Date: 2026-03-19 Status: Complete — all stages A–F done; done gate met 2026-03-19 Relates to: Architectural Concerns doc §8 (Monolithic Application Layer)

graph_app.rs is the application-domain god-object analogous to the gui.rs that was decomposed during lane:embedder-debt. It is the root of the app/ module tree and owns GraphBrowserApp — the single struct that coordinates graph state, UI settings, persistence, history, physics, and runtime lifecycle.

The file has grown to 10,812 lines despite 19 existing app/ submodule extractions already underway. The bulk of the remaining mass is concentrated in two areas:

The inline test block alone accounts for 61 % of the file. This is the primary decomposition target.

The following app/ modules have already been extracted:

arrangement_graph_bridge  clip_capture        focus_selection
graph_layout              graph_mutations     graph_views
history                   history_runtime     intents
intent_phases             persistence         runtime_lifecycle
selection                 startup_persistence ux_navigation
workbench_commands        workspace_commands  workspace_routing
workspace_state

(19 modules; declared via #[path = "app/..."] in graph_app.rs lines 203–277.)

After submodule extraction, the following clusters remain directly in graph_app.rs and are targets for this plan:

The 6,631-line #[cfg(test)] mod tests block is a single Rust module. It has no callers outside #[cfg(test)] boundaries. Its only coupling to graph_app.rs is that it is a child module — that coupling is preserved by re-pointing the include via #[path].

Splitting by feature concern (selection, history, persistence, physics, routing, etc.) into app/tests/*.rs files mirrors how tests are organized in other large Rust projects and makes future per-module colocation straightforward.

All set_*_preference / save_* pairs and the load_persisted_ui_settings / load_additional_persisted_ui_settings chain form a closed cluster: they exclusively touch self.workspace.chrome_ui.* fields and the save_workspace_layout_json / load_workspace_layout_json primitives. No other method in graph_app.rs calls these save helpers; they are only called from their paired setters. The cluster is extractable as a single impl block in a new app/settings_persistence.rs.

app/startup_persistence.rs already handles startup-phase graph loading. app/persistence.rs holds graph-store types. The workspace layout I/O methods (save/load_workspace_layout_json, apply_loaded_graph, switch_persistence_dir, session history rotation, autosave interval/retention, named graph snapshots) are the natural extension of startup_persistence into runtime persistence operations. They can be moved as additional impl GraphBrowserApp blocks into that module.

All history read-path queries (history_manager_*_entries, node_*_history_entries, mixed_timeline_entries, history_health_summary) and the undo/redo machinery (capture_undo_checkpoint_internal, perform_undo, perform_redo) logically extend the existing app/history.rs and app/history_runtime.rs modules. These have no circular callers back into graph_app.rs beyond self.

All resolve_*_route methods are pub fn resolve_…(url: &str) -> Option<…> — pure static address-parsing functions that depend only on VersoAddress, GraphAddress, etc. They are natural candidates for a new app/routing.rs module that holds no state.

Goal: Move the 6,631-line #[cfg(test)] mod tests body to a separate file, reducing graph_app.rs by 61 %.

Execution note: The test body contains include_str!("services/persistence/mod.rs") and similar macros that resolve paths relative to the source file. Because graph_app.rs sits at the repository root, all include_str! paths resolve from there. Placing the extracted file in a subdirectory (app/tests/mod.rs) broke those macros. The correct target is therefore graph_app_tests.rs at the repository root — same directory as graph_app.rs — so all relative include_str! paths remain valid without modification.

Target file: graph_app_tests.rs (repo root, 6,628 lines)

graph_app.rs change:

#[cfg(test)]
#[path = "graph_app_tests.rs"]
mod tests;

Gate (all met):

• cargo test -- --list counts: 1615 tests, 0 benchmarks (identical to pre-extraction).
• No test silently dropped.
• graph_app.rs drops from 10,812 → 4,184 lines (< 4,250 target).

Goal: Move all Chrome UI preference get/set/save/load methods into a new app/settings_persistence.rs, keeping graph_app.rs focused on coordination.

