Recreate the zooid container in teardown and let its network churn settle

e2e/ARCHITECTURE.md

@@ -389,6 +389,18 @@ and refreshed on the way up — zooid saves a relay's toml back when a NIP-86 ca
 every test starts against the same relays with nothing in them. The container is a worker fixture,
 so the docker start-up cost is paid once per worker rather than once per test.
 
+It is recreated in the teardown of the test that finishes, not the setup of the one that starts.
+Creating a container tears down a veth pair and builds another, and the bridge behind it loses
+carrier with them; chromium watches the host's interfaces and aborts everything it has in flight
+when they move, which the app meets as a route chunk that failed to import and, with `ssr = false`,
+a 500 page.
+Recreating from teardown puts the next test's seeding — an authenticated socket per identity, and
+every fixture written over it — between the churn and the first page that test opens. That is not
+on its own enough: every netlink event lands before `compose up --wait` returns, but chromium
+coalesces interface changes for up to two seconds before acting on one. So a recreate also stamps
+the moment it settles, and a page waits out whatever is left of that window when it opens — which
+for most tests is nothing, the teardown and the seeding having spent it already.
+
 Seeding then writes over a real authenticated socket, one per identity per relay, held open for the
 rest of the test. A fixture must therefore be signed by an identity `harness/keys.ts` holds, since
 zooid authenticates every write.

e2e/harness/index.ts

@@ -172,8 +172,8 @@ export const test = base.extend<HarnessFixtures, HarnessWorkerFixtures>({
         "them. Anything the app fetches belongs in a mock installed by `as(user, path)`.",
     )
   },
-  // One container per worker, torn down when the worker ends. It is reset between tests rather
-  // than recreated, so the docker start-up cost is paid once.
+  // One container per worker, torn down when the worker ends. It is recreated between tests, in
+  // the teardown of the test that finishes rather than the setup of the one that starts.
   zooid: [
     // playwright reads a fixture's dependencies off this pattern, so it has to stay a pattern
     // even when there are none.
@@ -192,7 +192,7 @@ export const test = base.extend<HarnessFixtures, HarnessWorkerFixtures>({
     testInfo.skip(Boolean(dockerProblem), dockerProblem)
 
     await zooid.start()
-    await zooid.reset()
+    await zooid.ensure()
 
     const contexts: BrowserContext[] = []
     const faults = watchFaults()
@@ -207,6 +207,8 @@ export const test = base.extend<HarnessFixtures, HarnessWorkerFixtures>({
 
     const open = async (path: string, options: PageOptions, user?: TestUser) => {
       const {urls, indexerUrls, cache} = requireScenario()
+
+      await zooid.settle()
       // The project's own `use` first, so a viewport or device descriptor set in
       // playwright.config.ts reaches the context rather than being dropped.
       //
@@ -291,6 +293,11 @@ export const test = base.extend<HarnessFixtures, HarnessWorkerFixtures>({
       await context.close()
     }
 
+    // Before the assertions below, which throw: a test that fails still owes the next one a
+    // container, and with every page already closed there is nothing left for the recreate's
+    // network churn to interrupt.
+    await zooid.reset()
+
     if (faults.found.length > 0 || testInfo.status !== testInfo.expectedStatus) {
       // A path rather than a body: the list reporter truncates an inline attachment, and the
       // nightly run on the box keeps test-results and nothing else.

e2e/harness/zooid/relay.ts

@@ -22,6 +22,12 @@ import type {ZooidConnection} from "./transport"
 
 const image = "gitea.coracle.social/coracle/zooid:latest"
 
+// How long after a recreate chromium can still abort what a page has in flight. Every netlink
+// event a create-and-destroy produces lands before `compose up --wait` returns — measured at 26 of
+// them, all of them within a second, none after — but chromium coalesces interface changes for up
+// to two seconds before acting on one, so the abort arrives well after the harness has moved on.
+const SETTLE = 2500
+
 const composeFile = fileURLToPath(new URL("docker/compose.yaml", import.meta.url))
 
 const configSource = fileURLToPath(new URL("docker/config", import.meta.url))
@@ -167,6 +173,12 @@ export class Zooid {
 
   private started = false
 
+  // Whether a container is up. `reset` is what creates one, so this stays false until it has run.
+  private running = false
+
+  // When the last recreate's interface churn stops being able to abort a request.
+  private settledAt = 0
+
   // Verifies docker rather than bringing the container up, which `reset` does. Repeat calls are
   // free, so the fixture can call this per test.
   start = async () => {
@@ -226,10 +238,36 @@ export class Zooid {
     }
   }
 
+  // Leaves a fresh container for whoever runs next. Recreating one churns the host's network
+  // interfaces — a veth pair torn down and rebuilt, the project's bridge losing carrier with it —
+  // and chromium aborts every request it has in flight when it acts on that, which reaches the app
+  // as a route chunk that failed to import and, with `ssr = false`, a 500 page. So this is called
+  // from teardown rather than setup, and everything after it counts towards `settle` below.
   reset = async () => {
     this.closeSessions()
 
     await this.up()
+
+    this.running = true
+    this.settledAt = Date.now() + SETTLE
+  }
+
+  // The container the test about to run will use. Only the first test of a worker finds none.
+  ensure = async () => {
+    if (!this.running) {
+      await this.reset()
+    }
+  }
+
+  // Waited out before a page is opened, which is as late as it can be left: teardown, the next
+  // test's fixtures and its seeding are all inside the window already, so most tests pay nothing
+  // here.
+  settle = async () => {
+    const remaining = this.settledAt - Date.now()
+
+    if (remaining > 0) {
+      await sleep(remaining)
+    }
   }
 
   stop = async () => {
@@ -239,6 +277,7 @@ export class Zooid {
       await compose("down")
 
       this.started = false
+      this.running = false
     }
   }