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/jlevy/speculate/backward-compatibility-rulesgit clone --depth 1 https://github.com/jlevy/speculateWhat 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 | $0.00015 | $0.00015 |
| Opus 5 | $0.00008 | $0.00008 |
| Sonnet 5 | $0.00003 | $0.00003 |
| Haiku 4.5 | $0.00002 | $0.00002 |
Grade A, and why
backward-compatibility-rules 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.
This is a copy
100% identical to backward-compatibility-rules — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
What it actually says
../../docs/general/agent-rules/backward-compatibility-rules.md
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 · 1 lines · 15 tokens per session scan A deebb19cdb9a
backward-compatibility-rules is a cursor rule published in the GitHub repository jlevy/speculate (34 stars, last pushed 6mo ago), licensed MIT. It adds 15 tokens to every session, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to backward-compatibility-rules, differing in 0 lines, and is treated as a copy.
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