Steps 6.4-6.7B — Local surfaces, reference-exhibit validation, SciFi Observation surface

One commit for the work accumulated in the working tree since Step 6.3, which had never been split into per-step commits: - src/local-surfaces.js + src/surface-url.js (new); src/ui.js, src/validation.js, src/connection.js and public/index.html updated for local-surface hosting and generic surface rendering - tests: local-surfaces (20), scifi-surfaces (24) and postmessage-interop (7) new; connection/museum-gallery/surface-validation suites updated - reference exhibits: shared/contract-core.js defaults to Contract 5.3 (major 5, minor 3, xzbt 5.3); museum-gallery advertises its surface catalog; aquarium/haunted-house/planetarium adapters updated - SciFi-XZBT (Step 6.7A/6.7B): surface-mode.js + surface-bus.js, Observation-surface boot branch, local-change hooks, view.pillars / view.warp-flight targets; fixture byte-identical to G:/.vibe/SciFi-XZBT - SciFi-XZBT contract adapter handshake fix: the inbound bridge filter no longer gates on an exact advisory xzbt value (Contract 5.3 §6.5), only on its presence/type, matching the host's own envelope validation; the adapter now advertises contract minor 3 / version 5.3.0, which it already implemented via the 5.3 surfaces field. Root cause of the five failing postmessage-interop tests (host hello was silently dropped). - docs: architecture 6.4 and 6.7A, reference 6.6 and 6.7; evidence logs; test-fixtures/PROVENANCE.md resync record Test results: NGN 154/154 (was 149/154); postmessage-interop 7/7 (was 2/7); SciFi contract harness 21/21, real-adapter suite 32/32. git diff --check clean for changed files; two pre-existing trailing-whitespace lines remain in test-fixtures/reference-exhibits/scifi/index.html, copied verbatim from the authoritative SciFi source. Step 6.7 live verification (browser Observation, packaged standalone) is still pending and is not claimed here.
2026-09-14 19:45:27 -07:00
parent ed76cf6189
commit 745912e451
40 changed files with 5346 additions and 210 deletions
@@ -29,3 +29,76 @@ Local compatibility corrections:
 NGN has no fixture-specific target logic. These corrections apply only to
 the local fixture copies. No upstream fixes or independent conformance
 certification are claimed.
+
+## Step 6.7B resync (2026-09-15)
+
+The `scifi/` fixture was resynced from the real SciFi-XZBT exhibit source at
+`G:/.vibe/SciFi-XZBT/` after that repo's Step 6.7B implementation (SciFi
+Observation Surface Integration, `docs/architecture/XZBT-NGN-Step6.7A-SciFi-Observation-Surface.md`).
+
+Copied files (byte-for-byte from source, no fixture-local corrections):
+
+- `index.html` — two new `<script>` tags for `surface-mode.js`/`surface-bus.js`
+- `js/app.js` — boot-mode resolution, console/observation branching, the
+  surface-attachment bus wiring, `view.pillars`/`view.warp-flight` routing
+- `js/contract-adapter.js` — `surfaces`/`instanceId` constructor options,
+  the `view.pillars`/`view.warp-flight` targets, `onLocalChange`/`onLocalAction`
+  hooks, `describe()`'s conditional `surfaces` field, version bump to 5.3.0
+- `js/observation-engine.js` — WARP/PILLARS dock buttons now route through
+  `onMutation` (matching the existing VIEWPORT/RED ALERT/PRESET pattern)
+  instead of mutating engine state directly
+- `css/style.css` — additive `body.surface-observation` rules
+- `js/surface-mode.js` (new) — boot-mode resolver + surface catalog
+- `js/surface-bus.js` (new) — instance-scoped BroadcastChannel sync
+
+No fixture-local corrections were added on top of this resync; the fixture
+is a faithful mechanical copy of the source as it stood after Step 6.7B.
+`js/audio.js`, `js/config.js`, `js/core-animations.js`, `js/visualizer.js`,
+`js/observation-bezels.js`, `js/generative-experience.js`, and `js/control-bus.js`
+were not touched by Step 6.7B and were not recopied. `dist/` was not
+regenerated (no PowerShell available in the environment that performed this
+resync); it still reflects a pre-6.7B build and should be rebuilt from
+source before any test or procedure that opens the packaged file.
+
+## SciFi adapter handshake correction (2026-09-15)
+
+Correction to the record above: the Step 6.7B resync note listed a "version
+bump to 5.3.0" for `js/contract-adapter.js`, but no such bump was present in
+the file as resynced — it still read `version = '5.2.0'` / `contractMinor = 2`.
+The adapter also still carried a pre-5.3 inbound gate in `_setupWindowBridge`:
+
+```js
+if (!e.data || typeof e.data !== 'object' || e.data.xzbt !== '5.2') return;
+```
+
+That is an exact-string comparison against the advisory `xzbt` field, which
+Contract 5.3 §6.5 designates as diagnostics-only metadata ("The negotiated
+session contract major/minor is authoritative after handshake"). Because
+XZBT-NGN's host stamps outgoing envelopes `xzbt: '5.3'` (Step 6.3), the gate
+silently dropped every host message — including `hello` — and NGN's handshake
+timed out against this exhibit (`tests/postmessage-interop.test.js`, four
+tests).
+
+Two source-side corrections were made in `G:/.vibe/SciFi-XZBT/js/contract-adapter.js`
+and then copied here verbatim, keeping the one-directional source -> fixture
+flow this file documents:
+
+1. The inbound filter now checks the advisory field's *presence and type*
+   (`typeof e.data.xzbt !== 'string'`), matching how XZBT-NGN's host validates
+   the same field. It no longer branches on any particular value, so the
+   field cannot act as a compatibility gate for any sender.
+2. The adapter advertises the contract it actually implements: `contractMinor`
+   `2` -> `3` and the exhibit product version `'5.2.0'` -> `'5.3.0'` (its
+   `describe()` already emitted the Contract 5.3 `surfaces` field added by
+   Step 6.7B). The file header now reads "Specification v5.3" to match.
+
+The outbound advisory `xzbt: '5.2'` stamps on this adapter's own envelopes were
+deliberately left unchanged: §6.5 makes the value non-authoritative, Step 6.7B
+documented the envelope as unchanged, and no receiver — NGN included — reads
+that value for admission. `dist/` remains a stale generated artifact and was
+not regenerated.
+
+Resynced file (source and fixture byte-identical,
+SHA-256 `10ED30527153D5B30F23557BA6EC427884D470AB6561AC33C47E7F17AFA28DD9`):
+
+- `js/contract-adapter.js`
@@ -0,0 +1,172 @@
+- banner:
+  - heading "XZBT-NGN Exhibit Engine" [level=1]
+  - paragraph: Contract 5.2/5.3 · One exhibit at a time
+- main:
+  - heading "Connection" [level=2]
+  - generic: Exhibit URL (same origin)
+  - textbox "Exhibit URL (same origin)":
+    - /placeholder: /public/exhibits/example/index.html
+    - text: http://127.0.0.1:4173/test-fixtures/reference-exhibits/museum-gallery/control.html
+  - button "Load exhibit"
+  - button "Reconnect"
+  - button "Disconnect"
+  - paragraph: Enter a trusted exhibit's local served path or a URL on this origin. Load exhibit also switches exhibits. Reconnect starts a new session, or reloads the last exhibit after disconnect.
+  - status: connected · synchronized
+  - paragraph: Museum Gallery · 0.1.0 · Contract 5.3
+  - paragraph: "Exhibit location: http://127.0.0.1:4173/test-fixtures/reference-exhibits/museum-gallery/control.html"
+  - iframe:
+    - banner:
+      - heading "Museum Gallery — Control Room" [level=1]
+      - generic: Primary surface · Contract 5.3 · standalone-capable
+      - generic: host attached
+    - main:
+      - paragraph: The Orrery
+      - paragraph: "Lighting: 60%"
+      - paragraph: "Rotation: 0.4x"
+      - paragraph: "Labels: ON"
+      - paragraph: "Attached non-primary surfaces: 0"
+    - complementary:
+      - heading "Artifact" [level=2]
+      - generic: Selected artifact
+      - combobox "Selected artifact":
+        - option "The Orrery" [selected]
+        - option "Star Map"
+        - option "Meteorite Fragment"
+      - heading "Environment" [level=2]
+      - generic: Lighting level
+      - generic: 60%
+      - slider "Lighting level 60%"
+      - generic: Rotation speed
+      - generic: 0.4x
+      - slider "Rotation speed 0.4x"
+      - generic: Labels enabled
+      - button "Toggle" [pressed]
+      - heading "Actions" [level=2]
+      - button "Flash spotlight"
+    - contentinfo:
+      - generic: Control Room
+      - generic: Control Room standing by.
+  - heading "Exhibit controls (5)" [level=2]
+  - generic "Capabilities"
+  - paragraph: Reported values are authoritative. New values are drafts; select Set or Invoke to submit. Rediscovery resets drafts.
+  - heading "gallery" [level=3]
+  - article:
+    - heading "Selected Artifact" [level=3]
+    - code: artifact.selected
+    - paragraph: selection · readable · writable
+    - status: "Reported value: \"the-orrery\""
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - combobox "New value":
+      - option "The Orrery" [selected]
+      - option "Star Map"
+      - option "Meteorite Fragment"
+    - button "Set"
+  - article:
+    - heading "Lighting Level" [level=3]
+    - code: lighting.level
+    - paragraph: range · readable · writable
+    - status: "Reported value: 0.6"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "0.6"
+    - button "Set"
+  - article:
+    - heading "Rotation Speed" [level=3]
+    - code: rotation.speed
+    - paragraph: range · readable · writable
+    - status: "Reported value: 0.4"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "0.4"
+    - button "Set"
+  - article:
+    - heading "Labels Enabled" [level=3]
+    - code: labels.enabled
+    - paragraph: state · readable · writable
+    - status: "Reported value: true"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - checkbox "New value" [checked]
+    - button "Set"
+  - heading "action" [level=3]
+  - article:
+    - heading "Spotlight Flash" [level=3]
+    - code: action.spotlight-flash
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - heading "Presentation surfaces (3)" [level=2]
+  - paragraph: Open Contract 5.3 presentation surfaces locally below. URLs resolve against the supplying exhibit. Disconnecting or switching exhibits closes these views. Remote/cast displays remain deferred.
+  - article:
+    - heading "Control Room" [level=3]
+    - code: surface.control
+    - generic: Primary
+    - generic: "Role: control"
+    - paragraph: "URL: control.html"
+    - status: Open in the authoritative control frame. Use Connection controls to reload or disconnect.
+    - button "Open" [disabled]
+    - button "Reload" [disabled]
+    - button "Close" [disabled]
+  - article:
+    - heading "Artifact Display" [level=3]
+    - code: surface.artifact
+    - generic: Non-primary
+    - generic: "Role: ambient"
+    - paragraph: "URL: artifact.html"
+    - status: open
+    - button "Open" [disabled]
+    - button "Reload"
+    - button "Close"
+    - iframe:
+      - banner:
+        - heading "Museum Gallery — Artifact Display" [level=1]
+        - generic: Non-primary surface · attaches to the Control Room
+        - generic: surface
+      - main:
+        - paragraph: The Orrery
+        - paragraph: "Lighting: 60%"
+        - paragraph: "Rotation: 0.4x"
+        - paragraph:
+          - button "Cycle artifact"
+        - paragraph: Attached to Control Room.
+      - contentinfo:
+        - generic: Artifact Display
+        - generic: Waiting for shared state.
+  - article:
+    - heading "Information Wall" [level=3]
+    - code: surface.info-wall
+    - generic: Non-primary
+    - generic: "Role: information"
+    - paragraph: "URL: info-wall.html"
+    - status: open
+    - button "Open" [disabled]
+    - button "Reload"
+    - button "Close"
+    - iframe:
+      - banner:
+        - heading "Museum Gallery — Information Wall" [level=1]
+        - generic: Non-primary surface · attaches to the Control Room
+        - generic: surface
+      - main:
+        - paragraph: The Orrery
+        - paragraph: "Labels: ON"
+        - paragraph:
+          - button "Toggle labels"
+        - paragraph: Attached to Control Room.
+      - contentinfo:
+        - generic: Information Wall
+        - generic: Waiting for shared state.
+  - heading "State and metadata" [level=2]
+  - button "Refresh state"
+  - generic "Session and exhibit metadata"
+  - generic "Current persistent state"
+  - heading "Protocol diagnostics" [level=2]
+  - generic "Incoming events"
+  - generic "Protocol and errors"
@@ -0,0 +1,846 @@
+- banner:
+  - heading "XZBT-NGN Exhibit Engine" [level=1]
+  - paragraph: Contract 5.2/5.3 · One exhibit at a time
+- main:
+  - heading "Connection" [level=2]
+  - generic: Exhibit URL (same origin)
+  - textbox "Exhibit URL (same origin)":
+    - /placeholder: /public/exhibits/example/index.html
+    - text: /test-fixtures/reference-exhibits/scifi/index.html
+  - button "Load exhibit" [active]
+  - button "Reconnect"
+  - button "Disconnect"
+  - paragraph: Enter a trusted exhibit's local served path or a URL on this origin. Load exhibit also switches exhibits. Reconnect starts a new session, or reloads the last exhibit after disconnect.
+  - status: connected · synchronized
+  - paragraph: SciFi-XZBT · 5.2.0 · Contract 5.3
+  - paragraph: "Exhibit location: http://127.0.0.1:4173/test-fixtures/reference-exhibits/scifi/index.html"
+  - iframe:
+    - banner:
+      - generic "Click to Change Sci-Fi Universe":
+        - generic: STARFLIGHT
+        - generic: ▼
+      - generic: "INTERPRISE-G: MAIN BRIDGE"
+      - button "MUTE"
+      - generic: 75%
+      - generic: STARFLIGHT SOUND MATRIX v2.9
+    - main:
+      - complementary:
+        - generic: STARSHIP PRESETS
+        - 'button "Interprise-G: Main Bridge STARFLIGHT COMMAND"':
+          - generic: "Interprise-G: Main Bridge"
+          - generic: STARFLIGHT COMMAND
+        - 'button "Interprise-G: Main Engineering STARFLIGHT COMMAND"':
+          - generic: "Interprise-G: Main Engineering"
+          - generic: STARFLIGHT COMMAND
+        - 'button "Interprise-G: Crew Quarters STARFLIGHT COMMAND"':
+          - generic: "Interprise-G: Crew Quarters"
+          - generic: STARFLIGHT COMMAND
+        - 'button "USS Wayfarer: Bridge STARFLIGHT COMMAND"':
+          - generic: "USS Wayfarer: Bridge"
+          - generic: STARFLIGHT COMMAND
+        - 'button "USS Wayfarer: Class-N Worp Core STARFLIGHT COMMAND"':
+          - generic: "USS Wayfarer: Class-N Worp Core"
+          - generic: STARFLIGHT COMMAND
+        - 'button "USS Defiance: Tactical Bridge STARFLIGHT COMMAND"':
+          - generic: "USS Defiance: Tactical Bridge"
+          - generic: STARFLIGHT COMMAND
+        - 'button "Deep Space 8: Ops Center STARFLIGHT COMMAND"':
+          - generic: "Deep Space 8: Ops Center"
+          - generic: STARFLIGHT COMMAND
+        - 'button "Interprise NCC-1701.5: Bridge (TOS) STARFLIGHT COMMAND"':
+          - generic: "Interprise NCC-1701.5: Bridge (TOS)"
+          - generic: STARFLIGHT COMMAND
+        - 'button "Interprise NCC-1701.5: Engineering (TOS) STARFLIGHT COMMAND"':
+          - generic: "Interprise NCC-1701.5: Engineering (TOS)"
+          - generic: STARFLIGHT COMMAND
+        - 'button "Interprise NS-01: Command Bridge STARFLIGHT COMMAND"':
+          - generic: "Interprise NS-01: Command Bridge"
+          - generic: STARFLIGHT COMMAND
+      - generic: "INTERPRISE-G: MAIN BRIDGE"
+      - generic: Warm, low-frequency 50Hz hull tone with gentle ventilation and soft LCARD computer chirps.
+      - generic: AUDIO ENGINE
+      - generic: STANDBY
+      - generic: CORE FREQ
+      - generic: 58.0 Hz
+      - button "▶ ENGAGE":
+        - generic: ▶
+        - generic: ENGAGE
+      - button "WARP JUMP"
+      - button "RED ALERT"
+      - button "YELLOW ALERT"
+      - button "WATCH EXPERIENCE"
+      - generic: Full-screen procedural visuals, soundscape, telemetry, events, and optional local AI announcements.
+      - 'generic "Toggle starship viewport window frame (ON: framed starship lounge / OFF: pure deep space)"':
+        - generic: VIEWPORT
+        - checkbox "Toggle Observation Viewport Frame" [checked]
+        - generic: "ON"
+      - 'generic "Toggle vertical structural window pillars / mullions (OFF: unobstructed panoramic view / ON: structural posts)"':
+        - generic: PILLARS
+        - checkbox "Toggle Window Pillars"
+        - generic: "OFF"
+      - generic "Controls how frequently and intensely Observation generates transient visual activity":
+        - generic: ACTIVITY
+        - slider "Observation activity level"
+        - generic: 60%
+      - generic "Keep OBSERVATION profile/status information visible. Turn off to fade it out over 30 seconds.":
+        - generic: HUD HOLD
+        - checkbox "Keep Observation information visible" [checked]
+        - generic: "ON"
+      - generic: MAIN MASTER VOLUME
+      - generic: 75%
+      - generic: "-2.5 dB"
+      - button "MUTE"
+      - button "25%"
+      - button "50%"
+      - button "75%"
+      - button "MAX"
+      - button "−"
+      - slider "Main Volume"
+      - button "+"
+      - generic: FNC // FUTURISTIC NOICE CANCELLATION
+      - generic: ACTIVE
+      - button "FNC ENABLED" [pressed]
+      - generic: FNC LEVEL
+      - slider "Futuristic Noice Cancellation level"
+      - generic: 65%
+      - generic: "FNC comfort filter remains applied. Adaptive watchdog memory reset: preset change."
+      - generic: ACOUSTIC FREQUENCY SPECTRUM
+      - generic: PROCEDURAL HARMONIC ANALYSIS
+      - generic: "SPECTRUM BIN: 32 CH // REAL-TIME FFT"
+      - generic: PROCEDURAL SOUND ENGINE MIXER
+      - generic: LIVE PARAMETER MODULATION
+      - generic: 1. HULL DRONE
+      - generic: 65%
+      - generic: LEVEL
+      - slider
+      - generic: BASE TONE
+      - generic: 50 Hz
+      - slider
+      - generic: DAMPING CUTOFF
+      - generic: 105 Hz
+      - slider
+      - generic: 2. WORP CORE
+      - generic: 35%
+      - generic: LEVEL
+      - slider
+      - generic: PULSE RATE (BPM)
+      - generic: 48 BPM
+      - slider
+      - generic: REACTOR PITCH
+      - generic: 58 Hz
+      - slider
+      - generic: 3. LIFE SUPPORT
+      - generic: 55%
+      - generic: LEVEL
+      - slider
+      - generic: AIRFLOW AIR FILTER
+      - generic: 1600 Hz
+      - slider
+      - generic: 4. TELEMETRY
+      - generic: 45%
+      - generic: LEVEL
+      - slider
+      - generic: BACKGROUND CHIRP DENSITY
+      - generic: 65%
+      - slider
+      - complementary:
+        - generic: INTERMIX CASCADE
+        - generic: INTERMIX CHAMBER // ACTIVE
+        - generic: GENERATIVE EXPERIENCE
+        - generic: LOCAL WEBLLM + KOKORO TTS
+        - generic: LOCAL GENERATIVE SYSTEM
+        - generic: STANDBY
+        - text: LANGUAGE MODEL
+        - text: Qwen3-1.7B-q4f16_1-MLC
+        - text: Automatically prepared when the experience starts. No model selection required.
+        - text: WEBLLM
+        - generic: "OFF"
+        - text: KOKORO
+        - generic: "OFF"
+        - button "PREPARE AI"
+        - button "GENERATE NOW" [disabled]
+        - checkbox "AUTO UPDATES" [checked]
+        - text: AUTO UPDATES
+        - checkbox "SPEAK" [checked]
+        - text: SPEAK
+        - combobox "Kokoro voice":
+          - option "Kokoro voice loads on preparation" [selected]
+        - generic: VOICE AUTOMATION
+        - generic: 84%
+        - slider "Robotic voice effect intensity"
+        - generic: AUTO CADENCE
+        - generic: 90-180 SEC
+        - slider
+        - generic: AI and neural voice models load only when needed and are cached by the browser when supported.
+        - generic: GENERATIVE CHANNEL STANDBY
+        - generic: TV PRESENTATION
+        - generic: CAST-FRIENDLY 16:9
+        - checkbox "LOCK EXPERIENCE TO 16:9" [checked]
+        - text: LOCK EXPERIENCE TO 16:9
+        - generic: RENDER DENSITY
+        - generic: 1080P TARGET
+        - combobox:
+          - option "720P PERFORMANCE"
+          - option "1080P STANDARD" [selected]
+          - option "1440P HIGH"
+          - option "2160P ULTRA"
+        - generic: The scene keeps a canonical 16:9 layout on phones, PCs, and cast displays. Chrome still negotiates the final Cast stream resolution.
+        - generic: SLEEP TIMER
+        - generic: TIMER INACTIVE (CONTINUOUS)
+        - button "15M"
+        - button "30M"
+        - button "60M"
+        - button "OFF"
+        - generic: LCARD KEYPAD
+        - button "COM BADGE CHIRP"
+        - button "DOOR PNEUMATIC SWISH"
+        - button "BOSUN'S PIPE WHISTLE"
+        - button "MEDBAY ECG MONITOR"
+        - button "CARDASSIAN BULKHEAD DOOR"
+        - button "TURBOCHUTE WHOOSH"
+        - button "FABRICATOR SHIMMER"
+        - button "TRANSLOCATOR CYCLE"
+        - button "LCARD SINGLE CHIRP"
+    - contentinfo:
+      - generic: "SYSTEM STATUS: NORMAL"
+      - link "VIBE ENGINEERED BY LABYRICORN STUDIOS":
+        - /url: https://www.labyricorn.com/
+      - generic: "SPACE: PLAY/PAUSE | M: MUTE | ↑/↓: VOLUME"
+  - heading "Exhibit controls (61)" [level=2]
+  - generic "Capabilities"
+  - paragraph: Reported values are authoritative. New values are drafts; select Set or Invoke to submit. Rediscovery resets drafts.
+  - heading "audio" [level=3]
+  - article:
+    - heading "Master Volume" [level=3]
+    - code: mix.master
+    - paragraph: range · readable · writable
+    - status: "Reported value: 0.75"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "0.75"
+    - button "Set"
+  - article:
+    - heading "Hull Drone Level" [level=3]
+    - code: mix.hull.level
+    - paragraph: range · readable · writable
+    - status: "Reported value: 0.65"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "0.65"
+    - button "Set"
+  - article:
+    - heading "Hull Drone Frequency" [level=3]
+    - code: mix.hull.frequency
+    - paragraph: range · readable · writable
+    - status: "Reported value: 50"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "50"
+    - button "Set"
+  - article:
+    - heading "Hull Drone Cutoff" [level=3]
+    - code: mix.hull.cutoff
+    - paragraph: range · readable · writable
+    - status: "Reported value: 105"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "105"
+    - button "Set"
+  - article:
+    - heading "Drive / Core Level" [level=3]
+    - code: mix.drive.level
+    - paragraph: range · readable · writable
+    - status: "Reported value: 0.35"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "0.35"
+    - button "Set"
+  - article:
+    - heading "Drive Pulse Rate" [level=3]
+    - code: mix.drive.pulse-rate
+    - paragraph: range · readable · writable
+    - status: "Reported value: 48"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "48"
+    - button "Set"
+  - article:
+    - heading "Drive Carrier Frequency" [level=3]
+    - code: mix.drive.carrier
+    - paragraph: range · readable · writable
+    - status: "Reported value: 58"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "58"
+    - button "Set"
+  - article:
+    - heading "Environmental Airflow Level" [level=3]
+    - code: mix.environment.level
+    - paragraph: range · readable · writable
+    - status: "Reported value: 0.55"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "0.55"
+    - button "Set"
+  - article:
+    - heading "Environmental Filter Cutoff" [level=3]
+    - code: mix.environment.cutoff
+    - paragraph: range · readable · writable
+    - status: "Reported value: 1600"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "1600"
+    - button "Set"
+  - article:
+    - heading "Telemetry Level" [level=3]
+    - code: mix.telemetry.level
+    - paragraph: range · readable · writable
+    - status: "Reported value: 0.45"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "0.45"
+    - button "Set"
+  - article:
+    - heading "Telemetry Density" [level=3]
+    - code: mix.telemetry.density
+    - paragraph: range · readable · writable
+    - status: "Reported value: 0.65"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "0.65"
+    - button "Set"
+  - article:
