Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add rules/lsampaioweb/ai-instructions/spring-boot-exceptiongit clone --depth 1 https://github.com/lsampaioweb/ai-instructionsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/rules/lsampaioweb/ai-instructions/spring-boot-exception)<a href="https://agentmods.dev/rules/lsampaioweb/ai-instructions/spring-boot-exception"><img src="https://agentmods.dev/badge/rules/lsampaioweb/ai-instructions/spring-boot-exception.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00000 | $0.00616 |
| Opus 5 | $0.00000 | $0.00308 |
| Sonnet 5 | $0.00000 | $0.00123 |
| Haiku 4.5 | $0.00000 | $0.00062 |
Grade A, and why
spring-boot-exception scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 34 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Spring Boot Exception Engine
Naming Conventions
- Name domain exception classes with the
*Exceptionsuffix (e.g.,HolidayNotFoundException,DuplicateHolidayException). - Name exception handler classes with the
*ExceptionHandlersuffix (e.g.,HolidayExceptionHandler). - Name global advice classes with the
*Advicesuffix or*ControllerAdvicesuffix (e.g.,GlobalControllerAdvice,ApiExceptionAdvice). - Use domain-specific exception names (never
AppExceptionorCustomException).
Rules
- Use centralized exception handling for all API error responses.
- Annotate global REST exception handling classes with
@RestControllerAdvice, not@ControllerAdvice. - Define a stable error response DTO with at minimum
timestamp,status(HTTP status code),error(brief reason phrase),message(user-facing i18n text), andpath(request URI) as required fields. - Place feature-specific exception classes in the owning feature package.
- Place module-global
@RestControllerAdvice/@ControllerAdviceand shared error-envelope DTOs inshared(not undershared.exception); place other exception-related types insharedonly when two or more features share the same semantic contract. - Extend all domain exceptions from a common base exception class (e.g.,
DomainException) to enable a shared base@ExceptionHandlerand consistent HTTP status derivation. - Declare the base domain exception class as
abstract. - Embed
HttpStatusand an i18n message key in the base exception constructor; resolve the message in the handler viaMessageSource. - Map not-found failures to HTTP 404, invalid-input failures to HTTP 400, conflict failures to HTTP 409, and forbidden failures to HTTP 403.
- Add a single
@ExceptionHandlerfor the base exception type that readsex.getStatus()and resolves the user-facing message viaMessageSource. - Add
@ExceptionHandler(NoResourceFoundException.class)in the global advice to return a structured 404 error response for unmapped routes. - Keep validation-error handling distinct from domain-error handling.
- When validation failures return a different payload shape than the domain-error envelope (e.g.,
List<ValidationError>), document the intentional divergence in handler-level notes or API documentation. - Control stack trace inclusion in
ErrorResponsevia theserver.error.include-stacktraceconfiguration property.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 3d ago First seen · 34 lines · 0 tokens per session scan A 85bb0e9dabbf
spring-boot-exception is a cursor rule published in the GitHub repository lsampaioweb/ai-instructions (1 stars, last pushed 10d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 616 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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