Date: 2026-03-17 Status: Planning / handoff pack Scope: Dependency-ordered backlog for the Workbench authority, tile tree, pane lifecycle, focus, persistence, and surface routing.

Related docs:

• WORKBENCH.md - workbench domain ownership and graph/workbench bridge rules
• pane_chrome_and_promotion_spec.md - pane promotion and chrome rules
• pane_presentation_and_locking_spec.md - pane lock and presentation authority
• workbench_frame_tile_interaction_spec.md - frame/tile interaction semantics
• tile_view_ops_spec.md - tile/view operation contract
• graph_first_frame_semantics_spec.md - graph/workbench first-frame rules
• ../domain_interaction_acceptance_matrix.md - compact review matrix for cross-domain scenario evidence
• ../../technical_architecture/domain_interaction_scenarios.md - canonical cross-domain scenario IDs (DI01-DI06)

• Hub issue: #306 (Hub: five-domain architecture adoption — Shell host, graphlet model, cross-domain scenarios)
• Primary implementation issue: #304 (Adopt the canonical graphlet model across Navigator and Workbench)
• Review/evidence issue: #305 (Operationalize cross-domain scenario IDs and acceptance evidence)

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The following slices are now landed in code and should be treated as backlog progress:

• ✅ Intent-carrier cleanup for navigator/workbench routing: legacy FileTree* variants were removed from active reducer/view-action paths, with canonical Navigator* carriers used at app/runtime boundaries. Advances: WB06, WB08.
• ✅ Navigator projection reset and state ownership paths now resolve through NavigatorProjectionState naming consistently across runtime/workspace state. Advances: WB03, WB05.
• ✅ Node pane now hosts collapsible Node History and Node Audit sections, backed by history query helpers instead of ad hoc pane-local state. Advances: WB17, WB21.

Remaining backlog IDs keep their existing done-gates unless explicitly closed by a dedicated closure receipt.

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1. WB01 Workbench Core Boundary. Depends: none. Done gate: one canonical doc distinguishes workbench authority from graph truth and renderer/session caches.
2. WB02 Tile Tree Ownership Audit. Depends: WB01. Done gate: every tile-tree mutation path is inventoried and tagged workbench-owned, graph-backed, or legacy violation.
3. WB03 Pane / Tile / Frame Glossary Lock. Depends: WB01. Done gate: Pane, Tile, Frame, Tab, ToolPane, and ArrangementObject each have one canonical definition.
4. WB04 Stable PaneId Coverage Audit. Depends: WB02, WB03. Done gate: every pane variant that can be opened, focused, split, or closed has a stable PaneId.
5. WB05 Workbench Truth vs Session State Contract. Depends: WB01, WB04. Done gate: durable arrangement truth is separated from session-only focus/open state.
6. WB06 Workbench Intent Inventory. Depends: WB02. Done gate: every current workbench action is mapped to WorkbenchIntent, graph bridge, or legacy helper.
7. WB07 Legacy Workbench Mutation Diagnostics. Depends: WB06. Done gate: direct tile-tree mutations outside workbench authority emit explicit diagnostics in development paths.
8. WB08 Open / Close / Focus Carrier Cleanup Plan. Depends: WB06, WB07. Done gate: every pane open, close, focus, split, and reorder path has one canonical carrier.
9. WB09 Workbench Contract Test Harness. Depends: WB02. Done gate: a test seam exists for split, close, focus, promotion, and restore behavior.
10. WB10 Single Workbench Mutation Path Closure Slice. Depends: WB07, WB09. Done gate: at least one major legacy workbench mutation cluster is removed and proven to flow only through workbench authority.

1. WB11 Tile Tree Semantic Contract. Depends: WB03, WB05. Done gate: tiles, tabs, and frames have explicit semantic ownership and lifecycle rules.
2. WB12 Tab Semantics Lock. Depends: WB11. Done gate: tabs are defined as entries within tiles, not a separate primary ontology.
3. WB13 Pane Promotion Contract. Depends: WB11, WB12. Done gate: promotion and demotion between solo, grouped, and tabbed states are defined with explicit carriers.
4. WB14 Split Semantics Contract. Depends: WB11. Done gate: horizontal and vertical split behavior, including resulting focus rules, is canonical.
5. WB15 Close Pane Contract. Depends: WB11, WB14. Done gate: close behavior is defined for graph, node, and tool panes with restore and focus fallthrough rules.
6. WB16 Restore and Reopen Contract. Depends: WB13, WB15. Done gate: restore/open previous focus behavior is explicit and testable.
7. WB17 Tool Pane Authority Audit. Depends: WB03, WB06. Done gate: settings, command palette, history, and similar panes all use workbench-owned routes.
8. WB18 Locking and Mutability Contract. Depends: WB11, WB17. Done gate: pane and frame lock states are defined with allowed and blocked operations.
9. WB19 Workbench Persistence Schema Audit. Depends: WB05, WB11. Done gate: durable workbench layout state is separated from ephemeral session state.
10. WB20 Workbench WAL Coverage Audit. Depends: WB19. Done gate: every durable workbench mutation is either WAL-logged or explicitly marked non-durable.

1. WB21 Focus Model Contract. Depends: WB11, WB15. Done gate: pane focus, tab focus, and frame focus are distinguished and routed consistently.
2. WB22 Selection-to-Workbench Targeting Rule. Depends: WB21. Done gate: selected objects that map to workbench actions become explicit workbench targets.
3. WB23 Workflow Activation Contract. Depends: WB19, WB21. Done gate: workflow/session-mode activation is explicit about runtime-owned versus persisted-default behavior.
4. WB24 Workbench Surface Diagnostics Pack. Depends: WB18, WB21, WB23. Done gate: blocked close, blocked split, focus failure, and restore failure all emit diagnostics.
5. WB25 Workbench Milestone Closure Receipt. Depends: WB01-WB24. Done gate: one closure doc states what workbench authority is canonical, what remains transitional, and what downstream lanes can safely assume.

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• WBS01 DI03 Linked arrangement around graphlet. Depends: WB08, WB11, WB16. Done gate: Workbench can create or focus a graphlet-linked arrangement while keeping graphlet truth external to arrangement ownership.
• WBS02 DI04 Viewer fallback in workbench-heavy session. Depends: WB15, WB21, WB24. Done gate: viewer fallback/degraded-state handling preserves pane placement and focus context and produces diagnosable evidence.
• WBS03 DI05 Shell overview frame/pane reorientation. Depends: WB21, WB24. Done gate: Shell overview handoff to focused frame/pane state is explicit, routed, and does not bypass workbench authority.