Add interactive text machine visualizer

[SandroMaglione]

Summary

• Add a local Vite prototype that projects public machine inspection data into a serializable visualization document.
• Keep the main tree focused on state topology, with initial, active, structural, transition-count, and activity-count markers.
• Move outgoing transitions, incoming transitions, branches, updates, activities, and event registrations into a structured inspector.
• Add breadcrumb, source, target, update-owner, enabled-event, and active-state navigation.
• Add accessible tree semantics and keyboard navigation without bringing in a UI dependency.
• Accept ready, partial, and error sources so a later scanner can retain useful topology while a machine is incomplete.
• Adopt an Effect-style pnpm workspace: the published library now lives under packages/effect-machine, while the private prototype lives under packages/devtools.
• Keep devtools implementation modules internal, block internal package exports, and enforce the package boundary with an architecture check.

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
• pnpm visualizer:build
• pnpm perf:types
• Automated runtime- and memory-performance measurement passed or was not required

Browser verification covered state-only rendering, full-subtree selection, collapse and expand behavior, active-state reveal, enabled-event inspection, transition target navigation, related-state highlighting, keyboard focus movement, text-selection prevention, clearing the current inspection, and a clean browser console after the package extraction.

[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)	10,787	10,787	0 (0.0%)
machine.handle (3 states, 2 transitions)	28,551	28,551	0 (0.0%)
fluent transition (10 named branches)	122,775	122,775	0 (0.0%)
fluent invocation (state-dependent Effect)	108,429	108,429	0 (0.0%)
machine.handle (depth 24)	207,970	207,970	0 (0.0%)
machine.handle (wide depth 16)	236,332	236,332	0 (0.0%)
machine.handle (parallel/history/choice)	144,812	144,812	0 (0.0%)
machine definition (3 independent implementations)	143,617	143,617	0 (0.0%)
machine exact input/output/error/services	129,873	129,873	0 (0.0%)
execution adapter readiness	136,469	136,469	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.states (3 states)	2,984	2,984	0 (0.0%)
Machine.make (3 states, 2 events)	7,740	7,740	0 (0.0%)
machine.handle (3 states, 2 transitions)	17,764	17,764	0 (0.0%)
fluent transition (10 named branches)	112,498	112,498	0 (0.0%)
fluent invocation (state-dependent Effect)	99,018	99,018	0 (0.0%)
machine.handle (depth 24)	187,474	187,474	0 (0.0%)
machine.handle (wide depth 16)	217,043	217,043	0 (0.0%)
machine.handle (parallel/history/choice)	124,167	124,167	0 (0.0%)
machine definition (3 independent implementations)	127,576	127,576	0 (0.0%)
machine exact input/output/error/services	115,217	115,217	0 (0.0%)
execution adapter readiness	106,299	106,299	0 (0.0%)

Check times (informational)

Scenario	Base	PR
Effect only	0.03s	0.03s
Import effect-machine	0.03s	0.03s
Machine.states (3 states)	0.11s	0.11s
Machine.make (3 states, 2 events)	0.21s	0.17s
machine.handle (3 states, 2 transitions)	0.28s	0.27s
fluent transition (10 named branches)	0.59s	0.59s
fluent invocation (state-dependent Effect)	0.56s	0.57s
machine.handle (depth 24)	0.89s	0.88s
machine.handle (wide depth 16)	0.90s	0.90s
machine.handle (parallel/history/choice)	0.70s	0.71s
machine definition (3 independent implementations)	0.70s	0.72s
machine exact input/output/error/services	0.67s	0.67s
execution adapter readiness	0.68s	0.66s

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 Intel(R) Xeon(R) Platinum 8370C CPU @ 2.80GHz with Node v24.19.0.

Pull request baseline

Scenario	Effect Machine
Plan counter transitions	115,618 transitions/s
Drain burst with terminal fence	363,278 increments/s
Drain burst with a change observer	343,571 increments/s
Lookup and send to one child	302,303 increments/s
Start and stop a machine	137,043 machines/s
Start and stop a parent with one child	37,954 families/s
Plan transitions through a compound state	101,989 transitions/s
Plan transitions through parallel regions	84,145 transitions/s
Drain burst through a compound state	289,774 events/s
Drain burst through two parallel regions	284,430 events/s
Drain a compound-state burst with a change observer	274,591 events/s

Process runtime reference points

Scenario	Effect Machine
Start and stop a raw generic process	23,478 processes/s
Start and stop a raw compiled process	63,259 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	6.3 KiB

Effect Machine change from base

Metric	Base	Base variability	PR	PR variability	Difference
Plan counter transitions	114,157 transitions/s	1.7% MAD	115,618 transitions/s	1.9% MAD	+1.3%
Drain burst with terminal fence	365,249 increments/s	0.6% MAD	363,278 increments/s	1.3% MAD	-0.5%
Drain burst with a change observer	345,822 increments/s	1.3% MAD	343,571 increments/s	1.6% MAD	-0.7%
Lookup and send to one child	301,665 increments/s	0.4% MAD	302,303 increments/s	1.3% MAD	+0.2%
Start and stop a machine	134,590 machines/s	3.0% MAD	137,043 machines/s	1.8% MAD	+1.8%
Start and stop a parent with one child	37,132 families/s	0.6% MAD	37,954 families/s	2.3% MAD	+2.2%
Plan transitions through a compound state	101,235 transitions/s	1.2% MAD	101,989 transitions/s	1.5% MAD	+0.7%
Plan transitions through parallel regions	85,931 transitions/s	1.3% MAD	84,145 transitions/s	1.1% MAD	-2.1%
Drain burst through a compound state	293,066 events/s	0.9% MAD	289,774 events/s	0.8% MAD	-1.1%
Drain burst through two parallel regions	295,979 events/s	0.4% MAD	284,430 events/s	1.2% MAD	-3.9%
Drain a compound-state burst with a change observer	279,066 events/s	0.9% MAD	274,591 events/s	0.9% MAD	-1.6%
Idle machine heap per unit	1.8 KiB	0.2% MAD	1.8 KiB	0.2% MAD	+0.5%
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	3.2 KiB	0.0% MAD	3.2 KiB	0.0% MAD	+0.0%
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	5.8 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	6.3 KiB	0.0% MAD	-0.1%

Process runtime reference change from base

Metric	Base	Base variability	PR	PR variability	Difference
Start and stop a raw generic process	23,632 processes/s	2.2% MAD	23,478 processes/s	1.3% MAD	-0.7%
Start and stop a raw compiled process	64,604 processes/s	4.0% MAD	63,259 processes/s	1.9% MAD	-2.1%

Regression guard

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

Versions and interpretation

• Effect Machine: 0.22.0

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.