diff --git a/.beads/issues.jsonl b/.beads/issues.jsonl
index 26630a0..6e7153b 100644
--- a/.beads/issues.jsonl
+++ b/.beads/issues.jsonl
@@ -42,6 +42,7 @@
 {"id":"ifcurl-ei8","title":"Fix syncCameraUrl: convert WebGL coords to IFC world space","description":"syncCameraUrl in viewer.py currently records camera.position/direction/up directly from Three.js, which are in WebGL/Three.js coordinate space (Y-up, different scale/orientation than IFC). The ifc:// URL spec expects IFC world coordinates (Z-up, matching BCF viewpoint conventions). Need to find the IFC→Three.js transform that @thatopen/components applies when loading a model, then apply its inverse in syncCameraUrl before serialising the camera params. Repos cloned for reference: ~/src/engine_components and ~/src/engine_fragment.","status":"closed","priority":2,"issue_type":"bug","owner":"bruno@postle.net","created_at":"2026-04-23T05:53:06Z","created_by":"Bruno Postle","updated_at":"2026-04-23T06:14:36Z","closed_at":"2026-04-23T06:14:36Z","close_reason":"Split into atomic tasks: ifcurl-ldk, ifcurl-j2s, ifcurl-cmd","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"id":"ifcurl-i1s","title":"Test Phase 3b web viewer end-to-end","description":"After deploying the footer template (ifcurl-ach), test the full flow: open an .ifc file in Forgejo at localhost:3000, click 'View in 3D', verify the viewer loads the model. CDN versions (@thatopen/components 2.4.0, three 0.160.0, web-ifc 0.0.66) may need adjustment if the API has changed.","status":"closed","priority":2,"issue_type":"task","assignee":"Bruno Postle","owner":"bruno@postle.net","created_at":"2026-04-23T05:48:01Z","created_by":"Bruno Postle","updated_at":"2026-04-23T20:05:04Z","started_at":"2026-04-23T19:54:56Z","closed_at":"2026-04-23T20:05:04Z","close_reason":"Closed","dependencies":[{"issue_id":"ifcurl-i1s","depends_on_id":"ifcurl-49o","type":"blocks","created_at":"2026-04-23T07:14:12Z","created_by":"Bruno Postle","metadata":"{}"},{"issue_id":"ifcurl-i1s","depends_on_id":"ifcurl-4yu","type":"blocks","created_at":"2026-04-23T07:14:11Z","created_by":"Bruno Postle","metadata":"{}"},{"issue_id":"ifcurl-i1s","depends_on_id":"ifcurl-ach","type":"blocks","created_at":"2026-04-23T06:48:10Z","created_by":"Bruno Postle","metadata":"{}"},{"issue_id":"ifcurl-i1s","depends_on_id":"ifcurl-ahd","type":"blocks","created_at":"2026-04-23T07:02:54Z","created_by":"Bruno Postle","metadata":"{}"}],"dependency_count":4,"dependent_count":1,"comment_count":0}
 {"id":"ifcurl-ach","title":"Deploy Phase 3b footer template to Forgejo","description":"The footer.tmpl file that injects a 'View in 3D' button on .ifc file pages has been written but not yet deployed. Deploy it to /etc/forgejo/templates/custom/footer.tmpl and verify the button appears when viewing an .ifc file on localhost:3000.","status":"closed","priority":2,"issue_type":"task","owner":"bruno@postle.net","created_at":"2026-04-23T05:47:53Z","created_by":"Bruno Postle","updated_at":"2026-04-23T06:14:35Z","closed_at":"2026-04-23T06:14:35Z","close_reason":"Split into atomic tasks: ifcurl-ohq, ifcurl-49o","dependencies":[{"issue_id":"ifcurl-ach","depends_on_id":"ifcurl-ahd","type":"blocks","created_at":"2026-04-23T07:02:40Z","created_by":"Bruno Postle","metadata":"{}"}],"dependency_count":1,"dependent_count":1,"comment_count":0}
