Wait for most of a span's relays, with a three second ceiling

e2e/USER_STORIES.md

@@ -1715,9 +1715,8 @@ Acceptance:
   drawn underneath it, and never appears as an item of its own.
 - Every note carries its reply count, including the ones with no replies.
 - Scrolling to the end of the feed loads more rather than asking her to.
-- The feed is one unbroken stretch back from now. A relay that answers a page
+- The feed is one unbroken stretch back from now, so nothing appears below the
-  from further back than the rest have been asked about waits for the feed to
+  end of the list.
-  reach it, so nothing lands below the end of the list.
 - The section fills from the relays that answer. One that takes the connection
   and then says nothing does not hold it empty.
 

e2e/specs/notifications.spec.ts

@@ -508,8 +508,7 @@ test("US-117 read a follow who is in none of your spaces", async ({seed, as}) =>
 })
 
 test("US-117 read a network feed whose relays answer from different depths", async ({seed, as}) => {
-  // What each relay is asked for one page at a time. A relay that fills its page has only covered
+  // A relay that fills its page has covered only as far back as the page reaches.
-  // as far back as the page reaches, so a busy one is what decides how far the feed has got.
   const pageSize = 100
   const recent = "the harbourmaster moved the moorings again"
   const deep = "the old crane was scrapped in the spring"
@@ -528,8 +527,7 @@ test("US-117 read a network feed whose relays answer from different depths", asy
     })
     indexer.follows(user.alice, [user.bob])
 
-    // Bob writes to both, so the feed asks both. His busy relay holds more than one page of the
+    // Bob's busy relay holds a page of the last two hours, his quiet one a week-old note.
-    // last couple of hours; his quiet one holds a single note from a week ago.
     indexer.relayList(user.bob, {read: [outbox.url], write: [outbox.url, indexer.url]})
     outbox.profile(user.bob, {name: "Bob Barker"})
 
@@ -551,12 +549,9 @@ test("US-117 read a network feed whose relays answer from different depths", asy
 
   await expect(network.getByText(recent)).toBeVisible()
 
-  // The quiet relay answered from a week back, which is days below where the busy one has been
+  // A week back is days below where the busy relay has been asked about, so it is held.
-  // asked about. Drawing it would put a note under the end of the list with the whole week
-  // between still missing.
   await expect(network.getByText(deep)).toHaveCount(0)
 
-  // It is held rather than dropped, so the feed hands it over once it has paged back that far.
   await network.locator(".card").last().scrollIntoViewIfNeeded()
 
   await expect(network.getByText(deep)).toBeVisible()

src/app/feeds.ts

@@ -375,11 +375,15 @@ export type FeedLoadState =
 // nothing in it, and the two have to move the window differently.
 export type FeedSpan = {found: number; complete: boolean; exhausted: boolean}
 
-// The share of the relays a span asked that have to answer before it stops waiting on the rest. A
+// How far a span covered is set by its least generous relay, and quiet relays answer first.
-// request otherwise waits on every one of them, and a relay that accepts a socket and then says
+const SPAN_THRESHOLD = 0.8
-// nothing neither answers nor drops. A span is also what releases the events it found, so one
+
-// silent relay leaves the feed empty rather than slow.
+// A relay that accepts a socket and then says nothing neither answers nor drops.
-const SPAN_THRESHOLD = 0.5
+const SPAN_TIMEOUT = 3000
+
+// Aborting a request resolves it with what arrived, the same way closing it does.
+const spanSignal = (signal: AbortSignal) =>
+  AbortSignal.any([signal, AbortSignal.timeout(SPAN_TIMEOUT)])
 
 // Empty spans to walk per trigger. Enough to cross a gap; not enough to reach the end of the
 // history on a single request.
@@ -530,8 +534,7 @@ export const makeFeed = ({
     }
   }
 
-  // The one door into the feed, so that what it renders is one unbroken stretch back from the
+  // The one door into the feed, and anything older than it has reached waits for the window.
-  // anchor: anything older than the feed has reached waits there until the window gets to it.
   const addEvents = (newEvents: TrustedEvent[]) => {
     const ready: TrustedEvent[] = []
 
@@ -599,7 +602,7 @@ export const makeFeed = ({
     const found = await network.get().request({
       relays,
       autoClose: true,
-      signal: controller.signal,
+      signal: spanSignal(controller.signal),
       threshold: SPAN_THRESHOLD,
       filters: filters.map(filter => ({...filter, ...extension})),
       onEvent: countEvent,
@@ -644,10 +647,7 @@ export const makeFeed = ({
       oldest = edge === undefined ? since : Math.min(edge, until - 1)
     }
 
-    // A span reaches further back than it covers. A relay holding few of these authors answers
+    // A span reaches further back than it covers, so its deepest events wait for the window.
-    // a page from days deeper than a busy one does, and rendering that stretch leaves a list
-    // whose bottom is a scatter the window then fills in above — so it waits for the window
-    // like anything else arriving early.
     addEvents(found)
     reach(oldest)
 
@@ -675,8 +675,6 @@ export const makeFeed = ({
     return {found: found.length, complete, exhausted: false}
   }
 
-  // What the repository already holds is a scatter rather than a stretch — an earlier visit's
-  // pages, a reply pulled in as context from weeks back — so it waits for the window too.
   addEvents(relays.flatMap(url => Array.from(getEventsForUrl(url, filters))))
 
   return {
@@ -773,7 +771,7 @@ export const makeCalendarFeed = ({
     const found = await network.get().request({
       relays,
       autoClose: true,
-      signal: controller.signal,
+      signal: spanSignal(controller.signal),
       threshold: SPAN_THRESHOLD,
       filters: [{kinds: [EVENT_TIME], "#D": daysBetween(since, until).map(String)}],
       onEose: () => {