Require factories for invoked Effects

[SandroMaglione]

Summary

• require Machine.invoke Effect sources to be factories evaluated on state entry
• remove direct-Effect overloads and preserve lifecycle output, error, and service inference from factory return types
• migrate documentation, examples, tests, and consumer fixtures, with a TypeScript autocomplete regression test

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
• Automated type-performance measurement passed or was not required
• Automated runtime- and memory-performance measurement passed or was not required

Type instantiations improved for the affected Machine.invoke scenario. The runtime comparison detected no large, noise-adjusted throughput or heap regressions.

[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)	3,039	3,039	0 (0.0%)
Machine.make (3 states, 2 events)	13,199	13,199	0 (0.0%)
machine.handle (3 states, 2 transitions)	30,443	30,443	0 (0.0%)
Machine.invoke (state-dependent Effect)	70,236	69,502	-734 (-1.0%)
machine.handle (depth 24)	188,212	188,193	-19 (-0.0%)
machine.handle (wide depth 16)	220,710	220,691	-19 (-0.0%)
machine.handle (parallel/history/choice)	128,069	128,050	-19 (-0.0%)
machine.handle (4 successive calls)	135,838	135,819	-19 (-0.0%)
machine exact input/output/error/services	109,952	109,933	-19 (-0.0%)
execution adapter readiness	121,683	120,876	-807 (-0.7%)

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)	2,984	2,984	0 (0.0%)
Machine.make (3 states, 2 events)	10,152	10,152	0 (0.0%)
machine.handle (3 states, 2 transitions)	17,244	17,244	0 (0.0%)
Machine.invoke (state-dependent Effect)	59,203	58,469	-734 (-1.2%)
machine.handle (depth 24)	168,143	168,124	-19 (-0.0%)
machine.handle (wide depth 16)	201,702	201,683	-19 (-0.0%)
machine.handle (parallel/history/choice)	102,415	102,396	-19 (-0.0%)
machine.handle (4 successive calls)	114,587	114,568	-19 (-0.0%)
machine exact input/output/error/services	93,421	93,402	-19 (-0.0%)
execution adapter readiness	87,555	86,748	-807 (-0.9%)

Check times (informational)

Scenario	Base	PR
Effect only	0.02s	0.02s
Import effect-machine	0.02s	0.02s
Machine.defineStates (3 states)	0.07s	0.07s
Machine.make (3 states, 2 events)	0.12s	0.12s
machine.handle (3 states, 2 transitions)	0.18s	0.18s
Machine.invoke (state-dependent Effect)	0.27s	0.26s
machine.handle (depth 24)	0.43s	0.46s
machine.handle (wide depth 16)	0.47s	0.47s
machine.handle (parallel/history/choice)	0.36s	0.38s
machine.handle (4 successive calls)	0.39s	0.37s
machine exact input/output/error/services	0.33s	0.34s
execution adapter readiness	0.36s	0.37s

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 v24.19.0.

Pull request baseline

Scenario	Effect Machine
Plan counter transitions	124,673 transitions/s
Drain burst with terminal fence	387,750 increments/s
Drain burst with a change observer	354,953 increments/s
Lookup and send to one child	316,972 increments/s
Start and stop a machine	152,602 machines/s
Start and stop a parent with one child	32,104 families/s
Plan transitions through a compound state	113,741 transitions/s
Plan transitions through parallel regions	88,560 transitions/s
Drain burst through a compound state	362,598 events/s
Drain burst through two parallel regions	337,941 events/s
Drain a compound-state burst with a change observer	342,600 events/s

Process runtime reference points

Scenario	Effect Machine
Start and stop a raw generic process	15,169 processes/s
Start and stop a raw compiled process	63,171 processes/s

Memory profile	Effect Machine
Idle machine	1.8 KiB
Raw generic managed process	13.9 KiB
Raw compiled process	3.1 KiB
Two independent idle machines	3.4 KiB
Idle parent with one child	5.5 KiB
Parent with observed child registry	9.7 KiB
Parent with observed invoked child snapshots	6.0 KiB

Effect Machine change from base

Metric	Base	Base variability	PR	PR variability	Difference
Plan counter transitions	124,723 transitions/s	1.1% MAD	124,673 transitions/s	1.5% MAD	-0.0%
Drain burst with terminal fence	385,510 increments/s	2.2% MAD	387,750 increments/s	2.2% MAD	+0.6%
Drain burst with a change observer	360,185 increments/s	1.9% MAD	354,953 increments/s	1.7% MAD	-1.5%
Lookup and send to one child	316,751 increments/s	2.5% MAD	316,972 increments/s	2.3% MAD	+0.1%
Start and stop a machine	149,209 machines/s	1.3% MAD	152,602 machines/s	0.0% MAD	+2.3%
Start and stop a parent with one child	31,142 families/s	2.5% MAD	32,104 families/s	6.4% MAD	+3.1%
Plan transitions through a compound state	111,664 transitions/s	1.9% MAD	113,741 transitions/s	0.2% MAD	+1.9%
Plan transitions through parallel regions	88,144 transitions/s	1.6% MAD	88,560 transitions/s	1.0% MAD	+0.5%
Drain burst through a compound state	364,154 events/s	0.8% MAD	362,598 events/s	1.6% MAD	-0.4%
Drain burst through two parallel regions	331,406 events/s	1.5% MAD	337,941 events/s	1.8% MAD	+2.0%
Drain a compound-state burst with a change observer	340,756 events/s	1.0% MAD	342,600 events/s	1.4% MAD	+0.5%
Idle machine heap per unit	1.8 KiB	0.1% MAD	1.8 KiB	0.0% MAD	0.0%
Raw generic managed process heap per unit	13.9 KiB	0.0% MAD	13.9 KiB	0.0% MAD	+0.0%
Raw compiled process heap per unit	3.1 KiB	0.6% MAD	3.1 KiB	0.4% MAD	-0.1%
Two independent idle machines heap per unit	3.4 KiB	0.0% MAD	3.4 KiB	0.0% MAD	-0.0%
Idle parent with one child heap per unit	5.5 KiB	0.0% MAD	5.5 KiB	0.0% MAD	0.0%
Parent with observed child registry heap per unit	9.7 KiB	0.0% MAD	9.7 KiB	0.0% MAD	-0.0%
Parent with observed invoked child snapshots heap per unit	6.0 KiB	0.0% MAD	6.0 KiB	0.1% MAD	-0.0%

Process runtime reference change from base

Metric	Base	Base variability	PR	PR variability	Difference
Start and stop a raw generic process	15,549 processes/s	1.1% MAD	15,169 processes/s	0.8% MAD	-2.4%
Start and stop a raw compiled process	62,185 processes/s	2.1% MAD	63,171 processes/s	1.5% MAD	+1.6%

Regression guard

No large, noise-adjusted throughput or heap regressions detected.

Versions and interpretation

• Effect Machine: 0.12.0

Higher throughput is better; lower heap is better. Variability is the median absolute deviation across independent processes, relative to their median. Small differences on shared GitHub-hosted hardware remain informational; the required guard rejects only large changes beyond the measured noise allowance.