+{"id":"ifcurl-6ys","title":"Research alternative URL schemes before ifc:// is committed to","description":"The ifc:// scheme name is not yet set in stone. It's worth researching whether a different scheme would be more appropriate or less likely to conflict with existing tooling.\\n\\nLook at how other tools handle similar problems:\\n- pip uses git+https:// and git+ssh:// (prefix on top of existing schemes)\\n- Are there existing ifc:// registrations or tools that would conflict?\\n- What scheme patterns are used by other domain-specific version-controlled asset tools?\\n- Alternatives to consider: ifcgit://, git+ifc://, ifc+git://, or a vendor-prefixed form\\n- Check IANA registered schemes and common-use unregistered schemes for conflicts\\n\\nGoal: make a confident decision to keep ifc:// or switch, before the scheme is baked into any external integrations.","notes":"Research complete. Summary:\n\n- ifc is NOT registered with IANA. bcf, bim also unregistered. Clean namespace.\n- No existing tool or buildingSMART standard uses ifc:// — no conflict risk.\n- BCF (bcf://) would be confusing — BCF is a live buildingSMART standard, don't use it.\n- pip-style compound schemes (ifc+git://, ifc+https://) look appealing but hurt more than they help: they fragment the transport-inference design, improve nothing for OS handlers or terminal clickability, and are harder to explain.\n- Forgejo: CUSTOM_URL_SCHEMES defaults to allowing all schemes — ifc:// links render fine out of the box.\n- GitHub/terminals: bare custom URLs are never auto-linked regardless of scheme choice. Explicitly formatted markdown links work fine.\n\nDecision: keep ifc://\n\nAction to add to roadmap: submit a provisional IANA registration (First Come First Served, ~1 hour, just an email to iana@iana.org with scheme name, syntax summary, security notes, and a spec URL). Do this when Phase 1 spec stabilises.","status":"closed","priority":3,"issue_type":"task","assignee":"Bruno Postle","owner":"bruno@postle.net","created_at":"2026-04-25T09:08:13Z","created_by":"Bruno Postle","updated_at":"2026-04-25T11:17:44Z","started_at":"2026-04-25T11:04:50Z","closed_at":"2026-04-25T11:17:44Z","close_reason":"Keep ifc://. Namespace is clean (no IANA registration, no prior art). Compound schemes (ifc+git://) would break transport-inference design with no practical benefit. Action item: provisional IANA registration when Phase 1 spec stabilises.","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"id":"ifcurl-gy8","title":"Viewer: 'View in 3D' uses commit hash but no UI affordance to switch to branch tip","description":"The 'View in 3D' button in footer.tmpl always generates an ifc:// URL with a commit hash (@abc123...). This is correct for reproducibility, but users who want to track 'the latest version of main' must manually change the URL from @\u003chash\u003e to @heads/main. There is no indication in the viewer that the model is pinned to a specific commit. Add a visual indicator (e.g. 'commit abc1234 · switch to heads/main') in the viewer toolbar when the ref is a commit hash, offering a one-click switch to the branch tip. The branch name could be inferred from Forgejo's API given the commit hash.","status":"open","priority":3,"issue_type":"feature","owner":"bruno@postle.net","created_at":"2026-04-24T11:04:58Z","created_by":"Bruno Postle","updated_at":"2026-04-24T11:04:58Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"id":"ifcurl-dag","title":"Viewer: no model metadata panel — disciplines, spatial structure, element counts","description":"Beyond individual element selection, reviewers and designers need a model overview: what disciplines/types are present, how many elements, what building storeys exist, what's the spatial structure (site/building/storey/space hierarchy). A collapsible side panel showing IFC spatial tree and type breakdown would give immediate context and allow navigating by storey or discipline. Without this, reviewers must already know the model structure before opening the viewer.","status":"open","priority":3,"issue_type":"feature","owner":"bruno@postle.net","created_at":"2026-04-24T11:04:55Z","created_by":"Bruno