Migrated from Method backlog

This issue was created from a legacy filesystem backlog card. GitHub Issues are now the live work tracker; repository docs remain Method evidence.

Source backlog: docs/method/backlog/v0.1.0/KERNEL_contract-reading-identity-and-bounded-payloads.md
Original lane: v0.1.0
Original legend: KERNEL

Original backlog card

Contract Reading Identity And Bounded Payloads

Status: implemented local boundary.

Depends on:

• Contract QueryView observer bridge
• Contract-aware receipts and readings
• 0018 - Contract-Hosted File History Substrate

Why now

Contract observations need honest identities and bounded payload behavior before
large-file consumers can trust them.

What it should look like

Reading identity should include:

• observed coordinate;
• contract family, artifact, and schema identity;
• query op id;
• vars digest;
• observer/read law version where available;
• aperture or budget request;
• witness refs;
• budget, rights, residual, plurality, conflict, or obstruction posture.

Acceptance criteria

• Same query, same basis, same vars, and same observer law produce the same
  reading identity.
• Schema, op id, vars, basis, or aperture changes produce different identity.
• A bounded text-window fixture returns only the requested aperture.
• Payload size is bounded by the request or posture reports budget limitation.
• Unsupported or stale basis returns obstruction.

Non-goals

• Do not canonicalize text-editor state in Echo core.
• Do not require full payload materialization before identity can be computed.
• Do not use CAS content hash alone as reading identity.