+    - heading "Futuristic Noise Cancellation Level" [level=3]
+    - code: fnc.level
+    - paragraph: range · readable · writable
+    - status: "Reported value: 0.65"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "0.65"
+    - button "Set"
+  - article:
+    - heading "Futuristic Noise Cancellation Active" [level=3]
+    - code: fnc.enabled
+    - paragraph: state · readable · writable
+    - status: "Reported value: true"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - checkbox "New value" [checked]
+    - button "Set"
+  - heading "speech" [level=3]
+  - article:
+    - heading "Speech Robotic Modulation" [level=3]
+    - code: speech.robot-amount
+    - paragraph: range · readable · writable
+    - status: "Reported value: 0.84"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "0.84"
+    - button "Set"
+  - article:
+    - heading "Speak Text Line" [level=3]
+    - code: speech.say
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Generate Ambient AI Announcement" [level=3]
+    - code: speech.generate-announcement
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - heading "observation" [level=3]
+  - article:
+    - heading "Observation Visual Activity" [level=3]
+    - code: view.activity
+    - paragraph: range · readable · writable
+    - status: "Reported value: 0.6"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - spinbutton "New value": "0.6"
+    - button "Set"
+  - article:
+    - heading "Observation Viewport Active" [level=3]
+    - code: view.observation
+    - paragraph: state · readable · writable
+    - status: "Reported value: false"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - checkbox "New value"
+    - button "Set"
+  - article:
+    - heading "Starship Bezel Frame Framing" [level=3]
+    - code: view.viewport-frame
+    - paragraph: state · readable · writable
+    - status: "Reported value: true"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - checkbox "New value" [checked]
+    - button "Set"
+  - heading "transport" [level=3]
+  - article:
+    - heading "Audio Engine Online" [level=3]
+    - code: transport.playing
+    - paragraph: state · readable · writable
+    - status: "Reported value: false"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - checkbox "New value"
+    - button "Set"
+  - article:
+    - heading "Master Mute" [level=3]
+    - code: transport.muted
+    - paragraph: state · readable · writable
+    - status: "Reported value: false"
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - checkbox "New value"
+    - button "Set"
+  - heading "alert" [level=3]
+  - article:
+    - heading "Active Tactical Alert Status" [level=3]
+    - code: alert.active
+    - paragraph: selection · readable · writable
+    - status: "Reported value: \"none\""
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - combobox "New value":
+      - option "Condition Green (Normal)" [selected]
+      - option "Yellow Alert"
+      - option "Red Alert"
+    - button "Set"
+  - heading "universe" [level=3]
+  - article:
+    - heading "Active Sci-Fi Universe" [level=3]
+    - code: universe.selected
+    - paragraph: selection · readable · writable
+    - status: "Reported value: \"starfleet\""
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - combobox "New value":
+      - option "Starfleet / Galaxy" [selected]
+      - option "Whataverse / Tardix"
+      - option "Industrial / Weyland"
+      - option "Bioships / Leviathan"
+      - option "Retro Future / 1960s"
+      - option "Colonial Military"
+      - option "Deep Space Generation"
+      - option "Frontier & Salvage"
+      - option "Orbital Stations & Docks"
+      - option "Whimsical Fleet"
+    - button "Set"
+  - heading "preset" [level=3]
+  - article:
+    - heading "Active Audio Preset" [level=3]
+    - code: preset.selected
+    - paragraph: selection · readable · writable
+    - status: "Reported value: \"tng-bridge\""
+    - generic "Target descriptor"
+    - paragraph
+    - text: New value
+    - combobox "New value":
+      - 'option "Interprise-G: Main Bridge" [selected]'
+      - 'option "Interprise-G: Main Engineering"'
+      - 'option "Interprise-G: Crew Quarters"'
+      - 'option "USS Wayfarer: Bridge"'
+      - 'option "USS Wayfarer: Class-N Worp Core"'
+      - 'option "USS Defiance: Tactical Bridge"'
+      - 'option "Deep Space 8: Ops Center"'
+      - 'option "Interprise NCC-1701.5: Bridge (TOS)"'
+      - 'option "Interprise NCC-1701.5: Engineering (TOS)"'
+      - 'option "Interprise NS-01: Command Bridge"'
+      - option "1962 Classic Console (1st / 2nd Doctors)"
+      - option "Edwardian Secondary Console (4th Doctor)"
+      - option "The Coral Living TARDIX (9th / 10th Doctors)"
+      - option "The Bronze Workshop (11th Doctor)"
+      - option "The Cool Machine (12th Doctor)"
+      - option "The Humming Crystal Console (13th Doctor)"
+      - option "The Endless White (14th / 15th Doctors)"
+      - 'option "USCSS Nostramo: Ore Refinery Bridge"'
+      - 'option "Serenety: Firewing-Class Cargo Hold"'
+      - 'option "Red Dwarve: Main Drive Corridor"'
+      - 'option "Starbug Z: Cockpit Environment"'
+      - 'option "The Rasa: Dark Matter Bridge"'
+      - 'option "Rocinanta: Combat Ops & Epsilon Drive"'
+      - 'option "Hawk Translocator: Command Module"'
+      - 'option "Valley Foundry: Agro-Dome Forest Hub"'
+      - 'option "Meya: Leviathon Central Nexus"'
+      - 'option "Talym: Gunship Neural Bridge"'
+      - 'option "The Lexxi: Primary Organ Bridge"'
+      - 'option "Vorlan Cruiser: Sentient Core"'
+      - 'option "Wraithe Hive Ship: Throne Chamber"'
+      - 'option "Species 8675309: Fluid Bioship"'
+      - 'option "Jupiter Duece: Upper Deck Astrogator"'
+      - 'option "The Liberation: Zen Flight Bridge"'
+      - 'option "USS Cygnis: Victorian Engine Hall"'
+      - 'option "USS Palomina: Deep Research Pod"'
+      - 'option "Discovery Zero: Habitation Centrifuge"'
+      - 'option "Dim Star: Bomb Bay & Quarters"'
+      - 'option "Gunstarr: Tactical Combat Cockpit"'
+      - 'option "The Seeker: 25th Century Flagship"'
+      - 'option "USS Solaco: Conestega Hangar Deck"'
+      - 'option "Battlestar Galactica: Combat Information Center (CIC)"'
+      - 'option "Pale Star: Minbara/Vorlan Hybrid Bridge"'
+      - 'option "EAS Agamemnon II: Omega Destroyer Bridge"'
+      - 'option "Andromeda Ascending: Command Deck"'
+      - 'option "Excaliber: Triumph-Class Heavy Combat Core"'
+      - 'option "Colonial Adder Mk II: Cockpit Atmosphere"'
+      - 'option "The Avalin: Interstellar Cruise Concourse"'
+      - 'option "The Nightflier: Telepathic Corridor"'
+      - 'option "USS Ascention: Generation Ship Promenade"'
+      - 'option "Ark Zero: Evacuation Ark Bridge"'
+      - 'option "Icarus I: Solar Shield Core"'
+      - 'option "Event Boundary: Gravity Singularity Core"'
+      - 'option "Lewis & Clarke: Rescue Cutter Bridge"'
+      - 'option "The Betsy: Salvage Freighter Mess"'
+      - 'option "BeBoppa: Living Quarters & Hangar"'
+      - 'option "Outlaw Sun: Grapple Bridge"'
+      - 'option "Scorpius: Wanderer Salvage Vessel"'
+      - 'option "The Raider: Havoc Shuttle Bridge"'
+      - 'option "The Milan: M-Ship Cockpit Lounge"'
+      - 'option "Babylon 4: Core Control & Zocolo"'
+      - 'option "Moonbase Beta: Main Mission Control"'
+      - 'option "Sebastopol Station: Habitation Deck"'
+      - 'option "Tyco Station: Asteroid Construction Bay"'
+      - 'option "Ceres Minor Station: Sub-Crustal Tunnels"'
+      - 'option "Gatehouse Station: Quarantine Transfer Deck"'
+      - 'option "USS Norval: Command Bridge"'
+      - 'option "NSEA Protractor: Beryllium Orb Engine Room"'
+      - 'option "Heart of Silver: Unlikelihood Bridge"'
+      - 'option "HMS Camden Key: Flight Deck & Mess"'
+      - 'option "Spaceorb One: Mega-Warship Bridge"'
+    - button "Set"
+  - heading "display" [level=3]
+  - article:
+    - heading "Display Ticker Message (Transient)" [level=3]
+    - code: display.ticker
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - heading "event" [level=3]
+  - article:
+    - heading "Red Alert Impulse" [level=3]
+    - code: event.alert-red
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Warp Jump Impulse" [level=3]
+    - code: event.warp-jump
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Demat Cycle Impulse" [level=3]
+    - code: event.demat
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Time Vortex Impulse" [level=3]
+    - code: event.vortex
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Cloister Bell Impulse" [level=3]
+    - code: event.cloister
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Flak Barrage Impulse" [level=3]
+    - code: event.flak-barrage
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "FTL Jump Impulse" [level=3]
+    - code: event.ftl-jump
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Singularity Engage Impulse" [level=3]
+    - code: event.singularity
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Solar Flare Roar Impulse" [level=3]
+    - code: event.solar-roar
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Afterburner Ignite Impulse" [level=3]
+    - code: event.afterburner
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Ludicrous Speed Impulse" [level=3]
+    - code: event.ludicrous-speed
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Improbability Drive Flip" [level=3]
+    - code: event.improbability-flip
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - heading "sfx" [level=3]
+  - article:
+    - heading "Comm Badge Chime" [level=3]
+    - code: sfx.comm-badge
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Pneumatic Door Swish" [level=3]
+    - code: sfx.door-swish
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Bosun Pipe Call" [level=3]
+    - code: sfx.bosun-whistle
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Medical Vital Monitor" [level=3]
+    - code: sfx.medical-monitor
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Heavy Bulkhead Door" [level=3]
+    - code: sfx.cardassian-door
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Turbochute Whoosh" [level=3]
+    - code: sfx.turbolift
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Fabricator Materialize" [level=3]
+    - code: sfx.replicator
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Translocator Beam" [level=3]
+    - code: sfx.transporter
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Console Single Chirp" [level=3]
+    - code: sfx.console-chirp
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Sonic Acoustic Screwdriver" [level=3]
+    - code: sfx.sonic
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Console Mechanical Lever Clunk" [level=3]
+    - code: sfx.lever-clunk
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Tardix Wood & Lock Door" [level=3]
+    - code: sfx.tardix-door
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Demat Switch Rotor" [level=3]
+    - code: sfx.demat-switch
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Telepathic Circuit Chime" [level=3]
+    - code: sfx.telepathic-chime
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Air Handler Valve Thud" [level=3]
+    - code: sfx.air-handler
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Mag-Boot Solenoid Latch" [level=3]
+    - code: sfx.mag-boot
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Comlock Electronic Tone" [level=3]
+    - code: sfx.comlock
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Solar Radiation Wind" [level=3]
+    - code: sfx.solar-roar
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Cassette Magnetic Transport Clunk" [level=3]
+    - code: sfx.tape-clunk
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Thruster Burner Pulse" [level=3]
+    - code: sfx.afterburner
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Radiation Geiger Counter" [level=3]
+    - code: sfx.geiger
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Air Valve & Dock Clamp" [level=3]
+    - code: sfx.dock-clamp
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "Dradis Combat Sonar Ping" [level=3]
+    - code: sfx.dradis-ping
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - article:
+    - heading "HAL Logic Melodic Chime" [level=3]
+    - code: sfx.hal-chime
+    - paragraph: impulse · not readable · not writable
+    - status: No persistent value reported.
+    - generic "Target descriptor"
+    - paragraph
+    - button "Invoke"
+  - heading "Presentation surfaces" [level=2]: Presentation surfaces
+  - paragraph: Open Contract 5.3 presentation surfaces locally below. URLs resolve against the supplying exhibit. Disconnecting or switching exhibits closes these views. Remote/cast displays remain deferred.
+  - paragraph: No presentation surfaces advertised.
+  - heading "State and metadata" [level=2]
+  - button "Refresh state"
+  - generic "Session and exhibit metadata"
+  - generic "Current persistent state"
+  - heading "Protocol diagnostics" [level=2]
+  - generic "Incoming events"
+  - generic "Protocol and errors"
@@ -0,0 +1,180 @@
+Step 6.6 — Museum Gallery end-to-end validation through the NGN operator UI
+Server: pre-existing `npm start` server (node server/serve.js) on http://127.0.0.1:4173,
+        started before this session and left running. A second instance started for
+        validation failed with EADDRINUSE and exited; the served state was unchanged.
+NGN UI: http://127.0.0.1:4173/
+Exhibit: http://127.0.0.1:4173/test-fixtures/reference-exhibits/museum-gallery/control.html
+Replacement exhibit: http://127.0.0.1:4173/test-fixtures/reference-exhibits/scifi/index.html
+Method: live browser session against the served page; values read from the live DOM, the
+exhibit frames, and NGN's own diagnostics panes. No test doubles.
+
+--------------------------------------------------------------------
+1. Initial connection (Load exhibit)
+--------------------------------------------------------------------
+status: connected · synchronized
+identity: Museum Gallery · 0.1.0 · Contract 5.3
+metadata: { sessionId: "sess-1f54f",
+            contract: { major: 5, minor: 3 },
+            exhibit: { product: "Museum Gallery", version: "0.1.0", build: "reference-exhibit" },
+            registryRevision: 1, stateRevision: 0, sequence: null }
+capabilities: render: ready
+targets (5): artifact.selected (selection, r/w), lighting.level (range, r/w),
+             rotation.speed (range, r/w), labels.enabled (state, r/w),
+             action.spotlight-flash (impulse, not readable, not writable)
+state: { "artifact.selected": "the-orrery", "lighting.level": 0.6,
+         "rotation.speed": 0.4, "labels.enabled": true }
+error log: one SESSION entry, no errors
+
+--------------------------------------------------------------------
+2. Surface discovery and primary handling
+--------------------------------------------------------------------
+Presentation surfaces (3):
+  surface.control   Control Room      Primary      Role: control      URL: control.html
+  surface.artifact  Artifact Display  Non-primary  Role: ambient      URL: artifact.html
+  surface.info-wall Information Wall  Non-primary  Role: information  URL: info-wall.html
+Primary card buttons: Open disabled, Reload disabled, Close disabled
+Primary card status: "Open in the authoritative control frame. Use Connection controls to
+reload or disconnect."
+Non-primary panes rendered and each reported: "Attached to Control Room."
+Control Room readout "Attached non-primary surfaces": 2
+
+--------------------------------------------------------------------
+3. Lifecycle (participant count in the authoritative Control Room)
+--------------------------------------------------------------------
+open both      -> 2
+reload         -> 2
+reload again   -> 2
+close one      -> 1
+reopen         -> 2
+Reload freshness probe: a marker written to the secondary frame contentWindow was absent
+after reload (fresh document), and the document re-attached and re-rendered current state.
+
+--------------------------------------------------------------------
+4. Shared-state synchronization
+--------------------------------------------------------------------
+Control -> secondaries
+  Control Room combobox -> "star-map":
+    event { type: "selection.changed", sequence: 1, stateRevision: 1,
+            target: "artifact.selected", value: "star-map", source: "ui" }
+    Control Room "Star Map"; Artifact Display "Star Map"; Information Wall "Star Map"
+  Control Room lighting range -> 0.25:
+    event { type: "state.changed", sequence: 2, stateRevision: 2,
+            target: "lighting.level", value: 0.25, source: "ui" }
+    Control Room "25%"; Artifact Display "Lighting: 25%"
+
+Secondary -> primary -> secondaries
+  Real mouse click on Artifact Display "Cycle artifact" (authoritative value "star-map"):
+    Control Room combobox became "meteorite"; Control Room label "Meteorite Fragment"
+    event { type: "selection.changed", sequence: 3, stateRevision: 3,
+            target: "artifact.selected", value: "meteorite", source: "ui" }
+    Information Wall -> "Meteorite Fragment"; Artifact Display re-rendered authoritative result
+
+Sustained convergence (both secondaries open, alternating origins)
+  step 1 control select the-orrery   -> all views "The Orrery"      revision 7  count 2
+  step 2 info-wall toggle labels     -> labels.enabled true          revision 8  count 2
+  step 3 control rotation 0.6        -> rotation.speed 0.6           revision 9  count 2
+  step 4 artifact-display cycle      -> artifact.selected star-map   revision 10 count 2
+  Control Room, Artifact Display, Information Wall and NGN reported state all agreed
+  after every step.
+
+Late join
+  close Information Wall -> count 1
+  mutate: rotation 1.7, labels OFF -> stateRevision 5
+  reopen Information Wall -> immediately rendered "Meteorite Fragment" / "Labels: OFF",
+  count back to 2
+
+Reload recovery
+  mutate: lighting 0.9 -> stateRevision 6
+  reload Artifact Display -> fresh document returned with "Meteorite Fragment",
+  "Lighting: 90%", "Rotation: 1.7x" (current state, not defaults); count still 2
+
+--------------------------------------------------------------------
+5. NGN host commands
+--------------------------------------------------------------------
+Refresh state (state.get): succeeded; stateRevision 10, status connected · synchronized,
+                           no error
+set lighting.level = 0.35: succeeded; Control Room "35%" (range 0.35),
+                           Artifact Display "Lighting: 35%";
+                           event { type: "state.changed", sequence: 11, stateRevision: 11,
+                                   target: "lighting.level", value: 0.35,
+                                   source: "host", correlationId: "ngn-2-4" }
+set artifact.selected = meteorite: succeeded; Control Room / Artifact Display /
+                           Information Wall all "Meteorite Fragment";
+                           event { type: "selection.changed", sequence: 12, stateRevision: 12,
+                                   target: "artifact.selected", value: "meteorite",
+                                   source: "host", correlationId: "ngn-2-6" }
+invoke action.spotlight-flash: succeeded;
+                           event { type: "action.executed", sequence: 13,
+                                   target: "action.spotlight-flash", args: {},
+                                   source: "host", correlationId: "ngn-2-8" };
+                           exhibit gallery.spotlightFlashCount incremented;
+                           Control Room and both secondaries announcement nodes flashed
+                           "Spotlight flashed." (captured by a DOM mutation observer on the
+                           Artifact Display announcement node: seen transitions
+                           ["Spotlight flashed.", "Waiting for shared state."])
+
+--------------------------------------------------------------------
+6. Reconnect and exhibit replacement
+--------------------------------------------------------------------
+Disconnect:
+  status: disconnected · not synchronized
+  catalog: "Connect an exhibit to discover its controls."
+  surfaces: "No presentation surfaces advertised."; surface cards 0; surface iframes 0
+  control frame removed; state {}; metadata all null; no error entries
+Reconnect:
+  status: connected · synchronized; session sess-15cf1; contract { major: 5, minor: 3 }
+  targets (5); surfaces (3) with surface.control primary; participant count 0
+  no stale panes; both secondaries reopened -> "Attached to Control Room.", count 2
+Switch to SciFi:
+  identity: SciFi-XZBT · 5.2.0 · Contract 5.3
+  metadata: sessionId "sess-2akzu3a7", contract { major: 5, minor: 3 },
+            registryRevision 1, stateRevision 0
+  status: connected · synchronized; targets (61); surfaces: none advertised
+  iframes referencing museum-gallery: 0
+Switch back to Museum Gallery:
+  session sess-126c6; contract { major: 5, minor: 3 }; targets (5); surfaces (3) with
+  correct primary; participant count 0; iframes referencing scifi: 0
+  state: fresh exhibit defaults, stateRevision 0
+
+--------------------------------------------------------------------
+7. Failure isolation (live)
+--------------------------------------------------------------------
+Artifact Display document globals:
+  XZBTContractCore: undefined
+  MuseumGalleryContract: undefined
+  MuseumGalleryExhibit: undefined
+  XZBTHostTransport: undefined
+  MuseumGallerySurfaceBus: present
+  __museumGalleryDebug.core: absent
+Forged protocol messages posted directly to the secondary window:
+  { xzbt: "5.3", type: "hello", requestId: "probe-secondary", supportedContractMajors: [5] }
+  { xzbt: "5.3", type: "set", requestId: "probe-set", sessionId: "x",
+    target: "artifact.selected", value: "meteorite" }
+  -> responses received: none; authoritative selection unchanged ("The Orrery")
+Surface-local failure: Artifact Display frame navigated to
+  /test-fixtures/reference-exhibits/museum-gallery/does-not-exist.html (served "Not found")
+  -> NGN status stayed "connected · synchronized" on session sess-126c6;
+     control frame still control.html; registry/state unaffected; no error entry;
+     participant count 2 -> 0 with no stale entry
+NGN per-surface Reload on the failed pane:
+  -> frame back at artifact.html, "Attached to Control Room.", participant count 1,
+     session still synchronized, no error entry
+
+Automated-only isolation evidence (not re-injected live): malformed/invalid descriptor
+catalogs, isolated HTTP/frame/reload failures, external frame removal detection, stalled
+surface resource, redirect refusal on resource check, presentation-window impersonation
+refusal, transport source/origin validation.
+
+--------------------------------------------------------------------
+8. Automated verification
+--------------------------------------------------------------------
+Focused: node --test tests/museum-gallery.test.js tests/local-surfaces.test.js
+                   tests/surface-validation.test.js tests/postmessage-interop.test.js
+                   tests/connection.test.js
+  tests 107 / pass 107 / fail 0
+
+Full: node --test
+  tests 129 / pass 129 / fail 0
+
+git diff --check -> clean (exit 0)
+python devlog_editor.py --validate -> devlog-editor: devlog is valid (exit 0)
@@ -1,5 +1,5 @@
 /*
- * Aquarium — XZBT Exhibit Contract 5.2 adapter.
+ * Aquarium — XZBT Exhibit Contract 5.3 adapter.
 *
 * This file is the only place in the exhibit that knows the contract exists.
 * It does three things and nothing else:
@@ -1,5 +1,5 @@
 /*
- * Haunted House — XZBT Exhibit Contract 5.2 adapter.
+ * Haunted House — XZBT Exhibit Contract 5.3 adapter.
 *
 * This adapter is the one that has to be honest about capabilities. The
 * exhibit's audio engine cannot start until the browser has seen a user
@@ -71,6 +71,16 @@
    link.mutate('set', 'artifact.selected', next);
  });

