Refactor: Split 4 large files for clarity

- `friendly_error.rs` (1805 lines) → extract provider detection into `provider.rs`
- `ai/manager.rs` → extract system memory measurement into top-level `system_memory.rs`
- `AiSection.svelte` (1582 lines) → split into `AiCloudSection` + `AiLocalSection`
- `+page.svelte` (1222→750 lines) → extract `command-dispatch.ts`, `mcp-listeners.ts`, `explorer-api.ts`

Author: vdavid

AGENTS.md

@@ -159,7 +159,7 @@ resilience, and common pitfalls.
   `var(--font-size-*)`, `var(--radius-*)`, `var(--font-*)`, and `var(--z-*)` tokens. Stylelint enforces this.
 - **Coverage allowlist is a last resort.** Extract pure functions and test them. Only allowlist what genuinely can't be
   tested. Name the specific untestable API in the reason.
-- When adding a new user-facing action, add it to `command-registry.ts` and `handleCommandExecute` in `+page.svelte`.
+- When adding a new user-facing action, add it to `command-registry.ts` and `handleCommandExecute` in `routes/(main)/command-dispatch.ts`.
 - If you added a new Tauri command touching the filesystem, check `docs/architecture.md` § Platform constraints.
 - We use [mise](https://mise.jdx.dev/) to manage tool versions (Go, Node, etc.), pinned in `.mise.toml`. Shims are on
   PATH via `~/.bashrc` and `~/.zshenv`, so `go` and `node` should just work. If `go` is "not found", check that

apps/desktop/coverage-allowlist.json

@@ -38,9 +38,6 @@
     "file-explorer/pane/FilePane.svelte": { "reason": "Tested in integration.test.ts, complex component" },
     "file-explorer/pane/MtpConnectionView.svelte": { "reason": "MTP connection UI, depends on Tauri APIs" },
     "file-explorer/pane/NetworkMountView.svelte": { "reason": "Network mount UI, depends on Tauri APIs" },
-    "file-explorer/pane/initialization.ts": {
-      "reason": "Happy path covered by DualPaneExplorer tests; timeout and E2E override branches tested via E2E in CI"
-    },
     "file-explorer/pane/rename-flow.svelte.ts": {
       "reason": "Extracted from FilePane, depends on Tauri commands and rename operations"
     },
@@ -213,6 +210,12 @@
       "reason": "UI component, simple show/hide toggle + settings store wiring"
     },
     "settings/sections/AiSection.svelte": {
+      "reason": "UI section, thin wrapper for AI provider toggle"
+    },
+    "settings/sections/AiCloudSection.svelte": {
+      "reason": "UI section, depends on Tauri commands and event listeners"
+    },
+    "settings/sections/AiLocalSection.svelte": {
       "reason": "UI section, depends on Tauri commands and event listeners"
     },
     "search/AiSearchRow.svelte": {

apps/desktop/src-tauri/src/ai/CLAUDE.md

@@ -21,7 +21,7 @@ Three provider modes:
 
 ### Tauri commands
 
-Core: `get_ai_status`, `get_ai_model_info`, `get_ai_runtime_status`, `configure_ai`, `start_ai_server`, `stop_ai_server`, `check_ai_connection`, `start_ai_download`, `cancel_ai_download`, `get_folder_suggestions`.
+Core: `get_ai_status`, `get_ai_model_info`, `get_ai_runtime_status`, `configure_ai`, `start_ai_server`, `stop_ai_server`, `check_ai_connection`, `start_ai_download`, `cancel_ai_download`, `get_folder_suggestions`. Note: `get_system_memory_info` moved to top-level `system_memory.rs`.
 Legacy (still wired, used by toast): `uninstall_ai`, `dismiss_ai_offer`, `opt_out_ai`, `opt_in_ai`, `is_ai_opted_out`.
 
