git:20260919.d2affb4 to git:20260923.47f11bb

---

title: Agent Harness design contract

created: 2026-09-19

updated: 2026-09-19

colors:

status: semantic-names-not-fixed-terminal-colors

typography:

prose: system-sans

code: system-monospace

rounded: none-required

spacing: compact-readable

components:

- status-line

- command-block

- evidence-callout

sources:

- ../../prds/prd-agent-harness-2026-09-19/prd.md

---

# Brand and style

Agent Harness is direct, inspectable and calm. Documentation leads with what a developer can do,

then states current limits without promotional inflation. The product has no required graphical

surface for v1; this contract governs documentation, terminal examples and future explanatory UI.

# Colors

Status meaning must not depend on color. Any future surface uses named semantic states—supported,

preview, planned, unsupported, unknown and failed—and renders their text labels visibly.

# Typography

Use the host system's readable sans-serif for prose and monospace for commands, paths and structured

output. Avoid decorative display typography in operational surfaces.

# Layout and spacing

Put the outcome and next safe action first. Keep commands copyable and keep caveats adjacent to the

claim they limit. Dense evidence belongs behind a link, not above the first experiment.

# Components

- **Status line:** literal state plus subject and evidence scope.

- **Command block:** complete executable command with no hidden prerequisite.

- **Evidence callout:** observed behavior, exact surface and limitations.

# Dos and don'ts

Do distinguish generated configuration, implemented policy and observed native behavior. Do not use

visual polish to imply qualification, savings or capability that has not been measured.