feat(durable,chord): publish commits at adoption, address-following watches, synchronous observers

Durable publishes a stored commit inside Storage.commit's adopt: the
telemetry events, its own observers (document watches, conversation
views, task graph, scheduler, waits), and a dispatch of host
subscribeCommits listeners one microtask later, before every wait and
abort the commit triggers. A commit the storage rejects after adoption is
published before the Session fails; a throwing telemetry adapter is
reported as host_error "telemetry" instead of rejecting a durable commit.

Chord's watch listeners take one change object, { value, ops, retired }
({ value } for native watches); retirement is a flag, not an end.
Durable's document watches follow their address, and a task document's
watch ends after its retirement call. New synchronous observers for
adapters: observeDoc, observeConversation, observeTaskGraph; the watches
are built on them. The env file watcher's change type is renamed
FileChange.

packages/durable/test/examples/04-watches.ts

@@ -32,7 +32,7 @@ console.log("watch baseline:", notesWatch.value);
 const busy = Promise.withResolvers<void>();
 const done = Promise.withResolvers<void>();
 let calls = 0;
-notesWatch.start(async (value, ops, _deliveryContext) => {
+notesWatch.start(async ({ value, ops }, _deliveryContext) => {
 	console.log("watch update:", value, JSON.stringify(ops));
 	// The first call stays busy, as a slow consumer would, while three more commits land.
 	if (++calls === 1) await busy.promise;

packages/durable/test/examples/15-real-model.ts

@@ -45,7 +45,7 @@ if (process.env.OPENAI_API_KEY === undefined) {
 		process.stdout.write(text.slice(printed.length));
 		printed = text;
 	};
-	liveWatch.start(async (value) => {
+	liveWatch.start(async ({ value }) => {
 		const block = value?.generation?.message?.content.find((content) => content.type === "text");
 		if (block?.type === "text") printText(block.text);
 	});

packages/durable/test/examples/18-json.ts

@@ -82,14 +82,14 @@ let stop: () => Promise<unknown>;
 if (mode === "events") {
 	const stream = await watchEvents(harness, root.id, context);
 	print(stream.snapshot);
-	stream.start(async (events) => {
+	stream.start(async ({ value: events }) => {
 		for (const event of events) print(event);
 	});
 	stop = () => stream.stop();
 } else {
 	const watch = await root.watch(context);
 	print({ view: watch.value });
-	watch.start(async (_value, ops) => print({ ops }));
+	watch.start(async ({ ops }) => print({ ops }));
 	stop = () => watch.stop();
 }
 

packages/durable/test/examples/20-late-join.ts

@@ -7,7 +7,6 @@ import { Type } from "@earendil-works/pi-ai";
 import { createModels } from "@earendil-works/pi-ai/models";
 import { fauxAssistantMessage, fauxProvider, fauxText, fauxToolCall } from "@earendil-works/pi-ai/providers/faux";
 import {
-	type AgentEvent,
 	createRegistry,
 	defineExtension,
 	defineTool,
@@ -63,7 +62,7 @@ console.log(
 	view.value.entries.map((entry) => entry.kind),
 );
 console.log("view tool slot:", live.tools?.[0]?.status, JSON.stringify(live.tools?.[0]?.output));
-view.start(async (value) => {
+view.start(async ({ value }) => {
 	const slot = (value.docs["pi.live"] as LiveState).tools?.[0];
 	if (slot?.status === "running") console.log("view output now:", JSON.stringify(slot.output));
 });
@@ -75,7 +74,7 @@ console.log(
 	stream.snapshot.tools.map((slot) => `${slot.name} ${slot.status}`),
 );
 let output = stream.snapshot.tools[0]?.output ?? "";
-stream.start(async (events: readonly AgentEvent[]) => {
+stream.start(async ({ value: events }) => {
 	for (const event of events) {
 		if (event.type === "tool_execution_update" && event.output !== undefined) {
 			output =

packages/durable/test/examples/21-subagent-foreground.ts

@@ -114,7 +114,7 @@ const attached = new Set<ConversationId>();
 const attach = async (id: ConversationId, indent: string): Promise<void> => {
 	attached.add(id);
 	const stream = await watchEvents(harness, id, context);
-	stream.start(async (events) => {
+	stream.start(async ({ value: events }) => {
 		for (const event of events) {
 			print(indent, event);
 			if (event.type !== "tool_execution_update") continue;

packages/durable/test/examples/22-subagent-background.ts

@@ -14,7 +14,6 @@ import { createModels } from "@earendil-works/pi-ai/models";
 import { fauxAssistantMessage, fauxProvider, fauxText, fauxToolCall } from "@earendil-works/pi-ai/providers/faux";
 import { openaiProvider } from "@earendil-works/pi-ai/providers/openai";
 import {
-	type AgentEvent,
 	AssistantEntry,
 	type ConversationId,
 	configure,
@@ -285,7 +284,7 @@ function contentText(content: string | readonly { type: string; text?: string }[
 /** Print the main conversation's messages as they are committed. Subagents work in their own conversations. */
 async function follow(harness: Harness, id: ConversationId): Promise<void> {
 	const stream = await watchEvents(harness, id, context);
-	stream.start(async (events: readonly AgentEvent[]) => {
+	stream.start(async ({ value: events }) => {
 		for (const event of events) {
 			if (event.type !== "message_end") continue;
 			const message = event.entry.model?.[0];