experimentally enable subduction in browser tab

.changeset/subduction-forty-eight.md

@@ -0,0 +1,8 @@
+---
+"@inkandswitch/patchwork-bootloader": patch
+"@inkandswitch/patchwork-filesystem": patch
+"@inkandswitch/patchwork": patch
+"@inkandswitch/patchwork-plugins": patch
+---
+
+`@automerge/automerge` goes to `3.4.1`, and `@automerge/automerge-repo-network-broadcastchannel` joins the automerge-repo family at `2.6.0-subduction.48`.

.changeset/tab-worker-subduction.md

@@ -0,0 +1,20 @@
+---
+"@inkandswitch/patchwork-bootloader": minor
+"@inkandswitch/patchwork": minor
+---
+
+Every Repo on the origin is its own Subduction node. A tab holds this origin's IndexedDB, keeps its own WebSocket to the sync server, and meets the other tabs over a BroadcastChannel carrying Subduction (`siblingAdapters()` in `@inkandswitch/patchwork-bootloader/siblings`, passed to `new Repo({ subductionAdapters })`). The automerge SharedWorker no longer sits between tabs and storage — it is one more such node, kept only to resolve `automerge:` URLs for the service worker, which can't own a Repo itself. The websocket proxy worker is gone with it.
+
+Benchmarked against the shared-worker arrangement (`sites/bench`): boot and memory are a wash or better, cross-tab propagation matches, and two shared-worker failures go away — a `find()` racing a sibling's `create()` settled as unavailable, and edits made just before a tab closed were lost, since a storageless tab had nothing to flush to. Each tab flushing its own IndexedDB closes both.
+
+Keyhive sites use the subduction-backed hive in both the tab and the worker, each talking to the sync server directly.
+
+`patchwork.sw.subscribeSyncState(documentId, listener)` stays, now a filter over the tab's own Repo's `subduction-remote-heads` event, replaying the server's current heads from `handle.getSyncInfo()` on subscribe; `SyncStateDocMessage` is exported from `@inkandswitch/patchwork`. Removed from `setupServiceWorker()`'s result: `subscribeToRepoChannel`, `getRepoChannel`, `subscribeSyncState`. The `@patchwork/syncstate` BroadcastChannel and the other `SyncState*` message types are gone too; a tab's own Repo has what they carried — `repo.isSubductionConnected()` and the `subduction-connection` event for the link, `repo.connectedSubductionPeerIds()` for which peers are the server, and `patchwork.signerIdentity` for this tab's peer id. `createRepo` in `@inkandswitch/patchwork` takes no arguments.
+
+`@inkandswitch/patchwork-bootloader` depends on `@automerge/automerge-repo-network-broadcastchannel`, which is also on the importmap.
+
+That worker is renamed for what it now does: `@inkandswitch/patchwork-bootloader/automerge-worker` is now `@inkandswitch/patchwork-bootloader/automerge-protocol-handler-worker`, emitted as `automerge-protocol-handler-worker.js` (the `workerPath` option on `setupServiceWorker` still overrides it), and `getAutomergeWorker()` is now `getAutomergeProtocolHandlerWorker()`.
+
+Inter-tab sync is Subduction, not classic automerge sync. `connectSiblings(repo, hive)` is replaced by `siblingAdapters()`, which returns the `subductionAdapters` entries for a Repo rather than mutating one after the fact, so it is passed to the `Repo` constructor. The frames on the siblings BroadcastChannel are Subduction transport frames authenticated by each node's own signer; the keyhive network adapter no longer wraps that channel, since keyhive material reaches siblings the same way it reaches the sync server. The one remaining classic-sync path is the opt-in classic sync server the protocol handler worker connects to on request.
+
+Subduction's handshake has an initiator and a responder, and a BroadcastChannel is a mesh, so the siblings adapter is passed with `role: "mesh"`, added to the automerge-repo fork's `subductionAdapters` by this repo's pnpm patch: for each pair of peers on the adapter, the one whose peer id sorts lower initiates the handshake and the other accepts.

core/bootloader/package.json

@@ -26,6 +26,10 @@
       "import": "./dist/externals-list.js",
       "types": "./dist/externals-list.d.ts"
     },
+    "./siblings": {
+      "import": "./dist/siblings.js",
+      "types": "./dist/siblings.d.ts"
+    },
     "./storage": {
       "import": "./dist/storage.js",
       "types": "./dist/storage.d.ts"
@@ -34,9 +38,9 @@
       "import": "./dist/service-worker.js",
       "types": "./dist/service-worker.d.ts"
     },
-    "./automerge-worker": {
-      "import": "./dist/automerge-worker.js",
-      "types": "./dist/automerge-worker.d.ts"
+    "./automerge-protocol-handler-worker": {
+      "import": "./dist/automerge-protocol-handler-worker.js",
+      "types": "./dist/automerge-protocol-handler-worker.d.ts"
     },
     "./module-loader": {
       "import": "./dist/module-loader.js",
@@ -56,6 +60,7 @@
     "@automerge/automerge": "catalog:",
     "@automerge/automerge-repo": "catalog:",
     "@automerge/automerge-repo-keyhive": "catalog:",
+    "@automerge/automerge-repo-network-broadcastchannel": "catalog:",
     "@automerge/automerge-repo-network-messagechannel": "catalog:",
     "@automerge/automerge-repo-network-websocket": "catalog:",
     "@automerge/automerge-repo-storage-indexeddb": "catalog:",