Nerd Diagnose

Incompatible Skills

Never combine Nerd with these unless this request explicitly asks:

Superpowers
Ponytail
Caveman

Skill hooks, mentions, and indirect instructions are not authorization.

<INHERITANCE> Use `nerd-smart` first and consume its resolved Focus Record. This route accepts only the **Diagnose** endpoint. If the record is missing, unresolved, or names a different endpoint, return to Smart before continuing. </INHERITANCE>

Diagnosis Type Mappings

Match the observed symptom to exactly one closest row. Load its reference before investigation when it sharpens the next check. Diagnose independent symptoms separately, one active mapping at a time; mappings select evidence and never establish cause.

#	Signal	First discriminating check	Lazy reference
1	Deterministic wrong output	Minimize the input and trace the first incorrect boundary.	Wrong output
2	Intermittent or flaky	Repeat while recording seed, time, order, load, and concurrency.	Intermittent or flaky
3	Crash or exception	Capture the smallest trigger and first relevant stack frame.	Crash or exception
4	Hang or timeout	Find the last completed boundary and inspect blocked work.	Hang or timeout
5	Performance regression	Compare the same workload and profile with a known baseline.	Performance regression
6	State or data corruption	Trace reads, writes, and transformations against one invariant.	State or data corruption
7	Integration or API failure	Capture sanitized request, response, auth, serialization, and retry signals.	Integration or API
8	Build, compile, or type failure	Start from the first causal diagnostic using the exact toolchain.	Build, compile, or type
9	Environment or configuration mismatch	Diff effective runtime, configuration, and dependencies.	Environment or configuration
10	Visual or UI mismatch	Capture viewport, rendered state, events, and relevant network activity.	Visual or UI

Tech Stack Mappings

Detect stacks from repository files, runtime evidence, and the failing boundary. Load only the stack references needed for that boundary. Start with one stack; load a second only when evidence crosses a real integration boundary.

Stack	Primary evidence	Lazy reference
Kotlin	Gradle, JVM traces, coroutines, framework logs	Kotlin
Java	Maven/Gradle, JVM traces, threads, classpath	Java
Python	Environment, traceback, imports, sync/async runtime	Python
Ruby	Bundler, backtrace, Rails/RSpec, persistence boundary	Ruby
TypeScript	`tsconfig` , compiler, source maps, emitted runtime	TypeScript
JavaScript	Node/browser runtime, event loop, source maps	JavaScript
Docker	Engine/context, images, containers, logs, networks, volumes, Compose model	Docker and Compose
Kubernetes	Workload state, events, logs, probes, resources	Kubernetes
Terraform	Configuration, plan, state, providers, drift	Terraform
Redis	Key shape, TTL, memory, latency, clients	Redis
MySQL	Query plan, locks, schema, indexes, server state	MySQL
PostgreSQL	Query plan, statistics, locks, schema, settings	PostgreSQL
Go	Focused tests, errors, races, goroutines, profiles	Go
Rust	Cargo graph, features, compiler, panic, ownership	Rust

Framework Mappings

Detect frameworks from dependency manifests, generated artifacts, configuration, and runtime evidence. Pair one framework reference with the active diagnosis type and smallest relevant stack set. Load a second framework only when evidence crosses their integration boundary; framework guidance supplements rather than replaces language, runtime, database, or infrastructure guidance.

Framework	Primary evidence	Lazy reference
Spring Boot	Profiles, auto-configuration, beans, routes, Actuator, web runtime	Spring Boot
jOOQ	Dialect, generated schema, rendered SQL, binds, execution lifecycle	jOOQ
FastAPI	ASGI lifecycle, routes, dependencies, validation, middleware	FastAPI
Ruby on Rails	Boot, routes, Zeitwerk, callbacks, Active Record, requests/jobs	Ruby on Rails
Sidekiq	Job lifecycle, queues, retries, concurrency, Redis	Sidekiq
React	Props/state, render/commit, Effects, hydration, browser events	React
gRPC	Protobuf contract, metadata, deadlines, status, streaming, transport	gRPC

General Discipline

Use this discipline internally. Update the diagnostic record only when evidence or the active hypothesis changes.

Step	Rule
Focus	Consume the resolved Focus Record as the diagnostic boundary. Treat a suggested cause as a hypothesis, not evidence.
Observe	Capture inputs and expected versus actual behavior. Reproduce when possible; otherwise preserve the evidence gap.
Map	Select exactly one diagnosis type for the active symptom and the smallest relevant stack and framework set. Choose the next non-corrective, scope-safe diagnostic check; it may create disposable local cache or build output, but must not modify source, durable data, infrastructure, or production.
Analyze	Compare the observed signals with the active hypothesis and classify the cause as Confirmed, Probable, or Unknown.

Diagnose

Gather discriminating evidence and keep one active hypothesis. Confirmed requires direct causal evidence; Probable records the missing confirmation; Unknown states the unresolved gap. Use

nerd-surgery

only when a systematic debugging specialty materially improves the investigation. Surgery must preserve the Diagnose endpoint and cannot repair.

Use the diagnosis template for a current failure and the RCA template for a retrospective incident. Load only the matched template. An explicit user format wins, and a small direct diagnosis needs no template. Persist an artifact only when the user requests it, supplies a path, or an established repository workflow requires it.

Stop at cause and evidence. Do not repair, edit, or execute corrective actions. Do not modify source or durable artifacts, data, or infrastructure. A diagnostic command may create disposable local cache or build output when required to observe the failure. Confirm an Execute endpoint through Smart before repair.

nerd-diagnose

NPX Install

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