swift-concurrency-pro

Name: swift-concurrency-pro
Author: twostraws

495stars20forks

How to install swift-concurrency-pro?

twostraws/swift-concurrency-agent-skill/swift-concurrency-pro

$npx -y skills add twostraws/Swift-Concurrency-Agent-Skill --skill swift-concurrency-pro

Installs into the current project.

Summary

Reviews Swift code for concurrency correctness, modern API usage, and common async/await pitfalls. Use when reading, writing, or reviewing Swift concurrency code.

Files · 1

View on GitHub

SKILL.md

1	Review Swift concurrency code for correctness, modern API usage, and adherence to project conventions. Report only genuine problems - do not nitpick or invent issues.
2
3	Review process:
4
5	1. Scan for known-dangerous patterns using `references/hotspots.md` to prioritize what to inspect.
6	1. Check for recent Swift 6.2 concurrency behavior using `references/new-features.md`.
7	1. Validate actor usage for reentrancy and isolation correctness using `references/actors.md`.
8	1. Ensure structured concurrency is preferred over unstructured where appropriate using `references/structured.md`.
9	1. Check unstructured task usage for correctness using `references/unstructured.md`.
10	1. Verify cancellation is handled correctly using `references/cancellation.md`.
11	1. Validate async stream and continuation usage using `references/async-streams.md`.
12	1. Check bridging code between sync and async worlds using `references/bridging.md`.
13	1. Review any legacy concurrency migrations using `references/interop.md`.
14	1. Cross-check against common failure modes using `references/bug-patterns.md`.
15	1. If the project has strict-concurrency errors, map diagnostics to fixes using `references/diagnostics.md`.
16	1. If reviewing tests, check async test patterns using `references/testing.md`.
17
18	If doing a partial review, load only the relevant reference files.
19
20
21	## Core Instructions
22
23	- Target Swift 6.2 or later with strict concurrency checking.
24	- If code spans multiple targets or packages, compare their concurrency build settings before assuming behavior should match.
25	- Prefer structured concurrency (task groups) over unstructured (`Task {}`).
26	- Prefer Swift concurrency over Grand Central Dispatch for new code. GCD is still acceptable in low-level code, framework interop, or performance-critical synchronous work where queues and locks are the right tool – don't flag these as errors.
27	- If an API offers both `async`/`await` and closure-based variants, always prefer `async`/`await`.
28	- Do not introduce third-party concurrency frameworks without asking first.
29	- Do not suggest `@unchecked Sendable` to fix compiler errors. It silences the diagnostic without fixing the underlying race. Prefer actors, value types, or `sending` parameters instead. The only legitimate use is for types with internal locking that are provably thread-safe.
30
31
32	## Output Format
33
34	Organize findings by file. For each issue:
35
36	1. State the file and relevant line(s).
37	2. Name the rule being violated.
38	3. Show a brief before/after code fix.
39
40	Skip files with no issues. End with a prioritized summary of the most impactful changes to make first.
41
42	Example output:
43
44	### DataLoader.swift
45
46	Line 18: Actor reentrancy – state may have changed across the `await`.
47
48	```swift
49	// Before
50	actor Cache {
51	var items: [String: Data] = [:]
52
53	func fetch(_ key: String) async throws -> Data {
54	if items[key] == nil {
55	items[key] = try await download(key)
56	}
57	return items[key]!
58	}
59	}
60
61	// After
62	actor Cache {
63	var items: [String: Data] = [:]
64
65	func fetch(_ key: String) async throws -> Data {
66	if let existing = items[key] { return existing }
67	let data = try await download(key)
68	items[key] = data
69	return data
70	}
71	}
72	```
73
74	Line 34: Use `withTaskGroup` instead of creating tasks in a loop.
75
76	```swift
77	// Before
78	for url in urls {
79	Task { try await fetch(url) }
80	}
81
82	// After
83	try await withThrowingTaskGroup(of: Data.self) { group in
84	for url in urls {
85	group.addTask { try await fetch(url) }
86	}
87
88	for try await result in group {
89	process(result)
90	}
91	}
92	```
93
94	### Summary
95
96	1. Correctness (high): Actor reentrancy bug on line 18 may cause duplicate downloads and a force-unwrap crash.
97	2. Structure (medium): Unstructured tasks in loop on line 34 lose cancellation propagation.
98
99	End of example.
100
101
102	## References
103
104	- `references/hotspots.md` - Grep targets for code review: known-dangerous patterns and what to check for each.
105	- `references/new-features.md` - Swift 6.2 changes that alter review advice: default actor isolation, isolated conformances, caller-actor async behavior, `@concurrent`, `Task.immediate`, task naming, and priority escalation.
106	- `references/actors.md` - Actor reentrancy, shared-state annotations, global actor inference, and isolation patterns.
107	- `references/structured.md` - Task groups over loops, discarding task groups, concurrency limits.
108	- `references/unstructured.md` - Task vs Task.detached, when Task {} is a code smell.
109	- `references/cancellation.md` - Cancellation propagation, cooperative checking, broken cancellation patterns.
110	- `references/async-streams.md` - AsyncStream factory, continuation lifecycle, back-pressure.
111	- `references/bridging.md` -

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Type

swift-concurrency-pro

495stars20forks

View on GitHub

How to install swift-concurrency-pro?

twostraws/swift-concurrency-agent-skill/swift-concurrency-pro

$npx -y skills add twostraws/Swift-Concurrency-Agent-Skill --skill swift-concurrency-pro

Installs into the current project.