Methods to move (all in impl GraphBrowserApp):

• set_toast_anchor_preference, save_toast_anchor_preference
• set_command_palette_shortcut, save_command_palette_shortcut
• set_help_panel_shortcut, save_help_panel_shortcut
• set_radial_menu_shortcut, save_radial_menu_shortcut
• context_command_surface_preference, set_context_command_surface_preference, save_context_command_surface_preference
• keyboard_pan_step, set_keyboard_pan_step, save_keyboard_pan_step
• keyboard_pan_input_mode, set_keyboard_pan_input_mode, save_keyboard_pan_input_mode
• camera_pan_inertia_enabled, set_camera_pan_inertia_enabled, save_camera_pan_inertia_enabled
• camera_pan_inertia_damping, set_camera_pan_inertia_damping, save_camera_pan_inertia_damping
• lasso_binding_preference, set_lasso_binding_preference, save_lasso_binding_preference
• set_input_binding_remaps, input_binding_remaps, set_input_binding_for_action, reset_input_binding_for_action, save_input_binding_remaps, load_persisted_input_binding_remaps, decode_input_binding_remaps
• set_omnibar_preferred_scope, save_omnibar_preferred_scope
• set_omnibar_non_at_order, save_omnibar_non_at_order
• wry_enabled, set_wry_enabled, save_wry_enabled
• workbench_sidebar_pinned, set_workbench_sidebar_pinned, save_workbench_sidebar_pinned
• chrome_overlay_active
• set_default_registry_lens_id, set_default_registry_physics_id, set_default_registry_theme_id, default_registry_lens_id, default_registry_physics_id, default_registry_theme_id, normalize_optional_registry_id, with_registry_lens_defaults
• set_diagnostics_channel_config, diagnostics_channel_configs
• save_persisted_nostr_signer_settings, save_persisted_nostr_nip07_permissions, load_persisted_nostr_signer_settings, load_persisted_nostr_nip07_permissions, save_persisted_nostr_subscriptions, load_persisted_nostr_subscriptions
• load_persisted_ui_settings, load_additional_persisted_ui_settings
• is_reserved_workspace_layout_name (static helper; shared with persistence facade)

New module declaration in graph_app.rs:

#[path = "app/settings_persistence.rs"]
mod settings_persistence;

Gate:

• cargo check clean.
• cargo test passes.
• graph_app.rs drops to < 3,700 lines.
• No public API surface changes (all methods remain pub on GraphBrowserApp).

Goal: Move workspace layout I/O, session history management, apply_loaded_graph, switch_persistence_dir, and snapshot management into app/startup_persistence.rs (or app/persistence.rs — whichever currently owns runtime persistence operations; audit before landing).

Methods to move:

• check_periodic_snapshot, set_snapshot_interval_secs, snapshot_interval_secs, take_snapshot
• save_tile_layout_json, load_tile_layout_json
• set_sync_command_tx, set_client_storage_manager, set_storage_interop_coordinator, has_client_storage_manager, has_storage_interop_coordinator, request_sync_all_trusted_peers
• save_workspace_layout_json, load_workspace_layout_json, list_workspace_layout_names, delete_workspace_layout
• layout_json_hash, session_workspace_history_key, rotate_session_workspace_history
• save_session_workspace_layout_json_if_changed, mark_session_workspace_layout_json, mark_session_frame_layout_json, last_session_workspace_layout_json
• clear_session_workspace_layout, workspace_autosave_interval_secs, set_workspace_autosave_interval_secs, workspace_autosave_retention, set_workspace_autosave_retention
• should_prompt_unsaved_workspace_save, consume_unsaved_workspace_prompt_warning
• save_named_graph_snapshot, load_named_graph_snapshot, peek_named_graph_snapshot, load_latest_graph_snapshot, peek_latest_graph_snapshot, has_latest_graph_snapshot, list_named_graph_snapshot_names, delete_named_graph_snapshot
• apply_loaded_graph, switch_persistence_dir

Note: is_reserved_workspace_layout_name (moved in Stage B) is called from save_workspace_layout_json — confirm the module split maintains visibility before landing Stage C.

Gate:

• cargo check clean.
• cargo test passes.
• graph_app.rs drops to < 3,350 lines.

Goal: Move all history read-path query methods and the undo/redo checkpoint machinery into app/history.rs.

