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 skills add kavo-labs/kavo --skill error-handlinggit clone --depth 1 https://github.com/kavo-labs/kavoWrote 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/skills/kavo-labs/kavo/error-handling)<a href="https://agentmods.dev/skills/kavo-labs/kavo/error-handling"><img src="https://agentmods.dev/badge/skills/kavo-labs/kavo/error-handling/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/kavo-labs/kavo/error-handling"><img src="https://agentmods.dev/badge/skills/kavo-labs/kavo/error-handling.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 2 findings, up to medium
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- medium Prompt Injection · line 42 Large whitespace padding was detected (a block of blank lines or a long run of spaces). This can push injected instructions below or to the right of the visible area so a human reviewer never sees them while the agent still reads them. Manual review of the hidden content is recommended.Fix: Remove the large whitespace padding (blank-line blocks or long space runs) and review any content hidden below or to the right of it. Keep skill files compact and reviewable so no instructions can be
- medium Excessive Agency · line 60 Skill allows unbounded resource consumption (API calls, storage, compute). Without rate limits or quotas, a compromised or misbehaving agent can cause denial-of-service or cost overruns.Fix: Set explicit rate limits, timeouts, and resource quotas for API calls, file operations, and compute. Implement circuit breakers for runaway loops.
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 5.1 | $0.00072 | $0.01573 |
| Opus 5 | $0.00036 | $0.00787 |
| Sonnet 5 | $0.00014 | $0.00315 |
| Haiku 4.5 | $0.00007 | $0.00157 |
Grade A, and why
error-handling 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 yesterday.
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 — 111 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Error handling reference
One exception hierarchy (core/src/errors/), one stable code catalog, one
wire shape (RFC 9457 problem details, ADR-0009). Full detail:
docs/internals/architecture/06-error-handling.md.
Hierarchy
KavoException (abstract; implements the KavoExceptionShape contract)
├─ QueryValidationException carries issues[] → errors[] extension
├─ NotFoundException
├─ ConflictException
├─ AlreadyDeletedException soft-deleting an already-deleted row → 409
├─ NotDeletedException restoring/purging a live row → 409
├─ OperationDisabledException
├─ OperationNotRegisteredException registry miss, never "disabled"
├─ BulkOperationException carries items[] (reserved — bulk not built)
├─ PersistenceException
├─ TransactionException carries retryable: boolean
├─ ConfigurationException bootstrap-only, never a wire response
└─ PaginationNotAdvancingException cursor page produced its own token → 500
(ADR-0021 §5); data-/adapter-dependent
Every leaf binds exactly one catalog code; status, title, and message
template all come from the catalog, so a thrown exception can never
disagree with its own documented response. @kavo/nest's
KavoExceptionFilter (@Catch(KavoException)) is the only place Kavo
touches HTTP — Kavo exceptions never extend Nest's, and core never depends
on framework exception types.
Error-code catalog (ERROR_CATALOG, core/src/errors/error-catalog.ts)
Codes are API surface — renaming one is a breaking (semver) change.
| Code | HTTP | Fires when | Payload extensions |
|---|---|---|---|
KAVO_QUERY_INVALID |
400 | Any query grammar/allowlist/limit violation (aggregate) | errors[] of the sub-codes below |
KAVO_QUERY_INVALID_FIELD |
400 | Field not on the filter/sort/select allowlist | issue-level |
KAVO_QUERY_INVALID_OPERATOR |
400 | Unknown or misspelled wire operator | issue-level |
KAVO_QUERY_INVALID_VALUE |
400 | Coercion failure, malformed bounds, bad pagination value | issue-level |
KAVO_QUERY_LIMIT_EXCEEDED |
400 | limits.filterDepth / limits.inValues exceeded |
issue-level |
KAVO_QUERY_UNSUPPORTED_PARAM |
400 | withDeleted on a hard-delete entity; include with no include resolver wired |
issue-level |
KAVO_NOT_FOUND |
404 | Target row missing on findOne/updateOne/patchOne/deleteOne |
— |
KAVO_CONFLICT |
409 | Unique/FK violation mapped by the adapter | — |
KAVO_ALREADY_DELETED |
409 | Soft-deleting an already-deleted row | — |
KAVO_NOT_DELETED |
409 | Restoring or purging a row that is not deleted | — |
KAVO_OPERATION_DISABLED |
405 | Programmatic/HTTP call to a disabled registry entry | — |
KAVO_OPERATION_NOT_REGISTERED |
405 | Programmatic call naming an operation the registry has no entry for at all | — |
KAVO_BULK_FAILED |
422 | Atomic bulk failure (reserved — bulk is not built) | items[] per-index issues |
KAVO_PERSISTENCE_FAILED |
500 | Unrecognized adapter/driver error | cause kept internally |
KAVO_TRANSACTION_FAILED |
500 | Deadlock/serialization failure | retryable flag |
KAVO_CONFIG_INVALID |
500 | Bootstrap config error — fails startup, never a response | — |
KAVO_PAGINATION_NOT_ADVANCING |
500 | Cursor page produced the token it was given; following meta.nextCursor would loop forever (ADR-0021 §5) |
— |
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.
- yesterday Changed · +3 lines ea243b396b60
- 3d ago Changed 9854887bfe6d
- 6d ago First seen · 108 lines · 72 tokens per session scan A 71e743f706a7
error-handling is a skill published in the GitHub repository kavo-labs/kavo (12 stars, last pushed today), licensed MIT. It adds 72 tokens to every session and 1,573 once invoked, about $0.0004 per session on Opus 5. 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 2026-09-02.
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