 ## Startup flow

apps/desktop/src-tauri/src/ai/manager.rs

@@ -365,114 +365,6 @@ pub fn get_ai_runtime_status() -> AiRuntimeStatus {
     }
 }
 
-/// System memory breakdown returned to frontend for the RAM gauge.
-/// Categories are non-overlapping and sum to `total_bytes`.
-#[derive(Debug, Clone, serde::Serialize, PartialEq, Eq)]
-#[serde(rename_all = "camelCase")]
-pub struct SystemMemoryInfo {
-    pub total_bytes: u64,
-    /// Wired + compressor-occupied memory (kernel, drivers — can't be freed).
-    pub wired_bytes: u64,
-    /// App memory: active + inactive - purgeable (process memory the user can free by quitting apps).
-    pub app_bytes: u64,
-    /// Free: free + purgeable + speculative (available for new allocations).
-    pub free_bytes: u64,
-}
-
-/// Returns system memory breakdown using macOS `host_statistics64` for accurate,
-/// non-overlapping categories (unlike `sysinfo` where used + available > total).
-#[tauri::command]
-pub fn get_system_memory_info() -> SystemMemoryInfo {
-    get_system_memory_info_inner()
-}
-
-/// Testable inner function that reads macOS vm_statistics64 via Mach API.
-pub fn get_system_memory_info_inner() -> SystemMemoryInfo {
-    #[cfg(target_os = "macos")]
-    {
-        macos_memory_info()
-    }
-    #[cfg(not(target_os = "macos"))]
-    {
-        // Fallback for non-macOS: use sysinfo (best effort)
-        let mut sys = sysinfo::System::new();
-        sys.refresh_memory();
-        let total = sys.total_memory();
-        let used = sys.used_memory();
-        let free = total.saturating_sub(used);
-        SystemMemoryInfo {
-            total_bytes: total,
-            wired_bytes: 0,
-            app_bytes: used,
-            free_bytes: free,
-        }
-    }
-}
-
-/// Reads macOS vm_statistics64 via `host_statistics64` for accurate memory breakdown.
-#[cfg(target_os = "macos")]
-fn macos_memory_info() -> SystemMemoryInfo {
-    use std::mem;
-
-    let total_bytes = {
-        let mut sys = sysinfo::System::new();
-        sys.refresh_memory();
-        sys.total_memory()
-    };
-
-    // Safety: calling Mach kernel API with proper struct size.
-    let page_size: u64;
-    let (wired_pages, compressor_pages, internal_pages, purgeable_pages);
-
-    unsafe {
-        page_size = libc::sysconf(libc::_SC_PAGESIZE) as u64;
-
-        #[allow(deprecated, reason = "libc says use mach2, but not worth a new dep for one call")]
-        let host = libc::mach_host_self();
-        let mut vm_info: libc::vm_statistics64 = mem::zeroed();
-        let mut count = (size_of::<libc::vm_statistics64>() / size_of::<libc::integer_t>()) as u32;
-
-        let ret = libc::host_statistics64(
-            host,
-            libc::HOST_VM_INFO64,
-            &mut vm_info as *mut _ as *mut libc::integer_t,
-            &mut count,
-        );
-
-        if ret != libc::KERN_SUCCESS {
-            log::warn!("host_statistics64 returned {ret}, falling back to sysinfo");
-            let mut sys = sysinfo::System::new();
-            sys.refresh_memory();
-            let used = sys.used_memory();
-            return SystemMemoryInfo {
-                total_bytes,
-                wired_bytes: 0,
-                app_bytes: used,
-                free_bytes: total_bytes.saturating_sub(used),
-            };
-        }
-
-        wired_pages = vm_info.wire_count as u64;
-        compressor_pages = vm_info.compressor_page_count as u64;
-        // internal_page_count = anonymous pages owned by processes (what Activity Monitor calls "App Memory").
-        // Unlike active+inactive, this excludes file-backed cache that macOS freely reclaims.
-        internal_pages = vm_info.internal_page_count as u64;
-        purgeable_pages = vm_info.purgeable_count as u64;
-    }
-
-    let wired_bytes = (wired_pages + compressor_pages) * page_size;
-    let app_bytes = internal_pages.saturating_sub(purgeable_pages) * page_size;
-    // Free = everything not wired or app (includes file cache, inactive, purgeable, speculative)
-    let free_bytes = total_bytes.saturating_sub(wired_bytes + app_bytes);
-
-    SystemMemoryInfo {
-        total_bytes,
-        wired_bytes,
-        app_bytes,
-        free_bytes,
-    }
-}
-
 /// Stores provider + context size + OpenAI config in manager state.
 /// If provider is `local` and model is installed and hardware is supported, starts the server
 /// in a background task. If provider is NOT `local` and a server is running, stops it.
@@ -1093,40 +985,4 @@ mod tests {
         let status = get_ai_status();
         assert_eq!(status, AiStatus::Unavailable);
     }
-
-    #[test]
-    fn test_system_memory_info_adds_up() {
-        let info = get_system_memory_info_inner();
-
-        // Total must be positive (every machine has RAM)
-        assert!(info.total_bytes > 0, "total_bytes should be positive");
-
-        // Non-overlapping segments must sum to total
-        let sum = info.wired_bytes + info.app_bytes + info.free_bytes;
-        assert_eq!(
-            sum, info.total_bytes,
-            "wired ({}) + app ({}) + free ({}) = {} != total ({})",
-            info.wired_bytes, info.app_bytes, info.free_bytes, sum, info.total_bytes,
-        );
-
-        // Each segment should be reasonable (not more than total)
-        assert!(info.wired_bytes <= info.total_bytes);
-        assert!(info.app_bytes <= info.total_bytes);
-        assert!(info.free_bytes <= info.total_bytes);
-    }
-
-    #[test]
-    fn test_system_memory_info_serialization() {
-        let info = SystemMemoryInfo {
-            total_bytes: 68_719_476_736,
-            wired_bytes: 5_000_000_000,
-            app_bytes: 30_000_000_000,
-            free_bytes: 33_719_476_736,
-        };
-        let json = serde_json::to_string(&info).unwrap();
-        assert!(json.contains("\"totalBytes\":68719476736"));
-        assert!(json.contains("\"wiredBytes\":5000000000"));
-        assert!(json.contains("\"appBytes\":30000000000"));
-        assert!(json.contains("\"freeBytes\":33719476736"));
-    }
 }

