Add active state value updates

[SandroMaglione]

Summary

• add typed to.local.update and active-ancestor .update selections
• preserve topology and state-owned work while supporting eventless stabilization, inspection, verification, and visualization
• implement matching generic and indexed planner semantics with differential coverage

Changeset

• Added or updated a changeset for public or package-facing changes
• Not required because this pull request only changes tests, documentation, CI, or internal tooling

Validation

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

[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.states (3 states)	3,039	3,039	0 (0.0%)
Machine.make (3 states, 2 events)	10,759	10,759	0 (0.0%)
machine.handle (3 states, 2 transitions)	28,192	28,191	-1 (-0.0%)
fluent transition (10 named branches)	106,025	112,798	+6,773 (+6.4%)
fluent invocation (state-dependent Effect)	92,756	99,552	+6,796 (+7.3%)
machine.handle (depth 24)	192,607	199,402	+6,795 (+3.5%)
machine.handle (wide depth 16)	220,969	227,764	+6,795 (+3.1%)
machine.handle (parallel/history/choice)	128,412	135,182	+6,770 (+5.3%)
machine definition (3 independent implementations)	127,365	134,256	+6,891 (+5.4%)
machine exact input/output/error/services	113,943	120,715	+6,772 (+5.9%)
execution adapter readiness	120,605	127,375	+6,770 (+5.6%)

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

Scenario	Base	PR	Difference
Import effect-machine	0	0	0
Machine.states (3 states)	2,984	2,984	0 (0.0%)
Machine.make (3 states, 2 events)	7,712	7,712	0 (0.0%)
machine.handle (3 states, 2 transitions)	17,433	17,432	-1 (-0.0%)
fluent transition (10 named branches)	95,776	102,549	+6,773 (+7.1%)
fluent invocation (state-dependent Effect)	83,491	90,287	+6,796 (+8.1%)
machine.handle (depth 24)	171,911	178,706	+6,795 (+4.0%)
machine.handle (wide depth 16)	201,480	208,275	+6,795 (+3.4%)
machine.handle (parallel/history/choice)	108,149	114,919	+6,770 (+6.3%)
machine definition (3 independent implementations)	111,396	118,287	+6,891 (+6.2%)
machine exact input/output/error/services	99,432	106,204	+6,772 (+6.8%)
execution adapter readiness	90,789	97,562	+6,773 (+7.5%)

Check times (informational)

Scenario	Base	PR
Effect only	0.04s	0.03s
Import effect-machine	0.03s	0.03s
Machine.states (3 states)	0.10s	0.10s
Machine.make (3 states, 2 events)	0.16s	0.18s
machine.handle (3 states, 2 transitions)	0.26s	0.29s
fluent transition (10 named branches)	0.51s	0.56s
fluent invocation (state-dependent Effect)	0.50s	0.50s
machine.handle (depth 24)	0.80s	0.81s
machine.handle (wide depth 16)	0.81s	0.85s
machine.handle (parallel/history/choice)	0.63s	0.67s
machine definition (3 independent implementations)	0.64s	0.69s
machine exact input/output/error/services	0.59s	0.62s
execution adapter readiness	0.58s	0.60s

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 9V74 80-Core Processor with Node v24.19.0.

Pull request baseline

Scenario	Effect Machine
Plan counter transitions	113,011 transitions/s
Drain burst with terminal fence	331,673 increments/s
Drain burst with a change observer	312,369 increments/s
Lookup and send to one child	284,066 increments/s
Start and stop a machine	140,430 machines/s
Start and stop a parent with one child	40,972 families/s
Plan transitions through a compound state	98,342 transitions/s
Plan transitions through parallel regions	81,544 transitions/s
Drain burst through a compound state	271,362 events/s
Drain burst through two parallel regions	277,054 events/s
Drain a compound-state burst with a change observer	258,158 events/s

Process runtime reference points

Scenario	Effect Machine
Start and stop a raw generic process	25,472 processes/s
Start and stop a raw compiled process	65,690 processes/s

Memory profile	Effect Machine
Idle machine	1.8 KiB
Raw generic managed process	13.9 KiB
Raw compiled process	3.2 KiB
Two independent idle machines	3.4 KiB
Idle parent with one child	5.8 KiB
Parent with observed child registry	10.0 KiB
Parent with observed invoked child snapshots	6.4 KiB

Effect Machine change from base

Metric	Base	Base variability	PR	PR variability	Difference
Plan counter transitions	113,682 transitions/s	2.2% MAD	113,011 transitions/s	0.8% MAD	-0.6%
Drain burst with terminal fence	334,629 increments/s	1.1% MAD	331,673 increments/s	0.5% MAD	-0.9%
Drain burst with a change observer	313,719 increments/s	0.7% MAD	312,369 increments/s	0.4% MAD	-0.4%
Lookup and send to one child	286,266 increments/s	0.6% MAD	284,066 increments/s	0.1% MAD	-0.8%
Start and stop a machine	139,645 machines/s	1.0% MAD	140,430 machines/s	0.4% MAD	+0.6%
Start and stop a parent with one child	41,413 families/s	2.3% MAD	40,972 families/s	0.9% MAD	-1.1%
Plan transitions through a compound state	100,310 transitions/s	1.0% MAD	98,342 transitions/s	0.5% MAD	-2.0%
Plan transitions through parallel regions	82,627 transitions/s	1.9% MAD	81,544 transitions/s	0.8% MAD	-1.3%
Drain burst through a compound state	277,418 events/s	0.5% MAD	271,362 events/s	1.1% MAD	-2.2%
Drain burst through two parallel regions	282,319 events/s	0.9% MAD	277,054 events/s	1.3% MAD	-1.9%
Drain a compound-state burst with a change observer	260,992 events/s	1.0% MAD	258,158 events/s	1.6% MAD	-1.1%
Idle machine heap per unit	1.8 KiB	0.1% MAD	1.8 KiB	0.2% 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	0.4% MAD	3.2 KiB	0.0% MAD	+0.4%
Two independent idle machines heap per unit	3.4 KiB	0.0% MAD	3.4 KiB	0.0% MAD	-0.6%
Idle parent with one child heap per unit	5.8 KiB	0.0% MAD	5.8 KiB	0.0% MAD	0.0%
Parent with observed child registry heap per unit	10.0 KiB	0.0% MAD	10.0 KiB	0.0% MAD	0.0%
Parent with observed invoked child snapshots heap per unit	6.3 KiB	0.0% MAD	6.4 KiB	0.0% MAD	+0.2%

Process runtime reference change from base

Metric	Base	Base variability	PR	PR variability	Difference
Start and stop a raw generic process	26,153 processes/s	2.7% MAD	25,472 processes/s	1.3% MAD	-2.6%
Start and stop a raw compiled process	66,085 processes/s	0.3% MAD	65,690 processes/s	0.7% MAD	-0.6%

Regression guard

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

Versions and interpretation

• Effect Machine: 0.20.0

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.