[zach-klippenstein]

Stacked on #1588, which should merge first. After rebasing, the cached renderContext from #1588 stays as it is when the workflow instance changes: RenderContext(this, interceptedWorkflow) only uses the workflow argument for type inference and wraps nothing but this. The benchmark comparison in the comments was measured against main, before this rebase.

Fixes a finding from review of #1442 (comment).

ComposeRenderContext is remembered per workflow identity, but it kept the first workflow and interceptedWorkflow it was created with. When a parent rendered a new instance of the same workflow type and key, the compose runtime still called render, onPropsChanged and snapshotState on the old instance, so it could hold on to stale constructor dependencies. The legacy runtime (StatefulWorkflowNode.maybeUpdateCachedWorkflowInstance()) switches to the new instance, re-intercepts it, and keeps the session's state.

Tests (first commit)

Added to RenderWorkflowInTest. In each one, the parent renders a new child instance on every render pass:

• new_child_workflow_instance_is_used_to_render_without_resetting_state (ported from Add tests for Compose runtime review feedback [CLF-524] #1577): render uses the new instance, and the child keeps its state.
• new_child_workflow_instance_is_used_for_onPropsChanged: onPropsChanged is called on the new instance.
• new_child_workflow_instance_is_used_for_snapshotState: a snapshot saved after the instance changed was written by the new instance.
• interceptor_renders_new_child_workflow_instance: an interceptor's proceed renders the new instance.

Before the fix, all 4 failed on COMPOSE_RUNTIME_NON_SKIPPING and COMPOSE_RUNTIME_SKIPPING (for example expected:<v[1] props=1 state=1> but was:<v[0] props=1 state=1>), and passed on all 64 legacy runtime configs.

Fix (second commit)

renderWorkflow now calls ComposeRenderContext.updateWorkflow(workflow) on every pass. If the instance changed (identity check), it stores the new instance and re-intercepts it. Session state is left alone. The call happens before the skip check, so a child that skips this pass still uses the new instance for its next render and its snapshots.

With the fix, all :workflow-runtime:jvmTest tests pass.

🤖 Generated with Claude Code

[zach-klippenstein]

🤖 Compose runtime microbenchmarks, main (0cf0569) vs this branch (0b4d885)

I ran :benchmarks:runtime-microbenchmark:connectedReleaseAndroidTest on a Galaxy A25 (SM-A256U1, Android 16), plugged in, thermal status 0. Only the 4 compose classes ran ({ShallowBushyTree, SquareishTree} × {ComposeNoSkip, ComposeSkipping}), so there's no AllOptimizations control group in this run. Each branch got one back-to-back run, main first.

Allocations: unchanged in every benchmark. The ±1 differences are median noise. The fix adds an identity check per child render and allocates only when the instance actually changes, which none of these benchmarks do.

Time: geometric mean of branch/main median time.

Config	Geomean Δ time	Range
ShallowBushyTree_ComposeNoSkip	-0.7%	-6.5% … +8.2%
ShallowBushyTree_ComposeSkipping	+0.7%	-1.9% … +2.9%
SquareishTree_ComposeNoSkip	+0.8%	-4.4% … +5.1%
SquareishTree_ComposeSkipping	+3.3%	-2.1% … +10.6%
All	+1.0%

Deltas go both ways within each config. SquareishTree_ComposeSkipping leans slower. Allocations are identical, and there's no control group to show whether the phone drifted between the two runs, so I can't tell that apart from noise in a single run.

