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The single most common point of confusion when first encountering Trust Posture: “is it a kind of card?” or “does it compose into the agent’s card?” No. Postures and cards are parallel artifact types. They share infrastructure (the composer idiom, KV caching, the audit log, strictest-wins rules) but their data planes are independent. A posture never folds into a card; a card never folds into a posture. This page makes the distinction explicit, and shows where the two surfaces do cooperate — at well-defined join points downstream of either artifact’s cascade.

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The two cascades

Cards have an agent leaf because cards encode per-agent runtime treatment (“what is this agent allowed to do?”). Postures have no agent leaf because postures are inherently fleet-level — they observe a group of agents and decide whether the group’s collective behavior warrants alarm.

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The axes are orthogonal

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Concrete examples

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Where they cooperate (two join points)

Postures and cards intersect at exactly two well-defined join points downstream of either cascade.

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1. Detector input

The sideband detectors read two sources at sweep time:
  • The team’s effective Posture (policy) — tells the detector when to fire.
  • The team members’ canonical Alignment Cards (data) — provides what to look at.
The posture’s body specifies thresholds (e.g., pairwise_governance_floor_below: 0.5); the card’s content (declared values, conscience, integrity sections) is the substrate the detector analyzes.

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2. Carryover bridge

Posture-driven findings write rows to pending_advisories tagged with source: sideband.{coherence,fault_line,fleet}. The gateway, on the next turn for any affected agent, reads those rows alongside the agent’s canonical cards and lets card-driven enforcement decide the runtime treatment. The slogan: posture detects; cards treat.

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Why no overlap is intentional

If a posture could set per-agent forbidden_tools, you’d have two answers to “is rm -rf blocked?” — the card’s and the posture’s — and the composer would need to merge them. That’s a design smell. The line we hold:
  • Per-agent identity, per-agent treatment lives on cards.
  • Fleet hygiene lives on postures.
  • Mode vocabulary (off | observe | nudge | enforce) and strictest-wins composition are shared idioms, applied within each cascade independently.
The result: extending the posture body to add Trust-Rating gating, attestation flags, control-tags, or new sideband sources doesn’t touch the card schemas. Extending cards (new principal types, new exemption granularity) doesn’t touch postures. Each artifact stays small enough to reason about.

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See also