+  /* `beforeunload` is best-effort only -- it does not reliably fire when
+   * NGN removes/replaces this frame's iframe element directly (as opposed
+   * to a real navigation), so it is not the correctness mechanism here.
+   * `__xzbtSurfaceDispose` is a well-known, optional hook: local-surfaces.js
+   * calls it synchronously, if present, on this frame's contentWindow right
+   * before removing the iframe -- deterministic because it is a direct
+   * same-origin call, not a queued postMessage that a doomed frame might
+   * never get to process. detach() is idempotent, so it is safe for both
+   * this hook and beforeunload to fire (or neither, or either alone). */
+  window.__xzbtSurfaceDispose = function () { link.detach(); };
  window.addEventListener('beforeunload', function () { link.detach(); });
  window.__museumGalleryDebug = { link: link };
 })();
@@ -126,11 +126,12 @@
      setters: setters,
      readers: readers,
      actions: actions,
-      surfaces: surfaces,
-      /* Contract 5.3 adoption is per-instance; every other reference exhibit
-       * keeps the shared core's Contract 5.2 defaults untouched. */
-      contractMinor: 3,
-      xzbtVersion: '5.3'
+      /* contractMinor/xzbtVersion are intentionally omitted: the shared
+       * contract-core.js now defaults every exhibit to Contract 5.3, and
+       * Museum Gallery has no reason to override that default. `surfaces`
+       * is the one thing that makes this exhibit's contract usage different
+       * from the others -- Contract 5.3 §31 presentation surfaces. */
+      surfaces: surfaces
    });