Full results (median time and allocation count)

Config	Benchmark	main time (ms)	branch time (ms)	Δ time	main allocs	branch allocs	Δ allocs
ShallowBushyTree_ComposeNoSkip	initialRenderAllChildren	2.230	2.236	+0.3%	10864	10863	-0.0%
ShallowBushyTree_ComposeNoSkip	initialRenderNewSibling	0.741	0.725	-2.1%	2582	2582	+0.0%
ShallowBushyTree_ComposeNoSkip	rememberManyEntries_changingInputs	0.503	0.496	-1.3%	2865	2865	-0.0%
ShallowBushyTree_ComposeNoSkip	rememberManyEntries_mixedInputTypes	0.542	0.550	+1.5%	3241	3241	+0.0%
ShallowBushyTree_ComposeNoSkip	rememberManyEntries_sameInputs	0.419	0.414	-1.0%	2733	2733	+0.0%
ShallowBushyTree_ComposeNoSkip	rerenderAllChildrenByPropsChange	0.587	0.635	+8.1%	1931	1931	-0.0%
ShallowBushyTree_ComposeNoSkip	rerenderAllChildrenViaStateChange	0.530	0.524	-1.1%	1828	1828	-0.0%
ShallowBushyTree_ComposeNoSkip	rerenderSingleSiblingByPropsChange	0.500	0.503	+0.6%	1914	1914	+0.0%
ShallowBushyTree_ComposeNoSkip	rerenderSingleSiblingViaStateChange	0.472	0.472	+0.0%	1820	1820	-0.0%
ShallowBushyTree_ComposeNoSkip	stableHandlers_manyCallbacks_propChange	0.406	0.411	+1.2%	2733	2733	+0.0%
ShallowBushyTree_ComposeNoSkip	tearDownAllChildren	1.699	1.589	-6.5%	5036	5036	+0.0%
ShallowBushyTree_ComposeNoSkip	tearDownSingleSibling	1.304	1.304	+0.1%	2674	2674	-0.0%
ShallowBushyTree_ComposeNoSkip	wideSiblingKeys_initialRenderAllChildren	3.333	3.215	-3.6%	15855	15855	+0.0%
ShallowBushyTree_ComposeNoSkip	wideSiblingKeys_rerenderSingleSiblingByPropsChange	0.586	0.557	-4.9%	1533	1533	+0.0%
ShallowBushyTree_ComposeSkipping	initialRenderAllChildren	2.420	2.402	-0.8%	11619	11620	+0.0%
ShallowBushyTree_ComposeSkipping	initialRenderNewSibling	0.533	0.534	+0.2%	1190	1190	+0.0%
ShallowBushyTree_ComposeSkipping	rememberManyEntries_changingInputs	0.501	0.511	+2.1%	2867	2867	-0.0%
ShallowBushyTree_ComposeSkipping	rememberManyEntries_mixedInputTypes	0.553	0.548	-0.8%	3243	3243	-0.0%
ShallowBushyTree_ComposeSkipping	rememberManyEntries_sameInputs	0.443	0.444	+0.3%	2743	2743	-0.0%
ShallowBushyTree_ComposeSkipping	rerenderAllChildrenByPropsChange	0.667	0.679	+1.8%	2085	2085	+0.0%
ShallowBushyTree_ComposeSkipping	rerenderAllChildrenViaStateChange	0.639	0.652	+2.0%	2063	2063	+0.0%
ShallowBushyTree_ComposeSkipping	rerenderSingleSiblingByPropsChange	0.288	0.286	-0.9%	514	514	+0.0%
ShallowBushyTree_ComposeSkipping	rerenderSingleSiblingViaStateChange	0.251	0.257	+2.2%	423	423	+0.0%
ShallowBushyTree_ComposeSkipping	stableHandlers_manyCallbacks_propChange	0.431	0.435	+0.9%	2743	2743	+0.0%
ShallowBushyTree_ComposeSkipping	tearDownAllChildren	1.820	1.827	+0.4%	5041	5041	+0.0%
ShallowBushyTree_ComposeSkipping	tearDownSingleSibling	1.162	1.180	+1.5%	1275	1275	-0.0%
ShallowBushyTree_ComposeSkipping	wideSiblingKeys_initialRenderAllChildren	4.766	4.675	-1.9%	18358	18359	+0.0%
