Add a README Caveats subsection with user-facing guidance for the two
open-universe shapes: parse external input at the boundary down to a
finite union, or use a runtime Map registry for extensible domains.
Point the finite-universe bullet at it, and point the rejected
fix/open-universe-* entry in development/library.md back at the new
guidance, so rule and decision cross-reference without duplicating each
other.
`UnsupportedReason` tested `IsLiteral<PatternKey<T>> extends false`.
`IsLiteral` is `boolean` for a union that mixes a literal with a broad
type (`"a" | \`x-${number}\``), so `boolean extends false` is false and
the mix was accepted. Test `extends true` instead, which rejects it.
Found while adding property-union broad-universe coverage; the gate is
shared with the primitive-union matcher.
The tagged-union matcher selected handler parameters with
`Extract<T, Record<K, V>>`, which only keeps a member whose
discriminant is a singleton literal. A property that is itself a
union (`{ color: "red" | "green" | "blue" }`) or optional
(`{ type?: "x" }`) matched no member, so every handler received
`never`, and the fallback saw the whole shape instead of the
unhandled tags.
Replace the selector with `Narrowed`, which distributes over `T`,
drops a member whose `K` cannot take the tag, and narrows `K`. The
`T[K] extends V` fast path keeps an exact member (a discriminated
union's declared interface) untouched. The fallback reuses
`Narrowed` over `Exclude<Tags, HandledTags>`, so a union-valued
property narrows to the unhandled tags rather than the whole shape.
Matching a defined tag on an optional property makes the key
required (`{ type: "x" }`); the `undefined` tag yields
`{ type?: never }` under `exactOptionalPropertyTypes` (absence) or
`{ type?: undefined }` when the property admits an explicit
`undefined`.
Remove every done/cancelled backlog item; the reasons they recorded are
already in development/ (library.md, testing.md, tooling.md, workflow.md)
and git history is the archive.
The one exception was the TS 7 LSP shutdown workaround, which lived only in
a code comment. Record it under development/testing.md § Autocomplete
(Known issue) before dropping the bug item.
Listing scripts/*.ts in knip's `entry` replaced its default entry
detection, which derives the public entry from package.json `exports`.
Adding the CLI scripts therefore dropped the library entry, so knip
resolved the package through dist/index.js and flagged the unreferenced
src/index.ts as unused. Name the source entry alongside the scripts.
Record the rationale in development/tooling.md.
Record why open universes and value/stringification collisions are
rejected, the `Member<T, K>` inversion, and the findings from the
rejected open-universe attempt so they are not re-run.
A `boolean` / `null` / `undefined` discriminant cannot key a handler
map, so the tagged-union matcher now routes it through the
`PatternKey` / `PatternParam` projection the primitive-union matcher
already used. Both matchers share the projection from
`matcher-shared.ts`; `MapTaggedUnion`, `Handlers`, `HandledMembers`
and `MustBePartial` key off the projected form and invert it to
recover the real member.
Covers exhaustive and fallback dispatch, the redundant-fallback
guard, and the LSP popup offering the tags by name.
`getMatcher` / `getMatcherW` become `getPrimitiveUnionMatcher` /
`getPrimitiveUnionMatcherW`; `src/primitive.ts` and its test move to
`src/primitive-union.*`. The `Union` suffix mirrors `getTaggedUnionMatcher`.
A handler's `expectTypeOf(shape)` only proved the type the compiler inferred;
nothing observed the argument `dispatch` passed. Passing `String(shape)` at the
call site therefore kept the whole suite green while breaking every key whose
property name differs from its value (`true`, `null`, `1`).
Pair each handler expectation with a runtime assertion: `assert.equal` where a
handler runs for one shape, the disjunction over the set a `_` fallback accepts
where it runs for several. Where the exact value matters the fallback returns
its shape verbatim and the call site asserts it; a widening pattern absorbs the
remainder type into the return union, so the claim stays strict-free. The
mutation above now fails 10 of the 33 tests.