    return core;
@@ -81,12 +81,17 @@
   * surface) to attached surfaces, and answers their attach requests with a
   * fresh snapshot read straight from this Core -- never a second
   * computation. */
-  var bus = window.MuseumGallerySurfaceBus.createOwner(core);
+  function updateSubscriberCount(count) {
+    Shell.setText(subscriberCountEl, String(count));
+  }
+  var bus = window.MuseumGallerySurfaceBus.createOwner(core, {
+    onConnectionChange: updateSubscriberCount
+  });
+  updateSubscriberCount(bus.attachedCount());
  var priorOnEvent = core.onEvent;
  core.onEvent = function (event) {
    if (typeof priorOnEvent === 'function') priorOnEvent(event);
    sync();
-    Shell.setText(subscriberCountEl, String(bus.attachedCount()));
  };

  /* Optional NGN attachment -- same optional transport every reference
@@ -56,6 +56,12 @@
    link.mutate('set', 'labels.enabled', !latest['labels.enabled']);
  });

+  /* Same rationale as artifact.boot.js: `__xzbtSurfaceDispose` is the
+   * deterministic path (called synchronously by local-surfaces.js right
+   * before it removes this frame); `beforeunload` remains only as a
+   * best-effort fallback for the cases NGN can't foresee (e.g. the tab
+   * closing on its own). detach() is idempotent either way. */
+  window.__xzbtSurfaceDispose = function () { link.detach(); };
  window.addEventListener('beforeunload', function () { link.detach(); });
  window.__museumGalleryDebug = { link: link };
 })();
@@ -39,23 +39,42 @@
   * second computation of state.
   *
   * @param {object} core an XZBTContractCore.ContractCore instance
+   * @param {object} [options]
+   * @param {function} [options.onConnectionChange] (attachedCount)
   */
-  function createOwner(core) {
+  function createOwner(core, options) {
+    options = options || {};
    var channel = new BroadcastChannel(CHANNEL_NAME);
-    var attachedCount = 0;
+    /* Participant bookkeeping is identity-based (a Set of live participant
+     * ids), not a bare counter. This is what makes it idempotent: a
+     * duplicate `attach` from a still-live participant cannot inflate the
+     * count, and a `detach` for an id that is not (or no longer) present
+     * cannot underflow it -- both matter because iframe reload/removal can
+     * make attach/detach delivery imperfect (see attach()'s participantId
+     * and local-surfaces.js's pre-removal dispose call). */
+    var participants = new Set();
+
+    function notifyConnectionChange() {
+      if (typeof options.onConnectionChange === 'function') {
+        options.onConnectionChange(participants.size);
+      }
+    }

    channel.onmessage = function (ev) {
      var msg = ev.data;
      if (!msg || typeof msg !== 'object') return;

      if (msg.type === 'attach') {
-        attachedCount += 1;
+        if (typeof msg.participantId === 'string') {
+          participants.add(msg.participantId);
+        }
        channel.postMessage({
          type: 'attach.snapshot',
          inReplyTo: msg.requestId,
          snapshot: core.stateSnapshot(),
          registryRevision: core.registryRevision
        });
+        notifyConnectionChange();
        return;
      }

@@ -75,7 +94,13 @@
      }

      if (msg.type === 'detach') {
-        attachedCount = Math.max(0, attachedCount - 1);
+        /* A detach with no/unknown participantId (a stray legacy message, a
+         * duplicate, or one that arrives after that id was already removed)
+         * is a no-op -- Set.delete() only reports and fires the callback
+         * when it actually removed something live. */
+        if (typeof msg.participantId === 'string' && participants.delete(msg.participantId)) {
+          notifyConnectionChange();
+        }
      }
    };

@@ -87,7 +112,7 @@

    return {
      channel: channel,
-      attachedCount: function () { return attachedCount; },
+      attachedCount: function () { return participants.size; },
      close: function () { channel.close(); }
    };
  }
@@ -109,7 +134,14 @@
    options = options || {};
    var channel = new BroadcastChannel(CHANNEL_NAME);
    var requestId = randomId();
+    /* A stable identity for THIS attachment (this document load, this
+     * BroadcastChannel instance). A reload creates a brand-new attach() call
+     * and therefore a brand-new participantId, which is exactly what lets
+     * the owner's Set-based bookkeeping retire the old identity and adopt
+     * the new one without the two ever being confused for each other. */
+    var participantId = randomId();
    var attached = false;
+    var detached = false;

    var timer = setTimeout(function () {
      if (attached) return;
@@ -134,7 +166,21 @@
      }
    };

-    channel.postMessage({ type: 'attach', requestId: requestId });
+    channel.postMessage({ type: 'attach', requestId: requestId, participantId: participantId });
+
+    function detach() {
+      /* Idempotent: local-surfaces.js's deterministic pre-removal dispose
+       * call and this document's own best-effort `beforeunload` handler can
+       * both end up calling detach() for the same attachment. Only the
+       * first actually posts a message; every call still tears down the
+       * timer/channel so repeated calls are always safe. */
+      if (attached && !detached) {
+        detached = true;
+        channel.postMessage({ type: 'detach', participantId: participantId });
+      }
+      clearTimeout(timer);
+      channel.close();
+    }

    return {
      channel: channel,
@@ -148,11 +194,7 @@
        channel.postMessage(payload);
        return true;
      },
-      detach: function () {
-        if (attached) channel.postMessage({ type: 'detach' });
-        clearTimeout(timer);
-        channel.close();
-      }
+      detach: detach
    };
  }

@@ -1,5 +1,5 @@
 /*
- * Planetarium — XZBT Exhibit Contract 5.2 adapter.
+ * Planetarium — XZBT Exhibit Contract 5.3 adapter.
 *
 * Declares the catalog, binds targets to real exhibit services, and routes
 * the native UI through the canonical mutation path. No state of its own.
@@ -2428,3 +2428,30 @@ body.xzbt-tv-aspect .observation-overlay:not(.active){display:none}
@media (max-width:700px){
  .watch-experience-wrap{min-width:150px}.watch-experience-help{font-size:.54rem}
 }
+
+/* ==========================================================================
+   Step 6.7B -- Observation surface mode (body.surface-observation).
+   Applied when this document is booted as the non-authoritative Observation
+   surface (?surface=observation&xi=...). Presentation-only: additive rules,
+   nothing above this block is touched. The console DOM (header/main) is
+   hidden rather than removed -- observation-engine.js keeps binding to it
+   exactly as it does today, unmodified, per the Step 6.7A design.
+   ========================================================================== */
+body.surface-observation > header,
+body.surface-observation > main {
+  display: none !important;
+}
+
+body.surface-observation .observation-overlay {
+  position: fixed;
+  inset: 0;
+  z-index: 1;
+}
+
+/* Exiting/returning to the console is NGN's job (pane lifecycle), not the
+   surface's -- these controls would otherwise mutate the *console's* own
+   view.observation overlay flag from a stray click (report SS7/SS8). */
+body.surface-observation #obs-btn-exit,
+body.surface-observation #observation-return-pill {
+  display: none !important;
+}
@@ -440,6 +440,8 @@
  <script src="js/observation-bezels.js"></script>
  <script src="js/observation-engine.js"></script>
  <script src="js/control-bus.js"></script>
+  <script src="js/surface-mode.js"></script>
+  <script src="js/surface-bus.js"></script>
  <script src="js/generative-experience.js"></script>
  <script src="js/contract-adapter.js"></script>
  <script src="js/app.js"></script>
@@ -5,6 +5,20 @@
 */

 document.addEventListener('DOMContentLoaded', () => {
+  // Step 6.7B: boot-mode resolver (Contract 5.3 SS31.4 query-string surface
+  // form). 'console' is today's application, byte-for-byte -- the resolver
+  // returns 'console' for no query string and for any unrecognized
+  // ?surface= value. 'observation' renders only the Observation viewscreen
+  // and mirrors an authoritative console instance over an exhibit-internal
+  // BroadcastChannel; it never constructs a second contract session, audio
+  // graph or generative engine (see the isConsoleMode guards below).
+  const xzbtSurface = XZBTSurfaceMode.resolve(window.location);
+  const isConsoleMode = xzbtSurface.mode !== 'observation';
+  const xzbtInstanceId = isConsoleMode ? XZBTSurfaceMode.newInstanceId() : xzbtSurface.instanceId;
+  if (!isConsoleMode) document.body.classList.add('surface-observation');
+  let surfaceOwner = null; // console mode: bus owner, feeds attached surfaces
+  let surfaceLink = null;  // observation mode: bus attachment to the console
+
  // 1. Initialize Audio Subsystems
  const audioManager = new AudioManager();
  const fncSystem = new FuturisticNoiceCancellation(audioManager);
@@ -21,7 +35,9 @@ document.addEventListener('DOMContentLoaded', () => {
  window.expandedAudio = expandedAudio;
  window.whataverseAudio = whataverseAudio;
  window.engineTransitions = engineTransitions;
-  const visualizer = new StarshipVisualizer(audioManager, warpCore);
+  // Step 6.7B: console-only. Its canvases (spectrum, warp core) are
+  // console-panel elements; never construct it on the Observation surface.
+  const visualizer = isConsoleMode ? new StarshipVisualizer(audioManager, warpCore) : null;
  const observationEngine = new ObservationEngine(audioManager, warpCore, alerts, hullDrone, lifeSupport);
  window.observationEngine = observationEngine;

@@ -97,34 +113,55 @@ document.addEventListener('DOMContentLoaded', () => {
  const timerDisplay = document.getElementById('timer-display');
  const timerButtons = document.querySelectorAll('.btn-timer');

-  // XZBT Generative Experience subsystem. Deterministic engine remains authoritative.
-  const generativeExperience = new XZBTGenerativeExperience({
-    getUniverse: () => UniverseRegistry[activeUniverseId],
-    getPreset: () => UniverseRegistry[activeUniverseId]?.presets?.[activePresetId] || null,
-    isPlaying: () => isPlaying,
-    isObservation: () => observationActive,
-    audioManager,
-    onGenerated: (line, state) => {
-      const ticker = document.getElementById('observation-ticker-text');
-      if (ticker && observationActive) ticker.textContent = line.toUpperCase();
-      window.dispatchEvent(new CustomEvent('xzbt:generated-content', { detail: { line, state } }));
-    }
-  });
-  generativeExperience.bindUI();
-  window.generativeExperience = generativeExperience;
+  // XZBT Generative Experience subsystem. Deterministic engine remains
+  // authoritative. Step 6.7B: console-only -- WebLLM/Kokoro must never be
+  // constructed or prepared on the Observation surface (highest-risk guard
+  // in this design; see the isConsoleMode guard on prepareExperience() in
+  // enterObservation() below).
+  let generativeExperience = null;
+  if (isConsoleMode) {
+    generativeExperience = new XZBTGenerativeExperience({
+      getUniverse: () => UniverseRegistry[activeUniverseId],
+      getPreset: () => UniverseRegistry[activeUniverseId]?.presets?.[activePresetId] || null,
+      isPlaying: () => isPlaying,
+      isObservation: () => observationActive,
+      audioManager,
+      onGenerated: (line, state) => {
+        const ticker = document.getElementById('observation-ticker-text');
+        const tickerText = line.toUpperCase();
+        if (ticker && observationActive) ticker.textContent = tickerText;
+        // Mirror the announcement to any attached Observation surface(s):
+        // the AI only verbalizes state the authority already decided, so
+        // this is presentation-only text, not contract state (report SS6).
+        if (surfaceOwner) surfaceOwner.broadcastPresentation('ticker', { tickerText });
+        window.dispatchEvent(new CustomEvent('xzbt:generated-content', { detail: { line, state } }));
+      }
+    });
+    generativeExperience.bindUI();
+    window.generativeExperience = generativeExperience;
+  }

