Upgrade Effect to 4.0.0-rc.108

[SandroMaglione]

Summary

• upgrade effect, @effect/vitest, and @effect/atom-react from 4.0.0-beta.107 to 4.0.0-rc.108
• refresh the root and standalone example lockfiles
• add a minor changeset for @typeonce/effect-machine
• no source compatibility changes were required

Changeset

• Added or updated for a library or package-metadata change
• Not required because this PR does not change src/ or package.json

Validation

• pnpm check
• Relevant example checks, when examples changed
• Reviewed the automated type-performance report, when the public TypeScript API or inference changed
• Reviewed the automated runtime-performance report, when runtime behavior changed

Local performance validation also passed with pnpm perf:types (all enforced instantiation budgets) and pnpm perf:runtime (completed successfully on Node 24.16.0 / Apple M1). The GitHub workflows will provide the base-versus-PR comparisons.

[github-actions]

Type performance

Measured with TypeScript 6.0.3 and skipLibCheck=true.

Scenario	Base	PR	Difference
Effect only	55	55	0 (0.0%)
Import effect-machine	55	55	0 (0.0%)
Machine.defineStates (3 states)	2,965	2,965	0 (0.0%)
Machine.make (3 states, 2 events)	8,715	8,715	0 (0.0%)
machine.handle (3 states, 2 transitions)	23,492	23,492	0 (0.0%)
machine.handle (depth 8)	117,075	117,075	0 (0.0%)
machine.handle (depth 12)	129,713	129,713	0 (0.0%)
machine.handle (depth 16)	145,055	145,055	0 (0.0%)
machine.handle (depth 24)	183,851	183,851	0 (0.0%)
machine.handle (wide depth 16)	214,189	214,189	0 (0.0%)
machine.handle (parallel/history/choice)	132,667	132,667	0 (0.0%)
machine.handle (4 successive calls)	128,674	128,674	0 (0.0%)
machine exact input/output/error/services	110,584	110,584	0 (0.0%)
execution adapter readiness	127,854	127,854	0 (0.0%)

Marginal instantiations are measured against the matching setup without that API call:

Scenario	Base	PR	Difference
Import effect-machine	0	0	0
Machine.defineStates (3 states)	2,910	2,910	0 (0.0%)
Machine.make (3 states, 2 events)	5,742	5,742	0 (0.0%)
machine.handle (3 states, 2 transitions)	14,777	14,777	0 (0.0%)
machine.handle (depth 8)	109,601	109,601	0 (0.0%)
machine.handle (depth 12)	121,039	121,039	0 (0.0%)
machine.handle (depth 16)	135,181	135,181	0 (0.0%)
machine.handle (depth 24)	171,577	171,577	0 (0.0%)
machine.handle (wide depth 16)	202,224	202,224	0 (0.0%)
machine.handle (parallel/history/choice)	114,331	114,331	0 (0.0%)
machine.handle (4 successive calls)	113,703	113,703	0 (0.0%)
machine exact input/output/error/services	100,670	100,670	0 (0.0%)
execution adapter readiness	102,092	102,092	0 (0.0%)

Check times (informational)

Scenario	Base	PR
Effect only	0.05s	0.03s
Import effect-machine	0.03s	0.03s
Machine.defineStates (3 states)	0.09s	0.09s
Machine.make (3 states, 2 events)	0.15s	0.15s
machine.handle (3 states, 2 transitions)	0.20s	0.20s
machine.handle (depth 8)	0.46s	0.49s
machine.handle (depth 12)	0.53s	0.51s
machine.handle (depth 16)	0.54s	0.54s
machine.handle (depth 24)	0.64s	0.63s
machine.handle (wide depth 16)	0.69s	0.70s
machine.handle (parallel/history/choice)	0.56s	0.57s
machine.handle (4 successive calls)	0.52s	0.54s
machine exact input/output/error/services	0.46s	0.47s
execution adapter readiness	0.51s	0.52s

Type instantiations are the comparison metric. Check time varies with runner load and is informational only.

[github-actions]

Runtime performance

Median of 5 independent benchmark processes on AMD EPYC 7763 64-Core Processor with Node v24.18.0.

Pull request baseline

Scenario	Effect Machine	XState 5	XState 6 alpha
Plan counter transitions	132,585 transitions/s	134,424 transitions/s	283,917 transitions/s
Drain burst with terminal fence	513,109 increments/s	393,669 increments/s	540,236 increments/s
Drain burst with a change observer	471,808 increments/s	391,108 increments/s	538,743 increments/s
Lookup and send to one child	408,153 increments/s	386,967 increments/s	506,539 increments/s
Start and stop a machine	173,310 machines/s	187,617 machines/s	184,843 machines/s
Start and stop a parent with one child	36,819 families/s	70,636 families/s	47,059 families/s
Plan transitions through a compound state	119,680 transitions/s	—	—
Plan transitions through parallel regions	91,389 transitions/s	—	—
Drain burst through a compound state	502,861 events/s	344,262 events/s	514,198 events/s
Drain burst through two parallel regions	465,777 events/s	261,562 events/s	430,419 events/s
Drain a compound-state burst with a change observer	458,241 events/s	—	—