Rule: CONTRIBUTING.md, rationale: development/testing.md § Handler arguments.
String(shape) defeats V8's numeric-key fast path (measured ~2x on
number-keyed dispatch). JS already coerces boolean/null/undefined to the
same property key, so assert shape to string | number and index directly.
The assertion is TS2538-only; the facade keeps it sound. Needs a source
no-unsafe-type-assertion disable, next to the existing one.
State the end-user limits once, in README § Caveats: a member colliding
with its stringification, the unsupported symbol/bigint, and NaN/-0. Drop
the duplicated known-issue prose from development/library.md and the
source comment; link to the README instead.
Drop the fixed no-floating-promises header exception from CONTRIBUTING.md
and AGENTS.md; agents must not add a source disable or edit .oxlintrc.json.
Record the split in tooling.md and testing.md: a one-site false positive is a
source disable, a file-class one lives in the test override.
Extend the matcher universe beyond string | number so a union can carry
boolean, null and undefined members. true|false, null and undefined are
not property keys, so handler keys are their stringification while the
callback still receives the real member. Symbols are rejected (a brand
is compile-time only) and bigint is not a property key.
A fallback paired with a handler map that already covers `T` was still
accepted, even though its remainder is empty. Fold the guard into
`Handled`'s own (F-bounded) constraint so it is checked after inference;
a conditional in the fallback parameter is evaluated while `Handled` is
still its constraint and rejects every partial map whose handler callbacks
need contextual typing.
Rewrite development/library.md around the new shape: the fallback is a second
argument (so it can receive the remainder), `R` needs an inference site in the
handler map, `Exact` restores the excess-property check, and the overload order
is load-bearing. Record this branch's rejected alternatives (single-object `_`,
currying, `this`/HKT, variance/`const`/`NoInfer`/brands) and the redundant-
fallback known issue. Add the changelog note and check off the backlog task.
The protocol cross-link and the TS-internal shutdown-race explanation were
too detailed for the category doc. The helper comment keeps a short,
self-contained note on the stdin-EOF workaround.
The TS 7 Go server races Session.updateWatches against the exit
notification; handleExit returns io.EOF, the background context is
cancelled, and the bare error is flushed to stderr once the outgoing
queue closes (server.go / logger.go). Send shutdown and close stdin
instead: EOF makes the server exit cleanly (code 0, no output), with the
kill kept as a fallback. testing.md records the cause.
Note that the autocomplete helper drives the server through
vscode-languageserver-protocol, cross-link the tooling decision, and replace
the obsolete string-id known issue with the benign context-canceled stderr
the Go server emits on shutdown.
The autocomplete helper drives tsc --lsp --stdio; vscode-languageserver-protocol
supplies the transport (re-exported vscode-jsonrpc/node) and the typed LSP
requests, replacing the hand-rolled JSON-RPC client. Record the choice and
the rejected alternatives in tooling.md.
No tests live under scripts/, and every test script (test, test:unit, test:ci,
watch:test) globs only src/**/*.test.ts, so state that. The scripts/**
oxlint scope it was confused with still exists and carries the same
import/no-nodejs-modules exception as the test-helper scope.
Drop the strict/widened aliases from src/index.ts so the factories are
exported under their own names, and align the type tests, the autocomplete
probe (which now imports the public surface from ./index.ts) and library.md
with them.
Also correct the widened-overload comment: the excess-property check does not
apply to a generic P, so MatcherWidening's keyof guard — not the closed
constraint — is what rejects keys outside T/_, as library.md already
documented.
The matcher is now two three-overload factories; library.md documents why
the union merge, inferred universe, conditional RequireKeys and cases-first
paths were rejected, and lists the two open issues (the fallback sees all of
T; a redundant _ is still accepted). testing.md records the language server
as the autocomplete oracle, and CONTRIBUTING points the exception at the
matcher's own test file.