  // Forward-declare absolute state setters & helpers for Contract Adapter
  let setMasterVolumeDirect, setPlayingDirect, setMutedDirect, setFncEnabledDirect;
  let setObservationDirect, setViewportFrameDirect, setAlertActiveDirect;
  let setUniverseDirect, selectPresetDirect, getContractStateSnapshot;
+  // Step 6.7B: console-only. Never constructed on the Observation surface --
+  // this is what makes "no second contract session" a structural fact.
+  let controlBus = null;
+  let contractAdapter = null;

-  // Semantic control bus & XZBT Contract Adapter
-  const controlBus = new XZBTControlBus();
+  // Semantic control bus & XZBT Contract Adapter. Step 6.7B: constructed
+  // only in console mode -- see the isConsoleMode guard closing after
+  // generativeExperience.onSpeechStateChanged below.
+  if (isConsoleMode) {
+  controlBus = new XZBTControlBus();
  window.xzbtControlBus = controlBus;

-  const contractAdapter = new XZBTContractAdapter({
+  contractAdapter = new XZBTContractAdapter({
    product: 'SciFi-XZBT',
-    version: '5.2.0',
+    version: '5.3.0',
+    surfaces: XZBTSurfaceMode.SURFACES(xzbtInstanceId),
+    instanceId: xzbtInstanceId,
    bindings: {
      getUniverse: () => activeUniverseId,
      getPreset: () => activePresetId,
@@ -203,7 +240,21 @@ document.addEventListener('DOMContentLoaded', () => {
        'fnc.enabled': (v, src) => setFncEnabledDirect(v, src),
        'view.observation': (v, src) => setObservationDirect(v, src),
        'view.viewport-frame': (v, src) => setViewportFrameDirect(v, src),
-        'alert.active': (v, src) => setAlertActiveDirect(v, src)
+        'alert.active': (v, src) => setAlertActiveDirect(v, src),
+        // Step 6.7B: newly-canonical targets. observation-engine.js keeps
+        // setPillars(); warp-flight has no engine-side setter (only
+        // toggleWarpFlight()), so the desired boolean is compared against
+        // the engine's current flightMode before toggling -- this keeps
+        // observation-engine.js's own simulation code untouched.
+        'view.pillars': v => {
+          if (observationEngine) observationEngine.setPillars(!!v);
+        },
+        'view.warp-flight': v => {
+          if (!observationEngine) return;
+          const want = !!v;
+          const isWarp = observationEngine.flightMode === 'warp';
+          if (want !== isWarp) observationEngine.toggleWarpFlight();
+        }
      },
      invokers: {
        'speech.say': async args => {
@@ -252,43 +303,130 @@ document.addEventListener('DOMContentLoaded', () => {
    }
  });
  window.xzbtContractAdapter = contractAdapter;
-  fncSystem.onMutation = (id, value) => contractAdapter.applyMutation(id, value, 'ui');
-  generativeExperience.onMutation = (id, value) => contractAdapter.applyMutation(id, value, 'ui');
-  generativeExperience.onInvoke = id => contractAdapter.invokeAction(id, {}, 'ui');
-  generativeExperience.onSpeechStateChanged = state => contractAdapter.updateCapability('speech', state);
-  observationEngine.onMutation = (id, value) => contractAdapter.applyMutation(id, value, 'ui');
+  fncSystem.onMutation = (id, value) => contractAdapter?.applyMutation(id, value, 'ui');
+  generativeExperience.onMutation = (id, value) => contractAdapter?.applyMutation(id, value, 'ui');
+  generativeExperience.onInvoke = id => contractAdapter?.invokeAction(id, {}, 'ui');
+  generativeExperience.onSpeechStateChanged = state => contractAdapter?.updateCapability('speech', state);

+  // Step 6.7B: exhibit-internal surface-attachment bus, owner side. Fed
+  // from the adapter's session-independent onLocalChange/onLocalAction
+  // hooks (contract-adapter.js SS5.4) rather than contract events, which are
+  // gated on an NGN session and would go silent standalone.
+  surfaceOwner = XZBTSurfaceBus.createOwner(contractAdapter, {
+    channelName: XZBTSurfaceMode.channelName(xzbtInstanceId),
+    // A surface attaching/detaching can flip observationAudienceActive();
+    // re-evaluate the scheduler so a pane opened with the console overlay
+    // off (or the last pane closing with it still off) starts/stops the
+    // ambient generator correctly (report SS6, SS8's symmetric detach case).
+    onParticipantsChanged: () => scheduleObservationAmbientActivity()
+  });
+  contractAdapter.onLocalChange = (target, value, stateRevision) => {
+    surfaceOwner.broadcastState(target, value, stateRevision);
+  };
+  contractAdapter.onLocalAction = (target, args) => {
+    surfaceOwner.broadcastAction(target, args);
+  };
+  } else {
+    // Step 6.7B: Observation surface (non-authoritative). Never constructs
+    // a contract session, control bus, or generative engine; attaches to
+    // the console instance named by ?xi= and mirrors its state over the
+    // exhibit-internal bus. `applyPresentationState` is defined further
+    // down (function declarations hoist; these callbacks only actually run
+    // once a message arrives, long after the rest of this script has run).
+    surfaceLink = XZBTSurfaceBus.attach({
+      channelName: XZBTSurfaceMode.channelName(xzbtInstanceId),
+      timeoutMs: 1500,
+      onSnapshot: (values, stateRevision, registryRevision, presentation) => {
+        Object.keys(values || {}).forEach(target => applyPresentationState(target, values[target]));
+        if (presentation && typeof presentation.tickerText === 'string' && presentation.tickerText) {
+          const ticker = document.getElementById('observation-ticker-text');
+          if (ticker) ticker.textContent = presentation.tickerText;
+        }
+        // The surface renders the scene unconditionally while open -- no
+        // view.observation gating (report SS8: surface existence and the
+        // console's own overlay flag are deliberately separate concepts).
+        enterObservation();
+      },
+      onChange: (target, value) => applyPresentationState(target, value),
+      onAction: (target, args) => {
+        if (target === 'display.ticker' && args && typeof args.text === 'string') {
+          const ticker = document.getElementById('observation-ticker-text');
+          if (ticker) ticker.textContent = args.text;
+        }
+      },
+      onPresentation: (kind, payload) => {
+        if (kind === 'ticker' && typeof payload.tickerText === 'string') {
+          const ticker = document.getElementById('observation-ticker-text');
+          if (ticker) ticker.textContent = payload.tickerText;
+        } else if (kind === 'obs-activity') {
+          // Render the authority's decision; never independently generate
+          // one (report SS6's "authority decides, surface renders").
+          triggerObservationActivity(payload.source || 'ambient');
+        }
+      },
+      onTimeout: () => {
+        // No console instance open on this channel (or a stale/unknown
+        // ?xi=). Degrade to a clear waiting state rather than inventing
+        // local authority (report SS9, Museum's proven behavior).
+        console.warn('[SciFi-XZBT] Observation surface: no console instance found for xi=' + xzbtInstanceId);
+      }
+    });
+
+    window.__xzbtSurfaceDispose = () => { if (surfaceLink) surfaceLink.detach(); };
+    window.addEventListener('beforeunload', () => { if (surfaceLink) surfaceLink.detach(); });
+  } // end isConsoleMode / else observation-surface attach (control bus, contract adapter, surface bus)
+
+  // Step 6.7B: the one dock-interaction chokepoint (already true before this
+  // step for every control except PILLARS/WARP, now including them). Console
+  // mode routes into the one mutation chokepoint as before; the Observation
+  // surface routes the same five interactive controls to the console over the
+  // bus instead, and drops view.observation (RETURN) locally -- posting it
+  // would toggle the *console's* own overlay, a cross-surface side effect
+  // the design explicitly forbids (report SS8). RETURN/exit are additionally
+  // hidden by CSS (body.surface-observation) as the primary defense.
+  const XZBT_PRESENTATION_ROUTED_TARGETS = new Set([
+    'view.warp-flight', 'view.viewport-frame', 'view.pillars', 'alert.active', 'preset.selected'
+  ]);
+  observationEngine.onMutation = isConsoleMode
+    ? (id, value) => contractAdapter?.applyMutation(id, value, 'ui')
+    : (id, value) => {
+        if (!XZBT_PRESENTATION_ROUTED_TARGETS.has(id)) return;
+        if (surfaceLink) surfaceLink.mutate('set', id, value);
+      };
+
+  // Step 6.7B: console-only (controlBus/contractAdapter don't exist otherwise).
+  if (isConsoleMode) {
  // Intercept XZBTControlBus calls to route through contractAdapter
  const origBusSet = controlBus.set.bind(controlBus);
  const origBusTrigger = controlBus.trigger.bind(controlBus);
  controlBus.set = function (id, value, source = 'external') {
-    if (contractAdapter.legacyIdMap.has(id) || contractAdapter.targets.has(id)) {
-      const canonicalId = contractAdapter.legacyIdMap.get(id) || id;
-      const target = contractAdapter.targets.get(canonicalId);
+    if (contractAdapter?.legacyIdMap.has(id) || contractAdapter?.targets.has(id)) {
+      const canonicalId = contractAdapter?.legacyIdMap.get(id) || id;
+      const target = contractAdapter?.targets.get(canonicalId);
      let normVal = value;
      if (target && target.kind === 'range') {
-        if (contractAdapter.legacyIdMap.has(id)) {
+        if (contractAdapter?.legacyIdMap.has(id)) {
          const legacy = controlBus.targets.get(id);
          if (legacy?.step) normVal = Math.round(Number(value) / legacy.step) * legacy.step;
          if (canonicalId === 'view.activity') normVal = Number(normVal) / 100;
        }
      }
-      contractAdapter.applyMutation(canonicalId, normVal, source);
+      contractAdapter?.applyMutation(canonicalId, normVal, source);
      return true;
    }
    return origBusSet(id, value, source);
  };
  controlBus.trigger = function (id, source = 'external') {
-    if (contractAdapter.legacyIdMap.has(id) || contractAdapter.targets.has(id)) {
-      const canonicalId = contractAdapter.legacyIdMap.get(id) || id;
-      const target = contractAdapter.targets.get(canonicalId);
+    if (contractAdapter?.legacyIdMap.has(id) || contractAdapter?.targets.has(id)) {
+      const canonicalId = contractAdapter?.legacyIdMap.get(id) || id;
+      const target = contractAdapter?.targets.get(canonicalId);
      if (target && target.kind === 'state') {
        // Toggle state if boolean
-        const curr = contractAdapter.getContractState()[canonicalId];
-        contractAdapter.applyMutation(canonicalId, !curr, source);
+        const curr = contractAdapter?.getContractState()[canonicalId];
+        contractAdapter?.applyMutation(canonicalId, !curr, source);
        return true;
      }
-      contractAdapter.invokeAction(canonicalId, {}, source);
+      contractAdapter?.invokeAction(canonicalId, {}, source);
      return true;
    }
    return origBusTrigger(id, source);
@@ -331,6 +469,7 @@ document.addEventListener('DOMContentLoaded', () => {
  controlBus.register('red-alert', { label: 'Red Alert Toggle', type: 'action' });
  controlBus.register('generate-announcement', { label: 'Generate AI Announcement', type: 'action' });
  controlBus.register('mute', { label: 'Master Mute', type: 'action' });
+  } // end isConsoleMode (control bus semantic registration)


  // TV presentation controls. The final Cast stream quality remains Chrome-controlled.
@@ -365,7 +504,7 @@ document.addEventListener('DOMContentLoaded', () => {
      btn.innerHTML = `<span class="u-icon">${u.icon}</span> <span>${u.name}</span>`;
      btn.addEventListener('click', (e) => {
        e.stopPropagation();
-        contractAdapter.applyMutation('universe.selected', u.id, 'ui');
+        contractAdapter?.applyMutation('universe.selected', u.id, 'ui');
      });
      universeDropdown.appendChild(btn);
    });
@@ -399,6 +538,8 @@ document.addEventListener('DOMContentLoaded', () => {
    document.body.className = universe.themeClass;
    // Assigning className wholesale drops the TV presentation classes, so re-apply them.
    applyTV();
+    // ...and the Step 6.7B surface-mode class, for the same reason.
+    if (!isConsoleMode) document.body.classList.add('surface-observation');
    headerMatrixLabel.textContent = universe.headerTitle;

    // Custom titles per universe
@@ -472,7 +613,7 @@ document.addEventListener('DOMContentLoaded', () => {
    soundboardTitle.textContent = conf.soundboard;

    // Configure Visualizer mode
-    visualizer.setMode(universe.visualizer || 'warp-core');
+    visualizer?.setMode(universe.visualizer || 'warp-core');

    // Render Event Buttons & Soundboard
    renderUniverseEvents(universe);
@@ -509,10 +650,10 @@ document.addEventListener('DOMContentLoaded', () => {
  async function invokeConsoleEvent(evt, btn, source) {
    if (evt.type === 'alert-red' || evt.type === 'alert-yellow') {
      const value = evt.type === 'alert-red' ? 'red' : 'yellow';
-      return contractAdapter.applyMutation('alert.active', alerts.activeAlert === value ? 'none' : value, source);
+      return contractAdapter?.applyMutation('alert.active', alerts.activeAlert === value ? 'none' : value, source);
    }
-    const canonical = [...contractAdapter.targets.values()].find(t => t.kind === 'impulse' && t.id.startsWith('event.') && (t.id === `event.${evt.type}` || `btn-${t.id.slice(6)}` === evt.id));
-    if (canonical) return contractAdapter.invokeAction(canonical.id, {}, source);
+    const canonical = [...contractAdapter?.targets.values()].find(t => t.kind === 'impulse' && t.id.startsWith('event.') && (t.id === `event.${evt.type}` || `btn-${t.id.slice(6)}` === evt.id));
+    if (canonical) return contractAdapter?.invokeAction(canonical.id, {}, source);
    await audioManager.resume();
    handleUniverseEvent(evt.type, btn);
  }
@@ -531,7 +672,7 @@ document.addEventListener('DOMContentLoaded', () => {
      btn.addEventListener('click', async () => {
        const aliases = { 'btn-chirp-single': 'sfx.console-chirp', 'btn-telepathic': 'sfx.telepathic-chime', 'btn-commlock': 'sfx.comlock', 'btn-afterburner-snd': 'sfx.afterburner' };
        const canonical = aliases[key.id] || `sfx.${key.id.replace(/^btn-/, '')}`;
-        if (contractAdapter.targets.has(canonical)) return contractAdapter.invokeAction(canonical, {}, 'ui');
+        if (contractAdapter?.targets.has(canonical)) return contractAdapter?.invokeAction(canonical, {}, 'ui');
        await audioManager.resume();
        handleSoundboardTrigger(key.id);
      });
@@ -553,7 +694,7 @@ document.addEventListener('DOMContentLoaded', () => {
      `;

      btn.addEventListener('click', () => {
-        contractAdapter.applyMutation('preset.selected', preset.id, 'ui');
+        contractAdapter?.applyMutation('preset.selected', preset.id, 'ui');
      });

      presetContainer.appendChild(btn);
@@ -763,7 +904,7 @@ document.addEventListener('DOMContentLoaded', () => {
  }

  btnPlay.addEventListener('click', () => {
-    contractAdapter.applyMutation('transport.playing', !isPlaying, 'ui');
+    contractAdapter?.applyMutation('transport.playing', !isPlaying, 'ui');
  });