Effect runtime reference points

Scenario	Effect Machine	Effect runtime primitives
Start and stop a raw generic process	16,886 processes/s	—
Start and stop a raw compiled process	67,259 processes/s	—
Start and interrupt a suspended fiber	—	166,611 fibers/s
Start and stop a queue worker	—	114,850 workers/s
Start and stop an actor shell	—	106,180 actors/s
Start and stop two actor shells	—	66,278 families/s
Update an owner-only mutable snapshot	—	316,856,781 updates/s
Update a synchronized snapshot	—	1,529,342 updates/s
Create, resolve, and await a terminal latch	—	1,456,758 latches/s

Memory profile	Effect Machine	XState 5	XState 6 alpha	Effect runtime primitives
Idle machine	1.5 KiB	3.8 KiB	1.5 KiB	—
Raw generic managed process	12.7 KiB	—	—	—
Raw compiled process	2.8 KiB	—	—	—
Two independent idle machines	3.0 KiB	7.3 KiB	2.7 KiB	—
Idle parent with one child	4.8 KiB	5.5 KiB	3.4 KiB	—
Parent with observed child registry	9.0 KiB	—	—	—
Parent with observed invoked child snapshots	5.0 KiB	—	—	—
Suspended Effect fiber	—	—	—	0.6 KiB
Effect queue with waiting fiber	—	—	—	2.8 KiB
Effect mailbox actor shell	—	—	—	3.2 KiB
Two Effect actor shells	—	—	—	6.8 KiB

Effect Machine change from base

Metric	Base	Base variability	PR	PR variability	Difference
Plan counter transitions	124,936 transitions/s	3.0% MAD	132,585 transitions/s	1.5% MAD	+6.1%
Drain burst with terminal fence	486,632 increments/s	1.8% MAD	513,109 increments/s	2.8% MAD	+5.4%
Drain burst with a change observer	453,124 increments/s	1.9% MAD	471,808 increments/s	2.2% MAD	+4.1%
Lookup and send to one child	390,692 increments/s	2.5% MAD	408,153 increments/s	0.6% MAD	+4.5%
Start and stop a machine	172,384 machines/s	2.5% MAD	173,310 machines/s	0.5% MAD	+0.5%
Start and stop a parent with one child	33,282 families/s	3.0% MAD	36,819 families/s	5.6% MAD	+10.6%
Plan transitions through a compound state	118,365 transitions/s	0.3% MAD	119,680 transitions/s	0.8% MAD	+1.1%
Plan transitions through parallel regions	92,762 transitions/s	0.6% MAD	91,389 transitions/s	1.7% MAD	-1.5%
Drain burst through a compound state	470,999 events/s	5.0% MAD	502,861 events/s	0.5% MAD	+6.8%
Drain burst through two parallel regions	460,354 events/s	4.4% MAD	465,777 events/s	0.8% MAD	+1.2%
Drain a compound-state burst with a change observer	454,892 events/s	5.2% MAD	458,241 events/s	1.6% MAD	+0.7%
Idle machine heap per unit	1.5 KiB	0.1% MAD	1.5 KiB	0.1% MAD	-0.1%
Raw generic managed process heap per unit	12.6 KiB	0.0% MAD	12.7 KiB	0.0% MAD	+0.0%
Raw compiled process heap per unit	2.8 KiB	0.1% MAD	2.8 KiB	0.0% MAD	-0.1%
Two independent idle machines heap per unit	3.0 KiB	0.0% MAD	3.0 KiB	0.0% MAD	-0.0%
Idle parent with one child heap per unit	4.8 KiB	0.0% MAD	4.8 KiB	0.0% MAD	-0.0%
Parent with observed child registry heap per unit	9.0 KiB	0.0% MAD	9.0 KiB	0.0% MAD	+0.0%
Parent with observed invoked child snapshots heap per unit	5.0 KiB	0.0% MAD	5.0 KiB	0.0% MAD	+0.0%

Effect runtime reference change from base

Metric	Base	Base variability	PR	PR variability	Difference
Start and stop a raw generic process	17,007 processes/s	1.7% MAD	16,886 processes/s	1.1% MAD	-0.7%
Start and stop a raw compiled process	67,995 processes/s	0.7% MAD	67,259 processes/s	2.2% MAD	-1.1%
Start and interrupt a suspended fiber	164,690 fibers/s	0.5% MAD	166,611 fibers/s	0.5% MAD	+1.2%
Start and stop a queue worker	116,185 workers/s	1.5% MAD	114,850 workers/s	2.0% MAD	-1.1%
Start and stop an actor shell	107,446 actors/s	1.1% MAD	106,180 actors/s	0.6% MAD	-1.2%
Start and stop two actor shells	67,714 families/s	0.4% MAD	66,278 families/s	0.7% MAD	-2.1%
Update an owner-only mutable snapshot	316,856,781 updates/s	0.0% MAD	316,856,781 updates/s	0.0% MAD	0.0%
Update a synchronized snapshot	1,564,975 updates/s	0.7% MAD	1,529,342 updates/s	1.2% MAD	-2.3%
Create, resolve, and await a terminal latch	1,452,853 latches/s	0.6% MAD	1,456,758 latches/s	2.9% MAD	+0.3%

Versions and interpretation

• Effect Machine: 0.5.1
• XState 5: 5.32.5
• XState 6 alpha: 6.0.0-alpha.36
• Effect runtime primitives: 4.0.0-rc.108

Higher throughput is better; lower heap is better. Variability is the median absolute deviation across independent processes, relative to their median. Runtime measurements on shared GitHub-hosted hardware remain informational, so small differences should be confirmed across multiple workflow runs.