Postle","updated_at":"2026-04-24T11:04:55Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"id":"ifcurl-ov6","title":"Viewer selector only supports type names — property filters require server round-trip","description":"The viewer's applySelector() only supports IFC type names and their unions ('IfcWall+IfcSlab'). Full IfcOpenShell selector syntax — filter by property value (Pset_WallCommon.FireRating=2HR), by GlobalId, by name (.Name='Core Wall'), by spatial containment — is not supported. For collaboration, reviewers need to select specific elements ('all walls with fire rating 2HR that aren't compliant') not just all walls. The service's /preview endpoint already handles full selector syntax server-side. The viewer should forward complex selectors to the service and use the rendered image, or fetch the matching GlobalIds from a new /resolve-selector service endpoint and apply them in the viewer.","status":"open","priority":3,"issue_type":"feature","owner":"bruno@postle.net","created_at":"2026-04-24T11:04:38Z","created_by":"Bruno Postle","updated_at":"2026-04-24T11:04:38Z","dependency_count":0,"dependent_count":0,"comment_count":0}
@@ -70,6 +71,7 @@
 {"id":"ifcurl-0oj","title":"Phase 4: Bonsai ifc:// OS protocol handler","description":"Register ifc:// as an OS protocol handler in Bonsai on installation (Windows, macOS, Linux). On receiving a URL, resolve the git source, load the model, and apply the view state from the URL parameters (camera, selector, clipping planes, visibility mode). This is the foundation for all other Phase 4 work.","status":"deferred","priority":3,"issue_type":"feature","owner":"bruno@postle.net","created_at":"2026-04-23T05:48:45Z","created_by":"Bruno Postle","updated_at":"2026-04-23T06:15:09Z","defer_until":"2026-12-01T00:00:00Z","dependency_count":0,"dependent_count":3,"comment_count":0}
 {"id":"ifcurl-cyw","title":"Phase 3c: Verify Forgejo merge-ability check works with ifcmerge","description":"Investigate whether Forgejo's merge-ability check (the 'branches can be merged automatically' indicator) correctly reflects ifcmerge's ability to handle .ifc files. Determine if Forgejo runs a trial git merge or uses a heuristic. If needed, patch Forgejo to run a trial git merge --no-commit to get an accurate result.","status":"closed","priority":3,"issue_type":"task","assignee":"Bruno Postle","owner":"bruno@postle.net","created_at":"2026-04-23T05:48:22Z","created_by":"Bruno Postle","updated_at":"2026-04-24T08:27:25Z","started_at":"2026-04-24T08:19:58Z","closed_at":"2026-04-24T08:27:25Z","close_reason":"Verified: git merge-tree --write-tree (Forgejo's code path for git ≥2.38) does invoke merge drivers. Bare repos require core.attributesFile in /etc/gitconfig — committed .gitattributes not read. Added gitattributes server-config file and updated deployment docs.","dependencies":[{"issue_id":"ifcurl-cyw","depends_on_id":"ifcurl-c69","type":"blocks","created_at":"2026-04-23T06:48:29Z","created_by":"Bruno Postle","metadata":"{}"}],"dependency_count":1,"dependent_count":0,"comment_count":0}
 {"id":"ifcurl-c69","title":"Phase 3c: Register ifcmerge as git merge driver on Forgejo server","description":"Configure ifcmerge as the git merge driver for .ifc files on the Forgejo server. Add to /etc/gitconfig or ~forgejo/.gitconfig: [merge \"ifcmerge\"] name = IFC merge driver / driver = ifcmerge %O %A %B %L. Add *.ifc merge=ifcmerge to server-side gitattributes. This allows Forgejo's 'merge automatically' path to invoke ifcmerge via git when merging .ifc files.","status":"closed","priority":3,"issue_type":"task","owner":"bruno@postle.net","created_at":"2026-04-23T05:48:21Z","created_by":"Bruno Postle","updated_at":"2026-04-24T08:15:20Z","closed_at":"2026-04-24T08:15:20Z","close_reason":"Documented