  // 6. Master Volume Control System
@@ -800,65 +941,65 @@ document.addEventListener('DOMContentLoaded', () => {
  }

  function setMasterVolume(val) {
-    contractAdapter.applyMutation('mix.master', val, 'ui');
+    contractAdapter?.applyMutation('mix.master', val, 'ui');
  }

  function toggleMute() {
-    contractAdapter.applyMutation('transport.muted', !audioManager.isMuted, 'ui');
+    contractAdapter?.applyMutation('transport.muted', !audioManager.isMuted, 'ui');
  }

  sliderMasterVol.addEventListener('input', (e) => {
-    contractAdapter.applyMutation('mix.master', parseFloat(e.target.value), 'ui');
+    contractAdapter?.applyMutation('mix.master', parseFloat(e.target.value), 'ui');
  });
  btnMasterMute.addEventListener('click', toggleMute);
  btnHeaderMute.addEventListener('click', toggleMute);
  btnVolDown.addEventListener('click', () => {
-    contractAdapter.applyMutation('mix.master', Math.max(0, audioManager.getMasterVolume() - 0.05), 'ui');
+    contractAdapter?.applyMutation('mix.master', Math.max(0, audioManager.getMasterVolume() - 0.05), 'ui');
  });
  btnVolUp.addEventListener('click', () => {
-    contractAdapter.applyMutation('mix.master', Math.min(1, audioManager.getMasterVolume() + 0.05), 'ui');
+    contractAdapter?.applyMutation('mix.master', Math.min(1, audioManager.getMasterVolume() + 0.05), 'ui');
  });

  volStepButtons.forEach(btn => {
    btn.addEventListener('click', () => {
      const stepVal = parseFloat(btn.getAttribute('data-vol'));
-      contractAdapter.applyMutation('mix.master', stepVal, 'ui');
+      contractAdapter?.applyMutation('mix.master', stepVal, 'ui');
    });
  });

  // 7. Channel Synthesizer Sliders
  sliderHullVol.addEventListener('input', (e) => {
-    contractAdapter.applyMutation('mix.hull.level', parseFloat(e.target.value), 'ui');
+    contractAdapter?.applyMutation('mix.hull.level', parseFloat(e.target.value), 'ui');
  });
  sliderHullFreq.addEventListener('input', (e) => {
-    contractAdapter.applyMutation('mix.hull.frequency', parseFloat(e.target.value), 'ui');
+    contractAdapter?.applyMutation('mix.hull.frequency', parseFloat(e.target.value), 'ui');
  });
  sliderHullCutoff.addEventListener('input', (e) => {
-    contractAdapter.applyMutation('mix.hull.cutoff', parseFloat(e.target.value), 'ui');
+    contractAdapter?.applyMutation('mix.hull.cutoff', parseFloat(e.target.value), 'ui');
  });

  sliderWarpVol.addEventListener('input', (e) => {
-    contractAdapter.applyMutation('mix.drive.level', parseFloat(e.target.value), 'ui');
+    contractAdapter?.applyMutation('mix.drive.level', parseFloat(e.target.value), 'ui');
  });
  sliderWarpBpm.addEventListener('input', (e) => {
-    contractAdapter.applyMutation('mix.drive.pulse-rate', parseInt(e.target.value), 'ui');
+    contractAdapter?.applyMutation('mix.drive.pulse-rate', parseInt(e.target.value), 'ui');
  });
  sliderWarpCarrier.addEventListener('input', (e) => {
-    contractAdapter.applyMutation('mix.drive.carrier', parseFloat(e.target.value), 'ui');
+    contractAdapter?.applyMutation('mix.drive.carrier', parseFloat(e.target.value), 'ui');
  });

  sliderAirVol.addEventListener('input', (e) => {
-    contractAdapter.applyMutation('mix.environment.level', parseFloat(e.target.value), 'ui');
+    contractAdapter?.applyMutation('mix.environment.level', parseFloat(e.target.value), 'ui');
  });
  sliderAirCutoff.addEventListener('input', (e) => {
-    contractAdapter.applyMutation('mix.environment.cutoff', parseFloat(e.target.value), 'ui');
+    contractAdapter?.applyMutation('mix.environment.cutoff', parseFloat(e.target.value), 'ui');
  });

  sliderTelemetryVol.addEventListener('input', (e) => {
-    contractAdapter.applyMutation('mix.telemetry.level', parseFloat(e.target.value), 'ui');
+    contractAdapter?.applyMutation('mix.telemetry.level', parseFloat(e.target.value), 'ui');
  });
  sliderTelemetryDensity.addEventListener('input', (e) => {
-    contractAdapter.applyMutation('mix.telemetry.density', parseFloat(e.target.value), 'ui');
+    contractAdapter?.applyMutation('mix.telemetry.density', parseFloat(e.target.value), 'ui');
  });

  // 8. Universe Event Handlers
@@ -872,7 +1013,7 @@ document.addEventListener('DOMContentLoaded', () => {
      case 'warp':
      case 'quantum':
        alerts.synthesizeWarpJump();
-        visualizer.spawnWarpPulses();
+        visualizer?.spawnWarpPulses();
        break;
      case 'alert-red':
      case 'action-stations':
@@ -902,11 +1043,11 @@ document.addEventListener('DOMContentLoaded', () => {
        break;
      case 'demat':
        whataverseAudio.synthesizeDematCycle(4);
-        visualizer.spawnWarpPulses();
+        visualizer?.spawnWarpPulses();
        break;
      case 'vortex':
        whataverseAudio.synthesizeDematCycle(1);
-        visualizer.spawnWarpPulses();
+        visualizer?.spawnWarpPulses();
        break;
      case 'cloister':
        if (whataverseAudio.activeCloister) {
@@ -923,7 +1064,7 @@ document.addEventListener('DOMContentLoaded', () => {
      case 'epstein':
      case 'subdrive':
        expandedAudio.synthesizeEpsteinBurn();
-        visualizer.spawnWarpPulses();
+        visualizer?.spawnWarpPulses();
        break;
      case 'purge':
      case 'decompress':
@@ -936,11 +1077,11 @@ document.addEventListener('DOMContentLoaded', () => {
      case 'starburst':
      case 'biodefense':
        expandedAudio.synthesizeStarburst();
-        visualizer.spawnWarpPulses();
+        visualizer?.spawnWarpPulses();
        break;
      case 'neural':
        expandedAudio.synthesizeNeuralBondSwell();
-        visualizer.spawnWarpPulses();
+        visualizer?.spawnWarpPulses();
        break;
      case 'centrifuge':
      case 'astrogator':
@@ -951,7 +1092,7 @@ document.addEventListener('DOMContentLoaded', () => {
        break;
      case 'ftl-jump':
        expandedAudio.synthesizeFtlJump();
-        visualizer.spawnWarpPulses();
+        visualizer?.spawnWarpPulses();
        break;
      case 'flak':
        expandedAudio.synthesizeFlakBarrageBurst();
@@ -960,29 +1101,29 @@ document.addEventListener('DOMContentLoaded', () => {
      case 'gravity':
      case 'rotation':
        expandedAudio.synthesizeSingularityEngage();
-        visualizer.spawnWarpPulses();
+        visualizer?.spawnWarpPulses();
        break;
      case 'solar':
        expandedAudio.synthesizeSolarRoar();
-        visualizer.spawnWarpPulses();
+        visualizer?.spawnWarpPulses();
        break;
      case 'afterburner':
        expandedAudio.synthesizeAfterburner();
-        visualizer.spawnWarpPulses();
+        visualizer?.spawnWarpPulses();
        break;
      case 'ludicrous':
        expandedAudio.synthesizeLudicrousSpeed();
-        visualizer.spawnWarpPulses();
+        visualizer?.spawnWarpPulses();
        break;
      case 'improbability':
        expandedAudio.synthesizeImprobabilityFlip();
-        visualizer.spawnWarpPulses();
+        visualizer?.spawnWarpPulses();
        break;
      default:
        telemetry.synthesizeLCARDSingleChirp();
        break;
    }
-    generativeExperience.describeExistingEvent(type);
+    generativeExperience?.describeExistingEvent(type);
  }

  function handleSoundboardTrigger(id) {
@@ -2675,8 +2816,22 @@ document.addEventListener('DOMContentLoaded', () => {
    return spawnObservationTransient(obsExpandingRing(obsInt(450,1150),obsInt(250,650),obsPick(['#06b6d4','#f43f5e','#fbbf24']),obsInt(45,100)),3500);
  }

+  // Step 6.7B: an "audience" is the console's own overlay OR at least one
+  // attached Observation surface. Scheduling/deciding activity uses this;
+  // *local rendering* still gates on observationActive alone (report SS6's
+  // audience-scheduler correction -- without it, an audience watching only
+  // the surface would see a static scene forever).
+  const observationAudienceActive = () => observationActive || !!(surfaceOwner && surfaceOwner.attachedCount() > 0);
+
  function triggerObservationActivity(source = 'ambient') {
-    if (!observationActive || observationActivity <= 0.001) return;
+    if (!observationAudienceActive() || observationActivity <= 0.001) return;
+    // The authority decides; attached surfaces render the same decision
+    // rather than independently rolling their own random event (report SS6,
+    // "Transient activity events are mirrored, not regenerated"). Exact
+    // visual parameters (which contact, which ring) are NOT byte-identical
+    // across documents -- see the accepted-limitations note in README.md /
+    // agents.md; only the "an event happens now" decision is synchronized.
+    if (isConsoleMode && surfaceOwner) surfaceOwner.broadcastPresentation('obs-activity', { source });

    // Telemetry is a synchronization pulse, but the slider controls whether
    // that pulse becomes visible. At maximum every telemetry pulse produces
@@ -2713,7 +2868,12 @@ document.addEventListener('DOMContentLoaded', () => {
      clearTimeout(observationAmbientTimer);
      observationAmbientTimer = null;
    }
-    if (!observationActive || observationActivity <= .01) return;
+    // The Observation surface never runs its own scheduler -- it only
+    // renders 'obs-activity' decisions relayed from the authority. Without
+    // this guard two documents would each roll independent random timers,
+    // violating "no duplicate random event generation" (report SS6/R3).
+    if (!isConsoleMode) return;
+    if (!observationAudienceActive() || observationActivity <= .01) return;

    // Quiet = occasional subtle life. Active = a busy generative display.
    const slow = 12500;
@@ -2798,7 +2958,7 @@ document.addEventListener('DOMContentLoaded', () => {
  updateObservationHudMode();

  sliderObservationActivity.addEventListener('input', () => {
-    contractAdapter.applyMutation('view.activity', Number(sliderObservationActivity.value) / 100, 'ui');
+    contractAdapter?.applyMutation('view.activity', Number(sliderObservationActivity.value) / 100, 'ui');
  });

  window.addEventListener('scifi-telemetry-activity', (event) => {
@@ -4419,6 +4579,48 @@ document.addEventListener('DOMContentLoaded', () => {
    }
  }

+  // Step 6.7B: applies one mirrored contract-state value on the
+  // Observation surface. Reuses the existing local setters/functions
+  // directly -- never contractAdapter.applyMutation (there is none here) --
+  // so this is local *rendering*, not a second computation of authority.
+  // Targets the renderer doesn't care about (mix.*, fnc.*, transport.muted,
+  // speech.*) are intentionally ignored.
+  function applyPresentationState(target, value) {
+    switch (target) {
+      case 'universe.selected':
+        if (value && value !== activeUniverseId) setUniverse(value);
+        break;
+      case 'preset.selected':
+        if (value && value !== activePresetId) selectPreset(value);
+        break;
+      case 'view.viewport-frame':
+        if (observationEngine) observationEngine.setViewport(!!value);
+        break;
+      case 'view.pillars':
+        if (observationEngine) observationEngine.setPillars(!!value);
+        break;
+      case 'view.warp-flight': {
+        if (!observationEngine) break;
+        const isWarp = observationEngine.flightMode === 'warp';
+        if (!!value !== isWarp) observationEngine.toggleWarpFlight();
+        break;
+      }
+      case 'alert.active':
+        if (typeof setAlertActiveDirect === 'function') setAlertActiveDirect(value);
+        break;
+      case 'view.activity':
+        setObservationActivity(Number(value) * 100);
+        break;
+      case 'transport.playing':
+        // Cosmetic only (the "PROCEDURAL AUDIO LINK" status line) -- never
+        // engages audio on the surface.
+        isPlaying = !!value;
+        break;
+      default:
+        break; // view.observation, mix.*, fnc.*, speech.*, transport.muted: not rendered here.
+    }
+  }
+
  function refreshObservation() {
    const universe = UniverseRegistry[activeUniverseId];
    const preset = universe && universe.presets ? universe.presets[activePresetId] : null;
@@ -4442,18 +4644,29 @@ document.addEventListener('DOMContentLoaded', () => {

  function enterObservation() {
    if (observationActive) return;
-    generativeExperience.prepareExperience().catch(err => console.warn('Generative preload failed', err));
+    // Step 6.7B / R2: the single most important guard in this design.
+    // prepareExperience() lazily loads WebLLM + Kokoro (agents.md's one
+    // documented network/import exception); calling it unconditionally
+    // here would make every opened Observation surface download a
+    // multi-gigabyte model. Console-only.
+    if (isConsoleMode) {
+      generativeExperience.prepareExperience().catch(err => console.warn('Generative preload failed', err));
+    }
    observationActive = true;
    observationOverlay.classList.add('active');
    observationOverlay.setAttribute('aria-hidden', 'false');
    refreshObservation();
    resetObservationHudFade();
    resetObservationReturnFade();
-    scheduleObservationAmbientActivity();
+    if (isConsoleMode) {
+      // The Observation surface never runs its own scheduler -- it renders
+      // activity decisions broadcast by the authority (report SS6).
+      scheduleObservationAmbientActivity();

-    // Give the display an immediate but restrained sign of life.
-    if (observationActivity > .08) {
-      window.setTimeout(() => triggerObservationActivity('ambient'), 700);
+      // Give the display an immediate but restrained sign of life.
+      if (observationActivity > .08) {
+        window.setTimeout(() => triggerObservationActivity('ambient'), 700);
+      }
    }
  }

@@ -4502,7 +4715,7 @@ document.addEventListener('DOMContentLoaded', () => {

  btnObservation.addEventListener('click', (e) => {
    e.stopPropagation();
-    contractAdapter.applyMutation('view.observation', !observationActive, 'ui');
+    contractAdapter?.applyMutation('view.observation', !observationActive, 'ui');
  });

  // Click background to exit, but ignore clicks on the control dock or its buttons
@@ -4510,7 +4723,7 @@ document.addEventListener('DOMContentLoaded', () => {
    if (e.target.closest('#observation-control-dock')) return;
    e.preventDefault();
    e.stopPropagation();
-    contractAdapter.applyMutation('view.observation', false, 'ui');
+    contractAdapter?.applyMutation('view.observation', false, 'ui');
  });

  const observationReturnPill = document.getElementById('observation-return-pill');
@@ -4518,19 +4731,21 @@ document.addEventListener('DOMContentLoaded', () => {
    observationReturnPill.addEventListener('click', (e) => {
      e.preventDefault();
      e.stopPropagation();
-      contractAdapter.applyMutation('view.observation', false, 'ui');
+      contractAdapter?.applyMutation('view.observation', false, 'ui');
    });
  }

