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/seven128/project-tiny-context-harness/context_surface_contractnpx skills add Seven128/project-tiny-context-harness --skill context_surface_contractgit clone --depth 1 https://github.com/Seven128/project-tiny-context-harnessWhat 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 | $0.00126 | $0.02639 |
| Opus 5 | $0.00063 | $0.01319 |
| Sonnet 5 | $0.00025 | $0.00528 |
| Haiku 4.5 | $0.00013 | $0.00264 |
Grade A, and why
context_surface_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.
How it starts
The opening of the file, as written. The whole thing — 206 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Context Surface Contract
Package-Managed Boundary
This Skill is generated by ty-context sync and owned by the Harness package. Do not edit the generated context_surface_contract Skill directly.
Project-specific Product Surface responsibilities belong in project_context/** and an optional <harnessRoot>/skills/surface_contract/SKILL.md. This is the sole package-managed owner for durable surface responsibility; it must not contain business-specific page duties, provider facts, project names, raw payload schemas or product examples.
Purpose
Help agents turn broad product/UI principles into concrete, project-owned Product Surface Contracts while keeping Minimal Context small.
This Skill owns where user-facing information, actions and feedback belong, including main/drilldown/diagnostic/detail responsibility and cross-surface ownership. context_product_plan owns goals, users, business rules, flows and acceptance meaning; context_uiux_design owns Design Authority/tokens/rationale/adopted-target interpretation; design-resource-authoring owns resource generation. This Skill owns none of those, performs no implementation acceptance and creates no Gate.
A Product Surface is any user-facing interface where users make judgments, take actions and receive feedback. Covered platforms include Web apps, dashboards, admin or operations UI, mobile screens, desktop windows, game UI/HUD/menu scenes, CLI/TUI output, browser extension or plugin UI, and embedded, kiosk or device UI.
Use two depths without creating new roles: Product Surface Contract for cross-surface/main-versus-drilldown ownership, and an optional on-demand Screen Contract when one screen needs stable entry/exit/shared-state, information hierarchy, layout regions, navigation, variants or material-control semantics. Start from managed product-surface-contract.md or screen-contract.md; do not require both for every task.
Context Roles
Do not add a new context_role.
Use existing roles:
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 · 206 lines · 126 tokens per session scan A b159b7c4674f
context_surface_contract is a skill published in the GitHub repository Seven128/project-tiny-context-harness (3 stars, last pushed 3d ago), licensed MIT. It adds 126 tokens to every session and 2,639 once invoked, about $0.0006 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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