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/goranerhartic/cursor-development-rules/aggregationgit clone --depth 1 https://github.com/GoranErhartic/cursor-development-rulesWhat 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 | $0.00017 | $0.00332 |
| Opus 5 | $0.00009 | $0.00166 |
| Sonnet 5 | $0.00003 | $0.00066 |
| Haiku 4.5 | $0.00002 | $0.00033 |
Grade A, and why
aggregation 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
Response Aggregation (BFF)
When
- BFF calls multiple backends and combines results; handle sequential (when one call depends on another) vs parallel (independent calls).
Sequential
- Call A, then use result to call B; combine and transform to response DTO.
- Use Resilience4j (e.g. @CircuitBreaker) on client calls; fallback for optional data (e.g. preferences) with default or empty.
Parallel
- CompletableFuture.allOf: Submit all calls;
CompletableFuture.allOf(cf1, cf2, cf3).thenApply(v -> combine(cf1.join(), cf2.join(), cf3.join())); handle timeouts and exceptions per future. - Partial failures: Use CompletableFuture.exceptionally or handle to return partial response (e.g. main data + null for failed optional); or fail fast if all required.
- Timeout: Use orTimeout on each future or overall; cancel on timeout.
Conventions
- Use RestClient or declarative client per backend; inject into aggregation service; map backend DTOs to BFF response DTOs; log and metric failures.
- Do not run blocking calls in parallel without dedicated executor if needed (RestClient is async-friendly).
Anti-Patterns
- Blocking in parallel path; no timeout; no partial failure handling when appropriate; mixing sequential and parallel incorrectly
See also: http-clients.mdc, resilience.mdc, bff-architecture.mdc
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 · 32 lines · 17 tokens per session scan A 2ae30012d972
aggregation is a cursor rule published in the GitHub repository GoranErhartic/cursor-development-rules (19 stars, last pushed 6mo ago), licensed MIT. It adds 17 tokens to every session and 332 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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