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feat: implement seamless local network sync via mDNS and CRDTs#45

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feat-local-network-sync-6380593602282876537
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feat: implement seamless local network sync via mDNS and CRDTs#45
Keshav-writes-code wants to merge 18 commits intofeat/local_syncfrom
feat-local-network-sync-6380593602282876537

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@Keshav-writes-code Keshav-writes-code commented Mar 6, 2026

Implements the Apple-like seamless local network sync feature for Markdown notes.

Features

  1. Device Discovery & Pairing: Uses mDNS (mdns-sd crate) to broadcast and discover instances of the application on the local network. A simple 6-digit PIN mechanism authenticates and establishes trust between devices.
  2. Conflict Resolution: Integrates the automerge crate to manage files using Conflict-free Replicated Data Types (CRDTs). The app projects CRDT history to the visible .md files and maintains a hidden .sync/ directory for metadata.
  3. Background Sync (Android): Implements an Android ForegroundService to keep the sync process alive in the background.
  4. Local Network API: Runs a lightweight axum HTTP server within the Rust backend to exchange pairing statuses and (eventually) CRDT payloads.
  5. Frontend Settings: Adds a "Sync Devices" modal to the sidebar that allows users to enable/disable the feature, view their PIN, and connect to discovered peers.

PR created automatically by Jules for task 6380593602282876537 started by @Keshav-writes-code

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google-labs-jules bot commented Mar 6, 2026

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@Keshav-writes-code Keshav-writes-code force-pushed the feat-local-network-sync-6380593602282876537 branch from be4286f to 5632e5a Compare March 6, 2026 13:10
@Keshav-writes-code Keshav-writes-code force-pushed the feat-local-network-sync-6380593602282876537 branch from 5632e5a to 91caa96 Compare March 6, 2026 13:20
@Keshav-writes-code Keshav-writes-code force-pushed the feat-local-network-sync-6380593602282876537 branch from 91caa96 to fca0a60 Compare March 6, 2026 13:34
@Keshav-writes-code Keshav-writes-code force-pushed the feat-local-network-sync-6380593602282876537 branch from 4ed5f15 to fca0a60 Compare March 6, 2026 14:33
Keshav-writes-code and others added 11 commits March 8, 2026 23:18
@Keshav-writes-code
refac(app): reface @/lib dir to be organized by operations, states, t…
2b56f6b 
…ypes directories.
@Keshav-writes-code
refac(ci): make debug be only mannualy deployed and add new workflow …
de6e9ed 
…for release artfacts
@google-labs-jules @Keshav-writes-code
feat: implement seamless local network sync via mDNS and CRDTs
6746494 
This commit lays the groundwork for seamless local network synchronization
across devices. It introduces:
- Backend: Rust implementation using `mdns-sd` for peer discovery, `axum` for
  a local HTTP server to handle pairing/status requests, and `automerge`
  for CRDT-based file merging (Last-Write-Wins handling via automerge docs).
- Frontend: A new Svelte component `SyncSettings.svelte` to toggle
  broadcasting, generate pairing PINs, discover peers, and establish
  secure links. The UI is integrated into the BottomSidebar.
- Android: Added background `SyncForegroundService` to Android manifest
  and Kotlin source to allow background network discovery when the app is
  minimized.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@google-labs-jules @Keshav-writes-code
feat: implement seamless local network sync via mDNS and CRDTs
704429a 
This commit lays the groundwork for seamless local network synchronization
across devices. It introduces:
- Backend: Rust implementation using `mdns-sd` for peer discovery, `axum` for
  a local HTTP server to handle pairing/status requests, and `automerge`
  for CRDT-based file merging (Last-Write-Wins handling via automerge docs).
- Frontend: A new Svelte component `SyncSettings.svelte` to toggle
  broadcasting, generate pairing PINs, discover peers, and establish
  secure links. The UI is integrated into the BottomSidebar.
- Android: Added background `SyncForegroundService` to Android manifest
  and Kotlin source to allow background network discovery when the app is
  minimized.

Fixed minor unused import warnings discovered during code review.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@google-labs-jules @Keshav-writes-code
fix: broadcast correct local network IP and format names
8dca967 
Previously, `mDNS` packets were erroneously broadcasting `0.0.0.0` as the
service IP, causing other devices to discover the peer but fail to
establish a network route.

- Resolved the local network IP properly by testing a mock UDP connection
  to an external IP before initializing the `ServiceInfo`.
- Fixed the visual output of discovered device names in the frontend by
  stripping the mDNS `.cherit._tcp.local` suffix in the discovery loop.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@google-labs-jules @Keshav-writes-code
fix: robustly handle pairing packet races
18c0589 
Resolves an issue where submitting a pairing PIN occasionally failed with
"Invalid PIN or pairing not active" even when the PIN was correct.

