (ToolDefinitionFromObjectTest) covering:
- Basic discovery and schema verification
- Handler invocation for String, void, and CompletableFuture returns
- Argument coercion with primitives, String, boolean, and enums
- Default value handling when arguments are omitted
- Error case for missing generated class
- java.time argument deserialization (validates JavaTimeModule contract)
- Override tool flag propagation
- ToolDefer.NONE → null mapping (defer absent from JSON output)

Closes #1761

Co-authored-by: edburns <75821+edburns@users.noreply.github.com>

* fix: replace misleading generated-file comment in test fixtures

The $$CopilotToolMeta test fixtures are hand-written, not processor-
generated. Update the header comment to say so accurately.
Also fix Spotless formatting in CopilotToolProcessor.java.

Addresses PR review comment about test Javadoc inaccuracy.

* fix: introduce CopilotToolMetadataProvider interface to eliminate setAccessible

Replace reflective Method.invoke + setAccessible(true) in
ToolDefinition.loadDefinitions() with a typed interface cast.
Generated $$CopilotToolMeta classes now implement
CopilotToolMetadataProvider<T>, making them JPMS-safe and
removing the InaccessibleObjectException risk.

Addresses review comment r3468393716.

* fix: validate fromClass() rejects instance @copilotTool methods

fromClass() now scans for non-static @copilotTool methods and throws
IllegalArgumentException with an actionable message listing the
offending methods and directing users to fromObject() instead.
Prevents hard-to-diagnose NullPointerException at invocation time.

Addresses review comment r3468393764.

* fix: use parsed JSON tree for defer-absence assertion

Replace raw json.contains("defer") substring search with
ObjectNode.has("defer") to avoid false positives if another
field ever contains the substring.

Addresses review comment r3468393829.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: edburns <75821+edburns@users.noreply.github.com>
Co-authored-by: Ed Burns <edburns@microsoft.com>
…fromObject() API (#1787)

* Initial plan

* Initial plan

* Initial plan

* Add E2E integration test for ergonomic @copilotTool + ToolDefinition.fromObject() API

Create ErgonomicToolDefinitionIT that proves the ergonomic annotation-based
API produces identical wire behavior to the low-level ToolDefinition.create()
API, tested against the replay proxy.

Files added:
- test/snapshots/tools/ergonomic_tool_definition.yaml (identical to
  low_level_tool_definition.yaml since wire format is the same)
- java/src/test/java/com/github/copilot/e2e/ErgonomicToolDefinitionIT.java
- java/src/test/java/com/github/copilot/e2e/ErgonomicTestTools.java
- java/src/test/java/com/github/copilot/e2e/ErgonomicTestTools$$CopilotToolMeta.java

Closes #1762

* spotless

* fix: use passed ObjectMapper for record-parameter conversion

The single-record-parameter shortcut in CopilotToolProcessor generated
invocation.getArgumentsAs() which uses an unconfigured ObjectMapper
internally (no JavaTimeModule, no SDK settings). Switch to
mapper.convertValue(args, RecordType.class) which uses the
SDK-configured mapper passed to the definitions() method.

Addresses review comment r3469523760.

* fix: exclude Optional types from required list in generated schema

CopilotToolProcessor.generateSchemaWithParamMetadata() now checks if
a parameter type is Optional/OptionalInt/OptionalLong/OptionalDouble
before adding it to the JSON Schema required list. This aligns with
SchemaGenerator which already treats these types as optional.

Addresses review comment r3469523801.

* fix: correct misleading Javadoc in ToolDefinitionFromObjectTest

The class-level Javadoc incorrectly stated that the annotation processor
generates $$CopilotToolMeta fixtures during test compilation. In reality,
the module has <proc>none</proc> and these fixtures are hand-written
classes under com.github.copilot.rpc.fixtures.

Addresses review comment r3469523833.

* fix: remove unused grep override tool from E2E test

The ErgonomicToolDefinitionIT snapshot only exercises set_current_phase
and search_items. The grep tool (with overridesBuiltInTool=true) was
never invoked, making it dead code that contradicted the PR description.

Addresses review comment r3469523851.

