ADR-0174 - Fixed native instruction targets

Context

ADR-0173 allowed setup to follow an existing Codex override. That makes installation depend on incidental user scaffolding and lets setup occupy a file whose purpose is exceptional precedence. The ordinary global instruction files are the stable integration surface [CODEXGLOBAL] [CLAUDEDIR] [OPENCODERULES].

Decision

1. Use the ordinary native file. Each explicit harness identifier maps to its documented normal global instruction file. Existing content is preserved around the neutral owned block.
2. Never chase precedence. Setup does not redirect installation into overrides, alternate instruction files, or discovered scaffolding.
3. Report shadowing. When another configuration would prevent the normal file from loading, setup stops. The user resolves that harness configuration outside Suspec.

Narrowed decisions

• ADR-0173: native inline installation survives; targeting a non-empty Codex override retires.
• ADR-0172: fixed documented targets and fail-closed precedence survive unchanged.

Consequences

• Setup behaves the same on clean and customized machines.
• Exceptional harness configuration remains owned by the user.

Status

Accepted (2026-08-09). Narrows ADR-0172 and ADR-0173.