@W-17388345 - add context support to ssrv2 component lifecycle #5387

jhefferman-sfdc · 2025-06-13T14:56:22Z

Details

Add SSRv2 context support to the component lifecycle. It has already been added for SSRv2 / CSR so now state-managers can function without additional shims and extending non-lightning components.

Does this pull request introduce a breaking change?

😮‍💨 No, it does not introduce a breaking change.

Does this pull request introduce an observable change?

🤞 No, it does not introduce an observable change.

GUS work item

W-17388345

wjhsf · 2025-06-13T16:56:12Z

packages/@lwc/engine-server/src/__tests__/fixtures.spec.ts

+        (global as any).trustedContext = trustedContext;
+        (global as any).connectContext = connectContext;
+        (global as any).disconnectContext = disconnectContext;


Gross. Can we at least call them __testTrustedContext or something, so it's more clear elsewhere what they're for?

Can these be setup as a singleton and then imported from the spec files? Seems like this works just fine, so that's not a problem. But importing a singleton would be less surprising in the future when we forget what this stuff is, and compared to seeing a reference and trying to remember what it is and how it works.

I don't love the globals either. In theory we could do imports but is there precedence for this? If we introduce logging (align V1/V2 error handling so they both log instead of V2 throwing) then we could do away with these fixtures and have cleaner hydration tests. Using a different naming complicates things as they are symbols. I'll bring this up next parking lot and fix this in a follow up depending on what we decide if that is ok.

wjhsf · 2025-06-13T17:00:04Z

packages/@lwc/ssr-runtime/src/index.ts

 } from '@lwc/shared';

+export { setFeatureFlag, setFeatureFlagForTest } from '@lwc/features';


Add @lwc/features as a dev dependency so that it gets properly bundled.

wjhsf · 2025-06-13T17:01:06Z

packages/@lwc/ssr-runtime/src/context.ts

+            (le as any)[contextfulKeys[i]][connectContext](new ContextBinding(le));
+        }
+    } catch (err: any) {
+        if (process.env.NODE_ENV !== 'production') {


Why do we ignore errors in production?

It is similar to the above where we conditionally show an error in dev/test. But because this is at the end of a function, we don't need an early-return the way we do in the other instance.

wjhsf · 2025-06-13T17:08:38Z

...es/@lwc/engine-server/src/__tests__/fixtures/context-binding/duplicate-context/error-ssr.txt

@@ -0,0 +1 @@
+Attempted to connect to trusted context but received the following error: Multiple contexts of the same variety were provided.


Why is SSR v2 an error, but engine-server not?

we don't have the concept of logging in SSRv2 runtime (from what I can tell - feel free to correct me). I didn't feel it necessary to introduce that now, simply wrapping in !production felt adequate. However if either/both of you disagree, i'd be happy to introduce logging (not throwing) in a follow up PR (it will reduce the amount of testing needed).

wjhsf · 2025-06-13T17:10:52Z

...ests__/fixtures/context-binding/duplicate-context/modules/x/contextManager/contextManager.js

+
+export const defineContext = (fromContext) => {
+    const contextDefinition = (initialValue) =>
+        new MockContextSignal(initialValue, contextDefinition, fromContext);


Wait, it provides itself as a param? Trippy...

wjhsf · 2025-06-13T17:11:34Z

packages/@lwc/integration-karma/scripts/karma-plugins/hydration-tests.js

@@ -279,12 +279,6 @@ function createHCONFIG2JSPreprocessor(config, logger, emitter) {
            const location = path.relative(basePath, filePath);
            log.error('Error processing “%s”\n\n%s\n', location, error.stack || error.message);
            done(error, null);
-        } finally {


Why is this block deleted?

It was redundant (mistake from the past)

divmain

Approval, modulo a couple of minor changes. No need for a re-review if you address the feedback and GitHub still gives you the green button. If you need another approval after making changes, please ping me.

divmain · 2025-06-13T17:53:53Z

packages/@lwc/engine-server/src/__tests__/fixtures.spec.ts

+        (global as any).trustedContext = trustedContext;
+        (global as any).connectContext = connectContext;
+        (global as any).disconnectContext = disconnectContext;


Can these be setup as a singleton and then imported from the spec files? Seems like this works just fine, so that's not a problem. But importing a singleton would be less surprising in the future when we forget what this stuff is, and compared to seeing a reference and trying to remember what it is and how it works.

