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/prisma/prisma-next/no-backward-compatibilitygit clone --depth 1 https://github.com/prisma/prisma-nextWhat 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 | $0.00291 |
| Opus 5 | $0.00000 | $0.00146 |
| Sonnet 5 | $0.00000 | $0.00058 |
| Haiku 4.5 | $0.00000 | $0.00029 |
Grade A, and why
no-backward-compatibility 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 no-backward-compatibility — 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
No Backward Compatibility or Migration Paths
Rule
This project has no external consumers. Do NOT add:
- Backward compatibility code or APIs
- Migration paths or deprecation warnings
- Comments explaining "legacy" or "old" vs "new" approaches
- Test fixtures or examples showing old patterns alongside new ones
- Code comments documenting what changed or why it changed
What to Do Instead
Directly change the implementation:
- Remove old code entirely
- Update all references to use the new approach
- Update design docs to reflect the current state (not the transition)
- Update tests to only test the current approach
- Delete obsolete examples or fixtures
Rationale
Since this project has no external consumers, maintaining backward compatibility creates unnecessary complexity and technical debt. The codebase should reflect the current design, not preserve history of how it evolved.
Examples
Bad:
- Adding "legacy" codecs alongside new ones
- Keeping old test fixtures "for reference"
- Comments like "Legacy support - will be removed in future"
- Deprecation warnings or migration helpers
Good:
- Delete old code completely
- Update all references immediately
- Update design docs to show current state only
- Tests only exercise current patterns
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 · 44 lines · 0 tokens per session scan A 8d9d40c7c886
no-backward-compatibility is a cursor rule published in the GitHub repository prisma/prisma-next (420 stars, last pushed 7d ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 291 tokens. A static security scan graded it A with 0 findings. It is 100% identical to no-backward-compatibility, differing in 0 lines, and is treated as a copy.
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