ifcmerge driver registration (gitconfig-ifcmerge), gitattributes setup, merge direction constraint, and merge-commit strategy requirement","comments":[{"id":"019dbc54-bf0a-76e2-b64d-7d1681f0c730","issue_id":"ifcurl-c69","author":"Bruno Postle","text":"ifcmerge needs to be installed as a pair of merge tools because the merge process is asymmetrical and we need to be able to prefer one branch over another (because step-ids from one branch get rewritten in the merged file). In practice we prefer origin and/or main/master branches. there is code in the ifcopenshell bonsai ifcgit module for reference.","created_at":"2026-04-23T21:52:44Z"}],"dependency_count":0,"dependent_count":1,"comment_count":1}
+{"id":"ifcurl-nd1","title":"Submit provisional IANA registration for ifc:// scheme","description":"Once the Phase 1 URL spec is stable, submit a provisional IANA URI scheme registration for ifc://.\\n\\nProcess: email iana@iana.org with scheme name, syntax description, security considerations, and a link to the spec (GitHub URL suffices). First Come First Served — no committee review, typically processed within days to weeks. See RFC 7595 for requirements.\\n\\nThis secures the namespace, establishes priority, and is a prerequisite if the scheme is ever proposed to buildingSMART as an open standard.","status":"open","priority":4,"issue_type":"task","owner":"bruno@postle.net","created_at":"2026-04-25T11:17:45Z","created_by":"Bruno Postle","updated_at":"2026-04-25T11:17:45Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"id":"ifcurl-u6r","title":"Forgejo commit page: no IFC thumbnail — git log gives no visual indication of model state","description":"In the Forgejo repository commit list, each commit shows only the commit message. When a commit modifies an IFC file, there is no thumbnail showing what the model looks like. Reviewers browsing commits have no visual cues about which commits changed significant geometry versus metadata-only changes. A Forgejo webhook or CI integration could post a rendered PNG thumbnail as a commit status/check comment when .ifc files change, using the preview service. This would make the git log visually meaningful for BIM projects.","status":"open","priority":4,"issue_type":"feature","owner":"bruno@postle.net","created_at":"2026-04-24T11:04:41Z","created_by":"Bruno Postle","updated_at":"2026-04-24T11:04:41Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"id":"ifcurl-l50","title":"SPECIFICATION.md section 6: BCF-to-IFC-URL direction not implemented","description":"SPECIFICATION.md §6 defines both directions of BCF ↔ IFC URL conversion. The IFC URL → BCF direction is fully implemented (build_bcf(), /bcf endpoint, viewer BCF button). The BCF → IFC URL direction (extract GUIDs from Components/Selection, construct GUID selector, convert camera and clips to URL params) has no implementation. This would be useful for round-tripping: import a BCF viewpoint and get back a shareable ifc:// URL.","status":"open","priority":4,"issue_type":"feature","owner":"bruno@postle.net","created_at":"2026-04-24T10:41:01Z","created_by":"Bruno Postle","updated_at":"2026-04-24T10:41:01Z","dependency_count":0,"dependent_count":0,"comment_count":0}
 {"id":"ifcurl-8ns","title":"Future: Contribute ifc:// URL parsing to IfcOpenShell","description":"Once the Python core URL parsing and resolution logic is stable, contribute it to IfcOpenShell as a shared utility. Not a prerequisite for any phase — pursue after Phase 1 has been stable in production use for a while.","status":"open","priority":4,"issue_type":"task","owner":"bruno@postle.net","created_at":"2026-04-23T05:49:33Z","created_by":"Bruno Postle","updated_at":"2026-04-23T05:49:33Z","dependency_count":0,"dependent_count":0,"comment_count":0}