docs(devlog): add missing devlog entries for Steps 5, 6.3, and Step 6 completion

.labyricorn/devlog/contents.lr

@@ -2,6 +2,6 @@ _model: devlog
 ---
 schema_version: 1
 ---
-title: Labyricorn Project Template development log
+title: XZBT-NGN Exhibit Engine development log
 ---
-summary: Milestones and development log entries for the Labyricorn project template.
+summary: Milestones and development log entries for the XZBT-NGN Exhibit Engine project.

.labyricorn/devlog/contract-5-3-accepted-baseline/contents.lr

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+_model: devlog-entry
+---
+schema_version: 1
+---
+title: Contract 5.3 Accepted Technical Baseline
+---
+date: 2026-09-15
+---
+author: cgcha
+---
+summary: Established the accepted Contract 5.3 multi-surface technical baseline at f163de2, verified by 154 automated tests, SciFi surface smoke tests, and live browser verification.
+---
+tags: step6, contract-5-3, baseline, scifi-xzbt, multi-surface
+---
+source_commit: f163de264388f1e411cf9e54f26f72a254888afd
+---
+body: |
+  This devlog entry records the formal acceptance and freezing of the Contract 5.3 multi-surface technical baseline at commit 163de264388f1e411cf9e54f26f72a254888afd, marked by the annotated tag contract-5.3-accepted-baseline.
+
+  Following the integration of local presentation panes (Step 6.4) and the adaptation of the SciFi-XZBT Observation surface (Step 6.7), this milestone incorporates two key fixture-level presentation corrections:
+  1. Clearing centered 16:9 overlay geometry when the Observation surface is embedded inside an NGN host pane so that it fills its assigned presentation geometry cleanly.
+  2. Presenting an inert waiting state when an Observation surface is loaded without an active owner attachment, ensuring orphaned surfaces fail closed and never invent secondary authority.
+
+  Verification highlights:
+  - **Automated Suites:** The full automated test suite passes **154 / 154** tests, and the focused SciFi Observation surface smoke suite passes **24 / 24** tests.
+  - **Packaging:** Regenerated standalone single-file builds were verified for complete resource inlining and served-path handshake execution.
+  - **Live Browser Verification:** Passed the eight-point live browser acceptance procedure across pane geometry, target state convergence, clean reload/reopen lifecycle, console-only heavy subsystems (no WebLLM, Kokoro TTS, or AudioContext in surface frames), and orphan fail-closed behavior.

.labyricorn/devlog/step-5-completion/contents.lr

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+_model: devlog-entry
+---
+schema_version: 1
+---
+title: Step 5 Completion: MVP Verification and Reference Exhibits
+---
+date: 2026-09-14
+---
+author: cgcha
+---
+summary: Finalized the Step 5 MVP with 27 automated tests passing, SciFi-XZBT text argument corrections, and browser verification across reference exhibits.
+---
+tags: step5, mvp, verification, reference-exhibits
+---
+source_commit: 961919e017b196104c0c8b6fe4b6881399831186
+---
+body: |
+  This devlog entry records the completion of the XZBT-NGN Step 5 MVP.
+
+  The implementation establishes a single-exhibit host engine for XZBT Exhibit Contract 5.2/5.3 capable of negotiating sessions, discovering descriptor-driven controls, dispatching set and invoke operations, and displaying incoming capabilities, events, revisions, and protocol errors.
+
+  Key achievements:
+  - **Automated Testing:** All 27 automated unit and integration tests pass cleanly.
+  - **Reference Exhibit Alignment:** SciFi-XZBT argument descriptors were corrected, enabling both text line and AI announcement invocations to execute through the generic operator UI.
+  - **Conformant Behavior:** Haunted House was verified to report conformant values, and Museum Gallery demonstrated compliant contract negotiation.
+  - **Documentation:** Step 5 verification and architecture boundaries are recorded in STEP5-MVP-COMPLETION-REPORT.md.

.labyricorn/devlog/step-6-completion/contents.lr

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+_model: devlog-entry
+---
+schema_version: 1
+---
+title: Step 6 Multi-Surface Architecture Completion and Closure
+---
+date: 2026-09-15
+---
+author: cgcha
+---
+summary: Formally closed Step 6 under tag step-6-complete following Step 6.10 completion gate adjudication, with 12 architectural invariants verified and non-blocking follow-up documented.
+---
+tags: step6, completion, architecture, closure
+---
+source_commit: 9dcd3993dbedfea358813e0312e0d5e5098376a7
+---
+body: |
+  This devlog entry marks the formal closure of Step 6 for XZBT-NGN under annotated tag step-6-complete.
+
+  The Step 6.10 completion gate concluded with the formal disposition: **STEP 6 COMPLETE WITH DOCUMENTED NON-BLOCKING FOLLOW-UP**.
+
+  Milestone outcomes and adjudications:
+  - **Step 6.5 Synchronization Proof:** Formally adjudicated as satisfied by existing implementation and later evidence. Multi-surface state synchronization is guaranteed by a single authoritative Exhibit State Core, snapshot and stateRevision transmission on attachment, monotonic event propagation, and routing secondary interactions through owner authority.
+  - **Step 6.8 Multi-Surface Behavior:** Complete and accepted. A single session renegotiation observed once during testing could not be reproduced, had no architectural defect identified, preserved state, recovered cleanly, and remains tracked as an ongoing non-blocking observation.
+  - **Architectural Invariants:** All 12 core architectural invariants were verified, confirming single-owner mutation authority, exhibit-generic host design, non-authoritative surfaces, same-origin security boundaries, and full Contract 5.3 protocol conformance.
+  - **Zero Blocking Items:** No blocking defects or outstanding implementation tasks remain for Step 6. Five non-blocking follow-up items are retained for operational observation.
+
+  The complete closure documentation is published in docs/reference/XZBT-NGN-Step6.10-Closure-Report.md.

.labyricorn/devlog/step-6-surface-discovery/contents.lr

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+_model: devlog-entry
+---
+schema_version: 1
+---
+title: Step 6.3: Generic Contract 5.3 Surface Discovery
+---
+date: 2026-09-14
+---
+author: cgcha
+---
+summary: Implemented normative Contract 5.3 Part 8 presentation-surface discovery, catalog validation, and descriptor-driven UI rendering with 88 automated tests passing.
+---
+tags: step6, contract-5-3, surfaces, discovery
+---
+source_commit: dcae56a4b639697176fbe9638e76df00e2870b32
+---
+body: |
+  This devlog entry marks the completion of Step 6.3, introducing generic presentation-surface discovery under XZBT Exhibit Contract 5.3.
+
+  Contract 5.3 introduces Part 8 presentation surfaces, allowing exhibits to declare supplementary secondary displays (such as ambient screens, observatories, or cast views) alongside their primary interaction console.
+
+  Key additions in this milestone:
+  - **Catalog Validation:** Added alidateSurfaceCatalog() in src/validation.js, implementing Contract 5.3 §§31.2–31.5 normative validation order (evaluating individual descriptors, discarding malformed entries, and enforcing the single primary invariant).
+  - **Host Integration:** src/host.js emits the xzbt: '5.3' advisory envelope on hello, tracks contractMinor, and parses advertised surfaces on initial connection and dynamic
+egistry.changed notifications.
+  - **Generic UI Rendering:** src/ui.js dynamically renders discovered presentation surfaces with metadata badges and opening controls.
+  - **Test Suite:** Added 45 comprehensive automated tests covering all Part 8 malformed surface cases, lifecycle events, and Contract 5.2 backward compatibility, bringing the automated test suite to 88/88 passing tests.