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.
git clone --depth 1 https://github.com/MannanSaood/termiWrote 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/rules/mannansaood/termi/40-vfs-saf-architecture)<a href="https://agentmods.dev/rules/mannansaood/termi/40-vfs-saf-architecture"><img src="https://agentmods.dev/badge/rules/mannansaood/termi/40-vfs-saf-architecture/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/rules/mannansaood/termi/40-vfs-saf-architecture"><img src="https://agentmods.dev/badge/rules/mannansaood/termi/40-vfs-saf-architecture.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00000 | $0.00812 |
| Opus 5 | $0.00000 | $0.00406 |
| Sonnet 5 | $0.00000 | $0.00162 |
| Haiku 4.5 | $0.00000 | $0.00081 |
Grade A, and why
40-vfs-saf-architecture 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 9d 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.
How it starts
The opening of the file, as written. The whole thing — 70 lines — stays where its author put it; the contents beside it link to each section on GitHub.
VFS / SAF Capability System
This is the actual product differentiator (see docs/PHASE1_STATUS.md and
the project's strategic report) — treat changes here with more care than
elsewhere in the codebase.
The three-layer design
capabilities.rsanswers "is operation X supported on filesystem type Y, and why/why not" as pure data — no I/O, no provider awareness.provider.rsanswers "how do I actually perform operation X" for a specific backend. Its trait defaults assume an operation is unsupported unless a provider explicitly overrides it — this means a new provider gets correct capability-blocking behavior for free just by NOT implementing methods it can't support, rather than needing to duplicate logic already captured incapabilities.rs.service.rsis what actually enforces layer 1 against layer 2:VfsServicechecks the capability before calling the provider method, and translates the outcome into aVfsOutcomecarrying a user-facinghintstring. Any code path that touches a file must go throughVfsService, not directly through aFsProviderimplementation — if you find yourself callingprovider.chmod()directly from anywhere outsideservice.rs, that's a bug: the capability check gets bypassed.
The VfsOutcome contract
Ok(T)— succeeded cleanly, no caveats.Blocked { operation, reason, hint }— not attempted; capability check failed.hintshould beSome(...)for anything a user could plausibly fix (move to internal storage, re-grant permission) andNoneonly for genuine hard failures.Degraded { value, caveat }— attempted AND succeeded, but with a caveat worth surfacing (e.g. non-atomic rename on SAF). Never collapse this intoBlocked— the operation worked; lying about that would be worse than not warning at all.
When adding a new operation to VfsService, decide up front which of
these three outcomes each supported filesystem type produces, and write a
test for each case — see vfs/service.rs's test module for the pattern
(one test per outcome type, per relevant provider).
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.
- 9d ago First seen · 70 lines · 0 tokens per session scan A 1f70b9905859
40-vfs-saf-architecture is a cursor rule published in the GitHub repository MannanSaood/termi (8 stars, last pushed 9d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 812 tokens. 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 2026-08-31.
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