divmain · 2025-06-13T17:57:41Z

packages/@lwc/integration-karma/test-hydration/context/x/main/main.js

@@ -2,7 +2,8 @@ import { LightningElement, api } from 'lwc';
 import { defineMalformedContext } from 'x/contextManager';
 export default class Root extends LightningElement {
    @api showTree = false;
-    malformedContext = defineMalformedContext()();
+    // Only test in CSR right now as SSR throws which prevents content from being rendered. There is additional fixtures ssr coverage for this case.
+    malformedContext = typeof window !== 'undefined' ? defineMalformedContext()() : undefined;


Thanks for leaving this comment.

divmain · 2025-06-13T18:00:23Z

packages/@lwc/ssr-compiler/src/__tests__/fixtures.spec.ts

+        setTrustedContextSet(trustedContext);
+        (global as any).trustedContext = trustedContext;
+        (global as any).connectContext = connectContext;
+        (global as any).disconnectContext = disconnectContext;


Oh I see you're overwriting these global objects here. This gets extra confusing. If the globals were moved into a separate module as a singleton, and if that module also exported setTrustedContext and similar functions, that would be preferred. Unless there's a reason this must be setup using globals, in which case let's find a place to document the reasoning.

divmain · 2025-06-13T18:01:11Z

packages/@lwc/ssr-runtime/src/context.ts

+        if (contextVarieties.has(contextVariety)) {
+            if (process.env.NODE_ENV !== 'production') {
+                throw new Error('Multiple contexts of the same variety were provided.');
+            }


This is a nice ergonomic touch; thank you.

divmain · 2025-06-13T18:01:48Z

packages/@lwc/ssr-runtime/src/context.ts

+        this.component = component;
+    }
+
+    provideContext<V extends object>(


I know these methods are documented elsewhere, perhaps in the CSR implementation, but it'd be nice to have doc strings for these methods here as well.

divmain · 2025-06-13T18:03:58Z

packages/@lwc/ssr-runtime/src/context.ts

+            (le as any)[contextfulKeys[i]][connectContext](new ContextBinding(le));
+        }
+    } catch (err: any) {
+        if (process.env.NODE_ENV !== 'production') {


It is similar to the above where we conditionally show an error in dev/test. But because this is at the end of a function, we don't need an early-return the way we do in the other instance.

divmain · 2025-06-13T18:04:43Z

packages/@lwc/ssr-runtime/src/lightning-element.ts

+        if (lwcRuntimeFlags.ENABLE_EXPERIMENTAL_SIGNALS) {
+            // Setup context before connected callback is executed
+            connectContext(this);
+        }


This is wonderfully straightforward :)

jhefferman-sfdc · 2025-06-14T03:16:33Z

@divmain @wjhsf thank you both for your reviews - unfortunately there were other issues with the fixtures test in addition to the ugly global assignments. Due to disparities in dev/production runs of vitest and how the thrown Errors are handled the CI cannot pass. I've added some basic unit coverage and removed the fixtures coverage for now. I created a separate work item to review the coverage and make sure it's adequate: W-18783313

jhefferman-sfdc added 2 commits June 11, 2025 11:16

feat: add context support to v2

cfb5f7d

feat: ssrv2 context

719a6e9

jhefferman-sfdc requested a review from a team as a code owner June 13, 2025 14:56

jhefferman-sfdc and others added 2 commits June 13, 2025 08:57

feat: test coverage

a807713

Merge branch 'master' into jhefferman/context-ssrv2

bd16f3e

wjhsf reviewed Jun 13, 2025

View reviewed changes

divmain approved these changes Jun 13, 2025

View reviewed changes

jhefferman-sfdc added 3 commits June 13, 2025 20:46

fix: prod test run

53bc835

fix: prod test run

3efd32a

fix temp removal of fixtures coverage due to production failure

dce0888

jhefferman-sfdc added 5 commits June 13, 2025 21:17

fix: prettier

7385cc2

fix: add vitest coverage

af1465d

fix: add vitest coverage

f4e6b89

fix: update ssr-runtime README with new functions

24fba78

Merge branch 'master' into jhefferman/context-ssrv2

32af684

jhefferman-sfdc enabled auto-merge (squash) June 14, 2025 04:16

jhefferman-sfdc merged commit 446e23b into master Jun 14, 2025
6 checks passed

jhefferman-sfdc deleted the jhefferman/context-ssrv2 branch June 14, 2025 04:23

		} from '@lwc/shared';

		export { setFeatureFlag, setFeatureFlagForTest } from '@lwc/features';

		@@ -0,0 +1 @@
		Attempted to connect to trusted context but received the following error: Multiple contexts of the same variety were provided.

@W-17388345 - add context support to ssrv2 component lifecycle #5387

@W-17388345 - add context support to ssrv2 component lifecycle #5387

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jhefferman-sfdc commented Jun 13, 2025

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Does this pull request introduce a breaking change?

Does this pull request introduce an observable change?

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