How do I install the Diagnose skill?

Run npx skillmds@latest add morphiaorg/diagnose in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

Is Diagnose safe to use?

This skill has not completed SkillMD's automated safety review yet. SkillMD never runs a skill's scripts for you; review the SKILL.md before installing.

Which AI agents work with Diagnose?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Diagnose free to use?

Yes. Installing skills from SkillMD is free, and the skill stays under its author's original license.

Who published Diagnose?

morphiaorg (@morphiaorg) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Diagnose by morphiaorg — Agent Skill

Name: Diagnose
Author: morphiaorg

File contents

Diagnose Test Failure

Overview

Systematic diagnosis of test failures in the Morphia project. Run the test, read the full error, trace the root cause through source and generated code, fix minimally, and verify.

Workflow

Run the failing test

./mvnw test -pl :module-name -Dtest="ClassName#methodName" -Ddeploy.skip=true

Use -Ddeploy.skip=true to skip dokka
Do NOT use -am with -Dtest= (applies test filter to all modules)

If dependencies need rebuilding first:

./mvnw install -pl :dep1,:dep2 -DskipTests -Ddeploy.skip=true -Dinvoker.skip=true

Read the full error - stack trace, error message, line numbers. Don't skip anything.
Find relevant code - Read both source AND generated code:
- Source: src/main/, src/test/
- Generated bytecode: target/test-classes/ - use javap -c -p ClassName to decompile
- Generated sources: target/generated-sources/
- Interfaces from dependencies: check ~/.m2/repository/ source jars with unzip -p
Trace the root cause - Follow the error backward:
- What method is missing/wrong?
- What generated it? (Gizmo generator? ASM generator?)
- What does the interface/superclass require?
- Compare with working examples (ASM-based generators have bridge methods; check if Gizmo-based ones do too)

Fix minimally - One change at a time. Rebuild affected modules:

./mvnw install -pl :critter-core,:critter-maven -DskipTests -Ddeploy.skip=true -Dinvoker.skip=true

Verify - Re-run the failing test AND related tests in the same class.

Common Morphia/Critter Issues

Error	Likely Cause
`AbstractMethodError`	Missing bridge methods in generated bytecode (generic interface erasure)
`Cannot checkcast to primitive`	Gizmo `checkCast` doesn't work on primitives - use `smartCast`
`Cannot convert primitive to Object`	Need boxing: `smartCast(result, wrapperType)`
`NoSuchMethodError __read/__write`	Accessor methods not generated on entity class
`ClassNotFoundException __morphia.*`	Critter code generation didn't run or class not registered

Key Gotchas

Gizmo does NOT auto-generate bridge methods for generic interfaces
Primitive types need explicit boxing/unboxing via smartCast
checkCast(Object -> wrapper) then smartCast(wrapper -> primitive) for unboxing
smartCast(primitive -> wrapper) for boxing
Always check both Gizmo (parser/gizmo/) and ASM (parser/asm/) generators for patterns

---name: diagnosedescription: Use when a test fails and you need to diagnose the root cause. Run the test, read errors, trace through generated and source code, fix, and verify.---# Diagnose Test Failure## OverviewSystematic diagnosis of test failures in the Morphia project. Run the test, read the full error, trace the root cause through source and generated code, fix minimally, and verify.## Workflow1. **Run the failing test** ``` ./mvnw test -pl :module-name -Dtest="ClassName#methodName" -Ddeploy.skip=true ``` - Use `-Ddeploy.skip=true` to skip dokka - Do NOT use `-am` with `-Dtest=` (applies test filter to all modules) - If dependencies need rebuilding first: ``` ./mvnw install -pl :dep1,:dep2 -DskipTests -Ddeploy.skip=true -Dinvoker.skip=true ```2. **Read the full error** - stack trace, error message, line numbers. Don't skip anything.3. **Find relevant code** - Read both source AND generated code: - Source: `src/main/`, `src/test/` - Generated bytecode: `target/test-classes/` - use `javap -c -p ClassName` to decompile - Generated sources: `target/generated-sources/` - Interfaces from dependencies: check `~/.m2/repository/` source jars with `unzip -p`4. **Trace the root cause** - Follow the error backward: - What method is missing/wrong? - What generated it? (Gizmo generator? ASM generator?) - What does the interface/superclass require? - Compare with working examples (ASM-based generators have bridge methods; check if Gizmo-based ones do too)5. **Fix minimally** - One change at a time. Rebuild affected modules: ``` ./mvnw install -pl :critter-core,:critter-maven -DskipTests -Ddeploy.skip=true -Dinvoker.skip=true ```6. **Verify** - Re-run the failing test AND related tests in the same class.## Common Morphia/Critter Issues| Error | Likely Cause ||-------|-------------|| `AbstractMethodError` | Missing bridge methods in generated bytecode (generic interface erasure) || `Cannot checkcast to primitive` | Gizmo `checkCast` doesn't work on primitives - use `smartCast` || `Cannot convert primitive to Object` | Need boxing: `smartCast(result, wrapperType)` || `NoSuchMethodError __read*/__write*` | Accessor methods not generated on entity class || `ClassNotFoundException __morphia.*` | Critter code generation didn't run or class not registered |## Key Gotchas- Gizmo does NOT auto-generate bridge methods for generic interfaces- Primitive types need explicit boxing/unboxing via `smartCast`- `checkCast(Object -> wrapper)` then `smartCast(wrapper -> primitive)` for unboxing- `smartCast(primitive -> wrapper)` for boxing- Always check both Gizmo (`parser/gizmo/`) and ASM (`parser/asm/`) generators for patterns

Frequently asked questions

Diagnose