typescript-skills

TypeScript Rules Router

Core principle. Open one topic, not nine. The cost of this skill is what it makes you read.

• This is the only discoverable skill in the package. Everything under it is reference material.
• An internal INDEX.md is not a skill. Never invoke a topic name. Read the exact path shown for it.
• skill:// is this package's reference notation, not a protocol. Where a harness does not recognise it, translate it to the equivalent file path and read the target directly.
• You opened this in the middle of something. This is how to do that work, not a replacement for it. Name what you were doing before you start, and return to it when this is done.

Open one topic first

Match the task against the left column, and open that index.

• A reported lint or compiler diagnostic enters elsewhere. Read skill://typescript-skills/references/diagnostics-to-rules.md first, then the rule it names.

• Add a second topic only when the task crosses a real boundary.

• Do not load every topic by default. That is the waste this router exists to prevent.

• Read every row, then act on the matches, hardest to undo first. Reading a row costs nothing; the row you skipped is where the coverage went.

If the task involves...	Read this topic index
a value that may be absent, or ?. and ?? standing guard over it	skill://typescript-skills/typescript-coding-standards/INDEX.md
any, unknown, or a cast standing in for a type	skill://typescript-skills/typescript-coding-standards/INDEX.md
a switch over a union with no exhaustive check	skill://typescript-skills/typescript-coding-standards/INDEX.md
an abstraction, class or generic added before its second caller	skill://typescript-skills/typescript-coding-standards/INDEX.md
a long function somebody wants split, or mixed levels inside one	skill://typescript-skills/typescript-coding-standards/INDEX.md
a name that will not settle, for a class, an error or a field	skill://typescript-skills/typescript-coding-standards/INDEX.md
an old shape and its cutover kept side by side	skill://typescript-skills/typescript-coding-standards/INDEX.md
an SDK, provider or generated type reaching business logic	skill://typescript-skills/typescript-boundaries/INDEX.md
an API request or response shape used as a domain type	skill://typescript-skills/typescript-boundaries/INDEX.md
a mapper, transform or translator standing between them	skill://typescript-skills/typescript-boundaries/INDEX.md
a dependency constructed where it is used rather than passed in	skill://typescript-skills/typescript-composition/INDEX.md
a factory or singleton picked at runtime, or a lifecycle nobody owns	skill://typescript-skills/typescript-composition/INDEX.md
process.env read outside startup	skill://typescript-skills/typescript-configs/INDEX.md
a config value parsed, defaulted or exposed with no type	skill://typescript-skills/typescript-configs/INDEX.md
one config object every process loads, where one of them needs the value	skill://typescript-skills/typescript-configs/INDEX.md
a feature flag or a config migration mid-flight	skill://typescript-skills/typescript-configs/INDEX.md
a branch taken with no logging or tracing behind it	skill://typescript-skills/typescript-observability/INDEX.md
a log line naming what happened but not what to do about it	skill://typescript-skills/typescript-observability/INDEX.md
a secret, credential or token in a literal, a log or a config default	skill://typescript-skills/typescript-security/INDEX.md
a log or debug line printing a header, a payload or a whole request	skill://typescript-skills/typescript-security/INDEX.md
redaction running after the value was already written, or a crypto choice made by habit	skill://typescript-skills/typescript-security/INDEX.md
a test asserting on mock calls rather than on behaviour	skill://typescript-skills/typescript-testing/INDEX.md
a boundary contract no test pins	skill://typescript-skills/typescript-testing/INDEX.md
a coverage number or gate that moved	skill://typescript-skills/typescript-testing/INDEX.md
a refactor starting with no characterization test	skill://typescript-skills/typescript-testing/INDEX.md
a throw where a result type was meant, or the reverse	skill://typescript-skills/typescript-error-handling/INDEX.md
an error crossing a boundary with its retryability unstated	skill://typescript-skills/typescript-error-handling/INDEX.md
a catch swallowing the cause	skill://typescript-skills/typescript-error-handling/INDEX.md
Promise.all, sequential awaits, or an unawaited promise	skill://typescript-skills/typescript-async/INDEX.md
cleanup in a finally or a using, or work still running after the response	skill://typescript-skills/typescript-async/INDEX.md
AbortSignal cleanup, retry and backoff, or SIGTERM shutdown	skill://typescript-skills/typescript-async/INDEX.md

Default stance.

• Open one topic, not nine. A second one only where the task crosses a real boundary.
• Follow the conventions the repository already has, unless a rule protects a stronger invariant.
• Add structure only when the pressure is real, and let the topic's own rules say when it is.

Tie-breakers

Only a genuinely ambiguous case belongs here. Everything else routes above.

Situation	Primary	Secondary
a provider response shape enters business logic	skill://typescript-skills/typescript-boundaries/INDEX.md	coding standards, for naming
provider selection happens at startup	skill://typescript-skills/typescript-composition/INDEX.md	boundaries, if provider shapes cross inward
a secret source pointer appears in config	skill://typescript-skills/typescript-security/INDEX.md	configs, for parsing and exposure
a development value is used as a code default	skill://typescript-skills/typescript-security/INDEX.md	configs, only for non-secret behaviour defaults
a cast is applied to parsed or unknown data	skill://typescript-skills/typescript-coding-standards/INDEX.md	configs for parser shape, boundaries for transport data
a broad config object enters feature modules	skill://typescript-skills/typescript-configs/INDEX.md	composition, if framework assembly is involved
a stage comparison selects a resource	skill://typescript-skills/typescript-configs/rules/feature-decisions.md	skill://typescript-skills/typescript-configs/rules/validation-vs-verification.md
log or trace attributes may carry secrets	skill://typescript-skills/typescript-security/INDEX.md	observability, for the diagnostic shape
a refactor precedes a behaviour change	skill://typescript-skills/typescript-testing/INDEX.md	the relevant design topic
a retry loop retries caller errors too	skill://typescript-skills/typescript-error-handling/rules/error-classification.md	skill://typescript-skills/typescript-async/rules/retry-and-backoff.md for the mechanism
a handler returns an SDK error shape to a client	skill://typescript-skills/typescript-error-handling/rules/error-boundary-contract.md	boundaries, for inbound mapping
a catch returns a fallback with no signal	skill://typescript-skills/typescript-error-handling/rules/error-boundary-contract.md	observability, for the signal shape

Router contract

• The selected topic index owns routing inside its domain.
• The canonical rule files own the design decisions.
• A named diagnostic routes through skill://typescript-skills/references/diagnostics-to-rules.md.
• For authoring conventions, read skill://typescript-skills/references/authoring-checklist.md.
• What is still open lives in docs/typescript-skills/ at the repository root.