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: Ed Burns <edburns@microsoft.com>
Copilot AI review requested due to automatic review settings June 24, 2026 20:59
@edburns edburns requested a review from a team as a code owner June 24, 2026 20:59
Comment thread java/src/main/java/com/github/copilot/tool/SchemaGenerator.java Fixed
Comment thread java/src/main/java/com/github/copilot/tool/SchemaGenerator.java Fixed
Comment thread java/src/main/java/com/github/copilot/tool/SchemaGenerator.java Fixed
Comment thread java/src/test/java/com/github/copilot/e2e/ErgonomicTestTools.java Fixed

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Pull request overview

This PR introduces an ergonomic, annotation-based Java tool definition API (@CopilotTool / @Param) backed by a JSR-269 annotation processor that generates $$CopilotToolMeta companion classes, enabling ToolDefinition.fromObject(...) (and fromClass(...)) to produce runnable ToolDefinition instances with generated JSON Schemas and handlers.

Changes:

  • Add @CopilotTool / @Param annotations and CopilotToolProcessor to generate tool metadata classes at compile time.
  • Add ToolDefinition.fromObject(...) / fromClass(...) runtime entry points to load generated tool definitions.
  • Add unit/processor tests plus a Java E2E snapshot + integration test to validate wire-level behavior.
Show a summary per file
File Description
test/snapshots/tools/ergonomic_tool_definition.yaml New replay snapshot for ergonomic tool definition scenario
java/src/test/java/com/github/copilot/tool/SchemaGeneratorTest.java Compilation-testing coverage for schema generator outputs
java/src/test/java/com/github/copilot/tool/CopilotToolProcessorTest.java Processor compilation tests for generated meta + validation errors
java/src/test/java/com/github/copilot/tool/CopilotToolAnnotationTest.java Annotation retention/targets/defaults verification
java/src/test/java/com/github/copilot/rpc/ToolDefinitionFromObjectTest.java E2E-style unit tests for ToolDefinition.fromObject(...) behavior
java/src/test/java/com/github/copilot/rpc/fixtures/SimpleTools$$CopilotToolMeta.java Hand-written fixture mimicking generated meta output (simple tools)
java/src/test/java/com/github/copilot/rpc/fixtures/SimpleTools.java Fixture tool class annotated with @CopilotTool / @Param
java/src/test/java/com/github/copilot/rpc/fixtures/OverrideTools$$CopilotToolMeta.java Fixture meta for override flag behavior
java/src/test/java/com/github/copilot/rpc/fixtures/OverrideTools.java Fixture tool class for override flag
java/src/test/java/com/github/copilot/rpc/fixtures/MultiReturnTools$$CopilotToolMeta.java Fixture meta for return-type handling patterns
java/src/test/java/com/github/copilot/rpc/fixtures/MultiReturnTools.java Fixture tool class for return-type handling patterns
java/src/test/java/com/github/copilot/rpc/fixtures/DefaultValueTools$$CopilotToolMeta.java Fixture meta for default parameter values
java/src/test/java/com/github/copilot/rpc/fixtures/DefaultValueTools.java Fixture tool class for default parameter values
java/src/test/java/com/github/copilot/rpc/fixtures/DateTimeTools$$CopilotToolMeta.java Fixture meta for java.time argument conversion
java/src/test/java/com/github/copilot/rpc/fixtures/DateTimeTools.java Fixture tool class using LocalDateTime parameter
java/src/test/java/com/github/copilot/rpc/fixtures/ArgCoercionTools$$CopilotToolMeta.java Fixture meta for mixed-argument coercion
java/src/test/java/com/github/copilot/rpc/fixtures/ArgCoercionTools.java Fixture tool class for mixed-argument coercion
java/src/test/java/com/github/copilot/e2e/ErgonomicToolDefinitionIT.java Failsafe IT validating end-to-end ergonomic tool usage with snapshot
java/src/test/java/com/github/copilot/e2e/ErgonomicTestTools$$CopilotToolMeta.java Hand-written E2E meta fixture mimicking processor output
java/src/test/java/com/github/copilot/e2e/ErgonomicTestTools.java Tool fixture class for E2E ergonomic test
java/src/main/resources/META-INF/services/javax.annotation.processing.Processor Registers CopilotToolProcessor as an annotation processor
java/src/main/java/module-info.java Exports com.github.copilot.tool and provides processor in module-info
java/src/main/java/com/github/copilot/tool/SchemaGenerator.java New compile-time JSON-schema source generator
java/src/main/java/com/github/copilot/tool/Param.java New @Param annotation
java/src/main/java/com/github/copilot/tool/CopilotToolProcessor.java New processor generating $$CopilotToolMeta classes
java/src/main/java/com/github/copilot/tool/CopilotToolMetadataProvider.java Contract interface for generated/manual metadata providers
java/src/main/java/com/github/copilot/tool/CopilotTool.java New @CopilotTool annotation
java/src/main/java/com/github/copilot/rpc/ToolDefinition.java Adds fromObject(...) / fromClass(...) + mapper holder
java/src/main/java/com/github/copilot/rpc/ToolDefer.java Adds NONE sentinel + serialization safety adjustments
java/mvnw Adds Maven wrapper script under java/