-  // 10. Keyboard Shortcuts
+  // 10. Keyboard Shortcuts. Step 6.7B: console-only -- a keystroke on the
+  // Observation surface must not mutate state (report SS7).
+  if (isConsoleMode) {
  window.addEventListener('keydown', (e) => {
    if (e.target.tagName === 'INPUT' || e.target.tagName === 'SELECT') return;

    if (e.code === 'Space') {
      e.preventDefault();
-      contractAdapter.applyMutation('transport.playing', !isPlaying, 'hotkey');
+      contractAdapter?.applyMutation('transport.playing', !isPlaying, 'hotkey');
    } else if (e.code === 'KeyM') {
-      contractAdapter.applyMutation('transport.muted', !audioManager.isMuted, 'hotkey');
+      contractAdapter?.applyMutation('transport.muted', !audioManager.isMuted, 'hotkey');
    } else if (e.code === 'KeyW') {
      if (observationActive && observationEngine) {
        observationEngine.toggleWarpFlight();
@@ -4541,7 +4756,7 @@ document.addEventListener('DOMContentLoaded', () => {
      if (primaryEvent) invokeConsoleEvent(primaryEvent, primaryActionBtn, 'hotkey');
    } else if (e.code === 'KeyF') {
      if (observationActive && observationEngine) {
-        contractAdapter.applyMutation('view.viewport-frame', !observationEngine.showViewport, 'hotkey');
+        contractAdapter?.applyMutation('view.viewport-frame', !observationEngine.showViewport, 'hotkey');
        return;
      }
    } else if (e.code === 'KeyP') {
@@ -4552,7 +4767,7 @@ document.addEventListener('DOMContentLoaded', () => {
    } else if (e.code === 'KeyR') {
      if (observationActive && observationEngine) {
        const nextAlert = alerts.activeAlert === 'red' ? 'none' : 'red';
-        contractAdapter.applyMutation('alert.active', nextAlert, 'hotkey');
+        contractAdapter?.applyMutation('alert.active', nextAlert, 'hotkey');
        return;
      }
      const firstAlertBtn = universeEventsContainer.children[1] || universeEventsContainer.children[0];
@@ -4561,23 +4776,24 @@ document.addEventListener('DOMContentLoaded', () => {
      if (alertEvent) invokeConsoleEvent(alertEvent, firstAlertBtn, 'hotkey');
    } else if (e.code === 'ArrowUp' || e.code === 'Equal' || e.code === 'NumpadAdd') {
      e.preventDefault();
-      contractAdapter.applyMutation('mix.master', Math.min(1, audioManager.getMasterVolume() + 0.05), 'hotkey');
+      contractAdapter?.applyMutation('mix.master', Math.min(1, audioManager.getMasterVolume() + 0.05), 'hotkey');
    } else if (e.code === 'ArrowDown' || e.code === 'Minus' || e.code === 'NumpadSubtract') {
      e.preventDefault();
-      contractAdapter.applyMutation('mix.master', Math.max(0, audioManager.getMasterVolume() - 0.05), 'hotkey');
+      contractAdapter?.applyMutation('mix.master', Math.max(0, audioManager.getMasterVolume() - 0.05), 'hotkey');
    } else if (e.code >= 'Digit1' && e.code <= 'Digit9') {
      const num = parseInt(e.code.replace('Digit', ''));
-      contractAdapter.applyMutation('mix.master', num * 0.1, 'hotkey');
+      contractAdapter?.applyMutation('mix.master', num * 0.1, 'hotkey');
    } else if (e.code === 'Digit0') {
-      contractAdapter.applyMutation('mix.master', 1.0, 'hotkey');
+      contractAdapter?.applyMutation('mix.master', 1.0, 'hotkey');
    } else if (e.code === 'Escape') {
      if (observationActive) {
-        contractAdapter.applyMutation('view.observation', false, 'hotkey');
+        contractAdapter?.applyMutation('view.observation', false, 'hotkey');
        return;
      }
-      contractAdapter.applyMutation('alert.active', 'none', 'hotkey');
+      contractAdapter?.applyMutation('alert.active', 'none', 'hotkey');
    }
  });
+  } // end isConsoleMode (keyboard shortcuts)

  // --- Implementation of Absolute Setters and Contract Helpers ---
  setMasterVolumeDirect = function (val, isMuted = false) {
@@ -4688,6 +4904,8 @@ document.addEventListener('DOMContentLoaded', () => {
      'fnc.level': fncSystem ? fncSystem.level : 0.5,
      'view.observation': observationActive,
      'view.viewport-frame': observationEngine ? observationEngine.showViewport : true,
+      'view.pillars': observationEngine ? observationEngine.showPillars : false,
+      'view.warp-flight': observationEngine ? observationEngine.flightMode === 'warp' : false,
      'view.activity': observationActivity,
      'alert.active': alertStatus,
      'universe.selected': activeUniverseId,
@@ -4699,5 +4917,5 @@ document.addEventListener('DOMContentLoaded', () => {
  initUniverseDropdown();
  setUniverse('starfleet');
  updateMasterVolumeUI(0.75, false);
-  visualizer.init('spectrum-canvas', 'warp-core-canvas');
+  visualizer?.init('spectrum-canvas', 'warp-core-canvas');
 });
@@ -1,5 +1,5 @@
 /**
- * XZBT Contract Adapter — Specification v5.2
+ * XZBT Contract Adapter — Specification v5.3
 *
 * Implements the normalized contract interface for SciFi-XZBT:
 * - Canonical external target catalog & descriptors
@@ -15,10 +15,10 @@
  class XZBTContractAdapter {
    constructor(options = {}) {
      this.product = options.product || 'SciFi-XZBT';
-      this.version = options.version || '5.2.0';
+      this.version = options.version || '5.3.0';
      this.build = options.build || 'production';
      this.contractMajor = 5;
-      this.contractMinor = 2;
+      this.contractMinor = 3;

      this.sessionId = null;
      this.sessionActive = false;
@@ -28,6 +28,17 @@
      this.operationQueue = Promise.resolve();
      this.eventSink = null;

+      // Surface catalog (Contract 5.3 §31.2/§31.3). Advertised in describe()
+      // only when non-empty, so absence stays §31.3 form 1 ("absent").
+      this.surfaces = Array.isArray(options.surfaces) ? options.surfaces : null;
+      this.instanceId = options.instanceId || null;
+
+      // Session-independent local-change hooks (Step 6.7B). Unlike
+      // _emitEvent, these fire regardless of sessionActive so an
+      // exhibit-internal surface mirror keeps working with no NGN attached.
+      this.onLocalChange = typeof options.onLocalChange === 'function' ? options.onLocalChange : null;
+      this.onLocalAction = typeof options.onLocalAction === 'function' ? options.onLocalAction : null;
+
      // Transport hooks
      this.onMessage = options.onMessage || (() => {});
      this.hostOrigin = options.hostOrigin || null; // optional origin filter
@@ -355,6 +366,31 @@
        requires: ['observation']
      });

+      reg({
+        id: 'view.pillars',
+        legacyId: 'observation-pillars',
+        label: 'Window Pillars / Mullions',
+        kind: 'state',
+        valueType: 'boolean',
+        readable: true,
+        writable: true,
+        restorable: true,
+        category: 'observation',
+        requires: ['observation']
+      });
+
+      reg({
+        id: 'view.warp-flight',
+        label: 'Warp Flight Mode',
+        kind: 'state',
+        valueType: 'boolean',
+        readable: true,
+        writable: true,
+        restorable: true,
+        category: 'observation',
+        requires: ['observation']
+      });
+
      reg({
        id: 'alert.active',
        label: 'Active Tactical Alert Status',
@@ -416,9 +452,9 @@
        restorable: false,
        category: 'speech',
        requires: ['speech'],
-        args: {
-          text: { type: 'string', required: true, maxLength: 2000 }
-        }
+        arguments: [
+          { name: 'text', type: 'string', required: true, maxLength: 2000 }
+        ]
      });

      reg({
@@ -442,9 +478,9 @@
        restorable: false,
        category: 'display',
        requires: ['display-text'],
-        args: {
-          text: { type: 'string', required: true, maxLength: 512 }
-        }
+        arguments: [
+          { name: 'text', type: 'string', required: true, maxLength: 512 }
+        ]
      });

      // --- 4. Canonical Universe Event Impulses ---
@@ -555,7 +591,7 @@
          return;
        }
        // Ignore non-XZBT messages
-        if (!e.data || typeof e.data !== 'object' || e.data.xzbt !== '5.2') {
+        if (!e.data || typeof e.data !== 'object' || typeof e.data.xzbt !== 'string') {
          return;
        }
        if (e.data.sequence || e.data.type === 'error' || /\.result$/.test(e.data.type)) return;
@@ -616,6 +652,15 @@
          stateRevision: this.stateRevision, target: target.id, value: after[target.id]
        }, correlationId, source);
      }
+      // Session-independent mirror feed (Step 6.7B). _emitEvent above is
+      // gated on sessionActive and therefore silent with no NGN attached;
+      // onLocalChange is not, so an exhibit-internal surface mirror keeps
+      // working standalone. Fires for every changed target, same as above.
+      if (this.onLocalChange) {
+        for (const target of changes) {
+          this.onLocalChange(target.id, after[target.id], this.stateRevision);
+        }
+      }
      return true;
    }

@@ -755,11 +800,13 @@

      // Validate args schema & text length limits if defined
      const sanitizedArgs = (args && typeof args === 'object' && !Array.isArray(args)) ? { ...args } : {};
-      if (Object.keys(sanitizedArgs).some(key => !target.args || !target.args[key])) {
+      const argumentSpecs = target.arguments || [];
+      if (Object.keys(sanitizedArgs).some(key => !argumentSpecs.some(spec => spec.name === key))) {
        return { ok: false, code: 'INVALID_VALUE', message: 'Unexpected argument key' };
      }
-      if (target.args) {
-        for (const [argKey, argSpec] of Object.entries(target.args)) {
+      if (argumentSpecs.length) {
+        for (const argSpec of argumentSpecs) {
+          const argKey = argSpec.name;
          if (argSpec.required && (sanitizedArgs[argKey] === undefined || sanitizedArgs[argKey] === null)) {
            return { ok: false, code: 'INVALID_VALUE', message: `Missing required argument '${argKey}'` };
          }
@@ -823,6 +870,11 @@
        args: sanitizedArgs
      }, correlationId, source);

+      // Session-independent mirror feed (Step 6.7B); see _commitChanges.
+      if (this.onLocalAction) {
+        this.onLocalAction(canonicalId, sanitizedArgs);
+      }
+
      return { ok: true };
    }

@@ -836,7 +888,7 @@

    // Public API: Protocol Description
    describe() {
-      return {
+      const description = {
        exhibit: {
          product: this.product,
          version: this.version,
@@ -851,6 +903,10 @@
        capabilities: Array.from(this.capabilities.values()),
        targets: Array.from(this.targets.values())
      };
+      if (this.surfaces && this.surfaces.length) {
+        description.surfaces = this.surfaces;
+      }
+      return description;
    }

    // Update Capability state and emit capability.changed
@@ -204,7 +204,12 @@ class ObservationEngine {
    if (this.btnWarp) {
      this.btnWarp.addEventListener('click', (e) => {
        e.stopPropagation();
-        this.toggleWarpFlight();
+        // Step 6.7B: route through the canonical view.warp-flight target,
+        // like btnFrame's view.viewport-frame, instead of mutating engine
+        // state directly -- this is what lets the Observation surface and
+        // the console converge through the one mutation chokepoint.
+        if (this.onMutation) this.onMutation('view.warp-flight', this.flightMode !== 'warp');
+        else this.toggleWarpFlight();
      });
    }

@@ -219,7 +224,9 @@ class ObservationEngine {
    if (this.btnPillars) {
      this.btnPillars.addEventListener('click', (e) => {
        e.stopPropagation();
-        this.togglePillars();
+        // Step 6.7B: route through the canonical view.pillars target.
+        if (this.onMutation) this.onMutation('view.pillars', !this.showPillars);
+        else this.togglePillars();
      });
    }