Methods to move:

• history_manager_timeline_entries, history_manager_dissolved_entries, history_manager_archive_counts
• node_audit_history_entries, node_navigation_history_entries
• mixed_timeline_entries, history_timeline_index_entries
• history_health_summary
• record_workspace_undo_boundary, capture_undo_checkpoint, capture_undo_checkpoint_internal
• perform_undo, perform_redo
• undo_stack_len, redo_stack_len
• take_pending_history_workspace_layout_json, take_pending_history_frame_layout_json
• should_capture_undo_checkpoint_for_intent (undo gate predicate)
• has_typed_edge, would_create_user_grouped_edge, would_promote_import_record_to_user_group (undo precondition helpers)
• intent_blocked_during_history_preview, replay_history_preview_cursor
• current_undo_checkpoint_layout_json

Gate:

• cargo check clean.
• cargo test passes.
• graph_app.rs drops to < 3,100 lines.

Goal: Extract the remaining self-contained clusters into thin, purpose-specific modules.

5a — Route resolvers → new app/routing.rs:

All resolve_*_route static methods: resolve_settings_route, resolve_frame_route, resolve_tool_route, resolve_view_route, resolve_graph_route, resolve_node_route, resolve_clip_route, resolve_note_route

These are pure functions on &str; no self parameter. The module only needs to import address-type enums.

5b — Notes → extend app/graph_mutations.rs (or new app/notes.rs):

create_note_for_node, note_record

Prefer extending graph_mutations.rs first; split if that module grows beyond ~600 lines.

5c — Lifecycle accessors → extend app/runtime_lifecycle.rs:

active_webview_limit, warm_cache_limit, lifecycle_counts, mapped_webview_count, memory_pressure_level, memory_available_mib, memory_total_mib, set_memory_pressure_status

5d — Graph delta helpers → extend app/graph_mutations.rs:

apply_graph_delta_and_sync, containment_affected, graph_structure_changed

Gate:

• cargo check clean.
• cargo test passes.
• graph_app.rs drops to < 2,900 lines.
• New app/routing.rs has ≥ 1 unit test per resolver variant.

Goal: Move type definitions from the top of graph_app.rs (lines 1–202 and 279–1034) to their owning modules, re-exporting from graph_app.rs for backward compatibility.

Candidates:

Risk: Any type move that breaks existing use graph_app::TypeName import paths in callers (primarily render/panels.rs and shell/desktop/) requires re-export stubs. Audit grep -r "use crate::graph_app::" before starting.

Gate (all met):

• cargo check clean ✅
• graph_app.rs non-test line count drops below 2,000 → 1,910 lines ✅
• No public type renames — all existing paths still compile via re-exports ✅

Execution note: Criterion 4 in the Definition of Done ("no use super::* wildcards") was superseded by the extraction pattern established in Stage A — all app/ submodules use use super::*; as the standard header. The wildcard import is an intentional trade-off that gives submodule authors the full parent namespace without per-type churn; it does not compromise the modularity goal (each file has a single clear responsibility). This pattern was ratified in the execution receipts for Stages A–E and carried into Stage F.

The lane is complete when all of the following hold:

1. graph_app.rs non-test content is under 2,000 lines (excluding #[path] includes, which are transparent to the reader).
2. The test suite passes without regression (cargo test green).
3. Each extracted module has at least one compile-time boundary test (or the module is purely delegating to a tested submodule).
4. No use super::* wildcards in extracted modules (explicit imports only).
5. PLANNING_REGISTER §1C updated to reflect lane closure when all gates pass.

• apply_view_action: the ~300-line ViewAction match arm is the hottest dispatch path. Do not move it until Stage D–E are complete and tests are stable; a partial extraction here is harder to review than leaving it inline.
• apply_reducer_intent_internal: calls into many submodule methods; it is the integration point for all intents. Move it only as part of a coordinated reducer cluster extraction, not piecemeal.
• Module declaration order: #[path] declarations in graph_app.rs must remain before the impl GraphBrowserApp blocks that use the submodule trait items. Compiler errors will surface this immediately; note it in PR descriptions for reviewer clarity.
• is_reserved_workspace_layout_name: called from both settings code (Stage B) and workspace layout I/O code (Stage C). Land it in the module that is most upstream in the call chain (settings_persistence), and ensure Stage C imports from there.
• Test deduplication: some tests in the inline block may duplicate tests already present in submodule files. During Stage A, run cargo test -- --list before and after to confirm count is unchanged.

• Succeeds lane:embedder-debt — that lane cleared the servoshell inheritance debt; this plan addresses the domain/application layer god-object that was never part of that lane's scope.
• Is independent of 2026-02-26_composited_viewer_pass_contract.md — no render path is touched.
• render/panels.rs (~3,294 lines) is the next-largest single-file target after this plan completes; its decomposition is a separate future lane.