The backlog marks the design-doc and autocomplete groundwork done alongside
the adoption.
development/testing.md § Test helpers: why name beats path under
import/no-relative-parent-imports, why the key needs `#`, why the
`__tests__` folder name, and what was rejected (flat placement, tsconfig
paths, rule exemptions).
They were the template's demo API, not the library's real surface. Drop
them, their README walkthrough, and the tooling note that cited their
disable directives, and point index.ts at the primitive matchers that
remain.
The spec only exercised the template's match/P example API. Removing it
first lets the modules and exports it imports go next without leaving a
dangling reference.
Turn off `eslint/no-ternary` and `eslint/capitalized-comments` in the
project config: both encode a style the project rejects, so they belong in
the config's rule map rather than a per-site disable.
Scope the adjacent `oxlint-disable` decision to false positives and
record why a rejected stylistic rule is turned off project-wide.
Type-driven tests: every expectTypeOf pairs an assert, covering the
header matrix (exhaustive vs partial patterns, strict R vs widened
returns, string and numeric keys, _ fallback wiring).
Negative cases use Parameters<typeof factory>[0] assignability because
expect-type's .not.toBeCallableWith collapses to never on these generic
Simplify<>-wrapped signatures.
Same documented expectTypeOf floating-promise false positive as
index.test.ts, so the same file-level disable applies; testing.md
known-issue updated to list both files.
Actionable sentence in CONTRIBUTING.md § Rules the tools don't enforce;
the why — humans skim, agents imitate the dominant style, so verbosity
compounds — in development/README.md § Decision blocks. Both sides in
one commit per the write-each-fact-once rule.
DefinitelyTyped keeps the @types/node latest dist-tag on the LTS line,
so check-outdated compared the current-line types against a lower
version: a permanent "reverted" flag, scan exit 1, zero signal. Ignored
by package name; --types filtering and a version-scoped pin rejected
(rationale in development/tooling.md).
`create:finish` leaves the merge local until `create:release` pushes it, so
`main` is routinely ahead of its upstream between a merge and a release. The
branch front door demanded an exact match and refused until it was pushed,
forcing a manual `git push` that the model deliberately keeps out of it.
Reject only a `main` that is behind its upstream — matching `create:finish`,
which already tolerates being ahead — and record why pushing from `finish` was
rejected instead. The push stays with `create:release`, so the merge remains
reviewable locally, and the known issue about the deadlock is gone.
Resolves: backlog task "Resolve the finish/push tension".
A merged branch must carry a final commit adding a short summary of the
work under [Unreleased] in CHANGELOG.md. create:release derives the bump
heuristic from that body, so notes have to exist before release day;
rationale in development/workflow.md.
Same decisions, rationale, rejected alternatives and known issues, said with
less padding: ~5,530 -> ~4,730 words (-15%). Every fact from the first draft is
kept; only the wording, duplicated lead-ins and restated context are cut.
The GitHub Flow description and the type-first enforcement sentence still
appeared in both CONTRIBUTING.md and development/. development/ now carries only
the context and rationale that is not in CONTRIBUTING.md.
development/ had restated the actionables that CONTRIBUTING.md owns: the
branching step list, the script prefix list, the feedback-tier rule of thumb,
the commit convention and the type-driven test loop. Those now live only in
CONTRIBUTING.md; development/ keeps the decision blocks and links to the rule.
development/README.md, CONTRIBUTING.md and AGENTS.md state the 'write each fact
once' principle explicitly.
AGENTS.md and CONTRIBUTING.md now state that a decision, its rejected
alternatives and its known issues belong in development/<category>.md, that the
actionable rule stays in CONTRIBUTING.md, and that both change in the same
commit. development/README.md names library.md in the category list and spells
out that the sync runs in both directions.
Category files under development/ replace the decision prose that was
scattered through README.md and CONTRIBUTING.md. Each decision is a block with
Decision (YYYY-MM) / Why / Rejected / Known issue; the new library.md records
the public API contract and its limitations. AGENTS.md and backlog.tasks now
point at the new home.
tmu