apps/desktop/src-tauri/src/file_system/volume/CLAUDE.md

@@ -11,7 +11,8 @@ Every file system operation (listing, copy, rename, delete, indexing, watching)
 | File | Role |
 |---|---|
 | `mod.rs` | `Volume` trait, `VolumeScanner`, `VolumeWatcher`, `VolumeReadStream` traits, `MutationEvent` enum, shared types (`VolumeError`, `SpaceInfo`, `CopyScanResult`, `ScanConflict`, `SourceItemInfo`) |
-| `friendly_error.rs` | User-facing error messages. See [Friendly error system](#friendly-error-system) below. |
+| `friendly_error.rs` | User-facing error messages: `FriendlyError`, `ErrorCategory`, errno mapping. See [Friendly error system](#friendly-error-system) below. |
+| `provider.rs` | Provider detection and enrichment: `Provider` enum (19 variants), `detect_provider()`, `provider_suggestion()`, `enrich_with_provider()`. Re-exported via `friendly_error.rs`. |
 | `manager.rs` | `VolumeManager` — thread-safe `RwLock<HashMap>` registry; supports a default volume |
 | `local_posix.rs` | `LocalPosixVolume` — real filesystem; delegates listing to `file_system::listing`, indexing to `indexing::scanner`, watching to `indexing::watcher` (FSEvents), copy scanning via `walkdir`. Uses `libc::statvfs` FFI for space info. |
 | `mtp.rs` | `MtpVolume` — MTP device storage; synchronous `Volume` trait bridged to async MTP calls via `tokio::runtime::Handle::block_on`. Gated with `#[cfg(any(target_os = "macos", target_os = "linux"))]`. |
@@ -93,12 +94,14 @@ collapsible "Technical details" section, never hidden but never in your face eit
 
 ### Architecture
 
-Two-layer mapping, both in this file:
+Two-layer mapping across two files:
 
-1. **`friendly_error_from_volume_error(err, path)`** — maps `VolumeError` variants and macOS errno codes (37 codes) to a
-   `FriendlyError` with category (Transient/NeedsAction/Serious), title, explanation, suggestion, and raw detail.
-2. **`enrich_with_provider(error, path)`** — detects 19 cloud/mount providers from path patterns and `statfs` filesystem
-   type, then overwrites the suggestion with provider-specific advice.
+1. **`friendly_error_from_volume_error(err, path)`** (`friendly_error.rs`) — maps `VolumeError` variants and macOS errno
+   codes (37 codes) to a `FriendlyError` with category (Transient/NeedsAction/Serious), title, explanation, suggestion,
+   and raw detail.
+2. **`enrich_with_provider(error, path)`** (`provider.rs`, re-exported from `friendly_error.rs`) — detects 19
+   cloud/mount providers from path patterns and `statfs` filesystem type, then overwrites the suggestion with
+   provider-specific advice.
 
 The frontend receives the fully-baked `FriendlyError` struct via the `listing-error` Tauri event and renders it with
 category-based visual styling. The frontend never sees errno codes or does OS-specific logic.