sindresorhus/ky

Can another program use it through a documented, machine-readable surface?

• next: L4 An API reference is generated from the code (autodoc, mkdocstrings, typedoc, …). (no generated API reference)

library ladder · level 3

• ✓ L1 An importable, packaged API exists. package.json npm package
• ✓ L2 The public API is delimited (__all__, an exports map, exported identifiers). package.json package entry point
• ✓ L3 The public API is statically typed (py.typed, type declarations, a typed language). package.json TypeScript types
• ✗ L4 An API reference is generated from the code (autodoc, mkdocstrings, typedoc, …). no generated API reference

Can integrators rely on it not changing under them?

• next: L2 A changelog exists and marks breaking changes. (no changelog)

all ladder · level 1

• ✓ L1 Releases are versioned (semver tags or versioned changelog sections). 99 semver tags, latest v2.2.0
• ✗ L2 A changelog exists and marks breaking changes. no changelog
• ✗ L3 A deprecation mechanism is used in code (warnings, @deprecated, Deprecation/Sunset headers) or the API is versioned. no deprecation mechanism or API versioning
• ✓ L4 Across tagged releases, no OpenAPI operation, CLI option or __all__ symbol was removed without first being deprecated. 20 tagged releases compared

Can others react to state changes without polling?

Can a machine act with its own revocable, least-privilege identity?

Can its data get in and out, in bulk, in open formats, with an explicit schema?

Can an automated caller use it without guessing, and recover from failure?

• next: L4 Agent docs, and examples that run as tests (doctests). (examples don't run as tests)

library ladder · level 3

• ✓ L1 Errors are specific exception types, and library code never calls sys.exit. source/errors/ForceRetryError.ts 1 matchsource/errors/KyError.ts 1 match
• ✓ L2 Inputs are validated with messages naming the bad argument. source/core/Ky.ts 17 matchessource/utils/merge.ts 8 matches
• ✓ L3 Timeouts and retries are configurable. source/core/Ky.ts 4 matchestest-d/hooks.ts 3 matches
• ✗ L4 Agent docs, and examples that run as tests (doctests). examples don't run as tests

Can another system run and compose it without a human?

• next: L3 Published to a public registry, with at most 10 runtime dependencies. (not published to a registry)

library ladder · level 2

• ✓ L1 Importable from source. package.json npm package
• ✓ L2 Installable as a package (a package manifest). package.json package manifest
• ✗ L3 Published to a public registry, with at most 10 runtime dependencies. not published to a registry
• ✗ L4 Optional features behind extras/features. no optional extras

Can behaviour be added without modifying the code?

• next: L1 Internal seams: a registry, registration function or plugin manager. (no registry or registration function)

all ladder · level 0

• ✗ L1 Internal seams: a registry, registration function or plugin manager. no registry or registration function
• ✗ L2 The docs show how to add behaviour through those seams (even in-tree). no registration functions to document
• ✗ L3 Out-of-tree extensions are discovered (entry points, a plugin directory, configuration) without editing the package. extensions must be added inside the package
• ✗ L4 The extension API is versioned, has lifecycle hooks, and has example extensions. the extension API isn't versioned

Can an operator, or an orchestrating agent, tell whether it works and why not?

• next: L1 Logs through a standard logger namespace and never prints from library code. (no standard logger)

library ladder · level 0

• ✗ L1 Logs through a standard logger namespace and never prints from library code. no standard logger
• ✗ L2 Log levels are used meaningfully (at least two levels). fewer than two log levels used
• ✗ L3 Optional metrics or tracing hooks. no metrics or tracing hooks
• ✗ L4 OpenTelemetry instrumentation available. no OpenTelemetry instrumentation

Can an agent change it safely with limited context?

• next: L3 At least 90% of modules fit 32k tokens and no file exceeds 12k; test/source token ratio at least 0.3; at least 70% of the code is typed. (100% of modules fit 32k tokens; 1 files over 12k)

all ladder · level 2

• ✓ L1 A README and some tests. readme.mdtest/base-url.ts 46 test files
• ✓ L2 CI runs the tests; applications pin dependencies (libraries and zero-dependency projects are exempt). .github/workflows/main.yml library or zero-dependency project: lockfile not required
• ✗ L3 At least 90% of modules fit 32k tokens and no file exceeds 12k; test/source token ratio at least 0.3; at least 70% of the code is typed. 100% of modules fit 32k tokens; 1 files over 12k
• ✓ L4 No import cycles, and agent docs (AGENTS.md, CLAUDE.md, llms.txt). AGENTS.md