Verify routed transition evidence

[SandroMaglione]

Summary

• accept startup configurations that cross roots through an exact retained initial-choice route
• verify each retained resolved target against its selected static branch and retained choice or history route
• cover chained choices, history, simultaneous transitions, and generic/optimized choice-history traces

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 (no examples changed)
• Automated type-performance measurement passed or was not required
• Automated runtime- and memory-performance measurement passed or was not required

Local pnpm perf:types and pnpm perf:runtime checks passed; CI comparisons remain authoritative.

[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)	10,439	10,439	0 (0.0%)
machine.handle (3 states, 2 transitions)	53,206	53,206	0 (0.0%)
Machine.transition (10 conditional cases)	116,110	116,110	0 (0.0%)
Machine.invoke (state-dependent Effect)	57,187	57,187	0 (0.0%)
machine.handle (depth 24)	188,289	188,289	0 (0.0%)
machine.handle (wide depth 16)	219,355	219,355	0 (0.0%)
machine.handle (parallel/history/choice)	132,085	132,085	0 (0.0%)
machine.handle (4 successive calls)	137,762	137,762	0 (0.0%)
machine exact input/output/error/services	114,832	114,832	0 (0.0%)
execution adapter readiness	124,664	124,664	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)	2,984	2,984	0 (0.0%)
Machine.make (3 states, 2 events)	7,392	7,392	0 (0.0%)
machine.handle (3 states, 2 transitions)	42,767	42,767	0 (0.0%)
Machine.transition (10 conditional cases)	106,181	106,181	0 (0.0%)
Machine.invoke (state-dependent Effect)	48,341	48,341	0 (0.0%)
machine.handle (depth 24)	168,599	168,599	0 (0.0%)
machine.handle (wide depth 16)	200,664	200,664	0 (0.0%)
machine.handle (parallel/history/choice)	112,409	112,409	0 (0.0%)
machine.handle (4 successive calls)	122,216	122,216	0 (0.0%)
machine exact input/output/error/services	100,741	100,741	0 (0.0%)
execution adapter readiness	62,727	62,727	0 (0.0%)

Check times (informational)

Scenario	Base	PR
Effect only	0.03s	0.03s
Import effect-machine	0.03s	0.03s
Machine.defineStates (3 states)	0.10s	0.10s
Machine.make (3 states, 2 events)	0.16s	0.18s
machine.handle (3 states, 2 transitions)	0.34s	0.38s
Machine.transition (10 conditional cases)	0.50s	0.55s
Machine.invoke (state-dependent Effect)	0.35s	0.39s
machine.handle (depth 24)	0.76s	0.75s
machine.handle (wide depth 16)	0.75s	0.75s
machine.handle (parallel/history/choice)	0.66s	0.63s
machine.handle (4 successive calls)	0.62s	0.63s
machine exact input/output/error/services	0.60s	0.58s
execution adapter readiness	0.55s	0.58s

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	108,779 transitions/s
Drain burst with terminal fence	338,341 increments/s
Drain burst with a change observer	315,578 increments/s
Lookup and send to one child	278,203 increments/s
Start and stop a machine	138,064 machines/s
Start and stop a parent with one child	28,196 families/s
Plan transitions through a compound state	94,354 transitions/s
Plan transitions through parallel regions	77,264 transitions/s
Drain burst through a compound state	292,235 events/s
Drain burst through two parallel regions	294,473 events/s
Drain a compound-state burst with a change observer	273,906 events/s

Process runtime reference points

Scenario	Effect Machine
Start and stop a raw generic process	15,068 processes/s
Start and stop a raw compiled process	60,750 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	6.1 KiB

Effect Machine change from base

Metric	Base	Base variability	PR	PR variability	Difference
Plan counter transitions	114,368 transitions/s	1.4% MAD	108,779 transitions/s	2.1% MAD	-4.9%
Drain burst with terminal fence	343,243 increments/s	1.7% MAD	338,341 increments/s	1.4% MAD	-1.4%
Drain burst with a change observer	323,952 increments/s	1.6% MAD	315,578 increments/s	0.8% MAD	-2.6%
Lookup and send to one child	284,856 increments/s	0.4% MAD	278,203 increments/s	1.6% MAD	-2.3%
Start and stop a machine	136,184 machines/s	2.4% MAD	138,064 machines/s	0.7% MAD	+1.4%
Start and stop a parent with one child	27,857 families/s	0.9% MAD	28,196 families/s	1.3% MAD	+1.2%
Plan transitions through a compound state	98,248 transitions/s	1.3% MAD	94,354 transitions/s	1.8% MAD	-4.0%
Plan transitions through parallel regions	81,843 transitions/s	1.1% MAD	77,264 transitions/s	2.4% MAD	-5.6%
Drain burst through a compound state	297,315 events/s	1.5% MAD	292,235 events/s	1.3% MAD	-1.7%
Drain burst through two parallel regions	301,438 events/s	0.6% MAD	294,473 events/s	0.8% MAD	-2.3%
Drain a compound-state burst with a change observer	279,919 events/s	0.9% MAD	273,906 events/s	1.0% MAD	-2.1%
Idle machine heap per unit	1.8 KiB	0.1% MAD	1.8 KiB	0.0% MAD	+0.2%
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	0.2% MAD	3.1 KiB	0.1% MAD	+0.0%
Two independent idle machines heap per unit	3.4 KiB	0.1% MAD	3.4 KiB	0.1% MAD	-0.5%
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	6.1 KiB	0.0% MAD	6.1 KiB	0.0% MAD	-0.0%

Process runtime reference change from base

Metric	Base	Base variability	PR	PR variability	Difference
Start and stop a raw generic process	14,989 processes/s	1.9% MAD	15,068 processes/s	0.9% MAD	+0.5%
Start and stop a raw compiled process	60,310 processes/s	0.7% MAD	60,750 processes/s	1.4% MAD	+0.7%

Regression guard

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

Versions and interpretation

• Effect Machine: 0.13.0

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.