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 agents/burin-labs/harn/cache_contractgit clone --depth 1 https://github.com/burin-labs/harnWhat 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 | $0.00281 |
| Opus 5 | $0.00000 | $0.00140 |
| Sonnet 5 | $0.00000 | $0.00056 |
| Haiku 4.5 | $0.00000 | $0.00028 |
Grade A, and why
cache_contract 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
Workspace Anchor Cache Contract
The session workspace_anchor is transient turn context, not durable system
prompt content.
The contract is:
SessionState::system_promptmust stay free of{{workspace_*}}and{{project_*}}template tokens.- active workspace state is rendered through the canonical
workspace_anchorreminder provider instead - downstream callers that still assemble
pipeline_inputor system prompt text by hand must keep workspace/project fields out of the persisted session prompt surface
The canonical reminder body is:
<workspace-anchor>
primary: /Users/me/projects/X
additional_roots:
- /Users/me/projects/Y (mount_mode: read_only, mounted_at: 2026-05-23T10:15:00Z)
</workspace-anchor>
That reminder is injected on SessionStart and refreshed after each turn via
the OnBudgetThreshold provider pass. Re-anchoring therefore updates the next
turn's reminder payload without rewriting the stored session prompt.
In debug builds, Harn asserts this contract when it records a session system
prompt. If the prompt text contains {{workspace_*}} or {{project_*}}, the
runtime panics with HARN-CACHE-001 so the offending caller can move that data
into reminder space instead.
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 · 34 lines · 0 tokens per session scan A c76b8f2fa6cd
cache_contract is an agent published in the GitHub repository burin-labs/harn (20 stars, last pushed 2d ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 281 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 2026-08-30.
Other agents, from other repositories
RULES
Agent "RULES" from phel-lang/phel-lang, covering phel rules + cli, rules, new features (v0.30 – main), gotchas and cli.
fixture-reviewer
Audits .test integration fixtures under tests/php/Integration/Fixtures for drift against the current compiler output. Use after lexer, parser, analyzer, or emitter changes.
module-docs-sync
Audits and updates CLAUDE.md files in src/php/ modules to match the actual code. Use after large refactors, new modules, or periodic maintenance.
tdd-coach
Guides test-driven development with red-green-refactor discipline. Use when implementing features or fixes with TDD.
quick-syntax
One-screen cheatsheet. For exhaustive rules see RULES.md; for typing details see tasks/typed-defn.md.
index
Agent "index" from phel-lang/phel-lang, covering agent index, intent map and examples.