docs: finalize XZBT-NGN project records

.labyricorn/project/contents.lr

@@ -2,26 +2,71 @@ _model: project
 ---
 schema_version: 1
 ---
-project_id: labyricorn-project-template
+project_id: xzbt-ngn
 ---
-title: Labyricorn Project Template
+title: XZBT-NGN Exhibit Engine
 ---
 summary:
 
-Initial template and publishing structure for Labyricorn-compatible projects and development logs.
+A generic single-exhibit host for XZBT Exhibit Contract 5.3: session negotiation, descriptor-driven control discovery, presentation-surface rendering, state inspection, and set/invoke operations, with no exhibit-specific vocabulary in the host.
 ---
 status: active
 ---
-started: 2026-08-23
+started: 2026-09-13
 ---
-author: Labyricorn
+author: cgcha
 ---
-repository_url: https://git.labyricorn.com/Labyricorn/labyricorn-project-template
+repository_url: https://git.labyricorn.com/Labyricorn/XZBT-NGN
 ---
 default_branch: main
 ---
-tags: template, lektor, python
+tags: xzbt, xzbt-ngn, exhibit-engine, contract-5-3, multi-surface, javascript
 ---
-body:
+body: |
+  XZBT-NGN is the host, orchestration and integration environment for exhibits that
+  speak the XZBT Exhibit Contract. It does not replace an exhibit; it extends one.
+  Everything an exhibit offers is discovered through the contract's target surface
+  and rendered generically, so no exhibit-specific vocabulary is hard-coded
+  anywhere in the host.
 
-Starter template providing the standard .labyricorn/ publishing records, assistant instructions, devlog structure, and repository tooling for publication on Labyricorn.
+  ## Completed work
+
+  The contract-boundary MVP is implemented and verified. A single unmodified host
+  negotiates a session, requests `describe`, renders discovered capabilities and
+  targets grouped by the exhibit's own categories, reads authoritative state,
+  submits set and invoke operations with full descriptor validation, displays
+  events with source and sequence, tracks registry and state revisions, and
+  recovers from synchronization loss. That same unmodified host drives five
+  maintained reference exhibits -- Aquarium, Planetarium, Haunted House, Museum
+  Gallery and SciFi-XZBT -- with no fixture-specific logic.
+
+  Contract 5.3 multi-surface support is complete. The host discovers presentation
+  surfaces from `describe`, resolves their URLs against the supplying exhibit's
+  document URL inside a same-origin boundary, and renders each in a local pane
+  that carries no contract session of its own. Museum Gallery exercises three
+  surfaces; SciFi-XZBT declares a console surface plus an Observation surface that
+  attaches to the console's single authority and never creates a second one.
+
+  Verification is automated and repeatable: 154 tests pass under `node --test`
+  with no npm dependencies and no build step, and the loopback server exposes only
+  `public/`, `src/` and `test-fixtures/` while denying paths that escape them.
+
+  ## Formal design work
+
+  This repository is the canonical home of the XZBT Exhibit Contract Specification
+  (5.3 current; 5.2 retained as its historical predecessor, additively superseded),
+  the XZBT Exhibit Authoring Guide, and the NGN Implementation Plan. The
+  multi-surface architectural model was specified in full before implementation
+  and fixes the Step 6 / Step 7 boundary at the schema level: a surface descriptor
+  may name a document the host can load, and may never name a display transport,
+  casting protocol, network endpoint or device class.
+
+  ## Future work
+
+  Step 7 -- display endpoints, meaning where a surface is physically shown -- is
+  specified by contrast in the multi-surface model but is not started. Casting and
+  remote displays, MIDI, MCP, webhooks, scenario authoring, recording, telemetry
+  connectors, integration adapters, packaging, multi-exhibit orchestration and
+  persistence all remain unimplemented; the host keeps in-memory state only. Five
+  non-blocking follow-up items requiring sustained human observation remain open
+  from the Step 6 closure.