docs(coding-agent): changelog entries for the chord runtime replacement

Adds packages/chord/CHANGELOG.md (and ships it with the package) and coding-agent's Removed entries.

packages/chord/CHANGELOG.md

@@ -0,0 +1,15 @@
+# Changelog
+
+## [Unreleased]
+
+### Breaking Changes
+
+- Replaced the facet and service runtime with a typed host runtime: contracts (`local`, `remote`, `method`, `opaque`) are runtime values described with TypeBox schemas, objects are served by hosts (`createHost`, `defineFacet`, `defineRegistry`) and reached through handles, and hosts exchange JSON frames over memory, Node IPC, or WebSocket links (`memoryLinkPair`, `ipcLink`, `webSocketLink`, `acceptWebSockets`), with hot reload of plugins. See `docs/tutorial.md` and `docs/guide.md`
+- Removed `defineService`, `createFacetHost`, `createRemoteServiceBinding`, `createStaticFacetLoader`, `combineFacetLoaders`, the remote-service endpoint, provider, error, and wire helpers, and their types. The old `defineFacet`, `Facet`, and `FacetLoader` are replaced by the new runtime's names of the same spelling
+- Removed the `./bundler` export and the facet bundle loaders of `./node`; `./node` now exports the child host manager (`createHostManager`, `forkDriver`, `childControl`, `processLock`) and the facet module loader `nodeLoader`
+- Removed `@earendil-works/pi-client`, `@earendil-works/pi-protocol`, and `@earendil-works/pi-server`, which served only the old runtime; they are no longer released
+
+### Changed
+
+- `replicatedState`, `copyJson`, `isJsonValue`, `Context`, `JsonValue`, `JsonRepresentation`, `Draft`, and the replicated state types keep their names on the root export; `./context` and `./delta` are unchanged, and `./context` also exports the `Context` and `ContextKey` types
+- Depends on `typebox` instead of `esbuild`

packages/chord/package.json

@@ -33,6 +33,7 @@
 		"dist",
 		"docs",
 		"README.md",
+		"CHANGELOG.md",
 		"src/delta/README.md"
 	],
 	"scripts": {

packages/coding-agent/CHANGELOG.md

@@ -30,6 +30,11 @@
 - Fixed codemode blocking the process for seconds to minutes after scripts with many `text()` calls; joining the output items was quadratic ([#10678](https://github.com/earendil-works/pi/issues/10678))
 - Fixed `pi mcp login --help` and the CLI docs describing `--timeout` as only the wait for the browser; it limits the whole sign-in ([#10636](https://github.com/earendil-works/pi/issues/10636))
 
+### Removed
+
+- Removed the unreleased experimental server, client, and plugin stack (`src/experimental`, `src/cli/experimental`) and its source-only `./client` and `./experimental/plugin` exports; none of it was part of the published package. The `@earendil-works/pi-client`, `@earendil-works/pi-protocol`, and `@earendil-works/pi-server` packages it used are removed and no longer released
+- Removed the dependency on `@earendil-works/chord`
+
 ## [1.1.0] - 2026-10-07
 
 ### New Features