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/nerds-odd-e/doughnut/backendgit clone --depth 1 https://github.com/nerds-odd-e/doughnutWhat 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 | $0.00024 | $0.00367 |
| Opus 5 | $0.00012 | $0.00183 |
| Sonnet 5 | $0.00005 | $0.00073 |
| Haiku 4.5 | $0.00002 | $0.00037 |
Grade A, and why
backend 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 2d 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.
What it actually says
Backend
Java/Spring in backend/src/main/java/com/odde/donut/. Tests under backend/src/test/. Schema changes: db-migration.mdc.
Cursor auto-attaches backend-code.mdc (production Java) and backend-testing.mdc (tests) when matching files are in context — do not fetch them up front.
Commands
CURSOR_DEV=true nix develop -c pnpm backend:test_only
When a database migration is involved:
CURSOR_DEV=true nix develop -c pnpm backend:verify
Always run all backend unit tests, not a selected file or test case.
Production
- Controllers: return entities (or existing API body types). Narrow with
@JsonIgnore/@JsonView. Introduce a response DTO only when the wire shape differs. - Top-of-file imports. No inline fully qualified class names except when two types share a simple name.
- After Flyway schema changes, regenerate
docs/database-erd.mdwith thedatabase-erdskill (pnpm export:database-erd).
Tests
Small-test style (unit-testing.mdc): prefer controller (HTTP-stable-boundary) tests; cover services/repos via realistic makeMe preconditions and the real DB (@Transactional). Test a service/algorithm directly only when it is an intentional domain-stable contract.
Mock only external services — OpenAIClient via OpenAiStructuredResponseMock. Ownership: notebookOwnedBy(user) so trackers inherit the owner. Group with @Nested.
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.
- 2d ago First seen · 36 lines · 24 tokens per session scan A b1a2976542a1
backend is a cursor rule published in the GitHub repository nerds-odd-e/doughnut (49 stars, last pushed 2d ago), licensed MIT. It adds 24 tokens to every session and 367 once invoked, about $0.0001 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 2026-08-30.
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