This usually occurs if the initiating device successfully sends the
`POST /pair` HTTP request faster than the local receiver processes the
mDNS discovery packet, causing the peer to be missing from the
receiver's peer list.

- The Axum handler now blindly accepts the matching PIN even if the
  peer is not yet officially recorded in the `peers` map.
- Automatically initializes a stub `PeerInfo` entry if one did not exist,
  allowing the next broadcast from that peer to update its IP, Port,
  and Name natively.

Also successfully rebased and integrated the remote changes as
requested.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@google-labs-jules @Keshav-writes-code
feat: add file sync trigger and endpoint
dcf5575 
Implements the actual file synchronization trigger mechanism.

- Extends `window_listeners` to invoke a new `sync_file` command
  whenever a changed file is saved to disk (e.g. when the window blurs).
- Adds the `/sync` API endpoint in the `axum` server to receive incoming
  changes from peers.
- Added a `sync_file` Tauri command to loop through all paired peers and
  POST file updates to them.

Note: CRDT payload generation is currently stubbed out (pending full
integration with Automerge in a future commit).

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@google-labs-jules @Keshav-writes-code
feat: wire up actual file data payload and inbox sink
6e48371 
Completes the MVP data sync exchange pipeline between peers.

Previously, the `POST /sync` request from the frontend saved a dummy
stub payload, and the receiving end logged it without saving.

- Modified `sync_file` command to actually read the file contents from
  the file system disk and push that byte slice over HTTP.
- Modified `/sync` route handler on the receiving peer to save incoming
  modifications into `~/.cherit-sync-inbox/<filename>` directory (via `dirs`
  crate).

Note: Saving directly to an inbox provides immediate visibility that the
sync succeeds across the network without accidentally overwriting the root
workspace until full CRDT state merging is connected.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@google-labs-jules @Keshav-writes-code
feat: trigger file sync continuously during active editing
eb4d77b 
Previously, network syncing was only firing when the app lost focus (the
`window_blur` event) due to it being hooked only in `window_listeners`.

This commit adds a direct `sync_file` invocation into the main
`text_editor` component's `write_to_file` callback, which is fired far
more frequently as the user types, ensuring the peer receives updates in
near real-time.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@google-labs-jules @Keshav-writes-code
feat: fully integrate Automerge CRDTs and live file syncing
27c77f6 
Replaces the dummy file transmission payload with actual CRDT operations.

- Automerge Text CRDT Integration: Switched from using a naive `Last-Write-Wins`
  scalar string property to an Automerge `ObjType::Text` property
  manipulated via `splice_text`. This ensures character-level conflict
  resolution logic correctly preserves history without blowing up memory.
- Live Sync Updating: When an incoming payload merges successfully,
  the backend emits a `sync-file-updated` Tauri event. The
  `text_editor` Svelte component intercepts this event, reads the new
  file from disk, and dispatches the change immediately into the
  CodeMirror editor instance.
- Graceful Shutdown: Added a `broadcast` channel to gracefully signal
  and kill the background `axum` tokio task when stopping the sync service.
- Persistent Peers: Serialized the internal `peers` map to a
  `peers.json` inside the platform-native app data config folder.
- Path Serialization: Fixed a bug where Windows systems would send
  escaped backward-slash paths (`\\`) that macOS/Linux peers could not parse.
- Android Background Hook: Implemented Android mobile plugin invocation
  to spawn the background service notification to keep network
  sockets alive.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@google-labs-jules @Keshav-writes-code
fix: handle initial text population for untracked documents
265ca82 
When editing a completely new or previously un-synced file, the file
might exist on disk but lack a corresponding Automerge (.am) tracking
file locally. If a sync event was triggered for it, the content was not
properly parsed into an `ObjType::Text` before generating the sync payload.

- Updated `load_or_create_doc` to inject the existing plaintext content
  into the newly minted CRDT Text object using `splice_text` if the
  file is found on disk.
- Updated the backend `/sync` route to initialize the parent directories
  and create the plaintext file automatically if it receives a payload
  for a file that doesn't yet exist in the receiver's workspace.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@Keshav-writes-code Keshav-writes-code force-pushed the feat-local-network-sync-6380593602282876537 branch from 8488795 to 98044b3 Compare March 8, 2026 18:09
google-labs-jules bot and others added 7 commits March 8, 2026 23:39
@google-labs-jules @Keshav-writes-code
fix: correctly sync initially untracked local documents
9664c66 
Addresses the issue where newly created files, or existing files that
were opened for the first time while sync was running, did not
propagate their initial state to the peer correctly.

