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 skills/nrdxp/predicate/boundarynpx skills add nrdxp/predicate --skill boundarygit clone --depth 1 https://github.com/nrdxp/predicateWhat 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 | $0.00104 | $0.04486 |
| Opus 5 | $0.00052 | $0.02243 |
| Sonnet 5 | $0.00021 | $0.00897 |
| Haiku 4.5 | $0.00010 | $0.00449 |
Grade A, and why
boundary 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.
How it starts
The opening of the file, as written. The whole thing — 394 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Boundary Protocol v1.0: IBC Sufficiency & Refinement
This skill defines what every Initial Boundary Condition (IBC) MUST possess before an expensive walk is launched from it, and the cheap-tier refinement loop that manufactures such boundaries.
The key words "MUST", "MUST NOT", "SHOULD", and "MAY" are to be interpreted as described in BCP 14 (RFC 2119, RFC 8174).
Philosophy: Optimize for Cheap Rejection
A good IBC is not one that maximizes the probability the walk succeeds. It is one that makes the failure modes cheap and early. A wrong frame can never be fully prevented at authoring time; what can be guaranteed is that the walk detects and rejects it in its first few hundred tokens instead of its last fifty thousand.
This follows from the cost asymmetry of cascade control: iterating in boundary-space (cheap models + human revising a prompt document) costs orders of magnitude less than iterating in trajectory-space (re-running an architect-class walk). Error-correction iterations therefore belong in the cheap outer loop. The expensive walk should launch from a fixed point $\text{IBC}^*$ of the cheap refinement mapping and run as close to one-shot as the task allows.
The most expensive failure mode of a high-capability walker is a confidently-wrong frame: long-horizon coherence builds a large, internally consistent structure on a false premise without the local error signals that would trip a weaker model into visible incoherence. Premise verification before the expensive call has the highest leverage-per-token of any activity in the system.
Trust as an Anti-Goodhart Mechanism
A micro-specified boundary induces a compliance posture: the walk optimizes for letter-satisfaction of the rubric and produces rubric-satisfying, goal-missing output. A boundary that grants explicit discretion over its delegated questions ("these calls are yours; log your reasoning") shifts the optimization target from satisfy the spec to achieve the goal under constraints. The partnership dyad is structural, not sentimental:
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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 · 394 lines · 104 tokens per session scan A e4a210788ee9
boundary is a skill published in the GitHub repository nrdxp/predicate (10 stars, last pushed 8d ago), licensed MIT. It adds 104 tokens to every session and 4,486 once invoked, about $0.0005 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 2026-08-31.
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