@@ -0,0 +1,254 @@
+/**
+ * XZBT Surface Bus — SciFi-XZBT (Step 6.7B)
+ *
+ * Exhibit-internal state mirror between the authoritative console document
+ * and the non-authoritative Observation surface document. Adapted from
+ * Museum Gallery's proven `surface-bus.js` shape (Steps 6.3-6.6), with one
+ * deliberate improvement: the BroadcastChannel name is scoped to a single
+ * console instance id (XZBTSurfaceMode.channelName), so two console tabs on
+ * one origin cannot cross-talk.
+ *
+ * This carries NO XZBT Exhibit Contract envelope — no `xzbt` field, no
+ * `sessionId` — and is never observed by an NGN host (Contract 5.3 §31.7's
+ * explicit allowance for exhibit-internal transports). Message shapes:
+ *
+ *   surface -> owner : { type:'attach',  requestId, participantId }
+ *   owner -> surface : { type:'attach.snapshot', inReplyTo, values,
+ *                        stateRevision, registryRevision,
+ *                        presentation:{ tickerText } }
+ *   owner -> all     : { type:'state',   target, value, stateRevision }
+ *   owner -> all     : { type:'action',  target, args }
+ *   owner -> all     : { type:'presentation', kind:'ticker'|'obs-activity', ... }
+ *   surface -> owner : { type:'mutate',  kind:'set'|'invoke', target, value|args }
+ *   surface -> owner : { type:'detach',  participantId }
+ */
+(function (root) {
+  'use strict';
+
+  function randomId() {
+    return 'req-' + Math.random().toString(16).slice(2) + Date.now().toString(16);
+  }
+
+  /**
+   * Owner side. Call once, in the console (authoritative) document, after
+   * the XZBTContractAdapter has been constructed.
+   *
+   * @param {object} adapter an XZBTContractAdapter instance
+   * @param {object} options
+   * @param {string} options.channelName instance-scoped channel name
+   * @param {function} [options.onParticipantsChanged] (attachedCount)
+   */
+  function createOwner(adapter, options) {
+    options = options || {};
+    if (!options.channelName) {
+      throw new Error('surface-bus: createOwner requires options.channelName');
+    }
+    var channel = new BroadcastChannel(options.channelName);
+    var lastPresentation = { tickerText: '' };
+
+    // Set-based participant bookkeeping (not a counter): a duplicate/late
+    // attach or detach can never ratchet the count (Museum's lesson).
+    var participants = new Set();
+    var closed = false;
+
+    function notifyParticipantsChanged() {
+      if (typeof options.onParticipantsChanged === 'function') {
+        options.onParticipantsChanged(participants.size);
+      }
+    }
+
+    function currentValues() {
+      var state = adapter.getContractState();
+      var values = {};
+      adapter.targets.forEach(function (target, id) {
+        if (target.readable && target.kind !== 'impulse') {
+          values[id] = state[id];
+        }
+      });
+      return values;
+    }
+
+    channel.onmessage = function (ev) {
+      var msg = ev.data;
+      if (!msg || typeof msg !== 'object') return;
+
+      if (msg.type === 'attach') {
+        if (typeof msg.participantId === 'string') {
+          participants.add(msg.participantId);
+        }
+        channel.postMessage({
+          type: 'attach.snapshot',
+          inReplyTo: msg.requestId,
+          values: currentValues(),
+          stateRevision: adapter.stateRevision,
+          registryRevision: adapter.registryRevision,
+          presentation: lastPresentation
+        });
+        notifyParticipantsChanged();
+        return;
+      }
+
+      if (msg.type === 'mutate') {
+        // Every surface-originated interaction goes through exactly the
+        // same applyMutation/invokeAction chokepoint a contract set/invoke
+        // from NGN would use. Source is always 'ui'.
+        if (msg.kind === 'set' && typeof msg.target === 'string') {
+          adapter.applyMutation(msg.target, msg.value, 'ui');
+        } else if (msg.kind === 'invoke' && typeof msg.target === 'string') {
+          adapter.invokeAction(msg.target, msg.args || {}, 'ui');
+        }
+        return;
+      }
+
+      if (msg.type === 'detach') {
+        if (typeof msg.participantId === 'string' && participants.delete(msg.participantId)) {
+          notifyParticipantsChanged();
+        }
+      }
+    };
+
+    return {
+      channel: channel,
+      attachedCount: function () { return participants.size; },
+      /** Broadcast one changed target (fed from adapter.onLocalChange). */
+      broadcastState: function (target, value, stateRevision) {
+        if (closed) return;
+        channel.postMessage({ type: 'state', target: target, value: value, stateRevision: stateRevision });
+      },
+      /** Broadcast an executed impulse (fed from adapter.onLocalAction). */
+      broadcastAction: function (target, args) {
+        if (closed) return;
+        channel.postMessage({ type: 'action', target: target, args: args || {} });
+      },
+      /** Broadcast a transient presentation-only extra (ticker text, an
+       * ambient-activity decision). Not contract state. */
+      broadcastPresentation: function (kind, payload) {
+        if (closed) return;
+        var msg = Object.assign({ type: 'presentation', kind: kind }, payload || {});
+        if (kind === 'ticker' && payload && typeof payload.tickerText === 'string') {
+          lastPresentation = { tickerText: payload.tickerText };
+        }
+        channel.postMessage(msg);
+      },
+      detach: function () {
+        if (closed) return;
+        closed = true;
+        channel.close();
+      }
+    };
+  }
+
+  /**
+   * Surface side. Call from the Observation surface document. Requests
+   * attachment and waits `timeoutMs` for a reply; if no owner document is
+   * open on the same channel, `onTimeout` fires and the surface must
+   * degrade to a waiting state rather than inventing its own authority.
+   *
+   * @param {object} options
+   * @param {string} options.channelName instance-scoped channel name
+   * @param {number} [options.timeoutMs]
+   * @param {function} [options.onSnapshot] (values, stateRevision, registryRevision, presentation)
+   * @param {function} [options.onChange] (target, value, stateRevision)
+   * @param {function} [options.onAction] (target, args)
+   * @param {function} [options.onPresentation] (kind, payload)
+   * @param {function} [options.onTimeout]
+   */
+  function attach(options) {
+    options = options || {};
+    if (!options.channelName) {
+      throw new Error('surface-bus: attach requires options.channelName');
+    }
+    var channel = new BroadcastChannel(options.channelName);
+    var requestId = randomId();
+    // A fresh participantId per attach() call. A reload is a brand-new
+    // attach() and therefore a brand-new id, which is what lets the
+    // owner's Set-based bookkeeping retire the old identity cleanly.
+    var participantId = randomId();
+    var attachedFlag = false;
+    var detachedFlag = false;
+
+    var timer = setTimeout(function () {
+      if (attachedFlag) return;
+      if (typeof options.onTimeout === 'function') options.onTimeout();
+    }, options.timeoutMs || 1500);
+
+    channel.onmessage = function (ev) {
+      var msg = ev.data;
+      if (!msg || typeof msg !== 'object') return;
+
+      if (msg.type === 'attach.snapshot' && msg.inReplyTo === requestId && !attachedFlag) {
+        attachedFlag = true;
+        clearTimeout(timer);
+        if (typeof options.onSnapshot === 'function') {
+          options.onSnapshot(msg.values, msg.stateRevision, msg.registryRevision, msg.presentation);
+        }
+        return;
+      }
+
+      if (!attachedFlag) return;
+
+      if (msg.type === 'state') {
+        if (typeof options.onChange === 'function') {
+          options.onChange(msg.target, msg.value, msg.stateRevision);
+        }
+        return;
+      }
+
+      if (msg.type === 'action') {
+        if (typeof options.onAction === 'function') {
+          options.onAction(msg.target, msg.args);
+        }
+        return;
+      }
+
+      if (msg.type === 'presentation') {
+        if (typeof options.onPresentation === 'function') {
+          options.onPresentation(msg.kind, msg);
+        }
+      }
+    };
+
+    channel.postMessage({ type: 'attach', requestId: requestId, participantId: participantId });
+
+    function detach() {
+      // Idempotent: local-surfaces.js's pre-removal dispose call and this
+      // document's own beforeunload handler can both fire for the same
+      // attachment. Only the first actually posts; every call tears down
+      // the timer/channel so repeated calls are always safe.
+      if (attachedFlag && !detachedFlag) {
+        detachedFlag = true;
+        channel.postMessage({ type: 'detach', participantId: participantId });
+      }
+      clearTimeout(timer);
+      channel.close();
+    }
+
+    return {
+      channel: channel,
+      isAttached: function () { return attachedFlag; },
+      /** Route a native surface interaction through the owner's canonical
+       * mutation path. No-op (returns false) if not yet attached. */
+      mutate: function (kind, target, valueOrArgs) {
+        if (!attachedFlag) return false;
+        var payload = { type: 'mutate', kind: kind, target: target };
+        if (kind === 'set') payload.value = valueOrArgs;
+        else payload.args = valueOrArgs || {};
+        channel.postMessage(payload);
+        return true;
+      },
+      detach: detach
+    };
+  }
+
+  var XZBTSurfaceBus = {
+    createOwner: createOwner,
+    attach: attach
+  };
+
+  if (typeof module !== 'undefined' && module.exports) {
+    module.exports = XZBTSurfaceBus;
+  }
+  if (root) {
+    root.XZBTSurfaceBus = XZBTSurfaceBus;
+  }
+})(typeof window !== 'undefined' ? window : (typeof globalThis !== 'undefined' ? globalThis : this));
@@ -0,0 +1,108 @@
+/**
+ * XZBT Surface Mode — SciFi-XZBT (Step 6.7B)
+ *
+ * Pure, testable seam for resolving which boot mode this document load is in
+ * (Contract 5.3 §31.4 query-string surface form) and for describing the
+ * exhibit's two-entry surface catalog. No DOM access, no imports, no
+ * side effects — safe to load and exercise under Node's `vm` module.
+ *
+ * Two surfaces only:
+ *   - surface.console      the full operator console (index.html, primary)
+ *   - surface.observation  the same document, rendering only the
+ *                          Observation viewscreen, addressed by
+ *                          ?surface=observation&xi=<instanceId>
+ */
+(function (root) {
+  'use strict';
+
+  var CHANNEL_PREFIX = 'xzbt-scifi-surface-v1:';
+
+  /**
+   * Resolve the boot mode + instance id for a location-like object.
+   * @param {object} locationLike anything with a `.search` (or `.href`)
+   *   string, e.g. `window.location`.
+   * @returns {{mode: 'console'|'observation', instanceId: string|null}}
+   */
+  function resolve(locationLike) {
+    var search = '';
+    if (locationLike && typeof locationLike.search === 'string') {
+      search = locationLike.search;
+    } else if (locationLike && typeof locationLike.href === 'string') {
+      var qIdx = locationLike.href.indexOf('?');
+      search = qIdx >= 0 ? locationLike.href.slice(qIdx) : '';
+    }
+
+    var params;
+    try {
+      params = new URLSearchParams(search);
+    } catch (err) {
+      params = null;
+    }
+
+    var surfaceParam = params ? params.get('surface') : null;
+    var instanceId = params ? params.get('xi') : null;
+
+    if (surfaceParam === 'observation') {
+      return { mode: 'observation', instanceId: instanceId || null };
+    }
+
+    // Unknown/absent `?surface=` values resolve to console. `xi` is
+    // meaningless in console mode.
+    return { mode: 'console', instanceId: null };
+  }
+
+  /** Mint a fresh per-document-load instance id. */
+  function newInstanceId() {
+    return 'xi-' + Math.random().toString(16).slice(2) + Date.now().toString(16);
+  }
+
+  /**
+   * The exhibit's two-entry surface catalog (Contract 5.3 §31.2/§31.3).
+   * @param {string} instanceId the live console instance id.
+   */
+  function SURFACES(instanceId) {
+    return [
+      {
+        id: 'surface.console',
+        label: 'Main Console',
+        kind: 'surface',
+        primary: true,
+        url: 'index.html',
+        role: 'control',
+        category: 'console',
+        description: 'The full SciFi-XZBT operator console.'
+      },
+      {
+        id: 'surface.observation',
+        label: 'Observation',
+        kind: 'surface',
+        primary: false,
+        url: '?surface=observation&xi=' + encodeURIComponent(instanceId),
+        role: 'ambient',
+        category: 'observation',
+        aspectRatio: '16:9',
+        requires: ['observation'],
+        description: 'Full-screen procedural viewscreen mirroring the console.'
+      }
+    ];
+  }
+
+  /** The instance-scoped BroadcastChannel name for a console instance id. */
+  function channelName(instanceId) {
+    return CHANNEL_PREFIX + instanceId;
+  }
+
+  var XZBTSurfaceMode = {
+    resolve: resolve,
+    newInstanceId: newInstanceId,
+    SURFACES: SURFACES,
+    channelName: channelName
+  };
+
+  if (typeof module !== 'undefined' && module.exports) {
+    module.exports = XZBTSurfaceMode;
+  }
+  if (root) {
+    root.XZBTSurfaceMode = XZBTSurfaceMode;
+  }
+})(typeof window !== 'undefined' ? window : (typeof globalThis !== 'undefined' ? globalThis : this));
@@ -1,5 +1,5 @@
 /*
- * XZBT Exhibit Contract 5.2 — generic contract core.
+ * XZBT Exhibit Contract 5.3 — generic contract core.
 *
 * WHY THIS FILE IS GENERIC
 * ------------------------
@@ -26,25 +26,33 @@
  'use strict';

  var CONTRACT_MAJOR = 5;
-  var CONTRACT_MINOR = 2;
-  var XZBT_VERSION = '5.2';
+  var CONTRACT_MINOR = 3;
+  var XZBT_VERSION = '5.3';

  /*
-   * Contract 5.3 presentation-surface support (additive, optional).
+   * Contract 5.3 presentation-surface support.
   *
-   * Every existing exhibit that does not pass `contractMinor`, `xzbtVersion`,
-   * or `surfaces` to ContractCore gets byte-identical behavior to before this
-   * addition: the defaults below equal the pre-5.3 constants exactly, and
-   * `describe()` omits the `surfaces` key entirely unless a SurfaceCatalog
-   * was supplied. This file remains domain-free; it knows the *shape* of
-   * Contract 5.3 Section 31, not any exhibit's surface content.
+   * `surfaces` remains OPTIONAL per-exhibit: an exhibit that does not supply
+   * a SurfaceCatalog simply gets no `surfaces` key in `describe()` at all
+   * (Contract 5.3 §7). This file remains domain-free; it knows the *shape*
+   * of Contract 5.3 Section 31, not any exhibit's surface content.
+   *
+   * `CONTRACT_MINOR`/`XZBT_VERSION` above are this module's defaults, used by
+   * any exhibit that does not pass its own `contractMinor`/`xzbtVersion` to
+   * ContractCore. XZBT-NGN's maintained exhibit set moves forward with the
+   * contract (Contract 5.3 Changelog, §39): there is no standing requirement
+   * to keep a *currently maintained* exhibit frozen on an old minor version
+   * merely because it once shipped against it. An exhibit that has a real,
+   * independently justified reason to stay on an older minor may still pass
+   * an explicit lower `contractMinor`/`xzbtVersion` — nothing here prevents
+   * that — but it is no longer the silent default.
   */

-  /* Contract 5.2 §15. The exhibit assigns source at its own trusted
+  /* Contract §15. The exhibit assigns source at its own trusted
   * boundary; a source supplied by a caller is never trusted. */
  var SOURCES = ['ui', 'midi', 'hotkey', 'host', 'scenario', 'internal', 'system'];

-  /* Contract 5.2 §24. */
+  /* Contract §24. */
  var ERROR_CODES = [
    'UNSUPPORTED_VERSION',
    'INVALID_MESSAGE',
@@ -59,10 +67,10 @@
    'INTERNAL_ERROR'
  ];

-  /* Contract 5.2 §17. */
+  /* Contract §17. */
  var CAPABILITY_STATES = ['unsupported', 'available', 'loading', 'ready', 'busy', 'error'];

-  /* Contract 5.2 §16. The base event set is closed; exhibits do not invent
+  /* Contract §16. The base event set is closed; exhibits do not invent
   * new canonical event types. */
  var EVENT_TYPES = [
    'state.changed',
@@ -746,14 +754,13 @@
    if (!isPlainObject(message)) {
      return this._errorEnvelope(null, null, 'INVALID_MESSAGE', 'Message must be an object.');
    }
-    if (message.xzbt !== this.xzbtVersion) {
-      return this._errorEnvelope(
-        message.requestId || null,
-        message.sessionId || null,
-        'UNSUPPORTED_VERSION',
-        'This exhibit implements contract ' + this.xzbtVersion + '.'
-      );
-    }
+    /* `xzbt` is advisory metadata, not a compatibility gate (Contract §6.5):
+     * a 5.3-aware host must still interoperate with a 5.2 exhibit and vice
+     * versa. Real compatibility is negotiated by handleHello below via
+     * `supportedContractMajors`/`contract.major`/`minor`; rejecting here on
+     * an exact string mismatch pre-empted that negotiation and made it
+     * impossible for a host and exhibit that both implement the contract,
+     * but stamp different advisory xzbt strings, to ever connect. */
    if (typeof message.type !== 'string') {
      return this._errorEnvelope(
        message.requestId || null,
@@ -1,5 +1,5 @@
 /*
- * XZBT Exhibit Contract 5.2 — same-origin postMessage host transport.
+ * XZBT Exhibit Contract 5.3 — same-origin postMessage host transport.
 *
 * This is layer 6 of the Authoring Guide's recommended separation, and it is
 * deliberately the thinnest file in the project. It knows how to move
@@ -61,7 +61,15 @@

    var message = event.data;
    if (!message || typeof message !== 'object') return;
-    if (message.xzbt !== window.XZBTContractCore.VERSION) return;
+    /* `xzbt` is advisory metadata, not a version gate (Contract §6.5): real
+     * compatibility is negotiated by ContractCore.handleRequest/handleHello
+     * via contract major/minor, not by string-matching the caller's
+     * advisory tag against this exhibit's own static module version here.
+     * (This used to compare against window.XZBTContractCore.VERSION, the
+     * shared module's fixed default -- never the per-instance version an
+     * exhibit actually negotiates -- so it silently discarded every
+     * message from any host whose advisory tag didn't happen to equal
+     * that hardcoded default, including well-formed hellos.) */

    /* Source is assigned here, at the trusted receiving boundary. */
    var response = this.core.handleRequest(message, 'host');