Skip to content
CSA Loom — the Microsoft Fabric experience for Azure tenants where Fabric isn't yet available: lakehouses, warehouses, notebooks, semantic models, Activator rules, Data Agents, across Commercial, GCC, GCC-High, and DoD IL5

Loom Semantic Model — Fabric parity gap

Validator: v2 4-phase (live browser) — 2026-05-26 Loom URL: https://loom-console-fvbbctd4eehqbkcs.b02.azurefd.net/items/semantic-model/new Fabric reference: https://app.fabric.microsoft.com (casino-fabric-poc workspace) — login-gated; spec-derived from docs/fiab/semantic-model-parity-spec.md and Microsoft Learn Power BI desktop docs. Screenshots: temp/parity/semantic-model-loom.png (full page) · temp/parity/fabric-login-gate.png (Fabric requires interactive MFA) Source under review: apps/fiab-console/lib/editors/phase3-editors.tsx lines 1325-1538

Phase 1 + 2 captures

Live Loom DOM (heading + ribbon, captured 2026-05-26): - Heading: New semantic model - Subtitle: Tables, relationships, measures, and roles backing Power BI reports. - Ribbon tab: Home only (vs Fabric: Home + Modeling + View + Help) - Ribbon buttons: New measure, New role, New perspective, Refresh, Direct Lake, Import, plus toolbar Refresh + Refresh dataset - Monaco editor present: NO - Textareas in <main>: 0 - <iframe> count: 0 - Fluent MessageBar count: 0

Phase 3 — Side-by-side gap matrix

Fabric element Loom present? Severity Notes
Ribbon — Home (New measure / New parameter / Save / Refresh) partial — has "New measure" label only, no Save, no New parameter MAJOR Buttons are labels; click does nothing
Ribbon — Modeling (Manage Relationships · New Column · View As · Data Category) MISSING BLOCKER No Modeling tab at all
Ribbon — View (Model View · Data View · Expression Editor toggle · Zoom · Layout) MISSING BLOCKER No View tab
Ribbon — Help MISSING MINOR No Help tab
Model View canvas (visual table+relationship designer with drag-drop, cardinality glyphs, bi-directional arrows) MISSING BLOCKER No canvas exists; Loom shows a flat HTML <Table> of column/measure names
Relationship designer (drag-drop FK, cardinality picker, filter direction toggle, active/inactive, ambiguity detector, USERELATIONSHIP) MISSING BLOCKER Loom "Relationships" tab renders only the text "Power BI REST returns relationships only via the XMLA endpoint (TMSL). Click Refresh dataset to validate metadata; full TMSL graph rendering lands in v2.2." — no UI
DAX Editor (syntax highlighting, intellisense for [Measure]/Column/Table, formula validation, format-string picker, commit/cancel) MISSING BLOCKER Loom "Measures (DAX)" tab is a read-only <pre> block of m.expression — NO editor, NO Monaco, NO highlighting, NO completion. Cannot CREATE a measure.
Data preview / Table View (sortable columns, type indicators, row count, filters, scroll) MISSING BLOCKER Loom Tables tab is a flat Table with column-list strings; no data rows from the model
Row-Level Security (RLS) editor (role + DAX filter + Test as Role) MISSING BLOCKER Ribbon has a "New role" label that does nothing on click
Properties / Formatting panes (display name vs internal, Hidden toggle, Synonyms, Data Category, Format string, Sort by) MISSING BLOCKER No right-rail property pane at all
"View As" RLS simulation MISSING BLOCKER Not present
Direct Lake / Import / DirectQuery mode picker label-only MAJOR Buttons "Direct Lake" and "Import" exist as labels, no handler
Save MISSING MAJOR No Save button anywhere in the ribbon
Cosmos persistence of model definition (state.tables/measures/relationships) per parity-spec line 60-63 the spec claims this exists, but the editor does not expose a write surface MAJOR Editor reads via /api/items/semantic-model/{id} but has no create/edit/persist flow — only Refresh dataset
Refresh dataset (POST /datasets/{id}/refreshes) PRESENT but gated MINOR Button is disabled until a dataset is selected from the (empty by default) list; once workspace+dataset chosen, the POST is wired
Refresh history list PRESENT — Table renders rows from /api/items/semantic-model/{id}/refreshes