Copilot's findings

  • Files reviewed: 29/30 changed files
  • Comments generated: 3

Comment thread java/src/main/java/com/github/copilot/tool/SchemaGenerator.java Outdated
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edburns added 5 commits June 24, 2026 18:32
- CopilotToolProcessor.writeMetaClass: remove unused 'classElement' param
- SchemaGenerator.isOptionalType: remove unused 'typeUtils' and 'elementUtils'
- SchemaGenerator.unwrapOptional: remove unused 'elementUtils'
- ErgonomicTestTools.searchItems: use 'keyword' param in return value
The searchItems tool now includes the keyword in its response, so update
the replay proxy snapshot to expect the new format.
For static methods, the processor now generates
ClassName.method(...) instead of instance.method(...), making the
generated code clearer and avoiding compiler warnings about accessing
static members via instance references.

Adds StaticTools fixture and fromClass_staticToolInvocation test.
- LocalDateTime, Instant, ZonedDateTime → format: date-time
- LocalDate → format: date
- LocalTime → format: time

These hints tell the LLM what string format to produce for date/time
parameters. Previously only OffsetDateTime was mapped.

Adds SchemaGeneratorTest cases for each new type mapping.
The processor now generates null-check + wrapping code for Optional,
OptionalInt, OptionalLong, and OptionalDouble parameters instead of
incorrectly calling mapper.convertValue(..., Optional.class).

For Optional<T>, extracts the inner value using type-appropriate
coercion then wraps with Optional.of()/Optional.empty().
For OptionalInt/Long/Double, uses the primitive Number extraction
then wraps with the corresponding OptionalX.of()/empty().

Adds CopilotToolProcessorTest for generated code verification and
ToolDefinitionFromObjectTest for end-to-end handler invocation with
both present and absent optional values.
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Cross-SDK Consistency Review ✅

All 34 changed files in this PR are in java/ — no other SDKs are modified. I reviewed this change for cross-language feature parity and API consistency.

What this PR does

Adds annotation-based tool definition ergonomics to the Java SDK (@CopilotTool + @Param + ToolDefinition.fromObject()/fromClass()), filling a gap where Java was the only SDK without an ergonomic tool-definition API.

Cross-SDK feature parity

The new @CopilotTool annotation maps cleanly to the equivalent APIs in other SDKs:

Feature Node.js Python Go .NET Rust Java (this PR)
Ergonomic tool API defineTool() @define_tool DefineTool[T]() CopilotTool.DefineTool() ToolHandler trait @CopilotTool
overridesBuiltInTool
skipPermission
defer
Tool name override N/A N/A
Schema from types Zod/JSON Pydantic generics delegates schemars APT ✨
Parameter default in schema

Notable design decisions consistent with other SDKs

  • ToolDefer.NONE sentinel: Cleanly handles Java's annotation restriction (can't use null as a default). Maps to a null field reference before wire serialization, matching the optional defer behavior in all other SDKs (null/omitted when not specified).
  • @Param.defaultValue: Emits a "default" key in JSON Schema — consistent with how Python (Pydantic Field(default=...)), Go (jsonschema tags), and .NET (parameter defaults) all handle default values.
  • snake_case tool names: Default tool name conversion from camelCase method names matches Python's convention and is consistent with the JSON-RPC wire protocol.
  • fromObject()/fromClass() discovery: Java-idiomatic bulk discovery; equivalent to individually decorating functions in Python/Node.js.

Conclusion

This PR correctly implements Java-idiomatic tool ergonomics that achieve feature parity with the other five SDKs. All wire-format fields (overridesBuiltInTool, skipPermission, defer) are correctly mapped, and the compile-time annotation processor approach is the right Java idiom for this pattern. No cross-SDK consistency issues found.

Generated by SDK Consistency Review Agent for issue #1792 · sonnet46 1.6M ·

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4 participants