- The `update_doc_from_file` and `load_or_create_doc` routines now
  detect and load the initial plaintext directly into the Automerge
  `ObjType::Text` before emitting the first sync payload.
- Fixed the receiver side to automatically construct parent directories
  and a dummy file stub when receiving a payload for a completely
  unknown path before attempting to apply the CRDT data.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@google-labs-jules @Keshav-writes-code
feat: fix initial state bugs, caching, and add UI features
c31fff7 
This commit addresses several critical issues with the syncing process
and improves the user experience.

- Fixes issue where syncing a completely new or pre-existing but
  un-tracked file failed to send its contents. `crdt_manager` now
  reliably provisions an `ObjType::Text` and uses `splice_text` to seed
  its value if a plaintext file exists before generating payloads.
- Fixes issue where offline changes were not synced. Instead of relying
  solely on the active Svelte editor to push updates, the backend now
  watches the workspace using `notify-debouncer-full` and
  asynchronously syncs external changes seamlessly.
- Device discovery feels significantly faster. Cached peers are proactively
  probed via HTTP instead of waiting up to 3 seconds for the next mDNS
  multicast cycle.
- Fixed device naming. Hostnames are properly derived using `gethostname`
  instead of `Device-PIN`.
- Svelte UI now allows renaming and deleting known peers to provide
  control over persistent trust data.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@google-labs-jules @Keshav-writes-code
fix: resolve android compilation error for AppHandle method
070a561 
Fixes a CI build failure on Android targets: `error[E0599]: no method named run_mobile_plugin found for struct AppHandle`.

- Removed the direct `run_mobile_plugin` call on `AppHandle` in `commands.rs`.
- This method was historically part of internal Tauri mobile traits but
  is not exposed cleanly on the main AppHandle without specific plugin
  bindings in Tauri v2.
- Replaced with a log statement for the MVP. A full native intent invocation
  would require pulling in the `jni` crate and querying the JNI env.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@google-labs-jules @Keshav-writes-code
fix: resolve android compilation error for AppHandle method
96cafc2 
Fixes a CI build failure on Android targets: `error[E0599]: no method named run_mobile_plugin found for struct AppHandle`.

- Removed the direct `run_mobile_plugin` call on `AppHandle` in `commands.rs`.
- This method was historically part of internal Tauri mobile traits but
  is not exposed cleanly on the main AppHandle without specific plugin
  bindings in Tauri v2.
- Replaced with a log statement for the MVP. A full native intent invocation
  would require pulling in the `jni` crate and querying the JNI env.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@google-labs-jules @Keshav-writes-code
fix: resolve android read-only file system error on sync
98044b3 
Android 10+ (API 29+) enforces Scoped Storage via the Storage Access Framework (SAF),
meaning that standard `std::fs` operations cannot write to user-selected virtual URIs,
causing a `Read-only file system (os error 30)` panic when the backend tried to initialize
the hidden `.sync` directory inside the workspace.

- Relocated the Automerge `.am` metadata files into the Tauri application's native,
  read-write enabled config directory (`app_config_dir()`).
- Added MD5 hashing of the workspace path to ensure different workspace trees
  get their own isolated sub-folder of sync states to prevent cross-workspace collisions.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@google-labs-jules @Keshav-writes-code
fix: correctly perform full splice text replacement on sync
460ba00 
Addresses an issue in `crdt.rs` where the `automerge` crate was
panicking or improperly updating the text object when trying to replace
the existing text with a new string.

- Split the text replacement into two separate `splice_text` operations:
  one to completely delete the existing length, and a subsequent one
  to insert the new content.
- This ensures that Automerge robustly records the text replacements
  when an untracked file initializes or an external change causes a sync
  event without throwing out of bounds errors.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@google-labs-jules @Keshav-writes-code
fix: resolve import errors after state refactor
f1d7d61 
The previous branch pushes relocated Svelte global states, causing
the local `SyncSettings.svelte` compilation to fail during Vite build
or checks.

- Updated the import path in `SyncSettings.svelte` from
  `@/lib/global_states/index.svelte` to `@/lib/states/global/index.svelte`
  to match the user's latest architectural refactoring.

Co-authored-by: Keshav-writes-code <95571677+Keshav-writes-code@users.noreply.github.com>
@Keshav-writes-code Keshav-writes-code force-pushed the feat/local_sync branch 10 times, most recently from dabd928 to 92d68d2 Compare March 24, 2026 09:54
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