Phase 4 — Functional click-every-button verification

Performed via Playwright on the live Loom URL while the route was stable at /items/semantic-model/new:

Button (ribbon) Action Observed result Status
New measure Click → expect DAX editor dialog NO modal, NO Monaco, NO textarea appeared in DOM; dialogs=0, monaco=false, textareas=0 BROKEN — primary action no-op
New role Click → expect RLS role dialog Same: nothing happened BROKEN
New perspective Click → expect perspective dialog Same: nothing happened BROKEN
Direct Lake Click → expect storage-mode picker Same: nothing happened BROKEN
Import Click → expect import picker Same: nothing happened BROKEN
Refresh (ribbon) Click → ribbon group Refresh Same: nothing happened BROKEN
Refresh dataset (toolbar) Click → POST /api/items/semantic-model/{id}/refresh Disabled until dataset selected; once enabled, wired to real Power BI REST (verified via source) OK (gated)
Refresh (toolbar) Click → reload dataset list Wired (loadList) — works once workspaceId chosen OK (gated)

Root cause (source-level): SM_RIBBON (phase3-editors.tsx:1327) is a RibbonTab[] where every RibbonAction carries only { label } with no onClick. The Ribbon component (lib/components/ribbon.tsx:96-103) spreads ...rest to <Button>, which means the spread is empty — these buttons literally have no click handler attached.

Final grade

Grade: D (multiple BLOCKERS)

Per parity-validation-standard: - Phase 3 has 9 BLOCKER rows (no Model View canvas, no Modeling ribbon tab, no View tab, no relationship designer, no DAX editor, no data preview, no RLS editor, no Properties pane, no View As). - Phase 4 has 6 BROKEN primary controls (New measure is the most damning — it is the headline action of a semantic-model editor and it does nothing). - Only Refresh dataset / Refresh list buttons function, and only when a real Power BI workspace + dataset is already provisioned.

The editor is best described as a read-only metadata viewer that lists tables, columns, and measure names harvested from /api/items/semantic-model/{id}. It is not a semantic-model editor.

  1. Replace the DAX <pre> viewer with Monaco (@monaco-editor/react) configured language="dax" (use monaco-dax or register a custom DAX tokenizer + completion provider seeded with CALCULATE / SUM / SUMX / DIVIDE / FILTER / RELATED and the model's column/measure names from detail.tables). Add error squiggles via setModelMarkers. Theme: vs-dark.
  2. Wire New measure to open a Dialog with the Monaco DAX editor + measure-name input + format-string picker + Save → POST /api/items/semantic-model/{id}/measures (route does not yet exist; add it + the BFF call to PBI XMLA / TMSL).
  3. Build a Modeling ribbon tab with real handlers for Manage relationships, New column, View As, Data Category — each opening the appropriate dialog.
  4. Build a Model View canvas — start with a flat SVG / Mermaid representation of detail.tables + relationships. Render a card per table with column rows. Render edges with cardinality labels. Drag-drop is Phase 2.
  5. Build an RLS pane — wire New role to open a role-creation dialog with a Monaco DAX filter editor + role-name + "Test as Role" toggle. Persist via TMSL.
  6. Add an honest MessageBar for features blocked on tenant config (XMLA endpoint enable, Direct Lake capacity assignment) per no-vaporware.md rather than leaving label-only buttons.
  7. Bicep sync: TMSL execution requires the XMLA endpoint on a Premium / Fabric capacity. Document the capacity SKU + tenant setting "XMLA endpoint = Read/Write" in docs/fiab/v3-tenant-bootstrap.md and add the workspace-to-capacity assignment to platform/fiab/bicep/.

Estimated effort to reach grade B: 3-4 focused sessions (Monaco DAX + measure dialog + RLS pane + flat Model View). Grade A requires the visual canvas + drag-drop relationship designer — add 2 more sessions.