ShallowBushyTree_ComposeSkipping	wideSiblingKeys_rerenderSingleSiblingByPropsChange	0.655	0.674	+3.0%	1296	1296	-0.0%
SquareishTree_ComposeNoSkip	initialRenderAllChildren	10.707	10.512	-1.8%	40446	40446	+0.0%
SquareishTree_ComposeNoSkip	initialRenderNewSibling	2.562	2.615	+2.1%	8586	8586	+0.0%
SquareishTree_ComposeNoSkip	rememberManyEntries_changingInputs	0.504	0.528	+4.8%	2865	2865	+0.0%
SquareishTree_ComposeNoSkip	rememberManyEntries_mixedInputTypes	0.554	0.535	-3.5%	3241	3241	-0.0%
SquareishTree_ComposeNoSkip	rememberManyEntries_sameInputs	0.427	0.428	+0.3%	2733	2733	+0.0%
SquareishTree_ComposeNoSkip	rerenderAllChildrenByPropsChange	2.556	2.655	+3.9%	8453	8453	-0.0%
SquareishTree_ComposeNoSkip	rerenderAllChildrenViaStateChange	2.311	2.320	+0.4%	8344	8344	-0.0%
SquareishTree_ComposeNoSkip	rerenderSingleSiblingByPropsChange	2.361	2.353	-0.3%	8446	8447	+0.0%
SquareishTree_ComposeNoSkip	rerenderSingleSiblingViaStateChange	2.141	2.129	-0.6%	8331	8331	-0.0%
SquareishTree_ComposeNoSkip	stableHandlers_manyCallbacks_propChange	0.418	0.422	+1.0%	2733	2733	-0.0%
SquareishTree_ComposeNoSkip	tearDownAllChildren	6.895	7.017	+1.8%	25351	25350	-0.0%
SquareishTree_ComposeNoSkip	tearDownSingleSibling	2.664	2.799	+5.1%	8535	8536	+0.0%
SquareishTree_ComposeNoSkip	wideSiblingKeys_initialRenderAllChildren	3.216	3.321	+3.3%	15855	15855	-0.0%
SquareishTree_ComposeNoSkip	wideSiblingKeys_rerenderSingleSiblingByPropsChange	0.617	0.590	-4.4%	1533	1533	+0.0%
SquareishTree_ComposeSkipping	initialRenderAllChildren	11.427	11.719	+2.6%	43122	43122	-0.0%
SquareishTree_ComposeSkipping	initialRenderNewSibling	1.941	1.977	+1.9%	4243	4244	+0.0%
SquareishTree_ComposeSkipping	rememberManyEntries_changingInputs	0.520	0.521	+0.2%	2867	2867	-0.0%
SquareishTree_ComposeSkipping	rememberManyEntries_mixedInputTypes	0.558	0.602	+7.8%	3243	3243	+0.0%
SquareishTree_ComposeSkipping	rememberManyEntries_sameInputs	0.446	0.465	+4.3%	2743	2743	-0.0%
SquareishTree_ComposeSkipping	rerenderAllChildrenByPropsChange	3.081	3.196	+3.7%	9184	9184	-0.0%
SquareishTree_ComposeSkipping	rerenderAllChildrenViaStateChange	2.950	2.963	+0.4%	9444	9444	-0.0%
SquareishTree_ComposeSkipping	rerenderSingleSiblingByPropsChange	1.698	1.689	-0.5%	4095	4095	-0.0%
SquareishTree_ComposeSkipping	rerenderSingleSiblingViaStateChange	0.245	0.271	+10.5%	336	336	-0.0%
SquareishTree_ComposeSkipping	stableHandlers_manyCallbacks_propChange	0.439	0.460	+4.6%	2743	2743	-0.0%
SquareishTree_ComposeSkipping	tearDownAllChildren	7.381	7.692	+4.2%	26324	26325	+0.0%
SquareishTree_ComposeSkipping	tearDownSingleSibling	2.097	2.053	-2.1%	4185	4185	+0.0%
SquareishTree_ComposeSkipping	wideSiblingKeys_initialRenderAllChildren	4.743	5.023	+5.9%	18358	18358	-0.0%
SquareishTree_ComposeSkipping	wideSiblingKeys_rerenderSingleSiblingByPropsChange	0.686	0.706	+2.9%	1296	1296	+0.0%