Summary

Reviews Swift code for concurrency correctness, modern API usage, and common async/await pitfalls. Use when reading, writing, or reviewing Swift concurrency code.

Files · 1

View on GitHub

SKILL.md

1	Review Swift concurrency code for correctness, modern API usage, and adherence to project conventions. Report only genuine problems - do not nitpick or invent issues.
2
3	Review process:
4
5	1. Scan for known-dangerous patterns using `references/hotspots.md` to prioritize what to inspect.
6	1. Check for recent Swift 6.2 concurrency behavior using `references/new-features.md`.
7	1. Validate actor usage for reentrancy and isolation correctness using `references/actors.md`.
8	1. Ensure structured concurrency is preferred over unstructured where appropriate using `references/structured.md`.
9	1. Check unstructured task usage for correctness using `references/unstructured.md`.
10	1. Verify cancellation is handled correctly using `references/cancellation.md`.
11	1. Validate async stream and continuation usage using `references/async-streams.md`.
12	1. Check bridging code between sync and async worlds using `references/bridging.md`.
13	1. Review any legacy concurrency migrations using `references/interop.md`.
14	1. Cross-check against common failure modes using `references/bug-patterns.md`.
15	1. If the project has strict-concurrency errors, map diagnostics to fixes using `references/diagnostics.md`.
16	1. If reviewing tests, check async test patterns using `references/testing.md`.
17
18	If doing a partial review, load only the relevant reference files.
19
20
21	## Core Instructions
22
23	- Target Swift 6.2 or later with strict concurrency checking.
24	- If code spans multiple targets or packages, compare their concurrency build settings before assuming behavior should match.
25	- Prefer structured concurrency (task groups) over unstructured (`Task {}`).
26	- Prefer Swift concurrency over Grand Central Dispatch for new code. GCD is still acceptable in low-level code, framework interop, or performance-critical synchronous work where queues and locks are the right tool – don't flag these as errors.
27	- If an API offers both `async`/`await` and closure-based variants, always prefer `async`/`await`.
28	- Do not introduce third-party concurrency frameworks without asking first.
29	- Do not suggest `@unchecked Sendable` to fix compiler errors. It silences the diagnostic without fixing the underlying race. Prefer actors, value types, or `sending` parameters instead. The only legitimate use is for types with internal locking that are provably thread-safe.
30
31
32	## Output Format
33
34	Organize findings by file. For each issue:
35
36	1. State the file and relevant line(s).
37	2. Name the rule being violated.
38	3. Show a brief before/after code fix.
39
40	Skip files with no issues. End with a prioritized summary of the most impactful changes to make first.
41
42	Example output:
43
44	### DataLoader.swift
45
46	Line 18: Actor reentrancy – state may have changed across the `await`.
47
48	```swift
49	// Before
50	actor Cache {
51	var items: [String: Data] = [:]
52
53	func fetch(_ key: String) async throws -> Data {
54	if items[key] == nil {
55	items[key] = try await download(key)
56	}
57	return items[key]!
58	}
59	}
60
61	// After
62	actor Cache {
63	var items: [String: Data] = [:]
64
65	func fetch(_ key: String) async throws -> Data {
66	if let existing = items[key] { return existing }
67	let data = try await download(key)
68	items[key] = data
69	return data
70	}
71	}
72	```
73
74	Line 34: Use `withTaskGroup` instead of creating tasks in a loop.
75
76	```swift
77	// Before
78	for url in urls {
79	Task { try await fetch(url) }
80	}
81
82	// After
83	try await withThrowingTaskGroup(of: Data.self) { group in
84	for url in urls {
85	group.addTask { try await fetch(url) }
86	}
87
88	for try await result in group {
89	process(result)
90	}
91	}
92	```
93
94	### Summary
95
96	1. Correctness (high): Actor reentrancy bug on line 18 may cause duplicate downloads and a force-unwrap crash.
97	2. Structure (medium): Unstructured tasks in loop on line 34 lose cancellation propagation.
98
99	End of example.
100
101
102	## References
103
104	- `references/hotspots.md` - Grep targets for code review: known-dangerous patterns and what to check for each.
105	- `references/new-features.md` - Swift 6.2 changes that alter review advice: default actor isolation, isolated conformances, caller-actor async behavior, `@concurrent`, `Task.immediate`, task naming, and priority escalation.
106	- `references/actors.md` - Actor reentrancy, shared-state annotations, global actor inference, and isolation patterns.
107	- `references/structured.md` - Task groups over loops, discarding task groups, concurrency limits.
108	- `references/unstructured.md` - Task vs Task.detached, when Task {} is a code smell.
109	- `references/cancellation.md` - Cancellation propagation, cooperative checking, broken cancellation patterns.
110	- `references/async-streams.md` - AsyncStream factory, continuation lifecycle, back-pressure.
111	- `references/bridging.md` -

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Type