Add ember-test-waiters to markdown rendering pipeline

[jurgenwerk]

Resolves CS-10661.

Problem

The markdown card-reference, Mermaid, and KaTeX rendering runs in async operations kicked off by modifiers and ember-concurrency tasks after the initial render settles, so settled() could not wait for them. The acceptance tests in markdown-file-def-test.gts compensated with manual 10–15s waitFor/waitUntil timeouts, making them slow and flaky.

Approach

Base card defs run in the card sandbox and cannot import @ember/test-waiters directly — they go through runtime-common's injected waiters (the host test setup calls useTestWaiters, and externals.ts shims @cardstack/runtime-common to that same instance for card modules).

• packages/runtime-common/test-waiters.ts (new) — extracts the waiter-injection plumbing out of fetcher.ts into a shared module exposing a lazy buildWaiter(label) and waitForPromise(). No-op in production; backs onto the real @ember/test-waiters once the host injects. Lazy resolution lets a module build its waiter at import time, before injection.
• packages/runtime-common/fetcher.ts — refactored to consume the shared module (buildWaiter('fetcher')); behaviour unchanged.
• packages/base/default-templates/markdown.gts — registers a markdown-rendering waiter around:
  • _loadKatexTask and _renderMermaidTask (begin/end around the async body)
  • the deferred card-slot collection (beginAsync when scheduleOnce('afterRender') is queued, endAsync in the updateSlots finally), plus a teardown guard so a destroyed modifier can't leave settled() hanging.
• packages/host/tests/acceptance/markdown-file-def-test.gts — removes the manual waitFor/waitUntil timeouts (7× @10s + 4× @15s) and relies on settled(). The overlay cursor:pointer binding and URL-bar navigation now resolve naturally via the slot waiter.

Testing

ember test --filter "markdown" → 206/206 pass; the BFM module re-run 3× with no flakes. The instrumented acceptance tests now complete in ~0.7–1.5s each (Mermaid 715ms, KaTeX 715ms, card refs 1445ms) instead of being gated by the 10–15s ceilings.

Out of scope

The one remaining waitUntil (5s) in captureFileExtractResult waits on the prerender file-extract pipeline — a separate subsystem the three instrumented operations don't cover.

🤖 Generated with Claude Code

[github-actions]

Preview deployments

• Host staging preview

• Host production preview

Host Test Results

    1 files  ± 0      1 suites  ±0   1h 52m 33s ⏱️ + 2m 59s
2 917 tests +45  2 902 ✅ +45  15 💤 ±0  0 ❌ ±0 
2 936 runs  +45  2 921 ✅ +45  15 💤 ±0  0 ❌ ±0 

Results for commit 3b559cc. ± Comparison against earlier commit 0eb55bc.

Realm Server Test Results

    1 files  ±    0      1 suites  ±0   10m 16s ⏱️ + 1m 8s
1 547 tests +   10  1 546 ✅ +   10  1 💤 ±0  0 ❌ ±0 
2 804 runs  +1 176  2 802 ✅ +1 175  2 💤 +1  0 ❌ ±0 

Results for commit 3b559cc. ± Comparison against earlier commit 0eb55bc.

[Copilot]

Pull request overview

This PR instruments the markdown rendering pipeline (card references, Mermaid, KaTeX, and deferred slot collection) with Ember test waiters so settled() correctly waits for post-render async work, eliminating slow/flaky manual timeouts in acceptance tests.

Changes:

• Introduces a sandbox-safe waiter plumbing module in runtime-common and refactors fetcher to use it.
• Wraps markdown async rendering work in a markdown-rendering waiter so acceptance tests can rely on settled().
• Fixes CI report artifact naming so re-run attempts don’t merge stale shard results into the published “Host Test Results” check.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
packages/runtime-common/test-waiters.ts	New shared waiter injection + lazy waiter helpers for sandboxed code.
packages/runtime-common/index.ts	Re-exports the new test-waiters module from the package entrypoint.
packages/runtime-common/fetcher.ts	Switches fetcher waiters to the shared waiter plumbing.
packages/base/default-templates/markdown.gts	Adds a markdown-rendering waiter around Mermaid/KaTeX tasks and deferred slot collection.
packages/host/tests/acceptance/markdown-file-def-test.gts	Removes manual waitFor/waitUntil timeouts in favor of settled().
packages/host/tests/unit/services/render-service-test.ts	Adds afterEach cleanup to unregister globally-registered card-reference prefix mappings.
.github/workflows/ci-host.yaml	Scopes junit artifact names/patterns to github.run_attempt to avoid stale merges on re-run.

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[github-actions]

Observability diff (vs staging)

Show diff

diff --git a/tmp/remote-canon.sMR0tB/dashboards/boxel-status/service-prerender-manager.json b/tmp/committed-canon.TJsdsN/dashboards/boxel-status/service-prerender-manager.json
index 517ba1c..c4fbf99 100644
--- a/tmp/remote-canon.sMR0tB/dashboards/boxel-status/service-prerender-manager.json
+++ b/tmp/committed-canon.TJsdsN/dashboards/boxel-status/service-prerender-manager.json
@@ -2618,7 +2618,7 @@
         {
           "hide": 2,
           "name": "env",
-          "query": "staging",
+          "query": "__ENV__",
           "skipUrlSync": true,
           "type": "constant"
         },

(Run: https://github.com/cardstack/boxel/actions/runs/26871295567)