The C8-C16 harness layer (opencode plugin, MCP server, marker, fw_* protocol,
attribution) was undocumented in docs/ — a user could run the substrate but
not discover or set up the harness wiring.

- docs/HARNESS.md: the marker (sole activation source), wiring a project, the
  fw_* tools (plugin + MCP + CLI-verb mapping), the protocol, harness + model
  attribution, session/ledger state + legibility/recovery, plugin install
  (global + repo-local), codex/claude MCP wiring, and the two E2E proofs.
- demo/wire_board.sh: one-step, non-destructive wiring of a real project (bare
  board HEAD->main + mirror HEAD + SCRATCH-BOARDS smoke test + gitignored marker).
- README Layout + a new 'Harness auto-use' section; QUICKSTART + 00-ORIENTATION
  (pieces table, which-job, glossary); docs/README index; CHANGELOG (Unreleased).
- demo/external_work_e2e.sh is now named alongside owner_test.sh in the docs.

No code change: suite unchanged (177 python + 28 bun green).