Clean up internal type safety checks

[SandroMaglione]

Summary

• Remove unused internal declarations, imports, copied facade helpers, and obsolete test fixtures.
• Enable noUnusedLocals and noUncheckedIndexedAccess, encoding existing array and record ownership invariants explicitly.
• Replace 31 unnecessary internal type assertions with discriminated-union narrowing and already-inferred types, while retaining casts that represent genuine schema or generic boundaries.
• Preserve the public API, runtime behavior, type inference, and benchmark profile.

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
• pnpm perf:types
• pnpm perf:runtime

No examples, public TypeScript API, inference behavior, or runtime semantics changed. The manual type-performance instantiation counts were unchanged, and runtime throughput and memory remained within normal benchmark variance.

[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	0.02s	0.02s
Import effect-machine	0.02s	0.02s
Machine.defineStates (3 states)	0.07s	0.07s
Machine.make (3 states, 2 events)	0.10s	0.11s
machine.handle (3 states, 2 transitions)	0.17s	0.15s
machine.handle (depth 8)	0.37s	0.33s
machine.handle (depth 12)	0.36s	0.36s
machine.handle (depth 16)	0.38s	0.39s
machine.handle (depth 24)	0.44s	0.44s
machine.handle (wide depth 16)	0.46s	0.47s
machine.handle (parallel/history/choice)	0.41s	0.40s
machine.handle (4 successive calls)	0.36s	0.37s
machine exact input/output/error/services	0.34s	0.33s
execution adapter readiness	0.37s	0.38s

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	135,348 transitions/s	135,966 transitions/s	13,510 transitions/s
Drain burst with terminal fence	557,060 increments/s	405,444 increments/s	200,023 increments/s
Drain burst with a change observer	506,197 increments/s	401,529 increments/s	198,344 increments/s
Lookup and send to one child	427,303 increments/s	389,214 increments/s	191,975 increments/s
Start and stop a machine	173,280 machines/s	185,529 machines/s	147,863 machines/s
Start and stop a parent with one child	39,990 families/s	68,890 families/s	42,116 families/s
Plan transitions through a compound state	122,866 transitions/s	—	—
Plan transitions through parallel regions	92,260 transitions/s	—	—
Drain burst through a compound state	543,316 events/s	348,677 events/s	197,579 events/s
Drain burst through two parallel regions	493,278 events/s	263,926 events/s	147,339 events/s
Drain a compound-state burst with a change observer	488,317 events/s	—	—

Effect runtime reference points

Scenario	Effect Machine	Effect runtime primitives
Start and stop a raw generic process	17,760 processes/s	—
Start and stop a raw compiled process	70,892 processes/s	—
Start and interrupt a suspended fiber	—	168,862 fibers/s
Start and stop a queue worker	—	116,741 workers/s
Start and stop an actor shell	—	105,396 actors/s
Start and stop two actor shells	—	66,587 families/s
Update an owner-only mutable snapshot	—	316,856,781 updates/s
Update a synchronized snapshot	—	1,555,166 updates/s
Create, resolve, and await a terminal latch	—	1,461,852 latches/s

Memory profile	Effect Machine	XState 5	XState 6 alpha	Effect runtime primitives
Idle machine	1.5 KiB	3.8 KiB	2.2 KiB	—
Raw generic managed process	12.1 KiB	—	—	—
Raw compiled process	2.6 KiB	—	—	—
Two independent idle machines	2.9 KiB	7.3 KiB	3.9 KiB	—
Idle parent with one child	4.8 KiB	5.5 KiB	4.0 KiB	—
Parent with observed child registry	8.9 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	134,036 transitions/s	0.8% MAD	135,348 transitions/s	0.2% MAD	+1.0%
Drain burst with terminal fence	554,780 increments/s	3.4% MAD	557,060 increments/s	1.8% MAD	+0.4%
Drain burst with a change observer	504,926 increments/s	2.7% MAD	506,197 increments/s	0.9% MAD	+0.3%
Lookup and send to one child	425,934 increments/s	1.8% MAD	427,303 increments/s	1.9% MAD	+0.3%
Start and stop a machine	177,936 machines/s	5.2% MAD	173,280 machines/s	1.4% MAD	-2.6%
Start and stop a parent with one child	36,415 families/s	5.7% MAD	39,990 families/s	4.3% MAD	+9.8%
Plan transitions through a compound state	126,345 transitions/s	3.6% MAD	122,866 transitions/s	1.1% MAD	-2.8%
Plan transitions through parallel regions	93,791 transitions/s	2.9% MAD	92,260 transitions/s	0.7% MAD	-1.6%
Drain burst through a compound state	553,228 events/s	1.4% MAD	543,316 events/s	1.8% MAD	-1.8%
Drain burst through two parallel regions	502,445 events/s	1.5% MAD	493,278 events/s	1.7% MAD	-1.8%
Drain a compound-state burst with a change observer	505,817 events/s	2.2% MAD	488,317 events/s	4.1% MAD	-3.5%
Idle machine heap per unit	1.5 KiB	0.1% MAD	1.5 KiB	0.0% MAD	-0.0%
Raw generic managed process heap per unit	12.1 KiB	0.0% MAD	12.1 KiB	0.0% MAD	-0.0%
Raw compiled process heap per unit	2.6 KiB	0.0% MAD	2.6 KiB	0.1% MAD	+0.1%
Two independent idle machines heap per unit	2.9 KiB	0.0% MAD	2.9 KiB	0.2% 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	8.9 KiB	0.0% MAD	8.9 KiB	0.0% MAD	-0.0%
Parent with observed invoked child snapshots heap per unit	5.0 KiB	0.2% MAD	5.0 KiB	0.2% MAD	-0.0%

Effect runtime reference change from base

Metric	Base	Base variability	PR	PR variability	Difference
Start and stop a raw generic process	18,358 processes/s	1.4% MAD	17,760 processes/s	4.3% MAD	-3.3%
Start and stop a raw compiled process	70,244 processes/s	0.9% MAD	70,892 processes/s	2.7% MAD	+0.9%
Start and interrupt a suspended fiber	169,176 fibers/s	0.5% MAD	168,862 fibers/s	0.5% MAD	-0.2%
Start and stop a queue worker	117,702 workers/s	2.9% MAD	116,741 workers/s	0.2% MAD	-0.8%
Start and stop an actor shell	107,910 actors/s	2.9% MAD	105,396 actors/s	1.7% MAD	-2.3%
Start and stop two actor shells	67,577 families/s	3.3% MAD	66,587 families/s	0.7% MAD	-1.5%
Update an owner-only mutable snapshot	317,863,954 updates/s	0.0% MAD	316,856,781 updates/s	0.0% MAD	-0.3%
Update a synchronized snapshot	1,642,403 updates/s	0.4% MAD	1,555,166 updates/s	2.0% MAD	-5.3%
Create, resolve, and await a terminal latch	1,449,811 latches/s	2.8% MAD	1,461,852 latches/s	3.8% MAD	+0.8%

Versions and interpretation

• Effect Machine: 0.3.0
• XState 5: 5.32.5
• XState 6 alpha: 6.0.0-alpha.31
• Effect runtime primitives: 4.0.0-beta.107

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.